Cardiac Interstitial Fibrosis Research Articles

The interaction of choline and one-carbon / folate metabolism derangements on the cardiac remodeling process with or without diabetes

Proper nutrition helps protect from illness and disease. Choline (Ch), an essential molecule of substantial importance for the optimal development and function of several biological systems, plays a crucial role in the pathway of one-carbon metabolism. On the other hand, Ch-deprivation (CD) has been linked with abnormal fat metabolism, insulin resistance, and myocardial dysfunction. The Ch-deficiency setting is an established experimental model of non-alco¬holic steatohepatitis that resembles the human non-alcoholic fatty liver disease (NAFLD); a disease with constantly increasing incidence and prevalence. NAFLD, commonly associated with metabolic comorbidities such as obesity and type 2 diabetes mellitus, consists a high risk for cardiovascular disease. Experimental data of dietary CD through the administration of a Ch-deficient diet to rodents have revealed myocardial monocyte infiltration along with cardiac interstitial oedema and fibrosis, as well as a deleterious effect on cardiac valves that could lead to impaired heart mechanical properties which resemble to a restrictive pattern of cardiomyopathy characterised mainly by diastolic dysfunction. In a Ch-deprived diabetic experimental model, the diastolic heart failure has been characterized by a concentric hypertrophied myocardium, a left ventricular cavity with a thinner wall, and an increased left ventricular diastolic diameter, in addition to a left atrial dilatation that could also exert functional derangement and provoke arrhythmogenesis, thereby jeopardising cardiac output.

Molecular Imaging of Diffuse Cardiac Fibrosis with a Radiotracer That Targets Proteolyzed Collagen IV.

Purpose To develop an approach for in vivo detection of interstitial cardiac fibrosis using PET with a peptide tracer targeting proteolyzed collagen IV (T-peptide). Materials and Methods T-peptide was conjugated to the copper chelator MeCOSar (chemical name, 5-(8-methyl-3,6,10,13,16,19-hexaaza-bicyclo[6.6.6]icosan-1-ylamino)-5-oxopentanoic acid) and radiolabeled with copper 64 (64Cu). PET/CT scans were acquired following intravenous delivery of 64Cu-T-peptide-MeCOSar (0.25 mg/kg; 18 MBq ± 2.7 [SD]) to male transgenic mice overexpressing β2-adrenergic receptors with intermediate (7 months of age; n = 4 per group) to severe (10 months of age; n = 11 per group) cardiac fibrosis and their wild-type controls. PET scans were also performed following coadministration of the radiolabeled probe with nonlabeled T-peptide in excess to confirm binding specificity. PET data were analyzed by t tests for static scans and analysis of variance tests (one- or two-way) for dynamic scans. Results PET/CT scans revealed significantly elevated (2.24-4.26-fold; P < .05) 64Cu-T-peptide-MeCOSar binding in the fibrotic hearts of aged transgenic β2-adrenergic receptor mice across the entire 45-minute acquisition period compared with healthy controls. The cardiac tracer accumulation and presence of diffuse cardiac fibrosis in older animals were confirmed by gamma counting (P < .05) and histologic evaluation, respectively. Coadministration of a nonradiolabeled probe in excess abolished the elevated radiotracer binding in the aged transgenic hearts. Importantly, PET tracer accumulation was also detected in younger (7 months of age) transgenic mice with intermediate cardiac fibrosis, although this was only apparent from 20 minutes following injection (1.6-2.2-fold binding increase; P < .05). Conclusion The T-peptide PET tracer targeting proteolyzed collagen IV provided a sensitive and specific approach of detecting diffuse cardiac fibrosis at varying degrees of severity in a transgenic mouse model. Keywords: Diffuse Cardiac Fibrosis, Molecular Peptide Probe, Molecular Imaging, PET/CT © RSNA, 2024.

Prmt7 regulates the JAK/STAT/Socs3 signaling pathway in postmenopausal cardiomyopathy

Protein arginine methyltransferases (PRMTs) modulate diverse cellular processes, including stress responses. The present study explored the role of Prmt7 in protecting against menopause-associated cardiomyopathy. Mice with cardiac-specific Prmt7 ablation (cKO) exhibited sex-specific cardiomyopathy. Male cKO mice exhibited impaired cardiac function, myocardial hypertrophy, and interstitial fibrosis associated with increased oxidative stress. Interestingly, female cKO mice predominantly exhibited comparable phenotypes only after menopause or ovariectomy (OVX). Prmt7 inhibition in cardiomyocytes exacerbated doxorubicin (DOX)-induced oxidative stress and DNA double-strand breaks, along with apoptosis-related protein expression. Treatment with 17β-estradiol (E2) attenuated the DOX-induced decrease in Prmt7 expression in cardiomyocytes, and Prmt7 depletion abrogated the protective effect of E2 against DOX-induced cardiotoxicity. Transcriptome analysis of ovariectomized wild-type (WT) or cKO hearts and mechanical analysis of Prmt7-deficient cardiomyocytes demonstrated that Prmt7 is required for the control of the JAK/STAT signaling pathway by regulating the expression of suppressor of cytokine signaling 3 (Socs3), which is a negative feedback inhibitor of the JAK/STAT signaling pathway. These data indicate that Prmt7 has a sex-specific cardioprotective effect by regulating the JAK/STAT signaling pathway and, ultimately, may be a potential therapeutic tool for heart failure treatment depending on sex.

Cardiac recovery from pressure overload is not altered by thyroid hormone status in old mice.

Thyroid hormones (THs) are known to have various effects on the cardiovascular system. However, the impact of TH levels on preexisting cardiac diseases is still unclear. Pressure overload due to arterial hypertension or aortic stenosis and aging are major risk factors for the development of structural and functional abnormalities and subsequent heart failure. Here, we assessed the sensitivity to altered TH levels in aged mice with maladaptive cardiac hypertrophy and cardiac dysfunction induced by transverse aortic constriction (TAC). Mice at the age of 12 months underwent TAC and received T4 or anti-thyroid medication in drinking water over the course of 4 weeks after induction of left ventricular pressure overload. T4 excess or deprivation in older mice had no or only very little impact on cardiac function (fractional shortening), cardiac remodeling (cardiac wall thickness, heart weight, cardiomyocyte size, apoptosis, and interstitial fibrosis), and mortality. This is surprising because T4 excess or deprivation had significantly changed the outcome after TAC in young 8-week-old mice. Comparing the gene expression of deiodinases (Dio) 2 and 3 and TH receptor alpha (TRα) 1 and the dominant-negative acting isoform TRα2 between young and aged mice revealed that aged mice exhibited a higher expression of TRα2 and Dio3, while expression of Dio2 was reduced compared with young mice. These changes in Dio2 and 3 expressions might lead to reduced TH availability in the hearts of 12-month-old mice accompanied by reduced TRα action due to higher TRα2. In summary, our study shows that low and high TH availability have little impact on cardiac function and remodeling in older mice with preexisting pressure-induced cardiac damage. This observation seems to be the result of an altered expression of deiodinases and TRα isoforms, thus suggesting that even though cardiovascular risk is increasing with age, the response to TH stress may be dampened in certain conditions.

Overexpressing Mitogen-activated Protein Kinase Kinase 7 (MKK7) Alleviates Endoplasmic Reticulum Stress-induced Cardiac Dysfunction during Pressure Overload induced Heart Failure

Article Overexpressing Mitogen-activated Protein Kinase Kinase 7 (MKK7) Alleviates Endoplasmic Reticulum Stress-induced Cardiac Dysfunction during Pressure Overload induced Heart Failure Tayyiba Azam 1, * , Min Zi 1, Susanne S. Hille 2,3, Hongyuan Zhang 1, Elizabeth J. Cartwright 1, Oliver J. Müller 2,3, and Xin Wang 1 1 Faculty of Biology, Medicine, and Health, University of Manchester, Oxford RoadM13 9PTManchesterUK 2 Department of Internal Medicine III, University of Kiel24105KielGermany 3 DZHK, German Centre for Cardiovascular Research, Partner Site Hamburg/Kiel/Lübeck20251HamburgGermany * Correspondence: Tayyiba.azam@manchester.ac.uk Received: 12 June 2023 Accepted: 9 August 2023 Published: 27 December 2023 Abstract: Since its emergence as a cardiovascular epidemic in 1997, heart failure (HF) continues to be a significant challenge globally both economically and in clinical practice. As a consequence of the lack of effective treatments available, significant efforts have been devoted with the aim of identifying novel therapeutic strategies to treat HF. Loss of Mitogen-activated Protein Kinase Kinase 7 (MKK7) in the myocardium has previously been shown to underpin ventricular hypertrophy and HF progression. We demonstrated that adeno-associated virus 9 (AAV9) cardiac-specific overexpression of MKK7 therapeutically impeded cardiac dysfunction, interstitial fibrosis and cardiomyocytes apoptosis following 5-weeks pressure overload-induced HF. It was found that this was achieved, at least partly, by ameliorating Endoplasmic Reticulum (ER) stress. Mechanistically, in vivo and in vitro analysis revealed that although overexpression of MKK7 had no effect on PERK-ATF4 or ATF6 signalling pathways, the IRE1-XBP1 signalling pathway was preserved and a hindered increase in CHOP expression was observed. In conclusion, overexpression of MKK7 holds therapeutic potential in mitigating the pathological cardiac changes associated with HF progression.

Abstract 14924: SM22-Cre-Mediated SOCS3 Deficient Mice Exhibit Pericardial Fibrosis, Diastolic Dysfunction, and Increased Mortality Rates Due to Augmented Activation of STAT3 in Fibroblasts

Background: Suppressor of cytokine signaling-3 (SOCS3) is a cytokine-inducible potent negative regulator of STAT3 signaling pathway. Here, we aimed to determine whether SOCS3 in non-cardiomyocytes would play a role in cardiovascular pathophysiology. Methods and Results: To investigate the role of SOCS3 in non-cardiomyocytes, we generated conditional knockout mice by crossing SOCS3-flox mice with SM22-α-Cre mice (SM22-SOCS3-KO mice). Mortality rates in the SM22-SOCS3-KO mice was significantly higher than that in the wild-type mice (WT). Heart weight to body weight ratio was significantly increased in SM22-SOCS3-KO mice compared with WT at 12 months of age. Echocardiographic analyses revealed that SM22-SOCS3-KO mice showed significantly increased left ventricular diastolic dysfunction compared with WT from 12 months of age. Sirius-red staining revealed that thickness of pericardium and cardiac interstitial fibrosis in SM22-SOCS3-KO mice were markedly greater compared with WT mice at 12 months of age. Western blot analyses showed that phosphorylated STAT3 was significantly increased in SM22-SOCS3-KO hearts compared with WT mice at 12 months of age. PCR array analysis revealed that the expression of pro-fibrotic ctgf , pdgf , and TGF-beta family genes including tgf-beta1 , tgf-beta2 , and tgf-beta3 , were significantly higher in SM22-SOCS3-KO hearts than those in WT at 6 months of age. We also found that circulating interleukin-6 concentration was significantly higher in SM22-SOCS3-KO mice compared with WT mice at 12 months of age. After interleukin-6 administration, in the heart tissue from SM22-SOCS3-KO mice, coimmunostaining of phosphorylated STAT3 and ER-TR7 revealed that STAT3 activation occurred in fibroblasts in the coronary arterial adventitia and pericardium. Conclusion: Thus, SM22-Cre-mediated SOCS3 deletion induces higher mortality rates, increased pericardial fibrosis, cardiac interstitial fibrosis, and increased diastolic dysfunction in aging mice, possibly through the increased activation of STAT3 in fibroblasts.

Abstract 15205: miR-132 Inhibition Improves Myocardial Strain in a Large Animal Model of Chronic Adverse Remodeling

Background: MicroRNAs (miRNAs) are transcriptional regulators and essential drivers of heart failure (HF). The miR-132 is necessary and sufficient to progress adverse cardiac remodeling. The strong effects are exhibited by, amongst others, cardiomyocyte hypertrophy and calcium signaling impairment. Treatments directly targeting the roots of the disease are scarce, but miR-132 inhibition by CDR132L, a rationally designed synthetic oligonucleotide, significantly improves cardiac dysfunction in HF early after myocardial infarction (MI). Rational: The aim of the current study was to gain further data on myocardial function and efficacy of CDR132L by analyzing left ventricular (LV) and atrial (LA) wall motion by serial cardiac magnetic resonance (cMRI) strain imaging in a clinically relevant large animal (pig) model of chronic HF. Methods and Results: Mangalica pigs (n=15) were randomized 1-month post-MI, initiated by left anterior descending artery occlusion followed by reperfusion as a chronic model of post-MI HF. Animals received CDR132L over 5 months by monthly intravenous treatments with 5 mg/kg. LV and LA strain parameters were deteriorated after MI over time but significantly ameliorated by CDR132L treatment, compared to placebo. Strain parameters showed significant correlations with pharmacodynamic measures such as left-ventricular ejection fraction, NT-proBNP and cardiac interstitial fibrosis in remodeling hearts 6 months post-MI. Conclusions: LV and LA motion and contractility were improved by repeated dosing of CDR132L with monthly frequency in a large animal model of chronic post-MI HF. The results highlight the translational value and usability of MRI-based cardiac strain imaging in HF drug development and support further clinical development of CDR132L.

Abstract 17132: IRE1α Protects Against Cardiac Fibrosis via Regulating Selective Transcript Degradation

Background: Upon cardiac injury, cardiac fibroblasts become activated and differentiate intomyofibroblasts to maintain cardiac structure and function through secretion of stabilizingextracellular matrix (ECM) components. However, if this persists, it leads to stiffening of themyocardium and heart failure. The unfolded protein response (UPR) responds to an increaseddemand for folding of nascent secreted ECM proteins trafficked through the endoplasmicreticulum such as collagen. IRE1α, the most evolutionarily conserved arm of the UPR, actsadaptively both by enhancing protein folding of secreted proteins and reducing prolongedincreases in protein synthesis as occurs during pathologic cardiac fibrosis. Hypothesis: IRE1α protects against cardiac fibrosis via inhibiting pathologic sustained fibroblastactivation. Methods: Primary cardiac fibroblasts (CFBs) were cultured with transforming growth factor beta(TGF-β) to promote activation, in vitro . Small molecule targeting approaches were utilized tospecifically inhibit or activate IRE1α. IRE1α-floxed mice were injected with AAV9 to knockoutIRE1α specifically in myofibroblasts (IRE1mfbKO) and were subjected to transverse aorticconstriction (TAC) as a model of heart failure to stimulate fibroblast activation, in vivo . Results: While small molecule activation of IRE1α significantly blunted CFB activation inresponse to TGF-β, specific inhibition of IRE1α’s endonuclease domain enhanced CFBresponsiveness to TGF-β. Importantly, this effect occurred independent of IRE1α’s canonicalmechanism of activating the transcription factor, XBP1, implicating regulated IRE1α-dependentdecay (RIDD) as a novel anti-fibrotic protective mechanism. Transcriptomics of CFBs identifieda novel “RIDD-ome” of pro-fibrotic mRNA targets of IRE1α-mediated degradation. Finally, inresponse to TAC, IRE1mfbKO mice exhibited an exacerbated decrease in cardiac function andmarked increase interstitial fibrosis. Conclusions: IRE1α protects against pathologic differentiation of CFBs in response to TGF-β or TACvia regulating the degradation of a novel subset of pro-fibrotic transcripts. Thus, small moleculetargeting of IRE1α represents a novel approach to mitigating cardiac fibrosis.

Abstract 15316: Neonatal Mesenchymal Stem Cells Ameliorate Cardiac Fibrosis and Diastolic Dysfunction in HFpEF via Expanding CD4 + CD25 + Foxp3 + T regs

Introduction: We have demonstrated that neonatal mesenchymal stem cells (nMSCs) extracted from human neonatal cardiac tissues and their exosomes, secretome, potently decrease cardiac fibrosis and improve cardiac function in the rat model of myocardial infarction. CD4 + CD25 + Foxp3 + (forkhead box 3) regulatory T cells (T regs ) are recently shown to regulate the formation of cardiac fibrosis in myocardial infarction. How nMSCs and secretome affect cardiac fibrosis and T regs of animals with heart failure with preserved ejection fraction (HFpEF) is unknown. Hypothesis: We hypothesized that nMSCs and secretome ameliorate cardiac fibrosis and diastolic dysfunction in HFpEF by regulating cardiac T regs . Methods: C57BL/6 mice were fed 60% high-fat diet and L-NAME to induce HFpEF or normal chow as a control. Left ventricular morphology and function were evaluated using an echocardiography. After the mice developed HFpEF, the animals were injected 10 6 nMSCs, 10 mg/kg of secretome, or equivalent amounts of vehicle as a control via tail vein. Myocardial fibrosis was quantified in trichrome-stained heart sections. Circulating and cardiac T regs were measured on a FACSCanto II cytometer. Fingolimod at a dose of 3 mg/kg was intraperitoneally injected daily for 18 days. Results: C57BL/6 mice fed high-fat diet and L-NAME for 5 weeks developed obesity, myocardial fibrosis, left ventricular hypertrophy and diastolic dysfunction (increases in mitral E/e’ ratio), and exercise intolerance with &gt; 50% of left ventricular ejection fraction. Compared to the HFpEF mice receiving vehicle, either nMSCs or secretome significantly decreased cardiac interstitial fibrosis and mitral E/e’ ratio and increased cardiac CD4 + CD25 + FoxP3 + T regs from 1 to 4 weeks post treatment. Importantly, either nMSCs or secretome enhanced the exercise speed and distance of the HFpEF mice. Fingolimod significantly decreased circulating and cardiac T regs in the HFpEF mice, which blocked the beneficial effects of nMSCs and secretome on cardiac fibrosis and diastolic function. Conclusions: nMSCs and secretome ameliorate cardiac fibrosis and diastolic dysfunction by expanding CD4 + CD25 + FoxP3 + T reg s in HFpEF. These results suggest that nMSCS and secretome have high therapeutic potential for HFpEF.

Link between fibrosis-specific biomarkers and interstitial fibrosis in hypertrophic cardiomyopathy.

Cardiac fibrosis is a hallmark of hypertrophic cardiomyopathy (HCM) and has proven unfavorable clinical significance. Replacement fibrosis is better known, and has already been studied on a larger scale, whereas interstitial fibrosis is less explored. We aimed to analyze relationship between serum biomarkers and interstitial fibrosis, as assessed with cardiac magnetic resonance (CMR) in HCM. We performed 3T CMR scans in 50 HCM patients to assess interstitial fibrosis as expressed by extracellular volume (ECV). In all patients, we determined levels of serum cardiac-specific (troponin T [TnT], N-terminal prohormone of brain natriuretic peptide [NT-proBNP]) and fibrosis-specific (procollagen I C-terminal propeptide, procollagen III N-terminal propeptide, transforming growth factor β1, galectin 3) biomarkers. Patients were divided based on their median value of ECV. The final study population consisted of 49 patients. The median value of ECV in our cohort was 28.1%. Patients stratified according to median ECV differed in terms of several variables: body mass index, late gadolinium extent, NT-proBNP and galectin 3 levels (all P < 0.05). Cardiac biomarkers (TnT and NT-proBNP) and galectin 3 were significantly correlated with ECV (rS = 0.34; P = 0.02; rS = 0.39; P = 0.006; rS = 0.43; P = 0.002, respectively). Galectin 3 and body mass index were found to be independent predictors of ECV (odds ratio [OR], 2.29 [1.07-4.91]; P = 0.03; OR, 0.81 [0.68-0.97]; P = 0.02, respectively). Galectin 3 was an independent predictor of interstitial fibrosis in HCM patients expressed as elevated ECV values. The other fibrosis-specific biomarkers measured were not useful in detecting interstitial fibrosis in HCM. In addition, there was a positive correlation between classical cardiac biomarkers and interstitial fibrosis in HCM patients.

Endothelial MICU1 alleviates diabetic cardiomyopathy by attenuating nitrative stress-mediated cardiac microvascular injury

BackgroundMyocardial microvascular injury is the key event in early diabetic heart disease. The injury of myocardial microvascular endothelial cells (CMECs) is the main cause and trigger of myocardial microvascular disease. Mitochondrial calcium homeostasis plays an important role in maintaining the normal function, survival and death of endothelial cells. Considering that mitochondrial calcium uptake 1 (MICU1) is a key molecule in mitochondrial calcium regulation, this study aimed to investigate the role of MICU1 in CMECs and explore its underlying mechanisms.MethodsTo examine the role of endothelial MICU1 in diabetic cardiomyopathy (DCM), we used endothelial-specific MICU1ecKO mice to establish a diabetic mouse model and evaluate the cardiac function. In addition, MICU1 overexpression was conducted by injecting adeno-associated virus 9 carrying MICU1 (AAV9-MICU1). Transcriptome sequencing technology was used to explore underlying molecular mechanisms.ResultsHere, we found that MICU1 expression is decreased in CMECs of diabetic mice. Moreover, we demonstrated that endothelial cell MICU1 knockout exacerbated the levels of cardiac hypertrophy and interstitial myocardial fibrosis and led to a further reduction in left ventricular function in diabetic mice. Notably, we found that AAV9-MICU1 specifically upregulated the expression of MICU1 in CMECs of diabetic mice, which inhibited nitrification stress, inflammatory reaction, and apoptosis of the CMECs, ameliorated myocardial hypertrophy and fibrosis, and promoted cardiac function. Further mechanistic analysis suggested that MICU1 deficiency result in excessive mitochondrial calcium uptake and homeostasis imbalance which caused nitrification stress-induced endothelial damage and inflammation that disrupted myocardial microvascular endothelial barrier function and ultimately promoted DCM progression.ConclusionsOur findings demonstrate that MICU1 expression was downregulated in the CMECs of diabetic mice. Overexpression of endothelial MICU1 reduced nitrification stress induced apoptosis and inflammation by inhibiting mitochondrial calcium uptake, which improved myocardial microvascular function and inhibited DCM progression. Our findings suggest that endothelial MICU1 is a molecular intervention target for the potential treatment of DCM.

Differential Role of Aldosterone and Transforming Growth Factor Beta-1 in Cardiac Remodeling.

Angiotensin II, a major culprit in cardiovascular disease, activates mediators that are also involved in pathological cardiac remodeling. In this context, we aimed at investigating the effects of two of them: aldosterone (Ald) and transforming growth factor beta-1 (TGF-β1) in an in vivo model. Six-week-old male wild-type (WT) and TGF-β1-overexpressing transgenic (TGF-β1-TG) mice were infused with subhypertensive doses of Ald for 2 weeks and/or treated orally with eplerenone from postnatal day 21. Thehearts' ventricles were examined by morphometry, immunoblotting to assess the intracellular signaling pathways and RT qPCR to determine hypertrophy and fibrosis marker genes. The TGF-β1-TG mice spontaneously developed cardiac hypertrophy and interstitial fibrosis and exhibited a higher baseline phosphorylation of p44/42 and p38 kinases, fibronectin and ANP mRNA expression. Ald induced a comparable increase in the ventricular-heart-weight-to-body-weight ratio and cardiomyocyte diameter in both strains, but a less pronounced increase in interstitial fibrosis in the transgenic compared to the WT mice (23.6% vs. 80.9%, p < 0.005). Ald increased the phosphorylation of p44/42 and p38 in the WT but not the TGF-β1-TG mice. While the eplerenone-enriched chow partially prevented Ald-induced cardiac hypertrophy in both genotypes and interstitial fibrosis in the WT controls, it completely protected against additional fibrosis in transgenic mice. Ald appears to induce cardiac hypertrophy independently of TGF-β1, while in the case of fibrosis, the downstream signaling pathways of these two factors probably converge.

PHB2 ameliorates Doxorubicin-induced cardiomyopathy through interaction with NDUFV2 and restoration of mitochondrial complex I function

BackgroundDoxorubicin (DOX) is among the most widely employed antitumor agents, although its clinical applications have been largely hindered by severe cardiotoxicity. Earlier studies described an essential role of mitochondrial injury in the pathogenesis of DOX cardiomyopathy. PHB2 (Prohibitin 2) is perceived as an essential regulator for mitochondrial dynamics and oxidative phosphorylation (OXPHOS) although its involvement in DOX cardiomyopathy remains elusive. MethodsTo decipher the possible role of PHB2 in DOX cardiomyopathy, tamoxifen-induced cardiac-specific PHB2 conditional knockout mice were generated and subjected to DOX challenge. Cardiac function and mitochondrial profiles were examined. Screening of downstream mediators of PHB2 was performed using proteomic profiling and bioinformatic analysis, and was further verified using co-immunoprecipitation and pulldown assays. ResultsOur data revealed significantly downregulated PHB2 expression in DOX-challenged mouse hearts. PHB2CKO mice were more susceptible to DOX cardiotoxicity compared with PHB2flox/flox mice, as evidenced by more pronounced cardiac atrophy, interstitial fibrosis and decrease in left ventricular ejection fraction and fractional shortening. Mechanistically, PHB2 deficiency resulted in the impairment of mitochondrial bioenergetics and oxidative phosphorylation in DOX cardiotoxicity. Proteomic profiling and interactome analyses revealed that PHB2 interacted with NDUFV2 (NADH-ubiquinone oxidoreductase core subunit V2), a key subunit of mitochondrial respiratory Complex I to mediate regulatory property of PHB2 on mitochondrial metabolism. PHB2 governed the expression of NDUFV2 by promoting its stabilization, while PHB2 deficiency significantly downregulated NDUFV2 in DOX-challenged hearts. Cardiac overexpression of PHB2 alleviated mitochondrial defects in DOX cardiomyopathy both in vivo and in vitro. ConclusionsOur study defined a novel role for PHB2 in mitochondrial dynamics and energetic metabolism through interacting with NDUFV2 in DOX-challenged hearts. Forced overexpression of PHB2 may be considered a promising therapeutic approach for patients with DOX cardiomyopathy.

Cyclosporine A induces cardiac remodeling through TGF-β/Smad3/miR-29 signaling pathway and alters gene expression of miR-30b-5p/CaMKIIδ isoforms pathways: alleviating effects of moderate exercise.

Cyclosporine A (CsA)-induced cardiac interstitial fibrosis and cardiac hypertrophy are highly known phenomena; however, the basic mechanisms of CsA cardiotoxicity are unclear. The present study evaluated the role of the Transforming growth factor-beta (TGF-β)/Smad3/miR-29b signaling pathway and CaMKIIδ isoforms gene expression in cardiac remodeling under CsA exposure alone or combined with moderate exercise. A total of 24 male Wistar rats were divided into control, cyclosporine (30mg/kg BW), and cyclosporine-exercise groups. After 42 days of treatment, the findings revealed a significant decline in miR-29 and miR-30b-5p gene expression and an increase in gene expression of Smad3, calcium/calmodulin-dependent protein kinaseIIδ (CaMKIIδ) isoforms, Matrix Metalloproteinases (MMPs), protein expression of TGF-β, heart tissue protein carbonyl and oxidized LDL (Ox-LDL), and plasma LDL and cholesterol levels in the CsA-treated group compared to the control group. The CsA group presented greater histological heart changes such as fibrosis, necrosis, hemorrhage, infiltrated leukocyte, and left ventricular weight/heart weight than the control group. Moreover, combined moderate exercise and CsA relatively improved gene expression changes and histological alternations compared to the CsA group. TGF-β-Smad3-miR-29 and CaMKIIδ isoforms may mainly contribute to the progression of heart fibrosis and hypertrophy due to CsA exposure, providing new insight into the pathogenesis and treatment of CsA-induced side effects on the heart tissue.

Osteopontin Is an Integral Mediator of Cardiac Interstitial Fibrosis in Models of Human Immunodeficiency Virus Infection.

People with human immunodeficiency virus (HIV) have heightened incidence/risk of diastolic dysfunction and heart failure. Women with HIV have elevated cardiac fibrosis, and plasma osteopontin (Opn) is correlated to cardiac pathology. Therefore, this study provides mechanistic insight into the relationship between osteopontin and cardiac fibrosis during HIV infection. Mouse embryonic fibroblasts (MEFs) modeled cardiac fibroblasts in vitro. Simian immunodeficiency virus (SIV)-infected macaques with or without antiretroviral therapy and HIV-infected humanized mice modeled HIV-associated cardiac fibrosis. Lipopolysaccharide-stimulated MEFs were myofibroblast-like, secreted cytokines, and produced Opn transcripts. SIV-infected animals had elevated plasma Opn at necropsy, full-length Opn in the ventricle, and ventricular interstitial fibrosis. Regression modeling identified growth differentiation factor 15, CD14+CD16+ monocytes, and CD163 expression on CD14+CD16+ monocytes as independent predictors of plasma Opn during SIV infection. HIV-infected humanized mice showed increased interstitial fibrosis compared to uninfected/untreated animals, and systemic inhibition of osteopontin by RNA aptamer reduced left ventricle fibrosis in HIV-infected humanized mice. Since Opn is elevated in the plasma and left ventricle during SIV infection and systemic inhibition of Opn reduced cardiac fibrosis in HIV-infected mice, Opn may be a potential target for adjunctive therapies to reduce cardiac fibrosis in people with HIV.

Abstract 363: Resident Vascular Adventitial Progenitor Cells Of Smooth Muscle Cell-lineage Adopt Profibrotic Phenotype And Contribute To Cardiac Fibrosis.

Cardiac myofibroblasts are the major contributors to ECM deposition in pathological cardiovascular fibrosis, which is the characteristic feature of cardiovascular diseases. However, due to potential heterogeneity of myofibroblasts, the origin of these cells remains controversial. Using highly specific smooth muscle cell lineage-tracing mouse models, we discovered the smooth muscle cell origin of a subpopulation of resident vascular adventitial progenitor cells, defined by the expression of the stem cell marker Sca1 (AdvSca1-SM cells), which rapidly proliferate and adopt a myofibroblast phenotype in response to acute vascular injury. Further, we identified a specific gene signature of active hedgehog/Wnt/β-catenin/Klf4 signaling in AdvSca1-SM cells and validated a Gli1-CreERT2-ROSA26-YFP (Gli1) reporter mouse model to be a faithful lineage tracing system for AdvSca1-SM cells. However, the function of AdvSca1-SM cells in cardiac fibrosis is unknown. Using immunofluorescent staining and label-free second harmonic generation (SHG) imaging, we observed the expansion and migration of AdvSca1-SM cells in close association with perivascular and interstitial cardiac fibrosis in pressure overload-induced cardiac fibrosis in Gli1 reporter mice. By integrating single cell RNA sequencing (scRNA-seq) with spatial transcriptomics, we identified a AngII-driven spatiotemporal profibrotic differentiation trajectory of AdvSca1-SM cells in mouse cardiac tissue. The trajectory, characterized by loss of expression of stemness genes, such as Klf4 , the lncRNA, Meg3 , and up-regulation of myofibroblast genes, was recapitulated in human RNA-seq data and of translational significance. Connectivity map analysis of the scRNA-seq data identified statins as potential candidates for inhibition of the profibrotic transition of AdvSca1-SM cells. In agreement, simvastatin induced the expression of stemness genes and inhibited TGFβ-induced up-regulation of αSMA and down-regulation of KLF4 in cultured AdvSca1-SM cells. Lentiviral-mediated up-regulation of Meg3 also rescued TGFβ-induced suppression of stemness genes. Our findings support the further development of anti-fibrotic therapeutics targeting AdcSca1-SM cells.

Impact of IH-induced sympathetic hyperactivity and metabolic dysfunctions on ischemic cardiomyopathy progression

Patients with obstructive sleep apnea (OSA) exhibit poor prognosis after myocardial infarction (MI). Intermittent hypoxia (IH), the hallmark feature of OSA, promotes sympathetic hyperactivity and systemic insulin resistance, and has been identified as a major contributor to post-MI cardiac remodeling and contractile dysfunction. We hypothesize that sympathetic hyperactivity and metabolic alterations induced by IH promote desensitization of cardiac adrenergic and insulin pathways via activation of G protein-coupled receptors (GRK2), and subsequently participate in the aggravation of ischemic cardiomyopathy. MI is induced in C57bl6 mice by permanent ligation of the left coronary artery (MI). Mice are then randomized to IH (21–5% FiO2, 60 s cycle, 8 h/day) or normoxia for up to 6 weeks. After two weeks, mice are treated with a GRK2 inhibitor, Paroxetine (5 mg/kg/d), or 25% DMSO (Alzet® pumps). Longitudinal follow-up of mice includes evaluation of sympathetic activity (spectral analysis of heart rate variability (HRV), systemic insulin sensitivity (dynamic insulin tolerance test) and determination of cardiac function/remodeling (echocardiography). At the end of the protocol, cardiac interstitial fibrosis and hypertrophy are evaluated by RT-qPCR and histology (Sirius Red and WGA staining, respectively). Assessment of insulin signaling pathway is performed by Western blot. IH induces sympathetic hyperactivity in MI mice, demonstrated by a modification of the sympathovagal balance (LF increase). Paroxetine treatment abolishes the increase in LF in MI-IH condition and restores mRNA expression of β1 and β2 adrenergic receptors. MI-IH induces systemic insulin resistance compared to MI-N condition, which is prevented by Paroxetine treatment. In addition, Paroxetine treatment improves insulin signaling in the liver of MI-IH mice (pIRβ and pAKT). IH exacerbates cardiac interstitial fibrosis and worsens contractile dysfunction in MI mice, resulting in a significant decrease in ejection fraction (19.4 ± 2.1% vs. 29.9 ± 3.6% in IH vs. N respectively, P < 0.05). The effect of paroxetine on cardiac remodeling and function is currently being analyzed. These findings demonstrate that IH induces cardiac sympathetic hyperactivity and insulin resistance, which could contribute to the worsening of ischemic heart disease via GRK2.

Immobilizing Interstitial Cardiac Fibrosis

The alterations in the endomysium and perimysium might cause compaction and gradual mechanical compression of cardiomyocytes resulting in their immobilization. This process finally leads to severe stiffening, so that the newly formed frame around individual cardiomyocytes and their clusters hinders normal diastole, and later systole. This phenomenon is referred to as immobilizing interstitial cardiac fibrosis (IICF). Deciphering the molecular and structural elements of myocardial changes is the key to understanding the pathogenetic foundations of heart failure development. The study included 69 patients. Group I (n = 32) included patients with IICF; group II (n = 37) was comparison group. We evaluated the clinical picture, anamnesis of the disease, the results of physical examination, laboratory and instrumental examination of patients and autopsy data. In the anamnesis, patients with IICF were more likely to have diseases than patients in the control group: arrhythmia and impaired conductivity (88% vs. 19%, odds ratio (OR): 30.0; 95% confidence interval (CI): 7.918 - 113.7, P < 0.001), systemic connective tissue diseases (78% vs. 5%, OR: 62.5; 95% CI: 11.9 - 326.5, P < 0.001), viral infections (including severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)) (53% vs. 19%, OR: 4.86; 95% CI: 1.66 - 14.25, P = 0.003), type 2 diabetes mellitus (47% vs. 8%, OR: 10.0; 95% CI: 2.54 - 39.34, P < 0.001), radiation therapy for mediastinal lymphoma and other oncological diseases (19% vs. 0%, P = 0.008), focal infections (sinusitis, osteomyelitis, periodontitis, nephritis, cystitis, pyelonephritis, pleurisy, etc.) within 12 months (31% vs. 11%, P = 0.069), chronic kidney disease (25% vs. 8%, P = 0.097), and tuberculosis (9% vs. 0%, P = 0.095). We have identified a statistically significant difference between the groups: the volume of the fibrosis zone (17.5±9.2% vs. 4.9±2.3%, P = 0.001), the expression of type I collagen (5,182 ± 1,301 vs. 2,189 ± 754 in 1 mm2, P = 0.0001), type III collagen (7,562 ± 1,405 vs. 2,320 ± 541 in 1 mm2, P = 0.0001), matrix metalloproteinase (MMP)-2 (12,850 ± 6,200 vs. 9,501 ± 7,145 in 1 mm2, P = 0.005), MMP-9 (15,745 ± 5,695 vs. 6,920 ± 3,125 in 1 mm2, P = 0.0001), connexin-43 (25,689 ± 14,871 vs. 37,523 ± 12,561 in 1 mm2, P = 0.001), fibronectin (3,448 ± 720 vs. 1,544 ± 610 in 1 mm2, P = 0.0001), and transforming growth factor β (TGF-β) (5,121 ± 1,243 vs. 2,531 ± 1,489 in 1 mm2, P = 0.001). IICF is a separate pathological condition and one of the main causes of chronic heart failure. It is induced by changes in the myocardial connective tissue that prevent normal functioning of the myocardium.

Sodium glucose co-transporter 2 inhibition with empagliflozin on metabolic, cardiac and renal outcomes in recent cardiac transplant recipients (EMPA-HTx): protocol for a randomised controlled trial

IntroductionCardiac transplantation (CTx) is a life-saving operation that can improve the quality and length of a recipient’s life. Immunosuppression medication, required to prevent rejection, can result in adverse metabolic and...

Association of cardiac troponin T and growth differentiation factor 15 with replacement and interstitial cardiac fibrosis in community dwelling adults: The multi-ethnic study of atherosclerosis.

Subclinical abnormalities in myocardial structure (stage B heart failure) may be identified by cardiac and non-organ specific biomarkers. The associations of high-sensitivity cardiac troponin T (hs-cTnT) and growth differentiation factor-15 (GDF-15) with cardiac magnetic resonance imaging (CMR) interstitial fibrosis (extracellular volume [ECV]) is unknown and for GDF-15 the association with replacement (late gadolinium enhancement [LGE]) is also unknown. GDF-15 is a systemic biomarker also released by myocytes associated with fibrosis and inflammation. We sought to define the associations of hs-cTnT and GDF-15 with these CMR fibrosis measures in the MESA cohort. We measured hs-cTnT and GDF-15 in MESA participants free of cardiovascular disease at exam 5. CMR measurements were complete in 1737 for LGE and 1258 for ECV assessment. We estimated the association of each biomarker with LGE and increased ECV (4th quartile) using logistic regression, adjusted for demographics and risk factors. Mean age of the participants was 68 ± 9 years. Unadjusted, both biomarkers were associated with LGE, but after adjustment only hs-cTnT concentrations remained significant (4th vs. 1st quartile OR] 7.5, 95% CI: 2.1, 26.6). For interstitial fibrosis both biomarkers were associated with 4th quartile ECV, but the association was attenuated compared to replacement fibrosis. After adjustment, only hs-cTnT concentrations remained significant (1st to 4th quartile OR 1.7, 95%CI: 1.1, 2.8). Our findings identify that both interstitial and replacement fibrosis are associated with myocyte cell death/injury, but GDF-15 a non-organ specific biomarker prognostic for incident cardiovascular disease is not associated with preclinical evidence of cardiac fibrosis.