CNR1 and rheumatoid arthritis: This effect was mediated by transient receptor potential cation channel (TRP) subfamily V1 (TRPV1) and TRP subfamily A1 (TRPA1), not CB1 and CB2.44 A follow-up study showed that CBD also reduces the secretion of IL-6, IL-8, and MMP3 from synovial fibroblasts from RA patients.