LOW-INTENSITY PULSED ULTRASOUND AFFECTS CHONDROCYTE EXTRACELLULAR MATRIX PRODUCTION VIA AN INTEGRIN-MEDIATED P38 MAPK SIGNALING PATHWAY

Abstract Although low-intensity pulsed ultrasound (LIPUS) regulates p38 mitogen-activated protein kinase (MAPK) and promotes cartilage repair in osteoarthritis, the role of integrin-mediated p38 MAPK in the effect of LIPUS on extracellular matrix (ECM) production of normal and OA chondrocytes remains unknown. The aim of this study was to investigate whether LIPUS affects ECM production in normal and OA rabbit chondrocytes through an integrin–p38 signaling pathway. A rabbit model of OA was established by anterior cruciate ligament transection, and chondrocytes were isolated from normal or OA cartilage and cultured in vitro . Chondrocytes were treated with LIPUS and then pre-incubated with the integrin inhibitor GRGDSP or the p38 inhibitor SB203580. Expression of type II collagen, MMP-13, integrin β1, p38 and phosphorylated p38 was assessed by Western blot analysis. We found that type II collagen and integrin β1 were upregulated ( p p p p