SiRNA-based inactivation of Angptl3 alleviates high-fat diet-induced MAFLD and atherosclerosis in LDLR-deficient hamsters

Angiopoietin-like protein 3 (Angptl3), a factor secreted by the liver, inhibits lipoprotein lipase and other lipases by forming a complex with Angptl4 and 8. However, whether inhibition of Angptl3 can alleviate hepatic lipid accumulation and atherosclerosis remains unclear. Therefore, this study explored the effect of small interfering RNA (siRNA)-based inactivation of Angptl3 on metabolic dysfunction-associated fatty liver disease (MAFLD) and atherosclerosis in male LDLR-deficient hamsters. Recombinant adeno-associated virus serotype 9 (AAV9) encoding Angptl3-siRNA or empty AAV (AAV9-null) were injected into male 4-month-old LDLR−/− hamsters via the jugular vein. Subsequently, all hamsters were administered with a 16-week high-fat diet (HFD) feeding to induce atherosclerosis. RT-PCR and pathological analysis were used to investigate the mechanism of hepatic lipid accumulation and detect atherosclerotic plaque formation in the heart and aorta. On HFD, Angptl3-siRNA-treated hamsters displayed significantly decreased plasma triglyceride (TG), total cholesterol, high-density lipoprotein-cholesterol, and glucose levels, compared with the AAV9-null hamsters. FPLC analysis further revealed a marked reduction of TG and cholesterol contents in VLDL/LDL fractions. Plasma apolipoprotein analysis showed relatively lower ApoB/ApoE levels and higher ApoA1 levels. Moreover, Angptl3-siRNA markedly accelerated the clearance of triglyceride-rich lipoproteins in LDLR−/− hamsters. Consistently, results from hepatic lipid extraction, Oil Red O and Sirius Red staining demonstrated that Angptl3-siRNA reduced hepatic lipid accumulation and ameliorated HFD-induced MAFLD. RT-PCR revealed a dramatic decrease in the expression of Acc1, Fasn, Srebp1c, Cd36, Fatp1, Tgfβ, Cd68, Tnfa, and Col1a1 as well as a marked increase in Abcg5, Abcg8, Ppara, and Cpt1 expression, which participated in fatty acid synthesis and oxidation, cholesterol synthesis and efflux, inflammation and fibrosis. Pathological analysis indicated that Angptl3-siRNA attenuated the formation of atherosclerotic plaques in the aortic root and aorta when compared with the control group. These findings demonstrated that siRNA-based inactivation of Angptl3 alleviated MAFLD and atherosclerosis induced by HFD in LDLR−/− hamsters, which further confirmed that inhibition of Angptl3 may provide a novel therapeutic approach for atherosclerosis by reducing hyperlipidemia and hepatic lipid accumulation.