Definition of the metabolic pattern of ANGPTL3 deficient mice on a chow diet and under dysmetabolic conditions

Abstract

Aim: ANGPTL3 controls lipid and lipoprotein metabolism through lipoprotein lipase and endothelial lipase inhibition and the prevention of lipoprotein-derived triglycerides hydrolyzation. Here we present the metabolic profile of ANGPTL3 deficient mice in physiology and during the development of metabolic disorders. Methods: Angptl3 KO mice (C57BL6/J background) and their littermate controls (wild-type, WT) were fed a chow and a High Fat Diet (HFD, 60%kcal from lipids) for 16 weeks. During the diet protocol, changes in lipids and lipoprotein profile, under fast, fed, and fast-refeed setting were assessed. The metabolic phenotype was assessed, with a Glucose Tolerance Test (GTT) and an Insulin Tolerance Test (ITT); the lipids absorption profile was assessed with an Oral Lipid Tolerance Test (OLTT). Results: ANGPTL3 KO mice fed ad libitum a chow diet are hypolipidemic (plasma triglycerides levels: 42,42±8,80 mg/dL in ANGPTL3 KO mice compared to 122,02±55,09 mg/dL in WT mice; plasma cholesterol levels: 44,00±9,11 mg/dL in ANGPTL3 KO mice compared to 76,51±15,87 mg/dL in WT mice). After 16h fasting, ANGPTL3 KO mice on a chow diet are hypolipidemic and display small lipoproteins less rich in cholesterol and triglycerides, as established in humans, and the same holds true for mice fed a HFD diet. On HFD, ANGPTL3 KO mice gain less body weight, suggesting an improved metabolic profile compared to WT animals. The hypolipidemia is conserved during all the timepoints of OLTT, both in mice on chow or HFD, suggesting a different lipid management; in spite, no significant differences in the circulating glycaemia has been proved with a GTT after 16h of fasting; likewise, a similar sensitivity to insulin has been outlined with an ITT after 4h of fasting. Conclusions: This metabolic profiling of ANGPTL3 KO mice on chow diet or HFD highlights that these mice are hypolipidemic and may have beneficial metabolic features compared to controls.