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Nat Med. 2017 Sep;23(9):1086-1094. doi: 10.1038/nm.4390. Epub 2017 Aug 21.

A human APOC3 missense variant and monoclonal antibody accelerate apoC-III clearance and lower triglyceride-rich lipoprotein levels.

Author information

1
Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
2
Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
3
Biomedical Mass Spectrometry Center, Schools of the Health Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania, USA.
4
Staten Biotechnology BV, Nijmegen, the Netherlands.
5
argenx BVBA, Zwjnaarde, Belgium.
6
FairJourney Biologics, Porto, Portugal.
7
Department of Biostatistics, Boston University School of Public Health, Boston, Massachusetts, USA.
8
Center for Genomic Medicine, Massachusetts General Hospital, Boston, Massachusetts, USA.
9
Department of Medicine, Harvard Medical School, Boston, Massachusetts, USA.
10
Program in Medical and Population Genetics, Broad Institute, Cambridge, Massachusetts, USA.
11
Division of Molecular Medicine, Department of Medicine, Columbia University, New York, New York, USA.
12
Department of Cell Biology, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, USA.

Abstract

Recent large-scale genetic sequencing efforts have identified rare coding variants in genes in the triglyceride-rich lipoprotein (TRL) clearance pathway that are protective against coronary heart disease (CHD), independently of LDL cholesterol (LDL-C) levels. Insight into the mechanisms of protection of these variants may facilitate the development of new therapies for lowering TRL levels. The gene APOC3 encodes apoC-III, a critical inhibitor of triglyceride (TG) lipolysis and remnant TRL clearance. Here we report a detailed interrogation of the mechanism of TRL lowering by the APOC3 Ala43Thr (A43T) variant, the only missense (rather than protein-truncating) variant in APOC3 reported to be TG lowering and protective against CHD. We found that both human APOC3 A43T heterozygotes and mice expressing human APOC3 A43T display markedly reduced circulating apoC-III levels. In mice, this reduction is due to impaired binding of A43T apoC-III to lipoproteins and accelerated renal catabolism of free apoC-III. Moreover, the reduced content of apoC-III in TRLs resulted in accelerated clearance of circulating TRLs. On the basis of this protective mechanism, we developed a monoclonal antibody targeting lipoprotein-bound human apoC-III that promotes circulating apoC-III clearance in mice expressing human APOC3 and enhances TRL catabolism in vivo. These data reveal the molecular mechanism by which a missense variant in APOC3 causes reduced circulating TG levels and, hence, protects from CHD. This protective mechanism has the potential to be exploited as a new therapeutic approach to reduce apoC-III levels and circulating TRL burden.

PMID:
28825717
PMCID:
PMC5669375
DOI:
10.1038/nm.4390
[Indexed for MEDLINE]
Free PMC Article

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