Methods and Kits for the Diagnosis of Rheumatoid Arthritis

Abstract

The present invention relates to the identification and use of proteins with clinical relevance to rheumatoid arthritis (RA). In particular, the invention provides the identity of marker proteins that specifically react with RA-associated autoantibodies. Also provided are methods, arrays and kits for using these proteins in the diagnosis of RA, and in the selection and/or monitoring of treatment regimens.

1 . A method for the in vitro diagnosis of rheumatoid arthritis in a subject, said method comprising steps of:
 providing an autoantigen marker comprising BRAF catalytic domain, or an antibody-binding fragment thereof;   contacting a biological sample obtained from the subject with the autoantigen marker for a time and under conditions allowing an antigen-antibody complex to form; and   detecting the presence or absence of any antigen-antibody complex formed,   wherein the presence of an antigen-antibody complex is indicative of rheumatoid arthritis in the subject.   
     
     
         2 . The method of  claim 1 , wherein the subject is CCP-negative. 
     
     
         3 . The method of  claim 1 , wherein the biological sample is selected from the group consisting of whole blood, serum, plasma, urine, and synovial fluid. 
     
     
         4 . The method of  claim 1 , wherein the autoantigen marker is immobilized on a solid carrier or support. 
     
     
         5 . The method of  claim 1 , wherein detecting the presence or absence of an antigen-antibody complex is by immunoassay. 
     
     
         6 . The method of  claim 1 , wherein BRAF catalytic domain is of human origin. 
     
     
         7 . The method of  claim 6 , wherein BRAF catalytic domain has an amino acid sequence spanning from amino acid 416 to amino acid 766 of SEQ ID NO. 2. 
     
     
         8 . The method of  claim 1  further comprising detecting anti-PAD4 antibodies in a biological sample obtained from said subject. 
     
     
         9 . The method of  claim 1  further comprising measuring, in a biological sample obtained from said subject, the concentration of at least one marker selected from the group consisting of C-reactive protein, serum amyloid A, interleukin 6, S100 proteins, osteopontin, rheumatoid factor, matrix metalloprotease 1, matrix metalloprotease 3, hyaluronic acid, sCD14, angiogenesis markers, and products of bone, cartilage, or synovium metabolism. 
     
     
         10 . A kit for detecting anti-BRAF autoantibodies in a biological sample obtained from a subject, said kit comprising:
 an autoantigen marker comprising BRAF catalytic domain, or an antibody-binding fragment thereof; and   a reagent for detection of an antigen-antibody complex formed between the autoantigen marker and an autoantibody present in the biological sample, wherein the autoantibody is an anti-BRAF autoantibody that is indicative of rheumatoid arthritis.   
     
     
         11 . The kit of  claim 10 , wherein the autoantigen marker is immobilized on a solid carrier or support. 
     
     
         12 . The kit of  claim 10  further comprising instructions for carrying out the method according to  claim 1 . 
     
     
         13 . The kit of  claim 10  further comprising:
 a second autoantigen marker comprising PAD4, or an antibody-binding fragment thereof; and 
 a second reagent for detection of an antigen-antibody complex formed between the second autoantigen marker and an autoantibody present in the biological sample, wherein the autoantibody is an anti-PAD4 autoantibody that is indicative of rheumatoid arthritis. 
 
     
     
         14 . An array for diagnosing rheumatoid arthritis in a subject, said array comprising, attached to its surface:
 an autoantigen marker comprising BRAF catalytic domain, or an antibody-binding fragment thereof; and optionally,   a second autoantigen marker comprising PAD4 or an antibody-binding fragment thereof.   
     
     
         15 . The array of  claim 14  further comprising, attached to its surface, at least one additional autoantigen marker for detecting the presence of RA-specific autoantibodies in a biological sample, in particular antinuclear antibodies and anti-CCP antibodies. 
     
     
         16 . (canceled)