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Widespread Coronary Dysfunction in the Absence of HDL Receptor SR-B1 in an Ischemic Cardiomyopathy Mouse Model.

ABSTRACT: Reduced clearance of lipoproteins by HDL scavenger receptor class B1 (SR-B1) plays an important role in occlusive coronary artery disease. However, it is not clear how much microvascular dysfunction contributes to ischemic cardiomyopathy. Our aim was to determine the distribution of vascular dysfunction in vivo in the coronary circulation of male mice after brief exposure to Paigen high fat diet, and whether this vasomotor dysfunction involved nitric oxide (NO) and or endothelium derived hyperpolarization factors (EDHF). We utilised mice with hypomorphic ApoE lipoprotein that lacked SR-B1 (SR-B1-/-/ApoER61h/h, n?=?8) or were heterozygous for SR-B1 (SR-B1+/-/ApoER61h/h, n?=?8) to investigate coronary dilator function with synchrotron microangiography. Partially occlusive stenoses were observed in vivo in SR-B1 deficient mice only. Increases in artery-arteriole calibre to acetylcholine and sodium nitroprusside stimulation were absent in SR-B1 deficient mice. Residual dilation to acetylcholine following L-NAME (50?mg/kg) and sodium meclofenamate (3?mg/kg) blockade was present in both mouse groups, except at occlusions, indicating that EDHF was not impaired. We show that SR-B1 deficiency caused impairment of NO-mediated dilation of conductance and microvessels. Our findings also suggest EDHF and prostanoids are important for global perfusion, but ultimately the loss of NO-mediated vasodilation contributes to atherothrombotic progression in ischemic cardiomyopathy.

SUBMITTER: Pearson JT

PROVIDER: S-EPMC5741771 | biostudies-literature | 2017 Dec

REPOSITORIES: biostudies-literature

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Widespread Coronary Dysfunction in the Absence of HDL Receptor SR-B1 in an Ischemic Cardiomyopathy Mouse Model.

Pearson James T JT Yoshimoto Misa M Chen Yi Ching YC Sultani Rohullah R Edgley Amanda J AJ Nakaoka Hajime H Nishida Makoto M Umetani Keiji K Waddingham Mark T MT Jin Hui-Ling HL Zhang Yuan Y Kelly Darren J DJ Schwenke Daryl O DO Inagaki Tadakatsu T Tsuchimochi Hirotsugu H Komuro Issei I Yamashita Shizuya S Shirai Mikiyasu M

Scientific reports 20171222 1

Reduced clearance of lipoproteins by HDL scavenger receptor class B1 (SR-B1) plays an important role in occlusive coronary artery disease. However, it is not clear how much microvascular dysfunction contributes to ischemic cardiomyopathy. Our aim was to determine the distribution of vascular dysfunction in vivo in the coronary circulation of male mice after brief exposure to Paigen high fat diet, and whether this vasomotor dysfunction involved nitric oxide (NO) and or endothelium derived hyperpo ...[more]

PMID: 29273789

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Project description:BackgroundThe survival benefit of a strategy of coronary-artery bypass grafting (CABG) added to guideline-directed medical therapy, as compared with medical therapy alone, in patients with coronary artery disease, heart failure, and severe left ventricular systolic dysfunction remains unclear.MethodsFrom July 2002 to May 2007, a total of 1212 patients with an ejection fraction of 35% or less and coronary artery disease amenable to CABG were randomly assigned to undergo CABG plus medical therapy (CABG group, 610 patients) or medical therapy alone (medical-therapy group, 602 patients). The primary outcome was death from any cause. Major secondary outcomes included death from cardiovascular causes and death from any cause or hospitalization for cardiovascular causes. The median duration of follow-up, including the current extended-follow-up study, was 9.8 years.ResultsA primary outcome event occurred in 359 patients (58.9%) in the CABG group and in 398 patients (66.1%) in the medical-therapy group (hazard ratio with CABG vs. medical therapy, 0.84; 95% confidence interval [CI], 0.73 to 0.97; P=0.02 by log-rank test). A total of 247 patients (40.5%) in the CABG group and 297 patients (49.3%) in the medical-therapy group died from cardiovascular causes (hazard ratio, 0.79; 95% CI, 0.66 to 0.93; P=0.006 by log-rank test). Death from any cause or hospitalization for cardiovascular causes occurred in 467 patients (76.6%) in the CABG group and in 524 patients (87.0%) in the medical-therapy group (hazard ratio, 0.72; 95% CI, 0.64 to 0.82; P<0.001 by log-rank test).ConclusionsIn a cohort of patients with ischemic cardiomyopathy, the rates of death from any cause, death from cardiovascular causes, and death from any cause or hospitalization for cardiovascular causes were significantly lower over 10 years among patients who underwent CABG in addition to receiving medical therapy than among those who received medical therapy alone. (Funded by the National Institutes of Health; STICH [and STICHES] ClinicalTrials.gov number, NCT00023595.).

Project description:BackgroundSR-B1 (scavenger receptor class B type 1)/LDLR (low-density lipoprotein receptor) double knockout mice fed a high-fat, high-cholesterol diet containing cholate exhibit coronary artery disease characterized by occlusive coronary artery atherosclerosis, platelet accumulation in coronary arteries, and myocardial fibrosis. Platelets are involved in atherosclerosis development, and PAR (protease-activated receptor) 4 has a prominent role in platelet function in mice. However, the role of PAR4 on coronary artery disease in mice has not been tested.MethodsWe tested the effects of a PAR4 inhibitory pepducin (RAG8) on diet-induced aortic sinus and coronary artery atherosclerosis, platelet accumulation in atherosclerotic coronary arteries, and myocardial fibrosis in SR-B1/LDLR double knockout mice. SR-B1/LDLR double knockout mice were fed a high-fat, high-cholesterol diet containing cholate and injected daily with 20 mg/kg of either the RAG8 pepducin or a control reverse-sequence pepducin (SRQ8) for 20 days.ResultsPlatelets from the RAG8-treated mice exhibited reduced thrombin and PAR4 agonist peptide-mediated activation compared with those from control SRQ8-treated mice when tested ex vivo. Although aortic sinus atherosclerosis levels did not differ, RAG8-treated mice exhibited reduced coronary artery atherosclerosis, reduced platelet accumulation in atherosclerotic coronary arteries, and reduced myocardial fibrosis. These protective effects were not accompanied by changes in circulating lipids, inflammatory cytokines, or immune cells. However, RAG8-treated mice exhibited reduced VCAM-1 (vascular cell adhesion molecule 1) protein levels in nonatherosclerotic coronary artery cross sections and reduced leukocyte accumulation in atherosclerotic coronary artery cross sections compared with those from SRQ8-treated mice.ConclusionsThe PAR4 inhibitory RAG8 pepducin reduced coronary artery atherosclerosis and myocardial fibrosis in SR-B1/LDLR double knockout mice fed a high-fat, high-cholesterol diet containing cholate. Furthermore, RAG8 reduced VCAM-1 in nonatherosclerotic coronary arteries and reduced leukocyte and platelet accumulation in atherosclerotic coronary arteries. These findings identify PAR4 as an attractive target in reducing coronary artery disease development, and the use of RAG8 may potentially be beneficial in cardiovascular disease.

Project description:Heart failure (HF) is a worldwide pandemic with an unacceptable high level of morbidity and mortality. Understanding the different pathophysiological mechanisms will contribute to prevention and individualized therapy of HF. We established mouse models for ischemic cardiomyopathy (ICM) and dilated cardiomyopathy (DCM) by inducing myocardial infarction (MI) and Coxsackievirus B3 infection, respectively. Isobaric tags for relative and absolute quantitation and liquid chromatography coupled with tandem mass spectrometry technology was used to identify the protein expression profiles in control and failing hearts. A total of 1,638 proteins were identified and compared in this proteomics analysis. Among them, 286 proteins were differently expressed. Gene ontology, KEGG pathway and ingenuity pathway analysis was performed to systematically assess the potential connections of the differentially expressed proteins to biological functions. Compared with control group, the differentially expressed proteins derived from the hearts of ICM and DCM mice were partially similar and mainly modulated in oxidative phosphorylation, metabolism and protein folding pathways. Moreover, difference still existed, the differentially expressed proteins between DCM and ICM hearts were significantly modulated in oxidative phosphorylation, metabolic and AMPK signaling pathways. Confirmatory western bolt analysis demonstrated that SDHB was down-regulated in both ICM and DCM hearts, while UQCRQ, GLUT4 and adiponectin were up-regulated in ICM hearts. Adenosine triphosphate (ATP) concentration significantly decreased in both DCM and ICM hearts. The protein expression of phospho-AMPK? decreased significantly in DCM hearts, but increased in ICM. In summary, oxidative phosphorylation, cardiac metabolism, and protein folding play critical roles in the pathogenesis of HF. The diverse changes in protein expression profiles between failing hearts induced by either MI or CVB3 infection demonstrated the heterogeneity of HF. Understanding the differences in proteome profiles could offer more precise therapeutic options for HF.

Project description:ObjectiveIn patients with ischemic cardiomyopathy, coronary artery bypass grafting ensures better survival than medical therapy. However, the long-term clinical impact of complete revascularization remains unclear. This observational study aimed to evaluate the effects of complete revascularization on long-term survival and left ventricular functional recovery in patients with ischemic cardiomyopathy undergoing coronary artery bypass grafting.MethodsWe retrospectively reviewed outcomes of 498 patients with ischemic cardiomyopathy who underwent complete (n = 386) or incomplete (n = 112) myocardial revascularization between 1993 and 2015. The baseline characteristics were adjusted using inverse probability of treatment weighting to reduce the impact of treatment bias and potential confounding. The mean follow-up duration was 77.2 ± 42.8 months in survivors.ResultsThe overall 5-year survival rate (complete revascularization, 72.5% vs incomplete revascularization, 57.9%, P = .03) and freedom from all-cause death and/or readmission due to heart failure (54.5% vs 40.1%, P = .007) were significantly greater in patients with complete revascularization than those with incomplete revascularization. After adjustments using inverse probability of treatment weighting, the complete revascularization group demonstrated a lower risk of all-cause death (hazard ratio, 0.61; 95% confidence interval, 0.43-0.86; P = .005) and composite adverse events (hazard ratio, 0.59; 95% confidence interval, 0.44-0.79; P < .001) and a greater improvement in the left ventricular ejection fraction 1-year postoperatively (absolute change: 11.0 ± 11.9% vs 8.3 ± 11.4%, interaction effect P = .05) than the incomplete revascularization group.ConclusionsIn patients with ischemic cardiomyopathy undergoing coronary artery bypass grafting, complete revascularization was associated with better long-term outcomes and greater left ventricular functional recovery and should be encouraged whenever possible.

Dataset Information

Widespread Coronary Dysfunction in the Absence of HDL Receptor SR-B1 in an Ischemic Cardiomyopathy Mouse Model.

Publications

Widespread Coronary Dysfunction in the Absence of HDL Receptor SR-B1 in an Ischemic Cardiomyopathy Mouse Model.

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