Development of Human‐Like Advanced Coronary Plaques in Low‐Density Lipoprotein Receptor Knockout Pigs and Justification for Statin Treatment Before Formation of Atherosclerotic Plaques

Abstract

BackgroundAlthough clinical trials have proved that statin can be used prophylactically against cardiovascular events, the direct effects of statin on plaque development are not well understood. We generated low‐density lipoprotein receptor knockout (LDLR −/−) pigs to study the effects of early statin administration on development of atherosclerotic plaques, especially advanced plaques.Methods and Results LDLR −/− pigs were generated by targeted deletion of exon 4 of the LDLR gene. Given a standard chow diet, LDLR −/− pigs showed atherosclerotic lesions starting at 6 months of age. When 3‐month‐old LDLR −/− pigs were fed a high‐cholesterol, high‐fat (HCHF) diet for 4 months (HCHF group), human‐like advanced coronary plaques developed. We also fed 3‐month‐old LDLR −/− pigs an HCHF diet with pitavastatin for 4 months (Statin Prophylaxis Group). Although serum cholesterol concentrations did not differ significantly between the 2 groups, intravascular ultrasound revealed 52% reduced plaque volume in statin‐treated pigs. Pathological examination revealed most lesions (87%) in the statin prophylaxis group were early‐stage lesions, versus 45% in the HCHF diet group (P<0.01). Thin‐cap fibroatheroma characterized 40% of the plaques in the HCHF diet group versus 8% in the statin prophylaxis group (P<0.01), intraplaque hemorrhage characterized 11% versus 1% (P<0.01), and calcification characterized 22% versus 1% (P<0.01).ConclusionsResults of our large animal experiment support statin prophylaxis before the occurrence of atherosclerosis. Early statin treatment appears to retard development of coronary artery atherosclerosis and ensure lesion stability. In addition, the LDLR −/− pigs we developed represent a large animal model of human‐like advanced coronary plaque suitable for translational research.

Animal models of obesity and diabetes mellitus

“…On the basis of their anatomical and physiological similarities to humans, their high fertility and easy maintenance, the possibility of dietary and surgical interventions and the efficient and specific genetic modifications, pigs are promising models to overcome gaps between proof-of-concept models and clinical studies in obesity and diabetes mellitus research. In addition, pigs might serve as tissue donors for β-cell replacement therapies of Understanding the roles of ApoC-III in lipid metabolism and of triglycerides in atherosclerosis; evaluating drugs for hypertriglyceridemia 391 Expression of human ApoA 392,393 High plasma levels of human ApoA 393 Evaluating the pharmacology and efficacy of new drugs for atherosclerosis 393 Knockout of the gene encoding LDL receptor 394,395 Moderate (LDLR +/-) or severe (LDLR -/-) increase in total and LDL cholesterol on a standard diet; more severe on a high-fat, high-cholesterol diet 21 ; atherosclerotic lesions in the coronary arteries and abdominal aorta (LDLR -/-) 394,395 Developing and testing novel detection and treatment strategies for coronary and aortic atherosclerosis and its complications [394][395][396] Overexpression of LDL-PLA(2) 397 Increased postprandial plasma triglyceride levels; increased expression of pro-inflammatory genes in peripheral blood mononuclear cells 397 Studying the consequences of elevated circulating LDL-PLA(2) levels; testing LDL-PLA(2) inhibitors 397 ApoA, apolipoprotein(a); ApoC-III, apolipoprotein C-III; GIPR, glucose-dependent insulinotropic polypeptide receptor; HNF1A, hepatocyte nuclear factor 1α; LDL-PLA(2), LDL-associated phospholipase A2; PCSK9, proprotein convertase subtilisin/kexin type 9. *The pathological changes in this model may be caused by expression of mutant HNF1A and not be a consequence of diabetes mellitus.…”

Arterial Calcification in Diabetes Mellitus

“…Statins – like bisphosphonates – inhibit bone resorbing osteoclast-like cell function 149 while additionally limiting inflammatory osteogenic programs in VSM 150 . The former may explain why longer-term statin use (healthy survivors) may accrue increased coronary calcification with time 146 , while the latter has been used to argue for early intervention in preclinical porcine disease models 151 . Thus, physiological context and metabolic milieu significantly impacts the net impact of any intervention that directly or indirectly targets vascular mineralization.…”

Ossabaw Pigs With a PCSK9 Gain‐of‐Function Mutation Develop Accelerated Coronary Atherosclerotic Lesions: A Novel Model for Preclinical Studies

“…Indeed, others have realized the value of modeling atherosclerosis with naturally occurring mutations, knockout of LDLR or transgenic expression of PCSK9‐D374Y , and have showed significant elevations in total and LDLc . Unlike Ossabaw, the Yucatan and conventional pigs do not develop MetS when challenged with HFHC diet, and lesion formation in the Yucatan PCSK9 GOF pigs is not increased by chemically induced diabetes mellitus type 1 .…”

“…Experience with this model has shown that attaining a consistent effect on lesion development with a traditional breeding and selection approach is challenging . More recently, an LDLR gene knockout model has been reported in Yucatan and conventional swine . Homozygous animals had pronounced dyslipidemia, and after 4 to 6 months consuming a modified diet, some advanced lesion development was observed in the abdominal aorta and coronary arteries of Yucatan and conventional swine, respectively.…”