Furthermore, CGRP alongside various molecules, such as bradykinin and prostaglandins as well as a multitude of proinflammatory cytokines (interleukins 1, 6, 17, nerve growth factor beta (NGF-β), and tumor necrosis factor alpha (TNF-α)), which directly alter the responses of nociceptive neurons, have been found abundantly in the synovial fluid of RA patients. Here, NGF is linked to rheumatoid arthritis.