Neutrophil activation and NETosis are the major drivers of thrombosis in heparin-induced thrombocytopenia

José Perdomo; Halina H L Leung; Zohra Ahmadi; Feng Yan; James J H Chong; Freda H Passam; Beng H Chong

doi:10.1038/s41467-019-09160-7

Neutrophil activation and NETosis are the major drivers of thrombosis in heparin-induced thrombocytopenia

Nat Commun. 2019 Mar 21;10(1):1322. doi: 10.1038/s41467-019-09160-7.

Authors

José Perdomo¹, Halina H L Leung¹, Zohra Ahmadi¹, Feng Yan¹, James J H Chong^{2

3

4

5}, Freda H Passam¹, Beng H Chong^{6

7}

Affiliations

¹ Haematology Research Unit, St George and Sutherland Clinical School, Faculty of Medicine, University of New South Wales, Sydney, NSW, Australia.
² Sydney Medical School, The University of Sydney, Sydney, NSW, Australia.
³ Centre for Heart Research, Westmead Institute for Medical Research, The University of Sydney, Sydney, NSW, Australia.
⁴ Department of Cardiology, Westmead Hospital, Sydney, NSW, Australia.
⁵ Victor Chang Cardiac Research Institute, Darlinghurst, NSW, Australia.
⁶ Haematology Research Unit, St George and Sutherland Clinical School, Faculty of Medicine, University of New South Wales, Sydney, NSW, Australia. beng.chong@unsw.edu.au.
⁷ New South Wales Health Pathology, St George and Sutherland Hospitals, Sydney, NSW, Australia. beng.chong@unsw.edu.au.

Abstract

Heparin-induced thrombocytopenia/thrombosis (HIT) is a serious immune reaction to heparins, characterized by thrombocytopenia and often severe thrombosis with high morbidity and mortality. HIT is mediated by IgG antibodies against heparin/platelet factor 4 antigenic complexes. These complexes are thought to activate platelets leading to thrombocytopenia and thrombosis. Here we show that HIT immune complexes induce NETosis via interaction with FcγRIIa on neutrophils and through neutrophil-platelet association. HIT immune complexes induce formation of thrombi containing neutrophils, extracellular DNA, citrullinated histone H3 and platelets in a microfluidics system and in vivo, while neutrophil depletion abolishes thrombus formation. Absence of PAD4 or PAD4 inhibition with GSK484 abrogates thrombus formation but not thrombocytopenia, suggesting they are induced by separate mechanisms. NETs markers and neutrophils undergoing NETosis are present in HIT patients. Our findings demonstrating the involvement of NETosis in thrombosis will modify the current concept of HIT pathogenesis and may lead to new therapeutic strategies.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Animals
Antigen-Antibody Complex / biosynthesis
Blood Platelets / drug effects
Blood Platelets / immunology*
Citrullination
Enzyme Inhibitors / pharmacology
Extracellular Traps / chemistry
Extracellular Traps / drug effects
Extracellular Traps / immunology*
Gene Expression Regulation
Heparin / adverse effects*
Histones / genetics
Histones / immunology
Humans
Immunoglobulin G / biosynthesis
Mice
Mice, Transgenic
Microfluidic Analytical Techniques
Neutrophil Activation / drug effects
Neutrophil Activation / immunology
Neutrophils / drug effects
Neutrophils / immunology*
Platelet Activation / drug effects
Platelet Activation / immunology
Platelet Factor 4 / genetics
Platelet Factor 4 / immunology
Protein-Arginine Deiminase Type 4
Protein-Arginine Deiminases / antagonists & inhibitors
Protein-Arginine Deiminases / genetics
Protein-Arginine Deiminases / immunology
Receptors, IgG / genetics*
Receptors, IgG / immunology
Signal Transduction
Thrombocytopenia / chemically induced
Thrombocytopenia / immunology*
Thrombocytopenia / pathology
Thrombosis / chemically induced
Thrombosis / immunology*
Thrombosis / pathology
Thrombosis / prevention & control

Substances

Antigen-Antibody Complex
Enzyme Inhibitors
Fc gamma receptor IIA
Histones
Immunoglobulin G
PF4 protein, human
Receptors, IgG
Platelet Factor 4
Heparin
PADI4 protein, human
Protein-Arginine Deiminase Type 4
Protein-Arginine Deiminases
peptidylarginine deiminase 4, mouse