Response Of Cardiomyocytes Research Articles

MG53 alleviates hypoxia/reoxygenation-induced cardiomyocyte injury by succinylation and ubiquitination modification

ABSTRACT Background Mitsugumin 53 (MG53) is a membrane repair factor that is associated with acute myocardial infarction. This study aimed to investigate the effects of MG53 on cardiomyocyte injury and the posttranslational modification of MG53. Methods Cardiomyocyte injury was evaluated by enzyme-linked immunosorbent assay and flow cytometry. The succinylation and ubiquitination levels of MG53 were examined by immunoprecipitation (IP) and western blot. The relationship between MG53 and KAT3B or SIRT7 was assessed by co-IP and immunofluorescence. Results The results showed that overexpression of MG53 inhibited inflammation response and apoptosis of cardiomyocytes induced by hypoxia/reoxygenation (H/R). Succinylation and protein levels of MG53 were downregulated in H/R-induced cells, which was inhibited by SIRT7 and promoted by KAT3B. SIRT7 aggravated and KAT3B alleviated MG53-mediated cardiomyocyte injury. Moreover, MG53 was succinylated and ubiquitinated at K130. Conclusion SIRT7 inhibited/KAT3B promoted succinylation of MG53 at K130 sites, which suppressed ubiquitination of MG53 and upregulated its protein levels, thereby alleviating H/R-induced cardiomyocyte injury. The findings suggested that MG53 may be a potential therapy for myocardial infarction.

Exploring the efficacy of Shexiang Tongxin extract pills in severe heart failure

The clinical efficacy of Shexiang Tongxin pills (STP) on cardiac function, inflammation, and prognosis was investigated in patients with severe heart failure. A total of 140 patients with severe heart failure, diagnosed and treated at the Shaoxing Central Hospital and its affiliates, were divided into control and experimental groups. Patients in the control group received conventional treatment, while those in the experimental group were given STP plus conventional treatment. The cardiac functions, levels of inflammatory factors, and outcomes of 6-minute walk distance (6MWD) were assessed and compared after 12 weeks of intervention. Besides, the rehospitalization and mortality proportions were also determined during a 1-year follow-up. In addition, oxygen-glucose deprivation and reperfusion (OGD/R) were conducted to mimic the injury of H9c2 cells in heart failure; cell survival, cytotoxicity, apoptosis, and inflammatory factors were also evaluated. Post-intervention, patients in the experiment group demonstrated greater improvement in cardiac functions, especially regarding left ventricular end-diastolic diameter and N-terminal pro-B-type natriuretic peptide, which were significantly decreased, while left ventricular ejection fraction was significantly increased (P < 0.05). Further, the levels of inflammatory factors, including tumor necrosis factor-α, hypersensitive C-reactive-protein, and interleukin 6, were significantly lower (P < 0.05), and a superior 6MWD outcome was observed in patients from the experimental group, compared to the control group (P < 0.05). After 1-year follow-up, both rehospitalization rate and mortality were significantly decreased in the experimental group, compared to the control group (rehospitalization, 38.57% vs. 55.71%, and mortality, 12.86% vs. 27.14%, respectively; P < 0.05). Furthermore, STP increased cell survival and reduced cell apoptosis, cytotoxicity, and inflammatory response in cardiomyocytes induced by OGD/R. Shexiang Tongxin pill demonstrated significant and promising clinical effects in treating severe heart failure by ameliorating cardiac functions, reducing inflammatory factor levels, and improving patients’ prognosis. In addition, STP ameliorated cellular damage and inflammation at cellular level. Thus, STP demonstrated important clinical values.

The interplay between H19 and HIF-1α in mitochondrial dysfunction in myocardial infarction

Myocardial infarction(MI) causes prolonged ischemia of infarcted myocardial tissue, which triggers a wide range of hypoxia cellular responses in cardiomyocytes. Emerging evidence has indicated the critical roles of long non-coding RNAs(lncRNAs) in cardiovascular diseases, including MI. The purpose of this study was to investigate the roles of lncRNA H19 and H19/HIF-1α pathway during MI. Results showed that cell injury and mitochondrial dysfunction were induced in hypoxia-treated H9c2 cells, accompanied by an increase in the expression of H19. H19 silencing remarkably diminishes cell injury, inhibits the dysfunctional degree of mitochondria, and decreases the injury of MI rats. Bioinformatics analysis and dual-luciferase assays revealed that H19 was the hypoxia-responsive lncRNA, and HIF-1α induced H19 transcription through direct binding to the H19 promoter. Moreover, H19 participates in the HIF-1α pathway by stabilizing the HIF-1α protein. These results indicated that H19 might be a potential biomarker and therapeutic target for myocardial infarction.

Self-recruited neutrophils trigger over-activated innate immune response and phenotypic change of cardiomyocytes in fulminant viral myocarditis

Fulminant myocarditis (FM) is a life-threatening inflammatory disease. However, the mechanisms underlying its acute onset are unknown. By dynamic cardiac function measurement, we discovered that the initiation of sudden hemodynamic collapse was on day 4 in the mouse model of FM. Single-cell RNA-sequencing study revealed that healthy cardiomyocytes (CMs) lost their contractile and metabolic function and differentiated into pro-angiogenic and pro-inflammatory CMs. Meanwhile, neutrophils, the most expanded immune cells, exhibited a unique developmental trajectory only after migrating to the heart, where they continuously attracted peripheral neutrophils via Cxcl2/Cxcl3, resulting in the acute accumulation of neutrophils in the heart. Well-differentiated cardiac-infiltrating neutrophils, rather than viruses, induced phenotypic changes in CMs. Moreover, neutrophils could amplify cytokine storm by recruiting and activating pro-inflammatory monocytes. Blockade of the self-recruiting loop of neutrophils by targeting the Cxcl2/Cxcl3-Cxcr2 axis substantially alleviated FM in mice. Collectively, we provide a comprehensive single-cell atlas of immune cells and CMs in FM, elucidate the disease pathogenesis, and suggest potential therapeutic strategies.

Myogenetic Oligodeoxynucleotide Induces Myocardial Differentiation of Murine Pluripotent Stem Cells.

An 18-base myogenetic oligodeoxynucleotide (myoDN), iSN04, acts as an anti-nucleolin aptamer and induces myogenic differentiation of skeletal muscle myoblasts. This study investigated the effect of iSN04 on murine embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs). In the undifferentiated state, iSN04 inhibited the proliferation of ESCs and iPSCs but did not affect the expression of pluripotent markers. In the differentiating condition, iSN04 treatment of ESCs/iPSCs from day 5 onward dramatically induced differentiation into Nkx2-5+ beating cardiomyocytes with upregulation of Gata4, Isl1, and Nkx2-5, whereas iSN04 treatment from earlier stages completely inhibited cardiomyogenesis. RNA sequencing revealed that iSN04 treatment from day 5 onward contributes to the generation of cardiac progenitors by modulating the Wnt signaling pathway. Immunostaining showed that iSN04 suppressed the cytoplasmic translocation of nucleolin and restricted it to the nucleoli. These results demonstrate that nucleolin inhibition by iSN04 facilitates the terminal differentiation of cardiac mesoderm into cardiomyocytes but interferes with the differentiation of early mesoderm into the cardiac lineage. This is the first report on the generation of cardiomyocytes from pluripotent stem cells using a DNA aptamer. Since iSN04 did not induce hypertrophic responses in primary-cultured cardiomyocytes, iSN04 would be useful and safe for the regenerative therapy of heart failure using stem cell-derived cardiomyocytes.

Flagellin-Induced Immune Response in Human-Induced Pluripotent Stem Cell-Derived Cardiomyocytes.

Pathogen-associated molecular patterns (PAMPs) are involved in the pathogenesis of septic cardiomyopathy through a toll-like receptor (TLR)-mediated immune response. Human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) can reflect the innate immune abilities of cardiomyocytes. Therefore, hiPSC-CMs may provide an attractive tool with which to study PAMP-induced alterations in cardiomyocytes. HiPSC-CMs from two different healthy donors were exposed to the PAMP flagellin (FLA) at different doses and exposure times. Alterations in the expression levels of distinct inflammation-associated cytokines, intracellular inflammation pathways including TLR5 downstream signaling, reactive oxygen species levels and surface antigen composition were assessed using PCR, ELISA and FACS techniques. Higher doses of flagellin increased the expression levels of inflammation-associated cytokines like TNFα (p < 0.01) and downstream signaling molecules like caspase-8 (p < 0.05). TLR5 expression (p < 0.01) and TLR5 fluorescence proportion (p < 0.05) increased in hiPSC-CMs after prolonged FLA exposure. FLA-induced innate immune response processes in cardiomyocytes might be detectable with an hiPSC-CMs-based in vitro model.

Electrically stimulated in vitro heart cell mimic of acute exercise reveals novel immediate cellular responses to exercise: Reduced contractility and metabolism, but maintained calcium cycling and increased myofilament calcium sensitivity.

Cardiac cellular responses to acute exercise remain undescribed. We present a model for mimicking acute aerobic endurance exercise to freshly isolated cardiomyocytes by evoking exercise-like contractions over prolonged periods of time with trains of electrical twitch stimulations. We then investigated immediate contractile, Ca2+ , and metabolic responses to acute exercise in perfused freshly isolated left ventricular rat cardiomyocytes, after a matrix-design optimized protocol and induced a mimic for acute aerobic endurance exercise by trains of prolonged field twitch stimulations. Acute exercise decreased cardiomyocyte fractional shortening 50%-80% (p < .01). This was not explained by changes to intracellular Ca2+ handling (p > .05); rather, we observed a weak insignificant Ca2+ transient increase (p = .11), while myofilament Ca2+ sensitivity increased 20%-70% (p < .05). Acidic pH 6.8 decreased fractional shortening 20%-70% (p < .05) because of 20%-30% decreased Ca2+ transients (p < .05), but no difference occurred between control and acute exercise (p > .05). Addition of 1 or 10 mM La- increased fractional shortening in control (1 mM La- : no difference, p > .05; 10 mM La- : 20%-30%, p < .05) and acute exercise (1 mM La- : 40%-90%, p < .01; 10 mM La- : 50%-100%, p < .01) and rendered acute exercise indifferent from control (p > .05). Intrinsic autofluorescence showed a resting NADstate of 0.59 ± 0.04 and FADstate of 0.17 ± 0.03, while acute exercise decreased NADH/FAD ratio 8% (p < .01), indicating intracellular oxidation. In conclusion, we show a novel approach for studying immediate acute cardiomyocyte responses to aerobic endurance exercise. We find that acute exercise in cardiomyocytes decreases contraction, but Ca2+ handling and myofilament Ca2+ sensitivity compensate for this, while acidosis and reduced energy substrate and mitochondrial ATP generation explain this.

Abscisic Acid and Its Receptors LANCL1 and LANCL2 Control Cardiomyocyte Mitochondrial Function, Expression of Contractile, Cytoskeletal and Ion Channel Proteins and Cell Proliferation via ERRα.

The cross-kingdom stress hormone abscisic acid (ABA) and its mammalian receptors LANCL1 and LANCL2 regulate the response of cardiomyocytes to hypoxia by activating NO generation. The overexpression of LANCL1/2 increases transcription, phosphorylation and the activity of eNOS and improves cell vitality after hypoxia/reoxygenation via the AMPK/PGC-1α axis. Here, we investigated whether the ABA/LANCL system also affects the mitochondrial oxidative metabolism and structural proteins. Mitochondrial function, cell cycle and the expression of cytoskeletal, contractile and ion channel proteins were studied in H9c2 rat cardiomyoblasts overexpressing or silenced by LANCL1 and LANCL2, with or without ABA. Overexpression of LANCL1/2 significantly increased, while silencing conversely reduced the mitochondrial number, OXPHOS complex I, proton gradient, glucose and palmitate-dependent respiration, transcription of uncoupling proteins, expression of proteins involved in cytoskeletal, contractile and electrical functions. These effects, and LANCL1/2-dependent NO generation, are mediated by transcription factor ERRα, upstream of the AMPK/PGC1-α axis and transcriptionally controlled by the LANCL1/2-ABA system. The ABA-LANCL1/2 hormone-receptor system controls fundamental aspects of cardiomyocyte physiology via an ERRα/AMPK/PGC-1α signaling axis and ABA-mediated targeting of this axis could improve cardiac function and resilience to hypoxic and dysmetabolic conditions.

Loss and recovery of myocardial mitochondria in mice under different tail suspension time: Apoptosis and mitochondrial fission, fusion and autophagy.

Long-term weightlessness in animals can cause changes in myocardial structure and function, in which mitochondria play an important role. Here, a tail suspension (TS) Kunming mouse (Mus musculus) model was used to simulate the effects of weightlessness on the heart. We investigated the effects of 2 and 4weeks of TS (TS2 and TS4) on myocardial mitochondrial ultrastructure and oxidative respiratory function and on the molecular mechanisms of apoptosis and mitochondrial fission, autophagy and fusion-related signalling. Our study revealed significant changes in the ultrastructural features of cardiomyocytes in response to TS. The results showed: (1) mitochondrial swelling and disruption of cristae in TS2, but mitochondrial recovery and denser cristae in TS4; (2) an increase in the total number of mitochondria and number of sub-mitochondria in TS4; (3) no significant changes in the nuclear ultrastructure or DNA fragmentation among the two TS groups and the control group; (4) an increase in the bax/bcl-2 protein levels in the two TS groups, indicating increased activation of the bax-mediated apoptosis pathway; (5) no change in the phosphorylation ratio of dynamin-related protein 1 in the two TS groups; (6) an increase in the protein levels of optic atrophy 1 and mitofusin 2 in the two TS groups; and (7) in comparison to the TS2 group, an increase in the phosphorylation ratio of parkin and the ratio of LC3II to LC3I in TS4, suggesting an increase in autophagy. Taken together, these findings suggest that mitochondrial autophagy and fusion levels increased after 4weeks of TS, leading to a restoration of the bax-mediated myocardial apoptosis pathway observed after 2weeks of TS. NEW FINDINGS: What is the central question of this study? What are the effects of 2 and 4weeks of tail suspension on myocardial mitochondrial ultrastructure and oxidative respiratory function and on the molecular mechanisms of apoptosis and mitochondrial fission, autophagy and fusion-related signalling? What is the main finding and its importance? Increased mitochondrial autophagy and fusion levels after 4weeks of tail suspension help to reshape the morphology and increase the number of myocardial mitochondria.

MST1 mediates doxorubicin-induced cardiomyopathy by SIRT3 downregulation

Heart failure is a major side effect of doxorubicin (DOX) treatment in patients with cancer. However, the mechanisms underlying the development of DOX-induced heart failure need to be addressed. This study aims to test whether the serine/threonine kinase MST1, a major Hippo pathway component, contributes to the development of DOX-induced myocardial injury. C57BL/6J WT mice and mice with cardiomyocyte-specific dominant-negative MST1 (kinase-dead) overexpression received three weekly injections of DOX, reaching a final cumulative dose of 18 mg/kg. Echocardiographic, histological and biochemical analyses were performed six weeks after the first DOX administration. The effects of MST1 inhibition on DOX-induced cardiomyocyte injury were also tested in vitro. MST1 signaling was significantly activated in cardiomyocytes in response to DOX treatment in vitro and in vivo. Wild-type (WT) mice treated with DOX developed cardiac dysfunction and mitochondrial abnormalities. However, these detrimental effects were abolished in mice with cardiomyocyte-specific overexpression of dominant-negative MST1 (DN-MST1) or treated with XMU-MP-1, a specific MST1 inhibitor, indicating that MST1 inhibition attenuates DOX-induced cardiac dysfunction. DOX treatment led to a significant downregulation of cardiac levels of SIRT3, a deacetylase involved in mitochondrial protection, in WT mice, which was rescued by MST1 inhibition. Pharmacological inhibition of SIRT3 blunted the protective effects of MST1 inhibition, indicating that SIRT3 downregulation mediates the cytotoxic effects of MST1 activation in response to DOX treatment. Finally, we found a significant upregulation of MST1 and downregulation of SIRT3 levels in human myocardial tissue of cancer patients treated with DOX. In summary, MST1 contributes to DOX-induced cardiomyopathy through SIRT3 downregulation.

Indole-3-propionic acid, a product of intestinal flora, inhibits the HDAC6/NOX2 signaling and relieves doxorubicin-induced cardiomyocyte damage.

The heart failure-gut hypothesis indicates that damage to intestinal mucosa leads to increased microbial translocation, resulting in alterations in metabolites entering the blood circulation. This process promotes the development of heart failure. This study aimed to reveal the involvement of indole-3-propionic acid (IPA), a microbiota-derived tryptophan metabolite, in heart failure. Human cardiomyocytes AC16 was treated with doxorubicin to induce in vitro heart failure model, the influences of IPA on the cellular viability, apoptosis, inflammation and oxidative stress were evaluated. Molecular docking and western blotting were used to initially illustrate the potential relationship between IPA and HDAC6. Through HDAC6 overexpression, its mediating role in the regulatory mechanism of IPA in the above aspects was further investigated. IPA was found to reduce the apoptosis, inflammation and oxidative stress in doxorubicin-treated cells. The visualized structure displayed that IPA bound to HDAC6 and that IPA reduced HDAC6 level. Additionally, HDAC6 overexpression reversed the regulation of IPA in the above aspects, indicating the HDAC6/NOX2 signals mediated the mechanism of IPA. Together, the present study revealed that IPA reduced oxidative stress, inflammatory response and apoptosis in cardiomyocytes via inhibiting the HDAC6/NOX2 signaling. The findings suggest that gut microbiota metabolites have potential in the treatment of heart failure.

Comparative microRNA profiling of Trypanosoma cruzi infected human cells.

Trypanosoma cruzi, the causative agent of Chagas disease, can infect almost any nucleated cell in the mammalian host. Although previous studies have described the transcriptomic changes that occur in host cells during parasite infection, the understanding of the role of post-transcriptional regulation in this process is limited. MicroRNAs, a class of short non-coding RNAs, are key players in regulating gene expression at the post-transcriptional level, and their involvement in the host-T. cruzi interplay is a growing area of research. However, to our knowledge, there are no comparative studies on the microRNA changes that occur in different cell types in response to T. cruzi infection. Here we investigated microRNA changes in epithelial cells, cardiomyocytes and macrophages infected with T. cruzi for 24 hours, using small RNA sequencing followed by careful bioinformatics analysis. We show that, although microRNAs are highly cell type-specific, a signature of three microRNAs -miR-146a, miR-708 and miR-1246, emerges as consistently responsive to T. cruzi infection across representative human cell types. T. cruzi lacks canonical microRNA-induced silencing mechanisms and we confirm that it does not produce any small RNA that mimics known host microRNAs. We found that macrophages show a broad response to parasite infection, while microRNA changes in epithelial and cardiomyocytes are modest. Complementary data indicated that cardiomyocyte response may be greater at early time points of infection. Our findings emphasize the significance of considering microRNA changes at the cellular level and complement previous studies conducted at higher organizational levels, such as heart samples. While miR-146a has been previously implicated in T. cruzi infection, similarly to its involvement in many other immunological responses, miR-1246 and miR-708 are demonstrated here for the first time. Given their expression in multiple cell types, we anticipate our work as a starting point for future investigations into their role in the post-transcriptional regulation of T. cruzi infected cells and their potential as biomarkers for Chagas disease.

L-Carnitine improves mechanical responses of cardiomyocytes and restores Ca2+ homeostasis during aging.

L-Carnitine (β-hydroxy-γ-trimethylaminobutyric acid, LC) is a crucial molecule for the mitochondrial oxidation of fatty acids. It facilitates the transport of long-chain fatty acids into the mitochondrial matrix. The reduction in LC levels during the aging process has been linked to numerous cardiovascular disorders, including contractility dysfunction, and disrupted intracellular Ca2+ homeostasis. The aim of this study was to examine the effects of long-term (7months) LC administration on cardiomyocyte contraction and intracellular Ca2+ transients ([Ca2+]i) in aging rats. Male albino Wistar rats were randomly assigned to either the control or LC-treated groups. LC (50mg/kg body weight/day) was dissolved in distilled water and orally administered for a period of 7months. The control group received distilled water alone. Subsequently, ventricular single cardiomyocytes were isolated, and the contractility and Ca2+ transients were recorded in aging (18months) rats. This study demonstrates, for the first time, a novel inotropic effect of long-term LC treatment on rat ventricular cardiomyocyte contraction. LC increased cardiomyocyte cell shortening and resting sarcomere length. Furthermore, LC supplementation led to a reduction in resting [Ca2+]i level and an increase in the amplitude of [Ca2+]i transients, indicative of enhanced contraction. Consistent with these results, decay time of Ca2+ transients also decreased significantly in the LC-treated group. The long-term administration of LC may help restore the Ca2+ homeostasis altered during aging and could be used as a cardioprotective medication in cases where myocyte contractility is diminished.

Prognostic Value of sST2 in Heart Failure.

In recent years, there has been growing interest in the risk stratification for heart failure, and the use of multiple biomarkers to identify different pathophysiological processes associated with this condition. One such biomarker is soluble suppression of tumorigenicity-2 (sST2), which has shown some potential for integration into clinical practice. sST2 is produced by both cardiac fibroblasts and cardiomyocytes in response to myocardial stress. Other sources of sST2 are endothelial cells of the aorta and coronary arteries and immune cells such as T cells. Indeed, ST2 is also associated with inflammatory and immune processes. We aimed at reviewing the prognostic value of sST2 in both chronic and acute heart failure. In this setting, we also provide a flowchart about its potential use in clinical practice.

ROLE OF UBIQUITINYLATION MODIFICATION OF SIRTUIN 3 IN HYPERTENSION-ASSOCIATED CARDIOMYOCYTE INJURY

Objective: The present study was designed to investigate whether mitochondrial dysfunction and oxidative stress in HTN-injured cardiomyocytes are associated with SIRT3 ubiquitination and whether SIRT3 deubiquitination can ameliorate the related cardiomyocyte injury. Design and method: The human cardiomyocyte AC16 cell line was selected as the study target. The SIRT3-K288R cell line construction was verified by immunoprecipitation and the effect of Ang-II on SIRT3 class ubiquitination was explored; the expression of SOD2, Acetyl-SOD2 (MnSOD), protein acetylation level, inflammatory vesicles NLRP3, etc. in different subgroups were determined by Western Blot to explore the ubiquitination-like modifications and SIRT3 deacetylation in HTN-related cell injury Results: (1) Immunoprecipitation results showed that the level of SIRT3 class ubiquitination was reduced after SIRT3-K288R transfection; compared to the control group, the level of SIRT3 class ubiquitination was increased in the presence of AngII; (2) Western Blot results showed that compared to the HTN cell injury model, the cardiomyocytes in the SIRT3-K288R intervention group had increased Acetyl- SOD2/SOD2 levels were increased (p &lt; 0.05) and protein acetylation levels were decreased in the SIRT3-K288R intervention group compared with the HTN cell injury model, indicating that SIRT3 deubiquitination increased the deacetylation effect on mitochondria and increased cellular antioxidant stress enzyme activity; (3) Western Blot results showed that compared with the HTN cell injury model, cardiomyocytes in the SIRT3-K288R intervention group NLRP3 and NOX4 levels were significantly reduced, indicating that SIRT3 deubiquitination could improve the inflammatory response to Ang-II-related cell injury. Conclusions: In the HTN-associated cell injury model, the level of SIRT3 class ubiquitination was significantly increased, and the removal of ubiquitination modification by viral transfection could improve oxidative stress, protein acetylation levels and associated inflammatory responses in HTN-injured cardiomyocytes, indicating that SIRT3 class ubiquitination may play an important mechanism in HTN-associated cell injury, and reducing SIRT3 class ubiquitination modification may be a possible direction for future research.

Focal adhesion kinase induces cardiac remodeling through NF-κB-mediated inflammatory responses in diabetic cardiomyopathy

BackgroundHyperglycemia-induced chronic inflammation is a crucial risk factor that causes undesirable cardiac alternations in diabetic cardiomyopathy (DCM). Focal adhesion kinase (FAK) is a non-receptor protein tyrosine kinase that primarily regulates cell adhesion and migration. Based on recent studies, FAK is involved in inflammatory signaling pathway activation in cardiovascular diseases. Here, we evaluated the possibility of FAK as a therapeutic target for DCM. MethodsA small molecular selective FAKinhibitor, PND-1186 (PND), was used to evaluate the effect of FAK on DCM in both high glucose-stimulated cardiomyocytes and streptozotocin (STZ)-induced type 1 diabetes mellitus (T1DM) mice. ResultsIncreased FAK phosphorylation was found in the hearts of STZ-induced T1DM mice. PND treatment significantly decreased the expression of inflammatory cytokines and fibrogenic markers in cardiac specimens of diabetic mice. Notably, these reductions were correlated with improved cardiac systolic function. Furthermore, PND suppressed transforming growth factor-β-activated kinase 1 (TAK1) phosphorylation and NF-κB activation in the hearts of diabetic mice. Cardiomyocytes were identified as the main contributor to FAK-mediated cardiac inflammation and the involvement of FAK in cultured primary mouse cardiomyocytes and H9c2 cells was identified. Both FAK inhibition or FAK deficiency prevented hyperglycemia-induced inflammatory and fibrotic responses in cardiomyocytes owing to the inhibition of NF-κB. Herein, FAK activation was revealed to FAK directly binding to TAK1, leading to activation of TAK1 and downstream NF-κB signaling pathway. ConclusionsFAK is a key regulator of diabetes-associated myocardial inflammatory injury by directly targeting to TAK1.

SARS-CoV-2 induces cardiomyocyte apoptosis and inflammation but can be ameliorated by ACE inhibitor Captopril

Although the clinical manifestation of COVID-19 is mainly respiratory symptoms, approximately 20% of patients suffer from cardiac complications. COVID-19 patients with cardiovascular disease have higher severity of myocardial injury and poor outcomes. The underlying mechanism of myocardial injury caused by SARS-CoV-2 infection remains unclear. Using a non-transgenic mouse model infected with Beta variant (B.1.351), we found that the viral RNA could be detected in lungs and hearts of infected mice. Pathological analysis showed thinner ventricular wall, disorganized and ruptured myocardial fiber, mild inflammatory infiltration, and mild epicardia or interstitial fibrosis in hearts of infected mice. We also found that SARS-CoV-2 could infect cardiomyocytes and produce infectious progeny viruses in human pluripotent stem cell-derived cardiomyocyte-like cells (hPSC-CMs). SARS-CoV-2 infection caused apoptosis, reduction of mitochondrial integrity and quantity, and cessation of beating in hPSC-CMs. In order to dissect the mechanism of myocardial injury caused by SARS-CoV-2 infection, we employed transcriptome sequencing of hPSC-CMs at different time points after viral infection. Transcriptome analysis showed robust induction of inflammatory cytokines and chemokines, up-regulation of MHC class I molecules, activation of apoptosis signaling and cell cycle arresting. These may cause aggravate inflammation, immune cell infiltration, and cell death. Furthermore, we found that Captopril (hypotensive drugs targeting ACE) treatment could alleviate SARS-CoV-2 induced inflammatory response and apoptosis in cardiomyocytes via inactivating TNF signaling pathways, suggesting Captopril may be beneficial for reducing COVID-19 associated cardiomyopathy. These findings preliminarily explain the molecular mechanism of pathological cardiac injury caused by SARS-CoV-2 infection, providing new perspectives for the discovery of antiviral therapeutics.

NT-proBNP in Different Patient Groups of COPD: A Systematic Review and Meta-Analysis.

NT-proBNP, a peptide biomarker synthesized and secreted by cardiomyocytes in response to cardiac load, has gained attention in recent years for its potential role in respiratory diseases. Chronic Obstructive Pulmonary Disease (COPD), a chronic and progressive inflammatory condition affecting the respiratory system, is frequently associated with comorbidities involving the cardiovascular system. Consequently, the aim of this systematic review and meta-analysis was to evaluate the variations in NT-proBNP levels across distinct patient groups with COPD and establish a foundation for future investigations into the precise clinical significance of NT-proBNP in COPD. The search databases for this study were conducted in PubMed, Excerpt Medica database (Embase), Web of Science (WOS), and Cochrane Library databases. Databases were searched for studies on the predictive value of NT-proBNP in adult COPD patients. A total of 29 studies (8534 participants) were included. Patients with stable COPD exhibit elevated levels of NT-proBNP [standardized mean difference(SMD) [95CI%]=0.51 [0.13,0.89]; p=0.0092]. COPD patients with predicted forced expiratory volume in 1 s (FEV1) < 50% exhibit significantly elevated levels of NT-proBNP compared to those with FEV1 ⩾50%[SMD [95CI%]=0.17 [0.05,0.29]; p=0.0058]. NT-proBNP levels were significantly higher in acute exacerbations (AECOPD) compared to patients with stable COPD [SMD [95CI%]=1.18 [0.07,2.29]; p=0.037]. NT-proBNP levels was significantly higher in non-survivors than in survivors of hospitalised AECOPD patients [SMD [95CI%]=1.67 [0.47,2.88]; p=0.0063]. Both COPD patients with pulmonary hypertension(PH) [SMD [95CI%]=0.82 [0.69,0.96]; p<0.0001] and chronic heart failure(CHF) [SMD [95CI%]=1.49 [0.96,2.01]; p<0.0001] showed higher NT-proBNP level. NT-proBNP, a biomarker commonly used in clinical practice to evaluate cardiovascular disease, demonstrates significant variations in different stages of COPD and during the progression of the disease. The fluctuations in NT-proBNP levels could be indicative of the severity of pulmonary hypoxia and inflammation and cardiovascular stress among COPD patients. Therefore, assessing NT-proBNP levels in COPD patients can aid in making informed clinical decisions.

Pressure overload induces ISG15 to facilitate adverse ventricular remodeling and promote heart failure.

Inflammation promotes adverse ventricular remodeling, a common antecedent of heart failure. Here, we set out to determine how inflammatory cells affect cardiomyocytes in the remodeling heart. Pathogenic cardiac macrophages induced an IFN response in cardiomyocytes, characterized by upregulation of the ubiquitin-like protein IFN-stimulated gene 15 (ISG15), which posttranslationally modifies its targets through a process termed ISGylation. Cardiac ISG15 is controlled by type I IFN signaling, and ISG15 or ISGylation is upregulated in mice with transverse aortic constriction or infused with angiotensin II; rats with uninephrectomy and DOCA-salt, or pulmonary artery banding; cardiomyocytes exposed to IFNs or CD4+ T cell-conditioned medium; and ventricular tissue of humans with nonischemic cardiomyopathy. By nanoscale liquid chromatography-tandem mass spectrometry, we identified the myofibrillar protein filamin-C as an ISGylation target. ISG15 deficiency preserved cardiac function in mice with transverse aortic constriction and led to improved recovery of mouse hearts ex vivo. Metabolomics revealed that ISG15 regulates cardiac amino acid metabolism, whereas ISG15 deficiency prevented misfolded filamin-C accumulation and induced cardiomyocyte autophagy. In sum, ISG15 upregulation is a feature of pathological ventricular remodeling, and protein ISGylation is an inflammation-induced posttranslational modification that may contribute to heart failure development by altering cardiomyocyte protein turnover.

The response of fetal sheep cardiomyocytes to intralipid infusion

Introduction: The developing heart undergoes changes in metabolic substrates parallel with perinatal developmental stages. The preferred substrates for fetal hearts are carbohydrates, which transitions to a preference for fatty acids postnatally. The underdevelopment of lipid metabolism mechanisms in preterm infants cause imbalances or dysfunction in uptake, cellular processing, and storage of fatty acids; and increase the risks for long term cardiovascular and metabolic diseases. It is unknown whether the heart can process fatty acids before birth, and how it affects cardiomyocyte growth. The aim of this study was to determine the effects of Intralipid infusion on fetal sheep cardiac myocyte growth. We hypothesized that the size of cardiomyocytes would remain unchanged, however we expected an increase in maturity. Methods: Intralipid 20® was infused into instrumented fetal sheep (IL, 0.4 ml/kg/hr for 8 days, n=4F/7M); the contralateral twin received saline at a comparable rate (CON, n=7F/4M). Hearts were collected at 133 days gestational age (dGA; term is 147 dGA), and enzymatically dissociated, then myocytes fixed in paraformaldehyde. The length and width were measured in 100 myocytes using a wet mount, under calibrated light microscopy (40x, Zeiss Axiophot), and analyzed with Image Pro 6.3. Nucleation was determined in 500 cells; percentage binucleation is a surrogate measure of maturation. Data are presented as mean ± standard deviation. Groups were compared by t-test. Results: Body weight (IL, 4.2 ± 0.6 vs. CON, 4.1 ± 0.6kg) and heart weight (IL, 29.9 ± 4.1 vs. CON, 27.2 ± 4.6g) were not different between the lipid and control fetuses. Interim results indicate no differences in length or diameter in cardiomyocytes of the left and right ventricle (IL, N=3-7; CON, N=7-9). We found no differences in cardiomyocyte length in the septum, but Intralipid (N=10) increased the diameter of mononucleated (+12%, P=0.016) and binucleated (+11%, P=0.012) myocytes (vs. CON, N=7). In the septum, Intralipid treatment increased binucleation (P&lt;0.02; 69.2 ± 8.0% vs 60.8 ± 9.7%). In the RV, increased binucleation was only a tendency (P&lt;0.06; 70.7 ± 6.4% vs 60.8 ± 9.9%; IL n=6). Binucleation was unaffected in the LV (67.1 ± 9.9%). Summary/Conclusion: The increase in diameter of fetal cardiomyocytes in the septum could reflect different regional regulation of growth to the infused intralipid. Interestingly, parallels could be made between the septal hypertrophy described in offspring from diabetic mothers. This study is funded by NIH R01HL146997 and R01HL142483. KI is funded by a NIH supplement to R01HL142483. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.