Effects of MMP-1 and MMP-3 gene polymorphisms on gene expression and protein level in lumbar disc herniation

The aim of this study was to identify the possible correlation between polymorphisms in matrix metalloproteinase (MMP)-1 and MMP-3 and their corresponding protein levels in disc tissues obtained from patients with lumbar disc herniation (LDH) using biochemical and immunohistochemical analyses. Blood and disc samples were obtained from 100 patients with LDH who underwent a lumbar microdiscectomy. Based on the radiological degeneration, the patients were diagnosed with grade 2, 3, or 4 LDH. MMP-1 -1607 1G/2G and MMP-3 -1171 5A/6A were analyzed by real-time polymerase chain reaction. The expressions of MMP-1 and MMP- 3 were detected by biochemical and immunohistochemical analyses. We found no association between the MMP-1 polymorphism and disc degeneration and MMP-1 expression. However, patients expressing the 6A/6A and 5A/6A alleles of MMP-3 -11715A/6A showed higher MMP-3 expression, compared to those expressing the 5A/5A genotype. Additionally, the radiological degeneration grades were correlated with the histological degeneration scoring. Protein levels and immunopositive cell rates of MMP-1 and MMP-3 were associated with disc degeneration grades. Moreover, the MMP-1 and MMP-3 expression and the histological and radiological scores were positively correlated and the MMP-3 -11715A/6A polymorphism was associated with MMP-3 expression in herniated disc tissues. This study is the first to investigate polymorphisms in MMP-1 and MMP-3, as well as their corresponding protein expressions. We also quantified an association between the radiological degeneration grades and MMP-1 and MMP- 3 expression. Further genomic studies on MMPs could focus on the utilization of MMP-1 and MMP-3 as markers for the prevention and treatment of this disease.