ApoE determines the metabolic fate of apoC-III

Hypertriglyceridemia results from accumulation of triglyceride (TG)-rich lipoproteins (TRLs) in the circulation and is associated with increased cardiovascular disease risk. ApoC-III is an apolipoprotein on TRLs and a prominent negative regulator of TG catabolism. We recently established that in vivo apoC-III predominantly inhibits LDLR and LRP1 mediated hepatic TRL clearance and that apoC-III enriched TRLs are preferentially cleared by syndecan-1 (SDC1). In this study, we determined the impact of apoE, a common ligand for all three receptors, on apoC-III metabolism using apoC-III antisense oligonucleotide (ASO) treatment in mice lacking apoE and functional SDC1 (Apoe(-/-) Ndst1(f/f) Alb-Cre+). ApoC-III ASO treatment significantly reduced plasma TG levels in Apoe(-/-) Ndst1(f/f) Alb-Cre+ mice without reducing hepatic VLDL production or improving hepatic TRL clearance. Further analysis revealed that apoC-III ASO treatment lowered plasma TGs in Apoe(-/-) Ndst1(f/f) Alb-Cre+ mice, which was associated with increased LPL activity in white adipose tissue (WAT) in the fed state. Finally, clinical data confirm that ASO-mediated lowering of apoC-III via volanesorsen can reduce plasma TG levels independent of the apoE isoform genotype. Our data indicate that apoE determines the metabolic impact of apoC-III as we establish that apoE is essential to mediate inhibition of TRL clearance by apoC-III and that in the absence of functional apoE apoC-III inhibits tissue LPL activity. Comparison of five mice with apoC-III antisense oligonucleotide against four control mice