NGF and rheumatoid arthritis: For instance, it is yet to be demonstrated whether human synovial fibroblasts from patients with RA release NGF—and whether they continue to do so in the many individuals who continue to experience pain in the absence of synovitis.62 We also know nothing about whether known fibroblast subpopulations in joint,28 skin63 or other tissues64 differentially affect nociceptor sensitisation.