Heparin inhibits neutrophil-induced platelet activation via cathepsin G.
Activated human polymorphonuclear neutrophils (PMNs) induce platelet stimulation via cathepsin G (cat G), a platelet-activating cationic serine proteinase released from the azurophilic granules. Heparin inhibited up to 100% of aggregation and serotonin release triggered by 180 nmol/L of purified cat G in a concentration-dependent manner between 10 and 70 mU/ml. When tested against the enzymatic activity of 180 nmol/L cat G (hydrolysis of N-succinyl-Ala-Ala-Pro-Phe-p-nitroanilide), inhibition by heparin never exceeded 60% (up to 100 U/ml). Inhibition was most probably related to electrostatic interactions between the cationic cat G and the anionic heparin, because addition of 180 mU/ml of protamine sulfate restored platelet activation. Low molecular weight heparin, CY 216, used between 5 and 50 mU/ml, also inhibited cat G-induced platelet activation. When purified PMNs and washed platelets were mixed together and challenged with a PMN agonist (FMLP at 1 mumol/L), platelet activation was observed. Pretreatment of the mixed cell population with 300 mU/ml heparin prevented platelet activation. This was illustrated by electron microscopy studies. The present data, apart from confirming a participation of cat G in the PMN-platelet interaction, bring evidence that heparin has potent antiproteinase effect in a biologic model.
Ferrer-Lopez
P
P
Unité de Pharmacologie Cellulaire, Institut Pasteur, Paris, France.
Renesto
P
P
Prevost
M C
MC
Gounon
P
P
Chignard
M
M
D001792:Blood Platelets / Q000187:drug effects / Q000502:physiology / Q000648:ultrastructure; D056649:Cathepsin G; D002403:Cathepsins / Q000494:pharmacology* / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D006493:Heparin / Q000494:pharmacology*; D006801:Humans; D008854:Microscopy, Electron; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology; D009504:Neutrophils / Q000187:drug effects / Q000502:physiology* / Q000648:ultrastructure; D015539:Platelet Activation / Q000187:drug effects* / Q000502:physiology; D012697:Serine Endopeptidases
D009240:N-Formylmethionine Leucyl-Phenylalanine; D006493:Heparin; D002403:Cathepsins; D012697:Serine Endopeptidases; C534094:CTSG protein, human; D056649:Cathepsin G