VEGF-D deficiency causes hyperlipidemia and delayed clearance of chylomicron remnants

Objective: Dyslipidemia is one of the key factors behind coronary heart disease. Blood and lymphatic vessels play pivotal roles in both lipoprotein metabolism and development of atherosclerotic plaques. Recent studies have linked members of Vascular Endothelial Growth Factor (VEGF) family to lipid metabolism but the function of VEGF-D has remained unexplored. Here we investigated how the deletion of VEGF-D affects lipid and lipoprotein metabolism in atherogenic LDLR-/-ApoB100/100 mice. Approach and Results: Deletion of VEGF-D (Vegfd-/-LDLR-/-ApoB100/100) led to markedly elevated plasma cholesterol and triglyceride levels without an increase in atherogenesis. Size distribution and hepatic lipid uptake studies confirmed a delayed clearance of large chylomicron remnant particles that cannot easily penetrate through the vascular endothelium. Mechanistically, the inhibition of VEGF-D signaling significantly decreased the hepatic expression of syndecan 1 (SDC1), which is one of the main receptors for chylomicron remnant uptake when LDLR is absent. Immunohistochemical staining confirmed reduced expression of SDC1 in the sinusoidal surface of hepatocytes in VEGF-D deficient mice. Furthermore, hepatic RNA sequencing revealed that VEGF-D is also an important regulator of genes related to lipid metabolism and inflammation. The lack of VEGF-D signaling via VEGF receptor 3 led to lowered expression of genes regulating triglyceride and cholesterol production as well as downregulation of peroxisomal ß-oxidation pathway. Conclusions: These results demonstrate that VEGF-D, a powerful lymphangiogenic and angiogenic growth factor, is also a major regulator of chylomicron metabolism in mice. Overall design: Gene expression profiling of mouse liver tissue from control and VEGF-D knock-out mice. Control and VEGF-D KO mice were both in C57Bl/6 and atherosclerotic background, i.e., deficient of LDLR and expressing only apolipoprotein B100.

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Tirronen A, Vuorio T, Kettunen S, Hokkanen K, Ramms B, Niskanen H, Laakso H, Kaikkonen MU, Jauhiainen M, Gordts PLSM, Ylä-Herttuala S