2. BACKGROUND ART Cystatin C, also known as y trace, is a cysteine protegse inhibitor found : in all mammalian body fluids and tissues. Cystatin C is composed of 120 amino-acid residues (Grubb, et al., 1984). A variant of cystatin. C is the major constituent of amyloid deposited in cerebral vasculature of patients with-hereditary cerebral hemorrhage with amyloidosis,-Icetandic type, (HCHWA-I) resulting in hemorrhagic strokes early in life.

Cystatin C has a broad spectrum of biological roles including, but not limited to,-bone resorption, modulation of inflammatory responses, stimulation of glomerular mesangial cell proliferation, modulation of neuropeptide activation and degradation, neurite proliferation, and neuronal protection and survival. Cystatin C is found in all body fluids at significant concentrations, and has particularly high levels in seminal plasma (-50 mg/l or 3. 7 µM) and cerebrospinal fluid (-5. 8 mg/i or 0.43 I1M). It is a potent inhibitor of papain-like peptidases and is considered a major, general extracellular cysteine protease inhibitor. However, there is data placing cystatin C and its inhibitory activity also intracellularly.

Cystatin C has a role in Alzheimer's disease (AD). Genetic data demonstrate linkage of the cystatin C gene (CST3), localized on t AD. Patients with AD, Down's syndrome, cerebral amyloid angiopathy (CAA) and hereditary cerebral hemorrhage with amyloidosis, Dutch type (HCHWA-D), and normally aging individuals have amyloid in cerebral vessel walls, which is mainly composed of amyloid (3 (Ap). The load of amyloid deposition in the vessel walls varies - between individuals. Cerebrovascular deposits of amyloid are generally asymptomatic, but in advanced cases, they can lead to vessel rupture and hemorrhage. Progression from asymptomatic to advanced CAA reflects progressive accumulation of amyloid in vessels. However, only a small percentage of individuals with high load of CAA develop cerebral hemorrhage. Thus, in these individuals, CAA appears to be a prerequisite, but not sufficient for vessel rupture. This suggests that factors, other than the amyloid load cause the damage to the vessel walls.

Immunohistochernicál studies of brains of patients with AD, Down's syndrome, CAA and HCHWA-D, reveal the co-localization of cystatin C with AD predominantly in amyloid-laden vascular walls, and in senile plaque cores of amyloid. It has been advanced that cystatin C deposition occurs secondarily to AD and increases : the propensity to cerebral hemorrhages. While high Ap toad was found to be a risk factor for the occurrence of hemorrhage, strong cystatin C immunostaining was a risk factor for both occurrence and enlargement of the hemorrhage, and tendency to have recurrent strokes. Thus, cystatin C can be a factor contributing to hemorrhage in patients with AD amyloid deposits in cerebral vasculature.

In vitro analysis of the association between cystatin C and P amyloid precursor protein (ßAPP) reveal binding between the two proteins and that this binding does not affect the level of AD secretion. Transgenic mice have been created that express either human wild type or the HCHWA-I variant cystatin. C under control sequences of the human cystatin C gene.

Analysis of Ap40 and Ap42 concentrations in the brain of these mice show no difference between transgenic mice and their non-transgenic littermates. Thus, in vivo over expression of human cystatin C does not affect AD levels in mice that do not deposit Ap.

Furt'he'rmbre,'cy'st'atin"C binding to Ap was demonstrated, and this binding inhibits fibril formation. Assays using a GST-Aß fusion protein and media of cells transfected with either wild type or variant cystatin C genes reveal binding of cystatin C to the fusion protein. Analysis of the association of cystatin C and Ap by ELISA demonstrate that cystatin C interacts with both Aß40 and Ap42 in a concentration dependent manner at physiologic pH and temperature. Specific, saturable, and high affinity binding between cystatin C and Ap has been observed. Electron microscopical analysis of fibril formation reveals that incubation of cystatin C with Ap inhibits Ap fibril formation in a concentration dependent manner.

As a result of crossing cystatin C transgenic mice with transgenic mice over expressing ßAPP, studies for the role of cystatin C in AD and CAA have been accomplished. Specifically, a transgenic mouse expressing ßAPP driven by neuron-specific Thy1. 1 transgenesis cassette (APP23) can be used to study these diseases. These mice demonstrate age dependent deposition of Ap in the neuropil as well as in cerebral blood vessels. The level of CAA in these mice increases extensively upon aging.

Incidences of hemorrhages occur in very old mice. Amyloid deposition in the neuropil also occurs in the brains of Tg2576 transgenic mice, however, CAA occurs to a lesser degree. Studies have demonstrated significant decrease in plaque load in the brains of double positive mice for the cystatin C and ßAPP genes compared with mice single positive for the ßAPP gene. This demonstrates in vivo inhibition of amyloid fibril deposition.

In addition, using Western blot analysis it has been found that a clear difference exists in mobility of cystatin C from brain homogenates between controls and patients with different stages of AD, including patients with mild cognitive impairment (CDR 0.0-0. 5). Using anti-cystatin C antibody, it has been discovered that in addition to the monomeric 14 kDa cystatin C, a band of about 17 kDa only in control individuals exists. A - band of the same molecular weight was stained also with anti-Ap antibody only in control brains, suggesting that this band can be cystatin C bound to Ap. This suggests that cystatin C can also be used as a marker

differentiating disease cases and controls. The fact that there is a difference in a very early stage of the disease is particularly important, because of the need in a method for early detection of the disease.

Immunohistochemical studies of brains of individuals with AD, Down's syndrome, CAA, and HCHWA-D, have also revealed the co- localization of cystatin C with Ap predominantly in amyloid-laden vascular walls, and in senile plaque cores of amyloid. The risk of cerebral hemorrhage increases when high levels of cystatin C are co-deposited with Ap in cerebrovascular amyloid deposits. There are at least two indications that cystatin C is present in amyloid deposits composed of amyloid proteins, other than Ap. An immunohistochemical study of the brain of a ; patient with familial cerebral amyloid angiopathy, British type, reveals staining with anti-cystatin C antibody, suggesting that cystatin C co- deposits with the amyloid peptide. Furthermore, we have data showing staining with anti-cystatin C antibodies of amyloid deposits in patients with prion deposits such as GSS or CJD. Thus, cystatin C is a factor contributing to hemorrhage in patients with a variety of amyloid deposits in cerebral vasculature.

Furthermore, high concentrations of cystatin C cause hemorrhages in the absence of fibrilla deposits. High systemic concentrations of cystatin C were found in several human diseases, including diabetic nephropathy, hypertension, coronary heart disease and obesity, all conditions that are risk factors for intracerebral hernorrhage. The relationship between elevated circulatory cystatin C concentration and the risk for hemorrhage is supported by the occurrence of hemorrhages in cystatin C transgenic mouse lines, generated in our laboratory. Thus, cystatin C can also contribute or cause stroke, in the absence of amyloid deposition.

Accordingly, there is a need for a method and composition for inhibiting amyloid fibril formation. Amyloid fibril formation is inhibited by cystatin C or other similar peptide. Therefore, there is also a need for compositions that mimic cystatin C or a fragment of cystatin C capable of inhibiting or preventing fibril formation and/or deposition. Additionally, there is a need for a substance, composition, and method of treatment for

preventing and/or treating hemorrhages.

SUMMARY OF THE INVENTION The present invention provides a method of treating amyloidoses by administering an effective amount of a cystatin C composition or by increasing protein expression of cystatin C. Furthermore, there is provided a method of preventing fibril formation or deposition by administering an effective amount of a cystatin C composition or by binding amyloid proteins with an effective amount of a cystatin C composition. In addition, the present invention provides a composition for treating amyloidoses or for preventing fibril formation or deposition including an effective amount of a cystatin C composition. The present invention also provides a method of preventing or treating hemorrhages by preventing or inhibiting local or systemic accumulation of cystatin C. Also provided is a method of preventing or treating hemorrhages by preventing or inhibiting binding of cystatin C to specific blood vessel walls components, to cells that compose the blood vessel walls such as endothelial and smooth muscle cells, and to cell surface proteins associated with amyloid deposits.

Further, the present invention provides a method of preventing or treating hemorrhages by blocking or altering cell surface markers associated with cystatin C peptides, preventing or inhibiting binding of cystatin C to components of the blood such as proteins, lipids, or cells, and preventing inhibition of proteases in the circulation (e. g. , cathepsin B, H, or L as a result of high levels of their inhibitor cystatin C). The present invention also provides a composition for preventing or treating hemorrhages including a peptide that competes with cystatin C binding with cell surface proteins associated with amyloid deposits. Finally, the present invention provides a composition for prevention or treating hemorrhages in the absence of amyloid deposits by inhibiting the binding or activity of cystatin C.

BRIEF DESCRIPTION OF THE DRAWINGS Other advantages of the present invention will be readily

appreciated, as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings.

Figure 1A illustrates colocalization of cystatin C with ßAPP in transfected cells. Indirect immunofluorescence staining of HEK293 cells stably transfected with wild type cystatin C and transient transfected with ßAPP (A-C) and N2a cells transiently cotransfected with ßAPP and cystatin C (D-l). Cells were stained with monoclonal anti-ßAPP 22C11 antibody (green) and polyclonal anti-cystatin C antibody (red) (Bars represent 10 , um).

Figure 2 illustrates cell surface calocalization of cystatin C with ßAPP in transfected cells. Cell surface staining of N2a cells transiently cotransfected with APP and either wild type cystatin C (A-F) or variant cystatin-C (G-l). Live cells were incubated with monoclonal anti-ßAPP 22C11 antibody (green) and polyclonal anti-cystatin C antibody (red) at 4°C (A-C and G-I) or 37°C (D-F) (Bars represent 10 um).

Figure 3 illustrates binding of cystatin C to ßAPP in conditioned media of HEK293 cells stably expressing either wild type or variant cystatin C DNA (cystatin C-W or cystatin C-V, respectively) that were transiently transfected with either LAPP or vector cDNAs. Imunoblot analysis with 22C11 of cell lysate proteins and of media proteins, the latter immunoprecipitated with anti-cystatin C antibody. Molecular mass standards, in kilodaltons (kDa), are shown on the right.

Figure 4 illustrates determination of the cystatin C binding site within (3APP, using deletion mutants of LAPP. HEK293 cells stably expressing cystatin C DNA were transiently transfected with ßAPP cDNAs.

Immunoblot analysis with 22C11 (left panels) or 369 (right panels) of cell lysat proteins (upper panels) or cell lysate proteins immunoprecipitated with anti-cystatin C antibody (lower panels). Molecular mass standards, in kilodaltons (kDa), are shown on the right.

Figure 5 illustrates that association of cystatin C with ßAPP results in increased spAPPa secretion. Temporal profile of (3APP turnover and spAPPa secretion by N2a cells stably transfected with ßAPP and

transiently transfected with either cystatin C or vector cDNAs. Mean and standard deviation from four different experiments are presented. Symbols represent cells cotransfected with ßAPP and either vector (O), wild type cystatin C (y) or variant cystatin C (A).

Figure 6 demonstrates that coexpressing cystatin C and (3APP does not affect Ap secretion. N2a cells were transiently cotransfected with (3APP and either wild type or variant cystatin C (cystatin C-W or cystatin C- V, respectively) or vector cDNAs. Data is the mean +/-S. E. of three independent experiments with each ELISA measurement determined in duplicate.

Figure 7 illustrates binding of cystatin C to Ap. Immunoblot analysis with anti-cystatin C antibody of media proteins bound to a GST-Api-42, fusion protein. Media of HEK293 cells transfected with either wild type or variant cystatin C (cystatin C-W or cystatin C-V, respectively), or vector cDNA, were used. Arrow marks the bands representing cystatin C. The higher molecular weight bands derive from cross-reaction of the antibody with the fusion proteins. Molecular mass standards, in kilodaltons (kDa), are shown on the right.

Figure 8 demonstrates binding of cystatin C to Ap studied by ELISA.

Variable concentrations of either wild type (solid line, solid circles), variant (dashed line, open squares) or urinary cystatin C (dotted-line, solid triangles) were incubated with either Api-40 or Api-42 coated wells for 3 hours at 37°C. Bound cystatin C was detected with anti-cystatin C antibody, followed by horseradish peroxidase-labeled anti-rabbit IgG.

Means and standard deviations were calculated from three independent duplicate experiments.

Figure 9 demonstrates that monoclonal antibody 6EI0, which binds to residues 1-17 of Ap, abolished cystatin C binding to Ap-coated plates.

Variable concentrations of 6EI0 together with 10 nM urinary cystatin C were incubated with either Api-4o-coated (0) or Aß1 42-coated (y) wells for 3 hours at 37°C. Bound cystatin C was detected with anti-cystatin C antibody, followed by horseradish peroxidase-labeled anti-rabbit IgGa Percentage of cystatin C bound was calculated.

Figure"'10'ittustrates that cystatin C inhibits AP fibril formation.

Electron micrographs of assemblies formed by (A) Ap42 (1 ug) or (B) Ap42 (1 ug) incubated with cystatin C (2 IJg). Scale bars represent 100 nm.

Figure 11 is a table illustrating that cystatin C binding to Ap inhibits Ap fibril formation.

Figure 12 is a picture of an polyacrylamide gel electrophoresis identifying founders of cystatin C transgenic mouse lines by PCR analysis, wherein amplification products of potential founders of CysC-V transgenic lines (lanes 1-11) and minus (-) and plus (+) represent negative and positive controls, respectively.

Figure 13-illustrates a western blot analysis of cystatin C in brain homogenates of 3-month old offspring of five founders of CysC-V transgenic lines. M-olecular mass markers are indicated on the right (in . kDa).

Figure 14 demonstrates that overexpression of cystatin C in transgenic mice does not affect A (3 production. The concentrations of Aß40 and Aß42 are presented in fmol/g wet brain as mean SE for four transgenic or four non-transgenic mice, 3-8 months of age, with each ELISA measurement determined in duplicate.

Figure 15 illustrates immunostaining with 6E10 antibody of brain sections of offspring of a ßAPP mouse crossbred with a CysC-V transgenic mouse (12 months old mice). A double transgenic mouse (APP23+/- /CysC+) is compared to a cystatin C single transgenic (APP23-/-/CysC+) and to ßAPP single transgenic (APP23+/-/CysC-).

Figure 16 shows plaque area (%) in frontal cortex of APP23+/CC+ mice (n=14) (left) or APP23+/CC-mice (n=10) (right). Brain sections were stained with antibodies to Ap42, Ap40 or 6E10, or with thioflavin S.

Figure 17 is a bar graph illustrating human Aß40 and Aß42 in 49-52 month old ßAPP x CysC crosses.

Figure 18 are pictures of cerebral hemorrhages in wild type and variant cystatin C transgenic mice. Subarachnoid hemorrhages in a CysC- V-F6 mouse that died at 13 months of age. Cross sections of this brain revealed an additional, recent, space-occupying hematoma (a, b). Old

'cort ! cat nucrohemorrhages) n the CysCw F6 mouse shown in (a) as revealed by Perls'iron staining (c). Recent, large intracerebral hemorrhages in CysC-V-F6 (d) and CysC-W-F8 (e) mice that died at 18 and 16 months of age respectively, as revealed by hematoxylin-eosin.

Infiltration of a lateral ventricle by lymphocytes and mononuclear cells in a CysC-V-M11 mouse that died at 16 month of age, stained by hematoxylin- eosin (f). Scale bars represent 100 nm.

DETAILED DESCRIPTION OF THE INVENTION Generally, the present invention provides a composition and related methods for treating various diseases including, but not limited to, AD, Down syndrome, hereditary cerebral hemorrhage with amyloidosis, Dutch type, and the like. The present invention is useful in preventing, inhibiting, ameliorating, and/or treating diseases caused by amyloid fibril formation and/or deposition on vessel walls. Further, the present invention is useful in preventing or treating hemorrhages.

The present invention is based on the role of cystatin C in inhibiting amyloid fibril formation and/or deposition. Genetic and immunohistochemical studies demonstrate a role for cystatin C in AD and other related disorders. It has been proves that patients with AD, Down syndrome, hereditary cerebral hemorrhage with amyloidosis, Dutch type have amyloid, composed mainly of A, ß, in their neuropil and cerebral vessel walls. The existence of amyloid in the brain is a cause of these diseases and therefore elimination or reduction of amyloid can lead to treatment of these diseases. The present invention provides a treatment of these diseases whereby overexpression and/or administration of cystatin C or other related peptides that mimic cystatin C structure and function, can be used for prevention and/or treatment of these diseases. Cystatin C is the first protein described that does not affect the production and/or secretion of amyloid, but prevents the formation of the fibrilla, neurotoxic form of the peptide. Furthermore, binding of cystatin C to a soluble amyloid protein such as Ap can prevent the toxicity recently attributed to such proteins.

Cystatin C associates to other amyloid proteins and thus, cystatin C

can be used for the prevention and/or treatment of other amyloidoses.

Cystatin C is a ubiquitously expressed protein with multiple functions.

Manipulation of cystatin C level of expression, either systemically or locally, can provide the desired effect of treating and/or preventing various diseases. Alternatively, a peptide similar to cystatin C can be designed, which mimics the functional properties of cystatin C in relation to amyloid proteins.

As used herein, the term"cystatin C"includes the entire cystatin C peptide, a fragment thereof, or moiety thereof. Moreover, cystatin C can be either in its naturally occurring or synthetic form. Basically, any compound, peptide, peptide fragment, or any other similar substance that mimics the effective portion of cystatin C that inhibits fibril formation and/or deposition or can bind to cystatin C associated proteins can be used with the present invention.

In one embodiment of the present invention, there is provided a method of treating diseases including, but not limited to, AD, Down syndrome, hereditary cerebral hemorrhage with amyloidosis, Dutch type, and any other similar amyloidoses known to those of skill in the art. The method includes administering a therapeutical effective amount of a cystatin C composition. The cystatin C composition includes compounds such as, but not limited to, a natural cystatin C peptide, a synthetic cystatin C peptide, fragments thereof, moieties thereof, cysteine protease inhibitors, any substance that mimics the effective portion of cystatin C, and combinations thereof.

In another embodiment of the present invention, there is provided a composition including a therapeutically effective amount of a cystatin C composition. The cystatin C composition is, but not limited to, an effective portion of cystatin C that inhibits fibril formation and/or deposition. The cystatin C can be the entire cystatin C peptide, a fragment thereof, or a moiety thereof. The cystatin C can be either a natural or a synthetic form of cystatin C. Further, a cysteine protease inhibitor or any other similar inhibitor known to those of skill in the art can be used with the present invention. For example, two other protease inhibitors, a1-antichymotrypsin

and a2-màctrölòbuliin cä bE'used with the present invention since they can bind to Ap and can inhibit fibril formation. Basically, any compound, peptide, peptide fragment, or any other similar substance that mimics the effective portion of cystatin C that inhibits fibril formation and/or deposition can be used with the present invention. In a further embodiment of the present invention, cystatin C can also be used as a rnarker for amyloidosis, detecting very early stages of diseases such as AD.

In other embodiments of the present invention, there is provided compositions and related methods for preventing and/or treating hemorrhages. The methods relate to inhibiting the binding of cystatin C.

Preventing local (tissue specific) or systemic accumulation of cystatin C can be accomplished with the present invention, which results in preventing and/or treating hemorrhages.

Since hemorrhages occur in all types of tissues and organs, the present invention can be used in any tissue type or organ including, but not limited to, brain, kidney, heart, lungs, ovaries, testicles, spleen, liver, and the like. The present invention also can be utilized to treat numerous disorders associated with hemorrhages occurring in various tissues or organs. Further, the present invention can be used to treat any animal species or humans.

, In one embodiment of the present invention, there is provided a composition for inhibiting the binding of cystatin C to specific blood vessel wall components, cell surface proteins, proteins within vessel wall cells such as endothelial or smooth muscle cells, or other proteins that are bound to amyloid deposits mainly in vessel walls. In another embodiment of the present invention, there is provided a method of preventing or treating hemorrhages by blocking or altering cell surface markers associated with cystatin C peptides. In any of these methods, a naturally occurring or synthetic peptide (full-length or fragment) could be used that is sufficient to bind, and if in excess, compete with full-length cystatin C for the binding to vessel wall proteins. Alternatively, fragments within cystatin C can be blocked or altered to prevent binding of cystatin C with vessel wall proteins. Amino acid sequences within cystatin C responsible for the

"binding to otherproteis"'caii"'also be blocked or altered to prevent binding of cystatin C with vessel wall proteins. Moreover, the tertiary or secondary structure of cystatin C can be altered to prevent functionality of the protein thereof. Similarly, amino acid sequences within cystatin C can be blocked or altered, or tertiary or secondary structure of the protein can be altered to prevent its specific cysteine protease inhibitory activity that can be causing hemorrhages.

In yet another embodiment of the present invention, there is provided a method of preventing or treating hemorrhages by preventing or inhibiting binding of cystatin C to components of the blood, such as proteins, lipids, or cells. Furthermore, there is provided a method of preventing or treating hemorrhages by preventing inhibition of proteases in the circulation such as cathepsin B, H or L as a result of high levels of their inhibitor cystatin C. Again, a naturally occurring or synthetic peptide (full- length or fragment) could be used that is sufficient to bind, and if in excess, compete with full-length cystatin C for the binding to vessel wall proteins.

Alternatively, fragments within cystatin C can be blocked or altered to prevent binding of cystatin C with vessel wall proteins. Amino acid sequences within cystatin C responsible for the binding to other. proteins can also be blocked or altered to prevent binding of cystatin C with vessel wall proteins. Moreover, the tertiary or secondary structure of cystatin C can be altered to prevent functionality of the protein thereof. Similarly, amino acid sequences within cystatin C can be blocked or altered, or tertiary or secondary structure of the protein can be altered to prevent its specific cysteine protease inhibitory activity that can be causing hemorrhages.

Finally, the present invention provides a composition for prevention or treating hemorrhages in the absence of amyloid deposits by inhibiting the binding or activity of cystatin C. This can occur by using a naturally occurring or synthetic peptide (full-length or fragment) could be used that is sufficient to bind, and if in excess, compete with full-length cystatin C for the binding to vessel wall proteins. Alternatively, fragments within cystatin C can be blocked or altered to prevent binding of cystatin C with vessel

"with proteins. Amino acid sequences within cystatin C responsible for the binding to other proteins can also be blocked or altered to prevent binding of cystatin C with vessel wall proteins. Moreover, the tertiary or secondary structure of cystatin C can be altered to prevent functionality of the protein thereof. Similarly, amino acid sequences within cystatin C can be blocked or altered, or tertiary or secondary structure of the protein can be altered to prevent its specific cysteine protease inhibitory activity that can be causing hemorrhages.

In another embodiment of the present invention, modulation of a signal transduction activity of a related receptor protein can occur. This can occur through the activation or inactivation of enzymes that can alter phosphorylation patterns or other post-translational modifications.

Additionally, modulation can occur through activation or inhibition of proteases, activation of ion channels or intracellular ion stores, effector enzyme activation via guanine nucleotide binding protein intermediates, formation of inositol phosphate, activation or inactivation of adenylyl cyclase, and direct activation (or inhibition) of a transcriptional factor and/or activation.

In a further embodiment, there is provided a method of preventing or inhibiting local or systemic accumulation of cystatin C. Local or systemic accumulation of cystatin C can be prevented or inhibiting utilizing any of the methods disclosed herein.

In another embodiment of the present invention, a cystatin C modifying compound can be used. Thus, hemorrhages can be prevented or treated by preventing or inhibiting local or systemic accumulation of cystatin C. This can occur by modifying cystatin C production. A cystatin C modifying compound is any compound capable of modifying cystatin C production. For example, the compound can be a gene therapy composition that either increases or decreases cystatin C production dependent upon the treatment, such as cDNA, RNA, m RNA, cRNA, and tRNA. Additionally, the compound can be cystatin C, thus eliminating the need to include a compound that can increase the production of cystatin C.

When cysfatin !'n C"is beTh'g"administered it can be administered as a cDNA sequence, and analogs thereof or the protein encoded by the sequence.

Gene therapy, as used herein, refers to the transfer of genetic material (e. g. DNA or RNA) of interest into a host to treat or prevent a genetic or acquired disease or condition phenotype. The genetic material of interest encodes a product (e. g. a protein, polypeptide, peptide, functional RNA, antisense) whose production in vivo is desired. For example, the genetic material of interest can encode a hormone, receptor, enzyme, polypeptide, or peptide of therapeutic value. Alternatively, the genetic material of interest can encode a suicide gene. For a review see, in general, the text"Gene Therapy" (Advances in Pharmacology 40, Academic Press, 1997).

Two basic approaches to gene therapy have evolved : (1) ex vivo and (2) in vivo gene therapy. In ex vivo gene therapy cells are removed from a patient, and while being cultured are treated in vitro. Generally, a functional replacement gene is introduced into the cell via an appropriate . gene delivery vehicle/method (transfection, transduction, homologous recombination, etc. ) and an expression system as needed and then the modified cells are expanded in culture and returned to the host/patient.

These genetically reimplanted cells have been shown to express the transfected genetic material in situ.

In in vivo gene therapy, target cells are not removed from the subject rather the genetic material to be transferred is introduced into the cells of the recipient organism in situ that is within the recipient. In an alternative embodiment, if the host gene is defective, the gene is repaired in situ [Culver, 1998]. These genetically altered cells have been shown to express the transfected genetic material in situ.

The gene expression vehicle is capable of delivery/transfer of heterologous nucleic acid into a host cell. The expression vehicle can include elements to control targeting, expression and transcription of the nucleic acid in a cell selective manner as is known in the art. It should be noted that often the 5'UTR and/or 3'UTR of the gene can be replaced by the 5'UTR and/or 3'UTR of the expression vehicle. Therefore as used

'herein'th'e""'expre'ssi0n""vehicte can, as needed, not include the 5'UTR and/or 3'UTR of the actual gene to be transferred and only include the specific amino acid coding region.

The expression vehicle can include a promoter for controlling transcription of the heterologous material and can be either a constitutive or inducible promoter to allow selective transcription. Enhancers that can be required to obtain necessary transcription levels can optionally be included. Enhances are generally any non-translated DNA sequence that works contiguously with the coding sequence (in cis) to change the basal transcription level dictated by the promoter. The expression vehicle can also include a selection gene as described herein below.

Vectors can be introduced into cells or tissues by any one of a variety of known methods within the art. Such methods can be found generally described in Sambrook et al., Molecular Cloning : A Laboratory Manual, Cold Springs Harbor Laboratory, New York (1989,1992), in Ausubel et al., Current Protocols in Molecular Biology, John Wiley and Sons, Baltimore, Maryland (1989), Chang et al., Somatic Gene Therapy, CRC Press, Ann Arbor, MI (1995), Vega et al., Gene Targeting, CRC Press, Ann Arbor, MI (1995), Vectors : A Survey of Molecular Cloning Vectors and Their Uses, Butterworths, Boston MA (1988) and Gilboa et al (1986) and include, for example, stable or transient transfection, lipofection, electroporation, and infection with recombinant viral vectors. In addition, see United States patent 4,866, 042 for vectors involving the central nervous system and also United States patents 5,464, 764 and 5,487, 992 for positive-negative selection methods.

Introduction of nucleic acids by infection offers several advantages over the other listed methods. Higher efficiency can be obtained due to their infectious nature. Moreover, viruses are very specialized and typically infect and propagate in specific cell types. Thus, their natural specificity can be used to target the vectors to specific cell types in vivo or within a tissue or mixed culture of cells. Viral vectors can also be modified with specific receptors or ligands to alter target specificity through receptor mediated events.

A specmc example of DNA viral vector for introducing and expressing recombinant sequences is the adenovirus-derived vector Adenop53TK. This vector expresses a herpes virus thymidine kinase (TK) gene for either positive or negative selection and an expression cassette for desired recombinant sequences. This vector can be used to infect cells that have an adenovirus receptor that includes most cancers of epithelial origin as well as others. This vector as well as others that exhibit similar desired functions can be used to treat a mixed population of cells and can include, for example, an in vitro or ex vivo culture of cells, a tissue or a human subject.

Additional features can be added to the vector to ensure its safety and/or enhance its therapeutic efficacy. Such features include, for example, markers that can be used to negatively select against cells infected with the recombinant virus. An example of such a negative selection marker is the TK gene described above that confers sensitivity to the antibiotic gancyclovir. Negative selection is therefore a means by which infection can be controlled because it provides inducible suicide through the addition of antibiotic. Such protection ensures that if, for example, mutations arise that produce altered forms of the viral vector or recombinant sequence, cellular transformation can not occur.

Features that limit expression to particular cell types can also be included. Such features include, for example, promoter and regulator elements that are specific for the desired cell type.

In addition, recombinant viral vectors are useful for in vivo expression of a desired nucleic acid because they offer advantages such as lateral infection and targeting specificity. Lateral infection is inherent in the life cycle of, for example, retrovirus and is the process by which a single infected cell produces many progeny virions that bud off and infect neighboring cells. The result is that a large area becomes rapidly infected, most of which was not initially infected by the original viral particles. This is in contrast to vertical-type of infection in which the infectious agent spreads only through daughter progeny. Viral vectors can also be produced that are unable to spread laterally. This characteristic can be useful if the

>dësivet is to introduce a specified gene into only a localized number of targeted cells.

As described above, viruses are very specialized infectious agents that have evolved, in many cases, to elude host defense mechanisms.

Typically, viruses infect and propagate in specific cell types. The targeting specificity of viral vectors utilizes its natural specificity to specifically target predetermined cell types and thereby introduce a recombinant gene into the infected cell. The vector (s) to be used in the methods of the invention depends on desired cell type to be targeted and are known to those skilled in the art. For example, if breast cancer were to be treated then a vector specific for such epithelial cells would be used. Likewise, if diseases or pathological conditions of the hematopoietic system were to be treated, then a viral vector that is specific for blood cells and their precursors, preferably for the specific type of hematopoietic cell, would be used.

Retroviral vectors can be constructed to function either as infectious particles or to undergo only a single initial round of infection. In the former case, the genome of the virus is modified so that it maintains all the necessary genes, regulator sequences and packaging signals to synthesize new viral proteins and RNA. Once these molecules are synthesized, the host cell packages the RNA into new viral particles that are capable of undergoing further rounds of infection. The vector's genome is also engineered to encode and express the desired recombinant gene. In the case of non-infectious viral vectors, the vector genome is usually mutated to destroy the viral packaging signal that is required to encapsulate the RNA into viral particles. Without such a signal, any particles that are formed will not contain a genome and therefore cannot proceed through subsequent rounds of infection. The specific type of vector will depend upon the intended application. The actual vectors are also known and readily available within the art or can be constructed by one skilled in the art using well-know methodology.

The recombinant vector can be administered in several ways. If viral vectors are used, for example, the procedure can take advantage of their target specificity and consequently, do not have to be administered

locally at the diseased site. However, local administration can provide a quicker and more effective treatment, administration can also be performed by, for example, intravenous or subcutaneous injection into the subject.

Injection of the viral vectors into a spinal fluid can also be used as a mode of administration, especially in the case of neuro-degenerative diseases.

Following injection, the viral vectors will circulate until they recognize host cells with the appropriate target specificity for infection.

An alternate mode of administration can be by direct inoculation locally at the site of the disease or pathological condition or by inoculation into the vascular system supplying the site with nutrients or into the spinal fluid. Local administration is advantageous because there is no dilution effect and, therefore, a smaller dose is required to achieve expression in a majority of the targeted cells. Additionally, local inoculation can alleviate the targeting requirement required with other forms of administration since a vector can be used that infects all cells in the inoculated area. If expression is desired in only a specific subset of cells within the inoculated area, then promoter and regulator elements that are specific for the desired subset can be used to accomplish this goal. Such non-targeting vectors can be, for example, viral vectors, viral genome, plasmids, : phagemids and the like. Transfection vehicles such as liposoms can also be used to introduce the non-viral vectors described above into recipient cells within the inoculated area. Those of skill in the art know such transfection vehicles.

The composition of the present invention is administered and dosed in accordance with good medical practice, taking into account the clinical condition of the individual patient, the site and method of administration, scheduling of administration, patient age, sex, body weight and other factors known to medical practitioners. The pharmaceutically"effective amount"for purposes herein is thus determined by such considerations as are known in the art. The amount must be effective to achieve improvement including but not limited to improved survival rate or more rapid recovery, or improvement or elimination of symptoms and other

"ina'icafors'as'are seiected'"appropriate measures by those skilled in the art.

In the method of the present invention, the composition of the present invention can be administered in various ways. It should be noted that it can be administered as the compound or as pharmaceutically acceptable salt and can be administered alone or as an active ingredient in combination with pharmaceutical acceptable carriers, diluents, adjuvants and vehicles. The composition can be administered orally, subcutaneously or parenterally including intravenous, intraarterial, intramuscular, intraperitoneally, and intranasal administration as well as intrathecal and infusion techniques. Implants of the composition is also useful. The patient being treated is a warm-blooded animal and, in particular, mammals including man. The pharmaceutical acceptable carriers, diluents, adjuvants and vehicles as well as implant carriers generally refer to inert, non-toxic solid or liquid fillers, diluents or encapsulating material not reacting with the active ingredients of the invention.

It is noted that humans are treated generally longer than the mice or other experimental animals exemplified herein which treatment has a length proportional to the-length of the disease process and drug effectiveness. The doses can be single doses or multiple doses over a period of several days, but single doses are preferred.

When administering the composition of the present invention parenterally, it is generally formulated in a unit dosage injectable form . (solution, suspension, emulsion). The pharmaceutical formulations suitable for injection include sterile aqueous solutions or dispersions and sterile powders for reconstitution into sterile injectable solutions or dispersions. The carrier can be a solvent or dispersing medium containing, for example, water, ethanol, polyol (for example, glycerol, propylene glycol, liquid polyethylene glycol, and the like), suitable mixtures thereof, and vegetable oils.

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. Nonaqueous vehicles

such a cottonseed oil, sesame oil, olive oil, soybean oil, corn oil, sunflower oil, or peanut oil and esters, such as isopropyl myristate, can also be used as solvent systems for compound compositions. Additionally, various additives which enhance the stability, sterility, and isotonicity of the compositions, including antimicrobial preservatives, antioxidants, cheating agents, and buffers, can be added. Prevention of the action of microorganisms can be ensured by various antibacterial and antifungal agents, for example, parabens, chlorobutanol, phenol, sorbic acid, and the like. In many cases, it will be desirable to include isotonic agents, for example, sugars, sodium chloride, and the like. Prolonged absorption of the injectable pharmaceutical form can be brought about by the use of agents delaying absorption, for example, aluminum monostearate and gelatin. According to the present invention, however, any vehicle, diluent, or additive used would have to be compatible with the compounds.

Sterile injectable solutions can be prepared by incorporating the compounds utilized in practicing the present invention in the required amount of the appropriate solvent with various other ingredients, as desired.

A pharmacological formulation of the present invention can be administered to the patient in an injectable formulation containing any compatible carrier, such as various vehicle, adjuvants, additives, and diluents ; or the composition utilized in the present invention can be administered parenterally to the patient in the form of slow-release subcutaneous implants or targeted delivery systems such as monoclonal antibodies, vectored delivery, iontophoretic, polymer matrices, liposomes, microspheres and nanospheres. Examples of delivery systems useful in the present invention include. 5,225, 182; 5,169, 383; 5,167, 616; 4,959, 217; 4,925, 678; 4,487, 603; 4,486, 194; 4,447, 233; 4,447, 224; 4,439, 196; and 4,475, 196. Many other such implants, delivery systems, and modules are well known to those skilled in the art.

A pharmacological formulation of the composition utilized in the present invention can be administered orally to the patient. Conventional methods such as administering the composition in tablets, suspensions,

"solutions, emulsions,'capsules, powders, syrups and the like are usable.

Known techniques that deliver it orally or intravenously, and retain the biological activity are preferred.

In one embodiment, the composition of the present invention can be administered initially by intravenous injection to bring blood levels to a suitable level. An oral dosage form then maintains the patient's composition levels. Additionally, other forms of administration, dependent upon the patient's condition and as indicated above, can be used. The quantity to be administered will vary for the patient being treated and will vary from about 100 ng/kg of body weight to 100 mg/kg of body weight per day and preferably will be from 1 mg/kg to 10 mg/kg per day.

The invention is further described in detail by reference to the following experimental examples. These examples are provided for the purpose of illustration only, and are not intended to be limiting unless otherwise specified. Thus, the invention should in no way be construed as being limited to the following examples, but rather, should be construed to encompass any and all variations which become evident as a result of the teaching provided herein.

EXAMPLES MATERIALS AND METHODS : General methods in molecular bioloav : Standard molecular biology techniques known in the art and not specifically described were generally followed as in Sambrook et al., Molecular Cloning : A Laboratory Manual, Cold Spring Harbor Laboratory Press, New York (1989), and in Ausubel et al., Current Protocols in Molecular Biology, John Wiley and Sons, Baltimore, Maryland (1989,2002) and in Perbal, A Practical Guide to Molecular Cloning, John Wiley & Sons, New York (1988), and in Watson et al., Recombinant DNA, Scientific American Books, New York and in Birren et al (eds) Genome Analysis : A

Laboratory Manual Series, Vols. 1-4 Cold Spring Harbor Laboratory Press, New York (1998) and methodology as set forth in United States patents 4,666, 828; 4,683, 202; 4,801, 531 ; 5,192, 659 and 5,272, 057 and incorporated herein by reference. Polymerase chain reaction (PCR) was carried out generally as in PCR Protocols: A Guide To Methods And Applications, Academic Press, San Diego, CA (1990). In-situ (In-cell) PCR in combination with Flow Cytometry can be used for detection of cells containing specific DNA and mRNA sequences (Testoni et al, 1996, Blood 87: 3822. ) General methods in immunology : Standard methods in immunology known in the art and not specifically described are generally followed as in Stites et al. (eds), Basic and Clinical Immunology (8th Edition), Appleton & Lange, Norwalk, CT (1994) and Mishell and Shiigi (eds), Selected Methods in Cellular Immunology, W. H. Freeman and Co. , New York (1980).

Immunoassays : In general, ELISAs are the preferred immunoassays employed to assess a specimen. ELISA assays are well known to those skilled in the art. Both polyclonal and monoclonal antibodies can be used in the assays.

Where appropriate other immunoassays, such as radioimmunoassays (RIA) can be used as are known to those in the art. Available immunoassays are extensively described in the patent and scientific literature. See, for example, United States patents 3,791, 932; 3, 839, 153; 3,850, 752; 3,850, 578; 3,853, 987; 3,867, 517; 3,879, 262; 3,901, 654; 3,935, 074; 3,984, 533; 3,996, 345; 4,034, 074; 4,098, 876; 4,879, 219; 5,011, 771 and 5,281, 521 as well as Sambrook et al, Molecular Cloning : A Laboratory Manual, Cold Springs Harbor, New York, 1989 Western Blot Analysis : Western blot analysis as well as, co-immunoprecipitation employed to assess levels of expression and to demonstrate association of two proteins in Ausubel et al., Current Protocols in Molecular Biology, John Wiley and Sons, Baltimore, Maryland (1989,2002).

Antibody Production: Antibodies can be either monoclonal, polyclonal or recombinant.

Conveniently, the antibodies can be prepared against the immunogen or portion thereof for example a synthetic peptide based on the sequence, or prepared recombinantly by cloning techniques or the natural gene product and/or portions thereof can be isolated and used as the immunogen.

Immunogens can be used to produce antibodies by standard antibody production technology well known to those skilled in the art as described generally in Harlow and Lane, Antibodies: A Laboratory Manual, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, 1988 and Borrebaeck, Antibody Engineering-A Practical Guide, W. H. Freeman and Co. , 1992.

Antibody fragments can also be prepared from the antibodies and include Fab, F (ab') 2, and Fv by methods known to those skilled in the art.

For producing polyclonal antibodies a host, such as a rabbit or goat, is immunized with the immunogen or immunogen fragment, generally with an adjuvant and, if necessary, coupled to a carrier; antibodies to the immunogen are collected from the sera. Further, the polyclonal antibody can be absorbed such that it is monospecific. That is, the sera can be absorbed against related immunogens so that no cross-reactive antibodies remain in the sera rendering it monospecific.

For producing monoclonal antibodies the technique involves hyper immunization of an appropriate donor with the immunogen, generally a mouse, and isolation of splenic antibody producing cells. These cells are fused to a cell having immortality, such as a myeloma cell, to provide a fused cell hybrid, which has immortality and secretes the required antibody.

The cells are then cultured, in bulk, and the monoclonal antibodies harvested from the culture media for use.

For producing recombinant antibody (see generally Huston et al, 1991; Johnson and Bird, 1991; Mernaugh and Mernaugh, 1995), messenger RNAs from antibody producing B-lymphocytes of animals, or hybridoma are reverse-transcribed to obtain complimentary DNAs (cDNAs). Antibody cDNA, which can be full or partial length, is amplified and cloned into a phage or a plasmid. The cDNA can be a partial length of heavy and light chain cDNA, separated or connected by a linker. The antibody, or antibody fragment, is expressed using a suitable expression

system to obtain recombinant antibody. Antibody cDNA can also be obtained by screening pertinent expression libraries.

The antibody can be bound to a solid support substrate or conjugated with a detectable moiety or be both bound and conjugated as is well known in the art. (For a general discussion of conjugation of fluorescent or enzymatic moieties see Johnstone & Thorpe, Immunochemistry in Practice, Blackwell Scientific Publications, Oxford, 1982. ) The binding of antibodies to a solid support substrate is also well known in the art. (see for a general discussion Harlow & Lane Antibodies: A Laboratory Manual, Cold Spring Harbor Laboratory Publications, New York, 1988 and Borrebaeck, Antibody Engineering-A Practical Guide, W., H. Freeman and Co. , 1992) The detectable moieties contemplated with the present invention can include, but are not limited to, fluorescent, metallic, enzymatic and radioactive markers such as biotin, gold, ferritin, alkaline phosphatase, b-galactosidase, peroxidase, urease, fluorescein, rhodamine, tritium, 14C and iodination.

Recombinant Protein Purification: Marshak et al,"Strategies for Protein Purification and Characterization. A laboratory course manual."CSHL Press, 1996.

Transgenic and Knockout Methods: The present invention can provide for transgenic gene and polymorphic gene animal and cellular (cell lines) models as well as for knockout models. These models are constructed using standard methods known in the art and as set forth in United States Patents 5,487, 992, 5,464, 764,5, 387,742, 5,360, 735,5, 347,075, 5,298, 422,5, 288,846, 5,221, 778,5, 175,385, 5,175, 384,5, 175,383, 4,736, 866 as well as Burke and Olson (1991), Capecchi (1989), Davies et al. (1992), Dickinson et al.

(1993), Duff and Lincoln (1995), Huxley et al. (1991), Jakobovits et al.

(1993), Lamb et al. (1993), Pearson and Choi (1993), Rothstein (1991), Schedl et al. (1993), Strauss et al. (1993). Further, patent applications WO 94/23049, WO 93/14200, WO 94/06908, WO 94/28123 also provide information.

D-sheet breakers for amvioidoses therapy :

Cystatinn C or fragments derived from it, or peptide sequences generated based on the cystatin C sequences that bind to amyloid proteins such as Ap can be used as p-sheet breakers. These are drugs designed to specifically bind an amyloid protein and block and/or reverse the abnormal conformational change that occurs in the protein (Bieler S. , Soto, C., i- sheet breakers for Alzheimer's disease therapy. Curr Drug Targets. 2004 Aug; 5 (6): 553-8).

EXAMPLE ONE: In example one, it is demonstrated that colocalization of cystatin C, an inhibitor of cysteine proteases, with amyloid ß (Aß) in parenchymal and vascular amyloid deposits in brains of AD patients reflect cystatin C's involvement in amyloidogenesis. This is demonstrated by exhibition of colocalization of cystatin C and P amyloid precursor protein (ßÅPP) within transfected cells and show the binding of cystatin C to the Ap region within full-length ßAPP and secreted ßAPP (sßAPP), and to a GST-Aß fusion protein. Furthermore, cystatin C shows high affinity binding to both Api-42 and Api-40 in a saturable and a concentration-dependent manner. In vitro studies reveal that while cystatin C association with ßAPP does not affect A (3 secretion, its direct binding to Ap inhibits Ap fibril formation, Methods DNA constructs Full-length human wild type and variant cystatin C genomic DNAs were used for stable transfection of human embryonic kidney HEK293 cells. Human wild type and variant cystatin C cDNAs were used for transient transfection. ßAPP695 cDNA was used for transfection of mouse neuroblastoma N2a cells and ßAPP751 cDNA was used for transfection of HTEK293 cells. ßAPP deletion mutants were constructed using either PCR amplification or site-directed mutagenesis: aAPPi-65o, encodes amino acids 1-650 of ßAPP695, including the extracellular domain, the transmembrane domain and two amino acids of the cytoplasmic domain; ßAPPATM, is ßAPP695 with a deletion of sequences encoding the transmembrane

residues residues 625-648; ßAPP696-695, contains the signal sequence from position - 48 to +61 and sequences encoding the 100 carboxyl-terminal amino acids of ßAPP including the cytoplasmic domain, the transmembrane domain and A (3 ; and PAPP624-695, contains the signal sequence from position-48 to +61 and sequences encoding the 71 carboxyl-terminal amino acids of ßAPP including the cytoplasmic domain, and the transmembrane domain including Ap starting at position 29. All fragments were cloned into the eukaryotic expression vector pRK5.

Cell culture HEK293 and N2a cells were cultured in Dulbecco's modified Eagle's medium at 37°C in 5% C02 atmosphere. The media were supplemented with 10% fetal bovine serum, 100 U/ml of penicillin and 100 µg/ml streptomycin sulfate.

Transfection of cell lines The plasmids were transfected into either HEK293 or N2a culture cell lines using calcium phosphate. Stably transfected cells were selected using Geneticin (G418, GIBCO). The establishment of cell lines stably transfected with either wild type or HCHWA-I variant cystatin C genes was previously described. N2a cells were stably transfected with pAPP cDNA.

Expression of transfected genes was confirmed by immunoblot analysis of cell lysate and medium proteins.

Antibodies used Polyclonal anti-cystatin C (Axell) ; monoclonal anti-Aß1-17 (6EIO, Signet Laboratories); monoclonal anti-ßAPP66 81 (22C11, Boehringer Mannheim); polyclonal anti- (3APP65o-695 ; monoclonal antibodies against the C-terminus of Aß40 (JRF/cAß40/10) or AP42 (JRF/cA (342/26), and human Aß1-16 (JRF/ Aßtot/17).

Indirect immunofluorescence Transfected cells grown on coverslips were permeabilized and fixed in methanol at-20°C for 10 minutes. Cells were washed in phosphate buffered saline pH 7.3 (PBS), blocked with 1% bovine serum albumin in PBS for 10 minutes and incubated with primary antibody in blocking buffer for one hour at 37°C. The secondary antibodies used were either

fluorescein-isothiocyanate (FITC)-conjugated anti-mouse or anti-rabbit IgG, or Texas Red-conjugated anti-rabbit IgG (Vector Labs). The coverslips were mounted on glass slides using Vectashield mounting medium (Vector Laboratories). Incubation of live cells with antibodies to extracellular epitopes was used to demonstrate cell surface staining. Cells were incubated with primary antibodies at 4°C for one hour, washed with PBS, and permeabilized and fixed with methanol at-20°C for 10 minutes.

Following blocking, the cells were incubated with antibodies to intracellular epitopes and then with secondary antibodies as described above. In control experiments, in order to remove extracellular proteins adsorbed onto the cell surface, the cells were acid-treated prior to primary antibody incubation. For this purpose, cells were washed with PBS and incubated with 0.2 M sodium acetate, 500mM NaCI pH 4.5 for 3 minutes at 4°C. After washing with PBS, cells were labeled with primary antibody for 1 h at either 4 or 37°C. Cells were then permeabilized and fixed with methanol, blocked and incubated with antibodies to intracellular epitopes and thea with secondary antibodies as described above. Confocal laser scanning- microscopy was performed.

Immunoprecipitation analysis Media was replaced 16 hours after transient transfection, harvested 24 hours later, and spun at 4,500 x g for 10 minutes at 4°C. Cells were harvested in RIPA buffer (1% NP-40,0. 5% cholic acid, 0. 1% SDS; 150 mM NaCI, 10mM Tris-HCI, pH 8.0) with protease inhibitors (7. 5 ug/ml Apro- tinin; 5 ug/ml leupeptin ; 2 mM PMSF) and centrifuged for 5 minutes at 10,000 rpm at 4°C. Cellular and secreted proteins were immunoprecipitated with either polyclonal antibodies and Protein A Sepharose (Pharmacia Biotech) for 4 hours at 4°C or with monoclonal antibodies overnight at 4°C and with GammaBind Plus Sepharose beads (Pharmacia Biotech) for 2 hours at 4°C. The immunoprecipitated proteins were boiled in sample buffer (1% SDS, 3.3% glycerol, 1. 6% ß- mercaptoethanol and 20 mM Tris-HCI pH 6.8), separated by either 8% SDS-polyacrylamide gel electrophoresis (PAGE) or 16.5% Tris-Tricine- PAGE, electrophoretically transferred (1 hour at 400mA at 4°C) to

nitrocellulose transfer membranes (BioRad) using 10 mM 3- cyclohexylamino-1-propanesulfonic acid, adjusted to pH 11.0 containing 10% methanol, and the membranes subjected to immunoblot analysis.

Pulse/chase labelina of (3APP N2a cells stably transfected with (3APP and transiently transfected with either cystatin C or vector cDNAs were labeled 24 hours after transient transfection with 0.3 mCi/ml 35S methionine/cysteine EXPRE35S35S (DuPont NEN, Boston, MA) in methionine/cysteine free medium with 5% dialyzed serum for a pulse of 20 minutes at 37°C. Following a wash with PBS, the cells were chased in complete medium with 150 ug/ml methionine at 37°C for different periods. The media was collected and spun at 4,500 x g for 10 minutes at 4°C. The cells were harvested in PBS, lysed in 500 pi RIPA buffer with protease inhibitors and centrifuged at 4,500 x g for 10 minutes at 4°C. SDS was added to cell supernatants and media to a final concentration of 0.4%. After boiling for 4 minutes, samples were supplemented with 173 pi buffer A (760mM NaCI, 200mM Tris-HCI, 25mM EDTA, 10% Triton X- ! 00,20mM cysteine, 20mM methionine; 4mg/mi BSA; and protease inhibitors). Equal amounts of total proteins from cell lysates or equal volumes of media; based upon the relative concentration of total proteins in cell lysats, were immunoprecipitated with 6EI0 overnight at 4°C and with GammaBind Plus Sepharose (Amersham Pharmacia Biotech, Piscataway, NJ), for 2 hours at 4°C. The immunopre- cipitated proteins were washed with buffer B (150 mM NaCI, 10mM Tris- HCI, 5mM EDTA, 0. 1% TritonX-100,5 mM cysteine, 1 mg/ml BSA, and protease inhibitors) and PBS, boiled in sample buffer and separated by 8% SDS-PAGE. The gels were enhanced with Amplify (Amersham-Life Science, Buckinghamshire, England) and exposed to-X-ray films. The protein bands were scanned using Adobe Photoshop and quantified using the NIH Image program. Relative intensity of the bands was calculated as percentage of the intensity of the protein band in cell lysates at time zero of the chase. Results are expressed as means S. E. M. Data were compared between experimental groups using two-way ANOVA (GraphPad Prism). Direct quantification of incorporated radioactivity

indicated a significant positive correlation between quantification done by densitometry and direct measurements of incorporated radioactivity.

Sandwich enzvme-linked immunosorbent assay (ELISA) for detection of AR Twenty-four hours after transfection, transiently transfected cells were incubated with complete medium for 6 hours, and the media harvested as described above. Levels of human A (3 in the media were determined by sandwich ELISA as previously described.

Purification of cvstatin C from tissue culture media Wild type and variant cystatin C were isolated from media of stably transfected HEK293 cells, grown to near confluence and incubated in medium without serum for 24 hours. The conditioned media were collected and spun at 4,500 x g for 10 minutes at 4°C to remove cellular debris, and dialyzed against ddH20 in Spectra/Por membrane (MWCO 6000-8000) (Spectrum Medical Industries). Following lyophilization, the media was resuspended in 20mM NH4HCO3 pH 9.4 and applied to a DEAE Sephacel (Pharmacia) column equilibrated in the same buffer at 4°C. Under these conditions cystatin C does not bind to the column and elutes with the flow through, while most of other proteins present in the media absorb onto the column. Fractions were monitored by UV spectrophotometry at 280nm and immunoblot analysis. Fractions containing cystatin C were then pooled and aliquots boiled in sample buffer, separated on 10% Tris-Tricine-PAGE and transferred to nitrocellulose membranes. The purity of cystatin C in the samples was determined by staining the membranes with 0. 1% Coomassie blue R-250 (BioRad) in 40% methanol, 10% acetic acid. Protein concentration was estimated in solution by a colloidal gold assay according to the manufacture's protocol (Quantigold, Diversified Biotech), using urinary cystatin C (Calbiochem Biosciences, La Jolla, CA) as standard.

Amino-terminal amino acid sequence analysis was performed to confirm the purity and isolation of full-length cystatin C on a Procise 494 protein sequencer (Applied Biosystem). The resulting phenylthiohydantoin amino acid derivatives were identified using the on-line model 140C Microgradient Delivery System analyzer and a standard program (Applied Biosystems).

Analysis of the inhibitory activity of the wild type and variant cystatin C purified from tissue culture media revealed that both proteins effectively inhibited the proteolytic activity of cathepsins.

Binding assay utilizincLa glutathione S-transferase (GST) fusion protein Ap1-42 was expressed as a GST-fusion protein. The fusion protein was immobilized on a glutathione affinity matrix (Sigma) and the concentration adjusted by comparison with protein standards visualized by Coomassie stain. Fifty micrograms of fusion protein was mixed with 100 ul culture media of HEK293 cells stably transfected with either wild type or variant cystatin C for 2 hours at 4°C. After thorough washing with binding buffer (20 mM triethanolamine-HCI pH 7.5, 150 mM NaCI, 10 mM EDTA, 0.5% Triton X-100, 0, 1 % mercaptoethanol, 1 mM PMSF), fusion proteins and their bound proteins were released from the insoluble matrix by boiling in sample buffer. The proteins were separated on 16.5% Tris-Tricine-PAGE and the transfer membranes were immunoblotted with anti-cystatin C antibody.

Binding of cystatin C to Aß peptídes The dissociation constants of cystatin C for binding interaction with A (3 peptides were estimated by ELISA using immobilized either Ars140 or Api-42 peptides as described. The Ap peptides were synthesized at the W. M. Keck Facility at Yale University using N-tert-butyloxycarbonyl chemistry and purified by reverse-phase high performance liquid chromatography. Two different batches of each peptide were used in the experiments. Wild type and variant cystatin C, purified from conditioned media as described above, were compared to urinary cystatin C (Calbiochem Biosciences). Polystyrene microtiter plates (Immnunolon 2; Dynex Technology) were coated for 16 hours at 4°C with freshly dissolved Ap peptides (400 ng in 100 ul of NaHCO3 pH 9.6 per well). After blocking with 200 pi Superblock (Pierce), increasing concentrations of either wild type, variant or urinary cystatin C (0-37.5 nM) in 100 ul TBS-T (20 mM Tris- HCI, 150mM NaCI pH 7.4, containing 0. 1% Tween-20) were added to the Ap-coated wells and incubated for 3 hours at 37°C. Bound cystatin C was detected with 100 pi polyclonal anti-cystatin C antibody (1: 600) followed by

100 ul horseradish peroxidase-conjugated F (ab') 2 anti-rabbit IgG (1: 4000, Amersham) and developed using 100 pi 3,3', 5, 5'-tetramethyl-benzidine as substrate; Absorbency was read at 450 nm after stopping the reaction with 100 ul 2.5N sulfuric acid. Non-linear regression analysis, estimation of dissociation constants and comparison of protein binding data were assessed for statistical significance with GraphPad Prism software (GraphPad, San Diego, CA, USA). P values were calculated by one-way ANOVA of three independent repeated measures of duplicate samples.

For competition experiments, microtiter plates were coated with either Api- 40 or Api-42 peptides. Ten nanomolar urinary cystatin C was added together with various concentrations of 6E10-and bound cystatin C was detected as described above.

Electron microscopical analvsis of fibril formation Various amounts of urinary cystatin C (0.01-3. 5 ug) (Calbiochem Biosciences) were incubated with API-42 (1 ug) for 3 days or Api-40 (2-4 ug) for 10-14 days at 37°C in 10 pi of 20 mM Tris-HCI pH 7.0, 150 mM NaCI. After incubation, the suspension was placed on 400 mesh nickel grids coated with formvar/carbon (Electron Microscopy Sciences, Fort Washington, PA). The grids were stained for 60 seconds with 1% uranyl acetate and visualized on a Zeiss EM 10 electron microscope at 80kV.

Results : Subcellular distribution of cvstatin C and ßAPP Experiments for the intracellular localization of cystatin C and ßAPP within cultured cells were carried out using indirect immunofluorescence and visualization with a confocal microscope. Human embryonic kidney HEK293 cells stably transfected with cystatin C were transiently transfected with ßAPP cDNA. Staining with anti-ßAPP 22C11 antibody (Figure 1A) or with anti-cystatin C antibody (Figure 1B) revealed cytoplasmic punctate staining. Significant colocalization of both proteins is seen in yellow in the superimposed figure (Figure 1 C).

Staining of mouse neuroblastoma N2a cells transiently

cotransfected with (3APP and cystatin C cDNAs with 22C11 antibody revealed cytoplasmic and cell surface localization of RAPP (Figure 1 D and G). Cystatin C distribution in these cells was primarily intracellular (Figure 1 E and H). However, staining of cystatin C was also observed on the cell surface and nerve terminals, in areas resembling growth cones (Figure 1 E). Colocalization of cystatin C and (3APP is observed in the superimposed figures (Figure 1 F and 1). Wild type and variant cystatin C showed the same staining pattern. No staining was observed when the anti-cystatin C antibody was used for cell surface staining of non- transfected cells.

Cell surface proteins were detected by incubating live cells with antibodies prior to permeabilization of the cells. An antibody against the amino-terminus of ßAPP (22C11) revealed cell surface (3APP (Figure 2A, D, and G). Staining of live cells with anti-cystatin C antibody confirmed the cell surface localization of cystatin C (Figure 2B, E, and H). An attempt to remove cystatin C from the cell surface by washing the cells with sodium acetate pH 4.5 resulted in a reduction of the level of cell surface staining with anti-cystatin C antibody, suggesting that the observed cell surface staining can represent adsorbence of secreted cystatin C onto the cells.

Cystatin C cell surface staining was stronger when cells were incubated with the antibody at 37°C (Figure 2E) compared to cells incubated at 4°C (Figure 2B and H). Reduced level of cystatin C at the plasma membrane can reflect reduced secretion of the protein at lower temperature.

Coimmunoprecipitation of cystatin C with DA The interaction of cystatin C with (3APP was examined in HEK293 cells stably expressing either wild type or variant cystatin C genes, and transiently transfected with either wild type (3APP or vector cDNAs.

Expression of (3APP is demonstrated by immunoblot analysis of cell lysate proteins with 22C11 (Figure 3, upper panels). Binding was demonstrated by immunoprecipitation of cell lysate or media proteins with anti-cystatin C antibody followed by separation by SDS-PAGE and immunoblot analysis with 22C11 (Figure 3, lower panels). The data indicates binding between cystatin C and cell associated full-length as well as s) 3APP. To rule out the

possibility that the association of cystatin C with ßAPP is not specific, it was confirmed that the adapter proteins, Grb2 and Shc, do not bind ßAPP. The association between cystatin C and ßAPP was demonstrated also in AD brain homogenates by immunoprecipitation with anti-AR antibody followed by separation by SDS-PAGE and immunoblot analysis with anti-cystatin C antibody.

In order to study the cystatin C binding site within ßAPP, deletion mutants of ßAPP were used. Expression of the ßAPP constructs in HEK293 cells is demonstrated by immunoblot analysis of cell lysate proteins with anti-ßAPP antibodies (Figure 4, upper panels). Binding is demonstrated by immunoprecipitation of cell lysate proteins with anti- cystatin C antibody followed by immunoblot analysis with anti-ßAPP antibodies (Figure 4, lower panels). An anti-cystatin C antibody coimmunoprecipitated the deletion constructs lacking the carboxyl-terminus (ßAPP1 650) or transmembrane domains (ßAPP-D-TM). ßAPP595695 con- taining the carboxyl-terminal 100 amino acid, including Ap, also immunoprecipitated with the anti-cystatin C antibody. However, the pAPPe24-695 containing the carboxyl-terminal 71 amino acid of ßAPP, but lacking the extracellular domain of Ap, did not coimmunoprecipitate with the anti-cystatin C antibody. These results, along with the finding that cystatin C binds to sßAPP, demonstrate that the cystatin C binding domain resides within the amino-terminus of the Ap region.

Effect of ßAPP association with cystatin C on ßAPP processing In order to examine the effect of cystatin C expression on ßAPP processing, N2a stably transfected with ßAPP were labeled with 35S methionine/cysteine for 20 minutes and chased for different time periods.

ßAPP species were immunoprecipitated with 6E10 from cell lysates and media proteins, separated by polyacrylamide gel electrophoresis and the relative intensity of each band was calculated as a percent of the intensity of the protein band in cell lysates at time zero of the chase. Transient transfection with cystatin C revealed that cystatin C association with ßAPP results in higher levels of NAPPA secretion compared to cells transiently transfected with vector (Figure 5).

In addition, Ap secretion by N2a cells transiently transfected with both cystatin C and (3APP was examined. ELISA analysis of secreted Api- 40 and Api. 42 revealed similar levels of both Ap peptides, compared to cells cotransfected with LAPP and vector (Figure 6). Thus, cystatin C association with (3APP does not affect Ap secretion.

Cystain C bindinatoGST-Aj fusion protein In vitro binding assays were carried out using the GST-Aß142 fusion protein previously described. Media of HEK293 cells stably transfected with either wild type or variant cystatin C genes served as the source of cystatin C. Fusion proteins were immobilized on glutathione affinity matrix and mixed with cell culture media. Immunoblot analysis with anti-cystatin C antibody revealed binding of wild type cystatin C or the variant protein to GST-Api-42 (Figure 7). No binding was observed using either media of cells transfected with vector (Figure 7) or when GST protein without the Ap sequence was used.

The Association of cystatin C and AI3 To further examine the association between cystatin C and Ap, cystatin C was purified from media conditioned by HEK293 cells stably transfected with either wild type or variant cystatin C genes. ELISA was then performed by coating microtiter plates with freshly dissolved either Api-40 or Api-42. After blocking, different concentrations of purified cystatin C were added. Bound cystatin C was detected with anti-cystatin C antibody. Cystatin C interacted with Ap at physiologic pH and temperature and in a concentration-dependent manner. A specific saturable and high affinity binding was observed between wild type, variant or urinary cystatin C and either A (31-40 or Api-42. (Figure 8). The binding curve fit to a rectangular hyperbola corresponding to a single binding site with dissociation constant Kd values in the low nanomolar range. The monoclonal antibody 6E10, which binds to residues 1-17 of A (3, abolished cystatin C binding to Ap-coated plates (Figure 9). Low concentrations of the antibody (5nM) were enough to block the binding. An unrelated monoclonal antibody used as a control had no effect on cystatin C binding to Ap. These results support the findings that the cystatin C binding site

within Ap is within the amino-terminal domain of the peptide.

Electron microscopical analysis of fibril formation Incubation of either Api-40 or Api-42 in conditions described in the Experimental Procedures resulted in formation of fibrils. Incubation of cystatin C with either Api-40 or Api-42 inhibited fibril formation in a concentration-dependent manner. Incubation of 1 ug of the highly fibrilogenic Api-42 peptide with various amounts of cystatin C for three days demonstrated fibril formation in the presence of low levels of cystatin C (0-0. 1 ug), occasional fibrils in the presence of 0. 5 ug cystatin C and the absence of fibrils when incubated with higher amounts of cystatin C (2 ug) (Figure 11). Similarly, incubation of 2 or 4 ug A (3i-4o with cystatin C for 10 days revealed formation of fibrils in the presence of 0-0. 1 ug cystatin C and their absence with 0.5-2 lug cystatin C (Figure 11). Incubation of cystatin C alone often results in the formation of amorphous aggregates, which were also seen in the A (3 co-incubations (Figure 10). These results suggest that cystatin C reduces the speed of auto-polymerization of Ap as a result of substoichiometrical direct binding and competition for Ap.

Discussion: Immunohistochemical studies of patients with AD and cerebral amyloid angiopathy due to Ap deposition have demonstrated dual labeling of Ap and cystatin C. Cystatin C also co-localizes with A (3 amyloid deposits in the brain of non-demented aged individuals, aged rhesus and squirrel monkeys, and transgenic mice overexpressing human ßAPP.

Furthermore, it has been previously shown by immunohistochemical analysis using anti-cystatin C antibody strong punctate immunoreactivity within the cytoplasm and cell processes of pyramidal neurons mainly in layers III and IV of the cortex of aged individuals and AD patients. Using an end-specific antibody to the carboxyl-terminus of A (342, intracellular immnunoreactivity in the same neuronal sub-population was observed.

Our data suggest that A (342 accumulates in a specific population of pyramidal neurons in the brain, the same cell type in which cystatin C is highly expressed. Pyramidal neurons in layers III and V in the cortex of AD patients have also displayed a quantitative increase in aspartic protease

cathepsin D immunoreactivity. Deng et al. has demonstrated that neuronal staining of cystatin C in AD brains was primarily limited to pyramidal neurons in cortical layers III and V. The regional distribution of cystatin C neuronal immunostaining duplicated the pattern of neuronal susceptibility in AD brains: the strongest staining was found in the entorhinal cortex, in the hippocampus, and in the temporal cortex; fewer pyramidal neurons were stained in the frontal, parietal, and occipital lobes. Immunostaining of cystatin C within neurons showed a punctate distribution, which co- localized with the endosomal/lysosomal protease cathepsin B.

Upregulation of cathepsin synthesis in AD neurons and accumulation of hydrolase-laden lysosomes indicate an early activation of the endosomal/lysosomal system in vulnerable neuronal populations, possibly reflecting early regenerative or repair processes. These neuropathological observations suggest an association between cystatin C and AD.

It has been determined that there is a cellular and biochemical association of cystatin C with A [3 and cystatin C has an effect on (3APP processing and amyloid fibril formation. Cell culture studies demonstrated that cystatin C and (3APP significantly colocalize, both within the cell and at the cell surface. This cell surface localization of cystatin C is unexpected given the primary structure of cystatin C and that it has been previously demonstrated that the full-length protein is secreted by both HEK293 and N2a cells. This suggests that cell surface cystatin C staining can represent binding of secreted cystatin C to another molecule (s) localized at the plasma membrane. Similar observations using immunofluorescent confocal microscopy to localize cystatin C within an embryonic liver cell line and an invasive hepatoma cell line showed that cystatin C immunolabeling was not only cytoplasmic, but also present on the cell surface. Labeling of cystatin C was also found on the extracellular plasma membrane of adult rat hippocampus-derived neural progenitor cells undergoing cell division, and it was shown that cystatin C binds to the plasma membrane of these cells.

Demonstration of binding of cystatin C to full-length PAPP and to sßAPPa proves that (3APP can be one cell surface binding protein of cystatin C.

Vattemi et al. have recently studied the expression and localization of

cystatin C in muscle biopsies of patients with sporadic inclusion-body myositis (s-IBM) because the phenotype of muscle cells in these patients has several similarities with the phenotype of AD brain, including abnormal accumulation of A (3 deposits. Cystatin C-immunoreactivity colocalized with the Aß-immunoreactive inclusions in the vacuolated muscle fibers, mostly in nonvacuolated regions of their cytoplasm. Cystatin C co- immunoprecipitated with ßAPP both in s-IBM muscle and in RAPP- overexpressing cultured normal human muscle fibers.

Deletion mutants of (3APP localized the cystatin C binding domain to the extracellular region of A (3. Moreover, complete inhibition of the binding by competition with the anti-Api-17 antibody 6E10, indicated direct involvement of the amino-terminus of A (3 in cystatin C binding. Cystatin C binds not only to Ap sequences within (3APP, but also to the peptide itself.

Cystatin C binds A [3 with a dissociation constant in the nanomolar range, similar to other well studied interactions of A (3 with binding proteins such as apolipoprotein E and clusterin.

Most importantly, our data demonstrate that in vitro binding of cystatin C to Ap inhibits amyloid-fibril formation. The occurrence of cystatin C in A (3 amyloid deposits can result from cystatin C binding to the precursor protein prior to Ap generation, or alternatively, cystatin C can bind to Ap prior to its secretion, or following Ap deposition in the brain. a1- antichymotrypsin and a2-macroglobulin are two other protease inhibitors that have been shown to be present in senile plaques in AD. Both inhibitors bind Ap and can inhibit fibril formation. In vitro incubation of either Api-40 or A PI-42 resulted in formation of fibrils. However, samples containing either peptide together with cystatin C caused the disappearance of the fibrils and appearance of amorphous aggregates, oc- casionally seen also in samples containing cystatin C alone. This effect was dependent on the concentration of cystatin C relative to the concentration of the Ap peptide. Substoichiometrical amounts of cystatin C inhibit Ap fibril formation.

EXAMPLE TWO :

As demonstrated in Example Two, cystatin C, colocalizes with Ap in parenchymal and vascular amyloid deposits in brains of AD patients, which proves cystatin C has a role in AD. Cystatin C also colocalizes with ßAPP in transfected cultured cells. In vitro analysis of the association between the two proteins revealed that binding of cystatin C to full-length LAPP does not affect the level of Ap secretion. In Example two, the effect of in vivo overexpression of cystatin C on the levels of endogenous brain A (3 was determined. Lines of transgenic mice were generated that expressed either wild type human cystatin C or the Leu68Gln variant that forms amyloid deposits in the cerebral vessels of Icelandic patients with hereditary cerebral hemorrhage, under control sequences of the human cystatin C gene. Western blot analysis of brain homogenates was used to select lines of mice expressing various levels of the transgene. Analysis of A (340 and A (342 concentrations in the brain showed no difference between transgenic mice and their non-transgenic littermates. Thus, in vivo overexpression of human cystatin C does not affect Ap levels in mice that do not deposit A (3.

Materials and Methods: Generation of Cystatin C Transaenic Mice Transgenic mice were generated using either human wild type or the Leu68Gln variant cystatin C genes (CysC-W and CysC-V, respectively). Vector sequences were removed by digestion with Hindlil.

The 8.9 kb full-length human cystatin C genes were injected into donor outbred Swiss-Webster single cell embryos. Swiss-Webster carriers of the transgene were crossed with C57BL/6 wild type mice.

Polymerase Chain Reaction (PCR) Analysis of Tail DNA Transgenic mice were identified by amplification of a 126-bp DNA fragment unique to the human cystatin C sequence from DNA isolated from tails, using forward 5'-ATGGACGCCAGCGTGGAGGA-3'and reverse 5'-CTGCTTGCGGGCGCGCAC-3'primers.

Western Blot Analysis of Mouse Brain Homoqenates Mouse brains were homogenized in 150 mM NaCI, 1% Nonidet P-

40, 1% sodium deoxycholate, 0. 1% SDS, 10mM sodium phosphate (pH 7.2), 10 uM leupeptin, 10 uM aprotinin, and 2 mM phenylmethylsulfonyl fluoride (PMSF). The homogenates were centrifuged at 10, 000g for 15 minutes, and the supernatant used. Identical amounts of total brain protein were applied to each lane of 10% SDS-polyacrylamide gel, confirmed by Western blot analysis with anti-ß-tubulin antibody (1: 600; BioGenex Laboratories) and Ponceau Red staining of the membranes. A polyclonal anti-cystatin C antibody (1: 600; Axell) was used to identify cystatin C transgene expression.

Sandwich Enzyme-Linked Immunosorbent Assay (ELISA) for Detection of Ap Frozen mouse brains were homogenized in sucrose buffer (250 mM sucrose, 20 mM Tris (pH 7.4), 1mM EDTA, 1mM EGTA, 1mM PMSF, 10 uiv) ieupeptin, 10 uM antipain HCI, and 10 uM pepstatin A), followed by treatment with 0.4% diethylamine, 100 mM NaCl, centrifugation at 135, 000g, and neutralization with Tris-HCI at pH 6.8. Levels of endoge- nous mouse brain Ap were determined by sandwich ELISA as described previously using monoclonal antibodies against the carboxyl terminus of Aß40 (JRF/cAß40/10) or Aß42 (JRF/cAß42/26), and human Api-is (JRF/rA (31-15/2).

Results and Discussion Generation of Cystatin C Transgenic Mice Transgenic mice were generated expressing either wild type or the Leu68Gln variant cystatin C genes (CysC-W and CysC-V, respectively).

The full-length human cystatin C gene, within an 8.9-kb Hindill fragment, was utilized. It contains the three exons of the gene, the two introns, and the 5'-and 3'-untranslated regions. The constructs were expressed systemically under control sequences of the human gene. Transgenic mice have been identified by amplification of a DNA fragment of 126 bp unique to the human sequence from genomic DNA isolated from tails. The primers used do not yield a PCR product from DNA of non-transgenic mice (Fig. 12). All founders transmitted the transgene.

Selection of Cystatin C Transgenic Mouse Lines

Western blot analysis of brain homogenates was used to determine the level of transgene-derived cystatin C protein expression. Figure 13 represents a typical Western blot, using an anti-cystatin C antibody. Lines of mice expressing various levels of human wild type or variant cystatin C in the brain underwent further study. Swiss-Webster carriers of the transgene were crossed with C57BL76 wild type mice. The fifth generation of crossed mice was tested for cystatin C expression in the brain. Western blot analysis of brain homogenates revealed that all of the lines preserved the levels of cystatin C over-expression observed in the founders.

Western blot analysis of mouse brain homogenates showed that mouse cystatin C migrated at about 14 kDa (Figure 13). A minor band at about 20 kDa was also observed. As an N-glycosylation consensus sequence is present in mouse cystatin C, this band can represent glycosylated cystatin C similar to rat cystatin C. Rat cystatin C is a 13 to 14 kDa basic protein containing unique consensus sites for N-and O- glycosylation. The existence of a glycosylated form of cystatin C has been reported in rat seminal vesicles, and this glycosylated form has been purified from conditioned medium of rat neural stem cell cultures. Over- expression of human cystatin C does not correlate with an increase in the 20-kDa band (Figure 13), indicating that the glycosylated band originates from mouse cystatin C. Furthermore, human cystatin C does not have an N-glycosylation consensus sequence, suggesting that human cystatin C is not glycosylated in these transgenic mouse lines.

Characterization of Cystatin C Transqenic Mice Studies of cystatin C transgenic mice were undertaken to elucidate the role of increased expression of this protease inhibitor in vivo and in a variety of human disorders. In addition to the wild type human gene, cystatin C gene containing the mutation found in HCHWA-I patients was used to create a transgenic model of cerebral amyloid angiopathy. The single amino acid substitution in variant cystatin C changes the biology of the protein, leading to amyloid fibril formation and early deposition in brain vessel walls.

Similar to C57BL/6J homozygous for a null allele of the cystatin C

gene, the cystatin C transgenic mice are fertile and their appearance is indistinguishable from their non-transgenic littermates. They showed no gross pathological or histopathological abnormalities up to six months of age. Although cystatin C null mice are reported to be slightly hypoactive, no obvious behavioral differences were observed in cystatin C transgenic mice compared to non-transgenic littermates.

The neuropathological and biochemical examinations of a colony of aging mice including cystatin C transgenic mice and their non-transgenic siblings enables the in vivo analysis of cystatin C amyloidogenesis and its role in stroke.

Analysis of Endogenous Brain Ad Levels The levels of endogenous murine A [340 and Ap42 in brain homogenates were determined by ELISA. Brain homogenates of transgenic mice belonging to the CysC-V (M11) mouse lines were analyzed to obtain the data presented in Figure 14. Cystatin C transgene expression in the brains of mice belonging to this line was fivefold higher than mouse endogenous cystatin C levels. Similar levels of both Ap peptides were found in the brains of cystatin C transgenic mice compared to non- transgenic littermate controls (Fig. 14). Thus, overexpression of cystatin C in mice does not affect brain levels of Ap.

Growing evidence suggests that cystatin C has a role in AD. First, immunohistochemical studies have revealed the colocalization of cystatin C with Ap, predominantly in amyloid-laden vascular walls, but also in parenchymal amyloid plaques in the brains of patients with AD and cerebral amyloid angiopathy, non-demented aged individuals, aged rhesus and squirrel monkeys, and transgenic mice over-expressing human (3APP.

Second, immunohistochemical analysis using an anti-cystatin C antibody has shown strong punctate immunoreactivity within the cytoplasm and cell processes of pyramidal neurons, mainly in layers III and IV of the cortex of aged individuals and AD patients. Using an antibody specific to the carboxyl terminus of Aß42, intracellular immunoreactivity was observed in

the same neuronal subpopulation, suggesting that A (342 accumulates in a specific population of pyramidal neurons in the brain, the same cell type in which cystatin C is highly expressed. Third, colocalization of cystatin C with (3APP has been demonstrated in transfected human embryonic kidney HEK293 cells, mouse neuroblastoma N2a cells, and in muscle cells of patients with sporadic inclusion-body myositis (s-IBM). Fourth, genetic data have linked cystatin C gene polymorphisms with late-onset AD, although some studies were unable to replicate these findings. Finally, high-affinity binding of cystatin C to A (3 has been recently demonstrated, which was found to inhibit Ap fibril formation.

In coimmunoprecipitation experiments, it was demonstrated that binding of cystatin C to full-length ßAPP and to secreted ßAPPa occurs.

The cystatin C binding domain within (3APP was localized to the extra- cellular region of A (3. This binding location seems to protect (3APP from p- secretase processing, resulting in an increase in the non-amyloidogenic a- secretase cleavage, with no effect on the y-secretase cleavage site.

Accordingly, coexpression of cystatin C and ßAPP in neuroblastoma cells resulted in increased secretion of ßAPPa, whereas production of both A (340 and Ap42 remained unchanged. The data presented here demonstrates in vivo that overexpression of cystatin C does not affect the levels of endogenous murine A [3 in the brain.

EXAMPLE THREE: In Example three, data was generated supporting the finding that binding of cystatin C (CysC) to Ap inhibits Ap fibril formation in vitro and in vivo. Analysis of the association of CysC and Ap by ELISA demonstrated that CysC interacts with both Ap40 and Ars42 in a concentration dependent manner at physiologic pH and temperature. A specific, saturable and high affinity binding between CysC and Ap was observed. EM analysis of fibril formation revealed that incubation of CysC with either Ap40 or Ap42 inhibits Ap fibril formation in a concentration dependent manner [Sastre et al ; paper in appendix]. Litters of APP23 transgenic mice crossbred with CysC-V transgenic mice containing all four genotype combinations were

sacrificed at 9-12 months of age. Brain sections immunostained with 6E10, anti-Ap40 and anti-Ap42 antibodies or stained with thioflavin S were quantified. Two to three sections per staining, per brain were quantified.

The amyloid load values were compared between genotype, gender, and age of the mouse using Microsoft Excel Student's t-test. Preliminary studies demonstrate significant decrease in plaque load in the brains of double positive mice for the CysC and ßAPP genes compared with mice singly positive for the ßAPP gene (Figure 15 and 16).

Confirmation of this in vivo data was obtained by ELISA analysis of insoluble human Amino and Api-42, indicative of deposited amyloid. We used mice overexpressing ßAPP, called APP23 crossed with mice overexpressing human wild type or mutated CysC. Because female APP23 mice deposit much higher levels of Ap compared to males, the calculation were made separately for males and females. The data reveal decreased deposition of API-40 and Api-42 both in females and males in APP23+/CC+ mice compared to APP23+/CC-mice (Figure 17).

EXAMPLE FOUR: In example four, it was demonstrated that multiple human conditions associated with an increased risk of stroke have high levels of the cysteine protease inhibitor cystatin C in the plasma. Transgenic mice expressing human cystatin C under control sequences of the human cystatin C gene were generated which resulted in systemic overexpression of the transgene. Neuropathological examination revealed mice with cerebral or subarachnoid hemorrhages. Conversely, no hemorrhages were observed in their non-transgenic siblings. The data demonstrates a direct relationship between elevated brain and/or blood levels of cystatin C and hemorrhagic strokes, providing a murine model of spontaneous cerebral hemorrhage and demonstrating a target for therapeutic prevention of stroke.

A L68Q variant cystatin C is the major constituent of amyloid deposited in the brain of patients with hereditary cerebral hemorrhage with amyloidosis, Icelandic type (HCHWA-I). Amyloid deposition in cerebral

arteries and arterioles leads to recurrent hemorrhagic strokes causing serious brain damage and eventually fatal stroke before the age of 40 years.

Transgenic mice expressing either wild type human cystatin C (CysC-W) or the L68Q variant (CysC-V) under control sequences of the human cystatin C gene were generated. The mouse lines expressed various levels of the transgene, and consistently showed a higher cystatin C concentration in plasma than in brain. Among a colony of transgenic mice and non-transgenic siblings set up for aging, transgenic mice began dying spontaneously at around six months of age. Gross examination of the brain revealed subarachnoid and/or large intraparenchymal hemorrhages only in transgenic mice (Figure 18a and 18b). Histological analysis of brain sections stained with hematoxylin-eosin or Perls'to visualize ferric iron in hemosiderin showed that transgenic mice with large hemorrhages frequently also had intracerebral micro-hemorrhages of various sizes and stages of evolution (Fig. 18c-18e). The older lesions were distinguished by the presence of Perls'positive material (Fig. 18c).

Occasionally, ventricular subarachnoid hemorrhage was associated with infiltration by lymphocytes and mononuclear cells (Fig. 18f). Small hemorrhages and hemosiderin deposits in perivascular spaces or in the neuropil also were present in overtly ill aged transgenic mice. Conversely, no macro-or micro-hemorrhages were found in any non-transgenic littermates.

Cerebral hemorrhages were observed in all transgenic lines between 6 and 22 months of age, with no differences between animals expressing wild type versus variant cystatin C, or between males and females. Analysis of spontaneously dead or ailing transgenic mice with the highest level of cystatin C transgene expression in the brain (Cys-V-M11), revealed twelve animals with hemorrhages (6,8, 12,14, 15,16, 16,16, 16, 17,19 and 21 months of age) out of 86 mice. Among a smaller colony of mice belonging to line Cys-V-F6, eight mice had hemorrhages (12,12, 13, 13,14, 15,18, and 18 months of age) out of 38 dead or ailing mice of the

same age range. Preliminary results with recently generated wild type lines (Cys-W) revealed two mice with cerebral hemorrhages out of 6 that spontaneously died at ages 8 and 16 months. None of the aging non- transgenic siblings had hemorrhages (36 of line Cys-V-M11, 22 of Cys-V- F6, and 6 of Cys-W lines). It should be noted that these figures could represent underestimates because animals found several hours after death showed too much attrition for reliable scoring.

To investigate whether the hemorrhages were due to vascular amyloid, brain sections were stained with amyloid-binding dyes (i. e. , Congo red and thioflavine S) or analyzed by electron microscopy. No amyloid fibrils were detected in any of the transgenic mice, with or without bleeding.

This data indicates that overexpression of cystatin C contributes to rupture of cerebral vessels in the absence of amyloid formation.

High systemic or local concentrations of cystatin C have been found in several human diseases, including diabetic nephropathy, hypertension, coronary heart disease and obesity, all conditions that are risk factors for intracerebral hemorrhage. Some subjects with severe congophilic angiopathy due to AD deposition develop cerebral hemorrhage. Cystatin C co-localizes with AD in amyloid-laden vessels, and intense cystatin C immunoreactivity is known to be associated with higher risk for cerebral hemorrhages. The relationship between elevated circulatory cystatin C concentration and the risk for hemorrhage is supported by our cystatin C transgenic mouse results, suggesting a novel approach for prevention of stroke in patients with high serum or local levels of this protein.

Throughout this application, various publications, including United States patents, are referenced by author and year and patents by number.

Full citations for the publications are listed below. The disclosures of these publications and patents in their entireties are hereby incorporated by reference into this application in order to more fully describe the state of the art to which this invention pertains. The invention has been described in an illustrative manner, and it is to be understood that the terminology

which has been used is intended to be in the nature of words of description rather than of limitation.

Obviously, many modifications and variations of the present invention are possible in light of the above teachings. It is, therefore, to be understood that within the scope of the described invention, the invention can be practiced otherwise than as specifically described.