Integrin-mediated mechanotransduction in IL-1β stimulated chondrocytes

Mechanical loading and interleukin-1 beta (IL-1 beta) influence the release of nitric oxide (NO) and prostaglandin E-2 (PGE(2)) from articular chondrocytes via distinct signalling mechanisms. The exact nature of the interplay between the respective signalling pathways remains unclear. Recent studies have shown that integrins act as mechanoreceptors and may transduce extracellular stimuli into intracellular signals, thereby influencing cellular response. The current study demonstrates that the application of dynamic compression induced an inhibition of NO and an upregulation of cell proliferation and proteoglycan synthesis in the presence and absence of IL-1 beta. PGE(2) release was not affected by dynamic compression in the absence of IL-1 beta but was inhibited in the presence of the cytokine. The integrin binding peptide, GRGDSP, abolished or reversed the compression-induced alterations in all four parameters assessed in the presence and absence of IL-1 beta. The non-binding control peptide, GRADSP, had no effect. These data clearly demonstrate that the metabolic response of the chondrocytes to dynamic compression in the presence and absence of IL-1 beta, are integrin mediated.