Correlation of matrix metalloproteinases–1 and –3 with patient age and grade of lumbar disc herniation

Abstract

The authors studied the histological alterations and the expression of matrix metalloproteinase (MMP)-1 and MMP-3 in disc specimens of patients who had undergone operations for lumbar disc herniation. Forty-three lumbar disc specimens were evaluated histopathologically for degenerative changes and immunohistochemical expression of MMP-1 and MMP-3. The observed degenerative changes provided a degenerative score that was applied in each patient. Sections of disc immunostained for MMP-1 and MMP-3 were evaluated semiquantitatively. Patients were categorized in 3 age groups: < 30 years, between 30 and 60 years, and > 60 years of age. The expression of MMP-1 and MMP-3 were correlated to patient's age, degenerative score, and grade of lumbar disc herniation. There was no statistically significant difference in the degenerative score between the age groups. Degenerative changes were more pronounced in greater grades of herniation (p < 0.0001). In the group of patients < 30 years of age there was a significant correlation between MMP-1 and MMP-3 expression and both degenerative score and herniation grade. For the group of patients 30-60 years of age, there was no significant difference between MMP-1 expression and degenerative score, but the correlation between MMP-1 expression and grade of herniation was significant. There was a significant correlation between MMP-3 expression and both degenerative score and herniation grade. Regarding the patients > 60 years of age, there was a significant correlation between MMP-1 and MMP-3 expression and both degenerative score and herniation grade. There was a significantly lower expression of both MMP-1 and MMP-3 in the group < 30 years of age compared with the other ages. No significant correlation was found in MMP-1 and MMP-3 expression between the groups of patients who were 30-60 and > 60 years of age. Interestingly, in age groups > 30 years, there were no statistically significant differences between the expression of MMP-1 and MMP-3, whereas in patients < 30 years of age the expression of MMP-3 was significantly lower than the expression of MMP-1. The expression of MMP-1 and MMP-3 were strongly correlated to the age of the patients and the grade of herniation. An important finding in this study is the differential expression of MMP-1 and MMP-3 between the age groups. In the young age group it appears that deregulation of MMP-1 expression is higher than that of MMP-3 in the pathogenesis of lumbar disc herniation.