FIELD OF THE INVENTION

The present invention relates to peptides, their use in the treatment, amelioration or prevention of chronically active autoimmune inflammation, in particular rheumatoid arthritis, and to pharmaceutical compositions comprising the same.

BACKGROUND OF THE INVENTION

Rheumatoid Arthritis (RA) is one of the most common systemic autoimmune diseases with a prevalence of 0.5-1% in the overall population [1] Several risk factors contribute to the development of RA, including genetic factors, age and gender, smoking, socioeconomic status and infections [2] Pathophysiology includes inflammatory arthritis, but also extraarticular manifestations of disease with cardiovascular, pulmonary, psychological and skeletal disorders [3] Rheumatoid factor (RF), anti-citrullinated peptide antibodies (ACPAs) [4] and anti-collagen-ll antibodies [5] are commonly found in sera of patients with RA.

Therapy of rheumatoid arthritis mainly relies on disease modifying anti-rheumatic drugs (DMARDs) such as the conventional synthetic methotrexate, biological drugs (TNF-, T cell, B cell or IL-6R-inhibitors) or the targeted synthetic janus kinase inhibitor tofacitinib. Although there are many therapeutic approaches, remission or low disease activity is not achieved in all patients, or the patients lose responsiveness over time [6] In addition, some of those therapeutics result in nonspecific immunosuppression, which can lead to complications such as infections or cancer [7-9] Thus, further study of RA and search for therapies is needed. Peptides can regulate the immune response to induce tolerance of certain antigens and are a promising approach in mitigating or even curing autoimmune diseases and other immunological disorders [10, 11] The immunodominant T cell epitope of bovine collagen II (bCII) has been shown to be a peptide with only eight amino acids at positions 260-267 of the collagen a-chain [12, 13] Several studies which investigated the effects of this peptide on the outcome of collagen-induced arthritis (CIA) in mice have been conducted and evaluated. Coimmunization with CM and of Cll-derived peptide 245-270 [s260,261 ,263] leads to a dose-dependent effect on the incidence of arthritis in the mouse CIA model in DBA/1 mice. When the peptide was mixed together with collagen at a dose which exceeded the amount of collagen II molecules by 480-fold on a molar basis, this mixture succeeded in completely preventing the development of arthritis in CIA mice [14] Intravenous or intranasal administration of a galactosylated CM 259-273 in complex with MHC-ll-molecules A ^q reduced the incidence and severity of CIA in B10.Q mice and ameliorated chronic relapsing disease [15] Gene therapy with hematopoietic stem cells which had been infected with lentiviral particles expressing the CM 259-270 peptide on MHC-A ^q - complex several weeks before the immunization reduced the rate and the severity of CIA in DBA/1 mice [16] In a rat model of adjuvant-induced arthritis (AIA), s.c. injections of a multi-epitope peptide reduced disease severity [17]

With the exception of the multi-epitope peptide tested in AIA rats [17], these peptide administrations relied on cofactors or recombinant viral gene transfer [15, 16] or were only effective if given before or simultaneously with the immunization [14, 16]

SUMMARY OF THE INVENTION

In view of the above, it is the problem of the present invention to provide a further peptide which is suitable for the treatment, amelioration or prevention of chronically active autoimmune inflammation, in particular rheumatoid arthritis, which does not show the above disadvantageous, in particular are effective on their own and are effective even when administered after the onset of the disease or the development of disease symptoms.

It has been surprisingly found that specific fructosylated peptides which were derived from the immunodominant T cell epitope of bovine collagen II (bC II) also induced tolerance and successfully treated rheumatoid arthritis.

The present invention provides peptides comprising the amino acid sequence of SEQ ID NO: 1 (GEPGIAGFKGEQGPK), or a derivative thereof, wherein one or two amino acids, except the lysine corresponding to position 9 of SEQ ID NO: 1 , have been replaced by another amino acid or have been removed, and wherein the lysine corresponding to position 9 of SEQ ID NO: 1 is glycosylated with a D- fructosyl residue. Theses peptides may be used in the treatment, amelioration or prevention of chronically active autoimmune inflammation, in particular rheumatoid arthritis.

Further, the present invention provides a pharmaceutical composition comprising said peptides, and optionally a pharmaceutically acceptable carrier. The peptide and the pharmaceutical composition are used for the treatment, amelioration or prevention of chronically active autoimmune inflammation, in particular rheumatoid arthritis.

BRIEF DESCRIPTION OF THE DRAWINGS

In the application and in the Figures, the preferred peptide in accordance with the present invention is sometimes indicated as “peptide 90578". The non-fructosylated derivative of “peptide 90578" is referred to as “peptide 90091".

Figure 1 shows the chemical structure of peptide 90578 (SEQ ID NO: 1).

Figure 2 shows clinical and histological results of the pilot study for FIA-CIA.

Figure 3 shows the results of ELISA studies of the sera in FIA-CIA.

Figure 4 shows the results of histological findings in the therapy study with peptides 90091 and 90578 or NaCI.

Figure 5 shows the clinical results of the therapy study with peptides 90091 and 90578 or NaCI.

Figure 6 shows the Kaplan-Meier-Chart of the survival probability in different treatment groups. DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention provides a peptide comprising the amino acid sequence of SEQ ID NO: 1 (GEPGIAGFKGEQGPK), or a derivative thereof, wherein one or two amino acids, except the lysine corresponding to position 9 of SEQ ID NO: 1 , have been replaced by another amino acid or have been removed.

Without wishing to be bound by any theory in the following, the present inventors have surprisingly found that specific fructosylated peptides which were derived from the immunodominant T cell epitope of bovine collagen II (bCII) induced tolerance and successfully treated rheumatoid arthritis. In particular, arthritis development was investigated in male DBA/1 mice which were injected with bovine collagen II (bCII) and human fibrinogen (hFib) on days 0 and 21 , leading to stable and reproducible disease induction in 100% of immunized mice (FIA-CIA). In a second study, two bCII - derived peptides were given three times in the course of six weeks after FIA- CIA induction to test for impact on arthritis. Mice were scored weekly for arthritis and anti-citrullinated peptide antibodies (ACPAs) were determined in the sera taken on days 0, 14, 35, 56 and 84. Histology of the hind paws was performed at the end of the experiment. The Results showed that intravenous administration of peptide 90578, a novel fructosylated peptide derived from the immunodominant T cell epitope of bCII, at a dosage of 1 mg/kg resulted in significant beneficial effects on clinical outcome parameters and on the arthritis histology scores which was sustained over twelve weeks. Survival tended to be improved in peptide 90578- treated mice. In conclusion it could be shown that intravenous administration of pure soluble peptide 90578 without adjuvants is a promising approach to treat RA, with treatment starting at a time when ACPAs are already present. The results complement existing data on peptide “vaccination” of healthy animals, or on treatment using recombinant peptide expressing virus or complex biological compounds.

In summary, the present results show that treatment of clinical disease manifestations in a mouse model of rheumatoid arthritis by specific fructosylated peptides which were derived from the immunodominant T cell epitope of bovine collagen II (bCII) led to marked improvement of several disease parameters. The present invention provides a peptide comprising the amino acid sequence of SEQ ID NO: 1 (GEPGIAGFKGEQGPK), or a derivative thereof, wherein one or two amino acids, except the lysine corresponding to position 9 of SEQ ID NO: 1 , have been replaced by another amino acid or have been removed. Preferably, the peptide comprises at least 15 amino acids, most preferably the amino acids of SEQ ID NO: 1. Preferably, the peptide comprises at most 45 amino acids, more preferably at most 30 amino acids. Typically, the peptide comprises about 15 to 20 amino acids in total.

The lysine corresponding to position 9 of SEQ ID NO: 1 is glycosylated with a D- fructosyl residue. As shown in Figure 1, the lysine residue at its its e-amino group is glycosylated with a D-fructose residue, also termed herein D-fructosyl residue, in the form of D-fructopyranose. In an alternative embodiment, the lysine residue is glycosylated with a D-fructose residue in the form of D-fructofuranose. Glycosylation and suitable reactions to obtain peptides having a lysine glycosylated with a D- fructosyl residue are known in the art.

In accordance therewith, the invention relates to the general peptide structure as reflected by the above description. It will also be understood by the ones skilled in the art that the individual amino acid may be replaced by another naturally occurring or synthetic amino acid, preferably if both amino acids belong to the same category of amino acids. In accordance therewith, for example, an acidic amino acid can be replaced by another acidic amino acid, a basic amino acid may be replaced by another basic amino acid and so on. It will also be acknowledged by the ones skilled in the art that one or several of the amino acids forming the peptide of the present invention may be modified. In accordance therewith any amino acid as used herein preferably also represents its modified form. For example, an alanine residue as used herein also comprises modified alanine. Such modifications may, among others, be a methylation or acylation or the like, whereby such modification or modified amino acid is preferably comprised by the present invention as long as the thus modified amino acid and more particularly the peptide containing said thus modified amino acid is still functionally active as defined herein, more particularly functionally active in accordance with the present invention. Respective assays for determining whether such a peptide, i. e. a peptide comprising one or several modified amino acids, fulfils this requirement, are known to the one skilled in the art and, among others, also described herein, particularly in the examples. In a preferred embodiment, the C-terminus of the peptide of the invention is amidated.

The invention comprises also derivatives of the peptides such as salts with physiologic organic and inorganic acids like HCI, H2SO4, H3PO4, malic acid, fumaric acid, citric acid, tartaric acid, acetic acid, and trifluoroacetic acid.

According to the practice in the art, sequences of peptides are indicated from the N- terminus to the C- terminus, whereby the N-terminus is at the left side and the C- terminus is at the right side of the respective depicted amino acid sequence.

In a preferred embodiment when an amino acid is replaced, the introduced amino acids are selected from acidic, basic, neutral and/or aliphatic amino acids.

Preferably an acidic amino acid is an amino acid selected from the group comprising Asp, Asn, Glu, and Gin; preferably a basic amino acid is an amino acid selected from the group comprising Arg and Lys; preferably a neutral amino acid is an amino acid selected from the group comprising Gly, Ala, Ser, Thr, Val, Leu, He; preferably an aliphatic amino acid is an amino acid which is selected from the group comprising Gly, Ala, Ser, Thr, Val, Leu, He, Asp, Asn, Glu, Gin, Arg, Lys, Cys and Met.

In a preferred embodiment when an amino acid is replaced, the amino acid is conservatively replaced. Conservatively replaced means as known in the art, i.e. the that amino acids are sorted into six main classes, as shown below, and the replacement is within the class: a) Aliphatic: Glycine, Alanine, Valine, Leucine, Isoleucine b) Hydroxyl or sulfur/selenium-containing: Serine, Cysteine, Selenocysteine, Threonine, Methionine c) Cyclic: Proline d) Aromatic: Phenylalanine, Tyrosine, Tryptophan e) Basic: Histidine, Lysine, Arginine f) Acidic and their amides: Aspartate, Glutamate, Asparagine, Glutamine.

As used herein, the expression that one particular amino acid, such as, e. g., a basic amino acid, is replaced by a different amino acid which is selected from a respective particular group of amino acids, such as, e. g., the group comprising basic amino acids, preferably means that the particular amino acid is replaced by another, i.e. different amino acid under the proviso that such different amino acid is part of the respective particular group of amino acids.

The peptides (also referred to herein as "active compound") of the invention can be incorporated into pharmaceutical compositions suitable for administration. Such compositions typically comprise the peptide and a pharmaceutically acceptable carrier. As used herein the language "pharmaceutically acceptable carrier" includes solvents, dispersion media, coatings, antibacterial and antifungal agents, isotonic and absorption delaying agents, which are compatible with pharmaceutical administration. Additional active compounds may be incorporated into the compositions.

A pharmaceutical composition of the invention is formulated to be compatible with its intended route of administration. Preferable routes of administration include parenteral, e.g., intravenous or intraarterial administration. Solutions or suspensions used for parenteral: a sterile diluent such as water for injection, saline solution, fixed oils, polyethylene glycols, glycerine, propylene glycol or other synthetic solvents; antibacterial agents such as benzyl alcohol or methyl parabens; antioxidants such as ascorbic acid or sodium bisulfite; chelating agents such as ethylenediaminetetraacetic acid; buffers such as acetates, citrates or phosphates and agents for the adjustment of tonicity such as sodium chloride or dextrose. The pH can be adjusted with acids or bases, such as hydrochloric acid or sodium hydroxide. The parenteral preparation can be enclosed in ampoules, disposable syringes or multiple dose vials made of glass or plastic. Pharmaceutical compositions suitable for injectable use include sterile aqueous solutions or dispersions and sterile powders for the extemporaneous preparation of sterile injectable solutions or dispersion. For intravenous administration, suitable carriers include physiological saline, Cremophor EL (BASF; Parsippany, N.J.) or phosphate buffered saline (PBS). In all cases, the composition must be sterile and should be fluid to the extent that easy syringability exists. It must be stable under the conditions of manufacture and storage and must be preserved against the contaminating action of microorganisms such as bacteria and fungi.

The carrier can be a solvent or dispersion medium containing, for example, water, ethanol, polyol (for example, glycerol, propylene glycol, and liquid polyetheylene glycol), and mixtures thereof. The proper fluidity can be maintained, for example, by the use of a coating such as lecithin, by the maintenance of the required particle size in the case of dispersion and by the use of surfactants. Prevention of the action of microorganisms can be achieved by various antibacterial and antifungal agents, for example, parabens, chlorobutanol, phenol, ascorbic acid, thimerosal, and the like. In many cases, it will be preferable to include isotonic agents, for example, sugars, polyalcohols such as mannitol, sorbitol, sodium chloride in the composition.

Sterile injectable solutions can be prepared by incorporating the active compound in the required amount in an appropriate solvent with one or a combination of ingredients enumerated above, as required, followed by filtered sterilization. Generally, dispersions are prepared by incorporating the active compound into a sterile vehicle which contains a basic dispersion medium and the required other ingredients from those enumerated above. In the case of sterile powders for the preparation of sterile injectable solutions, the preferred methods of preparation are vacuum drying and freeze-drying which yields a powder of the active ingredient plus any additional desired ingredient from a previously sterile-filtered solution thereof.

It is especially advantageous to formulate nasal or parenteral compositions in dosage unit form for ease of administration and uniformity of dosage. Dosage unit form as used herein refers to physically discrete units suited as unitary dosages for the subject to be treated. Each unit contains a predetermined quantity of active compound calculated to produce the desired therapeutic effect in association with the required pharmaceutical carrier.

The active ingredient may be present in the pharmaceutical composition in the range of 1 pg/kg to 100 mg/kg, preferably 10 pg/kg to 1000 pg/kg, e.g. about 100 pg/kg, depending on the application form, preferably s.c. or i.v. application. A suitable dosing interval is from one week to three months, e.g. every two to four weeks.

It is within the present invention that the peptide and the pharmaceutical composition is used for the treatment of any of the diseases and patient groups as defined above including the treatment, amelioration or prevention of chronically active autoimmune inflammation, in particular rheumatoid arthritis in these patients by using the aforementioned compounds. Also, the peptides according to the present invention may be used for the preparation of a medicament for the treatment and/or prevention of any of the diseases and patient groups as defined above in connection with the pharmaceutical composition.

Finally, the present invention is related to a method for the treatment of patients as defined above, whereby the patient is in need of such treatment and whereby the method comprises administering to said patient a pharmaceutically effective amount of the peptide of the present invention, or the pharmaceutical composition or the medicament disclosed herein.

Preferably, a therapeutically effective dose refers to that amount of the active ingredient that produces amelioration of symptoms of a subject which can be determined by the one skilled in the art doing routine testing. A "patient" for the purposes of the present invention, i.e. to whom a compound according to the present invention or a pharmaceutical composition according to the present invention is administered, includes both humans and other animals and organisms. Thus the compounds, pharmaceutical compositions and methods are applicable to or in connection with both human therapy and veterinary applications, in the most preferred embodiment the patient is human. LITERATURE

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The present invention will now be further illustrated by the following figures and examples.

Figure 1 shows the fructosyl structure of peptide 90578, the most preferred peptide according to the invention. The peptide structure was modified by adding a cyclic fructosyl structure to the lysine residue. To enhance legibility, this lysine residue is shown as chemical structure, whereas the other amino acids of the peptide are just indicated as single letter codes.

Figure 2 shows clinical and histological results of the pilot study for FIA-CIA. The results shown are the following: (A) Arthritis prevalence in immunized mice, (B) mean arthritis score of immunized mice, (C) mean swelling of joints of immunized (a: tarsal; b: carpal) vs native control (c: carpal; d: tarsal) mice, (D) Paws of immunized (left) and native (right) mice are shown in comparison. Swelling and ankylosis of joints, toes are thickened and the claws prolonged in immunized mice. (E) Mean histology scores of immunized and native mice. Results for 8 immunized mice and 2 native controls are shown. Histology score of FIA-CIA mice was significantly increased compared to that of native (not immunized) controls: *p<0.05, **p<0.01, ***p=0.002; error bars indicate standard errors of the mean (SEM).

Figure 3 shows the results of ELISA studies of the sera in FIA-CIA as follows: (A) Antibody titers against the immunizing antigens bCII (a), hFib (b) and citrullinated fibrinogen (c) on day 84, at the end of the experiment. Repeated measurements were carried out for all antibodies, and showed rapid increases of anti-fibrinogen, anti-collagen and anti-citrullinated fibrinogen antibodies to high values after 14 - 35 days, which did not change thereafter. For reasons of clarity we only show the values obtained at the final blood sampling upon sacrifice. Antibody titers of native control animals are shown (indicated as d), and were negative (zero values) for all 3 investigated antibodies. Repeated measurements were carried out for anti-CCP antibodies, since not enough blood volume was obtained to carry out all measurements at all time points, but only at the final blood sampling upon sacrifice.

(B) Antibodies against CCP, left columns: immunized; right columns: native control; *p<0.05, **p<0.01; error bars indicate SEM. Repeated measurements were carried out for anti-CCP antibodies, since not enough blood volume was obtained to carry out all measurements at all time points, but only at the final blood sampling upon sacrifice.

Figure 4 shows the Histological findings in the therapy study with peptides 90091 and 90578 or NaCI as follows: (A) Mean histology scores of CFA-immunized control mice and FIA-CIA mice treated with peptides 90091 (N = 8 independent animals), 90578 (N = 8) or NaCI (N =7). Error bars indicate SEM; *p<0.05 (all values compared to NaCI control mice).

(B-E) Overview of the tarsus, (F-l) ankle joint, (J-M) tarsal joint. (B,F,J) Mice immunized with CFA alone, (C,G,K) FIA-CIA immunized mice treated with NaCI, (D,H,L) FIA-CIA immunized mice treated with peptide 90091 , (E,I,M) FIA-CIA immunized mice treated with peptide 90578. Arrows indicate histological changes in the FIA-CIA group.

Figure 5 shows the clinical results of the therapy study with peptides 90091 and 90578 or NaCI as follows: (A) Mean paw swelling of tarsal joints, (B) mean arthritis score, (C) prevalence of arthritis. Treatments: a: peptide 90091 (N = 8 independent animals) b: peptide 90578 (N = 8); c: NaCI (N =7); d: CFA-immunized negative controls (N = 2); *p<0.05 (all values compared to NaCI control mice); error bars indicate SEM.

Figure 6 shows a Kaplan-Meier-Chart of the survival probability in different treatment groups. Mice were killed prior to the end of experiment when arthritis was too severe. Treatments: b: peptide 90578; a: peptide 90091 ; c: NaCI EXAMPLES

Materials and methods

Animals

Male DBA/1 mice were purchased from Janvier (Janvier Labs, France). The mice were housed under standard housing conditions in individual ventilated cages (IVC) and were fed a high-fat diet (JL Maus 5K20mod.; ssniff Spezialdiaten GmbH,

Soest). To minimize the risk of fighting, mice were housed in groups of three per cage. Enrichment material contained nestlets (NES3600-NESTLETS, Ancare, Bellmore, NY), other nesting material (Bed r ^' Nest®, The Andresons, Maumee, Ohio) and cellulose (Covetrus). After arthritis onset the litter was upped so that the mice could reach food and water standing on four paws. Mice were 8 weeks of age at the time of the first immunization. A total of 47 mice were used in the experiments. In the pilot study, 10 mice were immunized according to the protocol which is outlined below and 2 mice served as native controls without immunization. For acclimatization, mice were obtained at an age of 6 weeks and housed for 2 weeks before the start of the experiment. In the therapy study, 30 mice were immunized and randomly distributed to the three treatment groups. 5 mice were investigated in the Complete Freund ^' s Adjuvant (CFA) control group, in which no therapeutic peptide was added. Sample size calculation was done a priori based on other RA mouse model effect sizes and a power of 80%.

Personnel which handled or investigated these mice were blinded to the treatment. All animal experiments were performed in accordance to Directive 2010/63/EU and approved of by the Government of Upper Bavaria, reference number: 55.2Vet- 2532. Vet_02-17-94. The description of all procedures involving animals was done according to the ARRIVE Guidelines in reporting in vivo experiments [28]

Immunization

Bovine collagen II (bC II; Chondrex, Inc.) and human fibrinogen (hFib; Millipore/Calbiochem) were dissolved according to the manufacturers ^' instructions to a final concentration of 4mg/ml for bCII and 8mg/ml for hFib. Then each solution was emulgated separately in a 1 :1 ratio with complete Freund ^' s adjuvant (CFA; Chondrex, Inc.) containing 2mg/ml M. tuberculosis FI-37 RA. For emulgation, two luer lock glass syringes were linked via a micro-emulsifying needle (Sigma-Aldrich) and the substances were mixed until there was a stabile emulsion.

Mice were anesthesized with isoflurane (CP-Pharma) at a concentration of 1 ,5-2%. For analgesia, novaminsulfon (metamizol; bela-pharm) was given subcutaneously (s.c.). Then 50pl of bCII-CFA emulsion was administered s.c. at the base of the tail and 50mI of hFib-CFA emulsion was administered s.c. at the left flank. On day 21 after the first immunization, mice were boosted with 50mI hFib in incomplete Freund ^' s Adjuvant (IFA) s.c. at the left flank. CFA control mice were administered the equivalent doses of CFA and IFA emulgated with 0.9% NaCI to reach equal injection volumes. Native control mice did not receive any immunization. Both CFA and native control mice served as negative control in the experiments.

For treatment of pain in arthritic animals, Metacam® (meloxicam; Boehringer Ingelheim) was used at a dosage of 1 mg/kg. For treatment of severe local reactions to the first immunization, afflicted animals were treated with 10mg/kg Baytril® (enrofloxacin; Bayer) for 5 days per os.

Clinical Investigation

Paws were measured weekly. For that purpose, the mice were anesthesized shortly with isoflurane and the carpal and tarsal joints were measured via a caliper (Kafer Messuhren, Germany) [19] In addition, each paw was scored according to an arthritis scoring system (score 0= normal paw; score 1= 1 toe inflamed and swollen; score 2= >1 toe swollen or carpal/tarsal joint swollen; score 3= entire paw inflamed and swollen; score 4= very inflamed and swollen paw or ankylosis of the paw). Scores were added up to a total score of 0-16 per mouse. Upon development of arthritis, mice were examined daily. If an animal did not put weight on or use a paw anymore, it was euthanized immediately.

Synthesis of peptides Peptides represented the immunodominant T-cell determinant of bCII, peptides 256- 270 of the a-chain [12] Peptide 90091 was synthesized with the amino sequence GEPGIAGFKGEQGPK (SEQ ID No:1 ). Peptide 90578 was based on the same amino acid sequence, but posttranslationally modified by adding a fructosyl residue to the lysine at position 264, thus creating a novel chemical structure core (see Figure 1 ). Both were synthesized by Biosyntan Berlin according to described protocols of fluorenylmethoxycarbonyl (FMOC) resin-based amino acid chain elongation. Both peptides were purified up to 95% (<= 95%) by means of FIPLC and analyzed by MALDI-TOF mass spectrometry.

Serum collection and peptide treatment application

Serum was collected on days 0, 14, 35 and 56 of the experiment via bleeding of the tail vein. Treatment with peptides 90091 , 90578 (at a concentration of 1 mg/kg body weight) or 0.9% NaCI was applied intravenously on day 14, 35 and 56. Mice were randomly distributed to the three treatment groups. Treatment compounds were numbered 1 , 2 and 3. To minimize confounders, each of the three mice per cage received a different treatment. All clinical and histological investigators were blinded to the treatment until data analysis was finished. For comparability between the therapy groups, all mice, including the CFA control mice, received a daily dose of 1 mg/kg Metacam® (meloxicam) from day 14 after the first immunization on until the end of the experiment. Mice were killed on day 84 of the experiments via intracardiac punction and blood withdrawal under ketamine/xylazine anaesthesia.

Measurement of mouse antibodies by ELISA

ELISA plates were coated with 10Opl per well of either 1 pg/ml bCII (Chondrex, Inc.) or 1 pg/ml hFib (Millipore/Calbiochem) or 1 pg/ml citrullinated hFib (Cayman) or CCP peptide at a concentration of 10 pg/ml in coating solution for 1 h. The CCP peptide we used for the selected CCP assay had the following sequence: HQCHQEST(cit)GRSRGRCGRSGS (SEQ ID NO: 2), with disulphide bonds spanning C3 -C16. All subsequent procedures were performed at room temperature (RT) and incubations were done on a microtiter plate shaker. The coated plates were washed three times with PBST (PBS, 0, 1 % Tween-20), blocked with 100 pi/ well of blocking solution (PBST, 1% BSA) for 1 h, and washed again. Blood serum samples from mice were diluted 1:100 in PBST + 1% BSA and 10Opl were transferred to the blocked ELISA pates and incubated 2 h at RT. After washing with PBST, the ELISA plates were incubated with 100 pl/well of the detection anti-mouse antibody labelled with POD (Jackson Immunoresearch, #715-035-151, 1:10000 dilution in PBST + 1% BSA), for 1 h. After washing, the POD was detected by incubation with 100 pi/ well of TMB substrate (Thermo Scientific, #34029) until a maximal optical density (OD) of about 1 to 2 was reached. Finally, the colorimetric reaction was stopped with 100 pl/well stopping solution (1M H2S04) and the OD determined at a wavelength of 450 nm with a reference wavelength of 595 nm with the Tecan Infinite F 200 plate reader.

Histology

Mice were examined post mortem for macro-anatomical pathology. Then, the right hind paws of the mice were amputated at the level immediately above the external malleolus. The skin was removed and the skinless paws were fixed in 4% paraformaldehyde at 4°C overnight. Decalcification was performed in a mixture solution of 14% EDTA and 4% paraformaldehyde at a ratio of 1 : 1 for one day and subsequently in fresh 14% EDTA alone for 2 more weeks at RT under constant agitation. After this the paws were incubated overnight in a mixture medium of 30% sucrose dissolved in PBS and finally embedded in OCT compound (Tissue-Tek O.C.T. compound; VWR Chemicals, Leuven, Belgium).

Frozen sagittal sections (7pm) were cut in series with an interval of 500 pm using a cryostat (temperature, -19°C; Leica Biosystems, Nussloch, Germany, and Buffalo Grove, IL) and mounted on Trubond microslides (Trubond 380, Catalog no: 63700- W1; Electron Microscopy Sciences; Hatfield, PA 19440; USA). The sections were kept in a freezer at - 80°C until use. There was a total of five sections in each paw to cover the distance from the external to internal malleolus. Sections were stained with hematoxylin and eosin (HE) using standard protocols and were assessed for pathologic changes in the joints under the bright field illumination on a Zeiss upright microscope (Carl Zeiss AG, Oberkochen, Germany) by a blinded investigator.

A histological score was determined using a 0 to 3 scale based on the intensity and extent of change to the ankle and tarsal joints compared to native mice of the same age for each of five categories (score 0= no changes; score 1 = slight change; score 2= moderate change; score 3: marked change). The categories consisted of: inflammation, synovial alterations, cartilage degeneration, pannus formation and bony changes. The histological scores were expressed as the sum of the five categories for each section with a highest score of 15 per slide. The average of the scores of the middle three of five sections represents the histological score of one animal.

Statistical evaluation

Results were compared by analysis of variance (ANOVA) after testing for normal distribution by Kolmogorov-Smirnov ^' s test using SPSS v19. If normal distribution was not present, Mann-Whitney test was used. Kaplan Meier plots were compared by log-rank testing.

RESULTS

Immunization of DBA/1 mice with human Fibrinogen (hFib) and bovine Collagen

(bCII) leads to arthritis in all immunized animals

In a pilot study, 10 DBA/1 mice were immunized according to the immunization scheme described above. Two additional mice which did not receive any immunization but were measured and scored according to the protocol served as native controls. Due to severe affection at the immunization sites, two of the immunized mice had to be euthanized soon after the first injection, and were excluded from analysis so that in the end, a total of 8 immunized mice and 2 native controls were used for evaluation of the experimental model. As shown in Figure 2 A, the mice began to develop signs of arthritis on day 14 of the experiment. On day 56 the prevalence of arthritis reached 100%. The arthritis score was also severe with a maximum mean score of 11.25 on day 70 (Figure 2 B). None of the native control mice developed clinical signs of arthritis.

Paw measurements via a caliper showed significant differences between immunized and native mice. (Figure 2 C). The measured joints, especially the tarsal joints, showed swelling starting on day 28, which was significantly increased between days 56 and 70 until the end of the experiment. These results occurred in parallel to the respective arthritis scores.

Pathology and histology confirmed the clinical findings. The paws showed severe inflammation and ankylosis on all limbs. Figure 2 D shows the marked difference between the hind paws of immunized and native mice. The whole paws of the immunized mice showed severe swelling including tarsal joints and metatarsus. The digits were swollen and ankylosed and the claws were prolonged due to a lack of use and thus, less abrasion. The HE-stained sections of the right hind paws were investigated histologically. The mean histology score of the immunized animals ranged at 6.1 whereas the native mice showed no signs of arthritis (Figure 2 E).

Main findings were inflammation, cartilage erosion, bone alterations and pannus formation. Representative histological images can be seen in Figure 4 - CFA control and CFA + NaCI groups.

The mice developed a strong antibody response to collagen and fibrinogen as well as citrullinated fibrinogen

For assessment of antibodies, various antigens were coated on ELISA plates, and the sera of the mice were added. Binding of antibodies to the antigens was then measured by adding anti-mouse antibodies labelled with POD.

The mice developed a strong antibody response to the immunizing antigens bCII and hFib - the OD-450-values ranged between 1 and 1.4. The mice also developed an immune reaction to citrullinated fibrinogen, though to a lesser extent (OD about 0.5). The native control mice did not develop any of those antibodies (see Figure 3 A). Repeated measurements were carried out for all antibodies, and showed rapid increases of anti-fibrinogen, anti-collagen and anti-citrullinated fibrinogen antibodies to high values after 14 - 35 days, which did not change thereafter. For reasons of clarity, only the values obtained at the final blood sampling at day 84 upon sacrifice are shown.

The sera were tested on ELISA plates that had been coated with one selected CCP peptide. Figure 3 B shows that the antibody levels of the immunized animals reached low, but significantly higher levels than those of the native mice on days 14, 35 and 70. After that the OD values subsided to the same level as the native mice. Administration of peptide 90578 to immunized animals leads to reduced histological signs of arthritis

In a second experiment, FIA-CIA immunized mice were given either peptide 90091 or peptide 90578 at a concentration of 1 mg/kg i.v. into the tail vein on days 14, 35 and 56 after the first immunization. As positive controls, one group of mice received 0.9% NaCI as treatment. In addition, five mice were immunized with CFA/IFA alone at the two injection sites to serve as negative control animals (further referred to as CFA control mice). They did not receive any treatment.

Of the overall 30 FIA-CIA immunized mice, one had to be killed due to severe reaction at the injection site before treatment started and was excluded to the experiment. The remaining 29 mice were randomly distributed to the three treatment groups. Investigators were blinded to the treatments. Of those 29 mice, 6 had to be killed in the course of the experiment and were excluded to the analysis. For data analysis at the end of the experiment the remaining 23 mice were distributed as follows to the three treatment groups: 8 mice each received either peptide 90578 or 90091 and 7 mice received NaCI.

The figures show data from the three different groups. Nearly all immunized animals developed arthritis, most starting between days 21 and 28. There was a significant decrease in the histology score of the 90578-treated group in comparison to the NaCI-treated group. The mice which had been given the peptide 90578 had an average histology score of 3.9, whereas the mice only treated with NaCI had a score of 6.6 (Figure 4 A).

Figures 4 B-M show the differences between the FIE-stained sections of the right hind paws. In the overview of the paws, the differences between CFA control animals and NaCI- and 90091 -treated animals are apparent. The soft tissues around the ankle and metatarsus were severely enhanced in the NaCI-treated mice (Figure 4C) and in the 90091 -treated mice (Figure 4D). In addition, the darker blue staining of the pictures of NaCI- and 90091 -treated mice is due to a massive accumulation of lymphocytes in this region. In contrast to this, the 90578-treated mice showed less tissue enhancement and lymphocyte infiltration (Figure 4E).

Ankle and tarsal joints were investigated in detail (Figure F-M). The NaCI-treated mice showed signs of severe inflammation with lymphocyte infiltrates, cartilage and bone erosion. Pannus formation was also evident. 90091 -treated animals had less lymphocyte infiltrates, but also pannus formation and cartilage erosion. In the 90578-treated animals, the cartilage was intact and there were only a few lymphocyte infiltrates in the subchondral bone. CFA-immunized control mice showed no significant joint alteration.

Figure 5 shows that tarsal joints of mice receiving peptide 90578 had significantly lower swelling on days 49 and 56. The arthritis scores of the group treated with the peptide 90578 tended to be less severe than in mice treated with peptide 90091 or NaCI. Peptide 90091 even seemed to enhance arthritis, but not significantly. None of the CFA control mice showed any clinical signs of arthritis, paw measurements were significantly lower than in FIA-CIA immunized NaCI-treated mice.

Several animals had to be killed before the end of the experiment due to severe arthritis. As soon as an animal did not put weight on a paw anymore, it was euthanized immediately. The survival probability which is shown in the Kaplan-Meier chart in Figure 6 shows the resulting survival rates of each group. In the NaCI- treated group, more and earlier drop outs were observed than in the groups that received peptide 90091 or 90578 as treatments. Statistical analysis based on log- rank testing did not reveal a significant difference between groups, which may be due to low number of cases. None of the CFA control mice had to be killed.

Antibody levels of peptide 90091- and peptide 905778-treated animals were not affected by treatment

Although histological and clinical findings support an effectiveness of peptide 90578 in FIA-CIA mice, this effect could not be found in the antibody levels. In the ELISAs of the sera taken on days 35 and 84 there was no difference in anti-bCII or anti-hFib antibody titers between the three treatment groups. The antibody titers increased to the same levels regardless of treatment.

Discussion

Flere, a mouse RA model is described, in which the administration of a fructosylated peptide derived from bCII reduced clinical disease severity and damage to the joints in histological sections of the paws, when administered IV after disease had been established. These effects were not observed with the non-fructosylated homologous peptide.

The mouse model described here was modified based on the FIA-CIA model published by Flo et al. [27], is highly reproducible and leads to severe arthritis of the paws in 100% of the animals. The mice established an immune reaction and developed antibodies directed to citrullinated fibrinogen as well as to the immunizing antigens. The presence of anti-citrullinated fibrinogen antibodies can be explained by two theories: One is that human fibrinogen gets citrullinated in the course of the preparation, so that the administered fibrinogen already contains citrulline residues, another theory is that the enzyme protein arginine deimidase 4 (PAD-4) that exists in polynuclear cells can citrullinate the peptides in the joints when those cells die and PAD-4 is set free [23] Mass spectrometry showed that human fibrinogen (hFib) derived from Sigma-Aldrich or Calbiochem already contains certain citrulline residues [27] Flowever, the theory that PAD-4 can contribute to arthritis by citrullinating peptides and proteins cannot be dismissed. It has been shown that NETotic and necrotic granulocytes can citrullinate fibrinogen via PAD enzymes [29] Upon immunization with PAD, some mice even developed antibodies against citrullinated fibrinogen [29] Thus, the presence of anti-citrullinated fibrinogen antibodies is likely due to a mix of both those reasons.

Compared to the CFA method described by Ho et al. [27], only a tenth of the Mycobacterium tuberculosis dosage was used (0.05 mg instead of 0.5 mg per injection site) for the first immunization and half of the bCII dosage (0.1 mg per mouse compared to 0.2 mg). Despite the lower doses, the arthritis could be induced with sufficient severity in 100% of the immunized animals. The injection volume of only 50pl per injection site also differs from the description of the CIA model in some publications. Most use an injection volume of 100 mI [19, 31] or a lower volume and instead a higher concentration of mycobacteria in the emulsion [18] Here it is presented that in FIA-CIA, injection volumes of 50 mI and a M. tuberculosis- concentration of 2 mg/ml in CFA is enough to induce a severe arthritis. A reduction of M. tuberculosis in CFA incurs lower risks of severe ulcers or granulomas at the injection sites of the mice [31] , which otherwise can lead to termination of the experiment before arthritis development and a need for more mice due to drop-outs. Although the mice received a daily administration of the COX-2-blocker meloxicam upon development of arthritis, the severity of the arthritis increased even under this treatment. The dose was apparently not sufficient to have an unwanted impact on the joint inflammation, but visibly reduced the pain of the animals. Even the administration of meloxicam before the development of signs of arthritis in the therapy study did not prevent the onset of arthritis and the animals did not develop any adverse effects over the course of the experiment. Meloxicam has the advantage over other recommended analgesics in animal arthritis studies such as buprenorphin or paracetamol (acetaminophen) [30] that it has to be given only once a day, is orally available and has less side effects. Thus, it is proposed to use meloxicam in the pain treatment of rheumatic animals in therapy studies. With regard to the 3Rs in laboratory animal welfare, reduction of the immunization dose and volume as well as application of pain killers should be considered in the refinement of mouse arthritis models. Contrary to the findings of other groups [22, 27], it was not possible to find relevant anti-CCP2 antibody levels, as determined with the commercially available assay in the sera of our mice. These tests showed no difference between immunized and native mice. Anti-CCP assays are used to detect the presence of ACPAs. As seen in the anti-citrullinated fibrinogen ELISA, the mice treated developed antibodies against at least one citrullinated protein. However, those antibodies could not be detected by the commercial anti-CCP2 tests. Also, using an assay with one single CCP coated on ELISA plates slight differences in antibody levels were found at three of six measurement days. Whether this result is due to a low antibody presence against citrullinated peptides in the sera or a difference in anti-CCP antibodies between mice and humans and thus, a low suitability of the tests for mouse studies remains to be elucidated.

The peptide of the invention (“90578”) had a significant effect on the histological outcome of the FIA-CIA in DBA/1 mice. When administered intravenously on three different time points after the first immunization, this peptide led to significantly reduced histological signs of arthritis in the treated animals compared to the control group. Peptides that mimic epitopes of collagen II have been shown to reduce or prevent the development of CIA in mice and rats, when administered before [32-35] or in parallel to the immunization [14, 36, 37] , with an additional MHC-II molecule [15, 16] or by attaching the peptide to an immune or T cell binding peptide [38]

Some authors described oral or nasal administrations of peptides to induce mucosal tolerance [39-41] But they also either applied the peptides before the induction of the arthritis [39, 41] or used additional immune modulators such as a cholera toxin- derived fusion protein [40] Administration of peptides before the induction of arthritis does not replicate the situation found in human RA patients and this may be a critical point in finding new treatment strategies for RA. Also, the addition of molecules such as MHC or cholera toxin-derived proteins to the peptide increases the risk of severe adverse reactions which may be another reason why new treatment strategies subsequently failed in clinical studies in humans.

There are already some descriptions of CIA models in which the administration of modified peptides of collagen with two or three amino acid substitutions after the immunization or even after development of arthritis symptoms resulted in a therapeutic effect in rats [42] or HLA-DR1 transgenic mice [43] In a rat model of adjuvant-induced arthritis (AIA), s.c. injections of a multi-epitope peptide reduced disease severity [17] This peptide also modulated T cell subsets in RA patients ^' peripheral blood cells [44] Also nanoparticles coated with peptides improved disease symptoms in HLA-DR4-IE-transgenic mice or depleted patient specific B cells [45,49] Moreover, it has been shown that cyclic peptides can target RA patients ^' ACPAs ex vivo [46]

It is shown that giving the fructosylated peptide 256-270 of bCII intravenously alone and two weeks after the induction of arthritis can lead to a long term effect in FIA- CIA in mice which is characterized by a significant reduction of histological signs of arthritis in mice. At the time of the first treatment application on day 14, the antibodies against bC II, hFib and citrullinated fibrinogen were already established, while arthritis was not yet prevalent. In human RA, development of autoantibodies against CCP often precedes the onset of arthritis for years [47,48] and antibodies against collagen II are predictive for an early severe course of disease [5] It would be desirable to intervene in the development of the disease so that symptoms can be attenuated or in the best case completely prevented.

An interesting aspect of the results is that the application of certain peptides or proteins works to switch the immune response to tolerance of certain antigens.

There is some evidence that the application of peptides that mimic T cell epitopes can induce regulatory T cells that secrete anti-inflammatory cytokines such as IL-10 and TGF-b and thus lead to a suppression of antigen presenting cells [49] The only difference between the two peptides in this study is the fructosylation of the lysin at position 264 of the 90578 peptide, whereas peptide 90091 is not modified. The glycosylation of Lys 264 is oriented towards the T cell receptor (TCR) and seemingly has the potential to be a major regulator of T cell tolerance. It may be that the glycosylation at lysin 264 of the peptide 90578 leads to a better recognition by T cells and thus to the secretion of more anti-inflammatory cytokines such as IL-10, which then ameliorate the outcome of the arthritis in mice. Interestingly, glycosylation of the specific collagen epitope (aa 256-270) does not only play a role in CIA in mouse strains with the arthritis-susceptible Aq class II gene, but also in transgenic mice expressing human class II molecules associated with RA and in humans with RA [51]

Also for the observed beneficial effects a reduction in T cell infiltration, differences in the migration of different subsets of T cells responding to or producing different cytokines may contribute.

In conclusion, hCII-derived fructosylated peptide 90578 is a promising novel therapeutic approach to treat disease symptoms in FIA-CIA mice and potentially also in humans with RA.

List of Abbreviations:

ACPAs anti-citrullinated peptide antibodies

AIA adjuvant-induced arthritis bCII bovine collagen II

BSA bovine serum albumin

CFA complete Freund ^' s Adjuvant

CCP cyclic citrullinated peptides

DMARDs disease modifying anti-rheumatic drugs

FIA-CIA bCII- and hFib-immunized mice which develop RA-like arthritis

FMOC fluorenylmethoxycarbonyl hFib human fibrinogen

I FA incomplete Freund ^' s adjuvant

IL6R interleukin-6 receptor

MHC II major histocompatibility complex class II

PBS phosphate-buffered saline

RA rheumatoid arthritis

RF rheumatoid factor

TGF-b transforming growth factor beta

TNF tumour necrosis factor