Fibroblast biology - Effector signals released by the synovial fibroblast in arthritis

There is mounting evidence indicating that the synovial fibroblast is a dir ect effector of tissue injury and matrix remodeling in inflammatory synovit is. Through the elaboration of effector signals including cytokines and che mokines, mesenchymal cells stimulate or suppress inflammation via autocrine and paracrine mechanisms. Synovial fibroblasts are the principal cells med iating joint destruction through secretion of metalloproteinases, and recen t evidence suggests that they may also promote bone resorption by stimulati ng osteoclastogenesis. Moreover, they may play an integral role in the init ial phases of synovitis by releasing chemokines that recruit leukocytes to the joint, and cytokines that trigger angiogenesis. Studies focusing on syn oviocyte-leukocyte interactions mediated via the cytokine network and the r ole of cell-cell contact in driving synoviocyte activation will help define the complex interplay that leads to the initiation and perpetuation of syn ovial inflammation.