Angptl4 Protects against Severe Proinflammatory Effects of Saturated Fat by Inhibiting Fatty Acid Uptake into Mesenteric Lymph Node Macrophages

Dietary saturated fat is linked to numerous chronic diseases, including cardiovascular disease. Here we show that the lipoprotein lipase inhibitor Angptl4 protects against the pronounced pro-inflammatory effects of dietary saturated fat. Strikingly, in mice lacking Angptl4, dietary saturated fat induces a severe and ultimately lethal phenotype characterized by fibrinopurulent peritonitis, ascites, intestinal fibrosis, and cachexia. These abnormalities are preceded by a massive acute phase response induced by saturated but not unsaturated fat or medium-chain fat, originating in the mesenteric lymph nodes (MLNs). MLNs undergo dramatic expansion and contain numerous lipid laden macrophages. In peritoneal macrophages incubated with chyle, Angptl4 dramatically reduced macrophage foam cell formation, inflammatory gene expression, and chyle-induced activation of the ER stress pathway. The data reveal a novel mechanism in which induction of macrophage Angptl4 by fatty acids serves to reduce postprandial lipid uptake from fatty chyle into MLN-resident macrophages by inhibiting triglyceride hydrolysis, thereby preventing macrophage activation and foam cell formation and protecting against progressive, uncontrolled dietary saturated fat-induced inflammation.