Abnormal connective tissue degrading enzyme patterns in prolapsed intervertebral discs.

Abstract

The collagenolytic enzyme systems in the human, normal, and prolapsed intervertebral discs have been studied. Normal discs obtained postmortem contained a novel collagenase with specificity toward Type II collagen and gelatin but with little or no activity against Type I collagen. A method whereby enzymes are detected quantitatively in extracts of human tissue using specific substrates, without prior chromatographic separation of the enzymes, has been developed and used to study 14 normal discs and 35 surgically excised prolapsed discs. No differences were observed between annulus and nucleus extracts of normal discs either in the pattern of enzymes or the quantity. The intermediate zone between nucleus and annulus was excised and was not tested. Highly significant differences were observed between the enzyme patterns of the normal and prolapsed discs. The major collagenolytic activity of normal discs is against Type II collagen and 1 alpha 2 alpha 3 alpha collagen, there is little activity toward Type I collagen and virtually none toward elastin. Conversely, the prolapsed disc is more highly active against the substrates elastin and Type I collagen than against Type II collagen or 1 alpha 2 alpha 3 alpha collagen. The individual patterns of enzymes of the 35 prolapsed discs were virtually identical. Similarly there was little internal variation between the patterns of enzymes extracted from discs, obtained postmortem, which were apparently normal. The striking difference between the normal and prolapsed disc could be an important factor in the pathogenesis of disc prolapse.