Collagenolytic enzyme systems in human intervertebral disc: their control, mechanism, and their possible role in the initiation of biomechanical failure.

Changes in the macromolecular matrix of the intervertebral disc may predispose to biomechanical failure of the disc. Such changes would involve extracellular enzymes capable of altering the collagen and proteoglycan of the disc matrix. In this study, extracts from homogenates of both annuli fibrosi and nuclei pulposi of human lumbar discs were found to contain neutral collagenolytic, gelatinolytic, and elastinolytic enzymes in all samples assayed. The specific activity of the collagenase was higher in extracts from nuclear than from annular tissue, a difference not seen with gelatinase or elastase. The collagenase was present as both a latent and active enzyme, the other enzymes being fully active. Human intervertebral discs therefore contain enzymes capable of degrading their extracellular macromolecular matrix.