Loss of angiopoietin-like 4 (ANGPTL4) in mice with diet-induced obesity uncouples visceral obesity from glucose intolerance partly via the gut microbiota.

AIMS/HYPOTHESIS: Angiopoietin-like 4 (ANGPTL4) is an important regulator of triacylglycerol metabolism, carrying out this role by inhibiting the enzymes lipoprotein lipase and pancreatic lipase. ANGPTL4 is a potential target for ameliorating cardiometabolic diseases. Although ANGPTL4 has been implicated in obesity, the study of the direct role of ANGPTL4 in diet-induced obesity and related metabolic dysfunction is hampered by the massive acute-phase response and development of lethal chylous ascites and peritonitis in Angptl4-/- mice fed a standard high-fat diet. The aim of this study was to better characterise the role of ANGPTL4 in glucose homeostasis and metabolic dysfunction during obesity.

METHODS: We chronically fed wild-type (WT) and Angptl4-/- mice a diet rich in unsaturated fatty acids and cholesterol, combined with fructose in drinking water, and studied metabolic function. The role of the gut microbiota was investigated by orally administering a mixture of antibiotics (ampicillin, neomycin, metronidazole). Glucose homeostasis was assessed via i.p. glucose and insulin tolerance tests.

RESULTS: Mice lacking ANGPTL4 displayed an increase in body weight gain, visceral adipose tissue mass, visceral adipose tissue lipoprotein lipase activity and visceral adipose tissue inflammation compared with WT mice. However, they also unexpectedly had markedly improved glucose tolerance, which was accompanied by elevated insulin levels. Loss of ANGPTL4 did not affect glucose-stimulated insulin secretion in isolated pancreatic islets. Since the gut microbiota have been suggested to influence insulin secretion, and because ANGPTL4 has been proposed to link the gut microbiota to host metabolism, we hypothesised a potential role of the gut microbiota. Gut microbiota composition was significantly different between Angptl4-/- mice and WT mice. Interestingly, suppression of the gut microbiota using antibiotics largely abolished the differences in glucose tolerance and insulin levels between WT and Angptl4-/- mice.

CONCLUSIONS/INTERPRETATION: Despite increasing visceral fat mass, inactivation of ANGPTL4 improves glucose tolerance, at least partly via a gut microbiota-dependent mechanism.