Spingosine-1-phosphate stimulates proliferation and counteracts interleukin-1 induced nitric oxide formation in articular chondrocytes

Objective: Sphingosine-1-phosphate (S1P) is a messenger molecule, with important functions in inflammation and wound healing. The present study was performed to elucidate a possible role of S1P signaling in articular chondrocytes. Methods: Human and bovine primary chondrocytes were cultured in monolayer. Reverse transcriptase polymerase chain reaction (RT-PCR) was performed to detect S1P receptor mRNA. Proliferation of S1P stimulated chondrocytes was measured by H-3-thymidine uptake. Supernatants of cultured bovine chondrocytes stimulated with S1P alone or in combination with interleukin-1 beta (IL-1 beta) were tested for nitric oxide (NO) formation and expression of inducible nitric oxide synthase (iNOS). Matrixmetalloprotease-13 (MMP-13) and aggrecanase-1 (ADAMTS-4) were evaluated using real-time PCR. Glycosaminoglycan (GAG) loss from bovine cartilage explants was evaluated using the dimethylene blue method. Results: S1P(1), S1P(2) and S1P(3) but not S1P(4) and S1P(5) receptor mRNA were detected in human and bovine chondrocytes. S1P dose dependently induced proliferation in bovine and human chondrocytes. S1P significantly reduced NO formation and iNOS mRNA and protein expression, both in un-stimulated and IL-1 beta stimulated bovine chondrocytes. Furthermore, S1P dose dependently inhibited IL-1 beta induced expression of ADAMTS-4 and MMP-13 and diminished IL-1 beta mediated GAG depletion from cartilage explants. Conclusion: These results suggest that S1P provides an anti-catabolic signal in articular chondrocytes. (C) 2007 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.