Synovial biomarkers in the spondylarthropathies.

Purpose of the review To explore the concept of a biomarker, or surrogate endpoint, to enhance early diagnosis or predict the response to therapeutic intervention in patients with spondylarthropathy. Recent findings Immunopathologic studies have suggested that the features of spondylarthropathy are distinctive, supporting a prominent role for innate immune cells, and can be consistently differentiated from rheumatoid arthritis. Successful treatment of spondylarthropathy synovitis resulted in rapid and sustained decrease in infiltration by macrophage populations and neutrophils, and decreased expression of many proinflammatory mediators. Consistent with studies in rheumatoid arthritis, significant correlations between the effects of both methotrexate and infliximab on disease activity and sublining macrophage populations were reported. These observations highlight the possibility that macrophage populations may be a synovial tissue biomarker of therapeutic intervention in spondylarthropathy. Preliminary studies have evaluated advanced genomic and proteomic methodologies in spondylarthropathy. Defining the immunopathology of spondylarthropathy has been associated with identifying potential biomarkers of the clinical response to therapeutic intervention. A surrogate marker of arthritis activity in spondylarthropathy could profoundly enhance screening for efficacy and optimization of dose ranges in early-phase randomized clinical trials.