Cardiomegaly Research Articles

Effect and mechanism of Adipokine Omentin-1 on cardiac hypertrophy in heart failure with preserved ejection fraction

Abstract Background Omentin-1 secreted by epicardial adipose tissue can inhibit ventricular remodeling and improve early cardiac function after myocardial infarction. Our previous studies have identified the omentin-1 receptor as integrin receptors αvβ3 and αvβ5. However, the effect of omentin-1 on heart failure with preserved ejection fraction (HFpEF) remains poorly understood. Purpose The present study aims to study the role and mechanism of omentin-1 in cardiac function and myocardial cell structure in HFpEF. Methods and Results The influences of omentin-1 were investigated in HFpEF mice (HFD (60% calories from lard) and L-NAME (0.5 g/L in drinking water)), which were treated in vivo. Echocardiography showed better diastolic function in HFpEF mice treated with omentin-1 (5 ug/kg/h) subcutaneously for 4 weeks, and tissue staining showed alleviated myocardial fibrosis and myocardial hypertrophy. The RNA sequencing analysis revealed variations in the gene expression related to ketone body metabolism in HFpEF mice after omentin-1 treatment (600 ng/ml). The supernatant was obtained from mouse bone marrow macrophages treated with ultrapure endotoxin and ATP and was utilized as the macrophage-conditioned medium for culturing primary cardiomyocytes, which were stimulated with isoproterenol for 48 hours to construct the HFpEF cardiomyocyte model. In the heart tissue of HFpEF mice and HFpEF cardiomyocytes treated with omentin-1, there was a notable increase in the expression of a pivotal enzyme of ketone body metabolism- succinyl-CoA transferase (SCOT), and a decrease in the expression of hypertrophy signal. The myocardial hypertrophy model was established by stimulating the myocardial cell line H9C2 with isoproterenol. Following the inhibition of the integrin receptor and PI3K-AKT pathway, the impacts of omentin-1 on SCOT and myocardial hypertrophy signal expression in hypertrophic cardiomyocytes were eliminated. Conclusion This study provides evidence for the effects of omentin-1 on cardiac function and myocardial structure in HFpEF and proposes that omentin-1 may stimulate the downstream PI3K/AKT pathway via integrin receptors on cardiomyocytes, leading to increased expression of SCOT and improvement of cardiomyocyte hypertrophy.

First time evaluation of myocardium microRNA profile in Anderson-Fabry disease: implications in the pathological processes

Abstract Background Anderson Fabry disease (AFD) is an X-linked lysosomal disorder, characterized by progressive sphingolipid storage and organ dysfunction. Cardiac involvement is characterized by left ventricular hypertrophy, inflammation and fibrosis and is leading cause of mortality. MicroRNAs (miRNAs) are emerging as promising biomarkers in medicine, as they are dysregulated in many human diseases, offering opportunities to improve our understanding of disorders and discover new therapeutic targets. However, so far, only a few studies have evaluated the role of miRNAs in Fabry disease, and cardiac tissue miRNAs have never been assessed. Purpose To determine the specific tissue miRNA profile analyzing myocardial tissue of AFD patients and to evaluate their relationship with the severity of cardiac involvement. Methods 19 AFD patients (10 females [53%]; median age 53 years [IQR 43-63]) undergoing right ventricular endomyocardial biopsy (n=15) or surgical septal myectomy (n=4), standard cardiac magnetic resonance (1.5T, cines for maximum wall thickness (MWT) and indexed LV mass (LVMi) calculation) and high-sensitivity Troponin I (TnI) dosage were included and compared to 7 endomyocardial biopsies of controls. Myocardial samples were fixed in formalin and embedded in paraffin. RNA was extracted from 3-5 slides of tissue and used to generate small RNA libraries (Qiagen) for Next Generation Sequencing analysis on Illumina sequencer. Raw data were normalized and analyzed using DEseq2 pipeline. Correlations were performed using Pearson r; a p < 0.05 was considered statistically significant. Results In AFD group median MWT was 13 mm [IQR 8-17], LVMi was 72 g/m2 [IQR 46-97]. TnI was increased in 9 patients (47%) and NT-proBNP in 8 (42%). 6 patients were on specific AFD treatment. We identified 9 miRNAs differentially expressed in AFD patients compared to controls; miRPath analysis revealed that these miRNAs are associated to pathways involved in AFD pathogenesis (autophagy and mTOR signalling, HIF-1, apoptosis, TGF-beta signalling and inflammation) (figure 1). Moreover, we found 10 miRNAs that were differentially expressed in maximal wall thickness (<10 mm, 10-15 mm, >15 mm) groups (figure 2), in particular 3 miRNAs that progressively increased at the increasing of thickness. Among these miRNAs, miR-21-5p showed the strongest correlation with myocardial hypertrophy (r=0.869, p value<0.001 for MWT; r=0.905, p<0.001 for LVMi) and with cardiac damage (r=0.831, p<0.001 for TnI). Additionally, miR-21-5p had a modest correlation with age (r=0.518, p=0.05) and did not differ between patients on specific AFD treatment and patients not treated (p=0.660). Conclusions This study for the first time evaluated the myocardial miRNA profile in AFD patients and identified miR-21-5p as a cardiac biomarker correlating with clinical heart involvement, both in terms of left ventricular hypertrophy (MWT, LVMi) and myocardium damage (troponin).Figure 1Figure 2

Changes in peak oxygen consumption on excercise and cardiomyopathy disease stage in Fabry disease

Abstract Background Fabry disease (FD) is an X-linked lysosomal storage disorder manifesting as deficiency in the enzyme α-Galactosidase A (1) resulting in multi-organ accumulation of globotriaosylceramide (Gb3) (2) This causes predominantly cardiac, renal and cerebrovascular manifestations. Shortness of breath and exercise intolerance are common and can be related to multiple underlying mechanisms. Cardiopulmonary exercise testing (CPEX) quantifies aerobic fitness, functional capacity, chronotropic and haemodynamic response to exercise, and attributes effort intolerance to different aetiologies, including impaired cardiac and respiratory function. Purpose We hypothesise that there is progressive effort intolerance that reflects continual cardiac Gb3 accumulation, becoming common during myocardial hypertrophy and disabling in the fibrosis and inflammation stage. The aims of this study were to ascertain frequency and severity of exercise intolerance in FD by investigating the relationship between peak maximal oxygen uptake (VO2 max) and cardiac disease stage, quantified based on a four-point scale, as proposed in published literature (3). Methods This was a retrospective review of adults with FD and exercise intolerance attending a specialist clinic who had undergone either CPEX or six-minute walk testing (6MWT) in those less mobile. Biochemical, cardiac magnetic resonance (CMR) imaging and transthoracic echocardiographic (TTE) data were also collected. Results N=54 patients underwent CPEX and N=35 patient underwent 6MWT. Estimated peak VO2 max was calculated using 6MWD in those undergoing 6MWT. Median age was 54 (IQR 40-62) years and 53% were male. Patients were equally distributed across disease stage (1-4). There were significant trends in age (increasing) and gender (male predominance) from stage 1-4. Age/sex-normalised peak VO2 max values were calculated as per published literature due to the confounding effect of age and male gender. Mean normalised VO2 max was 35.5ml/kg/min for the cohort, an underperformance of 12.3 ± 8.0 ml/kg/min. The magnitude of underperformance began from stage 1 (no cardiomyopathy) and increased with each stage (Figure 1). Impairments in renal (creatinine and albumin: creatinine ratio) and cardiac biomarkers (troponin and N-terminal pro brain natriuretic peptide) was associated with reduced VO2 max (Table 1). Increased indexed left ventricular mass on CMR and impairments in atrial volume and function on TTE were also associated with a reduction in VO2 max (Table 1). Conclusion This study is the first of its kind to demonstrate impairments in peak aerobic capacity in adults with FD and no cardiomyopathy (stage 1) which impairs further with cardiac disease stage. Future work should focus on how disease-modifying therapy can target this using VO2 as an endpoint and marker of response.Normalised peak VO2 max + disease stageVO2 max and blood / imaging parameters

Cardiac secreted-HSP90alpha in cardiomyocyte hypertrophy by N-Cadherin mediated signaling under pressure overload

Abstract Background Left ventricular hypertrophy (LVH) in response to pressure overload is strongly associated with adverse cardiovascular outcomes. Heat shock protein 90 (HSP90) has been reported to be involved in cardiac remodeling under stress. Aims Here, we evaluate whether serum HSP90α (an isoform of HSP90) increases and associates with cardiac hypertrophy in patients with hypertension or severe aortic stenosis (AS), and explore the potential mechanisms in experimental pressure overload mouse model. Methods Serum HSP90α levels in patients with hypertension or aortic stenosis (AS) were determined by ELISA. Pressure overload mouse model was built by a transverse aortic constriction (TAC). Cardiac function was assessed by echocardiography. Cardiac hypertrophy was examined by histology, western blot and RNA analysis. Results Serum levels of HSP90α were higher in patients with hypertension or AS than in the control group, respectively, and the levels positively correlated with LVH. HSP90α levels also increased in heart tissues of patients with obstructive hypertrophic cardiomyopathy (HCM), and mice after TAC, in parallel with the hypertrophic markers. TAC induced the enhanced expression and secretion of HSP90α from cardiomyocytes and cardiac fibroblasts. Knockdown of HSP90α or blockade of extracellular HSP90α (eHSP90α) prevent the development of LVH under pressure overload in vivo and in vitro. By Nano-HPLC-MS/MS analysis, we identified eHSP90α interacted with N-cadherin in cardiomyocyte surface, which induced the activation of β-catenin and promoted β-catenin to bind TCF7 (a member of TCF/Lef family) in nucleus, enhanced the transcription of hypertrophic genes, contributing to cardiac hypertrophy and dysfunction under pressure overload. Conclusions Our data demonstrated that cardiac secreted-HSP90α promoted myocardial hypertrophy by N-Cadherin mediated β-catenin/TCF7 signaling under pressure overload. It indicates the therapeutic potential of targeting HSP90α-initiated signaling against cardiac hypertrophy and dysfunction under pressure overload.

Increased Susceptibility of Cardiac Tissue to PM2.5-Induced Toxicity in Uremic Cardiomyopathic Rats Is Linked to Elevated Levels of Mitochondrial Dysfunction.

Patients with chronic kidney disease (CKD) frequently develop uremic cardiomyopathy, characterized by mitochondrial dysfunction as one of its pathologically significant mediators. Given that PM2.5 specifically targets cardiac mitochondria, exacerbating toxicity, this study addresses the potential alterations in the severity of PM2.5 toxicity in the context of CKD conditions. Female Wistar rats were exposed to PM2.5 at a concentration of 250 μg/m3 daily for 3 h for 21 days after which an adenine-induced CKD model was developed. While both PM2.5 exposure and the induction of CKD in rats lead to cardiomyopathy, the CKD animals exposed to PM2.5 exhibited a notably severe extent of myocardial hypertrophy and fibrosis. ECG recordings in CKD+ PM2.5 animals revealed a depressed ST segment and prolonged QRS interval, with both PM2.5 and CKD animals displaying an elevated ST segment. Subcellular level analysis confirmed a significantly low mitochondrial copy number and a severe decline in mitochondrial bioenergetic function in the CKD+ PM2.5 group. The prominent decline in PGC1-α further affirmed the severe mitochondrial functional deterioration in CKD+ PM2.5 animals compared to other experimental groups. Additionally, myocardial calcification was enhanced in CKD+ PM2.5 animals, heightening the susceptibility of CKD animals to PM2.5 toxicity. In summary, our findings suggest that the increased vulnerability of CKD myocardium to PM2.5-induced toxicity may be attributed to severe mitochondrial damage and increased calcification in the myocardium.

ALDH2 mediates the effects of sodium-glucose cotransporter 2 inhibitors (SGLT2i) on improving cardiac remodeling

BackgroundSodium-glucose cotransporter-2 inhibitors (SGLT2i) are now recommended for patients with heart failure, but the mechanisms that underlie the protective role of SGLT2i in cardiac remodeling remain unclear. Aldehyde dehydrogenase 2 (ALDH2) effectively prevents cardiac remodeling. Here, the key role of ALDH2 in the efficacy of SGLT2i on cardiac remodeling was studied.MethodsAnalysis of multiple transcriptomic datasets and two-sample Mendelian randomization were performed to find out the differentially expressed genes between pathological cardiac hypertrophy models (patients) and controls. A pathological cardiac hypertrophy mouse model was established via transverse aortic constriction (TAC) or isoproterenol (ISO). Cardiomyocyte-specific ALDH2 knockout mice (ALDH2CMKO) and littermate control mice (ALDH2flox/flox) were generated to determine the critical role of ALDH2 in the preventive effects of dapagliflozin (DAPA) on cardiac remodeling. RNA sequencing, gene knockdown or overexpression, bisulfite sequencing PCR, and luciferase reporter assays were performed to explore the underlying molecular mechanisms involved.ResultsOnly ALDH2 was differentially expressed when the differentially expressed genes obtained via Mendelian analysis and the differentially expressed genes obtained from the multiple transcriptome datasets were combined. Mendelian analysis revealed that ALDH2 was negatively related to the severity of myocardial hypertrophy in patients. DAPA alleviated cardiac remodeling in mouse hearts subjected to TAC or ISO. ALDH2 expression was reduced, whereas ALDH2 expression was restored by DAPA in hypertrophic hearts. Cardiomyocyte specific ALDH2 knockout abolished the protective role of DAPA in preventing cardiac remodeling. ALDH2 expression and activity were increased in DAPA-treated neonatal rat primary cardiomyocytes (NRCMs), H9C2 cells and AC16 cells. Moreover, DAPA upregulated ALDH2 in peripheral blood mononuclear cells (PBMCs) from patients with type 2 diabetes. Sodium/proton exchanger 1 (NHE1) inhibition contributed to the regulation of ALDH2 by DAPA. DAPA suppressed the production of reactive oxygen species (ROS), downregulated DNA methyltransferase 1 (DNMT1) and subsequently reduced the ALDH2 promoter methylation level. Further studies revealed that DAPA enhanced the binding of nuclear transcription factor Y, subunit A (NFYA) to the promoter region of ALDH2, which was due to the decreased promoter methylation level of ALDH2.ConclusionsThe upregulation of ALDH2 plays a critical role in the protection of DAPA against cardiac remodeling. DAPA enhances the binding of NFYA to the ALDH2 promoter by reducing the ALDH2 promoter methylation level through NHE1/ROS/DNMT1 pathway.Graphical abstract

Apelin/APJ signaling in IGF-1-induced acute mitochondrial and antioxidant effects in spontaneously hypertensive rat myocardium.

IGF-1 and apelin are released in response to exercise training with beneficial effects. Previously we demonstrated that a swimming routine is effective to convert pathological into physiological cardiac hypertrophy, and that IGF-1 improves contractility and the redox state, in spontaneously hypertensive rats (SHR). Now, we hypothesize that the apelinergic pathway is involved in the cardioprotective effects of IGF-1 in the SHR. We assessed the redox state and mitochondrial effects of IGF-1 or apelin in the presence/absence of AG1024 or ML221 [pharmacological antagonists of IGF1 (IGF1R) and apelin (APJ) receptors, respectively] in SHR isolated cardiomyocytes or perfused hearts. Acute IGF-1 (10 nmol/L) significantly: -reduced H2O2 production (IGF-1:62 ± 6; control:100 ± 8.1, %), -increased the activity of superoxide dismutase (IGF-1:193 ± 17, control: 100 ± 13,%), -prevented H2O2-induced ΔΨm loss (TMREF10min/F0 min: IGF-1:0.93 ± 0.017, control: 0.72 ± 0.029), -reduced mitochondrial permeability transition pore (mPTP) opening estimated by the calcium retention capacity (nmol/mg protein, IGF-1:251 ± 34, control:112 ± 5), and -increased P-AMPK (IGF-1:129 ± 0.9, control: 100 ± 2%) and P-AKT (IGF-1:143 ± 17 control:100 ± 6, %). These effects were suppressed not only by the antagonism of IGF1R but also of APJ. Moreover, IGF-1 significantly increased APJ (IGF-1:198 ± 29 control:100 ± 15,%) and apelin mRNAs (IGF-1:251 ± 48, control:100 ± 6,%). On the other hand, an equipotent dose of exogenous apelin (50 nmol/L) emulated IGF-1 effects being cancelled by the antagonism of APJ however not by AG1024. IGF-1/IGF1R stimulates the apelinergic pathway, improving the redox balance and mitochondria status in the pathologically hypertrophied myocardium of the SHR.

Role of autophagy in myocardial remodeling after myocardial infarction.

Autophagy is the process of reusing the body's senescent and damaged cell components, which can be regarded as the cellular circulatory system. There are three distinct forms of autophagy: macro-autophagy, micro-autophagy, and chaperone-mediated autophagy. In the heart, autophagy is regulated mainly through mitophagy due to the metabolic changes of cardiomyocytes caused by ischemia and hypoxia. Myocardial remodeling is characterized by gradual heart enlargement, cardiac dysfunction, and extraordinary molecular changes. Cardiac remodeling after myocardial infarction is almost inevitable, which is the leading cause of heart failure. Autophagy has a protective effect on myocardial remodeling improvement. Autophagy can minimize cardiac remodeling by preventing misfolded protein accumulation and oxidative stress. This review summarizes the nestest molecular mechanisms of autophagy and myocardial remodeling, the protective effects, and the new target of autophagy medicine in cardiac remodeling. The future development and challenges of autophagy in heart disease are also summarized.

Serial and regional assessment of the right ventricular molecular and functional response to pressure-loading.

Right ventricular(RV) function determines outcomes in RV pressure-loading. A better understanding of the time-course and regional distribution of RV remodeling may help optimize targets and timing for therapeutic intervention. We sought to characterize RV remodeling between zero and 6-weeks after initiation of RV pressure-loading. Thirty-six rats were randomized to either sham surgery or to pulmonary artery banding(PAB). After echocardiography and conductance catheter studies, groups of rats were euthanized at 1-week, 3-weeks and 6-weeks after sham surgery, or induction of RV pressure-loading, for RV histological, RNA and molecular analysis. A vigorous inflammatory response characterized by increased RV inflammatory cytokines, chemokines and macrophage markers was observed at 1-week following PAB. Metabolic changes, TGF-β1 canonical signaling, collagenous fibrosis deposition and apoptosis were already significantly increased by 1-week after PAB. Genes marking fibroblast activation were upregulated at 1-week but not 6-week post-PAB surgery. Mitochondrial dysfunction as evidenced by increased PDK activity and decreased PDH phosphorylation significantly at 6-week post PAB. These processes preceded the development of overt myocardial hypertrophy and impaired echo parameters of systolic and diastolic function which occurred significantly from 3-weeks after PAB. RV myocardial inflammation, metabolic shift, metabolic gene transcription and pro-fibrotic signaling occur early after initiation of pressure-loading when RV pressures are only moderately elevated, before the development of overt myocardial hypertrophy and dysfunction, suggesting that adaptive hypertrophy and maladaptive remodeling occur simultaneously. These results suggest that therapeutic intervention to reduce adverse RV remodeling may be needed earlier and at lower thresholds than currently employed.

Protective Role of (-)-Epicatechin on Trimethylamine-N-Oxide (TMAO)-Induced Cardiac Hypertrophy via SP1/SIRT1/SUMO1 Signaling Pathway.

(-)-Epicatechin (EPI) is beneficial for cardiovascular health. Trimethylamine N-oxide (TMAO), a gut microbe-derived food metabolite, is strongly associated with the risk of cardiovascular diseases. However, the effects and underlying mechanisms of EPI on TMAO-induced cardiac hypertrophy remain unclear. This study aimed to determine whether EPI inhibits TMAO-induced cardiac hypertrophy. Plasma levels of TMAO in control participantsand patients with cardiac hypertrophy were measured and analyzed. Male C57BL/6 mice were randomly divided into control group, TMAO group, EPI group and TMAO + EPI group. According to the groups assignments, mice received intraperitoneal (i.p.) injection of normal saline or i.p. injection of TMAO (150mg/kg/day) for 14days. The EPI group was given intragastric (i.g.) administration of EPI alone (1mg/kg/day) for 21days, and TMAO + EPI group received i.g. administration of EPI for 7days before starting i.p. injection of TMAO, continuing until the end of the TMAO treatment. Histological analyses of the mice's hearts was accessed by H&E and Masson staining. In vitro, H9c2 cells were induced to hypertrophy by TMAO (10µM) for 24h and were pre-treated with or without EPI (10µM) for 1h. Protein level of cardiac hypertrophy markers and Sp1/SIRT1/SUMO1 pathway were determined by western blot. The plasma level of TMAO was 2.66 ± 1.59μmol/L in patients with cardiac hypertrophy and 0.62 ± 0.30μmol/L in control participants. EPI attenuated TMAO-induced hypertrophy in H9c2 cells. In vivo, TMAO induced cardiac hypertrophy and impaired the cardiac function of mice. Pathological staining showed that TMAO induced cardiac hypertrophy and collagen deposition in mice. EPI treatment improved the cardiac function, inhibited the myocardial hypertrophy induced by TMAO. EPI significantly attenuated the TMAO-induced upregulation of ANP and BNP and the downregulation of SP1, SIRT1 and SUMO1 in vivo and in vitro. EPI may suppress TMAO-induced cardiac hypertrophy by activating the Sp1/SIRT1/SUMO1 signaling pathway.

Mechanisms of pathogenicity in the hypertrophic cardiomyopathy-associated TNNI3 c.235C > T variant.

Hypertrophic cardiomyopathy (HCM) is typically manifested as a hereditary disorder, with 30 %-60 % of cases linked to cardiac sarcomere gene mutations. Despite numerous identified TNNI3 mutations associated with HCM, their severity, prevalence, and disease progression vary. The link between TNNI3 variants and phenotypes remains largely unexplored. This study aims to elucidate the impact of the TNNI3 c.235C > T mutation on HCM through clinical research and cell experiments and to explore its mechanism in HCM development. We screened an HCM family for pathogenic gene mutations using gene sequencing. The proband and family members were assessed through electrocardiography, echocardiography, and cardiac MRI, and a pedigree map was created for disease prediction analysis. Mutant plasmids were constructed with the TNNI3 c.235C > T mutation and transfected into the AC16 human cardiomyocyte cell line to investigate the mutation's effects. The TNNI3 c.235C > T mutation was identified as the disease-causing variant in the family. This mutation led to the upregulation of hypertrophy-associated genes ANP, BNP, and MYH7, increased cardiomyocyte size, and activation of the ERK signaling pathway. Further investigations revealed that the TNNI3 c.235C > T mutation impaired mitochondrial function, disrupted cardiomyocyte metabolism, and increased cellular autophagy and apoptosis. The TNNI3 c.235C > T gene mutation may be a pathogenic factor for HCM, showing heterogeneous features and clinical phenotypes. This mutation induces myocardial hypertrophy, activates the ERK signaling pathway, and exacerbates mitochondrial dysfunction, apoptosis, and autophagy in cardiomyocytes. These findings provide insights into the mechanism of HCM caused by gene mutations and may inform HCM treatment strategies.

PFKP inhibition protects against pathological cardiac hypertrophy by regulating protein synthesis

Metabolic reprogramming precedes most alterations during pathological cardiac hypertrophy and heart failure (HF). Recent studies have revealed that Phosphofructokinase, platelet (PFKP) has a wealth of metabolic and non-metabolic functions. In this study, we explored the role of PFKP in cardiac hypertrophic growth and HF. The expression level of PFKP was elevated both in pathological cardiac remodeling mouse model challenged by transverse aortic constriction (TAC) surgery and in the neonatal rat cardiomyocytes (NRCMs) stimulated by phenylephrine (PE). In global PFKP knockout (PFKP-KO) mice, cardiac hypertrophy was ameliorated under TAC surgery, while overexpression of PFKP by intravenous injection of adeno-associated virus 9 (AAV9) under the cardiac troponin T (cTnT) promoter worsened myocardial hypertrophy and fibrosis. In NRCMs, small interfering RNA (SiRNA) knockdown or adenovirus (Adv) overexpression of PFKP was employed and the intervention of PFKP showed a similar phenotype. Mechanistically, immunoprecipitation combined with liquid chromatography-tandem mass spectrometry (IP-MS/MS) analysis was used to identify the interacting proteins of PFKP. Eukaryotic translation initiation factor 2 subunit beta (EIF2S2) was identified as the downstream target of PFKP. In the PE-stimulated NRCM hypertrophy model and mouse TAC model, knocking down EIF2S2 after PFKP overexpression reduced the synthesis of new proteins and alleviated the hypertrophy phenotype. Our findings illuminate that PFKP participates in pathological cardiac hypertrophy partly by regulating protein synthesis through EIF2S2, which provides a new clue for the involvement of metabolic intermediates in signal transduction.

Microrna363-5p targets thrombospondin3 to regulate pathological cardiac remodeling.

Cardiac remodeling is an end-stage manifestation of multiple cardiovascular diseases, and microRNAs are involved in a variety of posttranscriptional regulatory processes. miR-363-5p targeting Thrombospondin3 (THBS3) has been shown to play an important regulatory role in vascular endothelial cells, but the roles of these two in cardiac remodeling are unknown. Firstly, we established an in vivo model of cardiac remodeling by transverse aortic narrow (TAC), and then we stimulated a human cardiomyocyte cell line (AC16) and a human cardiac fibroblast cell line (HCF) using 1μmol/L angiotensin II (Ang II) to establish an in vitro model of cardiac hypertrophy and an in vitro model of myocardial fibrosis, respectively. In all three of the above models, we found a significant decreasing trend of miR-363-5p, suggesting that it plays a key regulatory role in the occurrence and development of cardiac remodeling. Subsequently, overexpression of miR-363-5p significantly attenuated myocardial hypertrophy and myocardial fibrosis in vitro as evidenced by reduced the area of AC16, the cell viability of HCFs, the relative expression of the protein of fetal genes (ANP, BNP, β-MHC) and fibrosis marker (collagen I, collagen III, α-SMA), whereas inhibition of miR-363-5p expression showed the opposite trend. In addition, we also confirmed the targeted binding relationship between miR-363-5p and THBS3 by dual luciferase reporter gene assay, and the expression of THBS3 was directly inhibited by miR-363-5p. Moreover, overexpression of miR-363-5p with THBS3 simultaneously partially eliminated the delaying effect of miR-363-5p on myocardial hypertrophy and myocardial fibrosis in vitro. In conclusion, Overexpression of miR-363-5p attenuated the prohypertrophic and profibrotic effects of Ang II on AC16 and HCF by a mechanism related to the inhibition of THBS3 expression.

CEAM is a mitochondrial-localized, amyloid-like motif-containing microprotein expressed in human cardiomyocytes

Microproteins synthesized through non-canonical translation pathways are frequently found within mitochondria. However, the functional significance of these mitochondria-localized microproteins in energy-intensive organs such as the heart remains largely unexplored. In this study, we demonstrate that the long non-coding RNA CD63-AS1 encodes a mitochondrial microprotein. Notably, in ribosome profiling data of human hearts, there is a positive correlation between the expression of CD63-AS1 and genes associated with cardiomyopathy. We have termed this microprotein CEAM (CD63-AS1 encoded amyloid-like motif containing microprotein), reflecting its sequence characteristics. Our biochemical assays show that CEAM forms protease-resistant aggregates within mitochondria, whereas deletion of the amyloid-like motif transforms CEAM into a soluble cytosolic protein. Overexpression of CEAM triggers mitochondrial stress responses and adversely affect mitochondrial bioenergetics in cultured cardiomyocytes. In turn, the expression of CEAM is reciprocally inhibited by the activation of mitochondrial stresses induced by oligomycin. When expressed in mouse hearts via adeno-associated virus, CEAM impairs cardiac function. However, under conditions of pressure overload-induced cardiac hypertrophy, CEAM expression appears to offer a protective benefit and mitigates the expression of genes associated with cardiac remodeling, presumably through a mechanism that suppresses stress-induced translation reprogramming. Collectively, our study uncovers a hitherto unexplored amyloid-like microprotein expressed in the human cardiomyocytes, offering novel insights into myocardial hypertrophy pathophysiology.

Phloridzin prevents diabetic cardiomyopathy by reducing inflammation and oxidative stress

Oxidative stress and inflammation significantly contribute to the pathogenesis of diabetic cardiomyopathy (DCM). Persistent inflammatory stimuli drive the progression of myocardial fibrosis and impaired cardiac function. Phloridzin (Phl), a natural compound, demonstrates both anti-inflammatory and antioxidant properties. Nevertheless, its therapeutic potential and underlying mechanisms in DCM remain unclear. This study aimed to elucidate the mechanisms through which Phl inhibited myocardial fibrosis and exerted its antioxidative effects. The impact of Phl on DCM was evaluated using a high-fat/high-sugar diet combined with streptozotocin to induce an animal model and an in vitro H9C2 cell model stimulated by high glucose (HG). Untargeted metabolomics identified potential mechanisms underlying myocardial fibrosis. Phl treatment significantly enhanced left ventricular ejection fraction (EF%) and shortening fraction (FS%), while reducing myocardial injury markers, such as lactate dehydrogenase and creatine phosphokinase-MB, and suppressing myocardial collagen fiber accumulation. Simultaneously, Phl attenuated myocardial inflammation via inhibition of MyD88/NF-κB signaling, modulated the Nrf2/GPX4 axis to counter oxidative stress, and mitigated ferroptosis. In vitro, Phl inhibited high glucose-induced myocardial hypertrophy and fibrosis in H9C2 cells, while also repressing NF-κB activation in cardiomyocytes. Metabolomic profiling revealed that Phl ameliorated DCM through modulation of glycerophospholipid metabolic pathways, linking these metabolic shifts to enhanced antioxidant capacity, thereby reflecting its ability to reduce oxidative stress in the myocardium. Collectively, Phl provides cardioprotective effects by alleviating inflammation and oxidative damage.

Apelin-13's Actions in Controlling Hypertension-Related Cardiac Hypertrophy and the Expressions of Inflammatory Cytokines.

As a key molecule for improving cardiovascular diseases, Apelin-13 was surveyed in this work to explain its actions in controlling inflammation, pyroptosis, and myocardial hypertrophy. First, mouse models with myocardial hypertrophy were established. Then, assessments were made on the pathological variation in the heart of mouse, on the cardiac functions, as well as on the expressions of cardiac hypertrophy markers (β-MHC, ANP, and BNP), inflammatory factors (TNF-α, COX2, IL-6, ICAM-1, and VCAM-1), myocardial cell pyroptosis markers (NLRP3, ASC, c-caspase-1, and GSDMD-N), and Hippo pathway proteins (p-YAP, YAP, LATS1, and p-LATS1) by HE staining, echocardiography scanning, and western blot tests separately. The expressions of such inflammatory factors as in myocardial tissue were acquired by ELISA. After inducing the phenotype of H9c2 cell hypertrophy by noradrenaline, we used CCK-8 kits to know about the activity of H9c2 cells treated with Apelin-13, and performed ɑ-actinin staining to measure the changes in volumes of such cells. As unraveled through this work, Apelin-13 refrained the activation of the Hippo pathway, which in turn attenuated the hypertrophy, inflammation, and pyroptosis of myocardial tissue and H9c2 cells. Hence, Apelin-13 can be considered as a target for hypertension treatment.

Maternal ketone supplementation throughout gestation improves neonatal cardiac dysfunction caused by perinatal iron deficiency.

Iron deficiency (ID) is common during gestation and in early infancy and has been shown to adversely affect cardiac development and function, which could lead to lasting cardiovascular consequences. Ketone supplementation has been shown to confer cardioprotective effects in numerous disease models. Here, we tested the hypothesis that maternal ketone supplementation during gestation would mitigate cardiac dysfunction in ID neonates. Female Sprague-Dawley rats were fed an iron-restricted or iron-replete diet before and throughout pregnancy. Throughout gestation, iron-restricted dams were given either a daily subcutaneous injection of ketone solution (containing β-hydroxybutyrate [βOHB]) or saline (vehicle). Neonatal offspring cardiac function was assessed by echocardiography at postnatal days (PD)3 and 13. Hearts and livers were collected post-mortem for assessments of mitochondrial function and gene expression profiles of markers oxidative stress and inflammation. Maternal iron restriction caused neonatal anemia and asymmetric growth restriction at all time points assessed, and maternal βOHB treatment had no effect on these outcomes. Echocardiography revealed reduced ejection fraction despite enlarged hearts (relative to body weight) in ID offspring, resulting in impaired oxygen delivery, which was attenuated by maternal βOHB supplementation. Further, maternal ketone supplementation affected biochemical markers of mitochondrial function, oxidative stress and inflammation in hearts of neonates, implicating these pathways in the protective effects conferred by βOHB. In summary, βOHB supplementation confers protection against cardiac dysfunction in ID neonates and could have implications for the treatment of anemic babies.

Isolated non-immune-mediated second-degree atrioventricular block in the fetus: natural history and predictive factors for spontaneous recovery.

To determine the clinical course of fetal isolated non-immune-mediated second-degree atrioventricular block (AVB) and the factors associated with spontaneous recovery in these cases. Fetuses with isolated non-immune-mediated second-degree AVB were recruited prospectively between 2014 and 2022. These fetuses were divided into two groups: those which recovered spontaneously and those which did not. Maternal and fetal characteristics and intrauterine and postnatal outcomes were compared between the two groups. The study cohort included 20 fetuses with isolated non-immune-mediated second-degree AVB, diagnosed at a median gestational age of 22.0 (range, 17.0-35.0) weeks. In 12 fetuses, 1:1 atrioventricular conduction was restored spontaneously in utero and there was no recurrence during the postnatal follow-up period. In the remaining eight fetuses, second-degree AVB was maintained and, in six of these, the pregnancy was terminated on parental request. Of the two liveborn children who had persistent second-degree AVB prenatally, one had progressed to complete AVB at the latest follow-up, at the age of 34 months, but was asymptomatic, without heart enlargement or dysfunction. The other child progressed to complete AVB after delivery and was diagnosed with type-2 long QT syndrome. This infant died aged 2 months. Fetuses in the group that recovered spontaneously had earlier gestational age at diagnosis (median, 20.0 (range, 17.0-26.0) vs 24.5 (range, 18.0-35.0) weeks; P = 0.004) and higher atrial rate at diagnosis (median, 147 (range, 130-160) vs 138 (range, 125-149) bpm; P = 0.006) in comparison with the group that did not recover spontaneously. The best cut-off values for prediction of failure to recover spontaneously were 22.5 weeks' gestational age at diagnosis and 144 bpm atrial rate at diagnosis, with sensitivities of 87.5% and 75.0%, respectively, and specificities of 92.0% and 87.5%, respectively. The outcome of 60% of fetuses with isolated non-immune-mediated second-degree AVB was favorable. Earlier gestational age and higher atrial rate at diagnosis were associated with spontaneous reversion to normal sinus rhythm. Prenatal genetic testing should be performed in cases with persistent AVB, to exclude heritable disorders including long QT syndrome. These findings provide important information for clinical management and prenatal counseling in these cases. © 2024 International Society of Ultrasound in Obstetrics and Gynecology.

Role of KLF4 and SIAT7A interaction accelerates myocardial hypertrophy induced by Ang II.

Sialylation catalysed by sialyltransferase 7A (SIAT7A) plays a role in the development of cardiac hypertrophy. However, the regulatory mechanisms upstream of SIAT7A in this context remain poorly elucidated. Previous study demonstrated that KLF4 activates the SIAT7A gene in ischemic myocardium by binding to its promoter region. Nevertheless, the potential involvement of KLF4 in regulating SIAT7A expression in Ang II-induced hypertrophic cardiomyocytes remains uncertain. This study seeks to deepen the underlying mechanisms of the KLF4 and SIAT7A interaction in the progression of Ang II-induced cardiac hypertrophy. The results showed a concurrent increase in SIAT7A and KLF4 levels in hypertrophic myocardium of essential hypertension patients and in hypertrophic cardiomyocytes stimulated by Ang II. Invitro experiments revealed that reducing KLF4 levels led to a decrease in both SIAT7A synthesis and Sialyl-Tn antigen expression, consequently inhibiting Ang II-induced cardiomyocyte hypertrophy. Intriguingly, reducing SIAT7A levels also resulted in decreased KLF4 expression and suppression cardiomyocyte hypertrophy. Consistent with this, elevating SIAT7A levels increased KLF4 expression and exacerbated cardiomyocyte hypertrophy in both invivo and invitro experiments. Additionally, a time-course analysis indicated that KLF4 expression preceded that of SIAT7A. Luciferase reporter assays further confirmed that modulating SIAT7A levels directly influenced the transcriptional activity of KLF4 in cardiomyocytes. In summary, KLF4 expression is upregulated in cardiomyocytes treated with Ang II, which subsequently induces the expression of SIAT7A. The elevated levels of SIAT7A, in turn, enhance the transcription of KLF4. These findings suggest a positive feedback loop between KLF4 and SIAT7A-Sialyl-Tn, ultimately promoting Ang II-induced cardiac hypertrophy.

Tinglu Yixin granule inhibited fibroblast-myofibroblast transdifferentiation to ameliorate myocardial fibrosis in diabetic mice

Ethnopharmacological relevanceMyocardial fibrosis is one of the pathological characteristics of advanced diabetic cardiomyopathy (DCM) and serves as the strong evidence of poor prognosis. Among them, the transdifferentiation of cardiac fibroblasts (CFs) may play a crucial role in the development of myocardial fibrosis in DCM. Tinglu Yixin granule (TLYXG) has been clinically used for many years and can significantly improve cardiac function of patients with DCM. However, the effect of TLYXG on myocardial fibrosis in DCM remains unknown, and the underlying mechanisms of its efficacy have yet to be fully understood. Aim of the studyThis study aimed to investigate the impact and underlying mechanism of TLYXG on myocardial fibrosis in diabetes mice. Materials and methodsThe bioactive compounds in TLYXG were identified using ultra-performance liquid chromatography-mass spectrometry (UPLC-MS). The potential mechanism of TLYXG in treating DCM was predicted using network pharmacology combined with molecular docking and protein-protein docking. The mice model of type 2 diabetes were established by intraperitoneal injection of streptozotocin (STZ) and the high-fat diet (HFD). Indicators of pancreatic islet function, lipids, oxidative stress, and inflammatory factors were tested using kits. Cardiac function was assessed in diabetic mice using echocardiography. Histologic staining was performed to evaluate myocardial hypertrophy and fibrosis. Mechanistically, the hypothesis was tested through rescue experiments. The expression levels of transient receptor potential channel 6 (TRPC6), transforming growth factor-β1 (TGF-β1), collagen I (COL-I) and alpha-smooth muscle actin (α-SMA), along with the mRNA and phosphorylation levels of SMAD family member 3 (Smad3) and protein 38 mitogen-activated protein kinase (p38 MAPK), were assessed using quantitative RT-qPCR, western blot, immunohistochemistry, and immunofluorescence. Neonatal lactating mice were used to extract primary CFs for vitro experiments. Scratch and transwell assays were conducted to assess CFs migration and invasion abilities. Western blot and immunofluorescence were used to evaluate the expression levels of CFs transdifferentiation markers COL-I and α-SMA. ResultsA total of 168 active ingredients were detected in TLYXG based on UPLC-MS and databases. Network pharmacology indicated that TLYXG could improve DCM through inflammatory mediator regulation of TRP channels, TGF-beta signaling pathway, and MAPK signaling pathway. ELISA results showed that TLYXG could ameliorate metabolic levels, inflammation, and oxidative stress in diabetic mice. Echocardiography suggested that TLYXG improved cardiac systolic and diastolic dysfunction in diabetic mice. Histological analysis revealed that TLYXG alleviated myocardial fibrosis in diabetes mice. Additionally, molecular docking analysis indicated strong binding activity between the main active ingredients of TLYXG and TRPC6 of the TRP family. At the molecular level, TLYXG reduced the mRNA and protein expression levels of TRPC6 and TGF-β1 and inhibited the mRNA and phosphorylation levels of Smad3 and p38 MAPK. Furthermore, TLYXG inhibited CFs migration and invasion, and reduced the expression levels of the CFs transdifferentiation markers COL-I and α-SMA. ConclusionTLYXG inhibited the proliferation, migration, invasion and transdifferentiation of CFs by suppressing TGF-β1/Smad3/p38 MAPK signaling through down-regulation of TRPC6, thereby ameliorating myocardial fibrosis in diabetes mice.