Galectin-3: A key player in arthritis.

Arthritis is more and more considered as the leading reason for the disability in the world, particularly regarding its main entities, rheumatoid arthritis and osteoarthritis. The common feature of arthritis is inflammation, which is mainly supported by synovitis (synovial inflammation), although the immune system plays a primary role in rheumatoid arthritis and a secondary one in osteoarthritis. During the inflammatory phase of arthritis, many pro-inflammatory cytokines and mediators are secreted by infiltrating immune and resident joint cells, which are responsible for cartilage degradation and excessive bone remodeling. Amongst them, a β-galactoside-binding lectin, galectin-3, has been reported to be highly expressed and secreted by inflamed synovium of rheumatoid arthritis and osteoarthritis patients. Furthermore, galectin-3 has been demonstrated to induce joint swelling and osteoarthritis-like lesions after intra-articular injection in laboratory animals. However, the mechanisms underlying its pathophysiological role in arthritis have not been fully elucidated. This review deals with the characterization of arthritis features and galectin-3 and summarizes our current knowledge of the contribution of galectin-3 to joint tissue lesions in arthritis.