WO2005075685A1 - Genes associated with canine osteoarthritis and related methods and compositions - Google Patents

Abstract

Described herein is a combination containing polynucleotide molecules that are differentially expressed in osteoarthritis. Also described are methods that may be used for diagnosis and prognosis of osteoarthritis, as well as methods that may be used to screen test substances for effectiveness in treatment modalities for osteoarthritis. Also described are devices and kits that may be used with the described methods.

Description

GENES ASSOCIATED WITH CANINE OSTEOARTHRITIS AND RELATED METHODS AND COMPOSITIONS

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application claims benefit of U.S. Application No. 60/541 ,346, filed February 2, 2004, the disclosure of which is hereby incorporated by reference in its entirety.

FIELD OF THE INVENTION [0002] This invention relates to the field of degenerative joint diseases, such as osteoarthritis. More particularly, the invention relates to novel compositions, devices and methods based on unique profiles of gene expression associated with osteoarthritis.

BACKGROUND OF THE INVENTION [0003] Osteoarthritis (OA), also commonly referred to as degenerative joint disease, is recognized in humans and all veterinary species (Richardson et al., (1997) Vet. Clin. North Am. 27:883-911). OA is a prevalent and debilitating disease in canines and is often associated with hip dysplasia (Martinez, S. (1997) Osteoarthritis, Net. Clinics of Ν. Am.: Small Animal Practice 27 (4):735-758.). There is a high degree of similarity between canine and human osteoarthritis, thus making it an excellent animal model for the study of human osteoarthritis. While causative factors remain largely unknown, the disease is characterized by the imbalance of cartilage matrix degradation outweighing cartilage matrix synthesis. Chondrocyte apoptosis and inflammation may also be associated with the disease (Pelletier, J., et al. (2001) Arthritis & Rheumatism 44 (6): 1237-1247; Lotz, M. (1999) Osteoarthritis and Cartilage 7: 389-391). [0004] The disease is typically slow in progression and characterized by degeneration of articular cartilage with a loss of both proteoglycan and collagen and by proliferation of new bone. In addition, an inflammatory response can occur within the synovial membrane. Canine osteoarthritis can arise as a secondary condition resulting, in particular, from hip displasia or from osteochondritis dissecans (Martinez, supra). Acquired conditions involving traumatic events can also lead to osteoarthritis in the dog (Martinez et al., Vet. Clin. North Am. 27:759-775, 1997). Treatment modalities for osteoarthritis can include the administration of anti- inflammatory drugs as well as the manipulation of dietary fatty acids (Richardson et al., supra). [0005] Diagnosis of canine osteoarthritis is typically based upon symptomatology. Dogs having osteoarthritis show a lameness which may have a gradual onset but can flare up acutely after exercise. The lameness is exacerbated by rest but decreases after a few minutes of activity. Cold damp conditions, obesity and prolonged exercise often worsen signs of lameness (Pederson et al, in Textbook of Veterinary Internal Medicine, 5th Ed., Ettinger et al., ed., W.B. Saunders and Co., Philadelphia, 2000, pp. 1862-1886). [0006] With the emergence of the genomic sciences, it has become apparent that not only is the regulation of gene expression intimately involved in normal homeostasis, alterations in the differential expression of genes is one aspect in the development of diseases. As a result, the evaluation of gene expression patterns in disease has become increasingly recognized as being crucial to the understanding of disease processes at the molecular level. (Going et al., European J. Cancer 35:1895-1904, 1999; Wang et al., Cardiovasc. Res. 35:414-421). A number of approaches have emerged for studying comparative gene expression and the current emphasis has been on high throughput analysis methods, (for review see Caralli et al, J. Cell. Biochem. Suppl. 30/32:286-296, 1998; Kozian et al., Trends Biotechnol 17:13-1 , 1999). Recent methods developed for high throughput analysis of differential gene expression include, for example, EST sequencing (Adams et al., Science 252:1651-1656, 1991; Adams et al., Nature 377:3-16, 1995), microarray hybridization (Schena et al., Science 270:461-410, 1995), and differential display (Liang et al., Science 257:967-970, 1992; Welsh et al., Nucleic Acids Res. 20:4965-4910, 1992). [0007] Gene expression in osteoarthritis, and particularly in canine osteoarthritis, has not been comprehensively studied. Accordingly, a need exists to identify nucleic acid sequences and their encoded proteins which are differentially expressed in osteoarthritis. This information would be useful to diagnose the osteoarthritic disease state, or pre-disposition to the disease, in a subject, as well as to identify substances useful in the treatment or prevention of osteoarthritis.

SUMMARY OF THE INVENTION [0008] In accordance with an aspect of the present invention, a number of polynucleotides comprising at least a fragment of a gene have been identified as being differentially expressed in osteoarthritic or pre-osteoarthritic subjects, compared to expression in subjects which are not osteoarthritic or pre-osteoarthritic. [0009] In accordance with an aspect of the present invention, differentially expressed genes, gene fragments, and encoded gene products, as well as the expression patterns associated with the group of genes, are used to advantage in a number of methods for the detection of changes in gene expression associated with osteoarthritis, particularly canine osteoarthritis. Additional aspects of the invention relate to methods for the identification of agents useful in treating and/or preventing osteoarthritis. [0010] In accordance with additional aspects of the present invention, compositions, devices and test kits are provided to facilitate the practice of methods provided according to certain embodiments of the invention. [0011] Other features and advantages of the present invention will be understood by reference to the detailed description and the examples that follow.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 shows representative gels used in differential display analysis of canine osteoarthritis. A. Differential display of osteoarthritic vs. normal transcripts loaded in duplicate prior to band excision (D=osteoarthritic (Diseased), N=Normal). B. The same gel after band excision. [0013] Figure 2 shows quantitative PCR analysis (qPCR) for selected OA-associated transcripts in canine cartilage. RNA expression is shown in arbitrary units. (OA ANG = average expression for osteoarthritic cartilage; C ANG = average expression in normal control).

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS Definitions: [0014] The following definitions are provided to facilitate an understanding of the present invention: [0015] "Nucleic acid" or a "nucleic acid molecule" as used herein refers to any DNA or RNA molecule, either single or double stranded and, if single stranded, the molecule of its complementary sequence in either linear or circular form. In discussing nucleic acid molecules, a sequence or structure of a particular nucleic acid molecule may be described herein according to the normal convention of providing the sequence in the 5' to 3' direction. With reference to nucleic acids according to aspects of the invention, the term "isolated nucleic acid" is sometimes used. This term, when applied to DNA, refers to a DNA molecule that is separated from sequences with which it is immediately contiguous in the naturally occurring genome of the organism in which it originated. For example, an "isolated nucleic acid" may comprise a DNA molecule inserted into a vector, such as a plasmid or virus vector, or integrated into the genomic DNA of a prokaryotic or eukaryotic cell or host organism. [0016] When applied to RNA, the term "isolated nucleic acid" refers primarily to an RNA molecule encoded by an isolated DNA molecule as defined above. Alternatively, the term may refer to an RNA molecule that has been sufficiently separated from other nucleic acids with which it would be associated in its natural state (i.e., in cells or tissues). An isolated nucleic acid (either DNA or RNA) may further represent a molecule produced directly by biological or synthetic means and separated from other components present during its production. [0017] The terms "percent similarity", "percent identity" and "percent homology" when referring to a particular sequence are used as set forth in the University of Wisconsin GCG software program. [0018] A "polynucleotide," "polynucleotide molecule" or "polynucleotide sequence" refers to a chain of nucleotides. It may refer to a DNA or RNA molecule, either single or double stranded and, if single stranded, the molecule of its complementary sequence in either linear or circular form. Preferably, the chain has from about 50 to 10,000 nucleotides, more preferably from about 150 to 3,500 nucleotides. In some instances, the sequences will be fully complementary (no mismatches) when aligned. In other instances, there may be up to about a 30% mismatch in the sequences. [0019] The term "oligonucleotide," as used herein refers to sequences, primers and probes of the present invention, and is defined as a nucleic acid molecule comprised of two or more ribo or deoxyribonucleotides, preferably more than three. The exact size of the oligonucleotide will depend on various factors and on the particular application and use of the oligonucleotide. [0020] A "fragment" refers to a nucleic acid sequence that is preferably at least about 10 nucleic acids in length, more preferably about 40 nucleic acids, and most preferably about 100 nucleic acids in length and encompasses, for example, fragments consisting of nucleic acids 1-100, 300-400, 500-600, 800-900 of SEQ ID NOs: 1-1558 or fragments of similar length at the 3' end of SEQ ID NOs: 1-1558. A "fragment" can also mean a stretch of at least about 100 consecutive nucleotides that contains one or more deletions, insertions or substitutions. A "fragment" can also mean the whole coding sequence of a gene and may include 5' and 3' untranslated regions. A "fragment" can also refer to polypeptide sequences which are preferably at least about 5 to about 15 amino acids in length, most preferably at least about 10 amino acids long, and which retain some biological activity or immunological activity of a sequence. [0021] The term "gene" or "genes" refers to the partial or complete coding sequence of a gene. The term also refers to 5' or 3' untranslated regions of a transcript. The phrase "gene differentially expressed in osteoarthritis" refers to a gene whose amount of mRNA expressed from that gene or the amount of gene product translated from the mRNA is detectably different, i.e. either greater or lesser, in cells from subjects having osteoarthritis or in pre-osteoarthritic subjects compared to the amount of mRNA or translated gene product in cells from normal subjects which are neither osteoarthritic nor pre-osteoarthritic. As used herein, "pre- osteoarthritis" or "pre-osteoarthritic" is intended to mean that a subject is predisposed to developing osteoarthritis at a later date, but may not have any overt signs or symptoms of osteoarthritis. Preferably, the abundance of transcription or translation products of a differentially expressed gene derived from an osteoarthritic or pre-osteoarthritic sample differs by least about 1.15 fold, more preferably at least about 1.2 fold, more preferably at least about 1.3 fold, more preferably at least about 1.4 fold, more preferably at least about 1.5 fold, , more preferably at least about 1.6 fold, more preferably at least about 1.75 fold, more preferably at least about 2 fold, more preferably at least about 3 fold, more preferably at least about 10 fold, more preferably at least about 20 fold than that in a normal sample. The phrase "gene differentially expressed in osteoarthritis" also refers to genes that are not detectable in the normal transcript profile but are preferably at levels of at least about 2 copies per cell, more preferably at least about 3 copies per cell, in the osteoarthritic or pre-osteoarthritic tissue transcript profile. [0022] The terms "osteoarthritis (OA)-related" and "osteoarthritis (OA)-associated genes" refer to genes that are differentially expressed in osteoarthritis as defined herein. [0023] As used herein, the terms "reporter," "reporter system," "reporter gene," or "reporter gene product" refer to an operative genetic system in which a nucleic acid comprises a gene that encodes a product that when expressed produces a reporter signal that is a readily measurable, e.g., by biological assay, immunoassay, radioimmunoassay, or by colorimetric, fluorogenic, chemiluminescent or other methods. The nucleic acid may be either RNA or DNA, linear or circular, single or double stranded, antisense or sense polarity, and is operatively linked to the necessary control elements for the expression of the reporter gene product. The required control elements will vary according to the nature of the reporter system and whether the reporter gene is in the form of DNA or RNA, but may include, but not be limited to, such elements as promoters, enhancers, translational control sequences, poly A addition signals, transcriptional termination signals and the like. [0024] The terms "transform," "trahsfect," "transduce," refer to any method or means by which a nucleic acid is introduced into a cell or host organism and may be used interchangeably to convey the same meaning. Such methods include, but are not limited to, transfection, electroporation, microinjection, PEG-fusion and the like. [0025] The term "functional" as used herein implies that the nucleic or amino acid sequence is functional for the recited assay or purpose. [0026] The phrase "consisting essentially of" when referring to a particular nucleotide or amino acid means a sequence having the properties of a given SEQ ID NO. For example, when used in reference to an amino acid sequence, the phrase includes the sequence per se and molecular modifications that would not affect the basic and novel characteristics of the sequence. [0027] A "vector" is a replicon, such as a plasmid, cosmid, bacmid, phage, artificial chromosome (BAC, YAC) or virus, into which another genetic sequence or element (either DNA or RNA) may be inserted so as to bring about the replication of the attached sequence or element. A "replicon" is any genetic element, for example, a plasmid, cosmid, bacmid, phage, artificial chromosome (BAC, YAC) or virus, that is capable of replication largely under its own control. A replicon may be either RNA or DNA and may be single or double stranded. [0028] The term "probe" as used herein refers to either a probe for a nucleic acid or a probe for a protein. When used in connection with nucleic acids, a "probe" refers to an oligonucleotide, polynucleotide or nucleic acid, either RNA or DNA, whether occurring naturally as in a purified restriction enzyme digest or produced synthetically, which is capable of annealing with or specifically hybridizing to a nucleic acid with sequences complementary to the probe. A probe may be either single stranded or double stranded. The exact length of the probe will depend upon many factors, including temperature, source of probe and method of use. For example, for diagnostic applications, depending on the complexity of the target sequence, an oligonucleotide probe typically contains about 10-100, preferably about 15-50, more preferably about 15-25 nucleotides. In certain diagnostic applications, a polynucleotide probe preferably contains about 90-1150 nucleotides, more preferably about 300-600 nucleotides, more preferably about 300 nucleotides. The probes herein are selected to be "substantially" complementary to different strands of a particular target nucleic acid sequence. This means that the probes must be sufficiently complementary so as to be able to "specifically hybridize" or anneal with their respective target strands under a set of pre-determined conditions. Therefore, the probe sequence need not reflect the exact complementary sequence of the target. For example, a non complementary nucleotide fragment may be attached to the 5 ' or 3' end of the probe, with the remainder of the probe sequence being complementary to the target strand. Alternatively, non complementary bases or longer sequences can be interspersed into the probe, provided that the probe sequence has sufficient complementarity with the sequence of the target nucleic acid to anneal therewith specifically. When used in connection with a protein, a "probe" is a protein binding substance capable of specifically binding a particular protein or protein fragment to the substantial exclusion of other proteins or protein fragments. Such binding substances may be any molecule to which the protein or peptide specifically binds, including DNA (for DNA binding proteins), antibodies (as described in greater detail herein), cell membrane receptors, peptides, cofactors, lectins, sugars, polysaccharides, cells, cell membranes, organelles and organellar membranes. [0029] "Array" refers to an ordered arrangement of at least two probes on a substrate. At least one of the probes represents a control or standard, and the other, a probe of diagnostic interest. The arrangement of from about two to about 40,000 probes on a substrate assures that the size and signal intensity of each labeled complex formed between a probe and a sample nucleic acid or protein binding substance is individually distinguishable. [0030] A "hybridization complex" is formed between nucleic acid molecules of a sample when the purines of one molecule hydrogen bond with the pyrimidines of the complementary molecule, e.g., 5 -A-G-T-C-3' base pairs with 3'-T-C-A-G-5'. The degree of complementarity and the use of nucleotide analogs affect the efficiency and stringency of hybridization reactions. [0031] The term "specifically hybridize" refers to the association between two single stranded nucleic acid molecules of sufficiently complementary sequence to permit such hybridization under pre determined conditions generally used in the art (sometimes termed "substantially complementary"). For example, the term may refer to hybridization of a nucleic acid probe with a substantially complementary sequence contained within a single stranded DNA or RNA molecule according to an aspect of the invention, to the substantial exclusion of hybridization of the nucleic acid probe with single stranded nucleic acids of non-complementary sequence. [0032] "Sample" is used in its broadest sense as containing nucleic acids, proteins, antibodies, and the like. A sample may comprise, for example, a bodily fluid; the soluble fraction of a cell preparation, or an aliquot of media in which cells were grown; a chromosome, an organelle, or membrane isolated or extracted from a cell; genomic DNA, RNA, or cDNA in solution or bound to a substrate; a cell; a tissue or a tissue biopsy; a tissue print; a fingerprint, buccal cells, skin, or hair; and the like. [0033] A "standard" refers to a control sample that comprises material from a source in a normal (as opposed to OA-related) biological state. An OA-related biological state may include, for example, one in which the source has OA, is predisposed to develop OA, or exhibits certain biological characteristics of OA. For example, a standard sample may comprise nucleic acids or proteins from a normal subject that is not osteoarthritic or pre-osteoarthritic. Standard samples may also include samples from normal cells or tissue that have not been treated to elicit an immune response that may model certain aspects of OA. [0034] "Specific binding" refers to a special and precise interaction between two molecules which is dependent upon their structure, particularly their molecular side groups. For example, the intercalation of a regulatory protein into the major groove of a DNA molecule, the hydrogen bonding along the backbone between two single stranded nucleic acids, or the binding between an epitope of a protein and an agonist, antagonist, or antibody. [0035] The term "primer" as used herein refers to a nucleic acid molecule, either RNA or DNA, either single stranded or double stranded, either derived from a biological system, generated by restriction enzyme digestion, or produced synthetically which, when placed in the proper environment, is able to functionally act as an initiator of template-dependent nucleic acid synthesis. When presented with an appropriate nucleic acid template, suitable nucleoside tnpnospnate precursors ot nucleic acids, a polymerase enzyme, suitable cofactors and conditions such as appropriate temperature and pH, the primer may be extended at its 3' terminus by the addition of nucleotides by the action of a polymerase or similar activity to yield an primer extension product. The primer may vary in length depending on the particular conditions and requirement of the application. For example, in diagnostic applications according to particular embodiments of the invention, a primer may be an oligonucleotide primer, preferably about 15 - 25 or more nucleotides in length. The primer must be of sufficient complementarity to the desired template to prime the synthesis of the desired extension product, that is, to be able anneal with the desired template strand in a manner sufficient to provide the 3' hydroxyl moiety of the primer in appropriate juxtaposition for use in the initiation of synthesis by a polymerase or similar enzyme. It is not required that the primer sequence represent an exact complement of the desired template. For example, a non complementary nucleotide sequence may be attached to the 5' end of an otherwise complementary primer. Alternatively, non complementary bases may be interspersed within the oligonucleotide primer sequence, provided that the primer sequence has sufficient complementarity with the sequence of the desired template strand to functionally provide a template primer complex for the synthesis of the extension product. [0036] Amino acid residues described herein are preferred to be in the "L" isomeric form. However, residues in the "D" isomeric form may be substituted for any L amino acid residue, provided the desired properties of the polypeptide are retained. All amino acid residue sequences represented herein conform to the conventional left-to-right amino terminus to carboxy terminus orientation. [0037] A "fragment" or "portion" of a polypeptide means a stretch of amino acid residues of at least about five to seven contiguous amino acids, often at least about seven to nine contiguous amino acids, typically at least about nine to thirteen contiguous amino acids and, most preferably, at least about twenty to thirty or more contiguous amino acids. Fragments of the polypeptide sequence, antigenic determinants, or epitopes are useful for eliciting immune responses to a portion of the protein amino acid sequence. [0038] Different "variants" of the differentially expressed polypeptides exist in nature. These variants may be alleles characterized by differences in the nucleotide sequences of the gene coding for the protein, or may involve different RNA processing or post translational modifications. The skilled person can produce variants having single or multiple amino acid substitutions, deletions, additions or replacements. These variants may include, inter alia: (a) variants in which one or more amino acids residues are substituted with conservative or non conservative amino acids, (b) variants in which one or more amino acids are added to the p'olypeptide, (c) variants in which one or more amino acids include a substituent group, and (d) variants in which the polypeptide is fused with another peptide or polypeptide such as a fusion partner, a protein tag or other chemical moiety, that may confer useful properties to the polypeptide, such as, for example, an epitope for an antibody, a polyhistidine sequence, a biotin moiety and the like. Other polypeptides of the invention may include variants in which amino acid residues from one species are substituted for the corresponding residue in another species, either at the conserved or non conserved positions. In another embodiment, amino acid residues at non conserved positions are substituted with conservative or non conservative residues. The techniques for obtaining these variants, including genetic (suppressions, deletions, mutations, etc.), chemical, and enzymatic techniques are known to the person having ordinary skill in the art. To the extent such allelic variations, analogues, fragments, derivatives, mutants, and modifications, including alternative nucleic acid processing forms and alternative post translational modification forms result in derivatives of the differentially expressed polypeptide that retain any of the biological properties of the differentially expressed polypeptide, they are included within the scope of this invention. [0039] The term "isolated protein" or "isolated and purified protein" refers primarily to a protein produced by expression of an isolated nucleic acid molecule according to an aspect the invention. Alternatively, this term may refer to a protein that has been sufficiently separated from other proteins with which it would naturally be associated, so as to exist in "substantially pure" form. "Isolated" is not meant to exclude artificial or synthetic mixtures with other compounds or materials, or the presence of impurities that do not interfere with the fundamental activity, and that may be present, for example, due to incomplete purification, addition of stabilizers, or compounding into, for example, immunogenic preparations or pharmaceutically acceptable preparations. [0040] The term "substantially pure" refers to a preparation comprising at least about 50-60% by weight of a given material (e.g., nucleic acid, protein, etc.). More preferably, the preparation comprises at least about 75% by weight, and most preferably about 90-95% by weight of the given compound. Purity is measured by methods appropriate for the given material (e.g. chromatographic methods, agarose or polyacrylamide gel electrophoresis, HPLC analysis, and the like). [0041] The term "tag," "tag sequence" or "protein tag" refers to a chemical moiety, either a nucleotide, oligonucleotide, polynucleotide or an amino acid, peptide or protein or other chemical, that when added to another sequence, provides additional utility or confers useful properties, particularly in the detection or isolation, of that sequence. Thus, for example, a homopolymer nucleic acid sequence or a nucleic acid sequence complementary to a capture oligonucleotide may be added to a primer or probe sequence to facilitate the subsequent isolation of an extension product or hybridized product. In the case of protein tags, histidine residues (e.g., 4 to 8 consecutive histidine residues) may be added to either the amino or carboxy terminus of a protein to facilitate protein isolation by chelating metal chromatography. Alternatively, amino acid sequences, peptides, proteins or fusion partners representing epitopes or binding determinants reactive with specific antibody molecules or other molecules (e.g., flag epitope, c myc epitope, transmembrane epitope of the influenza A viras hemagglutinin protein, protein A, cellulose binding domain, calmodulin binding protein, maltose binding protein, chitin binding domain, glutathione S transferase, and the like) may be added to proteins to facilitate protein isolation by procedures such as affinity or immunoaffinity chromatography. Chemical tag moieties include such molecules as biotin, which may be added to either nucleic acids or proteins and facilitates isolation or detection by interaction with avidin reagents, and the like. Numerous other tag moieties are known to, and can be envisioned by, the trained artisan, and are contemplated to be within the scope of this definition. [0042] An "antibody" or "antibody molecule" is any immunoglobulin, including antibodies and fragments thereof, that binds to a specific antigen. The term includes polyclonal, monoclonal, chimeric, and bispecific antibodies. As used herein, antibody or antibody molecule contemplates both an intact immunoglobulin molecule and an immunologically active portion of an immunoglobulin molecule such as those portions known in the art as Fab, Fab', F(ab')2 and F(v). [0043] As used herein, the term "subject" or "patient" refers to both humans and animals, unless specified that the "subject" or "patient" is an animal or a human. Animal subjects are preferably vertebrates, and more preferably, mammals. [0044] "Therapeutic modality" refers to any means of treating and/or preventing a disease, condition or disorder. [0045] In one aspect of the present invention, a number of genes have been identified that are differentially expressed in osteoarthritic subjects as compared to non-osteoarthritic subjects. These genes and gene fragments, as well as their encoded proteins and fragments, may be used, for example, in a variety of diagnostic and prognostic assays, as well as assays useful in screening test substances for effectiveness in treatment modalities for osteoarthritis. [0046] In certain embodiments of the invention, expression of at least one differentially expressed gene may be measured. In preferred embodiments, expression of two or more differentially expressed genes may be measured, providing a gene expression pattern or gene expression profile. More preferably, measurement of a multiplicity of differentially expressed genes may be performed, providing additional information for a gene expression pattern or profile. [0047] In various embodiments of the present invention, changes in gene expression may be measured in one or both of two ways: (1) measuring transcription through detection of mRNA produced by a particular gene; and (2) measuring translation through detection of protein produced by a particular transcript. [0048] Decreased or increased expression can be measured at the RNA level using any of the methods well known in the art for the quantitation of polynucleotides, such as, for example, PCR (including, without limitation, RT-PCR and qPCR), RNase protection, Northern blotting and other hybridization methods. The genes that are assayed or interrogated according to the present invention are typically in the form of mRNA or reverse transcribed mRNA. The genes may be cloned and/or amplified. The cloning itself does not appear to bias the representation of genes within a population. However, it may be preferable to use polyA+ RNA as a source, as it can be used with fewer processing steps. [0049] In accordance with aspects of the present invention, 1558 genes have been identified whose functions are closely associated with osteoarthritis (OA). The association is determined by comparing expression of the genes in normal tissue and tissue from subjects diagnosed with OA. The genes so identified fall into two broad categories. The first category comprises known genes, many of whose association with OA had heretofore been unappreciated. These genes are listed in Table 6, along with their corresponding gene ID numbers and SEQ ID NOs. [0050] According to another aspect of the invention, a second category comprises nucleic acid segments that do not demonstrate homology to previously identified sequences. Thus, this category is believed to include one or more novel genes. One preferred embodiment of the invention relates to an isolated nucleic acid molecule comprising a novel OA-associated gene, mRNA or cDNA produced from the OA-associated gene. [0051] One aspect of the present invention relates to a combination of 1558 polynucleotide molecules that are differentially expressed in an osteoarthritic subject or in a pre- osteoarthritic subject compared to expression in subjects which are not osteoarthritic or pre- osteoarthritic. In one embodiment of the invention described herein, segments of 1558 OA- related genes from canine cartilage were obtained by employing differential display. The nucleotide sequences of these polynucleotides are set forth herein asSEQ ID NOs: 1-1558 (Table 1 shows the correlation between SEQ ID NO. and Gene ID Number). BLAST analysis of these sequences identified homologies with of a number of nucleic acid sequences previously identified (Table 2) These include a number of previously identified nucleic acid sequences with no identified homologies to known genes. BLAST analysis also identified sequences showing homology to previously-identified genes; information including names of genes as well as database accession numbers for respective homologs of these is provided in Tables 2A and 2B. Table 2A

Table 2B

994b PF00415 IPR000408 PF00651 IPR002110 IPR000210

CaMax: RS20_HU 603682 NM_001023 PF00338 IPR001687 RPS20 996a MAN IPR001848

[0052] One embodiment of the invention relates to a combination comprising two or more polynucleotide molecules selected from SEQ ID NOs: 1-1558, or fragments thereof. Preferably, the combination comprises about 10 or more polynucleotide molecules, more preferably about 50 or more polynucleotide molecules, more preferably about 200 or more polynucleotide molecules, more preferably about 400 or more polynucleotide molecules, more preferably about 1000 or more polynucleotide molecules. [0053] In a preferred embodiment, the invention relates to a combination of 396 differentially expressed polynucleotide molecules, whose sequences are represented by SEQ ID NOs: 1-396. Table 3 identifies a list of gene sequences determined from clinical samples to be differentially expressed in OA versus normal subjects to a degree that is statistically significant (p < 0.05). Table 3 includes the gene IDs, expression values, standard deviations, and fold difference of expression (OA versus normal). Preferably, the combination comprises two or more of polynucleotide molecules selected from SEQ ID NOs: 1-396 or fragments thereof. [0054] In a particularly preferred embodiment, the invention relates to a combination of

217 differentially expressed polynucleotide molecules, whose sequences are represented by SEQ ID NOs: 1-217. Table 4 identifies a list of gene sequences determined from clinical samples to be differentially expressed in OA versus normal subjects to a degree that is highly significant (p < 0.01). Table 4 includes the gene IDs, expression values, standard deviations, and fold difference of expression (OA versus normal). Preferably, the combination comprises two or more of polynucleotide molecules selected from SEQ ID NOs: 1-217 or fragments thereof. [0055] According to an aspect of the invention, one or more oligonucleotide or polynucleotide probes for interrogating a sample may be prepared using the sequence information set forth herein for any of the 1558 isolated gene fragments (SEQ ID NOs: 1-1558). According to another aspect of the invention, probes may be prepared using the sequence information available for any of the genes or gene fragments identified in . The probes should be of sufficient length to specifically hybridize substantially exclusively with appropriate complementary genes or transcripts. Preferably, the oligonucleotide probes will be at least about 10, 12, 14, 16, 18, 20 or 25 nucleotides in length. In some embodiments, longer probes of at least about 30, 40, 50, 60, 70, 80, 90 or 100 nucleotides are desirable, and probes longer than about 100 nucleotides may be suitable in some embodiments. Preferably, a collection of two or more nucleic acid probes for detecting expression of gene products differentially expressed in OA is provided, more preferably a collection of about 10 or more probes, more preferably a collection of about 50 or more probes, more preferably a collection of about 200 or more probes, more preferably a collection of about 400 or more probes, more preferably a collection of about 1000 or more probes. [0056] In a preferred embodiment of the invention, one or more oligonucleotide or polynucleotide probes may be prepared using the sequence information set forth for any of SEQ ID NOs: 1-396. Preferably, one or more oligonucleotide or polynucleotide probes may be prepared using the sequence information set forth for any of SEQ ID NOs: 1-217. [0057] In certain preferred embodiments of the present invention, immobilized nucleic acid probes may be used for the rapid and specific detection of nucleic acid molecules and their expression patterns. Typically, a nucleic acid probe is linked to a solid support and a target nucleic acid (e.g., a genomic nucleic acid, an amplicon, or, most commonly, an amplified mixture) is hybridized to the probe. Either the probe, or the target, or both, can be labeled, typically with a fluorophore or other tag, such as streptavidin. Where the target is labeled, hybridization may be detected by detecting bound fluorescence. Where the probe is labeled, hybridization is typically detected by quenching of the label. Where both the probe and the target are labeled, detection of hybridization is typically performed by monitoring a color shift resulting from proximity of the two bound labels. A variety of labeling strategies, labels, and the like, particularly for fluorescent based applications, are known in the art. [0058] Another aspect of the invention relates to one or more probes comprising polypeptide binding agents that specifically bind to polypeptides produced by expression of one or more nucleic acid molecules comprising sequences selected from SEQ ID NOs: 1-1558 or fragments thereof. According to another aspect of the invention, protein binding probes may be prepared using the sequence information available for any of the genes or gene fragments identified in Table 2. Preferably, a collection of two or more polypeptide probes for detecting expression of gene products differentially expressed in OA is provided, more preferably a collection of about 10 or more probes, more preferably a collection of about 50 or more probes, more preferably a collection of about 200 or more probes, more preferably a collection of about 400 or more probes, more preferably a collection of about 1000 or more probes. [0059] In a preferred embodiment of the invention, probes comprising polypeptide binding agents specifically bind to polypeptides produced by nucleic acid molecules comprising sequences selected from SEQ ID NOs: 1-396. In a particularly preferred embodiment, probes comprising polypeptide binding agents specifically bind to polypeptides produced by nucleic acid molecules comprising sequences selected from SEQ ID NOs: 1-217. [0060] Assay techniques that can be used to determine levels of a protein in a sample are also well known to those of skill in the art. Such assay methods include radioimmunoassays, competitive-binding assays, Western blot analysis and ELISA assays. In the assay methods utilizing antibodies, both polyclonal and monoclonal antibodies are suitable for use in the present invention. Such antibodies may be immunologically specific for a particular protein, or an epitope of the protein, or a protein fragment, as would be well understood by those of skill in the art. Methods of making polyclonal and monoclonal antibodies immunologically specific for a protein or peptide are also well known in the art. [0061] Preferred embodiments of the present invention may utilize antibodies for the detection and quantification of proteins produced by expression of the polynucleotides described herein. Though proteins may be detected by immunoprecipitation, affinity separation, Western blot analysis and the like, a preferred method utilizes ELISA-type methodology wherein the < antibody is immobilized on a solid support and a target protein or peptide is exposed to the immobilized antibody. Either the probe, or the target, or both, can be labeled. A variety of labeling strategies, labels, and the like, are known in the art. [0062] In particularly preferred embodiments of the invention, expression patterns or profiles of a plurality of genes differentially expressed in osteoarthritis are observed utilizing arrays of probes for detecting target nucleic acids or proteins. In one embodiment, arrays of oligonucleotide or polynucleotide probes may be utilized, whereas another embodiment may utilize arrays of antibodies or other proteins that bind specifically to the differentially expressed gene products. Such arrays are commercially available (e.g,. through Affymetrix, Inc., Applied Biosystems, Inc., Agilent, Inc.), or they may be custom made according to known methods, such as, for example, in-situ synthesis on a solid support or attachment of pre-synthesized probes to a solid support via micro-printing techniques. In preferred embodiments, arrays of nucleic acid or protein-binding probes are custom made to specifically detect transcripts or proteins produced by two or more of the 1558 differentially expressed genes or gene fragments described herein. In one embodiment of the invention, arrays of nucleic acid or protein-binding probes are custom made to specifically detect transcripts or proteins produced by two or more of the genes or gene fragments identified in Table 2. In a preferred embodiment, arrays of nucleic acid or protein- binding probes are custom made to specifically detect transcripts or proteins produced by two or more of the 396 differentially expressed genes or gene fragments identified in Table 3. In a preferred embodiment, arrays of nucleic acid or protein-binding probes are custom made to specifically detect transcripts or proteins produced by two or more of the 217 differentially expressed genes or gene fragments identified in Table 4. [0063] Preferably, a collection of two or more nucleic acid or polypeptide probes for detecting expression of gene products differentially expressed in OA is immobilized on a support in discrete locations, more preferably a collection of about 10 or more probes, more preferably a collection of about 50 or more probes, more preferably a collection of about 200 or more probes, more preferably a collection of about 400 or more probes, more preferably a collection of about 1000 or more probes. [0064] Since chondrocytes represent the cellular component of cartilage, a tissue affected by OA, the construction of a chondrocyte array may represent a powerful tool to study the gene expression profile of osteoarthritic chondrocytes. The use of differential display for transcript selection was used by the present inventors to enrich the clones represented on an array for transcripts associated with OA. , [0065] In one aspect of the invention, methods are provided for assaying OA-associated nucleic acids in a sample. Preferably, a combination comprising one or more polynucleotide molecules selected from SEQ ID NOs: 1-1558, more preferably selected from SEQ ID NOs:l- 396, more preferably selected from SEQ ID NOs: 1-217, are used to prepare probes that are hybridized with nucleic acids of a test sample, forming hybridization complexes that are detected and compared with those of a standard, such that differences between the sample and standard hybridization complexes are indicative of differential expression of nucleic acids in the sample. In a preferred embodiment, nucleic acid probes are made to specifically detect transcripts or fragments thereof produced by one or more of the genes or gene fragments identified in Table 2. In certain preferred embodiments, the nucleic acids of the sample may be amplified prior to hybridization. [0066] In another aspect of the invention, methods are provided for assaying OA- associated polypeptides in a sample. Preferably, polynucleotide sequences selected from SEQ ID NOs: 1-1558, more preferably selected from SEQ ID NOs: 1-396, more preferably selected from SEQ ID NOs: 1-217 are used to prepare protein-binding probes that specifically bind to translation products of those polypeptides or fragments thereof. These probes are reacted with a test sample, forming binding complexes that are detected and compared with those of a standard, such that differences between the sample and standard binding complexes are indicative of differential expression of polypeptides in the sample. In a preferred embodiment, protein- binding probes are made to specifically detect polypeptides or fragments thereof produced by one or more of the genes or gene fragments identified in Table 2. [0067J According to certain preferred embodiments of the invention, the assays described herein for the detection of OA-associated transcription and translation products may be used in methods useful for determining a diagnosis and/or prognosis for osteoarthritis in a patient. According to an embodiment of the invention, a typical diagnostic test will comprise obtaining a sample of cells or tissue from a patient in which OA-associated gene expression is expected to occur. Such cells or tissues include, but are not limited to, cartilage tissue and chondrocytes. The sample is then analyzed for either 1) increased or decreased expression of one or more selected genes, via detection of mRNA or protein, or 2) a particular gene expression profile, for example, via gene or protein array technology, as described herein. Such a diagnostic procedure should lead to a determination of whether indications of osteoarthritis are present in the patient. [0068] In another embodiment of the invention, the diagnostic procedures described herein may also be extended to provide prognostic information regarding a patient's recovery from OA, or to monitor a patient's progress in response to a therapeutic regimen. In these situations, the diagnostic assay is performed at intervals during the patient's recovery or course of treatment, and a change in expression of a target gene, or a particular change in the pattern of gene expression, is indicative of the patient's level of recovery or improvement. [0069] In one aspect of the invention, assays are provided for identifying substances effective in treatment modalities for osteoarthritis. In one embodiment of the invention, a method is provided for measuring the effect of a test substance on the expression profile of genes differentially expressed in osteoarthritis, comprising the steps of: a) obtaining a standard expression profile from a first sample by measuring transcription or translation products of two or more genes corresponding to two or more genes or gene fragments identified in Tables 1 and/or 2 in the absence of the test substance; b) obtaining a test expression profile from a second sample by measuring the transcription or translation products of two or genes or gene fragments identified in Tables 1 and/or 2 expressed in the presence of the test substance; c) comparing the standard expression profile the test expression profile, wherein a change in the test expression profile compared to the standard expression profile is indicative of an effect of the test substance on the expression profile of genes differentially expressed in osteoarthritis compared to a non- osteoarthritic condition. Preferably, the two or more genes or gene fragments correspond to two or more of the genes or gene fragments identified in Table 3 (SEQ ID NOs: 1-396). More preferably, the two or more genes or gene fragments correspond to two or more of the genes or gene fragments identified in Table 4 (SEQ ID NOs: 1-217). In certain preferred embodiments, the samples are obtained from cultured cells. In this case, the standard expression profile is obtained from cells that have not been contacted with the test substance, while the test expression profile is obtained from cells that have been contacted with a test substance. [0070] Test compounds may include proteins, polypeptides, nucleic acids, small molecule pharmaceuticals, vitamins, minerals, fatty acids, polysaccharides, extracts, nutriceuticals, and the like. In a preferred embodiment, the test compounds are nutrients that may be added to food or other dietary substances, or that may be taken as a dietary supplement. As exemplified herein, such nutrients include, but are not limited to, fatty acids such as omega-3 fatty acids (e.g., eicosapentaenoic acid) and omega-6 fatty acids (e.g., arachidonic acid), glucosamine, chondroitin sulfate and vitamin D derivatives such as lα,25-dihydroxyvitamin D3 and 24R,25-dihydroxy vitamin D3. [0071] One type of assay according to an embodiment of the invention involves measuring the activity of the protein encoded by one of the aforementioned OA-associated genes in the presence or absence of a candidate substance. Such activity assays are well known in the art. If a cell-free activity assay is available for the selected protein, such an assay is simply conducted on the purified protein in the presence or absence of the test substance. Candidate substances are selected based on their ability to positively or negatively regulate activity of the purified protein. It should be noted that assays of this type may be performed, for example, in a recombinant cellular system, as described below. They can also be performed, for example, in a cell-free system in some instances. [0072] For such in vitro activity assays, it is desirable to have a source of the purified protein of interest. One or more of the protein products of the genes mentioned above may be commercially available, or purifiable in significant quantities from an appropriate biological source, e.g., cultured cells. Alternatively, the proteins may be recombinantly produced from an isolated gene or cDNA by expression in a suitable procaryotic or eucaryotic expression system, and thereafter purified, as is also well known in the art. [0073] Another embodiment of the invention comprises in vitro cellular assays for expression of OA-associated genes or activity of their encoded proteins. For these embodiments, a nucleic acid construct comprising an OA-associated gene according to an aspect of the invention is introduced into host cells. In a preferred embodiment, mammalian cell lines are utilized. Host cells contemplated for use include, but are not limited, to NIH3T3, CHO, HELA, and COS, as well as non-mammalian cells such as yeast, bacteria and insect cells. The coding sequences are operably linked to¹ appropriate regulatory expression elements suitable for the particular host cell to be utilized. Methods for introducing nucleic acids into host cells are well known in the art. Such methods include, but are not limited to, transfection, transformation, calcium phosphate precipitation, electroporation and lipofection. The recombinant cells may be used to identify compounds which modulate expression of the OA-associated genes or activity of their encoded proteins. / [0074] For gene expression assays, it is preferred to prepare an artificial construct comprising the promoter of a selected OA-associated gene, operably linked to a reporter gene. The reporter construct may be introduced a cultured cell, including, without limitation, the standard host cell lines described above, or other suitable cells, for example, cartilage-related cells such as chondrocytes. The assay is performed by monitoring expression of the reporter gene in the presence or absence of a test compound. Candidate substances are selected based on their ability to positively or negatively affect expression of the gene. [0075] In another embodiment of the invention, OA-associated genes and gene fragments described herein may be used to manipulate the genome of non-human animal subjects. Methods of manipulating the genomes of a variety of animals are known to those of skill in the art. Such methods may include, without limitation, the production of transgenic and gene-knockout animals. In a preferred embodiment of the invention, a gene or gene fragment identified in Table 2 is used to prepare a construct that is used to disrupt or "knock out" the corresponding endogenous gene in an animal, thus producing an animal having a null mutation for that gene locus. In some embodiments, the animals exhibit a reduction or complete elimination of the expression of one or more genes having a nucleic acid sequence selected from SEQ ID NOs: 1-1558. In some embodiments, the animals exhibit a reduction or complete elimination of the expression of one or more genes having a nucleic acid sequence selected from SEQ ID NO: 1-396. In some embodiments, the animals exhibit a reduction or complete elimination of the expression of one or more genes having a nucleic acid sequence selected from SEQ ID NO: 1-217. In other embodiments, the animals exhibit a reduction or complete elimination of the expression of one or more genes shown in Table 6. The transgenic animals are preferably mammals. In some embodiments, the transgenic animals are rodents (e.g., mice and rats). In other embodiments, the animals are, for example, goats, cats, dogs, cows, pigs, sheep, horses, non-human primates, rabbits, and guinea pigs. In some embodiments, small interfering RNAs are used to functionally disrupt the genes. Briefly, gene expression is inhibited by a short interfering RNA (siRNA) through RNA interference (RNAi) or post-transcriptional gene silencing (PTGS) (see, for example, Ketting et al. (2001) Genes Develop. 15:2654-2659). siRNA molecules can target homologous mRNA molecules for destruction by cleaving the mRNA molecule within the region spanned by the siRNA molecule. Accordingly, siRNAs capable of targeting and cleaving mRNA of the gene products shown in Table 6 may be used to decrease or eliminate expression of one or more of these genes. In other embodiments, siRNAs capable of targeting and cleaving mRNA of one or more of the genes shown in Table 1 (SEQ ID NOS: 1-1558) may be used to decrease or eliminate expression of one or more of these genes. [0076] In another embodiment of the invention, OA-associated genes and gene fragments described herein are used to design molecules that may be used to interfere with the expression of one or more OA-associated genes; such molecules may include, without limitation, RNA interference probes and antisense molecules. [0077] Another aspect of the invention features compositions of matter to facilitate practice of the assays described above. These compositions may comprise collections of two or more probes or primers for use in detecting differentially expressed OA-related genes, gene fragments and encoded proteins according to certain aspects of the invention. In one embodiment, the compositions may comprise collections of two or more oligonucleotides or polynucleotides that specifically hybridize with nucleic acid molecules selected from SEQ ID NOS:l-1558. Preferably, the compositions may comprise collections of two or more oligonucleotides or polynucleotides that specifically hybridize with nucleic acid molecules selected from SEQ ID NOS: 1-396. More preferably, the compositions may comprise collections of two or more oligonucleotides or polynucleotides that specifically hybridize with nucleic acid molecules selected from SEQ ID NOS: 1-217. Preferably, the composition may comprise collections of two or more oligonucleotides or polynucleotides that specifically hybridize with genes and/or gene fragments selected from the genes and gene fragments identified in Table 2. The collection may comprise a primer pair for amplifying the sequence. In certain preferred embodiments, amplification may be performed using Polymerase Chain Reaction (PCR), more preferably quantitative PCR (qPCR). In a preferred embodiment, the collection comprises a larger plurality of probes, e.g., about 10, 50, 200, 400, 1000 or more probes, each of which hybridizes specifically with part or all of one of the sequences of SEQ ID NOS: 1-1558. In a preferred embodiment, nucleic acid probes are immobilized on a solid support. In a particularly preferred embodiment, they are immobilized in an array format, most preferably in a miniature or micro-array. Such micro-arrays are known in the art, and are sometimes referred to as "DNA chips," "microchips," "biological chips" and other similar terms, and may contain the entire array of genes or gene fragments altered by OA, in addition to those represented in Tables 1 and 2. [0078] In another embodiment, these compositions comprise two or more protein binding substances capable of specifically binding proteins or protein fragments encoded by the genes and gene fragments identified in Tables 1 and 2. In a preferred embodiment the binding substances are antibodies and the collection comprises two or more antibodies for detecting two or more proteins or peptides encoded by SEQ ID NOS: 1-1558, respectively. Preferably, these compositions comprise two or more protein binding substances capable of specifically binding proteins or protein fragments encoded by the genes and gene fragments of SEQ ID NOS: 1-396. More preferably, these compositions comprise two or more protein binding substances capable of specifically binding proteins or protein fragments encoded by the genes and gene fragments of SEQ ID NOS: 1-217. Such binding substances may be any molecule to which the protein or peptide specifically binds, including DNA (for DNA binding proteins), antibodies, cell membrane receptors, peptides, cofactors, lectins, sugars, polysaccharides, cells, cell membranes, organelles and organellar membranes. In a preferred embodiment, the collection comprises a larger plurality of antibodies, e.g., about 10, 50, 200, 400, 1000 or more, each of which binds immunospecifically with part or all of a protein or peptide encoded by genes or gene fragments identified in Tables 1 and/or 2. In a preferred embodiment, the antibodies are immobilized on a solid support. In a particularly preferred embodiment, they are immobilized in an array format, most preferably in a miniature or micro-array, as described above for oligonucleotide probes, and may contain the entire array of proteins altered by OA, in addition to genes or gene fragments identified in Tables 1 and 2. [0079] Another embodiment of the present invention relates to substances or compounds identified in any of the methods described herein as having an effect on the expression profile of genes differentially expressed in OA. Preferably, such substances will be effective in the treatment and/or prevention of OA. [0080] Still another aspect of the invention features test kits for use in one or more of the assays described herein. One type of kit comprises one or more pairs of primers for amplifying nucleic acids corresponding to the OA-associated genes and gene fragments described herein. The kit may further comprise samples of total mRNA derived from tissue of various physiological states, for use as controls. The kit may also comprise buffers, nucleotide bases, and other compositions to be used in hybridization and/or amplification reactions. Each solution or composition may be contained in a vial or bottle and all vials held in close confinement in a box for commercial sale. [0081] Another type of kit comprises one or more nucleic acid or protein-binding probes, wherein the nucleic acid probe hybridizes specifically with a OA-associated gene or gene fragment according to certain aspects of the invention, or the protein-binding probe specifically binds to a protein encoded by the OA-associated gene or gene fragment. Preferably, the protein- binding probe is an antibody that is immunologically specific for the protein encoded by the OA- associated gene or gene fragment. In preferred embodiments, the nucleic acid or protein-binding probes are immobilized on a solid support. In a particularly preferred embodiment, the kit comprises immobilized arrays of nucleic acid or protein-binding probes, the arrays comprising probes specific for a plurality of the OA-associated genes or gene fragments described herein, or proteins encoded thereby. These kits also may contain appropriate control samples of mRNA or protein from tissues of known physiological state, to be used as controls in the assays. They may further comprise buffers and reagents for performing the assays. Each solution, reagent or composition in the kit may be contained in a vial or bottle and all vials held in close confinement in a box for commercial sale. Preferably, kits may further comprise instructions for performing an assay of gene expression. [0082] In another aspect, the invention provides a method for altering biological profile of cells through inducing a change in the gene expression profile of the cells with respect to genes involved in OA. The method involves administering to cells an effective amount of a compound that alters the expression of one or more genes having a nucleic acid sequence selected from SEQ ID NOs: 1-1558. In some embodiments, the compound affects the expression of one or more genes having a nucleic acid sequence selected from SEQ ID NOs: 1-396. In some embodiments, the compound affects the expression of one or more genes having a nucleic acid sequence selected from SEQ ID NOs: 1-217. In other embodiments, the compound affects the expression of one or more genes having the gene products shown in Table 6. The invention also provides a method of affecting the expression of genes involved in OA comprising exposing cells to an effective amount of a compound that modulates expression of one or more genes having a sequence selected from SEQ ID NOs: 1-1558. In some embodiments, the compound affects the expression of one or more genes having a nucleic acid sequence selected from SEQ ID NOs: 1-396. In some embodiments, the compound affects the expression of one or more genes having a nucleic acid sequence selected from SEQ ID NOs: 1-217. In other embodiments, the compound affects the expression of one or more genes having the gene products shown in Table 6. [0083] In some embodiments the cells are cells associated with symptoms of osteoarthritis. In some embodiments the cells are chondrocytes. In some embodiments the compounds are administered to cells in vitro. In other embodiments the compounds are administered to cells in vivo. The compounds may be administered to subjects via any route of administration. Preferably, the subjects are vertebrates. More preferably, the subjects are mammals including dogs, cats and humans. [0084] The change in gene expression is preferably at least a 1.01 fold difference. More preferably, it is at least a 1.05, 1.10, 1.25, 1.50, 1.75, 2.0, 2.25, 2.50, 2.75, 3.0, 3.25, 3.50, 3.75, 4.0 fold difference or more. [0085] Chondroitin sulfate was shown to have an effect on a wide variety of OA- associated genes as shown in detail in Tables 7-12. Glucosamine was also found to have an effect on a variety of OA-associated genes as shown in detail in Tables 13-18. lα,25- dihydroxyvitamin D3 and 24R,25-dihydroxyvitamin D3 also affected the expression of OA- related genes as shown in Tables 19-20. Eicosapentaenoic acid (EPA) and arachidonic acid (AA) were also shown to affect OA-related genes as shown in Tables 21-23.

[0086] The following examples are provided to describe the invention in greater detail. They are intended to illustrate, not to limit, the invention.

EXAMPLE 1

Extraction of RNA from chondrocytes [0087] Normal and osteoarthritic canine cartilage chondrocytes (N₂-flash frozen) were obtained and stored at -80°C. Osteoarthritic chondrocytes originated from canines clinically diagnosed with osteoarthritis undergoing total hip replacement. 300 to 500 mg were ground in N₂ (mortar and pestle) and transferred to a clean, pre-chilled, 50 ml tube. Trizol (2ml/100mg) was added and the mixture was homogenized using a Polytron for 2 x 30 seconds, and 1 minute (high speed). The homogenate was then centrifuged at 10,000 x g for 10 minutes at 4° C. The supernatant was removed and 0.2 volumes chloroform added to the supernatant, vortexed, and centrifuged at 10,000 x g for 15 minutes at 4° C. The upper aqueous phase was removed and 5 volumes of 4 M Guanidine thiocyanate, 25 mM sodium citrate, 0.5% sarkosyl, 0.1 M beta- mercaptoethanol and .475 volumes of 100 % ethanol were added to the upper aqueous phase. The solution was then applied to Qiagen RNAqueous mini-columns (cat # 74104), using a vacuum manifold (according to the manufacture's directions) for further purification of the RNA. The purified RNA was then ethanol precipitated to concentrate, resuspended in DEPC water and DNAse I treated to remove residual DNA. The DNA- ree™ DNAse Treatment kit from Ambion (cat #1906) was used for DNAse I treatment according to the manufacture's directions. [0088] RNA was quantitated in a Beckman DU 640B spectrophotometer at 260 nm (Beckman Coulter, Inc.,4300 N. Harbor Boulevard, P.O. Box 3100, Fullerton, CA 92834-3100). Absorbance of 1 at 260nm is equivalent to 40 μg RNA/ml. Typical yields were 0.65 to 0.8 μg/μl. Quality of RNA was determined by the absorbance at 260 nm/280 nm with a typical ratio of 1.7 - 2.0. Quality was also assessed by electrophoresis in a 1% agarose gel/formaldehyde/Tris-borate-EDTA (TBE), pH 7.8 buffer (90mM Tris, 90mM boric acid, 2mM EDTA). Approximately 1 to 3.5 μg RNA was loaded (2 to 5 μl) after being mixed with 15 μl gel loading solution (lOmM Tris pH 7.5, ImM EDTA, 0.02% bromophenol blue, 10% glycerol). The gel was run at 50 Volts for 3-4 hours, stained with SYBR Green I (Molecular Probes, Inc., PO Box 22010 ,Eugene, OR 97402-0469, 4849 Pitchford Ave., Eugene, OR 97402-9165 ) at a dilution of 1:10,000 for 30 minutes in the dark and scanned using a Hitachi FMBIO II Fluorescent scanner at 505 nm (Hitachi Genetic Systems, 1201 Harbor Bay Parkway Ste. 150, Alameda, CA 94502). Example 2

Differential Display [0089] Fluorescent differential display was performed using one of three anchored primers in combination with one of 80 arbitrary primers (GenHunter). In all, 240 PCR reactions were carried out. Reactions were separated using PAGE and visualized using a fluorescent scanner (FMBIOII, Hitachi). Bands representing differentially expressed genes were excised, reamplified and run on an agarose gel to verify size. These were subsequently subcloned (PCR- TRAP, GenHunter) and sequenced. [0090] Differential display was performed using GenHunter' s RNAimage® kit or RNAspectra™ green fluorescent mRNA differential display systems (GenHunter Corporation, 624 Grassmere Park Drive, Suite 17, Nashville, TN 37211). Approximately 200 ng of RNA was reverse transcribed in the following reaction (final concentration): RT buffer (25 mM Tris-Cl, pH 8.3, 37.6 mM KC1, 1.5 mM MgCl₂, 5 mM DTT), 625 μM ea. dNTP, 50 pmol H-T_πG primer (GenHunter) (5'AAGCTTTTTTTTTTTG 3') (SEQ ID NO:1559), or H-TnC primer (GenHunter) (5'AAGCTTTTTTTTTTTC 3') (SEQ ID NO:1560), or H-TnA primer (GenHunter) (5'AAGCTTTTTTTTTTTA 3') (SEQ ID NO: 1561), in a total volume of 19 μl. lμl (100 units/μl) of MMLV reverse transcriptase was added ten minutes into the 37°C step in a thermocycler (GeneAmp PCR System 9700, PE Applied Biosystems, 850 Lincoln Center Dr., Foster CA 94404) and the following reaction performed: 65°C 5 minutes, 37°C 60 minutes, 75°C 5 minutes followed by a hold at 4°C. Two μl of the reverse transcription reaction was used in the following polymerase chain reaction: PCR buffer (lOmM Tris-Cl, pH 8.4, 50 mM KC1, 1.5 mM MgCl₂, 0.001% gelatin), 50 μM each dNTP, 5 pmol Fluorescein-labeled H-T_nG primer (GenHunter) (Fluorescein-labeled primer, 5' AAGCTTTTTTTTTTTG 3') (SEQ ID NO:1562), or Fluorescein-labeled H-TπC primer (GenHunter) (Fluorescein-labeled primer, 5' AAGCTTTTTTTTTTTC 3') (SEQ ID NO: 1563) or Fluorescein-labeled H-T_πA primer (GenHunter) (Fluorescein-labeled primer, 5' AAGCTTTTTTTTTTTA 3') (SEQ ID NO: 1564) one of the H-AP primers provided in the kit at 200 pM, 1 unit of Amplitaq DNA polymerase (PE Applied Biosystems, 850 Lincoln Center Dr., Foster CA 94404 ) in a total of 20 μl. [0091] The following thermocycler reaction was used: 40 cycles of 94°C 15 seconds,

40°C 2 minutes, 72°C 30 seconds, followed by 72°C 5 minutes and a 4°C hold. o [0092] 5 μl of each PCR sample was mixed with 5 μl blue dextran loading buffer and

10 μl deionized formamide and electrophoresed on a 6% polyacrylamide gel at 55 watts for 3 hours in TBE buffer. The gel was scanned using a Hitachi FMBIO II at 505 nm. cDNA bands differentially expressed were excised with a razor, placed in a 1.5 ml tube, soaked in 100 μl sterile water for 10 minutes and then boiled for 15 minutes. Tubes were centrifuged for 2 minutes at 10,000 x g and the supernatant transferred to a new tube. 10 μl 3M sodium acetate, 5 μl glycogen (10 mg ml) and 450 μl 100% ethanol was added to the supernatant and the tubes were placed at -80°C overnight. Samples were centrifuged at 10,000 x g for 10 minutes at 4 °C and the supernatant was removed. cDNA pellets were washed with cold (-20°C) 85% ethanol, spun as above for 1 minute and the supernatant was removed. cDNA pellets were resuspended in 10 μl sterile water. [0093] Four μl samples of the cDNA extracts were amplified the same as in the above

PCR reaction with the following exceptions: 40 μl total reaction volume; 20 μM ea. dNTP; 200 pM unlabeled primer H-TnG , H-TπC , or H-TnA (GenHunter) and 2 units of Amplitaq DNA polymerase (PE Applied Biosystems). PCR conditions were the same as above. 15 μl of the amplified cDNA extracts were mixed with 3 μl 6X loading dye (0.25% bromophenol blue,

0.25% xylene cyanol FF, 30% glycerol) and electrophoresed in a 1.5% agarose gel. The gel was run at 100 volts for 2 to 3 hours in TBE buffer, stained/visualized the same as above. Bands were excised with a razor and cDNA extracted according to Qiagen' s QIAEX® II Gel Extraction

Kit (Qiagen, Inc., 28159 Avenue Stanford, Valencia, CA 91355). Three hundred μl QX1 buffer and 10 μl QIAEX® II suspension was added to each gel slice in a 1.5 ml tube and incubated at

50°C for 10 minutes. Tubes were vortexed every 2 minutes during incubation. Tubes were centrifuged 10,000 x g for 30 seconds and the supernatant was discarded. Pellets were washed once with 500 μl Buffer QX1 and twice with buffer PE (vortexing and centrifuging as above for each wash). Pellet was air dried for 10 minutes and 20 μl sterile water was added. Tubes were incubated for 5 minutes at room temperature and cDNA was eluted by centrifugation as above for 30 seconds. Supernatant was then transferred to a new 1.5 ml tube and stored at -20°C. [0094] Amplified gel purified cDNA was subcloned according to GenHunter' s PCR- TRAP® Cloning System Kit (GenHunter Corporation, 624 Grassmere Park Drive, Suite 17, Nashville, TN 37211). 5 μl amplified gel purified cDNA was added to 300 ng PCR-TRAP® vector, ligase buffer (50 mM Tris-Cl, pH 7.8, 10 mM MgCl₂, 10 mM DTT, 10 mM ATP, 5 μg BSA) and 200 units T4 DNA ligase, mixed, and incubated overnight at 16°C. GH competent cells (E. coli del(lac-pro) ara thi (φ80dZαcZdelM15)) were transformed with ligation reaction by mixing 10 μl ligation reaction to 100 μl GH competent cells on ice in 1.5 ml tubes. Tubes were incubated on ice for 45 minutes, heat shocked at 42°C for 2 minutes and then incubated on ice for 2 minutes. 400 μl LB broth (Luria-Bertani, Difco) was added to each tube and the tubes were incubated at 37°C for 1 hour with shaking (250 rpm). 200 μl of these transformations were plated onto LB-agar-tet plates (LB-agar, Difco, tetracycline 20 μg/ml) and incubated overnight at 37°C. [0095] Colonies were checked for insert using GenHunter' s colony lysate PCR protocol. Colonies were picked with a clean pipette tip and placed in 50 μl colony lysate buffer (GenHunter, TΕ with 0.1% Tween 20) in a microfuge tube. Tubes were boiled for 10 minutes, centrifuged at 10,000 x g for 2 minutes and the corresponding lysate (supernatant) was transferred to a new microfuge tube. 2.0 μl of lysate was added to PCR buffer, 20 μM ea. dNTP, 200 pmol ea. of Lgh (5' CGACAACACCGATAATC) (SΕQ ID NO: 1565) and Rgh (5' GACGCGAACGAAGCAAC) (SΕQ ID NO: 1566) primers and 1 unit of Amplitaq DNA polymerase (PΕ Applied Biosystems) in a total volume of 20 μl. The following thermocycler reaction was used: 30 cycles of 94°C for 30 seconds, 52°C for 40 seconds and 72°C for 1 minute followed by 72°C for 5 minutes and a 4°C hold. PCR products were analyzed in a 1.5% agarose gel the same as above. [0096] 3-5 ml LB broth was inoculated with appropriate colonies and incubated overnight at 37°C at 250 rpm. Plasmids were isolated according to Qiagen' s QIAprep Plasmid protocol. Bacteria were pelleted (10,000 x g, 30 seconds) using 2 x 1.5 ml inoculated broth and the supernatant was removed. Pelleted bacteria were resuspended in 250 μl buffer PI, 250 μl buffer P2 was then added and tubes were mixed by gentle inversion. 350 μl buffer N3 was added, tubes were mixed by gentle inversion and then centrifuged for 10 minutes. Supernatants were added to a QIAprep column and centrifuged for 30 seconds. Flow-throughs were discarded, 0.5 ml of buffer PB was added to column and tubes were centrifuged for 30 seconds. Columns were washed with 0.75 ml buffer PE and centrifuged for 30 seconds. Flow-throughs were discarded and tubes were spun an additional minute. DNA was eluted from the column by adding 50 μl sterile water to the column. The column was incubated at room temperature for 1 minute and then centrifuged for 1 minute. Resulting supernatant containing plasmid DNA was quantitated as above (absorbance of 1 at 260 nm equals 50 μg/ml) with a typical yield of 350 μg/ml and a 260nm/280nm ratio of 1.8. [0097] Sequencing reactions used 200 to 500 ng plasmid DNA in the ABI Prism BigDye Terminator Cycle Sequencing Ready Reaction Kit (PE Applied Biosystems, 850 Lincoln Center Dr., Foster CA 94404). 0.8 μl of primer (0.16 μm final concentration of either Lgh or Rgh, GenHunter) was added to plasmid DNA along with 4.0 μl Teminatόr Reaction Mix (containing AmpliTaq DNA Polymerase, FS, deoxynucleoside triphosphates, MgCl₂, Tris-HCL buffer, pH 9.0, A-Dye Terminator labeled with dichloro(R6G), C-Dye Terminator labeled with dichloro(ROX), G-Dye Terminator labeled with dichloro(R110) and T-Dye Terminator labeled with dichloro(TAMRA)) and brought to a final volume of 10 μl with sterile water. The following thermocycler reaction was used: 25 cycles of 96°C for 10 seconds, 50°C for 5 seconds, 60°C for 4 minutes followed by a 4°C hold. [0098] Unincorporated dye-terminators were removed from the sequencing reactions according to Qiagen' s DyeEx spin protocol. Prepared DyeEx spin columns were placed in 2.0 ml microfuge tubes and centrifuged at 750 x g for 3 minutes. Columns were placed in new tubes, sequencing reactions were added to columns and centrifuged, as above, for 3 minutes. The eluate was placed at 74°C until dry. [0099] 5 μl of formamide/blue dextran (5:1 ratio) was added to each dried sequencing pellets. 1.5 μl to 2.0 μl was then added to a 5% polyacrylamide gel (in TBE buffer) on a Perkin Elmer ABI Prism 377 automated DNA sequencer. [0100] Each isolated plasmid clone was sequenced 2-6 times (2-6 different sequencing reactions, 1-3 times for each primer, Lgh or Rgh). Sequence files from the ABI 377 sequencer were transferred to Genetic Computer Group's Wisconsin Package and a corresponding consensus sequence was determined. [0101] Approximately 1750 clones were isolated using differential display. All genes that appeared to be differentially expressed were selected. A representational polyacrylamide gel image is shown in Figure 1. Panel A represents the gel prior to band excision and panel B represents the same gel after band excision. Sizes of clones ranged from 90 b.p. to 1150 b.p., with an average size of 300 b.p. After filtering the sequences for redundant sequences, dimers, E. coli fragments, fragments <100 b.p. etc., 1558 remained. Sequences obtained (SEQ ID NOs:l- 1558) are shown in Table 1, which is appended herewith and which forms part of the present specification. [0102] The sequences obtained were BLASTed against the human, mouse and dog public domain genomes to get a first hit. To be considered a hit at this stage, the match had to cover more than 50% of the sequence and an Expect value (E value) of less than 0.002. The first hits were used to extend the sequence using the respective genome. The sequences were either extended 2kb to the 5' or 3' side of the hit. The extended sequences were then used to BLAST against public domain protein databases (Ensembl, swissprot/trembl). The respective hits (those with an Expect value of less than 0.002, in this case) were consolidated and used for the annotations. In some cases, this strategy did not give hits, and in these situations the original sequences were BLASTed directly against swissprot/trembl or Ensembl proteins. In this case, hits were considered when the Expect value was less than 0.002. [0103] Results of BLAST analysis (as of 1/28/04) of sequences isolated by differential display are shown in Table 2, which is appended herewith and which forms part of the present specification. The sequences are listed in the leftmost column by the gene ID designations (clone numbers) employed by the inventors herein. Many sequences matched with a Description of a previously-identified gene; the Description column also includes the source database and the corresponding database accession number. Table 2 includes additional information from a number of databases, including Ensemble Gene IDs, Ensemble Transcript IDs, Swissprot/Ensemble, OMDVI (Online Mendelian Inheritance in Man), RefSeq, Pfam, InterPro and HUGO. Information is also shown regarding Chromosome Number (#) and Chromosome Location for many of the sequences. Additionally, the column labeled "Signal peptide" indicates the sequences for which a predicted signal peptide occurs in the amino acid sequence; the column labeled "TMHMM" (Transmembrane Hidden Markov Model) indicates sequences for which a predicted transmembrane region occurs in a protein sequence. Table 6 lists clones demonstrating homology to previously-identified genes. Table 6

EXAMPLE 3 Preparation of Microarray [0104] Microarray probes were generated by PCR-amplifying clones isolated from differential display. Probes were spotted in duplicate onto poly-L-lysine coated slides using a GMS417 (Affymetrix) arrayer. Osteoarthritic cartilage samples were obtained from the femoral heads of clinically diagnosed canines undergoing total hip replacement. RNA was hybridized to the slides using the HC Express Array (Digene) kit and visualized using a GMS418 (Affymetrix) scanner. The Imagene (Biodiscovery) program was used for spot finding and subsequent data analysis was performed using GeneSight (Biodiscovery). Expression levels are represented after background subtraction, log (base 2) transformation and global slide signal normalization. Microarray clone preparation [0105] Culture blocks containing 1.5 mLs of Magnificent Broth (MB) plus tetracycline (50 mg/mL) were inoculated with appropriate clones from glycerol stocks and grown overnight with shaking at 37°C. These cultures were used to inoculate a second culture block that was grown for approximately 6 hours with shaking at 37°C. These 6-hour cultures were used to inoculate 2 replicate culture blocks which were grown overnight with shaking at 37°C. Cultures were centrifuged to pellet cells and plasmids isolated using the Qiagen 96-well culture system (Qiagen). Plasmid concentrations Were determined using a spectrophotometer by measuring the absorbance at 260nm. All cDNA plasmid clones were amplified in duplicate using the following PCR reaction (final concentration): 10X PCR buffer (lOmM Tris-HCl, pH 8.3, 50mM KC1, 2.5mM MgCl₂), 500uM ea. dNTP, 600 nM Rgh primer, 600 nM Lgh primer, lμL (5units/μL) of Eppendorf Taq polymerase and lμL (~100ng/μL) cDNA template in a total of lOOμL. The reaction was performed in the following conditions: 94°C 30 seconds, 52°C 40 seconds, 72°C 1 minute for 40 cycles, followed by 72°C - 5min and 4°C - hold. Amplified products were verified on 1.5% agarose gel and purified using Minelute (Qiagen) protocol. The 200μL of PCR was added to the filter plate and vacuum was turned on to pull through all¹ PCR reagents and liquid leaving only the cDNA bound to the filter. 30μL molecular grade water was added to the filter plate and incubated at room temperature on an orbital shaker at 900 rpm for 5 minutes. The supernatant containing the purified cDNA was aspirated from the filter plate. The cDNA's were dried for 2hrs or to completion in a speed vac at 45°C. 30μL Corning Universal Printing Buffer was added to all cDNA's and resuspended over night at room temperature on an orbital shaker. 2μL's transferred for concentration analysis and the appropriate amount of Corning Universal Printing Buffer was added for a final concentration of 200 to 500 ng/uL. Plates were stored at - 20 °C until and after each array printing. Clone arraying [0106] Microscope slides (Goldseal cat# 3010) were submerged in a 10% NaOH (Fisher cat#S318-500) 57% EtOH solution and incubated at room temperature in an orbital shaker at 50rpm for 2 hours. Slides were rinsed in Milli-Q water 5X for 30 seconds each. While the slides remain in the last water rinse a 10% Poly-L-Lysine (Sigma cat#P8920), 10% IX PBS (GibcoBRL cat#70013-032) was brought to 700mLs using Milli-Q water in plastic ware. Slides were submerged in coating solution and incubated at room temperature in orbital shaker at 50rpm for 1 hour. Slides were rinsed in Milli-Q water 5X for 30 seconds each and spun at 500rpm for 1 minute. Slides were incubated in 55°C oven for 10 min and kept in dessicator for at least 14 days and no longer than 3 months prior to arraying. cDNA clones were arrayed using the GMS 417 arrayer (Affymetrix). All slides were placed in a room temperature dessicator to dry overnight. The slides were rehydrated over boiling Milli-Q water (steam) and snap dried DNA side up on an 80°C heat block. To ensure efficient cross-linking the slides were baked for 2 hours at 80°C in an oven and then cross-linked with Stratalinker (120mJ, Stratagene). All slides were stored in a room temperature dessicator until used for cDNA hybridization.

cDNA microarray hybridization [0107] All RNA samples were reverse transcribed using the following reaction: 5X Superscript II First Strand Buffer (Invitrogen), luL (Ipmole/uL) of RT primer (Genisphere), luL Superase-In™ Rnase inhibitor, luL lOmM ea. DNTP, 2uL 0.1 M DTT, luL Superscript II and 5ug total RNA. The reaction was performed at 42°C for 2hrs. The reaction was stopped by adding 3.5uL of 0.5 M NaOH/50 mM EDTA and incubating at 65°C for 10 minutes. The reaction was neutralized by adding 5uL of IM Tris-HCL, pH 7.5. 101.5uL of lOmM Tris, pH 8, ImM EDTA was added and the cDNA was purified and concentrated by following the Microcon YM-30 (Millipore) protocol. The concentrated cDNA was brought to a final volume of lOuL with Nuclease-free water and the following reagents added: 20ul of 2X hybridization buffer (Genisphere), 2uL dT LNA blocker and 8uL Nuclease-free water for a total of 40uL. The hybridization mixture was heated at 80°C for 10 minutes and loaded onto the microarray slide at the edge of the lifterSlip. The slide was then placed into a GeneMachines dual hybridization chamber and placed in a 60°C water bath overnight. The following day the slides were processed according to the 3DNA Array 350 (Genisphere) protocol. Briefly, the slides were washed (2XSSC-.2%SDS, 2X SSC, .2X SSC), spun dry at lOOOrpm for 1 min and the 3DNA capture hybridization performed. The slides were washed (2XSSC-.2%SDS, 2X SSC, .2X SSC) spun dry at lOOOrpm for 1 min and scanned using a GMS 418 array scanner (Affymetrix). Microarray analysis [0108] , Scanned images representing RNA transcripts bound to specific clones were quantified and checked for spot quality control using Imagene analysis software (BioDiscovery). Quantified images were analyzed using Genesight analysis software (BioDiscovery). The analysis represented subtraction of background surrounding the spots, averaging spot replicates, deletion of clone information representing clone hybridization signals not greater than 200 above background on all samples, log (base 2) transformation and global normalization of each slide (values expressed as percent of average spot intensity).

EXAMPLE 4 Expression Analysis Using Microarray [0109] RNA was extracted from cartilage as described, supra. Microarray analysis (described supra) was performed on 8 osteoarthritic cartilage samples from clinically diagnosed canines undergoing total hip replacement and 8 normal cartilage samples. A standard T-test (two categories) was performed on the final hybridization signals for osteoarthritic characterization of cartilage samples (p<0.05 and p<0.01, results shown in Tables 3 and 4, respectively). TABLE 3

TABLE 4

[0110] The use of differential display to isolate gene transcripts has enabled the present inventors to develop a microarray chip enriched in transcripts involved in osteoarthritis. The use of this chip to analyze samples from canines with osteoarthritis (1) confirms the results from differential display and (2) enables further characterization of canine osteoarthritis at the molecular level. Transcripts analyzed by qPCR (discussed infra) have validated the differential expression analysis from the microarray.

EXAMPLE 5

Quantitative Polymerase Chain Reaction (qPCR) / [0111] Confirmation of changes in RNA transcripts was performed using quantitative

PCR. Reverse transcriptase reactions were performed using Super Script™ II Reverse

Transcriptase for RT-PCR (Invitrogen) according to the manufacture's directions, lμg of RNA was added to 1.5μL10 mM dNTP's, 1.5μL random hexamers and 0.6μL Oligo dT primers and brought to a final volume of 15 uL. Samples were incubated at 68°C for 10 minutes and then brought down to 4°C for at least 1 minute using a GeneAmp PCR System 9700 (Applied

Biosystems). A portion (0.25X) of the above reaction was removed and used as a minus RT reaction (Negative Control containing No Super Script™ II Reverse Transcriptase). Using the same Super Script™ II Reverse Transcriptase kit, a master mix containing 3μL of 10X RT buffer, 6μL of 25mM MgCl₂, 3μL 0.1M DTT and 1.5μL RNAse Inhibitor was made. A portion

(0.25X) was removed and 0.375μL H₂O was added for the minus RT samples. To the remainder of the Master Mix, 1.125μL Super Script™ II Reverse Transcriptase was added for the positive

RT reactions. All reactions were then incubated at 42°C for lhour, boiled at 95°C for 5minutes, and the brought down to 4°C using a GeneAmp PCR System 9700. The samples were then diluted 1 part RT reaction to 29 Parts H₂O to create a stock of cDNA for experimentation. [0112] Primers and 5' nuclease assay probes were designed based on selected sequences from the differential display using Primer Express vl.5 (Applied Biosystems Primer Express® Tutorial for Real Time Quantitative PCR Primer and Probe Design Tutorial). Minor groove Binding probes (ABI Custom Oligo Synthesis Factory) were ordered from ABI. All oligos were reconstituted with TE buffer pH=8.0 (Ambion) to lOOμM stock concentration, and then diluted with TE buffer to a 5μM working stock concentration. TaqMan® Universal PCR Master Mix (Applied Biosystems) was used for quantitative PCR reactions according to the manufacture's directions. Primer concentration was 300μM each and Probe concentration was 200μM (determined optimal from earlier experiments). 4μl of RT and minus RT reactions were used for quantitative PCR reactions. All positive reactions were done in triplicate, and negative controls were performed singly. Standard qPCR conditions were used as described in the TaqMan® Universal Master Mix (Applied Biosystems, 50.0°C for 2 minutes, 95.0°C for 10 minutes, and 40-50 cycles of 95°C for 15 seconds then 60°C for 1 minute) at 0.5 volumes. Samples were run on an ABI Prism 7700 Sequence Detector using ABI Sequence Detector Program vl.7a. [0113] All samples were run singularly against each primer/probe set to determine what standard curve should be used. Standard curves were generated using serial dilutions of liver RNA or RNA from experimental samples. Alternately, if the samples did not fall within either of the curve ranges, the sample with the lowest C_τ (cycle threshold) would be re-reverse transcribed and a 1:10 serial dilution would be used as the standard curve for that primer/probe set. Values were normalized to G3PDH (glyceraldehyde-3-phoshate dehydrogenase) levels as determined by quantitative PCR. Inductions were calculated from each of the lowest sample's normalized value. Error bars represent standard error of the means. [0114] Table 5 shows the primers and probes used for the qPCR analysis.

TABLE 5

EXAMPLE 6 qPCR analysis of Canine OA Cartilage [0115] qPCR was performed as described, supra, on 6 osteoarthritic cartilage samples from clinically diagnosed canines undergoing total hip replacement and 8 normal cartilage samples. Results are shown in Figure 2 (A-E).

EXAMPLE 7 Microarray Analysis of Treated OA Samples

A. In Vitro Chondrocyte Cell Culture [0116] Canine cartilage was digested in a 37°C shaking water bath using the following enzymes: trypsin (0.25%) for 25 minutes, hyaluronidase (150U/ml) for 1 hour, and collagenase (0.78%) overnight. Digested cartilage was filtered to obtain chondrocytes. Dulbecco's Modified Eagle Medium (DMEM) + 2.4% alginate (low melting) + cells were dropped from a lOcc syringe into calcium chloride (102 mM) to form "beads." Chondrocyte beads were cultured in DMEM/F12 + P/S (100 U/mL penicillin and 100 μg/mL streptomycin) + 10% Fetal Bovine Serum (FBS). Media was changed every other day. At the end of the treatment (see below), the chondrocyte beads were dissolved in sodium citrate (55mM) and EDTA (30mM). Suspensions were centrifuged at 1800 rpm for lOminutes. Cells were washed with phosphate buffer and centrifuged again at 1800 rpm for 5 minutes. One mL lysis binding solution (Ambion® RNAqueous™) was added to the isolated canine chondrocyte pellet, mixed thoroughly and stored at -20°C until RNA isolation could be performed.

B. RNA Isolation from Cell Culture [0117] Samples were vortexed and homogenized using a Quiashredder (Qiagen) column according to manufacture's directions. The homogenized lysate was collected and 1 equal volume of 64% ethanol was added to it. This mixture was then applied to an RNAqueous™ filter cartridge, 700 uL at a time, and centrifuged for 1 minute at 10,000 rpm. The cartridge was washed using 700uL wash solution #1 and 500 uL wash solution #2/3 with centrifugation at 10,000 rpm for 1 minute for each wash. The filter cartridge was dried by centrifugation (10,000 rpm) for 1 minute. RNA was eluted 3 times by centrifugation (as above) using 30 uL aliquots of 95-100°C elution solution. The resulting RNA was DNAse-treated and quantitated as stated previously. Following RNA isolation, the RNA was prepared for microarray hybridization as stated previously.

C. Statistical Analysis of Cell Culture Microarray [0118] Data were transformed to logarithm, base 2. Data were normalized using quantile normalization. After normalization, a concordance correlation was computed. [0119] Differentially expressed genes were determined using a paired t test (α=0.05) for the EPA vs. AA; EPAstim'vs. AAstim; chondroitin sulfate and glucosamine lOOμg vs. control, lOOμg vs. lOμg and lOμg vs. control. [0120] Differentially expressed genes were determined by first using ratios of AAstim vs. AA and EPAstim vs. EPA followed by a paired t test (α=0.05) for the ratios of AAstim/ AA and EPAstim EPA. [0121] Differentially expressed genes following a unidirectional trend for all glucosamine and chondroitin sulfate analyses were determined for each treatment pair where responses to the treatment resulted in increases or decreases, in the same direction, in all three samples. [0122] Differentially expressed genes were determined using a Welch modified two- sample t test for both 1,25 D3 vs. control and 24,25 D3 vs. control (α=0.05).

1. Chondroitin Sulfate Treatment [0123] Chondrocytes were treated with chondroitin sulfate based on the recognition of chondroitin sulfate as a joint nutrient. Chondrocyte beads were treated with 100 μg/mL, 10 μg/mL or 0 μg/mL (control) chondroitin sulfate (n=3) for 1 week in DMEM/F12 + P/S + 10% FBS. Media was changed every other day. After one week, the chondrocytes beads were dissolved in sodium citrate (55mM) and EDTA (30mM). Suspensions were centrifuged at 1800 rpm for lOminutes. Cells were washed with phosphate buffer and centrifuged again at 1800 rpm for 5 minutes. One mL lysis binding solution (Ambion® RNAqueous™) was added to the isolated canine chondrocyte pellet, mixed thoroughly and stored at ^~20°C until RNA isolation could be performed. One sample from the chondroitin sulfate treatment was removed due to poor correlation with the rest of the array data. This reduced this analysis to an n=3. The results are shown in Tables 7-12.

TABLE 7: Differential Expression of OA -Associated Genes with Chondroitin Sulfate Treatment Comparing the Effect of 100 μg/mL and 10 μg/mL Chondroitin Sulfate on

2. Glucosamine Treatment [0124] Glucosamine treatment was used to determine the effect of this joint health nutrient on the differential expression of OA-associated genes. Chondrocyte beads were treated with 100 μg/mL, 10 μg/mL or 0 μg/mL (control) glucosamine (n=3) for 1 week in DMEM/F12 + P/S + 10% FBS. Media was changed every other day. After one week, the chondrocytes beads were dissolved in sodium citrate (55mM) and EDTA (30mM). Suspensions were centrifuged at 1800 rpm for lOminutes. Cells were washed with phosphate buffer and centrifuged again at 1800 rpm for 5 minutes. One mL lysis binding solution (Ambion® RNAqueous™) was added to the isolated canine chondrocyte pellet, mixed thoroughly and stored at ^~20°C until RNA isolation could be performed. The results are shown in Tables 13-18.

TABLE 14: Differential Expression of OA-Associated Genes with Glucosamine Treatment Comparing the Effect of 100 μg/mL and 0 μg/mL (Control) Glucosamine on Chondrocytes (p<0.5) Gene ID DIF (100-C) Fold

3. lα,25-dihydroxyvitamin D₃ (1,25 D3) and 24R,25-dihydroxyvitamin D₃ (24,25 D3) Treatment [0125] 1,25 D3 and 24R,25D3 treatment was applied to chondrocytes based on their known effects on prostaglandin production and differential responses to the vitamin D3 metabolites in chondrocytes to determine the effect of these compounds on OA-associated gene expression. Chondrocyte beads were treated with 10^"7M 1,25 D3 or 10^"7M 24,25 D3 for 24 hours or without Vitamin D (equivalent ethanol was added to control), (n=3) in DMEM/F12 + P/S + 10% FBS. After 24 hours, the chondrocyte beads were dissolved in sodium citrate (55mM) and EDTA (30mM). Suspensions were centrifuged at 1800 rpm for 10 minutes. Cells were washed with phosphate buffer and centrifuged again at 1800 rpm for 5 minutes. One mL lysis binding solution (Ambion® RNAqueous™) was added to the isolated canine chondrocyte pellet, mixed thoroughly and stored at -20°C until RNA isolation could be performed. The results are shown in Tables 19 and 20.

4. Eicosapentaenoic acid (EPA) and Arachidonic Acid (AA) Treatment [0126] Chondrocytes were treated with eicosapentaenoic acid (EPA) and arachidonic acid (AA) based on the recognition in the literature that EPA acts as an anti-inflammatory. AA was used as a control to represent a typical western diet. Chondrocytes were enriched with 50μM EPA or 50μM AA (using albumin as a carrier) for two weeks in DMEM/HAMS + P/S + 10% FBS. Media was changed every other day. Each set (n=3) was split and half were treated with stimulated monocyte neutrophil conditioned media (SMNCM) for one week with media changed every other day. SMNCM was made by isolating monocytes and neutrophils from canine whole blood using NycoPrep™ according to the manufacture's directions. Monocytes and neutrophils were stimulated with lipopolysaccharide (20ng/mL) for 72 hours. The resulting supernatant was used as SMNCM in cell culture experimentation (SMNCM made up 10% of media used during experimentation). Chondrocyte beads were dissolved in sodium citrate (55mM) and EDTA (30mM). Suspensions were centrifuged at 1800 rpm for lOminutes. Cells were washed with phosphate buffer and centrifuged again at 1800 rpm for 5 minutes. One mL lysis binding solution (Ambion® RNAqueous™) was added to the isolated canine chondrocyte pellet, mixed thoroughly and stored at -20°C until RNA isolation could be performed. One sample from the EPA/ AA stim treatment was removed due to poor correlation with the rest of the array data. This reduced these analyses to an n=3. The results are shown in Tables 21-23.

[0127] The experiments demonstrated that various treatments can affect the expression of OA-associated genes. In some cases, the effect on gene expression was statistically significant (p<0.05). In other cases, although the change could not be demonstrated to be statistically significant due to the variability of expression, there was a definite trend for expression to be changed in one direction only (either increased expression or decreased expression). This unidirectional change is considered to be both biologically relevant and significant. In some cases, it is believed that down-regulation of expression of certain genes will have a beneficial biological effect on OA. For other genes, increased expression will have a beneficial biological effect. The invention allows the identification of genes that correlate with beneficial effects as demonstrated by regulation of compounds known to be involved in anti- inflammatory processes, for example. The invention also permits the identification of new compounds which should have beneficial effects based on their regulation of gene expression of the OA-associated genes described in this invention. [0128] The results demonstrate that one can affect the biology of the cells with various treatments and have a direct impact on gene expression of OA-associated genes. The invention permits the rapid and powerful screening of compounds to identify candidate treatments and preventatives of OA in animals, particularly humans. [0129] The disclosures of each patent, patent application, publication and accession number to database sequences cited or described in this document are hereby incorporated herein by reference, in their entirety. [0130] Various modifications of the invention, in addition to those described herein, will be apparent to those skilled in the art from the foregoing description. Such modifications are also intended to fall within the scope of the appended claims.

Claims

What is Claimed:

1. A combination comprising a plurality of polynucleotide molecules wherein the polynucleotide molecules are differentially expressed in an osteoarthritic subject or in a pre- osteoarthritic subject compared to expression in subjects which are not osteoarthritic or pre- osteoarthritic.

2. The combination of claim 1, wherein the plurality of polynucleotide molecules comprises two or more molecules selected from SEQ ID NOs: 1-1558 or fragments thereof.

3. A method for the detection of differential expression of nucleic acids in a sample, comprising the steps of:

a) hybridizing a combination comprising a plurality of polynucleotide molecules wherein the polynucleotide molecules are differentially expressed in an osteoarthritic subject or in a pre- osteoarthritic subject compared to expression in subjects which are not osteoarthritic or pre- osteoarthritic with nucleic acids of the sample, thereby forming one or more hybridization complexes;

b) detecting the hybridization complexes; and

c) comparing the hybridization complexes with those of a standard, wherein differences between the standard and sample hybridization complexes indicate differential expression of nucleic acids in the sample.

4. The method of claim 3, wherein the polynucleotide molecules hybridize with nucleic acid sequences selected from SEQ ID NOs: 1-1558 or fragments thereof.

5. The method of claim 3, wherein the polynucleotide molecules hybridize with nucleic acid sequences selected from gene sequences identified in Table 2 or fragments thereof.

6. A method for the detection of differential expression of polypeptides in a sample, comprising the steps of:

a) reacting a combination comprising a plurality of protein binding molecules with polypeptides of the sample, thereby allowing specific binding to occur, wherein the proteins bound by the protein-binding molecules are differentially expressed in an osteoarthritic subject or in a pre- osteoarthritic subject compared to expression in subjects which are not osteoarthritic or pre- osteoarthritic;

b) detecting specific binding; and

c) comparing the specific binding in the sample with that of a standard, wherein differences between the standard and sample specific binding indicate differential expression of polypeptides in the sample.

7. The method of claim 3 or 6, further comprising the step of treating the sample with a test compound, wherein comparison to a standard is indicative of whether treatment with the test compound altered the differential expression of nucleic acids or polypeptides in the sample.

8. A composition of matter comprising a collection of two or more probes for detecting expression of genes differentially expressed in osteoarthritic or pre-osteoarthritic subjects compared to subjects that are not osteoarthritic or pre-osteoarthritic, wherein the probes comprise two or more of:

a) nucleic acid molecules that specifically hybridize to two or more of the genes or gene fragments identified in Tables 1 and 2, or fragments thereof; or

b) polypeptide binding agents that specifically bind to polypeptides produced by expression of two or more nucleic acid molecules comprising sequences selected from one or more of genes or gene fragments identified in Tables 1 and 2, or fragments thereof.

9. The composition of claim 8 wherein the genes or gene fragments comprise SEQ ID NOs:l- 1558 or fragments thereof.

10. The composition of claim 8 wherein the gene or gene fragments comprise genes or gene fragments identified in Table 2.

11. A device for detecting expression of a plurality of genes differentially expressed in osteoarthritis, comprising a substrate to which is affixed, at known locations, a plurality of probes, wherein the probes comprise: a) a plurality of oligonucleotides or polynucleotides, each of which specifically hybridizes to a different sequence selected from any of SEQ ID NOS: 1-1558 or fragments thereof; or

b) a plurality of polypeptide binding agents, each of which specifically binds to a different polypeptide or fragment thereof produced by expression of a nucleic acid molecule comprising a sequence selected from the genes or gene fragments comprising any of SEQ ID NOS: 1-1558 or fragments thereof.

12. A method for measuring the effect of a test compound on the expression of one or more genes differentially expressed in osteoarthritis, comprising the steps of:

a) measuring standard expression by measuring transcription or translation products of one or more of the genes or gene fragments comprising any of SEQ ID NOS: 1-1558, or fragments thereof, in a standard sample in the absence of the test compound; '

b) measuring test expression by measuring the transcription or translation products of one or more of the genes or gene fragments comprising any of SEQ ID NOS: 1-1558, or fragments thereof, in a test sample in the presence of the test compound;

c) comparing the standard expression to the test expression, wherein a change in the test expression compared to the standard expression is indicative of an effect of the test compound on the expression of genes differentially expressed in osteoarthritis compared to a non-osteoarthritic condition.

13. The method of claim 12, wherein said measuring utilizes a composition of matter comprising a plurality of probes, wherein the probes comprise two or more of two or more of the genes or gene fragments comprising any of SEQ ID NOS: 1-1558, or fragments thereof.

14. The method of claim 12, wherein the standard and test samples are obtained from at least one mammalian subject.

15. A method for measuring the effect of a test compound on expression of an OA-associated gene, wherein the gene is selected from the group consisting of the genes identified in Table 6, the method comprising measuring production of transcription or translation products produced by expression of the gene in the presence or absence of the test compound, wherein a change in the production of transcription or translation products in the presence of the test compound is indicative of an effect of the test compound on expression of the gene.

16. The method of claim 15, wherein the gene expression is measured by providing a DNA construct comprising a reporter gene coding sequence operably linked to transcription regulatory sequences of the OA-associated gene, and measuring formation of a reporter gene product in the presence or absence of .the test compound.

17. A method to diagnose or develop a prognosis for a subject who exhibits signs of osteoarthritis, the method comprising: a) obtaining a sample from the subject; b) measuring in the sample the production of transcription or translation products produced by the expression of one or more OA-associated genes or gene fragments comprising any of SEQ ID NOS: 1-1558, or fragments thereof; c) comparing the transcription or translation products of the sample with that of a standard, wherein a difference in the expression of any of the OA-associated genes or gene fragments is indicative of osteoarthritis.

18. A kit for detecting the presence of osteoarthritis or predisposition for osteoarthritis in a subject comprising one or more oligonucleotides of at least about 10 consecutive nucleotides of a sequence selected from sequences hybridizing to two or more genes or gene fragments comprising any of SEQ ID NOS: 1-1558, or fragments thereof, wherein the oligonucleotides specifically bind to nucleic acids differentially expressed in an osteoarthritic subject or in a subject predisposed to osteoarthritis compared to expression in subjects which are not osteoarthritic or predisposed to osteoarthritis.

19. A kit for assaying the expression of genes differentially expressed in osteoarthritis, comprising a container containing a collection of two or more probes, wherein the probes comprise one or/more of:

a) oligonucleotides or polynucleotides that specifically hybridize to two or more genes or gene fragments comprising any of SEQ ID NOS: 1-1558, or fragments thereof; or b) polypeptide binding agents that specifically bind to polypeptides produced by expression of two or more genes or gene fragments comprising any of SEQ ID NOS: 1-1558, or fragments thereof; \

and instructions for performing an assay of gene expression.

20. A method of modulating osteoarthritis-associated gene expression in a cell by administering an effective amount of a compound under appropriate conditions to affect the expression of at least one gene associated with osteoarthritis having a sequence selected from SEQ ID NOs:l- 1588, or fragments thereof.

21. A method of modulating osteoarthritis-associated gene expression in a cell by administering an effective amount of a compound under appropriate conditions to affect the expression of at least one gene associated with osteoarthritis having a gene product identified in Table 6.

23. The method of claim 21 or 22, wherein the compound is a vitamin, mineral, neutriceutical, small molecule pharmaceutical, protein, polypeptide, nucleic acid, fatty acid or polysaccharide.

24. The method of claim 23, wherein the compound is eicosopentaenoic acid, arachidonic acid, glucosamine, chondroitin sulfate, lα,25-dihydroxy vitamin D3, or 24R,25-dihydroxy vitamin D3.

25. A method for identifying compounds that modulate osteoarthritis-associated genes comprising: a) measuring standard expression by measuring transcription or translation products of one or more of the genes or gene fragments comprising any of SEQ ID NOS: 1-1558, or fragments thereof, in a standard sample in the absence of a test compound; b) measuring test expression by measuring the transcription or translation products of one or more of the genes or gene fragments comprising any of SEQ ID NOS: 1-1558, or fragments thereof, in a test sample in the presence of the test compound; and c) comparing the standard expression to the test expression, wherein a change in the test expression compared to the standard expression is indicative of an effect of the test compound on the expression of genes differentially expressed in osteoarthritis compared to a non-osteoarthritic condition.