A Murine Model of Hyperlipidemia&#45;Induced Heart Failure with Preserved Ejection Fraction

The pathophysiology of heart failure with preserved ejection fraction (HFpEF) driven by lipotoxicity is incompletely understood. Given the urgent need for ...

University of Miami Leonard M. Miller School of Medicine

Approximately 14% of the general population suffer from chronic kidney disease that can lead to acute kidney injury (AKI), a condition with up to 50% mortality for which there is no effective treatment. Hypertension, diabetes, and cardiovascular disease are the main comorbidities, and more than 660,000 Americans have kidney failure. β-Adrenergic receptors (βARs) have been extensively studied in association with lung and cardiovascular disease, but with limited scope in kidney and renal diseases. βARs are expressed in multiple parts of the kidney including proximal and distal convoluted tubules, glomeruli, and podocytes. Classical and noncanonical βAR signaling pathways interface with other intracellular mechanisms in the kidney to regulate important cellular functions including renal blood flow, electrolyte balance and salt handling, and tubular function that in turn exert control over critical physiology and pathology such as blood pressure and inflammatory responses. Nephroprotection through activation of βARs has surfaced as a promising field of investigation; however, there is limited data on the pharmacology and potential side effects of renal βAR modulation. Here, we provide updates on some of the major areas of preclinical kidney research involving βAR signaling that have advanced to describe molecular pathways and identify potential drug targets some of which are currently under clinical development for the treatment of kidney-related diseases.

β-Adrenergic receptor agonism as a therapeutic strategy for kidney disease.

Background The pathways of diastolic dysfunction and heart failure with preserved ejection fraction driven by lipotoxicity with metabolic syndrome are incompletely understood. Thus, there is an urgent need for animal models that accurately mimic the metabolic and cardiovascular phenotypes of this phenogroup for mechanistic studies. Methods and Results Hyperlipidemia was induced in WT-129 mice by 4 weeks of biweekly poloxamer-407 intraperitoneal injections with or without a single intravenous injection of adeno-associatedvirus 9-cardiac troponin T-low-density lipoprotein receptor (n=31), or single intravenous injection with adeno-associatedvirus 9-cardiac troponin T-low-density lipoprotein receptor alone (n=10). Treatment groups were compared with untreated or placebo controls (n=37). Echocardiography, blood pressure, whole-body plethysmography, ECG telemetry, activity wheel monitoring, and biochemical and histological changes were assessed at 4 to 8 weeks. At 4 weeks, double treatment conferred diastolic dysfunction, preserved ejection fraction, and increased left ventricular wall thickness. Blood pressure and whole-body plethysmography results were normal, but respiration decreased at 8 weeks (<0.01). ECG and activity wheel monitoring, respectively, indicated heart block and decreased exercise activity (<0.001). Double treatment promoted elevated myocardial lipids including total cholesterol, fibrosis, increased wet/dry lung (<0.001) and heart weight/body weight (<0.05). Xanthelasma, ascites, and cardiac ischemia were evident in double and single (p407) groups. Sudden death occurred between 6 and 12 weeks in double and single (p407) treatment groups. Conclusions We present a novel model of heart failure with preserved ejection fraction driven by dyslipidemia where mice acquire diastolic dysfunction, arrhythmia, cardiac hypertrophy, fibrosis, pulmonary congestion, exercise intolerance, and preserved ejection fraction in the absence of obesity, hypertension, kidney disease, or diabetes. The model can be applied to dissect pathways of metabolic syndrome that drive diastolic dysfunction in this lipotoxicity-mediated heart failure with preserved ejection fraction phenogroup mimic.

Mouse Model of Heart Failure With Preserved Ejection Fraction Driven by Hyperlipidemia and Enhanced Cardiac Low-Density Lipoprotein Receptor Expression.

Echocardiography is frequently used to evaluate cardiac function in rodent models of cardiovascular disease. Whereas methods to acquire the commonly used echocardiography parameters are well-described in published protocols or manuals, many important parameters are ill-defined and often open to subjective interpretation. Such lack of uniformity has engendered conflicting interpretations of the same parameters in published literature. In particular, parameters such as mitral regurgitation, mitral stenosis, pulmonary regurgitation, and aortic regurgitation that are required to define more esoteric etiologies in rarer mouse models often remain equivocal. The aim of this methods paper is to provide a practical guide to the acquisition and interpretation of infrequently used echocardiography parameters and set a framework for comprehensive analyses of right ventricle (RV), pulmonary artery (PA) pulmonary valve (PV), left atrium (LA), mitral valve (MV), and aortic valve (AoV) structure and function.

Echocardiography protocol: A tool for infrequently used parameters in mice.

Alport syndrome (AS) is caused by mutations in type IV collagen genes that typically target and compromise the integrity of basement membranes in kidney, ocular, and sensorineural cochlear tissues. Type IV and V collagens are also integral components of arterial walls, and whereas collagenopathies including AS are implicated in aortic disease, the incidence of aortic aneurysm in AS is unknown probably because of underreporting. Consequently, AS is not presently considered an independent risk factor for aortic aneurysm and more detailed case studies including histological evidence of basement membrane abnormalities are needed to determine such a possible linkage.

Ascending aortic aneurysm and histopathology in Alport syndrome: a case report.

COVID-19 pneumonia causes acute lung injury and acute respiratory distress syndrome (ALI/ARDS) characterized by early pulmonary endothelial and epithelial injuries with altered pulmonary diffusing capacity and obstructive or restrictive physiology. Growth hormone-releasing hormone receptor (GHRH-R) is expressed in the lung and heart. GHRH-R antagonist, MIA-602, has been reported to modulate immune responses to bleomycin lung injury and inflammation in granulomatous sarcoidosis. We hypothesized that MIA-602 would attenuate rVSV-SARS-CoV-2-induced pulmonary dysfunction and heart injury in a BSL-2 mouse model. Male and female K18-htg mice were inoculated with SARS-CoV-2/USA-WA1/2020, BSL-2-compliant recombinant VSV-eGFP-SARS-CoV-2-Spike (rVSV-SARS-CoV-2), or PBS, and lung viral load, weight loss, histopathology, and gene expression were compared. K18-htg mice infected with rVSV-SARS-CoV-2 were treated daily with subcutaneous MIA-602 or vehicle and conscious, unrestrained plethysmography performed on days 0, 3, and 5 (n = 7 to 8). Five days after infection mice were killed, and blood and tissues collected for histopathology and protein/gene expression. Both native SARS-CoV-2 and rVSV-SARS-CoV-2 presented similar patterns of weight loss, infectivity (~60%), and histopathologic changes. Daily treatment with MIA-602 conferred weight recovery, reduced lung perivascular inflammation/pneumonia, and decreased lung/heart ICAM-1 expression compared to vehicle. MIA-602 rescued altered respiratory rate, increased expiratory parameters (Te, PEF, EEP), and normalized airflow parameters (Penh and Rpef) compared to vehicle, consistent with decreased airway inflammation. RNASeq followed by protein analysis revealed heightened levels of inflammation and end-stage necroptosis markers, including ZBP1 and pMLKL induced by rVSV-SARS-CoV-2, that were normalized by MIA-602 treatment, consistent with an anti-inflammatory and pro-survival mechanism of action in this preclinical model of COVID-19 pneumonia.

Growth hormone-releasing hormone receptor antagonist MIA-602 attenuates cardiopulmonary injury induced by BSL-2 rVSV-SARS-CoV-2 in hACE2 mice.

Geleophysic dysplasia-1 (GD1) is an autosomal recessive disorder caused by ADAMTS-like 2 (ADAMTSL2) variants. It is characterized by distinctive facial features, limited joint mobility, short stature, brachydactyly, and life-threatening cardiorespiratory complications. The clinical spectrum spans from perinatal lethality to milder adult phenotypes. We developed and characterized cellular and mouse models, to replicate the genetic profile of a patient who is compound heterozygous for 2 ADAMTSL2 variants, namely p.R61H and p.A165T. The impairment of ADAMTSL2 secretion was observed in both variants, but p.A165T exhibited a more severe impact. Mice carrying different allelic combinations revealed a spectrum of phenotypic severity, from lethality in knockout homozygotes to mild growth impairment observed in adult p.R61H homozygotes. Homozygous and hemizygous p.A165T mice survived but displayed severe respiratory and cardiac dysfunction. The respiratory dysfunction mainly affected the expiration phase, and some of these animals had microscopic post-obstructive pneumonia. Echocardiograms and MRI studies revealed a significant systolic dysfunction, accompanied by a reduction of the aortic root size. Histology verified the presence of hypertrophic cardiomyopathy with myocyte hypertrophy, chondroid metaplasia, and mild interstitial fibrosis. This study revealed a substantial correlation between the degree of impaired ADAMTSL2 secretion and the severity of the observed phenotype in GD1.

Ali Kamiar

Interdisciplinary Stem Cell Institute,
Department of Molecular and Cellular Pharmacology

University of Miami Leonard M. Miller School of Medicine

A Murine Model of Hyperlipidemia-Induced Heart Failure with Preserved Ejection Fraction

Ali Kamiar

.css-o250i3{font-size:18px;font-family:Open Sans,sans-serif;line-height:21.6px;}Interdisciplinary Stem Cell Institute,Department of Molecular and Cellular Pharmacology

University of Miami Leonard M. Miller School of Medicine

A Murine Model of Hyperlipidemia-Induced Heart Failure with Preserved Ejection Fraction

Interdisciplinary Stem Cell Institute,
Department of Molecular and Cellular Pharmacology