Calcitonin gene-related peptide II, substance P and vasoactive intestinal peptide in plasma and synovial fluid from patients with inflammatory joint disease.

Immunoreactive plasma and synovial fluid concentrations of calcitonin gene-related peptide II (CGRP II), substance P and vasoactive intestinal peptide (VIP) were measured in patients with osteoarthritis, gout and rheumatoid arthritis. Significantly higher levels of CGRP II and substance P-like immunoreactivity levels in synovial fluid were found in gout as well as CGRP II, substance P and VIP-like immunoreactivities in rheumatoid arthritis when compared to those in osteoarthritis. Plasma CGRP II, substance P and VIP-like immunoreactivity levels showed no significant differences among patients in the three different groups of arthritis. Our results suggest that these neuropeptides released from peripheral nerve endings into the synovial cavity probably play a pathogenic role in human joint inflammation.