Enhancement of cathepsin G-induced platelet activation by leukocyte elastase: consequence for the neutrophil-mediated platelet activation.
We have focused our interest on the platelet-activating properties of two polymorphonuclear neutrophil (PMN)-derived proteinases, namely elastase (HLE) and cathepsin G (Cat.G). First of all, we observed that whereas HLE was unable to trigger platelet activation by itself, it enhanced platelet activation induced by Cat.G when both proteinases were added simultaneously. It has been recently described that, upon stimulation, PMN released Cat.G, which in turn activated surrounding platelets. Thus, we looked for a combined effect of Cat.G and HLE during this cell-to-cell interaction. When PMN (5 x 10(6)/mL) were stimulated by 0.5 mumol/L N-formyl-Met-Leu-Phe, they released 237.9 +/- 49.1 nmol/L Cat.G and 381.7 +/- 28.0 nmol/L HLE. Such a concentration of purified Cat.G (240 nmol/L) induced only a moderate platelet activation when added to a PMN-platelet mixture. However, when Cat.G (240 nmol/L) and HLE (380 nmol/L) were added together, the resulting platelet activation was strictly comparable to that corresponding to the addition of N-formyl-Met-Leu-Phe (P > .05) in terms of aggregation, dense and alpha granule secretion, and thromboxane B2 production. In fact, Elafin, a specific HLE inhibitor, when added to the PMN-platelet cooperation system triggered by N-formyl-Met-Leu-Phe, prevented platelet activation within the same range of concentrations as for inhibition of HLE activity. In conclusion, we now show that not only Cat.G, but also HLE is involved in the PMN-mediated platelet activation.
Renesto
P
P
Unité de Pharmacologie Cellulaire, Unité Associée Institut Pasteur/INSERM 285, Institut Pasteur, Paris, France.
Chignard
M
M
D000595:Amino Acid Sequence; D056649:Cathepsin G; D002403:Cathepsins / Q000008:administration & dosage*; D004357:Drug Synergism; D006801:Humans; D066298:In Vitro Techniques; D008969:Molecular Sequence Data; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology; D009504:Neutrophils / Q000201:enzymology*; D010196:Pancreatic Elastase / Q000008:administration & dosage* / Q000037:antagonists & inhibitors; D015539:Platelet Activation / Q000187:drug effects*; D053491:Proteinase Inhibitory Proteins, Secretory; D011506:Proteins; D012697:Serine Endopeptidases; D015842:Serine Proteinase Inhibitors / Q000494:pharmacology
D053491:Proteinase Inhibitory Proteins, Secretory; D011506:Proteins; D015842:Serine Proteinase Inhibitors; D009240:N-Formylmethionine Leucyl-Phenylalanine; D002403:Cathepsins; D012697:Serine Endopeptidases; C534094:CTSG protein, human; D056649:Cathepsin G; D010196:Pancreatic Elastase