Synovial and serum levels of NGF in osteoarthritis and rheumatic diseases: a systematic review.

NGF has raised interest as a target molecule in the treatment of OA, after the clinical evidences that antagonization of NGF axis provides symptoms relief in OA. Thus, we conducted a systematic review of the literature to investigate the evidence of NGF being overexpressed during OA. We conducted a database search on Medline using keywords including NGF, serum, synovial fluid, AND osteoarthritis or arthritis. We included study conducted on human, with serum or synovial specimens and an OA cohort. Nine studies met the inclusion criteria. Serum levels ranged from non-detectable to 153.5±28.6 pg/ml. Synovial fluid levels ranged from non-detectable to nearly 210±82 pg/ml. One study supported the evidence of an increased level of NGF in SF and serum of OA patients. The concentration of NGF reported in these studies is controversial and evidence of overexpression of NGF is low.