Myocardial Interstitial Fibrosis Research Articles

Abstract 4131128: Cardiomyocyte-specific Deletion of Creg1 Impairs Autophagy and Leads to Age-dependent Dilated Cardiomyopathy

CREG1 is a small glycoprotein predominantly localized in the endolysosomal system. In mouse heart, CREG1 expression increases with age. We previously observed cardiac hypertrophy and ventricular non-compaction in a small percentage of constitutive Creg1 knockout mice during the neonatal stage. To elucidate the physiological function of CREG1 in the heart, we generated cardiomyocyte-specific Creg1 knockout (cm Creg1 KO) and knock-in (cm CREG1 KI) mice by crossing Creg1 fl/fl and Rosa hCREG1/hCREG1 with Myh6-Cre mice, respectively. By 6 months of age, the cm Creg1 KO mice developed severe myocardial interstitial fibrosis. Echocardiography at 10 months revealed markedly dilated left ventricles and significantly reduced ejection fractions. All the cm Creg1 KO mice succumbed to heart failure between 10-12 months, while Creg1 fl/fl control littermates exhibited no obvious cardiac abnormalities. Necropsy of deceased cm Creg1 KO mice showed increased heart-to-body weight ratios, enlarged cardiac chambers, and left atrial thromboses. Electron microscopy revealed sparse and elongated myofibers, scant and bizarre-shaped mitochondria, empty cytoplasm, and increased interstitial collagen accumulation. The cm CREG1 KI mice exhibited better endurance to nutritional deprivation than Rosa hCREG1/hCREG1 littermate controls. In sharp contrast to cm Creg1 KO hearts, cm CREG1 KI and Rosa hCREG1/hCREG1 control hearts displayed very mild fibrosis at 8 months, suggesting that CREG1 overexpression may confer cardioprotective effects. In cultured cardiomyocytes, CREG1 colocalizes with the autophagosome marker LC3B following serum deprivation. Immunofluorescence microscopy demonstrated a marked reduction of LC3B puncta in cm Creg1 KO hearts. Analysis of autophagic flux using CAG-RFP-EGFP-LC3 transgenic mice and immunoblotting indicated that the absence of CREG1 impairs both autophagosome formation and degradation, whereas knock-in of CREG1 enhances these autophagic processes. These findings suggest that CREG1 promotes autophagy and protects the heart from age-dependent dilated cardiomyopathy.

Neuroimmune cross-talk in heart failure.

Heart failure (HF) is characterized by autonomic nervous system (ANS) imbalance and low-grade chronic inflammation. The bidirectional relationship between the ANS and immune system (IS) is named "neuroimmune cross-talk" (NICT), and is based on common signaling molecules, receptors, and pathways. NICT may be altered in HF, and neuroinflammation seems to be a main driver of HF progression. In HF, heightened sympathetic nerve activity triggers inflammatory cascades that lead to cardiomyocyte death and myocardial interstitial fibrosis. Concurrently, parasympathetic withdrawal may impair the cholinergic anti-inflammatory pathway, with a less effective immune response to infections or inflammatory events. Additionally, microglial activation and inflammatory molecules contribute to autonomic imbalance by acting on central nuclei and peripheral visceral feedbacks, which in turn promote adverse cardiac remodeling, HF decompensation, and potentially life-threatening arrhythmias. Therefore, neuroinflammation has been identified as a potential target for treatment. Pharmacological antagonism of the neurohormonal system remains the cornerstone of chronic HF therapy. While some drugs used in HF management may have additional benefits due to their anti-inflammatory properties, clinical trials targeting inflammation in patients with HF have so far produced inconclusive results. Nevertheless, considering the pathophysiological relevance of NICT, its modulation seems an appealing strategy to optimize HF management. Current research is therefore investigating novel pharmacological targets for anti-inflammatory drugs, and the immunomodulatory properties of denervation approaches and bioelectronic medicine devices targeting NICT and neuroinflammation in HF. A deeper understanding of the complex relationship between the ANS and IS, as outlined in this review, could therefore facilitate the design of future studies aimed at improving outcomes by targeting NICT in patients with HF.

The development of small-molecule ERBB4 agonists as a treatment for heart failure

Abstract The neuregulin-1 (NRG1)/ERBB4 signaling pathway has emerged as a cardioprotective pathway and is a promising target for the treatment of chronic heart failure. Activation of ERBB4 signaling is known to decrease cardiomyocyte cell death and hypertrophy, and fibroblast collagen synthesis. Recombinant NRG1 (rNRG1) is currently tested in phase III clinical trials for heart failure, but its need for intravenous administration is a disadvantage. In an attempt to circumvent this, we hypothesized that small-molecule-induced activation of ERBB4 is feasible and would recapitulate the effects of its natural ligand on myocytes and fibroblasts. To this end, we screened 10,240 compounds for their ability to induce homodimerization of ERBB4. We identified a series of 8 similar compounds (named EF-1 – EF-8) that concentration-dependently induced ERBB4 dimerization, with EF-1 being the most potent and effective compound (n = 4-5 independent repeats in each group; Emax = 27.9 ± 4.8% relative to NRG1, EC50 = 10.5 ± 4.5 x 10-6). EF-1 showed neither cytotoxicity nor increased cell proliferation of tumor cell lines. In vitro, EF-1 significantly decreased in a concentration-dependent manner hydrogen peroxide–induced cardiomyocyte cell death (n = 4 independent repeats in each group; P<0.0001 compared to siERBB4, Fig. 1A), angiotensin-II (AngII)-induced cardiomyocyte hypertrophy (n = 20 individual cardiomyocytes in each group; P<0.0001 compared to AngII/vehicle, Fig. 1B), and collagen expression in cultured human fibroblasts (n = 3 independent repeats in each group; P=0.03 compared to siERBB4, Fig. 1C). The observed effects in cultured cardiomyocytes and fibroblasts could be abrogated by siRNA targeting ERBB4, indicating that they were mediated by ERBB4. Moreover, when used in vivo, EF-1 (2 mg/kg/day) significantly decreased AngII-induced left ventricular Col1a1 and Col3a1 mRNA expression (n = 4-5 mice in each group; P=0.02 and P=0.004 compared to AngII/vehicle, respectively) and inhibited AngII-induced myocardial total and interstitial fibrosis in wild-type mice (n = 4-5 mice in each group, Fig. 2), but not in Erbb4-null mice. Moreover, EF-1 decreased acute cardiotoxicity (assessed by troponin release) in wild-type mice treated with doxorubicin (DOX; n = 8-9 mice in each group; P<0.0001 compared to DOX/vehicle), but not in Erbb4-null mice. In conclusion, we show that small-molecule-induced ERBB4 dimerization and activation is feasible, and recapitulates anti-fibrotic and cardiomyocyte protective effects in the heart in an ERBB4-dependent manner, both in vitro and in vivo. This could be the start for the further development of small-molecule ERBB4 agonists as a novel class of drugs to treat heart failure. Cardiomyocyte-protective effect in vitroAnti-fibrotic effect in vivo

Serial quantitative stress perfusion cardiac magnetic resonance in patients undergoing coronary artery bypass grafting; prediction of symptomatic benefit

Abstract Background Serial multiparametric cardiovascular magnetic resonance (CMR) in patients undergoing coronary artery bypass grafting (CABG) may provide mechanistic insight into dynamic and persistent abnormalities of the myocardium in patients with stable coronary artery disease (CAD). Objectives To assess for dynamic CMR markers of myocardial hypoperfusion and cardiac remodelling in patients undergoing CABG. Methods Patients with CAD awaiting elective CABG were recruited into an observational cohort study. Baseline evaluation included bloods, Seattle Angina Questionnaire-7, and adenosine stress perfusion CMR. Automated fully quantitative stress and rest myocardial blood flow was calculated, alongside assessment of the visual ischaemic burden. Native and post-contrast septal T1 indices were also measured. Repeat evaluation at 6-12 months post CABG was performed. Results Of 43 patients who underwent serial evaluation with CMR (mean age 62.1±9.3, median LVEF 68% [IQR: 62-73%]), there was improvement in the median visual ischaemic burden (18% [IQR: 11-21] vs 42% [IQR: 27-51], P<0.001), mean global stress myocardial blood flow (1.5±0.5 ml/min/g vs 1.3±0.5 ml/min/g, P=0.002) and median global myocardial perfusion reserve (2.4 [IQR: 1.7-2.8] vs 1.7 [IQR: 1.4-2.2], P=0.002) following CABG. Greater improvement in the SAQ-7 summary score was associated with a larger visual ischaemic burden at baseline (ρ=0.44, P=0.004) and a greater decrease in the visual ischaemic burden following CABG (ρ=-0.38, P=0.02). Quantitative MBF metrics did not associate with baseline or change in SAQ-7 summary score. Mean LV extracellular matrix volume decreased following CABG (16.6±3.6ml/m2 vs 18.2±4.6ml/m2, P=0.009). Conclusion Multiparametric CMR identifies dynamic changes in markers of myocardial perfusion and interstitial fibrosis in patients following CABG. Visual assessment of inducible myocardial hypoperfusion may identify patients who will derive the most symptomatic benefit from CABG. The results, however, suggest an important degree of residual inducible ischaemia and an unclear clinical role for CMR-derived MBF calculations.Serial CMR perfusion dataAssociation of SAQ with perfusion

Postoperative assessment of interstitial myocardial fibrosis in aortic valve pathologies: insights from a cardiac magnetic resonance study

Abstract Background Data on the characteristics of diffuse myocardial fibrosis (DMF) among patient undergoing valve surgery for aortic regurgitation (AR), high-gradient aortic stenosis (HG-AS), and low-flow low-gradient aortic stenosis with low ejection fraction (LFLG-AS) are limited. Purpose To assess the postoperative characteristics of DMF and to compare post- and pre-operative cardiac magnetic resonance imaging (CMR) data. Methods Patients diagnosed with AR (38), HG-AS (62), and LFLG-AS (39), who met criteria for surgical intervention, were prospectively included. Pseudo-severe AS was excluded. Post-operative CMR was performed 6 to 8 months after surgery, and a comparison between post- and pre-operative data was made (delta=Δ). Quantitative analysis included assessment of extracellular volume fraction (ECV), indexed ECV (iECV), and myocardial mass (MM). Results There were differences in baseline characteristics among patients with AR, HG-AS, and LFLG-AS concerning age (54±14 vs 63±8 vs 67±8 years, respectively; p<0.01), male gender (75% vs 50% vs 82%, respectively; p<0.01), NYHA functional class III and IV (37.5% vs 55.2% vs 30.8%, respectively; p=0.03), EuroSCORE II (1.16±0.5 vs 1.26±0.46 vs 3.39±2.65%, respectively; p<0.01), and STS (0.74±0.29 vs 1.11±0.5 vs 3.21±2.11%, respectively; p<0.01). Global ECV was similar between groups (29.2±5.6 vs 27.0±3.6 vs 29.4±5.9%, respectively; p=0.01), MM was different between groups (215±76 vs 161±51 vs 203±51g, respectively; p<0.01), and iECV was different between groups and significantly higher in AS patients (50.1±31.0 vs 21±8 vs 34.2±10.2ml/m², respectively; p<0.01). All patients underwent valve surgery and there were differences regarding extracorporeal circulation time (94±25 vs 97±20 vs 75±41min, respectively; p<0.01), and 30-day mortality (0% vs 3% vs 15%, respectively; p<0.01). Post-surgery data from patients with AR (32), HG-AS (62), and LFLG-AS (21) demonstrated a comparable decrease across all groups concerning preoperative MM (ΔMM: -39.3±41.5 vs -33.4±30.9 vs -23.4±34.2g, respectively; p=0.36) (Figure 1). In contrast, iECV decreased post-surgery only in AR, remaining stable in HG-AS and LFLG-AS (ΔiECV: -19.1±22.5 vs -1.4±7.4 vs 0.9±12ml/m², respectively; p<0.01). Thus, postoperative ECV maintained commensurate values in AR, while increasing in HG-AS and LFLG-AS (ΔECV: -0.1±4.5 vs 1.5±5.1 vs 2.9±4.9%, respectively; p=0.09). Δ left ventricular ejection fraction (LVEF) was similar across groups (ΔLVEF: -1.5±10.6 vs 1.1±11.7 vs 2.6±16%, respectively; p=0.44). Conclusion In the postoperative period, a decrease in MM was observed in all groups of aortic valve pathologies. However, only patients with AR showed a simultaneous and proportional reduction in DMF mass, explaining the patterns of ECV variation. Thus, the reduction of DMF in the postoperative period appears to vary according to the phenotypes presented, and patients with AR exhibit early reverse remodeling despite having high levels of DMF.Delta iECV, LV mass and ECV measures

Comparing the anti-remodeling effect of sacubitril/valsartan and angiotensin-converting enzyme inhibition on myocardial samples of advanced heart failure patients undergoing heart transplantation

Abstract Background In decreasing heart failure (HF) hospitalization and cardiovascular death in HF patients with reduced ejection fraction, Sacubitril/Valsartan (SAC/VAL) treatment was proved to be superior to angiotensin-converting enzyme inhibition (ACEi). According to recent experimental results and clinical data based on echocardiography and circulating biomarkers, this benefit might be at least partially attributed to a greater anti-remodeling effect. However, there is a lack of direct evidence from human myocardial samples for this assumption. Purpose Therefore, we aimed to compare the anti-remodeling effect of SAC/VAL treatment to ACEi on myocardial samples of HF patients undergoing heart transplantation (HTX). Methods We studied left ventricular (LV) samples of seventy advanced HF patients who underwent HTX and received either SAC/VAL (SAC/VAL group, N=32) or ACEi treatment (ACEi group, N=38) for at least three months prior to HTX. Furthermore, all patients received beta-blockers and mineralocorticoid receptor antagonists titrated to maximally tolerated or target dose. Our groups were matched for age, sex, ejection fraction and other clinical parameters. Patients with liver or kidney failure, mechanical circulatory support, systemic inflammatory/fibrotic diseases or positive inotrope treatment were excluded. Myocardial mRNA expression of fibrotic markers and B-type natriuretic peptide (BNP) were measured with qRT-PCR and normalized to glyceraldehyde 3-phosphate dehydrogenase expression. Interstitial fibrosis area was assessed histologically. Results Preoperative plasma N-terminal pro-BNP levels were similar in the two groups (SAC/VAL: 4363±752 pg/mL vs. ACEi: 4616±1020 pg/mL; p=0.911). In contrast, the mRNA level of BNP in the myocardium was lower in patients treated with SAC/VAL (SAC/VAL: 2.2±1.05 vs. ACEi: 5.2±1.74; p=0.006). TIMP metallopeptidase inhibitor 1 (SAC/VAL: 0.07±0.01 vs. ACEi: 0.13±0.02; p=0.011), TIMP metallopeptidase inhibitor 2 (SAC/VAL: 0.06±0.01 vs. ACEi: 0.11±0.01; p<0.001), collagen type I alpha 1 chain (SAC/VAL: 0.02±0.00 vs. ACEi: 0.08±0.02; p<0.001) and collagen type III alpha 1 chain (SAC/VAL: 0.12±0.02 vs. ACEi: 0.27±0.04; p<0.001) relative gene expressions were also decreased in the LV of SAC/VAL-treated patients. Histology analysis confirmed reduced interstitial myocardial fibrosis area in the SAC/VAL group as well (SAC/VAL: 7.2±0.4% vs. ACEi: 8.6±0.5%; p=0.031). Conclusions SAC/VAL treatment decreased the myocardial expression of BNP and fibrosis-related genes to a greater extent compared with ACEi in LV samples of patients undergoing HTX. Histological analysis also verified the differences in fibrosis. Thus, the anti-remodeling effect of SAC/VAL might be superior to ACEi even in advanced HF.

Temporal dynamics of cardiac remodelling in pressure overload: the key role of visceral adipose tissue

Abstract Background Myocardial fibrosis is a prominent pathological feature of cardiac remodelling in pressure overload. The underlying mechanisms of cardiac remodelling are complex including mechanical, inflammatory and neurohormonal factors. We have recently uncovered a pathological crosstalk between visceral adipose tissue (VAT) and heart in biological aging characterized by profibrotic proteins in both the VAT secretome and the plasma contributing to myocardial interstitial fibrosis. We hypothesize that a model of pressure overload induced by transverse aortic constriction (TAC) is responsible for VAT remodelling and a VAT profibrotic secretome, which in turn worsens cardiac fibrosis and alters cardiac function. Purpose To explore the effect of pressure overload on VAT and identify a crosstalk between heart and VAT. Methods We divided wild-type male mice (5-month-old, n=10/group) into two groups: a visceral Lipectomy group and a Sham group two weeks before a moderate TAC (26G; i.e. gradient between left ventricle and aorta of 30mmHg) or a sham surgery. We sacrificed the mice at 1- and 8-week after TAC. We performed in vivo metabolic tests, echocardiography, and invasive hemodynamics, followed by ex vivo tissue analysis. We then analysed the time-course of the cardiac transcriptomic signature in TAC vs control and the impact of visceral lipectomy in both groups. Results Our results show that TAC induced not only cardiac remodelling affecting the structure and function of the heart, but also VAT fibrosis and inflammation together with activation of adrenergic receptors (Adrb3). VAT became a major source of profibrotic (TGFb and osteopontin) and proinflammatory (TNFa, IL6 and PAI1) factors as early as 1 week after TAC. Interestingly, lipectomy prevented cardiac remodelling and dysfunction. After 1 week of TAC, cardiac transcriptomic profile showed a similar upregulation of profibrotic and prohypertrophic genes in TAC groups in presence or absence of lipectomy. After 8 weeks of TAC, lipectomy prevented the upregulation of those genes and transcriptomic profile of TAC+lipectomy was similar to sham group (Figure). PCR analysis confirmed the lower expression of profibrotic (TGFb, Osteopontin), prohypertrophic (Nppa) and contractility genes (Adr1b) in TAC+Lipectomy vs TAC group after 8 weeks of TAC. Conclusion Our results suggest that VAT is detrimental to cardiac structure and function by releasing a profibrotic and a proinflammatory secretome that aggravates the cardiac remodelling induced by TAC. Conversely, lipectomy prevents the early development of TAC-induced cardiac fibrosis.

Effect of selective renal denervation guided by renal nerve stimulation on atrial remodeling

Abstract Background The renal nerves play a crucial role in regulating blood pressure (BP), and the parasympathetic nervous has been confirmed as one of the components of the renal nerves, with close connections to the central solitary nucleus. Renal nerve stimulation (RNS) can activate not only the sympathetic nerves, leading to an elevation in BP, but also the parasympathetic nerves, resulting in a reduction in BP. Multiple clinical studies have demonstrated that compared to pulmonary vein isolation (PVI), renal denervation (RDN) combined with PVI significantly increased the likelihood of freedom from atrial fibrillation, but its mechanism remains unclear. Purpose Exploring the effects of renal sympathetic denervation and renal parasympathetic denervation on atrial neural remodeling and structural remodeling from a histological perspective of atrial myocardium. Methods 24 adult healthy Kunming dogs were randomly divided into three groups: (1) RNS-guided reduced BP response sites ablation (RRA group, n=8), (2) RNS-guided elevated BP response sites ablation (ERA group, n=8), and (3) RNS only, no ablation (RSC group, n=8). Left atrial samples were obtained after a 4-week follow-up period. Results Compared to the RSC group, the ERA group showed a significant decrease in tyrosine hydroxylase (TH), while the RRA group showed a significant decrease in choline acetyltransferase (CHAT) and muscarinic acetylcholine receptor 2 (CM2) (Fig. 1A-1C). Histological results indicated that compared to the RSC group, the ERA group exhibited orderly arrangement of myocardial cells, with a significant reduction in the degree of mitochondrial swelling and a decrease in average myocardial cell area. In contrast, the RRA group showed disordered arrangement of myocardial cells, with some myofibril dissolution, noticeable swelling of cell nuclei and mitochondria, and an increase in average myocardial cell area (Fig. 1D). Further evaluation of left atrial fibrosis degree revealed that compared to the RSC group, the ERA group showed a significant decrease in Collagen I, with a reduction in interstitial fibrosis degree, while the RRA group showed a significant increase in Collagen I expression, with an increase in myocardial interstitial fibrosis degree (Fig.2). Conclusion Renal sympathetic denervation can reduce atrial sympathetic nerve, improve atrial macrostructure, ultrastructure, and fibrosis levels, which may be one of the reasons why RDN combined with PVI is more effective in maintaining sinus rhythm compared to PVI. Renal parasympathetic denervation can decrease atrial parasympathetic nerve, leading to deterioration of atrial tissue structure and exacerbation of fibrosis. This emphasizes the importance of electrical stimulation guidance during the RDN procedure to avoid "side effects" caused by renal parasympathetic nerves ablation.Figure 1Figure 2

Systemic inflammation is associated with myocardial fibrosis in patients with obstructive hypertrophic cardiomyopathy.

Chronic low-grade inflammation, often observed in hypertrophic cardiomyopathy (HCM), promotes adverse ventricular remodelling. This study aimed to investigate the relationship between inflammatory markers and myocardial fibrosis (MF) in patients with HCM. This study included 102 patients with complete baseline data who underwent septal myectomy. Myocardial samples were stained with Masson's trichrome and analysed to determine myocardial collagen content and MF levels. Plasma levels of inflammatory markers were measured using standard laboratory procedures. Univariate and multivariate logistic regression analyses were performed to explore the relationship between the inflammatory markers and MF. Among the 102 participants included in the analysis, the mean age was 48.9years, with 69 [67.6%] being men. The overall MF ranged from 2.5% to 40.7% (mean=15.2±8.1%, median=13.0%, IQR=9.9%-18.4%). Participants were divided into two groups based on a median MF of 13%. The high MF group had a larger left atrial diameter and left ventricular ejection fraction. Levels of interleukin (IL)-2, tumour necrosis factor (TNF)-α and interferon (IFN)-α were significantly higher in patients with high MF compared to those with low MF (2.3 vs. 4.0pg/mL, 3.1 vs. 3.9pg/mL, 4.2 vs.4.7pg/mL, respectively; all P<0.05). In multivariate models adjusted for age, sex and other clinical features, IL-2, IL-5 and TNF-α, were correlated with increased interstitial MF [odds ratio (OR): 1.54, 95% confidence interval (CI): 1.10-2.14; OR: 1.42, 95% CI: 1.02-1.98; OR: 1.33, 95% CI: 1.04-1.70]. After additional adjustment for imaging indicators, IL-2 and TNF-α remained significant (OR: 1.49, 95% CI: 1.06-2.09, P=0.021; OR:1.35, 95% CI: 1.01-1.80, P=0.044). The correlation analysis between inflammation and replacement fibrosis assessed by CMR in 97 patients revealed that 72 (74.2%) showed late gadolinium enhancement (LGE). No significant correlation was found between inflammatory markers and the presence or extent of LGE. Higher levels of IL-2 and TNF-α were associated with increased histopathological interstitial MF in patients with HCM. Given the gradual progression of MF in HCM, initiating anti-inflammatory treatment in the early stages may delay its progression.

The transition from hypertension to hypertensive heart disease and heart failure with preserved ejection fraction: a retrospective cross-sectional study of myocardial magnetic resonance strain and tissue characteristics.

Due to the variability of symptoms and signs associated with heart failure, along with the lack of specific tests for definitive diagnosis, the noninvasive diagnosis of heart failure with preserved ejection fraction (HFpEF) continues to pose significant clinical challenges. This investigation was designed to elucidate the clinical manifestations of HFpEF and to analyze cardiac magnetic resonance (CMR)-derived myocardial strain metrics and tissue characteristics in a cohort exhibiting HFpEF with hypertension (HFpEF-HTN). This retrospective analysis consisted of 128 patients diagnosed HFpEF-HTN, 78 individuals with hypertensive heart disease (HHD), 89 individuals with hypertension (HTN), and 60 normotensive healthy controls and was conducted from August 2021 to February 2024. All participants were recruited from The First Hospital of Lanzhou Universityand underwent laboratory examinations and 3.0 T CMR. The study compared clinical features and CMR-derived structural and functional parameters across different groups. Logistic regression was employed to determine the association between CMR parameters and HFpEF-HTN. Spearman correlation coefficient analysis was used to clarify the relationship between myocardial strain parameters and left ventricular (LV) ejection fraction and right ventricular (RV) ejection fraction. Additionally, the area under the curve (AUC) from receiver operating characteristic (ROC) analysis was used to compare the diagnostic performance of different CMR parameters for HFpEF-HTN. Patients diagnosed with (HFpEF-HTN) were characterized by an older demographic profile, a higher prevalence of smoking history, elevated systolic and diastolic blood pressure, increased levels of N-terminal pro-brain natriuretic peptide, and more advanced New York Heart Association functional class as compared to other studied groups. In terms of myocardial deformation, individuals with HFpEF-HTN exhibited pronounced impairments in both LV and RV function, as evidenced by significantly reduced longitudinal strain (LS), circumferential strain (CS), and radial strain (RS), relative to HTN, HHD, the control cohorts (all P values <0.001). Patients with HFpEF-HTN showed significantly elevated levels of late gadolinium enhancement, native T1, and extracellular volume fraction (ECV) indicative of myocardial interstitial fibrosis as compared to patients with HHD. Additionally, as compared to ECV, LV GCS emerged as a superior diagnostic indicator, demonstrating greater diagnostic accuracy in differentiating HFpEF-HTN patients from those with HHD (AUC =0.85; P<0.001). Moreover, LVEF showed a mild correlation with CMR-derived LV GLS (R=-0.43; P<0.001), LV GCS (R=-0.42; P<0.001), and LV GRS, (R=0.56; P<0.001) in all patients. Myocardial strain, T1 mapping, and ECV can be used for the quantitative evaluation of LV and RV ventricular remodeling, dysfunction, and tissue characteristics in patients with HFpEF-HTN and thus hold significant potential for the diagnosis of these patients.

Targeting SARS-CoV-2-Induced Cardiovascular Injury: Exploring the Potential of Ponatinib in Mitigating Cardiovascular Necroptosis in COVID-19.

The incidence of Coronavirus Disease 2019 (COVID-19) has increased dramatically in recent years, affecting millions of people worldwide. The primary cause of morbidity and mortality in COVID-19 patients is respiratory illness. However, the disease can also significantly impact the cardiovascular system. SARS-CoV-2, the virus responsible for COVID-19, enters cells using the angiotensin-converting enzyme 2 (ACE-2) receptor. ACE-2 is a component of the renin-angiotensin system (RAS) and plays a crucial role in regulating various pathological processes. The interaction of the virus with ACE-2 in the myocardium can lead to direct heart damage. Several mechanisms may contribute to myocardial damage in COVID-19 patients, including systemic inflammation, myocardial interstitial fibrosis, interferon-mediated immune response, exaggerated cytokine response, T-cell-mediated damage, coronary plaque instability, and hypoxia. There has been concern that ACE inhibitors (ACE-Is) and angiotensin receptor blockers (ARBs) may increase vulnerability to SARS-CoV-2 by upregulating ACE-2 expression. However, it may be advisable to continue medications for patients with underlying cardiovascular disorders. The precise mechanisms of cardiomyocyte injury in COVID-19 are not fully understood, but necroptosis appears to play a significant role. Current treatments for cardiac damage in COVID-19 patients include IL-6 blockers and antiplatelet therapy. Ponatinib, a small molecule tyrosine kinase inhibitor designed using computational and structural approaches, has shown the potential to affect cell death through its impact on tyrosine kinase activity. By reviewing studies related to ponatinib's effects on necroptosis and cell death, we propose a novel approach to potentially reduce the cardiotoxic effects of COVID-19 on cardiomyocytes. Further research is needed to fully elucidate the mechanisms of cardiac injury in COVID-19 and to develop targeted therapies to protect the heart from the devastating effects of this disease.

Chronic intermittent hypoxia triggers cardiac fibrosis: Role of epididymal white adipose tissue senescent remodeling?

Obstructive sleep apnea (OSA) is a growing health problem affecting nearly 1 billion people worldwide. The landmark feature of OSA is chronic intermittent hypoxia (CIH), accounting for multiple organ damage, including heart disease. CIH profoundly alters both visceral white adipose tissue (WAT) and heart structure and function, but little is known regarding inter-organ interaction in the context of CIH. We recently showed that visceral WAT senescence drives myocardial alterations in aged mice without CIH. Here, we aimed at investigating whether CIH induces a premature visceral WAT senescent phenotype, triggering subsequent cardiac remodeling. In a first experiment, 10-week-old C57bl6J male mice (n = 10/group) were exposed to 14 days of CIH (8 h daily, 5%-21% cyclic inspired oxygen fraction, 60 s per cycle). In a second series, mice were submitted to either epididymal WAT surgical lipectomy or sham surgery before CIH exposure. Finally, we used p53 deficient mice or Wild-type (WT) littermates, also exposed to the same CIH protocol. Epididymal WAT was assessed for fibrosis, DNA damages, oxidative stress, markers of senescence (p16, p21, and p53), and inflammation by RT-qPCR and histology, and myocardium was assessed for fibrosis and cardiomyocyte hypertrophy. CIH-induced epididymal WAT remodeling characterized by increased fibrosis, oxidative stress, DNA damage response, inflammation, and increased expression of senescent markers. CIH-induced epididymal WAT remodeling was associated with subtle and early myocardial interstitial fibrosis. Both epididymal WAT surgical lipectomy and p53 deletion prevented CIH-induced myocardial fibrosis. Short-term exposure to CIH induces epididymal WAT senescent remodeling and cardiac interstitial fibrosis, the latter being prevented by lipectomy. This finding strongly suggests visceral WAT senescence as a new target to mitigate OSA-related cardiac disorders.

Myocardial interstitial fibrosis in different cardiomyopathies as a basis of heart failure

Myocardial interstitial fibrosis (MIF) occurs in several ischemic and non-ischemic cardiomyopathies and is associated with left ventricular dysfunction and progression to heart failure (HF). MIF exists in two types &amp;ndash; reparative and reactive with different origin and molecular mechanisms. Although MIF arises mainly because of alterations in collagen turnover leading to collagen fiber accumulation, there are also qualitative changes in collagen fibers in cardiac diseases. There are several studies for cellular and molecular mechanisms and his role in cardiac function, biomarkers and potential target therapies.

Promoting Glutathione Synthesis: A Possibility for Treating Cardiomyopathy Induced by a Maternal Western Diet.

The adverse effects of a Western diet on obesity and diabetes among reproductive-aged women pose a significant threat to the cardiovascular health of their offspring. Given the crucial role of glutathione metabolism and glutathione-related antioxidant defense systems in cardiovascular diseases through scavenging ROS and maintaining redox homeostasis, further exploration of their specific influence is imperative to develop therapeutic strategies for cardiomyopathy induced by a maternal Western diet. We developed a prenatal maternal Western diet exposure model in C57/B6 mice to investigate cardiac morphology and function through histological analysis and echocardiography. RNA sequencing and analysis were utilized to elucidate the mechanisms underlying the impact of a maternal Western diet and N-acetylcysteine treatment on cardiomyopathy. Additionally, ELISAs, transmission electron microscopy, and flow cytometry were employed to assess the antioxidant defense system and mitochondrial ROS levels in progenitor cardiomyocytes. N-acetylcysteine significantly mitigated cardiomyocyte hypertrophy, myocardial interstitial fibrosis, collagen type I accumulation, and left ventricular remodeling induced by a maternal Western diet, particularly in male offspring. Furthermore, N-acetylcysteine reversed the increase in apoptosis and the increase in the β/α-MyHC ratio in the myocardium of offspring that results from a maternal Western diet. RNA sequencing and GSEA revealed that the beneficial effects of N-acetylcysteine were linked to its ability to modulate oxidative phosphorylation pathways. Additionally, N-acetylcysteine treatment during pregnancy can markedly elevate glutathione levels, augment glutathione peroxidase (GPx) activity, and mitigate the accumulation of mitochondrial ROS caused by a maternal Western diet. N-acetylcysteine mitigated cardiomyopathy induced by a maternal Western diet by bolstering glutathione synthesis and enhancing GPx activity, thereby scavenging mitochondrial ROS and modulating oxidative phosphorylation pathways.

Arrhythmogenic Mitral Valve Prolapse Revisited: A Not Uncommon Cause of Youthful Sudden Death in Athletes and Women

BackgroundSudden deaths (SDs) in young people, including competitive athletes, albeit uncommon, are usually attributable to genetic, congenital or acquired cardiovascular conditions. However, it is under-appreciated that mitral valve prolapse (MVP), a relatively common valvular heart disease, is associated with SD in this youthful population. MethodsForty-three MVP-related SDs were identified from 2 large cardiovascular registries with pathologic, clinical, and demographic findings reported. ResultsEvents occurred in both sexes, but females were unexpectedly common (49%); median age was 22 ± 8 years, and 29 (67%) were engaged in competitive sports, including 17 with preparticipation examination. Of the 43 MVP cases, 21 died suddenly during or just after vigorous exercise, including 6 during organized sports. Sixteen (37%) had been evaluated by a cardiologist, resulting in confirmed MVP diagnosis in 11. Pathologic findings characteristic of MVP included bileaflet myxomatous involvement (in all cases) and areas of interstitial or replacement myocardial fibrosis (in 79%), most evident in posterolateral left ventricular wall. ConclusionsArrhythmogenic myxomatous degeneration (MVP) is an under-recognized cause of SD in young people, including competitive athletes, disproportionally affecting females and requires a high index of clinical suspicion. Frequency of left ventricular fibrosis in these young people with MVP suggests a mechanism for ventricular tachyarrhythmias and SD, relevant to future risk stratification.

Elevated myocardial extracellular volume fraction is associated with the development of conduction pathway defects following transcatheter aortic valve replacement.

Transcatheter aortic valve replacement (TAVR) has become an established method of aortic stenosis treatment but suffers from the risk of heart block and pacemaker requirement. Risk stratification for patients who may develop heart block remains imperfect. Simultaneously, myocardial fibrosis as measured by cardiac magnetic resonance imaging (CMR) has been demonstrated as a prognostic indicator of ventricular recovery and mortality following TAVR. However, the association of CMR-based measures of myocardial fibrosis with post-TAVR conduction disturbances has not yet been explored. We evaluated whether myocardial fibrosis, as measured by late gadolinium enhancement and extracellular volume (ECV) from CMR would be associated with new conduction abnormalities following TAVR. One hundred seventy patients who underwent CMR within 2 months before TAVR were retrospectively reviewed. Septal late gadolinium enhancement (LGE) and ECV measurements were made as surrogates for replacement and interstitial fibrosis respectively. New conduction abnormalities were defined by the presence of transient or permanent atrioventricular block, new bundle branch blocks, and need for permanent pacemaker. Association of myocardial fibrosis and new conduction derangements were tested using receiver operator curve (ROC) and regression analysis in patients with and without pre-existing conduction issues. Forty-six (27.1%) patients developed post-TAVR conduction deficits. ECV was significantly higher among patients who experienced new conduction defects (26.2 ± 3.45% vs. 24.7% ± 4.15%, p value: 0.020). A greater fraction of patients that had new conduction defects had an elevated ECV of ≥26% (54.3% vs. 36.3%, p value: 0.026). ECV ≥ 26% was independently associated with the development of new conduction defects (odds ratio [OR]: 2.364, p value: 0.030). ROC analysis revealed a significant association of ECV with new conduction defects with an area under the receiver operating characteristic curve (AUC) of 0.632 (95% confidence interval: 0.555-0.705, p value: 0.005). The combination of prior right bundle branch block (RBBB) and ECV revealed a greater AUC of 0.779 (0.709-0.839, p value: <0.001) than RBBB alone (Delong p value: 0.049). No association of LGE/ECV with new conduction defects was observed among patients with pre-existing conduction disease. Among patients without baseline conduction disease, ECV was independently associated with the development of new conduction deficits (OR: 3.685, p value: 0.008). The present study explored the association of myocardial fibrosis, as measured by LGE and ECV with conduction deficits post-TAVR. Our results demonstrate an association of ECV, and thereby interstitial myocardial fibrosis, with new conduction derangement post-TAVR and introduce ECV as a potentially new risk stratification tool to identify patients at higher risk for needing post-TAVR surveillance and/or permanent pacemaker.

#1515 Myocardial remodeling is associated with redistribution of phosphate, PIT1/ERK1/2 up-regulation and signaling pathways alterations in mild CKD model

Abstract Background and Aims Patients with CKD have significantly increased cardiovascular risk, and heart failure is a leading cause of morbidity and mortality in these patients. Myocardial hypertrophy is a hallmark of cardiac remodeling and dysfunction in CKD and is known to be mediated by angiotensin II, catecholamines, hyperphosphatemia, hyperparathyroidism, increase in FGF23, decrease in Klotho and alterations in various signaling pathways including calcineurin, mitogen-activated protein kinase ERK1/2, calmodulin-dependent protein kinase II etc. Less well understood are the mechanisms of fibrosis and intramyocardial arterial remodeling in CKD, which may be related to hyperphosphatemia and decreased renal and systemic Klotho. The aim of this study was to evaluate the molecular and cellular features of myocardial remodeling in experimental mild CKD. Method We induced CKD by 3/4 nephrectomy (Nx) in adult male spontaneously hypertensive rats (SHR) with a follow-up period of 4 months. Animals were fed standard chow containing 0.6% phosphate. Sham-operated Wistar rats and SHR served as controls. We measured serum creatinine, renal interstitial fibrosis area, systolic blood pressure (BP), myocardial mass index (MMI), histological indices of myocardial hypertrophy, interstitial fibrosis and intramyocardial artery (IA) remodeling (H&amp;E, Masson's trichrome, von Kossa stain), myocardial phosphorus content, serum levels of inorganic phosphate (Pi), PTH and FGF23. Myocardial expression of phosphate transporters PiT1, ERK1/2, WNT, BMP, Notch, Hedgehog signaling pathways and LRG4 molecules was evaluated by PCR-RT, IHC and IF (Zeiss LSM 710; study performed at the Centre for Collective Use “Confocal Microscopy” of the Pavlov Institute of Physiology, Russian Academy of Sciences). Results Chronic kidney injury and phosphate regulatory factors did not differ, whereas BP and MMI were higher in sham SHR vs. Wistar rats (Fig. 1). Nx rats showed features of mild chronic kidney injury before the elevation of serum PTH, FGF23 levels (Fig. 1). Myocardial P content and serum Pi were higher in Nx and in the combined SHR group and directly correlated with indices of IA remodeling. Cardiomyocyte diameter, myocardial interstitial and perivascular fibrosis were higher in Nx (Figs 1, 2a) and accompanied with upregulation in Ppp3ca mRNA (calcineurin A, Fig. 2b), Mapk1 mRNA (ERK2, Fig. 2b), phospho-ERK1/2 (Figs 1, 3), PiT1 (Figs 1, 2c), Lgr4 (Fig. 2c) and downregulation of Hes1 mRNA (Fig. 2b). PiT1 and pospho-ERK1/2 were co-expressed in IA media from SHR (Fig. 2c). In Nx, nestin and LGR4 were expressed by IA adventitia and media cells, myocardial interstitial cells, and occasionally co-localized (Fig. 2c). Hes1 expression was detected in IA and capillary endothelial cells and co-localised with Gli1 in IA media; Gli1 was also detected in cardiomyocyte nuclei (Fig. 2c). In SHR, beta-catenin expression in cardiomyocytes was more pronounced in Nx (Fig. 2c). Conclusion Mild CKD is associated with histological and molecular features of cardiomyocyte hypertrophy, myocardial fibrosis and intramyocardial arterial remodeling, which are probably modulated by phosphate redistribution and its tissue retention involving upregulation of PiT1 and ERK1/2, as well as alterations in signals related to progenitor regulation and myocyte hypertrophy.

Possible Role of Gut Microbiota Alterations in Myocardial Fibrosis and Burden of Heart Failure in Hypertensive Heart Disease.

Epidemiological studies have revealed that hypertensive heart disease is a major risk factor for heart failure, and its heart failure burden is growing rapidly. The need to act in the face of this threat requires first an understanding of the multifactorial origin of hypertensive heart disease and second an exploration of new mechanistic pathways involved in myocardial alterations critically involved in cardiac dysfunction and failure (eg, myocardial interstitial fibrosis). Increasing evidence shows that alterations of gut microbiota composition and function (ie, dysbiosis) leading to changes in microbiota-derived metabolites and impairment of the gut barrier and immune functions may be involved in blood pressure elevation and hypertensive organ damage. In this review, we highlight recent advances in the potential contribution of gut microbiota alterations to myocardial interstitial fibrosis in hypertensive heart disease through blood pressure-dependent and blood pressure-independent mechanisms. Achievements in this field should open a new path for more comprehensive treatment of myocardial interstitial fibrosis in hypertensive heart disease and, thus, for the prevention of heart failure.

“Interstitial fibrosis is associated with left atrial remodeling and adverse clinical outcomes in selected low-risk patients with hypertrophic cardiomyopathy”

BackgroundCardiovascular magnetic resonance (CMR) extracellular volume (ECV) allows non-invasive detection of myocardial interstitial fibrosis, which may be related to diastolic dysfunction and left atrial (LA) remodeling in hypertrophic cardiomyopathy (HCM). While the prognostic role of LGE is well-established, interstitial fibrosis and LA dysfunction are emerging novel markers in HCM. This study aimed to explore the interaction between interstitial fibrosis by ECV, LA morpho-functional parameters and adverse clinical outcomes in selected low-risk patients with HCM. Methods115 HCM patients and 61 matched controls underwent CMR to identify: i) interstitial fibrosis by ECV in hypertrophied left ventricular LGE-negative remote myocardium (r-ECV); ii) LA indexed maximum (LAVi max) and minimum (LAVi min) volumes, ejection fraction (LA-EF) and strain (reservoir εs, conduit εe and booster εa), by CMR feature-tracking. 2D-echocardiographic assessment of diastolic function was also performed within 6 months from CMR. A composite endpoint including worsening NYHA class, heart failure hospitalization, atrial fibrillation and all-cause death was evaluated at 2.3 years follow-up. HCM patients were divided into two groups, according to r-ECV values of controls. ResultsPatients with r-ECV ≥29% (n = 45) showed larger LA volumes (LAVimax 63 vs. 54 ml/m2, p < 0.001; LAVimin 43 vs. 28 ml/m2, p 〈0001), worse LA function (εs 16 vs. 28%, εe 8 vs. 15%, εa 8 vs. 14%, LA-EF 33 vs. 49%, all p < 0.001) and elevated Nt-proBNP (1115 vs. 382 pg/ml, p = 0.002). LA functional parameters inversely correlated with r-ECV (εs r = −0.54; LA-EF r = −0.46; all p < 0.001) and E/e' (εs r = −0.52, LA-EF r = −0.46; all p < 0.006). r-ECV ≥29% and LAVi min >30 ml/m2 have been identified as possible independent factors associated with the endpoint. ConclusionsIn HCM diffuse interstitial fibrosis detected by increased r-ECV is associated with LA remodeling and emerged as a potential independent predictor of adverse clinical outcomes, on top of the well-known prognostic impact of LGE.

ASSOCIATIONS BETWEEN GENETICALLY PREDICTED PULSE PRESSURE AND TARGET ORGAN DAMAGE: A MENDELIAN RANDOMIZATION STUDY

Objective: Large-artery stiffness (LAS) leads to an increased pulse pressure (PP) and is thought to induce target organ damage (TOD). However, causal associations of PP have not been unequivocally assessed in humans. We aimed to investigate the bi-directional associations between genetically predicted increased PP and phenotypes of TOD using Mendelian randomization (MR). Design and method: Bi-directional MR analyses were performed to investigate associations between genetically predicted PP and: left ventricular mass (LVM), myocardial interstitial fibrosis, heart failure (HF), chronic kidney disease (CKD), cognitive performance, brain white matter hyperintensities (WMH), type 2 diabetes (T2D) and preeclampsia (PrE). Multivariable MR was conducted to investigate the effect of PP on significant outcomes, independently of mean arterial pressure (MAP). Results: For a 10-mmHg increase in genetically-predicted PP, the odds ratios (ORs) were 1.113 (95%CI=1.085-1.137, P&lt;0.001) for HF, 1.075 (95%CI=1.048-1.103, P&lt;0.001) for CKD, 1.137 (95%CI=1.102-1.173, P&lt;0.001) for T2D, and 1.435 (95%CI=1.256-1.638, P&lt;0.001) for PrE. Similarly, a 10-mmHg increase in genetically-predicted PP was associated with a greater LVM (beta estimate=3.527 g/m2, 95%CI=3.026-4.028, P&lt;0.001). The association of genetically predicted PP on risk of HF, CKD and T2D was independent of genetically-predicted MAP. Bidirectional MR also supported a causal effect of genetically predicted log-odds of T2D on PP (beta estimate=0.527 mmHg, 0.396-0.658, P&lt;0.001), and PrE on PP (beta estimate=2.365 mmHg, 0.783-3.947, P=0.003) indicating a potential bidirectional relationship. Conclusions: We provide evidence supporting causal associations between PP and T2D, CKD, HF and increased risk of LV hypertrophy in humans, consistent with the deleterious effects of LAS on LV afterload and on microvascular integrity in low-resistance target organs. Early interventions aimed at lowering LAS may lead to lowering the risk of adverse outcomes.