title: Heparin antagonists are potent inhibitors of mast cell tryptase.
abstract: Tryptase may be a key mediator in mast cell-mediated inflammatory reactions. When mast cells are activated, they release large amounts of these tetrameric trypsin-like serine proteases. Tryptase is present in a macromolecular complex with heparin proteoglycan where the interaction with heparin is known to be essential for maintaining enzymatic activity. Recent investigations have shown that tryptase has potent proinflammatory activity, and inhibitors of tryptase have been shown to modulate allergic reactions in vivo. Many of the tryptase inhibitors investigated previously are directed against the active site. In the present study we have investigated an alternative approach for tryptase regulation. We show that the heparin antagonists Polybrene and protamine are potent inhibitors of both human lung tryptase and of recombinant mouse tryptase (mouse mast cell protease 6). Protamine inhibited tryptase in a competitive manner whereas Polybrene showed noncompetitive inhibition kinetics. Treatment of tetrameric, active tryptase with Polybrene caused dissociation into monomers, accompanied by complete loss of enzymatic activity. The present report thus suggests that heparin antagonists potentially may be used in treatment of mast cell-mediated diseases such as asthma.
authors.affiliation: Department of Veterinary Medical Chemistry, The Biomedical Center, Swedish University of Agricultural Sciences, Box 575, 751 23 Uppsala, Sweden.
authors.forename: J
authors.initials: J
authors.lastname: Hallgren
authors.forename: S
authors.initials: S
authors.lastname: Estrada
authors.forename: U
authors.initials: U
authors.lastname: Karlson
authors.forename: K
authors.initials: K
authors.lastname: Alving
authors.forename: G
authors.initials: G
authors.lastname: Pejler
mesh_terms: D000818:Animals; D002460:Cell Line; D004151:Dipeptides / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation / Q000187:drug effects / Q000235:genetics; D006493:Heparin / Q000378:metabolism; D006494:Heparin Antagonists / Q000494:pharmacology*; D006583:Hexadimethrine Bromide / Q000494:pharmacology; D006801:Humans; D007781:Lactoferrin / Q000494:pharmacology; D008407:Mast Cells / Q000201:enzymology*; D051379:Mice; D011479:Protamines / Q000494:pharmacology; D012697:Serine Endopeptidases / Q000235:genetics / Q000378:metabolism*; D015842:Serine Proteinase Inhibitors / Q000494:pharmacology*; D014162:Transfection; D053802:Tryptases
chemical_list: D004151:Dipeptides; D006494:Heparin Antagonists; C094700:N-(1-hydroxy-2-naphthoyl)arginyl-prolinamide; D011479:Protamines; D015842:Serine Proteinase Inhibitors; C509190:Tpsb2 protein, mouse; D006583:Hexadimethrine Bromide; D006493:Heparin; D007781:Lactoferrin; D012697:Serine Endopeptidases; C509222:Tpsab1 protein, mouse; D053802:Tryptases