A single injection of gain-of-function mutant PCSK9 adeno-associated virus vector induces cardiovascular calcification in mice with no genetic modification

Atherosclerosis. 2016 Aug;251:109-118. doi: 10.1016/j.atherosclerosis.2016.06.011. Epub 2016 Jun 9.

Abstract

Background and aims: Studying atherosclerotic calcification in vivo requires mouse models with genetic modifications. Previous studies showed that injection of recombinant adeno-associated virus vector (AAV) encoding a gain-of-function mutant PCSK9 into mice promotes atherosclerosis. We aimed to study cardiovascular calcification induced by PCSK9 AAV in C57BL/6J mice.

Methods: 10 week-old C57BL/6J mice received a single injection of AAV encoding mutant mPCSK9 (rAAV8/D377Y-mPCSK9). Ldlr(-/-) mice served as positive controls. Mice consumed a high-fat, high-cholesterol diet for 15 or 20 weeks. Aortic calcification was assessed by fluorescence reflectance imaging (FRI) of a near-infrared calcium tracer.

Results: Serum levels of PCSK9 (0.14 μg/mL to 20 μg/mL, p < 0.01) and total cholesterol (82 mg/dL to 820 mg/dL, p < 0.01) increased within one week after injection and remained elevated for 20 weeks. Atherosclerotic lesion size was similar between PCSK9 AAV and Ldlr(-/-) mice. Aortic calcification was 0.01% ± 0.01 in PCSK9 AAV mice and 15.3% ± 6.1 in Ldlr(-/-) mice at 15 weeks (p < 0.01); by 20 weeks, the PCSK9 AAV mice aortic calcification grew to 12.4% ± 4.9. Tissue non-specific alkaline phosphatase activity was similar in PCSK9 AAV mice and Ldlr(-/-) mice at 15 and 20 weeks, respectively. As example of the utility of this model in testing modulators of calcification in vivo, PCSK9 AAV injection to sortilin-deficient mice demonstrated reduced aortic calcification by 46.3% (p < 0.05) compared to littermate controls.

Conclusions: A single injection of gain-of-function PCSK9 AAV into C57BL/6J mice is a useful tool to study cardiovascular calcification in mice with no genetic manipulation.

Keywords: AAV-PCSK9; Animal model; Cardiovascular calcification.

MeSH terms

  • Adaptor Proteins, Vesicular Transport / metabolism
  • Animals
  • Atherosclerosis / metabolism
  • Calcinosis / pathology*
  • Cholesterol / metabolism
  • Dependovirus
  • Disease Models, Animal
  • Female
  • Genetic Vectors
  • Liver / metabolism
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Mice, Transgenic
  • Microscopy, Fluorescence
  • Mutation*
  • Proprotein Convertase 9 / genetics*
  • Proprotein Convertases / genetics
  • Receptors, LDL / genetics

Substances

  • Adaptor Proteins, Vesicular Transport
  • Receptors, LDL
  • Cholesterol
  • Pcsk9 protein, mouse
  • Proprotein Convertase 9
  • Proprotein Convertases
  • sortilin