Dr. Martinod will discuss the contribution of neutrophil extracellular traps (NETs) to thromboinflammation in chronic settings. Citrullinated histones, generated during NET formation by peptidylarginine deiminase 4 (PAD4) serve as useful biomarkers of ongoing NET formation. Studies in animal models show a protective effect of PAD4-deficiency in conditions of cardiac fibrosis and deep vein thrombosis. Cancer and metabolic syndrome both provide environments amenable to excess NET release in circulation, promoting pathological consequences systemically including in thrombosis and in cardiac dysfunction. PAD4 contribution to extracellular trap formation in other cell types, including eosinophils, will be discussed.