Serological markers of erosive hand osteoarthritis.

This review focuses on biomarkers in erosive hand osteoarthritis (EHOA), a subset of hand osteoarthritis (HOA), that primarily affects interphalangeal joints and is characterized by abrupt onset, severe pain and functional impairment, as well as signs of inflammation, in particular stiffness, swelling, erythema, paraesthesiae, and worse outcome. Inflammatory features and radiographic erosions are the main diagnostic hallmarks of this particular disease subset. As in other fields of OA, EHOA biomarkers can be classified as dry and soluble. Soluble biomarkers which are found in serum, synovial fluid and urine can be specific indicators of joint inflammation and degradation. With regard to inflammatory markers, C-reactive protein and myeloperoxidase have been found to be increased in EHOA, with respect to non-erosive HOA. All these markers have, moreover, been found to be correlated with disease activity. Another interesting marker linked to inflammation is hyaluronic acid, considered to be a marker of synovitis, which is frequently found in EHOA. The most useful cartilage markers in both erosive and non-erosive HOA, seems to be collagen (Coll) 2-1, Coll 2-1NO(2) and Col2-3/4C(short). Immunogenetic markers were also determined and an association between EHOA and a single nucleotide polymorphism on the gene encoding interleukin-1β was found in HLA and there was an increased frequency of HLA-B44 and HLA-DRB1*07 in EHOA.