DEGRADATION OF ENDOTHELIAL-CELL MATRIX HEPARAN-SULFATE PROTEOGLYCAN BY ELASTASE AND THE MYELOPEROXIDASE-H2O2-CHLORIDE SYSTEM

The degradation of the heparan sulfate proteoglycans of subendothelial matrix by neutrophil elastase and the myeloperoxidase-H2O2-chloride s ystem added separately, sequentially, or together at pH 4.5 to 7.5 was determined by the release of lower molecular weight S-35-labeled mate rial Elastase alone and the myeloperoxidase system alone caused degrad ation, and when 4-hour exposure to elastase was followed by 15 minutes of exposure to the myeloperoxidase system, the effect was greater tha n additive. A greater than additive effect was not observed when elast ase followed the myeloperoxidase system or the two were added together . Chloride (or sulfate) alone increased the release of S-35-labeled ma terial from elastase-treated matrix, although the effect of 0.1 M chlo ride was not as great as that observed when an equivalent concentratio n of chloride was combined with myeloperoxidase and H2O2. The release of these systems at sites of adherence of neutrophils to glomerular ba sement membrane may contribute to neutrophil-associated proteinuria.