title: Sputum sol neutrophil elastase activity in bronchiectasis: differential modulation by syndecan-1.
abstract: The persistently dominant activity of neutrophil elastase in bronchial secretions replete with antielastases is crucial to the pathogenesis of bronchiectasis. We hypothesize that components in the bronchial secretions bind neutrophil elastase and compromise the inhibitory efficiency of prevailing antielastases. Zymographic analysis of sputum sols from patients with bronchiectasis found elastase activity in a polydisperse, alcian blue-stained zone of high molecular mass. This suggested that neutrophil elastase was complexed with polyanionic partners. Western blot analysis found not only the polyanionic partner, heparan sulfate/syndecan-1, but also the physiological antielastases, secretory leukoproteinase inhibitor and alpha1-antitrypsin, in the complex. Both dissociative density gradient ultracentrifugation and heparin displacement revealed that elastase dissociated from heparan sulfate/syndecan-1 was fully inhibited by the endogenous antielastases. This contrasts with the effects of exogenous antielastases on sputum neutrophil elastase activity-that of alpha1-antitrypsin was limited, but that of secretory leukoproteinase inhibitor was facilitated. Similarly, complexed elastase on blots of sputum sol zymographs was bound and inhibited by exogenous secretory leukoproteinase inhibitor but not by exogenous alpha1-antitrypsin. Taken together, the results bring a new focus to heparan sulfate/syndecan-1 complexed with neutrophil elastase in inflamed bronchial secretions as a target for modulating elastase susceptibility to physiological antielastases.
authors.affiliation: Department of Biochemistry, University of Hong Kong, 21 Sassoon Road, Hong Kong, China. shumdkhk@hkucc.hku.hk
authors.forename: Stanley C H
authors.initials: SC
authors.lastname: Chan
authors.forename: Daisy K Y
authors.initials: DK
authors.lastname: Shum
authors.forename: Mary S M
authors.initials: MS
authors.lastname: Ip
mesh_terms: D015153:Blotting, Western; D001987:Bronchiectasis / Q000201:enzymology*; D005260:Female; D006497:Heparan Sulfate / Q000378:metabolism; D006801:Humans; D019272:Leukocyte Elastase / Q000378:metabolism*; D008297:Male; D008562:Membrane Glycoproteins / Q000378:metabolism; D008875:Middle Aged; D053491:Proteinase Inhibitory Proteins, Secretory; D011506:Proteins / Q000378:metabolism; D011509:Proteoglycans / Q000378:metabolism; D015842:Serine Proteinase Inhibitors / Q000378:metabolism; D013183:Sputum / Q000201:enzymology*; D053668:Syndecan-1; D053667:Syndecans; D000515:alpha 1-Antitrypsin / Q000378:metabolism
chemical_list: D006497:Heparan Sulfate; D019272:Leukocyte Elastase; D008562:Membrane Glycoproteins; D053491:Proteinase Inhibitory Proteins, Secretory; D011506:Proteins; D011509:Proteoglycans; D015842:Serine Proteinase Inhibitors; D053668:Syndecan-1; D053667:Syndecans; D000515:alpha 1-Antitrypsin; C508241:SDC1 protein, human