[Psoriatic synovitis: pathogenic and therapeutic implications]

Psoriatic arthritis (PsA) is a chronic inflammatory autoimmune disease characterized by arthritis and psoriasis of the skin. It is classified within the spondyloarthropathies (SpA) group. The wide clinical heterogeneity of PsA has hampered research into its pathogenesis and the performance of large randomized clinical trials with disease-modifying anti-rheumatic drugs. The success of biologic agents in PsA has stimulated wide interest in this disease as well as in its clinical classification and underlying pathogenic mechanisms. Several recent articles on the pathogenesis of PsA are reviewed, focussing on the potential of synovial angiogenesis as a therapeutic target and on synovial expression of macrophages and p53 protein related to joint damage in rheumatoid arthritis (RA) and PsA. Finally, the question of whether the polyarticular variant of PsA shares immunohistochemical features with RA or SpA is also discussed. Although the success of tumor necrosis factor-alpha antagonists in both RA and PsA supports a similar pathogenesis in both disorders, these and other studies suggest that there are differences in the synovial expression and pathogenic significance of certain cells and molecules. If confirmed, this phenomenon could open new avenues in specific therapy for PsA.