TRPV1 and Arthritis: Secondly, increased TRPV1 expression in both mRNA and protein levels was observed in synovial fibroblasts [17] and chondrocytes [18] from patients with arthritis, and TRPV1 activation has been shown to upregulate the expression of pro-inflammatory cytokines (IL-1β, IL-6, TNF-α) [16,17] and to be involved in the generation of ROS [19,20].