Age-related expression of MCP-1 and MMP-3 in mouse intervertebral disc in relation to TWEAK and TNF-α stimulation

This study was undertaken to investigate the age-related differences of monocyte chemotactic protein-1 (MCP-1) and matrix metalloproteinase-3 (MMP-3) expression in mouse intervertebral disc (IVD) and to determine whether MMP-3 plays a role in disc degeneration. Expression of MCP-1 and MMP-3 mRNA in mouse IVD was assessed by quantitative PCR. The ability of MCP-1 and MMP-3 expression in IVD to respond to TNF-α or TWEAK stimulation was examined by quantitative PCR, WB, ELISA, and immunohistochemistry. IVD derived from MMP-3-deficient and wild-type mice were compared using Safranin-O staining and immunohistochemistry. mRNA levels of MCP-1 and MMP-3 in IVD significantly diminished and the ability of MCP-1 or MMP-3 expression to respond to TNF-α or TWEAK stimulation was significantly reduced as age increased. IVD derived from 64-week-old wild-type mice showed clearly diffuse proteoglycan loss by Safranin-O staining and immunohistochemistry compared with younger mice. However, no loss of proteoglycan and typeII collagen were observed in IVD derived from 64-week-old MMP-3-deficient mice. MCP-1 and MMP-3 expression in mouse IVD showed age-related decreases. The response to inflammation in IVD also displayed age-related changes. Therefore, disc degeneration may vary with the patients' age and targeting MMP-3 may be a possible future therapeutic strategy for disc degeneration.