NGF is enriched in the synovial (89, 90) and osteochondral junctions of patients with RA and exerts its proinflammatory effects through a variety of mechanisms, including mast-cell sensitization and an increase in the synthesis and release of neuropeptides (CGRP and SP), which lead to vasodilation and plasma extravasation, triggering painful behavior (91). This evidence concerns the gene NGF and rheumatoid arthritis.