Object: 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.
Methods: 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.
Results: 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.
Conclusions: 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.