Pathogenesis Of Cardiac Diseases Research Articles

Role of epicardial adipose tissue in diabetic cardiomyopathy through the lens of cardiovascular magnetic resonance imaging - a narrative review.

Accumulating evidence suggests that ectopic/visceral adiposity may play a key role in the pathogenesis of nonischaemic cardiovascular diseases associated with type 2 diabetes. Epicardial adipose tissue (EAT) is a complex visceral fat depot, covering 80% of the cardiac surface with anatomical and functional contiguity to the myocardium and coronary arteries. EAT interacts with the biology of the underlying myocardium by secreting a wide range of adipokines. Magnetic resonance imaging (MRI) is the reference modality for structural and functional imaging of the heart. The technique is now also emerging as the reference imaging modality for EAT quantification. With this narrative review, we (a) surveyed contemporary clinical studies that utilized cardiovascular MRI to characterize EAT (studies published 2010-2023); (b) listed the clinical trials monitoring the response to treatment in EAT size as well as myocardial functional and structural parameters and (c) discussed the potential pathophysiological role of EAT in the development of diabetic cardiomyopathy. We concluded that increased EAT quantity and its inflammatory phenotype correlate with early signs of left ventricle dysfunction and may have a role in the pathogenesis of cardiac disease in diabetes with and without coronary artery disease.

Speckle-Tracking Strain Analysis for Mapping Spatiotemporal Contractility of Induced Pluripotent Stem Cell (iPSC)-Derived Cardiomyocytes.

Human induced pluripotent stem cell (hiPSC)-derived cardiomyocytes (hiPSC-CMs) hold tremendous potential for cardiovascular disease modeling, drug screening, personalized medicine, and pathophysiology studies. The availability of a robust protocol and functional assay for studying phenotypic behavior of hiPSC-CMs is essential for establishing an in vitro disease model. Many heart diseases manifest due to changes in the mechanical strain of cardiac tissue. Therefore, non-invasive evaluation of the contractility properties of hiPSC-CMs remains crucial to gain an insight into the pathogenesis of cardiac diseases. Speckle tracking-based strain analysis is an efficient non-invasive method that uses video microscopy and image analysis of beating hiPSC-CMs for quantitative evaluation of mechanical contractility properties. This article presents step-by-step protocols for extracting quantitative contractility properties of an hiPSC-CM system obtained from five members of a family, of whom three were affected by DiGeorge syndrome, using speckle tracking-based strain analysis. The hiPSCs from the family members were differentiated and purified into hiPSC-CMs using metabolic selection. Time-lapse images of hiPSC-CMs were acquired using high-spatial-resolution and high-time-resolution phase-contrast video microscopy. Speckled images were characterized by evaluating the cross-correlation coefficient, speckle size, speckle contrast, and speckle quality of the images. The optimum parameters of the speckle tracking algorithm were determined by performing sensitivity analysis concerning computation time, effective mapping area, average contraction velocity, and strain. Furthermore, the hiPSC-CM response to adrenaline was evaluated to validate the sensitivity of the strain analysis algorithm. Then, we applied speckle tracking-based strain analysis to characterize the dynamic behavior of patient-specific hiPSC-CMs from the family members affected/unaffected by DiGeorge syndrome. Here, we report an efficient and manipulation-free method to analyze the contraction displacement vector and velocity field, contraction-relaxation strain rate, and contractile cycles. Implementation of this method allows for quantitative analysis of the contractile phenotype characteristics of hiPSC-CMs to distinguish possible cardiac manifestation of DiGeorge syndrome. © 2023 Wiley Periodicals LLC. Basic Protocol 1: Differentiation of iPSCs into iPSC-derived cardiomyocytes (iPSC-CMs) and metabolic selection of differentiated iPSC-CMs Support Protocol 1: Culture, maintenance, and expansion of human iPSCs Support Protocol 2: Immunohistochemistry of iPSC-CMs Basic Protocol 2: Time-lapse speckle imaging of iPSC-CMs and speckle quality characterization Support Protocol 3: Enhancement of local contrast of videos by applying contrast limited adaptive histogram equalization (CLAHE) to all frames Support Protocol 4: Evaluation of average speckle size Support Protocol 5: Evaluation of average speckle contrast Support Protocol 6: Determination of relative peak height, Pc(x), of consecutive images acquired from video microscopy of iPSC-CMs Basic Protocol 3: Speckle tracking-based analysis of beating iPSC-CMs Support Protocol 7: Validation of sensitivity of the speckle tracking analysis for mapping the contractility of iPSC-CMs Basic Protocol 4: Data extraction, visualization, and mapping of contractile cycles of iPSC-CMs.

Platelets reprogram monocyte functions by secreting MMP-9 to benefit postoperative outcomes following acute aortic dissection

Platelets have a great ability to modulate immune responses. Monocyte-platelet aggregates (MPAs) are associated with the pathogenesis of cardiac disease. Notably, a low preoperative platelet count often indicates poor postoperative recovery following acute aortic dissection (AAD). The functions of platelets and MPAs in AAD, however, remain poorly understood. We found that, despite decreased platelet counts, platelets were also activated in AAD patients, with significant alterations in immune-modulating mediators. Of interest, monocytes in AAD patients had a suppressed immune status, which was correlated with poor outcomes following surgery. Interestingly, platelets preferentially aggregated with monocytes, and the levels of MPAs were related to recovery after surgical repair in AAD patients. Platelets restored suppressed monocyte functions in AAD patients by forming aggregates and partly by secreting matrix metalloproteinase-9 (MMP-9). Thus, the results point to a previously unknown mechanism for platelets involving monocyte reprogramming, which may improve postoperative outcomes following complex cardiovascular surgery.

MicroRNA-146: Biomarker and Mediator of Cardiovascular Disease

Cardiovascular diseases (CVDs) are the prime cause of morbidity and mortality worldwide. Although noticeable progress has been made in the diagnosis, prognosis, and treatment, there is still a critical demand for new diagnostic biomarkers and novel therapeutic interventions to reduce this disease incidence. Many investigations have been conducted on the regulatory effects of microRNAs in cardiovascular diseases. miRNA circulating serum level changes are correlated with several CVDs. In addition, there is growing evidence representing the potential role of miRNAs as diagnostic biomarkers or potential therapeutic targets for CVD. Preliminary studies identified the prominent role of miR-146 in host defense, innate immunity, and different immunological diseases by regulating cytokine production and innate immunity modification in bacterial infections. However, more recently, it was also associated with CVD development. miR-146 has received much attention, with positive results in most studies. Research demonstrated the crucial role of this molecule in the pathogenesis of cardiac disease and related mechanisms. As a result, many potential applications of miR-146 are expected. In this paper, we provide an overview of recent studies highlighting the role of miR-146 in CVD, focusing on CAD (coronary artery disease), cardiomyopathy, and MI (myocardial infarction) in particular and discussing its current scientific state, and use a prognostic biomarker as a therapeutic agent for cardiovascular diseases.

Fibroblast GSK-3α Promotes Fibrosis via RAF-MEK-ERK Pathway in the Injured Heart.

Heart failure is the leading cause of mortality, morbidity, and health care expenditures worldwide. Numerous studies have implicated GSK-3 (glycogen synthase kinase-3) as a promising therapeutic target for cardiovascular diseases. GSK-3 isoforms seem to play overlapping, unique and even opposing functions in the heart. Previously, we have shown that of the 2 isoforms of GSK-3, cardiac fibroblast GSK-3β acts as a negative regulator of myocardial fibrosis in the ischemic heart. However, the role of cardiac fibroblast-GSK-3α in the pathogenesis of cardiac diseases is completely unknown. To define the role of cardiac fibroblast-GSK-3α in myocardial fibrosis and heart failure, GSK-3α was deleted from fibroblasts or myofibroblasts with tamoxifen-inducible Tcf21- or Postn-promoter-driven Cre recombinase. Control and GSK-3α KO mice were subjected to cardiac injury and heart parameters were evaluated. The fibroblast kinome mapping was carried out to delineate molecular mechanism followed by in vivo and in vitro analysis. Fibroblast-specific GSK-3α deletion restricted fibrotic remodeling and preserved function of the injured heart. We observed reductions in cell migration, collagen gel contraction, α-SMA protein levels, and expression of ECM genes in TGFβ1-treated KO fibroblasts, indicating that GSK-3α is required for myofibroblast transformation. Surprisingly, GSK-3α deletion did not affect SMAD3 activation, suggesting the profibrotic role of GSK-3α is SMAD3 independent. The molecular studies confirmed decreased ERK signaling in GSK-3α-KO CFs. Conversely, adenovirus-mediated expression of a constitutively active form of GSK-3α (Ad-GSK-3αS21A) in fibroblasts increased ERK activation and expression of fibrogenic proteins. Importantly, this effect was abolished by ERK inhibition. GSK-3α-mediated MEK-ERK activation is a critical profibrotic signaling circuit in the injured heart, which operates independently of the canonical TGF-β1-SMAD3 pathway. Therefore, strategies to inhibit the GSK-3α-MEK-ERK signaling circuit could prevent adverse fibrosis in diseased hearts.

Chemerin-9 stimulates migration in rat cardiac fibroblasts in vitro

Since chemerin is an adipocytokine whose concentration in blood increases in the subjects with various cardiac diseases, chemerin may be involved in pathogenesis of cardiac diseases. In the present study, we examined the effects of chemerin-9, an active fragment of chemerin, on functions of cardiac fibroblasts, which are involved in pathophysiology of cardiac diseases. Primary cardiac fibroblasts were enzymatically isolated from adult male Wistar rats. Migration of cardiac fibroblasts was measured by a Boyden chamber assay and a scratch assay. Phosphorylation of Akt and extracellular signal-regulated kinase (ERK) was measured by Western blotting. Reactive oxygen species (ROS) production was measured by 2′,7′-dichlorodihydrofluoresein staining. Chemerin-9 significantly stimulated migration in cardiac fibroblasts. Chemerin-9 significantly stimulated phosphorylation of Akt and ERK as well as ROS production. An Akt pathway inhibitor, LY294002, an ERK pathway inhibitor, PD98059, an antagonist of chemokine-like receptor 1 (CMKLR1), 2-(α-Napththoyl) ethyltrimethylammonium iodide, or an antioxidant, N-acetyl-L-cysteine prevented the migration induced by chemerin-9. In summary, we for the first time revealed that chemerin-9 stimulates migration perhaps through the ROS-dependent activation of Akt and ERK via CMKLR1 in cardiac fibroblasts. It is proposed that chemerin plays a role in the pathogenesis of cardiac diseases.

MicroRNA let-7a, -7e and -133a attenuate hypoxia-induced atrial fibrosis via targeting collagen expression and the JNK pathway in HL1 cardiomyocytes

Abstract Background Atrial fibrillation (AF) is becoming an enormous public health challenge, and it is associated with major cardiovascular morbidity and mortality. There is a need for a better understanding of the causes and consequences of the hypoxia-related development of AF and atrial remodeling. Fibrosis is a hallmark of atrial structural remodeling. Micro-ribonucleic acids (miRNAs) have been reported to have an impact on the pathogenesis of cardiac diseases. Evidence that specific miRNAs can influence AF related to atrial structural remodeling and fibrosis via the modulation of collagens under myocardial hypoxic conditions is lacking. The aim of this study was to investigate the role of miRNAs in the modulation of fibrotic molecular mechanisms in response to hypoxic conditions, which may mediate atrial fibrosis. Methods Hypoxia was induced by cobalt chloride and hypoxia chamber respectively. MiRNA arrays were used to identify the specific miRNAs associated with the modulation of fibrotic genes. Luciferase assay, real-time polymerase chain reaction, immunofluorescence and Western blotting were used to investigate the effects of miRNAs on the expressions of the fibrotic markers collagen I and III (COL1A, COL3A) and phosphorylation levels of the stress kinase c-Jun N-terminal kinase (JNK) pathway in cultured HL-1 atrial cardiomyocytes cell line. Results COL1A and COL3A were found to be the direct regulatory targets of miR-let-7a, miR-let-7e and miR-133a in hypoxic atrial cardiac cells in vitro. The expressions of COL1A and COL3A were influenced by treatment with miRNA mimic and antagomir. The delivery of miR-133a, miR-let-7a or miR-let-7e inhibited hypoxia-induced collagen expression. The JNK pathway was critical in the pathogenesis of atrial fibrosis. Inhibition of JNK phosphorylation (JNK inhibitor SP600125) could be able to increase expression of miRNAs and repressed the fibrotic markers COL1A and COL3A which in turn might reduce the arrhythmogenic atrial remodeling. This study highlights the important role of miRNA in hypoxia-related atrial remodeling as well as atrial fibrosis. Conclusion MiRNA let-7a, miR-let-7e and miR-133a play important roles in hypoxia-related atrial fibrosis by inhibiting collagen expression and post-transcriptional repression by the JNK pathway. These novel findings may lead to the development of new therapeutic strategies. Funding Acknowledgement Type of funding sources: Public grant(s) – National budget only. Main funding source(s): This work was supported by the grants from the Ministry of Science and Technology (MOST), Taiwan, ROC Regulation of cardiac fibrosisRegulation of collagen types by miRNAs

Abstract P317: Cardiac Fibroblast GSK3α Promotes Myocardial Fibrotic Remodeling Through GSK3α-ERK-IL11 Signaling Circuit

Background: Myocardial fibrosis contributes significantly to heart failure (HF). Fibroblasts are among the predominant cell type in the heart and are primary drivers of fibrosis. To identify the kinases involved in fibrosis, we analyzed the kinome of mouse cardiac fibroblasts (CF) isolated from normal and failing hearts. This unbiased screening revealed the critical role of the GSK-3 family-centric pathways in fibrosis. Previously we have shown that among two isoforms of GSK3, CF-GSK3β acts as a negative regulator of fibrosis in the injured heart. However, the role of CF-GSK3α in the pathogenesis of cardiac diseases is completely unknown. Methods and Results: To define the role of CF-GSK3α in HF, we employed two novel fibroblast-specific KO mouse models. Specifically, GSK3α was deleted from fibroblasts or myofibroblasts with tamoxifen-inducible Tcf21- or periostin- promoter-driven Cre recombinase. In both models, GSK3α deletion restricted pressure overload-induced cardiac fibrosis and preserved cardiac function. We examined the effect of GSK3α deletion on myofibroblast transformation and pro-fibrotic TGFβ1-SMAD3 signaling in vitro . A significant reduction in cell migration, collagen gel contraction, and α-SMA expression in TGFβ1-treated KO CFs confirmed that GSK3α is required for myofibroblast transformation. Surprisingly, GSK3α deletion did not affect SMAD3 activation, indicating the pro-fibrotic role of GSK3α is SMAD3 independent. To further delineate the underlying mechanisms, proteins were isolated from CFs of WT and KO mice at 4 weeks post-injury, and kinome profiling was performed. The kinome analysis identified the downregulation of RAF family kinase activity in KO CFs. Moreover, mapping of significantly altered kinases against literature annotated interactions generated ERK-centric networks. Consistently, flow cytometric analysis of CFs confirmed significantly low levels of pERK in KO mice. Additionally, our in vitro studies demonstrated that GSK3α deletion prevents TGFβ1-induced ERK activation. Interestingly, IL-11, a pro-fibrotic downstream effector of TGFβ1, was remarkably reduced in KO CFs and ERK inhibition further decreased IL-11 expression. Taken together, herein, we discovered the GSK3α-ERK-IL-11 signaling as a critical pro-fibrotic pathway in the heart. Strategies to inhibit this pro-fibrotic network could prevent adverse fibrosis and HF. Conclusion: CF-GSK3α plays a causal role in myocardial fibrosis that could be therapeutically targeted for future clinical applications.

Impact of obesity on day-night differences in cardiac metabolism.

An intrinsic property of the heart is an ability to rapidly and coordinately adjust flux through metabolic pathways in response to physiologic stimuli (termed metabolic flexibility). Cardiac metabolism also fluctuates across the 24‐hours day, in association with diurnal sleep‐wake and fasting‐feeding cycles. Although loss of metabolic flexibility has been proposed to play a causal role in the pathogenesis of cardiac disease, it is currently unknown whether day‐night variations in cardiac metabolism are altered during disease states. Here, we tested the hypothesis that diet‐induced obesity disrupts cardiac “diurnal metabolic flexibility”, which is normalized by time‐of‐day‐restricted feeding. Chronic high fat feeding (20‐wk)‐induced obesity in mice, abolished diurnal rhythms in whole body metabolic flexibility, and increased markers of adverse cardiac remodeling (hypertrophy, fibrosis, and steatosis). RNAseq analysis revealed that 24‐hours rhythms in the cardiac transcriptome were dramatically altered during obesity; only 22% of rhythmic transcripts in control hearts were unaffected by obesity. However, day‐night differences in cardiac substrate oxidation were essentially identical in control and high fat fed mice. In contrast, day‐night differences in both cardiac triglyceride synthesis and lipidome were abolished during obesity. Next, a subset of obese mice (induced by 18‐wks ad libitum high fat feeding) were allowed access to the high fat diet only during the 12‐hours dark (active) phase, for a 2‐wk period. Dark phase restricted feeding partially restored whole body metabolic flexibility, as well as day‐night differences in cardiac triglyceride synthesis and lipidome. Moreover, this intervention partially reversed adverse cardiac remodeling in obese mice. Collectively, these studies reveal diurnal metabolic inflexibility of the heart during obesity specifically for nonoxidative lipid metabolism (but not for substrate oxidation), and that restricting food intake to the active period partially reverses obesity‐induced cardiac lipid metabolism abnormalities and adverse remodeling of the heart.

Growth differentiation factor 11 mitigates cardiac radiotoxicity via activating AMPKα

Cardiac radiotoxicity largely impedes the therapeutic benefits of radiotherapy to malignancies. Growth differentiation factor 11 (GDF11) is implicated in the pathogenesis of cardiac diseases under different pathological conditions. This study aims to investigate the role and underlying mechanisms of GDF11 on cardiac radiotoxicity. Mice were injected with cardiotropic adeno-associated virus 9 carrying the full-length mouse GDF11 gene or negative control under a cTnT promoter from the tail vein, and then received a single dose of 20 Gray (Gy) whole-heart irradiation (WHI) for 16 weeks to imitate cardiac radiotoxicity. Compound C (CC, 20 mg/kg) was intraperitoneally injected every two days at 1 week before WHI stimulation to inhibit 5′ AMP-activated protein kinase α (AMPKα). Cardiac GDF11 expression was significantly suppressed at both the protein and mRNA levels. GDF11 overexpression decreased oxidative stress, apoptosis, and fibrosis in radiated hearts, thereby mitigating cardiac radiotoxicity, and dysfunction. Further detection revealed that GDF11 activated AMPKα to reduce radiation-induced oxidative damage and that AMPKα inhibition by CC offset the cardioprotective effects by GDF11. GDF11 mitigates cardiac radiotoxicity via activating AMPKα and it is a promising candidate to treat cardiac radiotoxicity.

Therapeutic effects of histone deacetylase inhibitors on heart disease.

A wide range of histone deacetylase (HDAC) inhibitors have been studied for their therapeutic potential because the excessive activity and expression of HDACs have been implicated in the pathogenesis of cardiac diseases. An increasing number of preclinical studies have demonstrated the cardioprotective effects of numerous HDAC inhibitors, suggesting a wide variety of mechanisms by which the inhibitors protect against cardiac stress, such as the suppression of cardiac fibrosis and fetal gene expression, enhancement of angiogenesis and mitochondrial biogenesis, prevention of electrical remodeling, and regulation of apoptosis, autophagy, and cell cycle arrest. For the development of isoform-selective HDAC inhibitors with high efficacy and low toxicity, it is important to identify and understand the mechanisms responsible for the effects of the inhibitors. This review highlights the preclinical effects of HDAC inhibitors that act against Zn2+-dependent HDACs and the underlying mechanisms of their protective effects against cardiac hypertrophy, hypertension, myocardial infarction, heart failure, and atrial fibrillation.

The Physiological and Pathological Roles of Mitochondrial Calcium Uptake in Heart.

Calcium ion (Ca2+) plays a critical role in the cardiac mitochondria function. Ca2+ entering the mitochondria is necessary for ATP production and the contractile activity of cardiomyocytes. However, excessive Ca2+ in the mitochondria results in mitochondrial dysfunction and cell death. Mitochondria maintain Ca2+ homeostasis in normal cardiomyocytes through a comprehensive regulatory mechanism by controlling the uptake and release of Ca2+ in response to the cellular demand. Understanding the mechanism of modulating mitochondrial Ca2+ homeostasis in the cardiomyocyte could bring new insights into the pathogenesis of cardiac disease and help developing the strategy to prevent the heart from damage at an early stage. In this review, we summarized the latest findings in the studies on the cardiac mitochondrial Ca2+ homeostasis, focusing on the regulation of mitochondrial calcium uptake, which acts as a double-edged sword in the cardiac function. Specifically, we discussed the dual roles of mitochondrial Ca2+ in mitochondrial activity and the impact on cardiac function, the molecular basis and regulatory mechanisms, and the potential future research interest.

Role of resistin, IL-6 and NH2-terminal portion proBNP in the pathogenesis of cardiac disease in type 2 diabetes mellitus.

IntroductionEpidemiological and genetic studies have recorded the association between proinflammatory cytokines and the development of insulin resistance, diabetes, and cardiovascular disease. The role of interleukin 6 (IL-6), NH2-terminal portion pro-brain natriuretic peptide (NT-proBNP) and resistin in the pathogenesis of heart disease in type 2 diabetes mellitus (T2DM) is still a matter of controversy. The current study aimed to evaluate the role of these biomarkers in the development of left ventricular systolic dysfunction and the ability to use them as non-invasive test in the prediction of left ventricular hypertrophy and systolic dysfunction in T2DM.Research design and methods150 participants were included in this case–control study. Patients were divided into two subgroups according to echocardiographic findings: group 1a included 46 patients with type 2 diabetes mellitus and echocardiographic evidence of abnormal systolic function; group 1b included 54 patients with type 2 diabetes mellitus and with normal echocardiogenic study; and group 2 included 50 apparently healthy controls. Routine laboratory investigations such as complete blood count, liver and renal function tests, and lipid profile, serum IL-6, NT-proBNP, and resistin were measured in all participants. Conventional echocardiography was done with special concern on the assessment of left ventricular systolic function (ejection fraction).ResultsThere was a significant increase in the level of resistin, NT-proBNP and IL-6 in group 1a patients compared with group 1b and in healthy controls. Echocardiographic parameters showed a significant increase in left ventricular mass index, left ventricle posterior wall thickness, interventricular septum thickness, and left ventricle mass in group 1a compared with group 1b and the control group. The increased left ventricular mass index was associated with higher levels of IL-6, NT-proBNP and resistin.ConclusionsProinflammatory cytokines had a clear relation with left ventricular systolic dysfunction and hypertrophy and can be used as early non-invasive markers for detection of left ventricular remodeling and systolic dysfunction in patients with T2DM.

MiRNA-181a is a novel regulator of aldosterone-mineralocorticoid receptor-mediated cardiac remodelling.

The aldosterone-mineralocorticoid receptor (Aldo-MR) pathway is activated during cardiac stress, such as hypertension, myocardial infarction (MI), and heart failure. The importance of Aldo and MR in the pathogenesis of cardiac diseases is well established; however, the regulatory mechanisms behind Aldo/MR-induced cardiac remodelling remain uncertain. We here investigated potential miRNA-mediated regulation of the Aldo-MR pathway to improve mechanistic understanding. High-throughput screening of 2,555 miRNAs using an MR responsive stable cardiomyocyte cell line (MMTV-GFP-HL-1) identified miR-181a as a potential regulator of Aldo-MR pathway. MiR-181a was found to downregulate the expression of Ngal (lipocalin-2), a well-established downstream effector molecule of Aldo-MR. In addition, Aldo-induced cellular hypertrophy decreased significantly upon miR-181a overexpression. Genetic miR-181 knockout in murine MI model led to deteriorated cardiac function, cardiac remodelling, and activation of Aldo-MR pathway while AAV9-mediated miR-181a overexpression improved cardiac function and deactivated Aldo-MR pathway proving a cardio-protective role of miR-181a. Global RNA sequencing of cells under Aldo treatment with/without miR-181a overexpression identified potential miR-181a targets functionally contributing to Aldo-MR pathway. Adamts1, a direct target of miR-181a, was found to be downregulated with miR-181a overexpression and upregulated with inhibition. Similar to miR-181a overexpression, siRNA-mediated inhibition of Adamts1 inhibited Aldo-MR pathway. We here show that miR-181a is a novel regulator of the Aldo-MR pathway regulating the levels of Ngal via direct targeting of Adamts1. This new insight establishes miR-181a as a factor of immense value participating in downstream networks of Aldo-MR pathway. Our in vivo studies further confirmed miR-181a as cardio-protective under MI stress. Thus, miR-181a's involvement in Aldo-MR-mediated cardiac remodelling confers it with tremendous potential to be developed further as a new therapeutic target.

Meet the First Author.

Meet the First Author.

Baicalein protects cardiomyocytes from oxidative stress induced programmed necrosis by stabilizing carboxyl terminus of Hsc70-interacting protein

Cardiomyocyte necrosis has been reported to be a major component in pathogenesis of cardiac diseases. We noticed that baicalein, a kind of principal components in the roots of Scutellaria baicalensis Georgi, exerts cardioprotective effects by inhibiting oxidative stress and apoptosis of Cardiomyocytes. However, it is rarely reported whether baicalein exerts myocardial protection by inhibiting necrosis. In addition, the death receptor-dependent necrotic cell death is mediated by receptor interacting serine/threonine kinase 1/3(RIPK1/RIPK3). Thus, targeting RIPK1/RIPK3 may represent potential preventive and therapeutic opportunities of necrosis-related cardiac diseases. Carboxyl terminus of Hsc70-interacting protein (CHIP) has been reported to play a significant role on cardiac protection through its E3 ubiquitin ligase activity, but it is not clear whether CHIP regulates RIP1K/RIPK3 in cardiomyocytes necrosis. In our study, we firstly found that baicalein attenuated myocardial necrosis in vitro and in vivo, and it significantly suppressed myocardial necrosis induced by oxidative stress through disturbing RIPK1/RIPK3 necrososme formation in vitro. Besides, we verified that CHIP suppressed myocardial necrosis through ubiquitylation-dependent degradation of RIPK3. And then we firstly speculated that baicalein may promote stability of CHIP to exert cardioprotective effects, and we also found that baicalein promoted the E3 ubiquitin ligase activity of CHIP to negatively regulate RIPK3. Taken together, our results for the first time reveal a pivotal role of baicalein in stabilizing CHIP activity to promote RIPK1/RIPK3 ubiquination and degradation in order to attenuate Cardiomyocyte necrosis.

The Role of Resistin, IL-6 and NH2-Terminal Portion ProBNP in Pathogenesis of Cardiac Disease in Type 2 Diabetes Mellitus

Background: The role of interleukin-6 (IL-6), Nt-pro BNP and resistin in the pathogenesis of heart disease in type 2 diabetic is still a matter of controversy. The current study aimed to declare the association between circulating levels of resistin, Nt-pro BNP and IL-6 and cardiac dysfunction in type 2 diabetes (T2DM) and to evaluate them as non invasive markers of Echocardiogenic changes. Methods: 150 participants shared in this study, 100 patients with T2DM and 50 healthy controls. According to echocardiographic findings, the patients were subdivided into 2 subgroups: Group 1a, includes 46 patients with T2DM and evidence of cardiac remolding and systolic dysfunction, and 54 patients were without Echocardiogenic changes as group 1b. Routine laboratory investigations were performed such as complete blood count, liver and renal function tests and lipid profile. Echocardiography was done to assess cardiac systolic function. Serum IL- 6, Nt-pro BNP and resistin were measured for all participants. Results: There was a significant increase in the levels of resistin, Nt-pro BNP and IL-6 in group 1a patients compared to 1b group and healthy controls. Echocardiograpgic parameters showed a significant increase of left ventricular mass index (LVMI), left ventricle posterior wall thickness (LVPW), inter-ventricular septum (IVS), left ventricle mass (LVM) in group 1a compared to group 1b and control group. The increased LVMI was associated with higher levels of IL-6, Nt-pro BNP and resistin. Conclusions: Pro-inflammatory cytokines play an important role in the diabetogensis and cardiac outcome in T2DM. They could be used as early non-invasive markers for cardiac remolding and systolic dysfunction in T2DM patients. Large scale future studies could be done to investigate the role of genetic polymorphism of these cytokines in development of cardiac stroke in DM. Funding Statement: The authors stated that they did not receive any funding. Declaration of Interests: The authors declare that there is no conflict of interest regarding the publication of this paper. Ethics Approval Statement: An informed written consent was obtained from all individual participants included in the study. The study was reviewed and approved by the ethical committee at the National Liver Institute.

Comprehensive autophagy evaluation in cardiac disease models.

Autophagy is a highly conserved recycling mechanism essential for maintaining cellular homeostasis. The pathophysiological role of autophagy has been explored since its discovery 50 years ago, but interest in autophagy has grown exponentially over the last years. Many researchers around the globe have found that autophagy is a critical pathway involved in the pathogenesis of cardiac diseases. Several groups have created novel and powerful tools for gaining deeper insights into the role of autophagy in the aetiology and development of pathologies affecting the heart. Here, we discuss how established and emerging methods to study autophagy can be used to unravel the precise function of this central recycling mechanism in the cardiac system.

Abstract 351: Suppression of Store Operated Ca 2+ Entry Components, dStim and dOrai, Results in Dilated Cardiomyopathy

Cardiac disease is a leading cause of morbidity and mortality throughout the western world with current treatment options limited to palliative pharmacological or invasive therapy. The discovery of curative treatments will rely on thorough understanding of the molecular mechanisms that govern cardiac patho-physiology. Significantly, irregularities in calcium (Ca 2+ ) homeostasis are a major contributing factor to the pathogenesis of cardiac diseases, and targeting Ca 2+ signaling mechanisms may therefore be an important approach to novel therapeutic development. Our lab has recently identified a requirement for the store operated Ca 2+ entry (SOCE) pathway, whereby Ca 2+ enters the cell in response to endo/sarcoplasmic reticulum (ER/SR) store depletion, in Drosophila cardiac physiology. Heart-specific suppression of key SOCE pathway components, Stim and Orai, induced dilated cardiomyopathy characterized by enlarged end-diastolic and end-systolic diameters and decreased fractional shortening. Animals with SOCE suppression had a significant delay in development and ultimately died considerably earlier than controls, suggesting pathological impairment of cardiac function. Additionally, Stim and Orai suppressed hearts exhibited highly disorganized or disrupted myofibrils, suggesting either defective heart development, tissue remodeling, or degeneration resulting from disrupted Ca 2+ homeostasis. We are currently testing these possibilities by restricting Stim and Orai suppression to specific lifecycle stages, and we are analyzing Ca 2+ transients in intact hearts to determine whether SOCE is required for contractile Ca 2+ cycling or may have a contraction-independent signaling role. Collectively, our results demonstrate an essential role for SOCE in normal cardiac physiology, and present how powerful genetic tools and in vivo analyses in Drosophila will allow us to define the mechanistic basis for this requirement.

Research progress on the role of microRNAs of microRNA-15 family in cardiac diseases

The microRNA-15 (miR-15) family consists of six miRNAs which share the same seed sequence, and participates in diverse biological processes, including cell apoptosis, differentiation, proliferation, cell cycle and carcinogenesis. Recently, many researches have indicated the important role that aberrantly regulated miR-15 family members play in the pathogenesis of cardiac diseases. The present review is intended to elucidate the changes in the expression of miR-15 family members in various cardiac diseases, discuss the potential clinical values, and summary their effects on the pathogenesis of the diseases. MiR-15 family is closely associated with cardiac diseases and therapies targeting on the family will facilitate the treatment of the diseases in the future. Key words: MicroRNA; MicroRNA-15; Cardiac disease