Hee-Jeong Im, Xin Li, Muddasani, Prasuna, Gun-Hee Kim, Davis, Francesca, Rangan, Jayanthi, Forsyth, Christopher B., Ellman, Michael, and Thonar, Eugene J. M. A.
Pain-related neuropeptides released from synovial fibroblasts, such as substance P, have been implicated in joint destruction. Substance P-induced inflammatory processes are mediated via signaling through a G-protein-coupled receptor, that is, neurokinin-1 tachykinin receptor (NK1-R). We determined the pathophysiological link between substance P and its receptor in human adult articular cartilage homeostasis. We further examined if catabolic growth factors such as basic fibroblast growth factor (bFGF or FGF-2) or IL-1β accelerate matrix degradation via a neural pathway upregulation of substance P and NK1-R. We show here that substance P stimulates the production of cartilage-degrading enzymes, such as matrix metalloproteinase-13 (MMP-13), and suppresses proteoglycan deposition in human adult articular chondrocytes via NK1-R. Furthermore, we have demonstrated that substance P negates proteoglycan stimulation promoted by bone morphogenetic protein-7, suggesting the dual role of substance P as both a pro-catabolic and anti-anabolic mediator of cartilage homeostasis. We report that bFGF-mediated stimulation of substance P and its receptor NK1-R is, in part, through an IL-1β-dependent pathway. J. Cell. Physiol. 215: 452–463, 2008. © 2007 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]