Expression of metalloproteinases and their inhibitors in degenerated and extruded intervertebral disks in chondrodystrophic dogs

We analyzed the mRNA expression of matrix metalloproteinases (MMPs), metalloproteinases with thrombospondin motifs (ADAMTSs), and tissue inhibitors of metalloproteinases (TIMPs) in degenerated and herniated intervertebral disks (IVDs) in chondrodystrophic dogs. In degenerated IVDs, MMP3, 7, 13, and 14; ADAMTS4 and 5; and TIMP1–3 expression was significantly higher vs healthy controls (P<0.05). In herniated IVDs, MMP2, 3, 9, 13, and 14; ADAMTS4 and 5; and TIMP1 expression was significantly greater, and MMP7 expression was significantly lower vs degenerated IVDs (P<0.05). These results suggest that metalloproteinase may play a role in extracellular matrix degradation in IVD degeneration. Decreased MMP7 transcription may prevent proteoglycan degradation and reduces macrophage infiltration, which might affect the resorption process of herniated IVDs.