LONG-LIVED PLASMA CELLS

DESCRIPTION

The invention relates to an isolated polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NO 1 (EEAEKAKEAAEKALNEAFE) or an amino acid sequence with a sequence identity of least 70 %, preferably of at least 80 %, more preferably of at least 90 % to SEQ ID NO 1 , wherein the polypeptide is no longer than 200, preferably no longer than 170 amino acids. The invention relates to a nucleic acid encoding for said polypeptide, a gene therapy vector comprising said nucleic acid and genetically modified cells expressing said polypeptide. Furthermore, the invention relates to the medical use of said polypeptide, said nucleic acid, said gene therapy vector and/or said cell for the treatment of a disease associated with pathogenic long-lived plasma cells.

BACKGROUND OF THE INVENTION

BM is the central tissue for hematopoesis as well as for immunological memory. Hematopoietic stem cells, B-cell precursors, plasma cells and memory T cells reside in distinct specialized stromal niches in the BM (Nagasawa et al., 2006; Wilson and Trumpp, 2006; Tokoyoda et al., 2010). These stromal niches provide cell adhesion molecules like VCAM-1 , laminin, fibronectin and collagens, as well as cytokines and chemokines such as CXCL12, IL-7, IL-15, Kit ligand, SCF, Flt3 ligand to support survival, expansion and differentiation of hematopoietic cells (Clark and Keating, 1995; Anthony and Link, 2014). In the late phase of immune responses, some antigen-experienced plasma blasts migrate into the BM in a CXCR4/CXCL12-dependent manner (Hargreaves et al., 2001 ; Tokoyoda et al., 2004) and reside there as long-lived 'memory' plasma cells (Radbruch et al., 2006). Eosinophils and megakaryocytes play an important role as components of survival niches for plasma cells, secreting APRIL and IL-6 to promote plasma cell survival (O'Connor et al., 2004; Winter et al., 2010; Chu et al., 201 1). Reynolds et al. showed that IgM-secreting plasma cells do not co-localize with eosinophils like IgG-secreting plasma cells, suggesting that IgM- and IgG-secreting plasma cells localize in distinct survival niches in the BM (Reynolds et al., 2015). However, it still remains unclear whether class-switched and un-switched plasma cells share the same survival niches.

Long-lived plasma cells are refractory to immunosuppressants and B-cell depletion therapies contribute to the maintenance of humoral memory and, in autoimmunity, to autoreactive memory. Consequently, long-lived plasma cells can support chronic inflammatory processes in

autoimmune diseases by continuously secreting pathogenic antibodies. As long-lived plasma cells are not sufficiently eliminated by current therapies, there remains a significant need in the art to develop new therapeutic concepts for the treatment of diseases associated with pathogenic long-lived plasma cells such as multiple myeloma or autoimmune diseases.

The gram-negative bacterium Salmonella enterica is responsible for high mortality and morbidity in human worldwide (Andrews-Polymenis et al., 2010). Salmonella enterica serovar Typhi causes enteric fever and kills around 200,000 persons every year. Salmonella enterica serovar

Typhimurium has been widely used as an experimental model for typhoid fever (Santos et al., 2001 ). Following infection via intestinal epithelia, Salmonella invades myeloid cells, which migrate into the spleen and liver (Bueno et al., 2008; Dougan and Baker, 2014; Tam et al., 2014).

Salmonella can stay in myeloid cells for long periods of time. However, it is still unknown how Salmonella can survive long-term in short-lived and mobile myeloid cells to escape from humoral immunity.

It has been described previously that Salmonella enterica serovar Typhimurium encodes for a type I secretion system, which secretes an ~600-kDa protein called SiiE (encoded by s/ ^' / ^' E). SiiE is surface expressed and it influences colonization in cattle and the invasion of bovine enterocytes (E. Morgan et al. Infection and Immunity, vol. 75, no. 3, 1 March 2007, pages 1524-1533). The sequence of SiiE has been described in WO 02/077183 A2, which relates to the use of nucleic acid antisense sequences for inhibiting proliferation of prokaryotes and identifying proteins required for proliferation, with the goal of developing antibiotics.

Infection with Salmonella enterica serovar Typhi can be prevented by vaccination with attenuated strains, e.g. Ty21 a (Anwar et al., 2014). In contrast, vaccination against Salmonella enterica serovar Typhimurium, which causes severe food poisoning in humans, cattle, swine, sheep, horses, rodents and galliformes is not yet available. The use of attenuated genetically engineered bacteria for immunization has been described in the prior art (US 8,771 ,669 B1). However, diseases caused by these invasive nontyphoidal Salmonella (NTS), including Salmonella enterica serovar Typhimurium, have been neglected, although the fatality rate at 20-25% is higher than that by infection with Salmonella enterica serovar Typhi (MacLennan et al., 2014). Accordingly, there remains a significant need in the art to develop vaccines or vaccination strategies that prevent infections with NTS bacteria.

In light of the prior art, there remains a significant need to provide means for improved treatment of diseases associated with pathogenic long-lived plasma cells as well as efficient vaccination strategies against nontyphoidal Salmonella (NTS).

SUMMARY OF THE INVENTION

In light of the prior art, the technical problem underlying the present invention is to provide alternative and/or improved means for the treatment of diseases associated with pathogenic long- lived plasma cell. Furthermore, an efficient vaccine against nontyphoidal Salmonella (NTS) bacteria is highly desirable.

The technical problem underlying the present invention is solved by the features of the independent claims. Preferred embodiments of the present invention are provided by the dependent claims.

The invention therefore relates to an isolated polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NO 1 (EEAEKAKEAAEKALNEAFE) or an amino acid sequence with a sequence identity of least 70 %, preferably of at least 80 %, more preferably of at least 90 % to SEQ ID NO 1 , wherein the polypeptide is no longer than 200, preferably no longer than 170 amino acids.

The present invention is based on the surprising finding that the isolated polypeptide of the present invention can reduce the number of plasma cells in the bone marrow. The peptides of the present invention share a high sequence similarity with a conserved sequence comprised in laminin β1 in many species including humans, mice, pigs, whale, bovine, chicken and even alligator. Laminin β1 is a component of the extracellular matrix and is a member of the laminin family of extracellular matrix glycoproteins, which are a major non-collagenous constituent of basement membranes. Laminins have been implicated in a wide variety of biological processes including cell adhesion, differentiation, migration, signalling, neurite outgrowth and metastasis.

It was surprising that plasma cells, and especially long-lived IgG producing plasma cells in the bone marrow, interact with laminin β1 , which is present in the bone marrow stroma and co- localizes with the bone marrow niche of long-lived plasma cells (LLPC). Upon administration of the peptides of the present invention, the number of plasma cells and especially IgG-producing LLPC in the bone marrow is reduced. Without being bound by theory, this is thought to be due to disruption of the interaction between laminin β1 and LLPC in the bone marrow niches through competition between laminin β1 and the peptides of the present invention for interaction with the plasma cells. Plasma cells can preferentially bind to the peptides of the present invention instead of binding to laminin β1 , leading to the release of plasma cells from their niche and strong reduction of plasma cell numbers in the bone marrow. This reduction may be due to apoptosis and/or emigration of the plasma cells from the bone marrow.

It is a particular advantage of the peptides of the present invention that they can be used to reduce the numbers of plasma cells in the bone marrow, because bone marrow resident plasma cells and specifically LLPC are involved in many pathological processes, such as autoimmunity, allergy and development of plasma cell derived cancers. Due to their localization in protected survival niches in the bone marrow, pathogenic LLPC are refractory to immunosuppressive therapies. Similarly, plasma cell derived cancer cells can occupy these protected niches, where they are not accessible for anti-cancer therapies, such as B cell depletion and chemotherapy.

The fact that the peptides of the present invention share high sequence homology with a sequence of laminin β1 , which is conserved in many species including human and many productive livestock and farm animals, such as rodents, cattle, horses, sheep, swine and galliformes, is a great advantage of the present invention, because LLPC depletion from the bone marrow can be achieved in multiple species.

Furthermore, it is advantageous that upon administration of the peptides of the present invention not only the number of LLPC in the bone marrow is reduced, but also the amount of circulating antibodies. Antibodies that are secreted by LLPC residing in the protected bone marrow niches are a major cause of autoimmune and allergic symptoms that are associated with pathogenic LLPC. Accordingly, a reduction of circulating antibodies upon administration of polypeptides of the invention leads to clinical improvements of patients suffering from such pathologies.

It was surprising that the peptides of the present invention bind specifically to plasma cells in the bone marrow and in particular to LLPC, whereas binding to plasma cells in other organs such as the spleen is less efficient. Accordingly, the peptides of the present invention do not deplete plasma cells of the spleen or other organs to the same extent as the bone marrow resident plasma cells. This is particularly advantageous, because bone marrow plasma cells and in particular LLPC are associated with autoimmune diseases, allergies, cancer and other pathologies, while plasma cells of other organs are less implicated in such conditions.

It is a further advantage of the present invention that in some embodiments the polypeptides of the invention do not have to be administered locally to the site of LLPC in the bone marrow, but can be administered systemically. Therefore, various routes of administration can be employed. Furthermore, the peptides have an unexpectedly high stability at different temperatures, which enables prolonged storage of the peptides under different storage conditions. Also, it is advantageous that the peptide is stable upon administration to a subject, so that an effect can be observed even one day or more after a single administration of a polypeptide of the present invention.

The peptides of the present invention were identified as being comprised by the Salmonella enterica serovar Typhimurium protein SiiE. Infection with Salmonella expressing SHE can lead to a reduction of LLPC in the bone marrow and a reduction of circulating IgG antibodies. This effect can be attributed to the SiiE protein, which is expressed by Salmonella, since infection with SiiE deficient bacteria, which are otherwise identical, do not have this effect. It is known that SiiE is secreted by Salmonella and is subsequently processed. SiiE is a large protein of 5559 amino acids, with 2 distinct regions in the N- and C-terminus and 53 repeated bacterial Ig domains in between. SiiE has a high homology to a conserved region of laminin β1 , which is localized in the N-terminal region of the protein (AA 1 -404 of SiiE of Salmonella enterica serovar Typhimurium).

The most similar amino acid sequence with resepct to sequence identity between SiiE and laminin β1 is located between amino acids (AA) 136-154 of SiiE of Salmonella enterica serovar Typhimurium, which corresponds to SEQ ID NO:1 of the present invention. It is particularly advantageous that a polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NO 1 (EEAEKAKEAAEKALNEAFE) or an amino acid sequence with a sequence identity of least 70 %, preferably of at least 80 %, more preferably of at least 90 % to SEQ ID NO 1 , wherein the polypeptide is no longer than 200, preferably no longer than 170 amino acids, can be used to reduce the number of plasma cells in the bone marrow and reduce the number of circulating IgG antibodies, because such short peptides can be easily produced through chemical or biochemical methods known to the person skilled in the art. In some cases, peptides with a length of more than 200 amino acids, comprising SEQ ID NO 1 or an amino acid sequence with a sequence identity of least 70 %, preferably of at least 80 %, more preferably of at least 90 % to SEQ ID NO 1 , did not lead to the same effect.

In a preferred embodiment, the polypeptide of the present invention comprises or consists of an amino acid sequence according to SEQ ID NO 2 (KEADKA-

KEEAEKAKEAAEKALNEAFEVQNSSKQIEEMLQN) or an amino acid sequence with a sequence identity of at least 70 %, preferably of at least 80 %, more preferably of at least 90 % to SEQ ID NO 2.

The amino acid sequence corresponding to SEQ ID NO: 2, which is comprised by SiiE protein of comprised by Salmonella enterica serovar Typhimurium (AA 129-168) and has a high sequence homology to laminin β1 , specifically reduces the number of IgG secreting plasma cells in the bone marrow and reduces the number of circulating IgG antibodies. This effect is highly specific since IgM antibodies are preferably not affected by the peptides of the present invention. Also, plasma cells of other tissues and organs than the bone marrow are preferably not affected.

According to a further preferred embodiment of the present invention, the polypeptide comprises or consists of an amino acid sequence according to SEQ ID NO 3

(SAQVEKKGNGKRRNKKEEEELKKQLDDAENAKKEADKAKEEAEKAKEAAEKALNEA FE-

VQNSSKQIEEMLQNFL) or an amino acid sequence with a sequence identity of at least 70 %, preferably of at least 80 %, more preferably of at least 90 % to SEQ ID NO 3. The amino acid sequence corresponding to SEQ ID NO: 3, which is comprised by SiiE protein of comprised by Salmonella enterica serovar Typhimurium (AA 97-170) and has a high sequence homology to laminin β1 , specifically interacts with IgG secreting plasma cells from the bone marrow, but to a much lesser extent with plasma cells from other tissues such as the spleen. A further preferred embodiment of the present invention relates to a polypeptide comprising or consisting of an amino acid sequence according to SEQ ID NO 4

(MGNKSIQKFFADQNSVIDLSSLGNAKGAKVSLSGPDMNITTPRGSVIIVNGALYS- SIKGNNLAVKFKDKTITGAKILGSVDLKDIQLERIDSSLVDSAQVEKKGNGKRRN- KKEEEELKKQLDDAENAKKEADKAKEEAEKAKEAAEKALNEAFEVQNSSKQIEEMLQNFL ) or an amino acid sequence with a sequence identity of at least 70 %, preferably of at least 80 %, more preferably of at least 90 % to SEQ ID NO 4.

Preferably, the polypeptide of the present invention comprises at least an amino acid sequence according to SEQ ID NO 1 (EEAEKAKEAAEKALNEAFE).

According to further preferred embodiment, the polypeptide comprises at least an amino acid sequence according to SEQ ID NO 1 (EEAEKAKEAAEKALNEAFE) or SEQ ID NO 2

(KEADKAKEEAEKAKEAAEKALNEAFEVQNSSKQIEEMLQN).

Furthermore, the polypeptide described herein may comprise at least an amino acid sequence according to SEQ ID NO 1 (EEAEKAKEAAEKALNEAFE), SEQ ID NO 2

(KEADKAKEEAEKAKEAAEKALNEAFEVQNSSKQIEEMLQN), or SEQ ID NO 3

(SAQVEKKGNGKRRNKKEEEELKKQLDDAENAKKEADKA- KEEAEKAKEAAEKALNEAFEVQNSSKQIEEMLQNFL).

The present invention further relates to a polypeptide comprising or consisting of a polypeptide described herein for use as a medicament in the treatment of a disease associated with pathogenic long-lived plasma cells.

LLPC secrete high levels of antibodies, wherein LLPC comprise, without limitation, IgM-secreting LLPC, IgG-secreting LLPC, IgA-secreting LLPC and IgE-secreting LLPC. Furthermore, LLPC cannot switch antibody classes and cannot act as antigen-presenting cells. LLPC constitute an independent component of immunological memory. They are generated in the context of memory immune reactions and migrate to the bone marrow, where they persist for years and potentially decades. Their survival is dependent on receiving distinct signals provided by cells forming a plasma cell survival niche. Without being bound by theory, displacement of a plasma cell or long- lived plasma cell from the survival niche may result in apoptosis of the cell.

Pathogenic long-lived plasma cells are long-lived plasma cells that are involved in pathological processes such as autoimmune disease, allergies or cancerous malignancies. As a consequence of their longevity and persistence, pathogenic long-lived plasma cells can support chronic inflammatory processes in autoimmune diseases by continuously secreting pathogenic antibodies, and they can contribute to flares of symptoms. Pathogenic long-lived plasma cell as non-pathogenic plasma cells are protected in their survival niche in the bone marrow and may be refractory to immunosuppression, B cell depletion, chemotherapy and irradiation. Their elimination remains an essential therapeutic challenge.

In some embodiments it is a particular advantage of the peptides of the present invention that they can specifically reduce the number of bone marrow resident plasma cells and in particular bone marrow resident LLPC, which comprise pathogenic LLPC. Depletion of these cells might directly lead to a clinical improvement of subjects suffering from pathogenic LLPC associated diseases. Additionally, as the peptides of the present invention can lead to a displacement of pathogenic LLPC from their protected niches, the cells will become accessible to other treatment strategies, such as B cell depletion, chemotherapy, irradiation.

According to a preferred embodiment of the present invention, the disease associated with pathogenic long-lived plasma cells is multiple myeloma.

Multiple myeloma can be caused by redundant titers of antibodies generated from plasma cell myeloma in the BM. Multiple myeloma is a B cell malignancy of mature plasma cell morphology characterized by the neoplastic transformation of a single clone of plasma cells. These plasma cells proliferate in BM and may invade adjacent bone and sometimes the blood. It has already been reported that myeloma cells that reside in the bone marrow, similar to LLPC, can bind to laminin.

Accordingly, the disruption of the interaction between myeloma cells and laminin by the peptides of the present invention preferably leads to emigration of myeloma cells from their niches, which will make myeloma cells more vulnerable to be eliminated or killed, for example by apoptosis, the body's immune system and/or by further therapies that are applied to the body such as chemotherapy, B cell depletion, irradiation or other therapeutic strategies for cancer or multiple myeloma that are known to the person skilled din the art.

It is a particular advantage of the peptides of the present invention that they are specific to bone marrow resident plasma cells, so that not all plasma cells in the body of a subject that is treated by the polypeptides of the invention are depleted and no severe immuno-suppression is induced.

In a further preferred embodiment of the invention, the disease associated with pathogenic long- lived plasma cells is an auto-antibody-associated autoimmune disease.

In auto-antibody-associated autoimmune disease autoreactive LLPC continuously secrete Abs, resulting in chronicity or relapse of autoimmunity. Current therapeutic strategies primarily target the inflammatory processes and activated immune cells. Nonsteroidal anti-inflammatory drugs, antimalarials, glucocorticoids, conventional immunosuppressive or cytotoxic drugs, as well as cell depletion antibodies such as anti-CD20 (rituximab) targeting B lymphocytes can efficiently reduce the acute or chronic inflammation. They can also abrogate temporary PC survival niches in inflamed tissues and thus eliminate LLPCs in these organs. However, LLPCs in the bone marrow are typically not effectively targeted by such B cell depletion antibodies. With the peptides of the present invention it is now possible to deplete pathogenic LLPC from their remote survival niches in the bone marrow, which may lead to apoptosis or emigration of the cells from the niches, which makes them accessible to further therapeutic measures that are ineffective when the LLPC remain in their niches. Accordingly, the peptides of the present invention potentially enable a more efficient treatment of auto-antibody associated autoimmune disease in comparison to known therapeutic strategies.

Preferably, the disease associated with pathogenic long-lived plasma cells is rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE).

RA and SLE are very relevant and common auto-antibody-associated autoimmune diseases and patients suffering from these diseases might in particular benefit from treatment with peptides of the present invention. In particular, the peptides of the present invention lead to a reduction of the number of autoreactive plasma cells in the bone marrow of subjects suffering from SLE.

In the context of the present invention, it is preferred that the pathogenic long-lived plasma cells are IgG-secreting plasma cells.

Most LLPC associated pathologies are mediated specifically by IgG-producing LLPC and not by LLPC that secrete other antibody classes. It is a particular advantage of the peptides of the present invention that they can specifically target IgG-secreting LLPC and not LLPC in general so that in case of an IgG-mediated LLPC associated pathology it is possible to specifically target the pathogenic cells, while LLPC that secrete for example IgM or other antibody classes are not affected.

According to a further preferred embodiment of the invention the pathogenic long-lived plasma cells preferably reside in the bone marrow. The localization of the pathogenic LLPC in the bone marrow is particularly advantageous because the peptides of the present invention specifically binding to bone marrow resident LLPC and not to LLPC in other tissues. Accordingly, the peptides only affect and/or deplete bone marrow LLPC, but not non-pathogenic LLPC or plasma cells of other tissues.

In another preferred embodiment of the invention, the pathogenic long-lived plasma cells interact with laminin β1 -positive stroma cells.

It is advantageous in some embodiments to treat diseases that are associated with pathogenic LLPC that interact with laminin β1 or laminin β1 -positive stroma cells, because the interaction of the LLPC with laminin β1 can be disrupted through administration of peptides of the present invention. Function and/or survival of the pathogenic LLPC may depend on the interaction with laminin β1 and therefore administration of peptides of the present invention can be detrimental for the pathogenic LLPC. The cells may be depleted, either through immigration or cell death. Also, the cells may be accessible to further treatments, such as administered drugs that directly or indirectly target pathogenic LLPC that have left their protected niches in the bone marrow upon administration of peptides of the present invention.

According to a preferred embodiment of the present invention, the treatment comprises the combined administration of said polypeptide with an anti-B cell therapy, an immunosuppressive drug or an anti-tumor chemotherapy.

According to a preferred embodiment of the present invention, the treatment comprises the combined administration of said polypeptide with an anti-B cell therapy, an immunosuppressive drug and/or an anti-tumor chemotherapy.

It is advantageous in some embodiments to combine administration of peptides of the present invention with the administration of further therapeutic measures. Such measures may comprise anti-B cell therapies, B cell depletion, anti-tumor or anti-cancer chemotherapy,

immunosuppressive drugs, immunomodulatory drugs, irradiation and any further treatment options that are known to the person skilled in the art. It is known that pathogenic LLPC are protected by their specific niche in the bone marrow and are not readily accessible to the above- mentioned therapies. Administration of peptides of the present invention displaces pathogenic LLPC from their bone marrow niche and makes them accessible to the drugs and measures that can be administered in combination with polypeptides of the invention. The increased effect of these therapeutic measures on displaced pathogenic LLPC together with the lack of survival signals provided by the bone marrow niche leads to cell death and reduction or depletion of LLPC ultimately leads to an improvement of the clinical symptoms of the patient.

Furthermore, the present invention relates to a nucleic acid molecule, preferably for use as a medicament in the treatment of a disease associated with pathogenic long-lived plasma cells as described herein, wherein the nucleic acid molecule encodes a polypeptide of the present invention.

Additionally, the invention encompasses a gene therapy vector, preferably for use as a medicament in the treatment of a disease associated with pathogenic long-lived plasma cells as described herein, comprising a nucleic acid molecule of the present invention.

It can be advantageous in some embodiments to provide peptides of the present invention through administration of a nucleic acid molecule encoding a polypeptide of the present invention or through a gene therapy vector comprising a nucleic acid molecule encoding a polypeptide of the present invention. In these embodiments sustained expression of polypeptides or the present invention is possible with only a single administration. Furthermore, nucleic acids molecules and in particular DNA is very stable and can be stored for prolonged periods at room temperature without the risk of significant degradation, which is a great advantage with respect to availability.

The present invention further relates to a cell, preferably for use as a medicament in the treatment of a disease associated with pathogenic long-lived plasma cells as described herein, wherein the cell is a Salmonella bacterium comprising a nucleic acid region encoding a polypeptide of the present invention, or the cell is genetically modified and comprises an exogenous nucleic acid region encoding a polypeptide of the present invention, or an exogenous nucleic acid region of the present invention, and wherein the exogenous nucleic acid region is operably linked to a promoter.

In some embodiments it is particularly advantageous to use cells or even bacteria, such as

Salmonella, as a vehicle to deliver a nucleic acid and ultimately peptides of the present invention to a subject suffering from a disease associated with pathogenic LLPC. Administration of Salmonella bacteria encoding SHE protein leads to depletion of LLPC in the bone marrow and a reduction of IgG. This shows that instead of administering a polypeptide of the present invention such peptides can be also provided through administration of cells or bacteria that provide expression of such peptides.

The present invention also relates to a pharmaceutical composition for use as a medicament in the treatment of a disease associated with pathogenic long-lived plasma cells as described herein, comprising a polypeptide of the present invention, a nucleic acid molecule a of the present invention, a gene therapy vector of the present invention and/or a cell of the present invention, and a pharmaceutically accepted carrier.

Moreover, the present invention relates to a mutant nontyphoidal Salmonella (NTS) bacterium for use as a vaccine in the prevention of a NTS infection in a subject, wherein the mutant NTS bacterium does not express a polypeptide comprising or consisting of a SiiE polypeptide as described herein.

This embodiment of the invention is based on the surprising finding that infection with a

Salmonella that does not express SiiE or any other polypeptide comprising a polypeptide of the present invention, leads to a strong humoral/antibody-based immune response against

Salmonella. This does not occur upon infection with wild-type Salmonella expressing SiiE. On the contrary, SiiE expressing Salmonella bacteria typically lead to a reduction of plasma cells in the bone marrow and a reduced IgG antibody titer. Accordingly, Salmonella induces an immune reaction and impairs immune memory in an SiiE-dependent manner.

SiiE deficient NTS can be used as a vaccine generating typically higher IgG antibody titers against NTS in a host, which is subsequently protected against infection with wild-type NTS expressing SiiE.

To date, vaccination against NTS, and in particular against Salmonella enterica serovar

Typhimurium, which causes severe food poisoning in humans, cattle, swine, sheep, horses, rodents and galliformes, is not available. Furthermore, invasive strains of nontyphoidal

Salmonellae (iNTS) have emerged as a prominent cause of bloodstream infection in African adults and children. Diseases caused by invasive nontyphoidal Salmonella (iNTS), including Salmonella enterica serovar Typhimurium, have been neglected, although the fatality rate at 20- 25% is higher than that by infection with Salmonella enterica serovar Typhi.

In contrast, infection with Salmonella enterica serovar Typhi, which is restricted to humans and causes severe and often fatal typhoid fever, can be prevented by vaccination with attenuated strains, e.g. Ty21 a. In the context of the present invention, it was found that Salmonella enterica serovar Typhi most likely does not express a functional SiiE protein comprising a polypeptide of the present invention, which, without be ing bound by theory, is alikely explanation of why a vaccination against Salmonella Typhi is available.

Preferably, the mutant NTS bacterium for use as a vaccine described herein exhibits a deletion of the SiiE encoding gene.

In a preferred embodiment of NTS bacterium for use as a vaccine, the subject is a human, galliformes, cattle, sheep, swine, horse or rodent.

Wild-type Salmonella mediates the inhibition of an humoral immune response through SiiE, which comprises a polypeptide of the present invention inhibiting the interaction of bone marrow plasma cells with laminin β1. This leads to a depletion of bone marrow plasma cells and a reduction of antibodies. Since laminin β1 is conserved among many species, including the species comprised by human, galliformes, cattle, sheep, swine, horse and rodent, it is in some embodiments possible to use NTS that do not express polypeptides that comprise polypeptides of the present invention as a vaccine in these species.

Preferably, the mutant NTS bacterium for use as a vaccine is a Salmonella enterica serovar Typhimurium.

The polypeptides of the present invention, the polypeptides for use as a medicament in the treatment of a disease associated with pathogenic long-lived plasma cells, and the mutant nontyphoidal Salmonella (NTS) bacterium for use as a vaccine in the prevention of a NTS infection in a subject claimed herein, are based on the same inventive concept that polypeptides of the present invention induce a reduction or depletion of plasma cells and in particular LLPC in the bone marrow, which is accompanied by a reduction of the antibody titer. This concept can be employed in situations where a reduction of LLPC in the bone marrow and a reduction of the antibodies produced by these cells is desirable, such as in subjects suffering from diseases that are mediated by pathogenic LLPC. On the other hand, the same concept has been applied for the development of the presently claimed mutant NTS for use as a vaccine against NTS infection. In this case, a strong LLPC mediated humoral immune response is desirable to establish immune memory for NTS to prevent future infections. However, upon infection with wild-type NTS the humoral immune response and immune memory can be suppressed due to polypeptides of the present invention, such as fragments of SiiE. By using mutant NTS that do not express SiiE or a polypeptide that comprises a polypeptide of the present invention as a vaccine, for example by infecting a subject with such a mutant NTS, the immune system of said subject can generate a robust humoral immune response that results in the generation of NTS-specific LLPC that can reside for prolonged periods in the bone marrow niches.

Therefore, it can be concluded that the (1) SiiE polypeptides of the present invention and their relevance in treating diseases associated with pathogenic long-lived plasma cells, and the (2) mutant nontyphoidal Salmonella (NTS) bacterium that does not express a SiiE polypeptide as described herein and their relevance as a vaccine in the prevention of a NTS infection in a subject, as claimed herein, are based on a single technical concept, which enables solutions for providing alternative and/or improved means for the treatment of diseases associated with pathogenic long-lived plasma cell as well as the provision of an efficient vaccine against nontyphoidal Salmonella (NTS) bacteria. A special technical feature linking these aspects of the invention can be phrased as the function of SiiE protein as described herein on long-lived plasma cells, namely that polypeptides of the present invention induce a reduction or depletion of plasma cells and in particular LLPC in the bone marrow, which is accompanied by a reduction of the antibody titer. The functional connection between SiiE protein and long-lived plasma cells is directly relevant for both the therapeutic use of the SiiE protein and the absence of the SiiE protein in mutant nontyphoidal Salmonella (NTS) bacterium for use as a vaccine in the prevention of a NTS infection in a subject, as both embodiments are based on the effect of SiiE on plasma cells. No suggestion is evident in the prior art of the relationship between SiiE and plasma cells, and therefore the two aspects of the invention described above are linked by a unique and unitary functional feature.

Accordingly, the claimed polypeptide of the present invention, the claimed use of the polypeptide of the present invention as well as the claimed use of the mutant NTS that do not express a polypeptide that comprises a polypeptide of the present invention are all based on the common concept that polypeptides of the present invention induce a depletion of LLPC from the bone marrow.

DETAILED DESCRIPTION OF THE INVENTION

All cited documents of the patent and non-patent literature are hereby incorporated by reference in their entirety.

Amino acid sequences of preferred polypeptides of the present invention are listed under Table 1. Table 1: Amino acid sequences of preferred neuregulin proteins SEQ ID NO 1 : EEAEKAKEAAEKALNEAFE

Amino acid (AA) sequence

of AA 136-154 of SiiE

(large repetitive protein SiiE

[Salmonella enterica subsp.

enterica serovar

Typhimurium]; GenBank:

ASF67203.1

SEQ ID NO 2: KEADKAKEEAEKAKEAAEKALNEAFEVQNSSKQIEEMLQN

Amino acid (AA) sequence

of AA 129-168 of SiiE

(large repetitive protein SiiE

[Salmonella enterica subsp.

enterica serovar

Typhimurium]; GenBank:

ASF67203.1

SEQ ID NO 3: SAQVEKKGNGKRRNKKEEEELKKQLDDAENAKKEADKAKEEAE

KAKEAAEKALNEAFEVQNSSKQIEEMLQNFL

Amino acid (AA) sequence

of AA 97-170 of SiiE (large

repetitive protein SiiE

[Salmonella enterica subsp.

enterica serovar

Typhimurium]; GenBank:

ASF67203.1

SEQ ID NO 4: MGNKSIQKFFADQNSVIDLSSLGNAKGAKVSLSGPDMNITTPRGS

VIIVNGALYSSIKGNNLAVKFKDKTITGAKILGSVDLKDIQLERIDSS

Amino acid (AA) sequence LVDSAQVEKKGNGKRRNKKEEEELKKQLDDAENAKKEADKAKE of AA 1-170 of SiiE (large EAEKAKEAAEKALNEAFEVQNSSKQIEEMLQNFL

repetitive protein SiiE

[Salmonella enterica subsp.

enterica serovar

Typhimurium]; GenBank:

ASF67203.1

SEQ ID NO 5: Full length MGNKSIQKFFADQNSVIDLSSLGNAKGAKVSLSGPDMNITTPRGS SiiE (AA 1-5559) (large VIIVNGALYSSIKGNNLAVKFKDKTITGAKILGSVDLKDIQLERIDSS repetitive protein SiiE LVDSAQVEKKGNGKRRNKKEEEELKKQLDDAENAKKEADKAKE [Salmonella enterica subsp. EAEKAKEAAEKALNEAFEVQNSSKQIEEMLQNFLADNVAKDNLA enterica serovar QQSDASQQNTQAKATQASKQNDAEKVLPQPINKNTSTGKSNSS Typhimurium]; GenBank: KNEENKLDAESVKEPLKVTLALAAESNSGSKDDSITNFTKPQFVG ASF67203.1 STAPNATVIIKINGIAVGQAVADSLGNFTFTAPETLTDGTYNLEAEA

KTADGSGSAKLVITIDSVTDKPTFELSPESSVSGHKGLTPTLTPSI

VGTAEENAKVDIYVDNKLVASVDVDKDGNWSYEFKDNELSEGEN

SIKVVAVDKAGNKNETTDSIITDTIAPEKPTIELDDSSDSGIKNDNIT

NSTLPTFIGVAEPGSTVSIYLGLKHLGEVIVAKDGTWSYTLTTPLK

DGEYNITATATDIAGHTSATANLPFTIDTRISYFSAEIETTNDSGIV

GDNVTNNTRPTFTGKTEPNAIISVINSETGEEVIFKANDKGEWTFN

FTSDSVEGINNLTFTVEDVAGNKKDFSFSYVIDTIAPVPPTVSLED

YWLPNGIILSGNDLPALVGTAEPKSTILLMRDGKLYDSIEVDSNG

TWN YQFS N KF LQG AYD I E 11 SQ DAAG N KSSTVKYS FT I QTE VVP P K

AELDASDDSGAKGDWITNKHNALTLLGTADRFATVNILIDGKTIGV

TTADADGNWNFDISRNLSDNVYKITVESIDPLGRTSSVDYQLTIDS

FTPIPTVMLHDSADSGVKGDMITKINTPLFTGMAEANAKVSIYVDG VLSGEAIAGDDGVWNFQFTTALSDGSHDVTVKVEDIAGNTASSS

AYNFQIVTQTQKPTIELVNDTGVDNTDHIINEKNPALTGTAAPYST

VKLYIDGALIAEVRTNKDGRWEYTLKADQGLVDGDHRITASVEDI

AGNIAHSDPFLISVDTAISIPIVSLSPDSDSGISDDNLTNIVKPTLHL

KDIDPDIISVQVWDAMSDTQIGVATQQPDGSWAYTFTSDLTEGLH

QVYVKVEDIAGNKANSAIFDFTIDTTVSTPVISLLSKDDTGVTGDN

LTNINKPGFAISGVDADAHRVWQVMHNGVSEEIELSHLNGSWLF

IPGNTWADGSYTLTVKVEDKAGNTNYSAPLTWIDTQIAIDGVELV

NDSGVKGDNMTNDDRPHFRVTVPTDVNEVRLSIDGGNSWVQAT

PGVAGSWEYIWPTDLADGQYTLTVEATDKAGNTVTKTIDFAVDT

TLSVPVIVLDSADDTGIQGDNMTNSTQPTFALQHIDDDAVRVTVS

VEHGGVTTTFDATKGTGGWTFTPPTSWADGDYTLSVSVEDKAG

NTSHSASLTVTVDTQIAINNIELVNDSGIPDDNLTNNVRPHFQVTV

PTDVNWRLSIDGGKTWFNATQSATPGVWDYIWPDDVADGGYT

LTVEATDEAGNKATQTLDFTIDTTLSVPTLSLDSADDSGIAGDNIT

NVKTPGFTLNNIDTDVSRVIVEVMHNGIKQEVPLVQTGGQWRFA

PTSDWADGDYILTVKVEDRAGNVKQSAPLTVTVDTHIAIDRIELVN

DSGIPGDNLTNEARPH FQVTVPADVN G VR LS I DGG KTWFDATQS

ATSG VWDYTWLT N VANG P HT L M VEAS D KAG N KTTQKLDFT I DT I

LSEPTITLDSADDSAAGDNITNVKMPGFTLGNIDADVTKVWTVAH

DGKNQQIELIKNGGVWRFTPGAAWTDGDYTLTVKVEDKAGNTN

YSAPLTVTIDTQTSIDRIELLNDTGIVGDNLTNEARPQFHITVPTDV

NSVQLSLDGGINVWNATLTSDGVWEYIWPTDLVENTYTLTVKAT

DVAGNTATETLNFIIDTTLSTPTITLDSADDSGTANDNKTNVKTPG

FIIGGIDSDVTQVWQVMRDGHSEEVELTQTNGQWRFVPGSAWT

DGDYTLTVTVKDEAGNIRHSAPLTVTIDTQITIDHIELVNDSGIPDD

NLTNNVRPHFQVTVPTDVNWRLSIDGGKTWFNATQSATPGVW

DYTWLADVGEGKHTLTVEATDKAGNKTTQQLDFIIDTLLSEPTIVL

DSTDDSGTKGDHLTNVNKPTFLLGNIDADARYVTVEVQHGGTKE

VLTAT KDATG N WSVTPTGTWADG DYT LTVRVE DE AG N E KHS AS

LTVTVDTQITIDVIELVNDNGIPGDNMTNDAHPQFRVTVPGDVNE

VSLSIDGGVTWVKATQSATPGVWNYTWPGTVPDGDYTLNVKAT

DNAGNTVTETLHFTIDTTLSTPVIVLDSADDSGVHGDNMTNHTQP

T FA LQ H I D D D AVRVTVSV E H G GVTTT F DAT KD AG G WT FT PTG AW

ADGDYTLSVSVEDKAGNTSHSASLTVTVDTQIAINNIELVNDSGIP

DDNLTNNVRPHFQVTVPTDVNWRLSIDGGKTWFNATQSATPGV

WDYTWLADVG EG KHT LTVEAT D KAG N KTTQQ LD F 11 DTL LS E PT I

VLDNTDDSGTKGDNLTNVNKPTFLLGNIDADARYVTVEVQHGGT

KEVLTATKGATGIWSVTPTGTWADGDYTLTVRVEDDAGNVKYSA

PLTVTVDTQITIDVIELVNDNGIPGDNLTNDVRPHFRVTVPGDVNE

VRLSIDGGNTWVRATQGTAGIWDYTWPKDVTDGLHTLTVEATDK

AGNKTTQTLDFTIDTRLSTPTIAMDSRDDTGAIGDHITSVKRPGFTI

GNIDADAHSVILRITQGGNSQEVTLTQVGGQWRFTPDADWADG

SYTLTVEVTDNAGNVRQSTPLWTVDTQTSITDITLVNDHGVPDD

NLTNSTRPQFEITVPADVNSVQLSIDGGANVWSATQGIEGVWGY

TWPTDMGDGKHTLTVMVTDRAGNTATQTLEFFIDTRLSTPTIALD

STDDTGTPGDDMTNRTRPTFILQNIDSDVINVTVSVTHNGTTTSF

T ATQG AG G WS FTP P AP WG DG DYT LTVTV E D RAG NTRPSTPLTV

TVDTQIAIDRIELVNDSGVPGDNVTKHVRPQFQISVPDDVEKVLLS

I DG GTTWVTA I KS STAG I WD YT WPT DMPEGQHT LTVEVT DG AG N

KMTETLNFTIDITLLTPTIELAPDQDTGQNKNDNLTSVTQPVFVLG

SIDKDVRHVELSIEHNGTFKTWLTESADGWRYRPDSALADGSYT

FTVTVTDVAG N QQTSAP L KVT I DGT LTT PVI E LAAG E DSGTVG D R

LTNHDRPVFDIHQVDSDVTRVMVKVTYNGKTHEEAAVFTNGQW

RFTPSASWADGSYQLAVWEDLAGNVKESAPFEVRIDTTTTINNI

VLLNDTGVQNDQLTNVAKPSFRIDVPGDWQVRVTLDGGANWN

VIRKNADGQWIFDSPNTLVDGTYTLRVEATDEAGNIANKDLVFNI DTNIQVPTIALDAGQDTGANTADNITNISRPTFTIGNVDPDVIKVW

TIDGHDYNATKVGAGWQFTPGNAIPDGSYNITVTVEDKAGNTAT

SKPLPWIDTTAEIESVTLVTDSGDSDVDNITKVDKPQFSIVTADDI

THVRVKIDNAANWIELTKGGDGRWIFNVGSALPDGQHTLLVDVT

DIAGNVAQETLQFTIDTTLREPTIVLDPTHDTGDDTNDNLTRINKP

VFIIGNVDNDVSHIVVHIDGRDYTIENTGGNLTFTPDQPLSDGQHT

ISVTVTDIAGNTKTSAELRIEIDTQVQIDSVTLTTDSGVNDHDNVTN

ATRPSFEIATPDDVTSVLVSFDGVNWTPISKNAAGQWEFTAGSA

LPDGHYTLHVQATDRAGNTANSTLGFTVDTQIDGLSWMLDDAG

KDSTDGITNITSPRFEISAREPLQSVTVILNGKSSTLTQGAGNKWL

FTPDTPLVDGTYKIEIVAEDIAGNKISKEVSFTIDTIVSDPSIDLLDA

DDTG ESAVDN ITSVTT P R FVI G N VPAD I DTVVI R I NG VSYPVTAN G

NNLWEFQVPVALNDGVYEAVWFRDIAGNTSETKLPFTIDTTTSV

SVRMEPASDTGNSNSDNLTNKQNPKFEGTAEPNAKLVITIVDDKS

GREVLKQTITVGADGNWSVTPNILPDGMYTINWATDVAGNTAQ

TQERFTIDTVTIDPTIRLSDPSIDDQHEATSLRPEFKGFAEAFSTIMI

QWDGKWGSANANANGEWSWTPPSVLAPGSYWSIVAKDKAG

NESSQVDFPWIPVIDVTPPTIKLSEESDSGALGDFTTNNKTPTLIG

STLPNTIVSIYVDGVKVGEATADTAGRYTFQLSEMKDGHYWQV

GIVNPRDNSELRSTAVDVTIDTEVAELVWNISGMHEGGYINTVTP

EIGGTSEPNSKITIFVNGVEKAIAYTTGAGHWGWLPALGNDGNY

ELTFKVEDVAGNIREFGPQNVILDTVISPLTWLREADDSGKVGD

WITNKSHVTIDGTAEAGSTLTIRNPQGWIATLWGNDGRWSAEL

DLREGSNAFVWSEDKAGNSQQKEILIEHDTQIEISDISLSRDTNS

GDKYDLITNNKSPVLVAMTDPGATVQVYINGVLQGTVEASSSGNI

SYTMPANSADGEYQVQFVATDTAGNRVESAITTVTIDSQIAVFDID

EDSLPALSNNRALSVSGVGEAGSQVSIFVDGKLVNWMVEADGT

WRAPILLQDDGTFNIHFSITDVAGNTEVSKDYSVDVDSSTDFPTL

NLEDASNSGSLDDLITNHNKPVLVGTAEAGATIHIYVDEKIVANVL

VLEDGTWSYQFDNALKDGEYSIRWAEDPAGNTAESPRLLVTIDT

STFIDNPAMVAGSDNGIFSNDSITSQTRPTFSIFGEMNQSVQIFID

GVLVDTITVTDRNQVYRPESPLGDGSHSIYYVITDKAGNTATSKTL

NFTIDTFNTTPVAIDSIGGQTLAEMTGSDGKIYITDTTRNLLFSGSA

EPNSKIEIIINGLNVGEWWNEKGHWQMPVNPLYFTEGQLDITVK

STDRAGNVNQEKYSIWVDTHIKVFTSELDDNKSSSKTEVWVSNSD

LITMRGTGEIGATVSLIVAGVTLATAWAATGRWELSTDKLPEGTY

DISLVIEDSAGNRWEDVREIFIDRTPPNAPWTYSDIVNDLIIMQGT

AEAKSQLIITDSEGNTYTLTVPDNGKWSMAIPYPSEGKFTITSVDA

IGNRSDDVPLDIMKEVPVISLSPDSDSGTVGDNITRDKQPTFIIGNL

ESDWWQVDINGTVYNAEKNADGVWFFTPGTPLADGSYTISVIA

SDAAGNQKNSLPITVTIDSTLTVPEIALAAGEDNGASDSDNVTNH

TQPKFTLQHIDADVTGVTVNVTHNGVTDIYQATQGADGWTFTPP

AAWNDGNYTLSVTWDRAGNSQQSASLAVTVDSTVTVTADSQH

DDASDDATATAVTPPESETVNAESATHLRTEPSAAEESWKVTA

YSITLLNADSGDEIDRSISQTPSFEISVPENIVNVSIMFEGEEFTLPI

TNQKAIFEVPLSLEDGEYTMDVKFIDKDNDFLIKEKTFSVDHSSAD

IVNAMNVRGKTEDDINDSPSTSSVGHNNNGAIDVFAVNEVTLPVD

NQEEHA

SEQ ID NO 6: mouse VTADMVKEALEEAEKAQVAAEKAIKQADEDIQGTQNLLTSIESE Laminin β1 ; AA 1638-1681 ;

NCBI Reference Sequence:

NP_032508.2

SEQ ID NO 7: human VTADMVKEALEEAEKAQVAAEKAIKQADEDIQGTQNLLTSIESE Laminin β1 ; AA 1590-1633;

GenBank: EAL24388.1 SEQ ID NO 8: N-terminal MGNKSIQKFFADQNSVIDLSSLGNAKGAKVSLSGPDMNITTPRGS domain of SiiE (AA 1-404) VIIVNGALYSSIKGNNLAVKFKDKTITGAKILGSVDLKDIQLERIDSS (large repetitive protein SiiE LVDSAQVEKKGNGKRRNKKEEEELKKQLDDAENAKKEADKAKE [Salmonella enterica subsp. EAEKAKEAAEKALNEAFEVQNSSKQIEEMLQNFLADNVAKDNLA enterica serovar QQSDASQQNTQAKATQASKQNDAEKVLPQPINKNTSTGKSNSS Typhimurium]; GenBank: KNEENKLDAESVKEPLKVTLALAAESNSGSKDDSITNFTKPQFVG ASF67203.1 STAPNATVIIKINGIAVGQAVADSLGNFTFTAPETLTDGTYNLEAEA

KTADGSGSAKLVITIDSVTDKPTFELSPESSVSGHKGLTPTLTPSI

VGTAEENAKVDIYVDNKLVASVDVDKDGNWSYEFKDNELSEGE

In one embodiment the invention therefore encompasses a polypeptide as described herein comprising or consisting of an amino acid sequence selected from the group consisting of:

a) an amino acid sequence comprising or consisting of an amino acid sequence according to SEQ ID NO 1 -4; wherein the polypeptide is preferably no longer than 200, preferably no longer than 170 amino acids;

b) an amino acid sequence comprising or consisting of an amino acid sequence according to SEQ ID NO 1 -4, wherein the length of the amino acid molecule is between 10 and 300 amino acids, preferably between 15 and 200 amino acids, most preferably between 19 and 170 amino acids, wherein the surrounding sequences are preferably provided as SiiE sequences flanking the amino acid sequences according to SEQ ID NO 1 -4.

c) an amino acid sequence having sufficient sequence identity to be functionally

analogous/equivalent to an amino acid sequence according to a), comprising preferably a sequence identity to an amino acid sequence according to a) of at least 70%, 80%, preferably 90%, more preferably 95%; and

d) an amino acid sequence of a), b) or e) which is modified by deletions, additions, substitutions, translocations, inversions and/or insertions and functionally analogous/equivalent to an amino acid sequence according to a), b) or c).

Functionally analogous sequences refer preferably to the ability to encode a functional peptide comprising a homology to a conserved sequence of laminin β1 . Preferably, the conserved sequence of laminin β1 corresponds to an amino acid sequence according to SEQ ID NO 6 or 7.

In this context, functionality may refer to the ability of a peptide to interfere with or inhibit the interaction between long-live plasma cells and laminin β1 in the bone marrow.

Embodiments of the invention may comprise a polypeptide as described herein comprising or consisting of an amino acid sequence SEQ ID NO 1-4, or variants of these sequences, wherein the sequence variant may comprise a sequence identity to SEQ ID NO 1 -4 of 50, 55, 60, 65, 70, 75, 80, 81 , 82, 83, 84, 85, 86, 87, 88, 89, 90, 91 , 92, 93, 94, 95, 96, 97, 98 or 99%. Sequence identity may be determined using methods known to one skilled in the art, such as BLAST or other sequence alignment tools.

In further preferred embodiments, the invention relates to a polypeptide comprising or consisting of an amino acid sequence derived from the N-terminal domain of Salmonella enterica serovar Typhimurium SiiE protein. Preferably, the amino acid sequence derived from the N-terminal domain of Salmonella enterica serovar Typhimurium SiiE protein comprises or consists of an amino acid sequence homologous to a conserved amino acid sequence of laminin β1 . Preferably, the conserved amino acid sequence of laminin β1 has a length of at least 19 amino acids, more preferably 25 amino acids, most preferably 40 amino acids. Sequence homology refers to a sequence identity of more than 65 %, preferably more than 70 %. The N-terminal domain of of Salmonella enterica serovar Typhimurium SiiE protein comprises the amino acids 1-404 of SiiE protein.

SiiE is a large protein of 5,559 amino acids or Salmonella enterica serovar Typhimurium, with 2 distinct regions in the N- and C-terminus and 53 repeated bacterial Ig domains in between (Figure 6). SiiE is secreted and is involved in the adhesion to gut intestinal epithelial cells (Gerlach et al., 2007).

Protein modifications to the polypeptides of the present invention, which may occur through substitutions in amino acid sequence, and nucleic acid sequences encoding such molecules, are also included within the scope of the invention. Substitutions as defined herein are modifications made to the amino acid sequence of the protein, whereby one or more amino acids are replaced with the same number of (different) amino acids, producing a protein which contains a different amino acid sequence than the primary protein. In some embodiments this amendment will not significantly alter the function of the protein. Like additions, substitutions may be natural or artificial. It is well known in the art that amino acid substitutions may be made without significantly altering the protein's function. This is particularly true when the modification relates to a

"conservative" amino acid substitution, which is the substitution of one amino acid for another of similar properties. Such "conserved" amino acids can be natural or synthetic amino acids which because of size, charge, polarity and conformation can be substituted without significantly affecting the structure and function of the protein. Frequently, many amino acids may be substituted by conservative amino acids without deleteriously affecting the protein's function.

In general, the non-polar amino acids Gly, Ala, Val, lie and Leu; the non-polar aromatic amino acids Phe, Trp and Tyr; the neutral polar amino acids Ser, Thr, Cys, Gin, Asn and Met; the positively charged amino acids Lys, Arg and His; the negatively charged amino acids Asp and Glu, represent groups of conservative amino acids. This list is not exhaustive. For example, it is well known that Ala, Gly, Ser and sometimes Cys can substitute for each other even though they belong to different groups.

The present invention encompasses gene therapy comprising the administration of a therapeutic gene encoding the polypeptide described herein.

The term gene therapy preferably refers to the transfer of DNA into a subject in order to treat a disease. The person skilled in the art knows strategies to perform gene therapy using gene therapy vectors. Such gene therapy vectors are optimized to deliver foreign DNA into the host cells of the subject. In a preferred embodiment the gene therapy vectors may be a viral vector. Viruses have naturally developed strategies to incorporate DNA in to the genome of host cells and may therefore be advantageously used. Preferred viral gene therapy vectors may include but are not limited to retroviral vectors such as moloney murine leukemia virus (MMLV), adenoviral vectors, lentiviral, adenovirus-associated viral (AAV) vectors, pox virus vectors, herpes simplex virus vectors or human immunodeficiency virus vectors (HIV-1). However also non-viral vectors may be preferably used for the gene therapy such as plasmid DNA expression vectors driven by eukaryotic promoters or liposomes encapsulating the transfer DNA. Furthermore preferred gene therapy vectors may also refer to methods to transfer of the DNA such as electroporation or direct injection of nucleic acids into the subject. Moreover it may be preferred that the gene therapy vectors for example a viral gene therapy vector is adapted to target bone marrow cells and in particular stroma cells, hematopoietic cells or immune cells of the bone marrow or long-lived plasma cells. To this end the viral capsid may be conjugated with ligands binding to bone marrow cells and in particular stroma cells, hematopoietic cells or immune cells of the bone marrow or long-lived plasma cells such as monoclonal antibodies. It may also be preferred that the viral gene therapy vectors are genetically modified using inducible promoters or promoters that are specific for bone marrow cells and in particular stroma cells, hematopoietic cells or immune cells of the bone marrow or long-lived plasma cells to enhance the expression of the nucleic acid specifically within the bone marrow in the surrounding of pathogenic long-lived plasma cells. Preferred gene therapy vectors may therefore comprise vectors for an inducible or conditional expression of the polypeptides. The person skilled in the art knows how to choose preferred gene therapy vectors according the need of application as well as the methods on how to implement the nucleic acid into the gene therapy vector. (P. Seth et al., 2005, N. Koostra et, al. 2009., W. Walther et al. 2000, Waehler et al. 2007).

The nucleic acid according to the invention and preferred embodiments thereof, in particular a nucleic acid encoding a polypeptide of the present invention, is particularly efficient for gene therapy due to a high therapeutic potential at a small size. This ensures a stable integration at high expression levels over extended periods of times.

In a further preferred embodiment the invention relates to a cell for use as a medicament in the treatment of a disease associated with pathogenic long-lived plasma cells as described herein, wherein the cell is genetically modified and comprises an exogenous nucleic acid region encoding for a polypeptide according to the invention or preferred embodiments thereof and wherein the exogenous nucleic acid region is operably linked to a promoter.

The person skilled in the art knows how to genetically modify cells in order to express the polypeptides according to the inventions. Advantageously by expressing the therapeutically effective polypeptides the cells may act as bio pump or drug factory that continuously expresses and provides the polypeptides to the subject. Thereby the amount of the polypeptides can be held at a therapeutic level over long periods. The person skilled in the art knows which cells may be preferably used to this end. In a preferred embodiment the cells are stem cells, characterized by a stable expression of the polypeptides. Stem cells may include but are not limited to, embryonic stem cells such as early embryonic stem cells and blastocyst embryonic stem cells; fetal stem cells; umbilical cord stem cells; and adult stem cells such as mesenchymal stem cells, hematopoietic stem cells, endothelial stem cells, peripheral blood stem cells, and multipotent somatic stem cells. In another preferred embodiment the cell may be a bacterial cell or a bacterium. Bacteria constitute a large domain of prokaryotic single cell microorganisms, which can be genetically modified by standard microbiology and molecular biology techniques. Besides naturally occurring bacteria, there a genetically modified bacteria and synthetic bacteria. A person skilled in the art is able to select preferably bacterial cells that may be used in the context of the present invention.

Preferably, the bacterial cell is a Salmonella bacterium. Salmonella bacteria are gram-negative bacteria of the Enterobacteriaceae family. The genus of Salmonella bacteria comprises two species, Salmonella bongori and Salmonella enterica, the latter of which is divided into six subspecies (S. e. enterica, S. e. salamae, S. e. arizonae, S. e. diarizonae, S. e. houtenae, and S. e. indica), which contain more than 2500 serotypes (also serovars) defined on the basis of the somatic O (lipopolysaccharide) and flagellar H antigens. The full name of a serotype is given as, for example, Salmonella enterica subsp. enterica serotype Typhimurium, but can be abbreviated to Salmonella Typhimurium. Further differentiation of strains to assist clinical and epidemiological investigation may be achieved by antibiotic sensitivity testing and by other molecular biology techniques such as pulsed-field gel electrophoresis, multilocus sequence typing, and, increasingly, whole genome sequencing. Historically, Salmonellae have been clinically categorized as invasive (typhoidal) or noninvasive (nontyphoidal Salmonellae) based on host preference and disease manifestations in humans. A person skilled in the art can select suitable Salmonella bacterium that may be genetically modified or not that comprises a nucleic acid region encoding a polypeptide of the present invention.

The cells may migrate to the site of the pathogenic long-lived plasma cells in order to locally express the polypeptides in vicinity of the pathogenic cells. Advantageously the cells may however also be transplanted at a different location as the polypeptides can also be transported by the vascular system throughout the body of the subject. Local administration of the cells e.g. by a subcutaneous injection may therefore contribute in a systemic manner largely irrespective of the location of the cells within the body of the subject.

In a further preferred embodiment the cells for use as a medicament as described herein is characterized by introducing a therapeutically effective number of said cells to a subject within a biocompatible matrix. Preferred materials for the biocompatible matrix are agarose, carrageenan, alginate, chitosan, gellan gum, hyaluronic acid, collagen, cellulose and its derivatives, gelatin, elastin, epoxy resin, photo cross-linkable resins, polyacrylamide, polyester, polystyrene and polyurethane or polyethylene glycol (PEG). It is further preferred that the biocompatible matrix is a semi-permeable hydrogel matrix and the cells are entrapped by said matrix. Advantageously the biocompatible matrix allows for an efficient diffusion of nutrients, oxygens and other biomolecules to ensure a long lasting viability of the cells expressing the polypeptide, while immobilizing the cells. Thereby the cells can be concentrated at preferred locations within the subject. For instance the cells can be transplanted subcutaneously and/or in proximity of diseased regions of the subject i.e. close to a vestibular schwannoma. It is surprising that by introducing encapsulated cells, the cells function particularly efficiently as bio pumps and provide a high level of therapeutic polypeptides to the subject. In a preferred embodiment the invention further relate to pharmaceutical composition for use as a medicament in the treatment of a disease associated with pathogenic long-lived plasma cells as described herein, wherein the pharmaceutical composition comprises the polypeptide, the nucleic acid, the gene therapy vector and/or the cell, and optionally a pharmaceutically accepted carrier. Preferably the pharmaceutical composition is administered to the subject at a therapeutically effective amount at any administration route as described herein.

In a preferred embodiment the pharmaceutical composition for use as a medicament as described herein is administered by introducing a therapeutically effective amount of the composition into the blood stream of a subject. This route of administration is particularly advantageous for an administration of the polypeptides.

In a further preferred embodiment the pharmaceutical composition for use as a medicament as described herein is administered locally. It is particularly preferred that the pharmaceutical composition is administered locally to the site of the pathogenic long-lived plasma cells, such as the bone marrow. It may also be preferred that the local administration of the pharmaceutical composition to the bone marrow is achieved by injecting the polypeptide or the pharmaceutical composition of the present invention.

Moreover in a preferred embodiment the local administration of the polypeptides may be preferably mediated by an implant such as a collagen sponge. To this end it may be preferred to soak the sponge in a pharmaceutical composition comprising the polypeptides and implant the sponge close to the site of the pathogenic long-lived plasma cells. By doing so the polypeptides advantageously diffuse locally and can therefore act site specifically.

In further preferred embodiment the polypeptides may be locally administered by means of a hydrogel. Hydrogels are three-dimensional, cross-linked networks of water-soluble polymers. The person skilled in the art knows how to produce suitable hydrogels for the delivery of proteins or polypeptides (Hoare et al. 2008, Peppas et al. 2000, Hoffmann A. et al. 2012). In particular the density of the cross-linked network of the hydrogel may be advantageously optimized to achieve a porosity suited to load the polypeptides into the hydrogel. Subsequently the release of the polypeptides is governed by the diffusion of the peptides throughout the gel network. Therefore the release rate and thus the therapeutically effective amount of the polypeptides can be precisely tuned by optimizing the cross-linking density of the hydrogel. Moreover preferred hydrogels may also encompass an outer membrane optimized for the release of the polypeptides. The preferred hydrogels are biocompatible and are preferably implanted for a long term local supply of the polypeptides. In preferred embodiments the hydrogels may be implanted

subcutaneously at or close to the site of the pathogenic long-lived plasma cells. Transdermal administration of the polypeptides by use of hydrogels may also be envisioned. By means hydrogels a therapeutically effective dose of polypeptides can be advantageously localized to the site of the pathogenic long-lived plasma cells, while minimizing the systemic dosage. Thereby a long term administration can be achieved with a sustained and site specific release and minimized side effects. As used herein, "nucleic acid" shall mean any nucleic acid molecule, including, without limitation, DNA, RNA and hybrids or modified variants thereof. An "exogenous nucleic acid" or "exogenous genetic element" relates to any nucleic acid introduced into the cell, which is not a component of the cells "original" or "natural" genome. Exogenous nucleic acids may be integrated or non- integrated, or relate to stably transfected nucleic acids.

As used herein, "polypeptide" shall mean both peptides and proteins. In this invention, the polypeptides may be naturally occurring or recombinant (i.e., produced via recombinant DNA technology), and may contain mutations (e.g., point, insertion and deletion mutations) as well as other covalent modifications (e.g., glycosylation and labelling (via biotin, streptavidin, fluorescein, and radioisotopes)) or other molecular bonds to additional components. For example, PEGylate proteins are encompassed by the scope of the present invention. PEGylation has been widely used as a post-production modification methodology for improving biomedical efficacy and physicochemical properties of therapeutic proteins. Applicability and safety of this technology have been proven by use of various PEGylated pharmaceuticals for many years (refer Jevsevar et al, Biotechnol J. 2010 Jan;5(1):1 13-28). In some embodiments the polypeptides described herein are modified to exhibit longer in vivo half-lives and resist degradation when compared to unmodified polypeptides. Such modifications are known to a skilled person, such as cyclized polypeptides, polypeptides fused to Vitamin B12, stapled peptides, protein lipidization and the substitution of natural L-amino acids with D-amino acids (refer Bruno et al, Ther Deliv. 2013 Nov; 4(1 1 ): 1443-1467).

In some embodiments of the invention the peptide, preferably according to sequences disclosed herein, may comprise a 0 to 10 amino acid addition or deletion at the N and/or C terminus of a sequence.

As used herein the term "a 0 to 10 amino acid addition or deletion at the N and/or C terminus of a sequence" means that the polypeptide may have a) 0, 1 , 2, 3, 4, 5, 6, 7, 8, 9 or 10 additional amino acids at its N terminus and 0, 1 , 2, 3, 4, 5, 6, 7, 8, 9 or 10 amino acids deleted at its C terminus or b) 0, 1 , 2, 3, 4, 5, 6, 7, 8, 9 or 10 additional amino acids at its C terminus and 0, 1 , 2, 3, 4, 5, 6, 7, 8, 9 or 10 nucleotides deleted at its N terminus, c) 0, 1 , 2, 3, 4, 5, 6, 7, 8, 9 or 10 additional amino acids at its N terminus and 0, 1 , 2, 3, 4, 5, 6, 7, 8, 9 or 10 additional amino acids at its N terminus or d) 0, 1 , 2, 3, 4, 5, 6, 7, 8, 9 or 10 amino acids deleted at its N terminus and 0, 1 , 2, 3, 4, 5, 6, 7, 8, 9 or 10 amino acids deleted at its C terminus.

Furthermore, in addition to the polypeptides described herein, peptidomimetics are also contemplated. Peptide analogs are commonly used in the pharmaceutical industry as non- peptide drugs with properties analogous to those of the template peptide. These types of non- peptide compound are termed "peptide mimetics" or "peptidomimetics" (Fauchere (1986) Adv. Drug Res. 15: 29; Veber and Freidinger (1985) TINS p. 392; and Evans et al. (1987) J. Med. Chem. 30: 1229) and are usually developed with the aid of computerized molecular modelling. Peptide mimetics that are structurally similar to therapeutically useful peptides may be used to produce an equivalent therapeutic or prophylactic effect. It may be preferred in some

embodiments to use peptide mimetics in order to prolong the stability of the polypeptides, when administered to a subject. To this end peptide mimetics for the polypeptides may be preferred that are not cleaved by human proteasomes.

The polypeptides, nucleic acid molecules, gene therapy vectors or cells described herein may comprise different types of carriers depending on whether they are to be administered in solid, liquid or aerosol form, and whether they need to be sterile for such routes of administration as injection.

The active agent of present invention can be administered intravenously, intradermally, intraarterially, intraperitoneally, intralesionally, intracranially, intraarticularly, intraprostaticaly, intrapleural^, intratracheally, intranasally, intravitreally, intravaginally, intrarectally, topically, intratumorally, intramuscularly, intraperitoneally, subcutaneously, subconjunctival,

intravesicularlly, mucosally, intrapericardially, intraumbilically, intraocularally, orally, topically, locally, inhalation (e.g., aerosol inhalation), injection, infusion, continuous infusion, directly, via a catheter, via a lavage, in cremes, in lipid compositions (e.g., liposomes), locally applied by sponges or by other method or any combination of the forgoing as would be known to one of ordinary skill in the art (see, for example, Remington's Pharmaceutical Sciences, 18th Ed. Mack Printing Company, 1990, incorporated herein by reference).

The present invention encompasses treatment of a patient by introducing a therapeutically effective number polypeptides, nucleic acids, gene therapy vectors or cells of the present invention into a subject's bloodstream. As used herein, "introducing" polypeptides, nucleic acids, gene therapy vectors or cells into the subject's bloodstream shall include, without limitation, introducing such polypeptides, nucleic acids, gene therapy vectors or cells into one of the subject's veins or arteries via injection. Such administering can also be performed, for example, once, a plurality of times, and/or over one or more extended periods. A single injection is preferred, but repeated injections over time (e.g., quarterly, half-yearly or yearly) may be necessary in some instances. Such administering is also preferably performed using an admixture of polypeptides, nucleic acids, gene therapy vectors or cells and a pharmaceutically acceptable carrier. Pharmaceutically acceptable carriers are well known to those skilled in the art and include, but are not limited to, 0.01-0.1 M and preferably 0.05 M phosphate buffer or 0.8% saline.

Administration may also occur locally, for example by injection into an area of the subject's body in proximity to a site where pathogenic long-lived plasma cells are localized. As used herein, in "proximity with" a tissue/site includes, for example, within 50 mm, 20 mm, 10 mm, 5 mm, within 1 mm of the tissue, within 0.5 mm of the tissue and within 0.25 mm of the tissue/site.

As used herein, "pharmaceutically acceptable carrier" includes any and all solvents, dispersion media, coatings, antibacterial and antifungal agents, isotonic and absorption delaying agents and the like. The use of such media and agents for pharmaceutical active substances is well known in the art. Except insofar as any conventional media or agent is incompatible with the active ingredient, its use in the therapeutic compositions is contemplated. Supplementary active ingredients can also be incorporated into the compositions. Additionally, such pharmaceutically acceptable carriers can be aqueous or non-aqueous solutions, suspensions, and emulsions, most preferably aqueous solutions. Aqueous carriers include water, alcoholic/aqueous solutions, emulsions and suspensions, including saline and buffered media. Parenteral vehicles include sodium chloride solution, Ringer's dextrose, dextrose and sodium chloride, lactated Ringer's and fixed oils. Intravenous vehicles include fluid and nutrient replenishers, electrolyte replenishers such as Ringer's dextrose, those based on Ringer's dextrose, and the like. Fluids used commonly for i.v. administration are found, for example, in Remington: The Science and Practice of Pharmacy, 20th Ed., p. 808, Lippincott Williams S- Wilkins (2000). Preservatives and other additives may also be present, such as, for example, antimicrobials, antioxidants, chelating agents, inert gases, and the like.

The phrase "pharmaceutically acceptable" refers to molecular entities and compositions that do not produce an allergic or similar untoward reaction when administered to a human. The preparation of an aqueous composition that contains a protein as an active ingredient is well understood in the art. Typically, such compositions are prepared as injectables, either as liquid solutions or suspensions; solid forms suitable for solution in, or suspension in, liquid prior to injection can also be prepared. The preparation can also be emulsified.

The composition can be formulated in a neutral or salt form. Pharmaceutically acceptable salts, include the acid addition salts (formed with the free amino groups of the protein) and which are formed with inorganic acids such as, for example, hydrochloric or phosphoric acids, or such organic acids as acetic, oxalic, tartaric, mandelic, and the like. Salts formed with the free carboxyl groups can also be derived from inorganic bases such as, for example, sodium, potassium, ammonium, calcium, or ferric hydroxides, and such organic bases as isopropylamine, trimethylamine, histidine, procaine and the like.

Upon formulation, solutions will be administered in a manner compatible with the dosage formulation and in such amount as is therapeutically effective. The formulations are easily administered in a variety of dosage forms such as injectable solutions, drug release capsules and the like.

As used herein, a "therapeutically effective amount" for the pharmaceutical composition includes, without limitation, the following amounts and ranges of amounts:

For a composition comprising a polypeptide according to the invention or preferred embodiment thereof: (i) from about 1 x 10 ^"3 to about 1 x 10 ⁶ μg kg body weight; (ii) from about 1 x 10 ^"2 to about 1 x 10 ⁵ μg kg body weight; (iii) from about 1 x 10 ^"1 to about 1 x 10 ⁴ μg kg body weight; (iv) from about 1 x 10 ^"1 to about 1 x 10 ³ μg kg body weight; (v) from about 1 x 10 ^"1 to about 1 x 10 ² μg kg body weight; (vi) from about 1 x 10 ^"1 to about 0.5 x 10 ² μg kg body weight; (vii) about 1 x 10 ^"2 μg kg body weight; (viii) about 1 x 10 ¹ μg kg body weight; (ix) about 10 μg kg body weight (x) about 1 x 10 ² μg kg body weight; (xi) about 5 x 10 ³ μg kg body weight.

For a composition comprising cells according to the invention or preferred embodiment thereof: (i) from about 1 x 10 ² to about 1 x 10 ⁸ cells/kg body weight; (ii) from about 1 x 10 ³ to about 1 x 10 ⁷ cells/kg body weight; (iii) from about 1 x 10 ⁴ to about 1 x 10 ⁶ cells/kg body weight; (iv) from about 1 x 10 ⁴ to about 1 x 10 ⁵ cells/kg body weight; (v) from about 1 x 10 ⁵ to about 1 x 10 ⁶ cells/kg body weight; (vi) from about 5 x 1 0 ⁴ to about 0.5 x 10 ⁵ cells/kg body weight; (vii) about 1 x 10 ³ cells/kg body weight; (viii) about 1 x 1 0 ⁴ cells/kg body weight; (ix) about 5 x 10 ⁴ cells/kg body weight; (x) about 1 x 1 0 ⁵ cells/kg body weight; (xi) about 5 x 10 ⁵ cells/kg body weight; (xii) about 1 x 1 0 ⁶ cells/kg body weight; and (xiii) about 1 x 1 0 ⁷ cells/kg body weight.

Human body weights envisioned include, without limitation, about 5 kg, 10 kg, 15 kg, 30 kg, 50 kg, about 60 kg; about 70 kg; about 80 kg, about 90 kg; about 100 kg, about 120 kg and about 150 kg.

Dosages of the viral gene therapy vector will depend primarily on factors such as the condition being treated, the selected gene, the age, weight and health of the patient, and may thus vary among patients. For example, a therapeutically effective human dosage of the viral vectors may be preferably in the range of from about 1 to about 1 000 ml, preferably 10 to 100 ml, preferably 20 to 50 ml of saline solution containing concentrations of from about 1 x 10 ⁵ to 1 x 1 0 ¹² preferably 1 x 10 ⁶ to 1 x 1 0 ¹¹ more preferably 1 x 1 0 ⁷ to 1 x 1 0 ¹⁰ plaque forming units (pfu)/ml viruses. The dosage will be adjusted to balance the therapeutic benefit against any side effects. The levels of expression of the selected gene can be monitored to determine the selection, adjustment or frequency of dosage administration.

As used herein "inducible expression" or "conditional expression" relates to a state, multiple states or system of an expression of the polypeptide, wherein the polypeptide is preferably not expressed, or in some embodiments expressed at negligible or relatively low levels, unless there is the presence of one or more molecules (an inducer) or other set of conditions in the cell that allows for polypeptide expression. Inducible promoters may relate to either naturally occurring promoters that are expressed at a relatively higher level under particular biological conditions, or to other synthetic promoters comprising any given inducible element. Inducible promoters may refer to those induced by particular tissue- or micro-environments or combinations of biological signals present in particular tissue- or micro-environments, or to promoters induced by external factors, for example by administration of a small drug molecule or other externally applied signal.

As used herein the term "bio pump" or "drug factory" preferably describe the function of cells as a continuously producing source of the polypeptide, preferably at a therapeutically effective dosage. By administering cells to a subject particularly stable levels of the polypeptides according to the invention or preferred embodiments thereof can be provided. In the sense the bio pump, that is the cells, allow for a continuous supply that maintain levels of the polypeptides at a particular high and stable state, for example it may compensate for losses of the polypeptides for instance due to a degeneration of the polypeptides through proteasomes.

The terms "hydrogel", "gel" and the like, are preferably used interchangeably herein to refer to a material which is not a readily flowable liquid and not a solid. The term hydrogel is preferably meant to be a water insoluble, water-containing material. Examples of hydrogels include synthetic polymers such as polyhydroxyethyl methacrylate, poly(ethylene glycol) and chemically or physically crosslinked polyvinyl alcohol, polyacrylamide, poly(N-vinyl pyrolidone), polyethylene oxide, and hydrolysed polyacrylonitrile. Examples of hydrogels which are organic polymers include DNA hydrogels or covalent or ionically crosslinked polysaccharide-based hydrogels such as the polyvalent metal salts of alginate, pectin, carboxymethyl cellulose, heparin, hyaluronate and hydrogels from chitin, chitosan, pullulan, gellan and xanthan.

Plasma cells, are also called plasma B cells, plasmocytes, plasmacytes, or effector B cells.

Plasma cells are white blood cells / immune cells that secrete large volumes of antibodies.

Plasma cells are transported by the blood plasma and the lymphatic system and originate in the bone marrow; B cells differentiate into plasma cells that produce antibody molecules. Once released into the blood and lymph, these antibody molecules bind to the target antigen (foreign substance) and initiate its neutralization or destruction by means of the immune system. B cells can differentiate into memory B cells or plasma cells upon stimulation, mostly by T cells, which usually occurs in germinal centers of secondary lymphoid organs like the spleen and lymph nodes. Most of these B cells will become plasmablasts (or "immature plasma cells"), and eventually plasma cells, and begin producing large volumes of antibodies, while some B cells will undergo affinity maturation, which refers to the selection of antibodies with higher affinity for the antigen and the activation and growth of B cell clones able to secrete antibodies of higher affinity. After the process of affinity maturation in germinal centers, plasma cells have an indeterminate lifespan, ranging from days to months. A specific subclass of plasma cells has been shown to reside for much longer periods in the bone marrow. This class of plasma cells is referred to as "long-lived plasma cells" (LLPC). LLPC secrete high levels of antibodies, wherein LLPC comprise, without limitation, IgM-secreting LLPC, IgG-secreting LLPC, IgA-secreting LLPC and IgE- secreting LLPC. Furthermore, LLPC cannot switch antibody classes and cannot act as antigen- presenting cells. LLPC constitute an independent component of immunological memory. They are generated in the context of memory immune reactions and migrate to the bone marrow, where they persist for years and decades. Their survival is dependent on receiving distinct signals provided by cells forming a plasma cell survival niche. Displacement of a plasma cell or long-lived plasma cell from the survival niche might result in apoptosis of the cell.

Long-lived plasma cells survive in a protected microenvironment for years or even a lifetime and provide humoral memory by establishing persistent Ab titers. The term "pathogenic long-lived plasma cell" refers to long-lived plasma cells, which may be for example autoreactive, malignant, and allergen-specific long-lived plasma cells. These pathogenic long-lived plasma cell are likewise protected in their survival niche and are refractory to immunosuppression, B cell depletion, and irradiation. Their elimination remains an essential therapeutic challenge. As a consequence of their longevity and persistence, long-lived plasma cells can support chronic inflammatory processes in autoimmune diseases by continuously secreting pathogenic antibodies, and they can contribute to flares of symptoms.

Accordingly, the term "disease associated with pathogenic long-lived plasma cells" refers to, without limitation, plasma cell associated cancerous malignancies, such as plasmacytoma, multiple myeloma, Waldenstrom macroglobulinemia, Lymphoplasmacytic lymphoma (LPL), POEMS syndrome / osteosclerotic myeloma, Type I and II cryoglobulinemia, Primary Amyloidosis (AL), Heavy chain disease, Monoclonal gammopathy of undetermined significance (MGUS) and plasma cell leukemia; auto-antibody associated autoimmune diseases, such as rheumatoid arthritis, systemic lupus erythematosus (SLE), chronic immune thrombocytopenia, Sjogren's syndrome, or multiple sclerosis; and allergies through, for example, LLPCs that produce allergen- specific IgE antibodies. A skilled person is aware of diseases falling under this category and furthermore can determine these disease by employing established immunologic methods to interrogate long-lived plasma cells and their pathogenicity.

According to a preferred embodiment of the invention, the pathogenic long-lived plasma cells interact with laminin βΐ -positive stroma cells. Laminin βΐ -positive stroma cells are stroma cells that can be identified as stroma cells that co-localize with laminin β1 , for example in an microscopic analysis by immunofluorescence.

Laminin β1 is a member of the family of laminin proteins, which are extracellular matrix glycoproteins, which are a major noncollagenous constituent of basement membranes. They have been implicated in a variety of processes including cell adhesion, differentiation, migration, signalling and metastasis. Laminins are composed of 3 non-identical chains: laminin alpha, beta and gamma (formerly A, B1 , and B2, respectively). Each laminin chain is a multidomain protein encoded by a distinct gene. Several isoforms of each chain have been described. Different alpha, beta and gamma chain isomers combine to give rise to different heterotrimeric laminin isoforms, for example the alpha1 -beta1 -gamma1 heterotrimer is laminin 1 . The beta chain isoform laminin β1 has 7 structurally distinct domains, which it shares with other beta chain isomers. Laminin, beta 1 is expressed in most tissues that produce basement membranes, and is one of the 3 chains constituting laminin 1 . A sequence in the beta 1 chain that is involved in cell attachment, chemotaxis, and binding to the laminin receptor was identified and shown to have the capacity to inhibit metastasis.

The term "stroma cells" refers to various cells types that constitute the stroma of a tissue. The stroma is the part of a tissue or organ that has a connective and structural role. It consists of all the parts, which do not carry out the specific functions of the organ, for example, connective tissue, blood vessels, nerves, ducts, etc. The other part, the parenchyma, consists of the cells that perform the function of the tissue or organ. The stroma of the bone marrow is all tissue not directly involved in the bone marrow's primary function of hematopoiesis. The stroma of the bone marrow is indirectly involved in hematopoiesis, since it provides the hematopoietic

microenvironment that facilitates hematopoiesis, for example by generating factors such as colony stimulating factors, which have a significant effect on hematopoiesis. Cell types that are comprised by the bone marrow stroma include, without limitation, fibroblasts (reticular connective tissue), macrophages, adipocytes, osteoblasts, osteoclasts and endothelial cells, which form the sinusoids, and endothelial stem cells.

Multiple myeloma is a B cell malignancy of mature plasma cell morphology characterized by the neoplastic transformation of a single clone of these types of cells. These plasma cells proliferate in BM and may invade adjacent bone and sometimes the blood. Variant forms of multiple myeloma include overt multiple myeloma, smoldering multiple myeloma, plasma cell leukemia, non-secretory myeloma, IgD myeloma, osteosclerotic myeloma, solitary plasmacytoma of bone, and extramedullar Plasmacytoma.

Auto-antibody associated autoimmune diseases that can be associated with pathogenic long- lived plasma cells and are comprised the diseases associated with long-lived plasma cells is preferably selected from Takayasu Arteritis, Giant-cell arteritis, familial Mediterranean fever, Kawasaki disease, Polyarteritis nodosa, cutanous Polyarteritis nodosa, Hepatitis-associated arteritis, Behcet's syndrome, Wegener's granulomatosis, ANCA-vasculitidies, Churg-Strauss syndrome, microscopic polyangiitis, Vasculitis of connective tissue diseases, Hennoch-Schonlein purpura, Cryoglobulinemic vasculitis, Cutaneous leukocytoclastic angiitis, Tropical aortitis, Sarcoidosis, Cogan's syndrome, Wiskott-Aldrich Syndrome, Lepromatous arteritis, Primary angiitis of the CNS, Thromboangiitis obliterans, Paraneoplastic ateritis, Urticaria, Dego's disease, Myelodysplasia syndrome, Eythema elevatum diutinum, Hyperimmunoglobulin D, Allergic Rhinitis, Asthma bronchiale, chronic obstructive pulmonary disease, periodontitis, Rheumatoid Arthritis, atherosclerosis, Amyloidosis, Morbus Chron, Colitis ulcerosa, Autoimmune Myositis, Diabetes mellitus, Guillain-Barre Syndrome, histiocytosis, Osteoarthritis, atopic dermatitis, periodontitis, chronic rhinosinusitis, Psoriasis, psoriatic arthritis, Microscopic colitis, Pulmonary fibrosis, glomerulonephritis, Whipple's disease, Still's disease, erythema nodosum, otitis, cryoglobulinemia, Sjogren's syndrome, Lupus erythematosus, preferably systemic lupus erythematosus (SLE), aplastic anemia, Osteomyelofibrosis, chronic inflammatory demyelinating polyneuropathy, Kimura's disease, systemic sclerosis, chronic periaortitis, chronic prostatitis, idiopathic pulmonary fibrosis, chronic granulomatous disease, Idiopathic achalasia, bleomycin- induced lung inflammation, cytarabine-induced lung inflammation, Autoimmunthrombocytopenia, Autoimmunneutropenia, Autoimmunhemolytic anemia, Autoimmunlymphocytopenia, Chagas' disease, chronic autoimmune thyroiditis, autoimmune hepatitis, Hashimoto's Thyroiditis, atropic thyroiditis, Graves disease, Autoimmune polyglandular syndrome, Autoimmune Addison

Syndrome, Pemphigus vulgaris, Idiopathic thrombocytopenic purpura (ITP), Light chain deposition disease, Acute glomerulonephritis, Pemphigus and Pemphigoid disorders, and Epidermolysis bullosa acquisita, Pemphigus foliaceus, Dermatitis herpetiformis, Autoimmune alopecia, Vitiligo, Antiphospholipid syndrome, Myasthenia gravis, Stiff-man syndrome,

Goodpasture's syndrome, Sympathetic ophthalmia, Folliculitis, Sharp syndrome and/or Evans syndrome, in particular hay fever, periodontitis, atherosclerosis, rheumatoid arthritis.

Systemic lupus erythematosus (SLE), also known as lupus, is an autoimmune disease in which the body's immune system attacks healthy tissue in various parts of the body. Symptoms vary between people and may be mild to severe. Common symptoms include painful and swollen joints, fever, chest pain, hair loss, mouth ulcers, swollen lymph nodes, feeling tired, and a red rash which is most commonly on the face.

Diseases associated with pathogenic long-lived plasma cells may also comprise B cell non- Hodgkin lymphoma, such as Burkitt lymphoma, chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL), diffuse large B cell lymphoma, follicular lymphoma, immunoblastic large cell lymphoma, precursor B-lymphoblastic lymphoma, and mantle cell lymphoma.

As used herein, "treatment" of a disease or "treating" a subject afflicted with a disorder shall mean slowing, stopping or reversing the disorder's progression. In the preferred embodiment, treating a subject afflicted with a disorder means reversing the disorder's progression, ideally to the point of eliminating the disorder itself. As used herein, ameliorating a disorder and treating a disorder are equivalent. The treatment of the present invention may also, or alternatively, relate to a prophylactic administration of the active agents described herein. Such a prophylactic administration may relate to the prevention of any given medical disorder, or the prevention of development of said disorder, whereby prevention or prophylaxis is not to be construed narrowly under all conditions as absolute prevention. Prevention or prophylaxis may also relate to a reduction of the risk of a subject developing any given medical condition, preferably in a subject at risk of said condition.

According to a preferred embodiment of the present invention, the treatment comprises the combined administration of said polypeptide with an anti-B cell therapy, an immunosuppressive drug, an anti-tumor therapy or an anti-tumor chemotherapy.

"Combined administration" may relate to concurrent and/or sequential administration of said polypeptide prior to, during and/or subsequent to said anti-B cell therapy, immunosuppressive drug and/or anti-tumor chemotherapy. Combined treatment shall also include a combination treatment regime comprising multiple administrations of either therapeutic component of the treatment. Further embodiments of combined administration are provided herein.

Combined administration encompasses simultaneous treatment, co-treatment or joint treatment, and includes the administration of separate formulations of the polypepdide of the present invention with an anti-B cell therapy, an immunosuppressive drug or an anti-tumor chemotherapy, whereby treatment may occur within minutes of each other, in the same hour, on the same day, in the same week or in the same month or within 3 months as one another. Sequential

administration of any given combination of combined agents is also encompassed by the term "combined administration". A combination medicament, comprising one or more of said polypeptide with an anti-B cell therapy, an immunosuppressive drug and/or an anti-tumor chemotherapy, may also be used in order to co-administer the various components in a single administration or dosage.

Anti-tumor therapies (or anti-cancer therapies) of the present invention comprise, without limitation, surgery, chemotherapy, radiotherapy, irradiation therapy, hormonal therapy, targeted therapy, immunotherapy, cell therapy and immune cell therapy.

The term "anti-B cell therapy" refers to therapeutic approaches or compounds that are directed against B cells or pathogenic B cells, for example in the context of B cell mediated disease. B cell specific therapies known to a person skilled in the art and also the novel developments in the field with respect to recent advances are being monitored by the skilled person, so that suitable anti-B cell therapies can be identified. Anti-B cell therapies comprise, without limitation, antibodies and monoclonal antibodies and cell therapeutic agents that are directed against B cell antigens, such as the anti-CD20 monoclonal antibody Rituximab and anti-CD19 CAR T cells or B cell depletion.

In the context of the present invention, chemotherapy refers to a category of cancer treatment that uses one or more anti-cancer drugs (chemotherapeutic agents) as part of a chemotherapy regimen. Chemotherapy may be given with a curative intent (which almost always involves combinations of drugs), or it may aim to prolong life or to reduce symptoms (palliative

chemotherapy). Chemotherapy is one of the major categories of medical oncology (the medical discipline specifically devoted to pharmacotherapy for cancer). Chemotherapeutic agents are used to treat cancer and are administered in regimens of one or more cycles, combining two or more agents over a period of days to weeks. Such agents are toxic to cells with high proliferative rates such as cancer or tumor cells.

Chemotherapeutic agents comprise, without limitation, Actinomycin, All-trans retinoic acid, Azacitidine, Azathioprine, Bleomycin, Bortezomib, Carboplatin, Capecitabine, Cisplatin,

Chlorambucil, Cyclophosphamide, Cytarabine, Daunorubicin, Docetaxel, Doxifluridine,

Doxorubicin, Epirubicin, Epothilone, Etoposide, Fluorouracil, Gemcitabine, Hydroxyurea,

Idarubicin, Imatinib, Irinotecan, Mechlorethamine, Mercaptopurine, Methotrexate, Mitoxantrone, Oxaliplatin, Paclitaxel, Pemetrexed, Teniposide, Tioguanine, Topotecan, Valrubicin, Vinblastine, Vincristine, Vindesine, Vinorelbine.

Irradiation or radiation therapy or radiotherapy in the context of the present invention relates to a therapeutic approach using ionizing or ultraviolet-visible (UV Vis) radiation, generally as part of cancer treatment to control or kill malignant cells such as cancer cells or tumor cells. Radiation therapy may be curative in a number of types of cancer, if they are localized to one area of the body. It may also be used as part of adjuvant therapy, to prevent tumor recurrence after surgery to remove a primary malignant tumor (for example, early stages of breast cancer). Radiation therapy is synergistic with chemotherapy, and can been used before, during, and after chemotherapy in susceptible cancers. Radiation therapy is commonly applied to the cancerous tumor because of its ability to control cell growth. Ionizing radiation works by damaging the DNA of cancerous tissue leading to cellular death. Radiation therapy can be used systemically or locally.

In the context of the present invention, immunosuppressive drugs refer to a class of drugs that suppress, or reduce, the strength of the body's immune system. Some of these drugs are used to make the body less likely to reject a transplanted organ, other immunosuppressant drugs are often used to treat autoimmune disorders. The person skilled in the art is able to identify suitable immunosuppressive drugs. Immunosuppressive drugs comprise, without limitation,

corticosteroids, such as prednisone (Deltasone, Orasone), budesonide (Entocort EC), prednisolone (Millipred); Calcineurin inhibitors, such as cyclosporine (Neoral, Sandimmune, SangCya), tacrolimus (Astagraf XL, Envarsus XR, Prograf); mTOR inhibitors such as sirolimus (Rapamune), everolimus (Afinitor, Zortress); IMDH inhibitors, such as azathioprine (Azasan, Imuran), leflunomide (Arava), mycophenolate (CellCept, Myfortic); Biologies such as abatacept (Orencia), adalimumab (Humira), anakinra (Kineret), certolizumab (Cimzia), etanercept (Enbrel), golimumab (Simponi), infliximab (Remicade), ixekizumab (Taltz), natalizumab (Tysabri), rituximab (Rituxan), secukinumab (Cosentyx), tocilizumab (Actemra), ustekinumab (Stelara), vedolizumab (Entyvio); Monoclonal antibodies such as basiliximab (Simulect), daclizumab (Zinbryta), muromonab (Orthoclone OKT3).

The present invention also relates to a mutant nontyphoidal Salmonella (NTS) bacterium for use as a vaccine in the prevention of a NTS infection in a subject, wherein the mutant NTS bacterium does not express a polypeptide comprising or consisting of a polypeptide of the present invention.

In the context of the present invention, a "mutant" bacterium is a bacterium that carries genetic alteration in comparison to the "wild-type", unmodified reference bacterium. Genetic alteration or mutations comprise insertions and deletions genetic material. Mutations may be spontaneous, due to error-prone replication bypass of naturally occurring DNA damage (also called error-prone translesion synthesis), due to errors introduced during DNA repair, or due to induction by mutagens. Also, mutations may be deliberately introduced through genetic manipulation.

A deletion of genetic material is a mutation (a genetic aberration or alteration) in which a part of a chromosome or a sequence of DNA is lost, for example during DNA replication or through genetic engineering. Any number of nucleotides can be deleted, from a single base to several megabases or an entire piece of chromosome. Deletions that do not occur in multiples of three bases can cause a frameshift by changing the 3-nucleotide protein reading frame of the genetic sequence.

In the context of the present invention, a "deletion of the SiiE encoding gene" can refers deletions of the entire genetic material or parts of the genetic material of a NTS bacterium encoding SiiE, wherein the expression of the protein by the NTS bacterium is prevented. Such deletions can also occur as mutations that prevent expression of SiiE, such as small deletions or even insertions of bases that lead to frame shift mutations leading to deletion of SiiE expression.

Salmonella serotypes can be divided into two main groups - typhoidal and nontyphoidal

Salmonella.

Nontyphoidal serotypes comprise invasive and non-invasive nontyphoidal Salmonella.

Nontyphoidal serotypes are more common, and usually cause self-limiting gastrointestinal disease. They can infect a range of animals, and are zoonotic, meaning they can be transferred between humans and other animals.

Infection with nontyphoidal serotypes (NTS) of Salmonella generally causes food poisoning, wherein infants and young children are much more susceptible to infection. The organisms usually enter through the digestive tract, while inhalation might also lead to infection. Upon entry into the small intestine, the bacteria multiply in tissues and mostly cause gastrointestinal diseases such as enteritis. About 2,000 serotypes of nontyphoidal Salmonella are known to a person skilled in the art.

Invasive strains of nontyphoidal Salmonellae have emerged as a prominent cause of bloodstream infection in African adults and children, with an associated case fatality of 20-25%, and include Salmonella enterica serovar Typhimurium. The clinical presentation of invasive non-typhoidal Salmonella disease in Africa is diverse: fever, hepatosplenomegaly, and respiratory symptoms are common, and features of enterocolitis are often absent. Most cases of invasive nontyphoidal Salmonella infection (iNTS) are caused by S. typhimurium or S. enteritidis. A new form of Salmonella typhimurium (ST313) emerged in the southeast of the African continent 75 years ago. The most important risk factors are HIV infection in adults, and malaria, HIV, and malnutrition in children.

Typhoidal serotypes of Salmonella cause Typhoid fever, are strictly adapted to humans or higher primates and include Salmonella Typhi, Paratyphi A, Paratyphi B and Paratyphi C. In the systemic form of the disease, Salmonellae pass through the lymphatic system of the intestine into the blood of the patients (typhoid form) and are carried to various organs (liver, spleen, kidneys) to form secondary foci (septic form). Endotoxins first act on the vascular and nervous apparatus, resulting in increased permeability and decreased tone of the vessels, upset of thermal regulation, and vomiting and diarrhoea. In severe forms of the disease, enough liquid and electrolytes are lost to upset the water-salt metabolism, decrease the circulating blood volume and arterial pressure, and cause hypovolemic shock. Septic shock may also develop. Shock of mixed character (with signs of both hypovolemic and septic shock) is more common in severe salmonellosis. Oliguria and azotemia may develop in severe cases as a result of renal involvement due to hypoxia and toxemia.

The term "vaccine" in the context of the present invention relates to a biological preparation that provides active acquired immunity to a particular disease, such as cancer, a pathogen or an infectious agent, such as bacteria or viruses. A vaccine can contain an agent or antigen that resembles or is derived from a disease-causing microorganism. Vaccines can be made from weakened, attenuated, mutated or killed forms of the pathogen, its toxins or one of its surface proteins. The agent stimulates the body's immune system to recognize the agent as a threat, destroy it, and recognize and destroy any pathogens or structures comprising the agent or antigen of the vaccine that it later encounters. Vaccines can be prophylactic (example: to prevent or ameliorate the effects of a future infection by a natural or "wild" pathogen), or therapeutic, such as specific cancer vaccines.

In a preferred embodiment of NTS bacterium for use as a vaccine in the present invention, the subject is a human, galliformes, cattle, sheep, swine, horse or rodent. Galliformes is an order of heavy-bodied ground-feeding birds that includes turkey, grouse, chicken, New World quail and Old World quail, ptarmigan, partridge, pheasant, junglefowl and the Cracidae. Cattle, or cows, are raised livestock for meat (beef and veal), as dairy animals for milk and other dairy products. The term "swine" refers to domestic pigs. Rodents are mammals, which are characterized by a single pair of continuously growing incisors in each of the upper and lower jaws. Well-known rodents include mice, rats, squirrels, prairie dogs, porcupines, beavers, guinea pigs, hamsters, gerbils and capybaras.

FIGURES

The invention is further described by the following figures. These are not intended to limit the scope of the invention, but represent preferred embodiments of aspects of the invention provided for greater illustration of the invention described herein.

Brief description of the figures:

Figure 1. Salmonella expands in the spleen and liver.

Figure 2. Numerical reduction of BM IgG-secreting plasma cells by intraperitoneal infection with Salmonella.

Figure 3. Wild-type Salmonella reduces BM IgG-secreting plasma cells.

Figure 4. Numerical reduction of BM IgG-secreting plasma cells by oral infection with Salmonella.

Figure 5. Identification of the microbial component reducing numbers of BM IgG-secreting plasma cells.

Figure 6. SHE has a high homology with conserved sequence of laminin β1.

Figure 7. Distribution of Salmonella and SHE in the spleen of Sa/mone//a-infected mice. Figure 8. BM IgG-secreting plasma cells persist in laminin β1 + CXCL12-expressing stromal cells. Figure 9. Splenic plasma cells do not contact laminin β1.

Figure 10. Potential receptors of laminin on plasma cells.

Figure 11. Microbiological feature of Salmonella enterica serovar Typhimurium strains, ΔΙ_οη and ALonASiiE.

Figure 12. Loss of SiiE enhances humoral immune response against Salmonella.

Figure 13. Salmonella reduces numbers of BM IgG-secreting plasma cells in a CXCL12- independent manner.

Figure 14. Salmonella does not affect the expression of adhesion molecules and survival factors for plasma cells.

Figure 15. SNE129 peptide reduce numbers of DNA-specific IgG-secreting plasma cells in the bone marrow.

Detailed description of the figures:

Figure 1. Salmonella expands in the spleen and liver. C57BL/6 mice were infected i.p. with 104 CFU of attenuated Salmonella and were sacrificed on the days indicated. Salmonella in the spleen and liver was counted. The data are representative of two independent experiments. n=3- 6.

Figure 2. Numerical reduction of BM IgG-secreting plasma cells by intraperitoneal infection with Salmonella. (A) Salmonella reduces numbers of IgG-secreting cells in the BM. C57BL/6 mice were infected intraperitoneal^ (i.p.) with 104 CFU of attenuated Salmonella and were sacrificed on day 4 after infection. Cells in the spleen and femurs of Sa/mone//a-infected (Inf) or uninfected (Uninf) mice were analyzed for IgM- or IgG-secreting cells by ELISpot assay. Photos show ELISpot data from IgG-secreting cells in the BM of infected or uninfected mice. n=10. (B) Salmonella reduces numbers of Blimp-1 +lgM- cells in the BM. Blimpgfp mice were infected i.p. with 104 CFU of attenuated Salmonella and were sacrificed on day 4 after infection. BM cells were analyzed by flow cytometry for the expression of IgA and Blimp-1 in Blimp-1 +CD138+B220- IgM-lgA- cells. Percentages show the frequencies of Blimp-1 +CD138+B220-lgM- cells in total live cells. n=4. (C) Salmonella numerically reduces intracellular (ic) lgG+ plasma cells in the BM. C57BL/6 mice were infected i.p. with 104 CFU of attenuated Salmonella and were sacrificed on day 4 after infection. BM cells were analyzed by flow cytometry for the expression of intracellular IgG in B220-CD138+ cells. n=6. (D) Salmonella reduces IgG titers in serum. Sera of Salmonella- infected and uninfected mice on day 7 post infection were analyzed for titers of total IgM and IgG by ELISA. n=4. The data are representative of at least two independent experiments. ^* p<0.05, ^** p<0.01 , ^*** p<0.001 , n.s. not significant.

Figure 3. Wild-type Salmonella reduces BM IgG-secreting plasma cells. Mice were infected with Salmonella wild-type strain and on day 5 were analyzed for IgG-secreting plasma cells by ELISpot assay. n=6-7. The data are representative of two independent experiments. ^*** p<0.001.

Figure 4. Numerical reduction of BM IgG-secreting plasma cells by oral infection with Salmonella. C57BL/6 mice were infected orally with 107 CFU of attenuated Salmonella and were analyzed on day 7. Cells from the spleen, femurs and lamina propia from infected or uninfected mice were analyzed for IgM- or IgG- and IgA-secreting cells by ELISpot assay. n=7. The data are representative of two independent experiments. ^* p<0.05.

Figure 5. Identification of the microbial component reducing numbers of BM IgG-secreting plasma cells. (A) Salmonella colonizes in the spleen and liver but not in the BM. The CFU of Salmonella in the spleen, liver and BM of Sa/mone//a-infected mice on day 4 after infection was counted. The dotted line represents the limit of detection. n=3-6. (B) Sa/mone//a-specific microbial component reduces numbers of BM IgG-secreting plasma cells. C57BL/6 mice received 200 μΙ of LB medium, untreated or LPS-depleted culture supernatants from flagellin-deficient attenuated Salmonella or Escherichia coli (ALonAFIhD) and on the next day (24 h later) were analyzed for IgG-secreting cells by ELISpot assay. n=8. (C) Supernatant from attenuated Salmonella reduces numbers of antigen-specific IgG-secreting plasma cells in the BM. C57BL/6 mice were primed i.p. with 100 μg of NP-CGG/IFA (day 0) and were boosted with 50 μg of NP-CGG 4 weeks after priming (day 28). Mice were infected i.p. with 200 μΙ of LB and LPS-depleted supernatant from flagellin-deficient attenuated Salmonella on day 41 and analyzed for IgG-secreting cells on the next day. n=6. (D) Supernatant from SiiE-deficient attenuated Salmonella fails to reduce BM IgG- secreting plasma cell numbers. C57BL/6 mice received i.p. 200 μΙ of LB medium and LPS- depleted supernatants from attenuated Salmonella ALon or ALonASiiE and on the next day were analyzed for IgG-secreting cells by ELISpot assay. n=5. (E) Forty amino acid-peptide from the N terminus of SiiE protein reduces numbers of BM IgG-secreting plasma cells. C57BL/6 mice received i.p. 100 μg peptide coding SiiE amino acid 129-168 and on the next day were analyzed for IgG- and IgM-secreting cells in the BM and spleen. n=5. (F) SiiE fragment binds to IgG- secreting plasma cells in the BM but not spleen. BM or splenic cells from C57BL/6 mice were incubated with 30 μg ml of GST-SiiE 97-170 or GST protein, stained with anti-GST antibodies, and analyzed by flow cytometry. n=3. (G) SiiE fragment inhibits the adhesion of BM IgG-secreting plasma cells to laminin in vitro. Sorted CD138+B220-lgM-lgA- cells from the BM of C57BL/6 mice were treated with GST-SiiE 97-170 or GST protein and incubated with laminin-coated plates. Adherent cells were counted after washing. The data are representative of at least two independent experiments. ^* p<0.05, ^*** p<0.001 .

Figure 6. SiiE has a high homology with conserved sequence of laminin β1.

Figure 7. Distribution of Salmonella and SiiE in the spleen of Sa/mone//a-infected mice. Splenic frozen sections from C57BL/6 mice infected with Salmonella ALon or ALonASiiE were stained for Salmonella and SiiE protein. The data are representative of two independent experiments.

Figure 8. BM IgG-secreting plasma cells persist in laminin β1 + CXCL12-expressing stromal cells. (A) The distribution of laminin β1 on CXCL12+ stromal cells in the BM. BM frozen sections from CXCL12/GFP knock-in mice were stained for laminin β1 . (B) IgG- but not IgM-secreting plasma cells contact laminin β1. BM frozen sections from Blimpgfp mice were stained for laminin β1 and IgG or IgM. Bar graph shows the percentages of laminin βΐ-bound lg+ plasma cells in total lg+ plasma cells. n=80-100 (3 mice). (C) lgG+ cells contact laminin β1 +ΟΧΟί12+ stromal cells in the BM. BM frozen sections from CXCL12/GFP knock-in mice were stained for laminin β1 and IgG. The data are representative of two independent experiments.

Figure 9. Splenic plasma cells do not contact laminin β1. Splenic frozen sections from Blimpgfp mice were stained for laminin β1 and IgG or IgM. Bar graph shows the percentages of laminin β1 - bound lg+ plasma cells in total lg+ plasma cells. n=50. The data are representative of two independent experiments. Figure 10. Potential receptors of laminin on plasma cells. BM and splenic cells from Blimpgfp mice were analyzed for the expression of each laminin receptors on Blimp-1 +CD138+B220- IgM- or lgM+ plasma cells. Staining with isotype control is shown in grey. n=3. The data are representative of two independent experiments.

Figure 11. Microbiological feature of Salmonella enterica serovar Typhimurium strains, ΔΙ_οη and ALonASiiE. (A) Growth curve of strains ΔΙ_οη (circle) and ALonASiiE (square). (B) SDS-12.5% PAGE pattern of secreted proteins in the culture supernatants prepared from strains ΔΙ_οη (lane 1 ) and ALonASiiE (lane 2). Lane M contains low molecular mass standards. The data are representative of two independent experiments.

Figure 12. Loss of SiiE enhances humoral immune response against Salmonella. (A) SiiE- deficient attenuated Salmonella normally expands in the spleen. C57BL/6 mice were infected i.p. with 104 CFU of SiiE-deficient (ALonASiiE) or SiiE-abundant (ALon) attenuated Salmonella and 4 days later were analyzed for CFU of Salmonella in the spleen and BM. The dotted line represents the limit of detection. n=6. (B) SiiE-deficient Salmonella enhances the provision of anti- Salmonella antibodies. C57BL/6 mice were infected i.p. with 104 CFU of attenuated Salmonella ALonASiiE or ALon, were bled on days 7, 14, 21 and 42 after infection, and were analyzed for a W-Salmonella IgG by ELISA. n=6. (C) Vaccination of SiiE-deficient attenuated Salmonella efficiently protects against a lethal dose of Salmonella. C57BL/6 mice which were vaccinated i.p. with 104 CFU of attenuated Salmonella ALonASiiE or ALon, were challenged i.p. with 103 CFU of wild-type Salmonella on day 21 after vaccination. On day 28, the number of Salmonella in the spleen of the infected mice was enumerated. n=5. The data are representative of at least two independent experiments. ^** p<0.01 , ^*** p<0.001 .

Figure 13. Salmonella reduces numbers of BM IgG-secreting plasma cells in a CXCL12- independent manner. C57BL/6 mice were infected i.p. with 104 CFU of attenuated Salmonella and were sacrificed on day 4 post infection. Cells in the BM (A), spleen (B) and blood (C) were stained with antibodies against B220, IgM and IgD and were analyzed by flow cytometry. n=4-6. (D-F) Salmonella reduces the expression of CXCL12 in the BM. CXCL12/GFP knock-in mice were infected i.p. with 104 CFU of attenuated Salmonella and on day 4 were analyzed for the expression of CXCL12 by histology (D), quantitative RT-PCR (E, whole BM) and flow cytometry as CXCL12+CD45-Ter1 19-PECAM-1 -PI- cells (F). n=3. (G) Salmonella does not affect the expression of CXCR4 on intracellular lgG+ plasma cells. Mean fluorescent intensity (MFI) of CXCR4 on lgG+ plasma cells of infected or uninfected mice on day 4 is shown. n=3. (H and I) AMD3100 numerically reduces B cells but not IgG-secreting plasma cells in the BM. C57BL/6 mice were injected i.p. twice a day with 5 μg of AMD3100 for 4 days. B220+ cells and IgG- secreting plasma cells were analyzed on day 4 by flow cytometry (H) and by ELISpot assay (I), respectively. n=5-6. The data are representative of at least two independent experiments.

*p<0.05, ^** p<0.01 , ^*** p<0.001.

Figure 14. Salmonella does not affect the expression of adhesion molecules and survival factors for plasma cells. C57BL/6 mice were infected i.p. with 104 attenuated Salmonella and on day 4 were analyzed for the distribution of VCAM-1 and fibronectin by histological analysis (A), for the expression of integrin a4, CD44 and BCMA on BM intracellular lgG+ plasma cells by flow cytometry (B-D), and for the expression of APRIL and Galectin-1 in the whole BM by quantitative RT-PCR (E and F). n=3. The data are representative of two independent experiments. Figure 15. Forty amino acid-peptide from the N terminus of SHE protein reduces numbers of anti- DNA IgG-secreting plasma cells in the BM. NZB W F1 female mice (5-6 months old) received i.p. 100 μg peptide coding SiiE amino acid 129-168 on days 0, 3, 7 and 10 and on day 1 1 were analyzed for anti-DNA IgG-secreting cells in the BM by ELISpot assay. n=5-6. The data are representative of two independent experiments.

EXAMPLES

The invention is further described by the following examples. These are not intended to limit the scope of the invention, but represent preferred embodiments of aspects of the invention provided for greater illustration of the invention described herein.

Methods employed in the Examples

Mice

C57BL/6 mice were purchased from Charles River. CXCL12/GFP knock-in mice (Ara et al., 2003) were kindly provided by Dr. Takashi Nagasawa. Blimpgfp mice (Kallies et al., 2004) were generously supplied by Dr. Stephen L. Nutt. All mice were housed under specific pathogen-free conditions and were used at 6-16 weeks of age. All mouse experiments were performed in accordance with the German law for animal protection and with permission from the local veterinary offices, and in compliance with the guidelines of the Institutional Animal Care and Use Committee.

Bacterial strains and growth condition

All Salmonella strains used in this study were derivatives of Salmonella enterica serovar

Typhimurium χ3306. Bacteria were grown in LB broth (1 % Bacto tryptone (Difco), 0.5% Bacto yeast extract (Difco), 1 % sodium chloride, pH7.4) and LB agar. When necessary, the medium was supplemented with chloramphenicol (20 μg ml), kanamycin (25 μg ml) and/or nalidixic acid (25 μg ml). The bacterial strains used in this study are detailed in Table A. The number of viable bacteria in the organs of infected mice was determined by plating serial 10-fold dilutions of the homogenates on LB agar plates. Colonies were routinely counted 18 to 24 h later.

Table A. Bacterial strains used in this study

Strains Relevant properties ³ References

E. coli

BB2395 in MC4100 Tomoyasu et al., 2001

MC4100 F- araD139 A(argF-/ac)U169 rpsL150 relM Our collection

flbB5301 deoC1 ptsF25 rbsR

Salmonella enterica serovar Typhimurium

χ3306 Virulent strain, gyrA, WT Gulig and Curtiss III, 1987

CS2022 A/on::Cm in χ3306, ALon Takaya et al., 2002

CS2609 /77θ::ΤηίΟ ίη χ3306 Tomoyasu et al., 2003 CS3186 A/on::Cm in CS2609, ALonAFIhD This study

CS10044 As/7£::Km in χ3306 This study

CS10049 As/7£::FRT in χ3306, ASiiE This study

CS10063 A/on::Cm in CS10049, ALonASiiE This study

a Cm, chloramphenicol resistance; Km, kanamycin resistance.

ELISpot assay and ELISA

To count Ig-secreting cells, Multiscreen filter plates with PVDF membrane (Merck) were activated for 1 min with 35% ethanol followed by washing and were coated with 7.2 μg ml of goat anti- mouse Ig, F(ab')2 fragment (Jackson ImmunoResearch) overnight at 4°C. After washing and blocking with RPM11640/10% FCS, diluted fresh cells were added and incubated for 5 h at 37°C. Following incubation, alkaline phosphatase-conjugated anti-IgG, lgG1 , IgM or IgA (Southern Biotech) was added for 1 h at 37°C and spots were visualized with BCIP/NBT Plus substrate (Mabtech) and were counted by ELISpot reader (AID). To measure total and a W-Salmonella antibodies, serum samples were incubated in plates coated with sonicated and filtrated

Salmonella (10 μg/ml) or goat anti-mouse Ig, F(ab')2 fragment. Isotype of antibodies was determined with alkaline phosphatase-conjugated antibodies to mouse IgG and IgM and pNPP substrate (Sigma) and was measured by SpectraMax i3x (Molecular Devices).

Flow cytometry

Single-cell suspensions were prepared from the spleen, femur, small intestine and blood of individual mice. The viability of cells was assessed by Trypan blue exclusion. Blood cells were counted by Turk's solution (Merck). The absolute number of leukocytes in blood was enumerated based on the assumption that the total blood volume is 7.5% of the body weight. The total number of BM cells was calculated assuming that the cell number yielded from one femur corresponds to 6.3% of the entire BM population. For cell staining, cells were stained for 20 min at 4 °C with antibodies against B220 (RA3-6B2), IgD (1 1.26c), CD138 (REA104), CD44 (IM7), integrin a1 (REA493), a6 (GoH3), a7 (3C12), (Miltenyi Biotec), IgM (AF6-78), integrin a2 (HMa2), aV (RMV-7) (BioLegend), a3 (goat polyclonal), BCMA (161616) (R&D systems), integrin a4 (PS2, Abeam), CXCR4 (2 B 1 1 , eBioscience), IgA (goat polyclonal anti-lgA; IgM- and IgG-absorbed, Southern Biotech) and 67-LR/RPSA (MLuC5, Santa Cruz Biotechnology). To exclude dead cells, we stained cells with 1 μg/ml propidium iodide (Sigma). For intracellular staining, cells were fixed with 2% formaldehyde (Sigma) for 15 min after cell surface staining and were stained with goat polyclonal anti-IgG Fc fragment (F(ab')2 fragment, Jackson ImmunoResearch) in the presence of 0.5% saponin (Sigma). To test the binding of SiiE fragment to IgG-secreting plasma cells, BM or splenic cells were incubated with GST-SiiE 97-170 or GST protein in Iscove's Modified

Dulbecco's Medium (IMDM) with 10% FCS and 1 mM MnCI2 on ice for 30 min, stained with antibodies against GST (B-14, Santa Cruz Biotechnology), CD138, IgM, IgA and B220 on ice for 20 min and analyzed by flow cytometry. IgM- and IgA-secreting plasma cells express surface Ig (Kamata et al., 2000; Reynolds et al., 2015). More than 95% of sorted lgM-lgA-CD138+B220- plasma cells were IgG-secreting cells when measured by ELISpot assay (data not shown).

Stained samples were measured by BD FACS Cantoll or LSRII flow cytometer (BD Biosciences) and were analyzed by FlowJo software (Flowjo, LLC). Immunofluorescent staining and confocal microscopy

For immunofluorescence staining, as described previously (Tokoyoda et al., 2009), samples were fixed in 4% paraformaldehyde and equilibrated in 30% sucrose (Sigma). Cryosections of adult femurs were produced by Kawamoto's film method (Kawamoto and Kawamoto, 2014), blocked with 5% FCS in PBS for 30 min, stained with antibodies against laminin β1 (LT3, 1 :100, Dianova), VCAM-1 (429, 1 :10, Miltenyi Biotec), fibronectin (rabbit polyclonal, 1 :700, Sigma), IgG Fc fragment (F(ab')2 fragment, 1 :400, Jackson ImmunoResearch) and IgM (11/41 , 1 :100,

eBioscience) for over 2 h and mounted with fluorescent mounting medium (DakoCytomation). Affinity-purified rabbit polyclonal anti-SiiE antibodies were generated by GenScript. As secondary antibodies, Cy3-labelled anti-rat IgG (1 :600, Jackson ImmunoResearch), AlexaFluor 546-labeled streptavidin or anti-rabbit IgG (1 :2000 or 1 :600, Life Technologies) were used. All histological analyses were carried out with a confocal laser microscope (LSM710, Carl Zeiss).

RNA preparation and quantitative RT-PCR analysis

Total RNA was isolated using the Trizol reagent (Life Technologies). The complementary DNA was synthesized using oligo (dT) primers and High Capacity RNA-to-cDNA Kit

(AppliedBiosystems). For quantitative RT-PCR analyses, the following primers were used: cxcl12 fwd AAACCAGTCAGCCTGAGCTACC (SEQ ID NO 14), rev GGCTCTGGCGATGTGGC (SEQ ID NO 15); april fwd CTGGAGGCCCAGGGAGACAT (SEQ ID NO 16), rev

GCACGGTCAGGATCAGAAGG (SEQ ID NO 17); Igalsl fwd ATCCTCGCTTCAATGCCCATGG (SEQ ID NO 18), rev GGTGATGCACACCTCTGTGATG (SEQ ID NO 19); hprt fwd

TCCTCCTCAGACCGCTTTT (SEQ ID NO 20), rev CATAACCTGGTTCATCATCGC (SEQ ID NO 21 ).

Construction of Salmonella mutant strains

The strain CS10044 (AsiiE::Km) was constructed as followed by ARed and flippase (FLP)- mediated recombination essentially as described by Datsenko and Wanner (Datsenko and Wanner, 2000). PCR products used to construct gene replacements were generated with template plasmid pKD4 and the primer set of siiE-P1 -F

(TTACCACGCCGCGTGGTTCAGTGATCATTGTCAATGGCGCTCGTGTAGGCTGGAGCTGC TT C) (SEQ ID NO 22) and siiE-P2-R

(GTGCTGTCCAGCACGATAGTCGGTTCTGACAGTAGGGTATCGCATATGAATATCCT CCTTA G) (SEQ ID NO 23). 1.4-kbp fragment generated was purified and then introduced into strain χ3306 carrying pKD46 encoding the ARed recombinase, by transformation. The insertion of Km- resistant gene in siiE locus was verified by PCR amplification of the chromosomal DNA with the primer set of siiE-check-F (TAATGCCAAAGGCGCAAAAG) (SEQ ID NO 24) and siiE-check-R (TACGTTGGTCAGGTGATCGC) (SEQ ID NO 25) and by DNA sequencing. To construct CS10049 (AsiiE::FRT), pCP20 encoding FLP recombinase was introduced into CS10044 by transformation. The FRT insertion in siiE was checked by PCR.

To construct CS3186 (ALonAFIhD) and CS10063 (ALonASiiE), bacteriophage P22 was propagated on CS2022, and the resultant lysates were used for infection of CS2609 and

CS10049, respectively. The transductants were selected for chloramphenicol resistance.

Purification of GST-tagged fusion SiiE 97-170 protein A plasmid, pTKY1271 , for purification of SiiE 97-170 protein fused to the C-terminus of the Glutathione S-transferase (GST) was amplified from the chromosome of χ3306 by colony direct PCR, using GST-SiiE97-BamHI-F (5'- CTGGGATCCTCTGCTCAGGTAGAAAAGAAAGG-3') (SEQ ID NO 26) and GST-SiiE170-Sall-R (5'- CTCGAGTCGACTTACAAAAAGTTCTGCAGCATTTC-3') (SEQ ID NO 27) primers. The fragment generated was cleaved with BamHI at the 5' end and Sail at the 3' end, and cloned into vector pGEX-6P-1 .

E. coli DH5aZ1 was transformed with the plasmid pTKY1271 , and the transformants were grown at 37°C to an OD600 of 0.5 in 3I of L broth containing 0.5% glucose and 50 μg ml ampicillin before adding IPTG to 1 mM induced GST-tagged fusion SiiE 97-170 expression. After 3 h incubation at 37°C, cells were pelleted and resuspended in B-PERTM (PBS) Bacterial Protein Extraction Reagent (ThermoFisher) containing 50 μg ml DNasel (Sigma-Aldrich). Cells were lysed for 30 min on ice and centrifuged at 8,000 xg for 30 min at 4°C. The supernatant was added to a MagneGST Glutathione Particles (Promega) equilibrated with PBS and incubated with gentle mixing for 2 h at 4°C. After washing with PBS, the fusion protein was eluted with Elution buffer (50 mM Tris-HCI pH 8.1 , 50 mM gultathione). To purified the GST-tagged fusion SiiE 97-170 protein, this fraction was run on gel chromatography (Superose6 10/300; GE Healthcare) with PBS. The peak fraction was concentrated with Centriprep YM-10 (Millipore) and then used as the purified GST-tagged fusion SiiE 97-170 protein.

Characterization of protein in culture supernatant

CS3186 cells were grown in 6 liters of LB broth at 37°C to an OD600 of 1.0 and removed by centrifugation at 6,000 xg for 10 min at 4°C. The supernatant was filtered using an Express PLUS filter system (Millipore) and then proteins were precipitated by adding ammonium sulfate to a final concentration of 80%. The precipitated proteins were collected by centrifugation at 6,000 xg for 10 min at 4°C and dissolved with 10 ml of 50 mM Tris-HCI pH8.0. After desalting by PD-10 column (GE Healthcare), proteins were loaded onto RESOURSE Q column (1 ml, GE

Healthcare), equilibrated in buffer A (20 mM Tris-HCI pH8.0, 10% glycerol) and eluted with buffer A containing a 0-1 M NaCI linear gradient. After dialysis with PBS, the ability to numerically diminish the plasma cells was assessed by inoculation of 200 μΙ of each fraction into C57BL/6 mice. Proteins in the fractions with this activity were recovered by TCA precipitation and were separated with 7.5% SDS-PAGE. The proteins visualized by Coomassie brilliant blue staining were analyzed by nano LC-MS/MS (Japan Bio Services Co.).

In vitro cell adhesion assay

As described previously (Hanazawa et al., 2013), 96-well plates (Greiner Bio-One) were immobilized with 30 μg/ml of murine laminin (Sigma) overnight at 4°C, dried, washed with PBS and blocked with 2% fatty acid-free bovine serum albumin for 2 h at 37°C. Ten thousand sorted CD138+B220-lgM-lgA- cells from BM of C57BL/6 mice were incubated with GST-SiiE 97-170 or GST protein in IMDM with 10% FCS and 1 mM MnCI2 on ice for 30 min and then incubated additionally with 1 ng/ml of phorbol 12-myristate 13-acetate for 1 h at 37°C. Following washing three times with pre-warm PBS including 1 mM CaCI2 and 0.5 mM MgCI2 with automatic microplate washer (Dispense speed 4, Aspirate speed 4, Bio-Tek), adherent cells were measured as viable cells using the Cell-titer Glo reagent (Promega) and a luminometer (SpectraMax, Molecular Devices). Statistical analyses

All statistical analyses were performed using two-tailed Student's t-tests.

Growth curve of Salmonella enterica serovar Tvohimurium

Bacterial cells of strains CS2022 (ΔΙ_οη, circle) and CS10063 (ALonASiiE, square) were grown overnight at 37°C and diluted 1 : 100 into fresh medium. At indicated time points, an aliquot of the culture was diluted with PBS and plated out on LB agar to determine the number of bacteria.

TCA precipitation of secreted proteins

Bacterial cells were grown in 10 ml of LB broth at 37°C to an OD600 of 1.0 and removed by centrifugation at 6,000 xg for 10 min at 4°C. The supernatant was filtrated using a Minisart High Flow syringe filter (Sartrius), then mixed with pre-chilled trichloroacetic acid (TCA; final concentration 10%), chilled on ice for 20 min, and centrifuged at 6,000 xg for 10 min at 4°C. The pellets were washed once with acetone and suspended in 100 μΙ of Laemmli's SDS-sample buffer. Proteins were detected by SDS-12.5% PAGE, followed by staining with Coomassie brilliant blue.

Results of the Examples

Summary of the results

Serum IgG, which is mainly generated from IgG-secreting plasma cells in the bone marrow (BM), protects our body against various pathogens. Here we show that Salmonella specifically reduces numbers of IgG-secreting plasma cells but not IgM-secreting cells in the BM and consequently reduces IgG titers in serum, whilst Salmonella is undetectable in the BM. Using chromatography and mass spectrometry, we identified SiiE protein which is secreted from Salmonella and specifically reduces numbers of IgG-secreting plasma cells in the BM. The reduction was caused by a Salmonella protein SiiE but not by lipopolysaccharide (LPS), flagellin or reduced CXCL12. SiiE-deficient Salmonella failed to reduce numbers of BM IgG-secreting plasma cells and strongly induced production of Sa/mone//a-specific IgG in the infected mice. A forty amino acid-long peptide from the N-terminal domain of SiiE protein with homology to murine laminin β1 also reduced numbers of IgG-secreting plasma cells in the BM, suggesting that SiiE inhibits the interaction between the plasma cells and laminin β1. Histological analysis revealed that laminin β1 specifically binds to IgG- but not IgM-secreting plasma cells. Our study demonstrates that laminin β1 is a component of distinct survival niches for IgG-secreting plasma cells in the BM. We suggest that Salmonella secretes SiiE and inhibits the retention of IgG-secreting plasma cells in the BM as a strategy to escape from humoral immunity. In applied terms, SiiE-deficient

Salmonella is promising vaccine candidates and SiiE-derived components would be harnessed for the treatment of autoimmune diseases and multiple myeloma by depleting pathogenic memory plasma cells in the BM.

Example 1: Salmonella specifically reduces numbers of IgG-secreting plasma cells in the BM

Salmonella escapes from humoral immunity and can survive in the body for long time periods, resulting in chronic infectious disease. Long-lasting persistence requires that Salmonella continues to relocate between short-lived macrophages via body fluids containing antibodies. We first examined the influence of Salmonella on the production of antibodies, using a chronic infection model, mimicked by intraperitoneal infection of attenuated Salmonella (Lon- depletion)(Takaya at el., 2002; Kodama et al., 2005). C57BL/6 mice received 104 colony-forming units (CFU) of the attenuated Salmonella intraperitoneal^. Infected Salmonella expanded on days 4-7 in the spleen and liver and stayed there as a small population until day 20, the end of the observation period (Figure 1). On day 4, at the peak of Salmonella expansion, polyclonal antibody-secreting cells in the spleen and BM were enumerated by ELISpot assay. Surprisingly, numbers of IgG-secreting plasma cells in the BM were reduced, but numbers of BM IgM- and splenic IgG-secreting cells were not affected (Figure 2A). Numbers of splenic IgM-secreting plasma cells were slightly increased, probably due to a generic bacterial stimulant, e.g. LPS. Moreover, numbers of Blimp-1 +CD138+lgM- lgA-B220- cells, mostly including lgG+ plasma cells, and of intracellular lgG+CD138+B220- cells in the BM were also significantly reduced (Figures 2B and 2C). The reduction of numbers of BM IgG-secreting cells was also observed after infection with wild-type Salmonella (Figure 3). The numerical reduction of BM IgG-secreting plasma cells which are the main source of serum IgG, may affect the titers of IgG in serum. On day 7 after infection, polyclonal IgG but not IgM titers in serum were significantly impaired (Figure 2D). The specific numerical reduction of BM IgG-secreting plasma cells was also shown in case of natural infection with Salmonella. Oral infection with 107 CFU of attenuated Salmonella reduced numbers of BM IgG-secreting plasma cells, but did not affect plasma cell numbers in the spleen and lamina propria (Figure 4).

Example 2: Salmonella protein SHE reduces BM IgG-secreting plasma cells

On day 4 after infection, most Salmonella could be detected in the spleen and liver but not in the BM (Figure 5A), suggesting that Salmonella in the spleen and liver impacts on IgG-secreting plasma cells in the BM from a distance, likely by secreted proteins. The culture supernatant of Salmonella includes several inducers of innate immune activation, like LPS and flagellin. We removed LPS from supernatant of flagellin-deficient attenuated Salmonella and injected the supernatant into C57BL/6 mice. Untreated and LPS-free supernatant from flagellin-deficient Salmonella reduced numbers of BM IgG-secreting plasma cells alike (Figure 5B). To determine whether the reduction is specific to Salmonella, supernatant from flagellin- and Lon-deficient Escherichia coli was injected. Escherichia coli unaffected numbers of BM IgG-secreting plasma cells (Figure 5B). The LPS/flagellin-free supernatant also reduced numbers of antigen-specific IgG-secreting plasma cells in the BM, which had been generated by immunization with (4- hydroxy-3-nitrophenyl)acetyl chicken gamma globulin (NP-CGG), as well as polyclonal IgG- secreting plasma cells (Figure 5C). These data suggest that Salmonella supernatant devoid of LPS and flagellin contains a component which impacts on BM IgG-secreting plasma cells.

We fractionated proteins in the supernatant by ion-exchange chromatography and screened each fraction for its impact on BM IgG-secreting plasma cells in vivo. By sodium dodecyl sulfate- polyacrylamide gel electrophoresis (SDS-PAGE) and mass spectrometry, we then identified a protein, SiiE, as most likely active component. Supernatant from SiiE-deficient, attenuated Salmonella failed to reduce numbers of IgG-secreting plasma cells in the BM (Figure 5D). SiiE is a large protein of 5,559 amino acids, with 2 distinct regions in the N- and C-terminus and 53 repeated bacterial Ig domains in between (Figure 6; Barlag and Hensel, 2015). SiiE is secreted and is involved in the adhesion to gut intestinal epithelial cells (Gerlach et al., 2007). We detected SiiE protein which is secreted by Salmonella and which is located on Salmonella in the spleen (Figure 74). From a search with the Basic Local Alignment Search Tool (BLAST, the National Library of Medicine), two sequences of the N-terminal region had high homologies (score <0.01) to murine laminin β1 and myosin 7A, respectively. Since myosin is an intracellular protein, we focused on laminin β1 , hypothezising that SiiE competes with laminin β1 for interaction with IgG- secreting plasma cells. SiiE 129-168, a synthetic 40-amino acid peptide with high homology to a conserved sequence of laminin β1 in many species (Figure 6), also markedly reduced numbers of BM IgG-secreting plasma cells (Figure 5E). Furthermore, SiiE 97-170 fragment could bind IgG- secreting plasma cells in the BM but not in the spleen (Figure 5F) and could inhibit the adhesion of BM IgG-secreting plasma cells to laminin in vitro (Figure 5G). These results suggest that SiiE, a microbial component from Salmonella, modulates BM IgG-secreting plasma cells by competing with laminin β1.

Example 3: Laminin B1+CXCL12+ stromal cells organize survival niches forBM IgG-secreting plasma cells

Does laminin β1 bind to BM IgG-secreting plasma cells? Histological analysis showed that laminin β1 is ubiquitously distributed in the marrow (Figure 8A, left). About 30 % of CXCL12+ stromal cells were costained for laminin β1 . Laminin β1 is distributed on the cell surface and cellular processes of CXCL12+ stromal cells (Figure 8A, right). To determine whether laminin β1 interacts with lgG+ or lgM+ Blimp-1 + plasma cells in the BM and spleen, we stained frozen sections of Blimpgfp mice for laminin β1 and IgG or IgM. About 90 % of BM lgG+Blimp-1 + plasma cells bound to laminin β1 , while fewer lgM+Blimp-1 + and splenic lgG+Blimp-1 + plasma cells attached to laminin β1 (Figures 8B and 9). We had already shown earlier that about 90% of the lgG+ plasma cells are in contact with CXCL12-expressing cells (Tokoyoda et al., 2004;

Zehentmeier et al., 2014). In fact, most lgG+ cells contacted laminin βΐ -coated CXCL12+ cells (Figure 8C). These histological data suggest that BM IgG-secreting plasma cells preferentially reside in laminin β1 +ΟΧΟΙ_12+ stromal niches. How do IgG-secreting plasma cells bind to laminin β1 ? The potential receptors for laminin are integrin a1 , a2, a3, a6, a7 and aV and 67kD laminin receptor (RPSA) (Gu et al., 1999; Belkin and Stepp, 2000). We compared the expression of these receptors on IgM- and lgM+ Blimp-1 + plasma cells in the BM and spleen (Figure 10). Most receptors were expressed or not on both IgM- and lgM+ plasma cells, although more BM IgM- Blimp-1 + plasma cells expressed integrin a2 than other plasma cells.

Example 4: Loss of SiiE enhances the production of anti-Salmonella IgG

As shown above, SiiE inhibits the residency of BM IgG-secreting plasma cells, since culture supernatant of SiiE-deficient mutant fails to reduce plasma cell numbers. We thus expected that the SiiE mutant, because it does not impact on BM IgG-secreting plasma cells via SiiE, enhances production of antibodies against Salmonella. C57BL/6 mice infected with the SiiE mutant bacteria were analyzed for their titers of anti- Salmonella IgG. The SiiE-competent and the SiiE mutant strains of Salmonella did expand normally in vitro (Figure 1 1A) and in vivo (Figure 12A) and both secreted proteins and LPS into their supernatants (Figure 1 1 B; data not shown). The SiiE- deficient strain, however, induced significantly more a W-Salmonella IgG as compared to the SiiE- competent strain (Figure 12B). To evaluate the mutant strain as a protective vaccine, mice primed by SiiE-competent or -deficient Salmonella were challenged with a lethal dose of wild-type Salmonella. On day 7 after challenge, all naive mice had died, while both groups of the vaccinated mice survived. Mice vaccinated with SiiE-deficient Salmonella strongly suppressed the expansion of virulent Salmonella in the spleen, as compared to mice vaccinated with SiiE- competent Salmonella (Figure 12C). These data characterize SiiE-deficient Salmonella as a potential vaccine. Example 5: CXCL12-dependent reduction of B cells but not IgG-secreting plasma cells by Salmonella

Bacterial infection affects the innate and the adaptive immune system. Salmonella reduced numbers of B cells in the BM and increased numbers of B cells in the spleen on day 4 after infection (Figures 13A and 13B). In the blood, although the total B cell numbers were unaffected, CD43+lgM-lgD- B cells were significantly increased numerically (Figure 13C; data not shown). Since numbers of CD43+lgM-lgD- B cell precursors in the BM were dramatically decreased (Figure 13A), the blood CD43+lgM-lgD- B cells had most likely egressed from the BM. Numbers of IgG-secreting plasma cells were not increased in the spleen (Figure 2A) and blood (data not shown) after infection with Salmonella. Since BM B cell precursors are retained by CXCL12 and VCAM-1/fibronectin (Miyake et al., 1991 ; Nagasawa et al., 1996; Kawano et al., 2017), we examined the expression of CXCL12 and VCAM-1/fibronectin and their receptors. While the expression of VCAM-1/fibronectin on stromal cells and integrin a4, a receptor of VCAM- 1/fibronectin, on lgG+ plasma cells was unaffected (Figures S8A and S8B), the expression of CXCL12 was greatly impaired as shown by histological analysis (Figure 6D), quantitative RT- PCR (Figure 13E) and flow cytometry (Figure 13F). The expression of CXCR4, a receptor of CXCL12, on BM lgG+ plasma cells was not altered by infection with Salmonella (Figure 13G). To determine whether loss of CXCL12 by Salmonella affects the reduction of IgG-secreting plasma cell numbers in the BM, we examined the effect of CXCL12/CXCR4 antagonists in the persistence of BM IgG-secreting plasma cells. On day 4 after the first injection of the antagonist, numbers of IgG-secreting plasma cells in the BM were not affected, while B cell numbers in the BM were reduced (Figures 13H and 131). Salmonella did not affect other molecules involved in the adhesion and survival of BM plasma cells; CD44, BCMA, APRIL and Galectin-1 (Figures 14C- 14F). We conclude that reduced numbers of IgG-secreting plasma cells were caused by SiiE from Salmonella but not by the downregulation of CXCL12.

Example 15: SHE129 peptide reduce numbers of DNA-specific IgG-secreting plasma cells in the bone marrow in a murine model of systemic lupus erythematosus.

NZB W F1 female mice (5-6 months old) received i.p. 100 μg peptide coding SiiE amino acid 129- 168 on days 0, 3, 7 and 10 and on day 1 1 were analyzed for anti-DNA IgG-secreting cells in the BM by ELISpot assay. The data show that SiiE 129-168 reduces the number of Anti-DNA IgG- secreting cells in bone marrow (Figure 15).

Discussion

We here show that Salmonella specifically reduces numbers of IgG-secreting plasma cells in the BM, which are a main source of serum IgG, in an SiiE-dependent and CXCL12-independent manner. Since no Salmonella could be detected in the BM and the reduction was also induced by culture supernatant of Salmonella, we conclude that a secreted component of Salmonella is responsible. We have identified the Salmonella protein SiiE as the responsible component. A peptide of SiiE, which has high homology to murine laminin β1 , was able to reduce numbers of BM IgG-secreting plasma cells. Histological analyses of the BM revealed that IgG- but not IgM- secreting plasma cells bind to laminin β1 . Thus, laminin i +CXCL12+ stromal cells are an integral part of the survival niches for IgG-secreting plasma cells in the BM, a lesson learnt from Salmonella. We had shown earlier that BM lgG+ plasma cells reside in CXCL12+ stromal niches (Tokoyoda et al., 2004). Although the character of IgM-secreting plasma cells remains controversial, they reside in the BM and are the main source of natural IgM in serum (Reynolds et al., 2015).

Reynolds et al. suggested that IgM- and IgG-secreting plasma cells localize in distinct niches, because fewer lgM+ plasma cells are in contact with eosinophils in comparison to lgG+ plasma cells. Here we identify one essential difference between survival niches for IgM- and IgG- secreting plasma cells: the presence of laminin β1. The receptor of BM IgG-secreting plasma cells, as well as the intracellular signaling events, remain enigmatic, although more BM IgM- Blimp-1 + plasma cells, which include IgG-secreting plasma cells, express integrin a2 than BM lgM+Blimp-1 + and splenic Blimp-1 + plasma cells.

We posed the question as to how the plasma cells disappeared, e.g. by egress or death. No egress of IgG-secreting plasma cells into the spleen and blood could be detected on day 4 after intraperitoneal infection. Slocombe et al. showed that on days 8 and 16 after intravenous infection with 106 CFU of attenuated Salmonella, BM lg+ plasma cells migrated into the spleen and then failed to return to the BM, perhaps because of the reduced expression of CXCL12 in the BM

(Slocombe et al., 2013). The longterm reduction until day 16 suggests that the plasma cells were detached from their survival niches by the Sa/mone//a-specific protein SiiE and died by lack of survival factors.

Salmonella affects the expression of CXCL12 but not fibronectin, VCAM-1 and APRIL. CXCL12 is required for the formation of long-lived memory plasma cells in the BM, because CXCR4-deficient fetal liver cells fail to generate the plasma cells (Hargreaves et al., 2001 ). However, it was controversial when CXCL12 is required during the formation; i.e. migration and/or maintenance. Hauser et al. showed that the migratory capacity of newly generated plasma cells is lost between day 8 and 12 after boost, suggesting that CXCL12 is required for the migration of plasma cells into their survival niches but not for their maintenance (Hauser et al., 2002). We here show that CXCR4 antagonist can inhibit the retention of B cells but not IgG-secreting plasma cells. Our data directly support the hypothesis that CXCL12 is not required for the retention and maintenance of IgG-secreting plasma cells in the BM.

Our data suggest that SiiE inhibits the interaction of IgG-secreting plasma cells with laminin β1 in the BM. Salmonella thus modulates humoral immunity by reducing numbers of IgG-secreting plasma cells in the BM. Laminin β1 is also expressed on mucosal epithelia. In mice and cattle, the loss of SiiE attenuated the virulence of natural oral infection with Salmonella, but not of intraperitoneal infection with Salmonella (Morgan et al., 2004; Kiss et al., 2007). Orally-infected Salmonella secretes SiiE and invades into the gut, likely blocking the interaction of laminin β1 and its receptors on epithelia. The ability to persist in the gut may be utilized as a side effect to replace BM IgG-secreting plasma cells. The gain of SiiE in Salmonella may provide advantage for the residence in animal and human hosts.

Salmonella specifically reduced all kinds of IgG-secreting plasma cells in the BM on day 4 after infection. In mice previously infected with Salmonella, newly invaded Salmonella can reduce long- lived anti- Salmonella IgG-secreting plasma cells which the main source of a W-Salmonella IgG in circulation. The depletion of humoral immune memory enables the new Salmonella to spread in the host. Infection with Salmonella induces humoral immune reaction (Figure 5B; MacLennan, 2014; Di Niro et al., 2015). However, it remained unknown whether Salmonella affects humoral immune memory. We here show that Salmonella induces immune reaction and impairs immune memory in an SiiE-dependent manner. These data suggest that Salmonella escapes from humoral immunity, depleting memory plasma cells and also inhibiting the generation of memory plasma cells.

Infection with Salmonella enterica serovar Typhi, which is restricted to humans and causes severe and often fatal typhoid fever, can be prevented by vaccination with attenuated strains, e.g. Ty21 a (Anwar et al., 2014). In contrast, vaccination against Salmonella enterica serovar

Typhimurium, which causes severe food poisoning in humans, cattle, swine, sheep, horses, rodents and galliformes is not yet available. Diseases caused by these invasive nontyphoidal Salmonella (iNTS), including Salmonella enterica serovar Typhimurium, have been neglected, although the fatality rate at 20-25% is higher than that by infection with Salmonella enterica serovar Typhi (MacLennan et al., 2014). The SiiE gene in Salmonella enterica serovar Typhi has been reported as two distinct ORFs (9,852 bp and 6,771 bp, Typhimurium has 16,680 bp), suggesting that it is a pseudogene (Main-Hester et al., 2008). Furthermore, siiE gene in

Salmonella enterica serovar Typhi has a mutation (148 A>T) within the sequence with closed homology to laminin β1. A lack of SiiE or non-functional SiiE in Salmonella enterica serovar Typhi may be a reason why potent vaccines against Salmonella Typhi are available. We show here that SiiE-deficient mutant of Salmonella enterica serovar Typhimurium can induce efficient immune responses, as compared to SiiE-competent Salmonella. To establish vaccines against iNTS, including Salmonella enterica serovar Typhimurium, we propose SiiE-deficient mutant attenuated Salmonella as a novel vaccine.

SiiE peptide homologous to laminin β1 significantly reduced numbers of IgG-secreting plasma cells in the BM. This property could be exploited for the treatment of autoimmune diseases and multiple myeloma. Autoimmune diseases with a substantial contribution of pathogenic IgG autoantibodies, like systemic lupus erythematosous, can be refractory to conventional treatment, because BM plasma cells secreting these autoantibodies are protected in their BM niches (Hoyer et al., 2004; Hiepe et al., 201 1 ; Cheng et al., 2013). The SiiE-derived laminin β1 homologue is a candidate for depletion of refractory autoantibody-secreting BM plasma cells. Multiple myeloma is caused by redundant titers of antibodies generated from plasma cell myeloma in the BM. It has been already reported that myeloma cell lines preferentially contact laminin in vitro (Kibler et al., 1998; Vande Broek et al., 2001 ), suggesting that targeting of adhesion molecules including laminin should be considered as novel therapy (Neri and Bahlis, 2012). The depletion of BM plasma cell myeloma may directly ameliorate disease.

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