Cathepsin G-dependent modulation of platelet thrombus formation in vivo by blood neutrophils.
Neutrophils are consistently associated with arterial thrombotic morbidity in human clinical studies but the causal basis for this association is unclear. We tested the hypothesis that neutrophils modulate platelet activation and thrombus formation in vivo in a cathepsin G-dependent manner. Neutrophils enhanced aggregation of human platelets in vitro in dose-dependent fashion and this effect was diminished by pharmacologic inhibition of cathepsin G activity and knockdown of cathepsin G expression. Tail bleeding time in the mouse was prolonged by a cathepsin G inhibitor and in cathepsin G knockout mice, and formation of neutrophil-platelet conjugates in blood that was shed from transected tails was reduced in the absence of cathepsin G. Bleeding time was highly correlated with blood neutrophil count in wildtype but not cathepsin G deficient mice. In the presence of elevated blood neutrophil counts, the anti-thrombotic effect of cathepsin G inhibition was greater than that of aspirin and additive to it when administered in combination. Both pharmacologic inhibition of cathepsin G and its congenital absence prolonged the time for platelet thrombus to form in ferric chloride-injured mouse mesenteric arterioles. In a vaso-occlusive model of ischemic stroke, inhibition of cathepsin G and its congenital absence improved cerebral blood flow, reduced histologic brain injury, and improved neurobehavioral outcome. These experiments demonstrate that neutrophil cathepsin G is a physiologic modulator of platelet thrombus formation in vivo and has potential as a target for novel anti-thrombotic therapies.
Department of Anesthesiology/Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America. nfaraday@jhmi.edu
Nauder
N
Faraday
Kathryn
K
Schunke
Sofiyan
S
Saleem
Juan
J
Fu
Bing
B
Wang
Jian
J
Zhang
Craig
C
Morrell
Sylvain
S
Dore
D000328:Adult; D000818:Animals; D001792:Blood Platelets / Q000473:pathology / Q000502:physiology; D056649:Cathepsin G / Q000502:physiology*; D005260:Female; D006487:Hemostasis / Q000235:genetics; D006801:Humans; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009504:Neutrophils / Q000201:enzymology / Q000502:physiology*; D010974:Platelet Aggregation / Q000235:genetics*; D013927:Thrombosis / Q000235:genetics* / Q000378:metabolism
D056649:Cathepsin G