Degradation of cartilage proteoglycan by human leukocyte granule neutral proteases--a model of joint injury. I. Penetration of enzyme into rabbit articular cartilage and release of 35SO4-labeled material from the tissue

J Clin Invest. 1976 Mar;57(3):615-24. doi: 10.1172/JCI108317.


The present work was undertaken to explore the effect of two purified neutral proteases derived from human peripheral blood polymorphonuclear leukocytes (PMN) on articular cartilage as a model of joint injury. Human leukocyte elastase and chymotrypsin-like enzyme, purified by affinity chromatography, released 32SO4 from labeled rabbit articular cartilage slices in vitro. Release of isotope was initially delayed, suggesting that either a lag in enzyme penetration occurs or that size of degradation fragments is a limiting factor in diffusion of label out of the tissue. The release of 35SO4 was inhibited by preincubation of elastase and chymotrypsin-like enzyme with human alpha 1-anti-trypsin, or with their specific chloromethyl ketone inactivators, and the action of elastase was also inhibited by a monospecific antiserum to PMN elastase, freed of major serum proteinase inhibitors. Immunohistochemical staining procedures revealed the presence of PMN elastase inside the matrix of cartilage slices after a 20-min exposure of tissue to either the pure enzyme or crude PMN granule extract. Serum alpha 1-antitrypsin failed to penetrate into the cartilage slices under identical in vitro conditions. In association with the results reported in the accompanying paper, these findings suggest a model of cartilage matrix degradation by PMN neutral proteases in which local protease-antiprotease imbalance, coupled with different rates of penetration of protease and antiprotease into target tissue, plays a key role in accounting for matrix damage.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Cartilage, Articular / drug effects
  • Cartilage, Articular / metabolism*
  • Chymotrypsin / isolation & purification
  • Chymotrypsin / pharmacology
  • Cytoplasmic Granules / metabolism*
  • Disease Models, Animal*
  • Enzyme Inhibitors / pharmacology
  • Glycosaminoglycans / metabolism*
  • Humans
  • Immune Sera
  • Joint Diseases / metabolism*
  • Kinetics
  • Leukocytes / enzymology
  • Leukocytes / ultrastructure*
  • Oligopeptides / pharmacology
  • Pancreatic Elastase / isolation & purification
  • Pancreatic Elastase / pharmacology
  • Peptide Hydrolases / metabolism*
  • Phenylalanine / analogs & derivatives
  • Proteoglycans / metabolism*
  • Rabbits
  • Sulfur Radioisotopes
  • alpha 1-Antitrypsin / metabolism
  • alpha 1-Antitrypsin / pharmacology


  • Enzyme Inhibitors
  • Glycosaminoglycans
  • Immune Sera
  • Oligopeptides
  • Proteoglycans
  • Sulfur Radioisotopes
  • alpha 1-Antitrypsin
  • Phenylalanine
  • Peptide Hydrolases
  • Chymotrypsin
  • Pancreatic Elastase