Matrix metalloproteinases in the human intervertebral disc: Role in disc degeneration and scoliosis

Study Design. Biochemical study of human intervertebral discs collected at surgery from patients with low back pain associated with disc degeneration or scoliosis. Matrix metalloproteinases were studied by quantitative zymography. Objective. To determine whether changes in the expression of matrix metalloproteinases wilt bring about tissue remodelling that contributes to the progressive nature and pathology of these diseases of the intervertebral disc. Summary of Background Data. The diseases of the intervertebral disc, degenerative disc disease and scoliosis, are both characterized by changes in the extracellular matrix components that will affect the mechanical function of the tissue. Matrix metalloproteinases are known to have the capability of degrading all the known extracellular matrix components of the disc. Methods. Matrix metalloproteinases 2 and 9 were detected by gelatin-gel zymography and quantified by laser scanning densitometry. Both pro and active forms of the enzymes were measured. Thirty-four discs from patients with low back pain and 29 from patients with scoliosis were investigated. Results. A correlation was found between the increasing levels of matrix metalloproteinases 2 and 9 and the grade of degenerative disc disease. In addition, the levels of these enzymes show a differential expression across the scoliotic disc with the highest levels in samples taken from the convexity of the curve. Conclusions. The difference between the concave and convex side of the scoliotic curve indicates that mechanical loads might influence the expression of these enzymes. The increased expression of these enzymes in both degenerative disc disease and scoliosis strongly suggests that they may affect the progressive nature of these diseases.