THE INVOLVEMENT OF MATRIX METALLOPROTEINASES AND INFLAMMATION IN LUMBAR DISC HERNIATION

Study Design. Surgically obtained herniated lumbar disc specimens were stained with hematoxylin-eosin or toluidine blue (for detection of pr oteoglycans) or were immunostained with monoclonal antibodies (CD68), antihuman interstitial collagenase (matrix metalloproteinase [MMP]-1) and antihuman stromelysin (MMP-3). Objective. To investigate the possi ble correlation of matrix metalloproteinase activity to granulation ti ssue formation and lumbar disc herniation, depending on the type of he rniation. Summary of Background Data. Interstitial collagenase and str omelysin have been implicated in the degradation of the matrix of arti cular cartilage in rheumatoid arthritis, osteoarthritis and degenerate d disc tissues. However, their role in the herniation of the intervert ebral disc has received little study. Methods. Twenty-one specimens of lumbar disc herniation (classified as protrusions, subligamentous ext rusions, transligamentous extrusions, and sequestrations) and four non herniated discs were stained with hematoxylin-eosin or toluidine blue or were immunostained with monoclonal antibodies to CD20, CD45RO, and CD68, anti-MMP-1, and anti-MMP-3, using the avidin-biotin-peroxidase c omplex method. The amount of granulation tissue and results of stainin g were graded to examine differences in histology among the four herni ation types. Results. In sequestration and transligamentous extrusion specimens, granulation tissue containing many CD68-positive macrophage s was commonly observed. Most cells in granulation tissue, as well as chondrocytes, stained positively with anti-MMP-1 and anti-MMP-3 antibo dies. Granulation tissue was less commonly observed in subligamentous extrusions and was absent from most protrusion specimens and all nonhe rniated specimens. B and T lymphocytes could not be demonstrated in gr anulation tissue. Conclusions. The increased staining of MMP-1 and MMP -3 associated with inflammatory cells of granulation tissue in herniat ed discs suggests a causal correlation of these proteinases to tissue degradation in herniation.