VIP decreases TLR4 expression induced by LPS and TNF-alpha treatment in human synovial fibroblasts.

It has been demonstrated that VIP produces beneficial effects both in a murine model of rheumatoid arthritis and in human rheumatoid synovial fibroblasts through the modulation of proinflammatory mediators. Toll-like receptors (TLRs) play a key role in the immediate recognition of microbial surface components by immune cells prior to the development of adaptative microbe-specific immune responses. In this study, we demonstrate that VIP decreases lipopolysaccharide (LPS) and TNF-alpha-induced expression of TLR4 and its correlation with the production of CCL2 and CXCL8 chemokines in human synovial fibroblasts from patients with rheumatoid arthritis and osteoarthritis. Our results add a new step for the use of VIP, as a promising candidate, for the treatment of rheumatoid arthritis.