Expression of MMP-1,MMP-13 and ERK1/2 in joint cartilage of an osteoarthritis rabbit model

Objective To detect protein expression of matrix metalloproteinase-1 (MMP-1), matrix metalloproteinase-13(MMP-13)and extracellular regulated kinase 1/2(ERK1/2) in the joint cartilage of osteoarthritic rabbit knee at different time points after ACLT and partial excision of the medial meniscus. Methods Thirty rabbits in the experimental group received unilateral ACLT and partial excision of the medial meniscus, and another 10 rabbits received unilateral arthrotomy as pseudo-operation control. Ten of the 30 experimental rabbits were sacrificed at week 4, 8 and 12 after surgery respectively, and 10 pseudo-operation rabbits were sacrificed at 12 weeks after surgery. The knees were harvested to observe macropathologic changes of the joint cartilage. MMP-1, MMP-13 and ERK1/2 proteins near the cartilage lesions were detected by Western Blot. Results Cartilage degeneration was obvious at week 4 and became more severe at week 8 and 12 after operation, while the cartilage remained normal at week 12 after pseudo-operation. The expression of MMP-1, MMP-13 and ERK1/2 protein was constantly low in the normal cartilage of the pseudo-operation group. In the experimental group, the expression of MMP-1 and ERK1/2 protein began increasing at week 4, and remained at a high level at week 8 and 12 after operation, while the expression of MMP-13 protein began increasing at week 4, remained increased at week 8, and began decreasing at week 12. Conclusions MMP-1 and MMP-13, especially MMP-1, seem to be good markers for study of osteoarthritis. MMP-13 expression was different from MMP-1 expression at week 12 after operation, suggesting that their upstream signaling pathways may be different. The ERK1/2 signal transduction pathway seems to play a constant role in the pathogenesis of osteoarthritis.