Inactivation of Apoc3 by CRISPR/Cas9 Protects Against Atherosclerosis in Hamsters.

ApoC3 is a secretory glycoprotein primarily synthesized by liver, which plays a crucial role in LPL (lipoprotein lipase)-mediated hydrolysis process of triglycerides in circulation. Over the past decades, growing lines of evidence from functional studies demonstrate that ApoC3 is positively correlated with the incidence of cardiovascular disease,1 leading to the clinical trials of ApoC3 antisense or monoclonal antibody.2 Surprisingly, although overexpression of human ApoC3 significantly accelerated atherosclerotic development in mice, the protective effect of ApoC3 deficiency on atherogenesis was not observed in knockout mice,3 thus implying that other genetically modified species need to be developed for the study of ApoC3-related dyslipidemia. Since Syrian golden hamsters resemble humans in respect with the metabolic profiling, we deleted Apoc3 gene in hamsters using CRISPR/Cas9 (clustered regularly interspaced short palindromic repeats/CRISPR associated protein 9) to investigate the relationship between ApoC3 and atherosclerosis (Figure [A]). Compared with wild-type group, triglyceride level was significantly reduced in ApoC3 KO (ApoC3−/−) hamsters on chow diet with no statistical differences in the levels of total cholesterol and HDL-C (high-density lipoprotein cholesterol) attributed to an inhibition of triglyceride accumulation in chow diet–fed hamsters after oral fat load without affecting hepatic VLDL (very low-density lipoprotein) secretion (Figure [B]), which was consistent with the phenotypes observed in ApoC3-deficient humans4; however, lipoprotein disc electrophoresis showed a reduction in VLDL fractions and an increase in LDL (low density lipoprotein) fractions in ApoC3−/− hamsters, indicating that ApoC3 deficiency enhanced the conversion of VLDL to LDL (Figure [B]). To better study the relationship between ApoC3 and atherosclerosis, we put wild-type and ApoC3−/− hamsters on high-cholesterol/high-fat diet. Our results showed that circulating triglyceride and total cholesterol levels were significantly reduced, but HDL-C levels were markedly increased in ApoC3−/− hamsters (Figure [C]). Furthermore, lipoprotein disc electrophoresis revealed a substantial reduction in the fractions of VLDL and LDL in high-cholesterol/high-fat-fed ApoC3−/− hamsters accompanied by an increase in HDL (Figure [C]). In line with the results of plasma lipids and lipoprotein distribution, ApoC3−/− hamsters showed reduced concentrations of ApoB (Apolipoprotein B) and ApoE (Apolipoprotein E), but elevated ApoA1 (Apolipoprotein A1) levels (Figure [C]), suggesting that ApoC3 deficiency clearly led to an antiatherogenic lipid profile. As expected, ApoC3−/− hamsters upon high-cholesterol/ high-fat diet exhibited less atherosclerotic lesions in both thoracic and abdominal arteries, which were the major parts with atherosclerotic development observed in humans; however, there was no statistical difference in the lesions in aortic arch and sinus between the 2 genotypes (Figure [D]). In conclusion, the present study reports a direct relationship between ApoC3 and atherogenesis in a humanlike animal model with ApoC3 deficiency: inactivation of