Objective: Angiopoietin-like protein 3 (ANGPTL3) and 4 (ANGPTL4) are secreted proteins that inhibit lipoprotein lipase in vitro. Genetic variants at the ANGPTL3 and ANGPTL4 gene loci are significantly associated with plasma lipid traits. The aim of this study was to evaluate the association of plasma ANGPTL3 and ANGPTL4 concentrations with lipid and metabolic traits in a large community-based sample.
Approach and results: Plasma ANGPTL3 and ANGPTL4 levels were measured in 1770 subjects using a validated ELISA assay. A Pearson unadjusted correlation analysis and a linear regression analysis adjusting for age, sex, and race were performed. ANGPTL3 levels were significantly positively associated with low-density lipoprotein cholesterol and high-density lipoprotein cholesterol levels (both P<2×10(-5)) but not triglycerides. In contrast, ANGPTL4 levels were significantly negatively associated with low-density lipoprotein cholesterol and high-density lipoprotein cholesterol (both P<2×10(-5)) and positively associated with triglycerides (P=0.003). In addition, ANGPTL4, but not ANGPTL3, levels were significantly positively associated with fasting blood glucose and metabolic syndrome.
Conclusions: Despite having similar biochemical effects in vitro, plasma ANGPTL3 and ANGPTL4 concentrations have nearly opposite relationships with plasma lipids. ANGPTL4 is strongly negatively associated with low-density lipoprotein cholesterol and high-density lipoprotein cholesterol and positively with multiple features of the metabolic syndrome including triglycerides, whereas ANGPTL3 is positively associated with low-density lipoprotein cholesterol and high-density lipoprotein cholesterol and not with metabolic syndrome traits including triglycerides. Although ANGPTL3 and ANGPTL4 both inhibit lipoprotein lipase in vitro and influence lipoprotein metabolism in vivo, the physiology of these related proteins and their effects on lipoproteins is clearly divergent and complex.
Keywords: angiopoietins; cholesterol, HDL; cholesterol, LDL; diabetes mellitus; epidemiology; lipid metabolism; lipids; lipoproteins; triglycerides.