Effect of Low-Intensity Pulsed Ultrasound on MMP-13 and MAPKs Signaling Pathway in Rabbit Knee Osteoarthritis

We evaluated the effect of low-intensity pulsed ultrasound (LIPUS) on MMP-13 and MAPKs expression in rabbit knee osteoarthritis (OA). For this purpose, 18 New Zealand white rabbits were randomly and equally divided into O + L, O - L, and SO groups. In O + L group, animals underwent right back leg ACLT operation and LIPUS radiation. In O - L group, animals underwent ACLT but no LIPUS treatment. In SO (control) group, animals underwent sham operation without LIPUS. After 6 weeks, we assessed the pathologic changes in the articular surface of femoral condyle and compared using Mankin scores. Also, expression of type-II collagen, MMP-13, ERK1/2, p38, and JNK was measured by Western blot. Compared with controls, Mankin scores were higher in O + L (P < 0.05)/O - L (P < 0.01) groups. Compared with O + L group, score was higher in O - L group (P < 0.05). Compared with controls, type-II collagen expression was less in O + L/O - L groups, with more significant decrease in O - L group (P < 0.05). Contrarily, expression of MMP-13, p-ERK1/2, and p-p38 was enhanced in O + L/O - L groups as compared with controls, with more significant increase in O - L group (P < 0.01). Compared with O + L group, expression was higher in O - L group (P < 0.05). We, therefore, concluded that LIPUS application promoted cartilage repair in OA through the downregulation of MMP-13, ERK1/2, and p38.