T-bet deficiency attenuates cardiac remodelling in rats

Vascular endothelial cell injury: causes, molecular mechanisms, and treatments

Vascular endothelial cells form a single layer of flat cells that line the inner surface of blood vessels, extending from large vessels to the microvasculature of various organs. These cells are crucial metabolic and endocrine components of the body, playing vital roles in maintaining circulatory stability, regulating vascular tone, and preventing coagulation and thrombosis. Endothelial cell injury is regarded as a pivotal initiating factor in the pathogenesis of various diseases, triggered by multiple factors, including infection, inflammation, and hemodynamic changes, which significantly compromise vascular integrity and function. This review examines the causes, underlying molecular mechanisms, and potential therapeutic approaches for endothelial cell injury, focusing specifically on endothelial damage in cardiac ischemia/reperfusion (I/R) injury, sepsis, and diabetes. It delves into the intricate signaling pathways involved in endothelial cell injury, emphasizing the roles of oxidative stress, mitochondrial dysfunction, inflammatory mediators, and barrier damage. Current treatment strategies-ranging from pharmacological interventions to regenerative approaches and lifestyle modifications-face ongoing challenges and limitations. Overall, this review highlights the importance of understanding endothelial cell injury within the context of various diseases and the necessity for innovative therapeutic methods to improve patient outcomes.

IRX2 regulates angiotensin II-induced cardiac fibrosis by transcriptionally activating EGR1 in male mice

Cardiac fibrosis is a common feature of chronic heart failure. Iroquois homeobox (IRX) family of transcription factors plays important roles in heart development; however, the role of IRX2 in cardiac fibrosis has not been clarified. Here we report that IRX2 expression is significantly upregulated in the fibrotic hearts. Increased IRX2 expression is mainly derived from cardiac fibroblast (CF) during the angiotensin II (Ang II)-induced fibrotic response. Using two CF-specific Irx2-knockout mouse models, we show that deletion of Irx2 in CFs protect against pathological fibrotic remodelling and improve cardiac function in male mice. In contrast, Irx2 gain of function in CFs exaggerate fibrotic remodelling. Mechanistically, we find that IRX2 directly binds to the promoter of the early growth response factor 1 (EGR1) and subsequently initiates the transcription of several fibrosis-related genes. Our study provides evidence that IRX2 regulates the EGR1 pathway upon Ang II stimulation and drives cardiac fibrosis.

Tisp40 prevents cardiac ischemia/reperfusion injury through the hexosamine biosynthetic pathway in male mice

The hexosamine biosynthetic pathway (HBP) produces uridine diphosphate N-acetylglucosamine (UDP-GlcNAc) to facilitate O-linked GlcNAc (O-GlcNAc) protein modifications, and subsequently enhance cell survival under lethal stresses. Transcript induced in spermiogenesis 40 (Tisp40) is an endoplasmic reticulum membrane-resident transcription factor and plays critical roles in cell homeostasis. Here, we show that Tisp40 expression, cleavage and nuclear accumulation are increased by cardiac ischemia/reperfusion (I/R) injury. Global Tisp40 deficiency exacerbates, whereas cardiomyocyte-restricted Tisp40 overexpression ameliorates I/R-induced oxidative stress, apoptosis and acute cardiac injury, and modulates cardiac remodeling and dysfunction following long-term observations in male mice. In addition, overexpression of nuclear Tisp40 is sufficient to attenuate cardiac I/R injury in vivo and in vitro. Mechanistic studies indicate that Tisp40 directly binds to a conserved unfolded protein response element (UPRE) of the glutamine-fructose-6-phosphate transaminase 1 (GFPT1) promoter, and subsequently potentiates HBP flux and O-GlcNAc protein modifications. Moreover, we find that I/R-induced upregulation, cleavage and nuclear accumulation of Tisp40 in the heart are mediated by endoplasmic reticulum stress. Our findings identify Tisp40 as a cardiomyocyte-enriched UPR-associated transcription factor, and targeting Tisp40 may develop effective approaches to mitigate cardiac I/R injury.

Immune Cells in Cardiac Injury Repair and Remodeling

PURPOSE OF REVIEW

Immune cells are emerging as central cellular components of the heart which communicate with cardiac resident cells during homeostasis, cardiac injury, and remodeling. These findings are contributing to the development and continuous expansion of the new field of cardio-immunology. We review the most recent literature on this topic and discuss ongoing and future efforts to advance this field forward.

RECENT FINDINGS

Cell-fate mapping, strategy depleting, and reconstituting immune cells in pre-clinical models of cardiac disease, combined with the investigation of the human heart at the single cell level, are contributing immensely to our understanding of the complex intercellular communication between immune and non-immune cells in the heart. While the acute immune response is necessary to initiate inflammation and tissue repair post injury, it becomes detrimental when sustained over time and contributes to adverse cardiac remodeling and pathology. Understanding the specific functions of immune cells in the context of the cardiac environment will provide new opportunities for immunomodulation to induce or tune down inflammation as needed in heart disease.

The heart under pressure: immune cells in fibrotic remodeling

The complex syndrome of heart failure (HF) is characterized by increased left ventricular pressures. Cardiomyocytes increase in size, cardiac fibroblasts transform and make extracellular matrix, and leukocytes infiltrate the cardiac tissue and alter cardiomyocyte and cardiac fibroblast function. Here we review recent advances in our understanding of the cellular composition of the heart during homeostasis and in response to cardiac pressure overload, with an emphasis on immune cell communication with cardiac fibroblasts and its consequences in cardiac remodeling.

Irisin alleviates obesity-related spermatogenesis dysfunction via the regulation of the AMPKα signalling pathway

BACKGROUND

Infertility is a common complication in obese men. Oxidative stress and testicular apoptosis play critical roles in obesity-induced spermatogenesis dysfunction. It has been reported that irisin, an exercise-induced myokine, may attenuate oxidative damage and testicular apoptosis in several diseases; however, its role in obesity-induced spermatogenesis dysfunction remains unclear. The purpose of this study was to investigate the role and underlying mechanism of irisin in obesity-induced dysfunction of spermatogenesis.

METHODS

Male mice were fed a high-fat diet (HFD) for 24 weeks to establish a model of obesity-induced spermatogenesis dysfunction. To explore the effects of irisin, mice were subcutaneously infused with recombinant irisin for 8 weeks beginning at 16 weeks after starting a HFD. To confirm the role of AMP-activated protein kinase α (AMPKα), AMPKα-deficient mice were used.

RESULTS

The data showed decreased serum irisin levels in obese patients, which was negatively correlated with sperm count and progressive motility. Irisin was downregulated in the plasma and testes of obese mice. Supplementation with irisin protected against HFD-induced spermatogenesis dysfunction and increased testosterone levels in mice. HFD-induced oxidative stress, endoplasmic reticulum (ER) stress and testicular apoptosis were largely attenuated by irisin treatment. Mechanistically, we identified that irisin activated the AMPKα signalling pathway. With AMPKα depletion, we found that the protective effects of irisin on spermatogenesis dysfunction were abolished in vivo and in vitro.

CONCLUSIONS

In conclusion, we found that irisin alleviated obesity-related spermatogenesis dysfunction via activation of the AMPKα signalling pathway. Based on these findings, we hypothesized that irisin is a potential therapeutic agent against obesity-related spermatogenesis dysfunction.

Fibronectin type III domain-containing 5 in cardiovascular and metabolic diseases: a promising biomarker and therapeutic target

Cardiovascular and metabolic diseases are the leading causes of death and disability worldwide and impose a tremendous socioeconomic burden on individuals as well as the healthcare system. Fibronectin type III domain-containing 5 (FNDC5) is a widely distributed transmembrane glycoprotein that can be proteolytically cleaved and secreted as irisin to regulate glycolipid metabolism and cardiovascular homeostasis. In this review, we present the current knowledge on the predictive and therapeutic role of FNDC5 in a variety of cardiovascular and metabolic diseases, such as hypertension, atherosclerosis, ischemic heart disease, arrhythmia, metabolic cardiomyopathy, cardiac remodeling, heart failure, diabetes mellitus, and obesity.

Protection against Doxorubicin-Related Cardiotoxicity by Jaceosidin Involves the Sirt1 Signaling Pathway

The clinical use of doxorubicin (DOX) is largely limited by its cardiotoxicity. Previous studies have shown that jaceosidin has many biological activities. However, little is known about whether jaceosidin can attenuate DOX-related acute cardiotoxicity. Here, we investigated the therapeutic effects of jaceosidin on DOX-induced acute cardiotoxicity. Mice were intraperitoneally injected with a single dose of DOX to establish an acute cardiac injury model. To explore the protective effects, mice were orally administered jaceosidin daily for 7 days, with dosing beginning 2 days before DOX injection. The results demonstrated that jaceosidin dose-dependently reduced free radical generation, inflammation accumulation, and cell loss induced by DOX in cardiomyocytes. Further studies showed that jaceosidin treatment inhibited myocardial oxidative damage and the inflammatory response and attenuated myocardial apoptotic death, thus improving cardiac function in mice injected with DOX. The inhibitory effects of jaceosidin on DOX-related acute cardiotoxicity were mediated by activation of the sirtuin1 (Sirt1) signaling pathway. Jaceosidin lost its protective effect against DOX-related injury in Sirt1-deficient cardiomyocytes and mice. In conclusion, jaceosidin has protective potential in treating DOX-related cardiac injury through activation of the Sirt1 signaling pathway.

Inflammatory Cytokines, Immune Cells, and Organ Interactions in Heart Failure

Despite mounting evidence demonstrating the significance of inflammation in the pathophysiological mechanisms of heart failure (HF), most large clinical trials that target the inflammatory responses in HF yielded neutral or even worsening outcomes. Further in-depth understanding about the roles of inflammation in the pathogenesis of HF is eagerly needed. This review summarizes cytokines, cardiac infiltrating immune cells, and extracardiac organs that orchestrate the complex inflammatory responses in HF and highlights emerging therapeutic targets.

Osteocrin, a novel myokine, prevents diabetic cardiomyopathy via restoring proteasomal activity

Proteasomal activity is compromised in diabetic hearts that contributes to proteotoxic stresses and cardiac dysfunction. Osteocrin (OSTN) acts as a novel exercise-responsive myokine and is implicated in various cardiac diseases. Herein, we aim to investigate the role and underlying molecular basis of OSTN in diabetic cardiomyopathy (DCM). Mice received a single intravenous injection of the cardiotrophic adeno-associated virus serotype 9 to overexpress OSTN in the heart and then were exposed to intraperitoneal injections of streptozotocin (STZ, 50 mg/kg) for consecutive 5 days to generate diabetic models. Neonatal rat cardiomyocytes were isolated and stimulated with high glucose to verify the role of OSTN in vitro. OSTN expression was reduced by protein kinase B/forkhead box O1 dephosphorylation in diabetic hearts, while its overexpression significantly attenuated cardiac injury and dysfunction in mice with STZ treatment. Besides, OSTN incubation prevented, whereas OSTN silence aggravated cardiomyocyte apoptosis and injury upon hyperglycemic stimulation in vitro. Mechanistically, OSTN treatment restored protein kinase G (PKG)-dependent proteasomal function, and PKG or proteasome inhibition abrogated the protective effects of OSTN in vivo and in vitro. Furthermore, OSTN replenishment was sufficient to prevent the progression of pre-established DCM and had synergistic cardioprotection with sildenafil. OSTN protects against DCM via restoring PKG-dependent proteasomal activity and it is a promising therapeutic target to treat DCM.

Advances in Genome Editing and Application to the Generation of Genetically Modified Rat Models

The rat has been extensively used as a small animal model. Many genetically engineered rat models have emerged in the last two decades, and the advent of gene-specific nucleases has accelerated their generation in recent years. This review covers the techniques and advances used to generate genetically engineered rat lines and their application to the development of rat models more broadly, such as conditional knockouts and reporter gene strains. In addition, genome-editing techniques that remain to be explored in the rat are discussed. The review also focuses more particularly on two areas in which extensive work has been done: human genetic diseases and immune system analysis. Models are thoroughly described in these two areas and highlight the competitive advantages of rat models over available corresponding mouse versions. The objective of this review is to provide a comprehensive description of the advantages and potential of rat models for addressing specific scientific questions and to characterize the best genome-engineering tools for developing new projects.

Inhibition of miR-128-3p Attenuated Doxorubicin-Triggered Acute Cardiac Injury in Mice by the Regulation of PPAR-γ

Background

The clinical usefulness of doxorubicin (DOX), an anthracycline with antitumor activity, is limited by its cardiotoxicity. Oxidative stress and myocardial apoptosis were closely associated with DOX-induced cardiac dysfunction. It has been reported that microRNA-128-3p (miR-128-3p) was involved into the regulation of redox balance. However, the role of miR-128-3p in DOX-related cardiac injury remains not yet understood. The aim of this study was to investigate the biological effect of miR-128-3p in DOX-induced cardiotoxicity.

Methods

To induce DOX-related acute cardiac injury, mice were subjected to a single injection of DOX. Inhibition of myocardial miR-128-3p was achieved by an adeno-associated virus (AAV9) system carrying a miR-128-3p sponge.

Results

The data in our study indicated that miR-128-3p was upregulated in DOX-treated hearts and cardiomyocytes. Inhibition of miR-128-3p attenuated DOX-related cardiac injury and improved cardiac function in mice. Moreover, miR-128-3p inhibition could suppress myocardial inflammatory response, oxidative damage, and cell apoptotic death in DOX-treated mice. Further analysis showed that miR-128-3p could directly target peroxisome proliferator-activated receptor γ (PPAR-γ) and decrease PPAR-γ expression. Moreover, the protective effects provided by miR-128-3p inhibition were abolished by a PPAR-γ antagonist in vivo and in vitro.

Conclusions

miR-128-3p inhibition attenuated DOX-related acute cardiac injury via the regulation of PPAR-γ in mice.

Fibrosis after Myocardial Infarction: An Overview on Cellular Processes, Molecular Pathways, Clinical Evaluation and Prognostic Value

The ischemic injury caused by myocardial infarction activates a complex healing process wherein a powerful inflammatory response and a reparative phase follow and balance each other. An intricate network of mediators finely orchestrate a large variety of cellular subtypes throughout molecular signaling pathways that determine the intensity and duration of each phase. At the end of this process, the necrotic tissue is replaced with a fibrotic scar whose quality strictly depends on the delicate balance resulting from the interaction between multiple actors involved in fibrogenesis. An inflammatory or reparative dysregulation, both in term of excess and deficiency, may cause ventricular dysfunction and life-threatening arrhythmias that heavily affect clinical outcome. This review discusses cellular process and molecular signaling pathways that determine fibrosis and the imaging technique that can characterize the clinical impact of this process in-vivo.

Activation of Nrf2 by miR-152 Inhibits Doxorubicin-Induced Cardiotoxicity via Attenuation of Oxidative Stress, Inflammation, and Apoptosis

Doxorubicin (DOX) could trigger congestive heart failure, which largely limited the clinical use of DOX. microRNAs (miRNAs) were closely involved in the pathogenesis of DOX-induced cardiomyopathy. Here, we aimed to investigate the effect of miR-152 on DOX-induced cardiotoxicity in mice. To study this, we used an adeno-associated viral vector to overexpress miR-152 in mice 6 weeks before DOX treatment, using a dose mimicking the concentrations used in the clinics. In response to DOX injection, miR-152 was significantly decreased in murine hearts and cardiomyocytes. After DOX treatment, mice with miR-152 overexpression in the hearts developed less cardiac dysfunction, oxidative stress, inflammation, and myocardial apoptosis. Furthermore, we found that miR-152 overexpression attenuated DOX-related oxidative stress, inflammation, and cell loss in cardiomyocytes, whereas miR-152 knockdown resulted in oxidative stress, inflammation, and cell loss in cardiomyocytes. Mechanistically, this effect of miR-152 was dependent on the activation of nuclear factor (erythroid-derived 2)-like 2 (Nrf2) in response to DOX. Notably, Nrf2 deficiency blocked the protective effects of miR-152 against DOX-related cardiac injury in mice. In conclusion, miR-152 protected against DOX-induced cardiotoxicity via the activation of the Nrf2 signaling pathway. These results suggest that miR-152 may be a promising therapeutic target for the treatment of DOX-induced cardiotoxicity.

Endothelial ERG alleviates cardiac fibrosis via blocking endothelin-1-dependent paracrine mechanism

Cardiac endothelium communicates closely with adjacent cardiac cells by multiple cytokines and plays critical roles in regulating fibroblasts proliferation, activation, and collagen synthesis during cardiac fibrosis. E26 transformation-specific (ETS)-related gene (ERG) belongs to the ETS transcriptional factor family and is required for endothelial cells (ECs) homeostasis and cardiac development. This study aims at investigating the potential role and molecular basis of ERG in fibrotic remodeling within the adult heart. We observed that ERG was abundant in murine hearts, especially in cardiac ECs, but decreased during cardiac fibrosis. ERG knockdown within murine hearts caused spontaneously cardiac fibrosis and dysfunction, accompanied by the activation of multiple Smad-dependent and independent pathways. However, the direct silence of ERG in cardiac fibroblasts did not affect the expression of fibrotic markers. Intriguingly, ERG knockdown in human umbilical vein endothelial cells (HUVECs) promoted the secretion of endothelin-1 (ET-1), which subsequently accelerated the proliferation, phenotypic transition, and collagen synthesis of cardiac fibroblasts in a paracrine manner. Suppressing ET-1 with either a neutralizing antibody or a receptor blocker abolished ERG knockdown-mediated deleterious effect in vivo and in vitro. This pro-fibrotic effect was also negated by RGD (Arg-Gly-Asp)-peptide magnetic nanoparticles target delivery of ET-1 small interfering RNA to ECs in mice. More importantly, we proved that endothelial ERG overexpression notably prevented pressure overload-induced cardiac fibrosis. Collectively, endothelial ERG alleviates cardiac fibrosis via blocking ET-1-dependent paracrine mechanism and it functions as a candidate for treating cardiac fibrosis. • ERG is abundant in murine hearts, especially in cardiac ECs, but decreased during fibrotic remodeling. • ERG knockdown causes spontaneously cardiac fibrosis and dysfunction. • ERG silence in HUVECs promotes the secretion of endothelin-1, which in turn activates cardiac fibroblasts in a paracrine manner. • Endothelial ERG overexpression prevents pressure overload-induced cardiac fibrosis.

Protective Effects of Oroxylin A against Doxorubicin-Induced Cardiotoxicity via the Activation of Sirt1 in Mice

Doxorubicin- (DOX-) related cardiac injury impairs the life quality of patients with cancer. This largely limited the clinical use of DOX. It is of great significance to find a novel strategy to reduce DOX-related cardiac injury. Oroxylin A (OA) has been identified to exert beneficial effects against inflammatory diseases and cancers. Here, we investigated whether OA could attenuate DOX-induced acute cardiotoxicity in mice. A single dose of DOX was used to induce acute cardiac injury in mice. To explore the protective effects, OA was administered to mice for ten days beginning from five days before DOX injection. The data in our study indicated that OA inhibited DOX-induced heart weight loss, reduction in cardiac function, and the elevation in myocardial injury markers. DOX injection resulted in increased oxidative damage, inflammation accumulation, and myocardial apoptosis in vivo and in vitro, and these pathological alterations were alleviated by treatment of OA. OA activated the sirtuin 1 (Sirt1) signaling pathway via the cAMP/protein kinase A, and its protective effects were blocked by Sirt1 deficiency. OA treatment did not affect the tumor-killing action of DOX in tumor-bearing mice. In conclusion, OA protected against DOX-related acute cardiac injury via the regulation of Sirt1.

Adding insult to injury - Inflammation at the heart of cardiac fibrosis

The fibrotic response has evolutionary worked in tandem with the inflammatory response to facilitate healing following injury or tissue destruction as a result of pathogen clearance. However, excessive inflammation and fibrosis are key pathological drivers of organ tissue damage. Moreover, fibrosis can occur in several conditions associated with chronic inflammation that are not directly caused by overt tissue injury or infection. In the heart, in particular, fibrotic adverse cardiac remodeling is a key pathological driver of cardiac dysfunction in heart failure. Cardiac fibroblast activation and immune cell activation are two mechanistic domains necessary for fibrotic remodeling in the heart, and, independently, their contributions to cardiac fibrosis and cardiac inflammation have been studied and reviewed thoroughly. The interdependence of these two processes, and how their cellular components modulate each other's actions in response to different cardiac insults, is only recently emerging. Here, we review recent literature in cardiac fibrosis and inflammation and discuss the mechanisms involved in the fibrosis-inflammation axis in the context of specific cardiac stresses, such as myocardial ischemia, and in nonischemic heart conditions. We discuss how the search for anti-inflammatory and anti-fibrotic therapies, so far unsuccessful to date, needs to be based on our understanding of the interdependence of immune cell and fibroblast activities. We highlight that in addition to the extensively reviewed role of immune cells modulating fibroblast function, cardiac fibroblasts are central participants in inflammation that may acquire immune like cell functions. Lastly, we review the gut-heart axis as an example of a novel perspective that may contribute to our understanding of how immune and fibrotic modulation may be indirectly modulated as a potential area for therapeutic research.

MicroRNA-31-5p Exacerbates Lipopolysaccharide-Induced Acute Lung Injury via Inactivating Cab39/AMPKα Pathway

Acute lung injury (ALI) and the subsequent acute respiratory distress syndrome remain devastating diseases with high mortality rates and poor prognoses among patients in intensive care units. The present study is aimed at investigating the role and underlying mechanisms of microRNA-31-5p (miR-31-5p) on lipopolysaccharide- (LPS-) induced ALI. Mice were pretreated with miR-31-5p agomir, antagomir, and their negative controls at indicated doses for 3 consecutive days, and then they received a single intratracheal injection of LPS (5 mg/kg) for 12 h to induce ALI. MH-S murine alveolar macrophage cell lines were cultured to further verify the role of miR-31-5p in vitro. For AMP-activated protein kinase α (AMPKα) and calcium-binding protein 39 (Cab39) inhibition, compound C or lentiviral vectors were used in vivo and in vitro. We observed an upregulation of miR-31-5p in lung tissue upon LPS injection. miR-31-5p antagomir alleviated, while miR-31-5p agomir exacerbated LPS-induced inflammation, oxidative damage, and pulmonary dysfunction in vivo and in vitro. Mechanistically, miR-31-5p antagomir activated AMPKα to exert the protective effects that were abrogated by AMPKα inhibition. Further studies revealed that Cab39 was required for AMPKα activation and pulmonary protection by miR-31-5p antagomir. We provide the evidence that endogenous miR-31-5p is a key pathogenic factor for inflammation and oxidative damage during LPS-induced ALI, which is related to Cab39-dependent inhibition of AMPKα.

Meteorin-like protein attenuates doxorubicin-induced cardiotoxicity via activating cAMP/PKA/SIRT1 pathway

Meteorin-like (METRNL) protein is a newly identified myokine that functions to modulate energy expenditure and inflammation in adipose tissue. Herein, we aim to investigate the potential role and molecular basis of METRNL in doxorubicin (DOX)-induced cardiotoxicity. METRNL was found to be abundantly expressed in cardiac muscle under physiological conditions that was decreased upon DOX exposure. Cardiac-specific overexpression of METRNL by adeno-associated virus serotype 9 markedly improved oxidative stress, apoptosis, cardiac dysfunction and survival status in DOX-treated mice. Conversely, knocking down endogenous METRNL by an intramyocardial injection of adenovirus exacerbated DOX-induced cardiotoxicity and death. Meanwhile, METRNL overexpression attenuated, while METRNL silence promoted oxidative damage and apoptosis in DOX-treated H9C2 cells. Systemic METRNL depletion by a neutralizing antibody aggravated DOX-related cardiac injury and dysfunction in vivo, which were notably alleviated by METRNL overexpression within the cardiomyocytes. Besides, we detected robust METRNL secretion from isolated rodent hearts and cardiomyocytes, but to a less extent in those with DOX treatment. And the beneficial effects of METRNL in H9C2 cells disappeared after the incubation with a METRNL neutralizing antibody. Mechanistically, METRNL activated SIRT1 via the cAMP/PKA pathway, and its antioxidant and antiapoptotic capacities were blocked by SIRT1 deficiency. More importantly, METRNL did not affect the tumor-killing action of DOX in 4T1 breast cancer cells and tumor-bearing mice. Collectively, cardiac-derived METRNL activates SIRT1 via cAMP/PKA signaling axis in an autocrine manner, which ultimately improves DOX-elicited oxidative stress, apoptosis and cardiac dysfunction. Targeting METRNL may provide a novel therapeutic strategy for the prevention of DOX-associated cardiotoxicity.

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METRNL is abundant in the heart, yet decreased upon DOX treatment.

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METRNL overexpression improves, while METRNL deficiency exacerbates DOX-induced cardiotoxicity in vivo and in vitro.

•

METRNL activates SIRT1 via cAMP/PKA signaling axis in an autocrine manner.

•

METRNL does not affect the tumor-killing action of DOX in cancer cells.

Coumestrol ameliorates doxorubicin-induced cardiotoxicity via activating AMPKα

Doxorubicin (DOX) acts as the cornerstone in multiple tumour chemotherapy regimens, however, its clinical application is often impeded due to the induction of a severe cardiotoxicity that eventually provokes left ventricular dysfunction and congestive heart failure. Coumestrol (CMT) is a common dietary phytoestrogen with pleiotropic pharmacological effects. The present study aims to investigate the role and mechanism of CMT on DOX-induced cardiotoxicity. Mice were intragastrically administrated with CMT (5 mg/kg/day) for consecutive 2 weeks and then received a single intraperitoneal injection of DOX (15 mg/kg) to mimic the clinical toxic effects after 8-day additional feeding. To verify the role of 5' AMP-activated protein kinase alpha (AMPKα), AMPKα2 global knockout mice were used. H9C2 cells were cultured to further validate the beneficial role of CMT in vitro. CMT administration notably ameliorated oxidative damage, cell apoptosis and cardiac dysfunction in DOX-treated mice. Besides, we observed that DOX-induced reactive oxygen species overproduction and cardiomyocyte apoptosis were also reduced by CMT incubation in H9C2 cells. Mechanistically, CMT activated AMPKα and Ampkα deficiency abolished the beneficial effects of CMT in vivo and in vitro. Finally, we proved that protein kinase A (PKA) was required for CMT-mediated AMPKα activation and cardioprotective effects. CMT activated PKA/AMPKα pathway to alleviate DOX-induced oxidative damage, cell apoptosis and cardiac dysfunction. Our findings provide a promising therapeutic agent for cancer patients receiving anthracycline chemotherapy.

Toll-like receptor 5 deficiency diminishes doxorubicin-induced acute cardiotoxicity in mice

Rationale: Clinical application of doxorubicin (DOX) is limited by its toxic cardiovascular side effects. Our previous study found that toll-like receptor (TLR) 5 deficiency attenuated cardiac fibrosis in mice. However, the role of TLR5 in DOX-induced cardiotoxicity remains unclear.

Methods: To further investigate this, TLR5-deficient mice were subjected to a single intraperitoneal injection of DOX to mimic an acute model.

Results: Here, we reported that TLR5 expression was markedly increased in response to DOX injection. Moreover, TLR5 deficiency exerted potent protective effects against DOX-related cardiac injury, whereas activation of TLR5 by flagellin exacerbated DOX injection-induced cardiotoxicity. Mechanistically, the effects of TLR5 were largely attributed to direct interaction with spleen tyrosine kinase to activate NADPH oxidase (NOX) 2, increasing the production of superoxide and subsequent activation of p38. The toxic effects of TLR5 activation in DOX-related acute cardiac injury were abolished by NOX2 deficiency in mice. Our further study showed that neutralizing antibody-mediated TLR5 depletion also attenuated DOX-induced acute cardiotoxicity.

Conclusion: These findings suggest that TLR5 deficiency attenuates DOX-induced cardiotoxicity in mice, and targeting TLR5 may provide feasible therapies for DOX-induced acute cardiotoxicity.

SERCA overexpression reduces reperfusion-mediated cardiac microvascular damage through inhibition of the calcium/MCU/mPTP/necroptosis signaling pathways

Endothelial cells lining the microvasculature are particularly vulnerable to the deleterious effects of cardiac ischemia/reperfusion (I/R) injury, a susceptibility that is partially mediated by dysregulated intracellular calcium signals. Sarco/endoplasmic reticulum Ca²⁺-ATPase (SERCA) functions to recycle calcium from the cytosol back to the endoplasmic reticulum. The purpose of this study is to explore the roles and mechanisms of SERCA in protecting microcirculation against cardiac I/R injury. Our data showed that overexpression of SERCA significantly reduced I/R-induced luminal stenosis and vascular wall edema, possibly through normalization of the ratio between eNOS and ET-1. I/R-induced erythrocyte morphological changes in micro-vessels could be reversed by SERCA overexpression through transcriptional inhibition of the expression of adhesive factors. In addition, SERCA-sustained endothelial barrier integrity reduced the likelihood of inflammatory cells infiltrating the myocardium. Furthermore, we found that SERCA overexpression attenuated intracellular calcium overload, suppressed mitochondrial calcium uniporter (MCU) expression, and prevented the abnormal opening of mitochondrial permeability transition pores (mPTP) in I/R-treated cardiac microvascular endothelial cells (CMECs). Interestingly, the administration of calcium activator or MCU agonist induced endothelial necroptosis in vitro and thus abolished the microvascular protection afforded by SERCA in reperfused heart tissue in vivo. In conclusion, by using gene delivery strategies to specifically target SERCA in vitro and in vivo, we identify a potential novel pathway by which SERCA overexpression protects microcirculation against cardiac I/R injury in a manner dependent on the calcium/MCU/necroptosis pathway. These findings should be taken into consideration in the development of pharmacological strategies for therapeutic interventions against cardiac microvascular I/R injury.

Follistatin-Like 1 Protects against Doxorubicin-Induced Cardiomyopathy through Upregulation of Nrf2

Doxorubicin- (DOX-) induced cardiomyocyte loss results in irreversible heart failure, which limits the clinical applications of DOX. Currently, there are no drugs that can effectively treat DOX-related cardiotoxicity. Follistatin-like 1 (FSTL1) has been reported to be a transforming growth factor-beta-inducible gene, and FSTL1 supplementation attenuated ischemic injury and cardiac apoptotic loss in mice. However, the effect of FSTL1 on DOX-induced cardiomyopathy has not been elucidated. We aimed to explore whether FSTL1 could prevent DOX-related cardiotoxicity in mice. Mice were intraperitoneally injected with a single dose of DOX to induce acute cardiotoxicity. We used an adeno-associated virus system to overexpress FSTL1 in the heart. DOX administration decreased FSTL1 mRNA and protein expression in the heart and in cells. FSTL1 prevented DOX-related cardiac injury and inhibited cardiac oxidative stress and apoptosis, thereby improving cardiac function in mice. FSTL1 also improved cardiomyocyte contractile functions in vitro. FSTL1 upregulated expression of nuclear factor (erythroid-derived 2)-like 2 (Nrf2) in DOX-treated hearts. FSTL1 was not capable of protecting against these toxic effects in Nrf2-deficient mice. In conclusion, FSTL1 protected against DOX-induced cardiotoxicity via upregulation of Nrf2 expression.

Osteocrin attenuates inflammation, oxidative stress, apoptosis, and cardiac dysfunction in doxorubicin-induced cardiotoxicity

Background

Inflammation, oxidative stress, and apoptosis contribute to the evolution of doxorubicin (DOX)‐induced cardiotoxicity. Osteocrin (OSTN) is a novel secretory peptide mainly derived from the bone and skeletal muscle, and plays critical roles in regulating bone growth and physical endurance. Inspiringly, OSTN was also reported to be abundant in the myocardium that functioned as a therapeutic agent against cardiac rupture and congestive heart failure in mice after myocardial infarction. Herein, we investigated the role and potential mechanism of OSTN in DOX‐induced cardiotoxicity.

Methods

Cardiac‐restrict OSTN overexpression was performed by the intravenous injection of a cardiotropic AAV9 vector, and subsequently the mice received 15 mg/kg DOX injection (i.p., once) to induce acute cardiac injury. Besides, H9C2 cell lines were used to assess the possible role of OSTN in vitro by incubating with recombinant human OSTN or small interfering RNA against Ostn (siOstn). To clarify the involvement of protein kinase G (PKG), KT5823 and siPkg were used in vivo and in vitro. Mice were also administrated intraperitoneally with 5 mg/kg DOX weekly for consecutive 3 weeks at a cumulative dose of 15 mg/kg to mimic the cardiotoxic effects upon chronic DOX exposure.

Results

OSTN treatment notably attenuated, whereas OSTN silence exacerbated inflammation, oxidative stress, and cardiomyocyte apoptosis in DOX‐treated H9C2 cells. Besides, cardiac‐restrict OSTN‐overexpressed mice showed an alleviated cardiac injury and malfunction upon DOX injection. Mechanistically, we found that OSTN activated PKG, while PKG inhibition abrogated the beneficial effect of OSTN in vivo and in vitro. As expected, OSTN overexpression also improved cardiac function and survival rate in mice after chronic DOX treatment.

Conclusions

OSTN protects against DOX‐elicited inflammation, oxidative stress, apoptosis, and cardiac dysfunction via activating PKG, and cardiac gene therapy with OSTN provides a novel therapeutic strategy against DOX‐induced cardiotoxicity.

CTRP1 prevents sepsis-induced cardiomyopathy via Sirt1-dependent pathways

C1q/tumor necrosis factor-related protein 1 (CTRP1) has recently been identified as a key regulator of cardio-metabolic diseases. It has been reported that CTRP1 could inhibit the hypertrophic response in mice. However, the effect of CTRP1 on sepsis-induced cardiomyopathy remains completely unknown. Cardiomyocyte-specific CTRP1 overexpression was achieved using an adeno associated virus system in mice. CTRP1 deficiency mice were also subjected to lipopolysaccharide (LPS) injection. We found that CTRP1 overexpression improved survival rate and cardiac function, and suppressed myocardial inflammation, oxidative damage and apoptosis without affecting metabolic disturbance in LPS-treated mice. CTRP1 depletion further decreased survival rate and cardiac function, and promoting myocardial inflammation, oxidative damage and apoptosis in sepsis mice. In addition, we showed that CTRP1 provided protection against LPS-induced cell injury in vitro. CTRP1 activated sirtuin 1 (Sirt1) signaling pathway, and Sirt1 inhibition or deficiency blocked CTRP1-mediated cardioprotective effects in vivo and in vitro. More importantly, our study found that recombinant human globular domain of CTRP1 infusion was also capable of blocking sepsis-induced cardiomyopathy in mice. In conclusion, CTRP1 improved survival rate and attenuated LPS-induced cardiac injury via activating Sirt1 signaling pathway.

Geniposide protects against sepsis-induced myocardial dysfunction through AMPKα-dependent pathway

Uncontrolled inflammatory response and subsequent cardiomyocytes loss (apoptosis and pyroptosis) are closely involved in sepsis-induced myocardial dysfunction. Our previous study has found that geniposide (GE) can protect the murine hearts against obesity-induced inflammation. However, the effect of GE on sepsis-related cardiac dysfunction is still unknown. Mice were exposed to lipopolysaccharide (LPS) to generate sepsis-induced myocardial dysfunction. And 50 mg/kg GE was used to treat mice for consecutive 7 days. Our results showed that GE treatment significantly improved survival rate and cardiac function, and suppressed myocardial inflammatory response, as well as myocardial loss in LPS-treated mice. Those effects of GE were largely abolished in NOD-like receptor protein 3 (NLRP3)-deficient mice. Further detection revealed that the inhibition of NLRP3 inflammasome activation depended on the reduction of p47phox by GE. GE treatment restored the phosphorylation and activity of AMP-activated protein kinase α (AMPKα) in the hearts of sepsis mice, and knockout of AMPKα abolished the protection of GE against reactive oxygen species (ROS) accumulation, NLRP3 inflammasome activation and cardiomyocytes loss in sepsis mice. In conclusion, our findings revealed that GE activated AMPKα to suppress myocardial ROS accumulation, thus blocking NLRP3 inflammasome-mediated cardiomyocyte apoptosis and pyroptosis and improving cardiac function in mice with sepsis.

Asiatic Acid Protects against Doxorubicin-Induced Cardiotoxicity in Mice

The use of doxorubicin (DOX) can result in depression of cardiac function and refractory cardiomyopathy. Currently, there are no effective approaches to prevent DOX-related cardiac complications. Asiatic acid (AA) has been reported to provide cardioprotection against several cardiovascular diseases. However, whether AA could attenuate DOX-related cardiac injury remains unclear. DOX (15 mg/kg) was injected intraperitoneally into the mice to mimic acute cardiac injury, and the mice were given AA (10 mg/kg or 30 mg/kg) for 2 weeks for protection. The data in our study found that AA-treated mice exhibited attenuated cardiac injury and improved cardiac function in response to DOX injection. AA also suppressed myocardial oxidative damage and apoptosis without affecting cardiac inflammation in DOX-treated mice. AA also provided protection in DOX-challenged cardiomyocytes, improved cell viability, and suppressed intracellular reactive oxygen species (ROS) in vitro. Detection of signaling pathways showed that AA activated protein kinase B (AKT) signaling pathway in vivo and in vitro. Furthermore, we found that AA lost its protective effects in the heart with AKT inactivation. In conclusion, our results found that AA could attenuate DOX-induced myocardial oxidative stress and apoptosis via activation of the AKT signaling pathway.

Tetrandrine Attenuated Doxorubicin-Induced Acute Cardiac Injury in Mice

Oxidative damage is closely involved in the development of doxorubicin- (DOX-) induced cardiotoxicity. It has been reported that tetrandrine can prevent the development of cardiac hypertrophy by suppressing reactive oxygen species- (ROS-) dependent signaling pathways in mice. However, whether tetrandrine could attenuate DOX-related cardiotoxicity remains unclear. To explore the protective effect of tetrandrine, mice were orally given a dose of tetrandrine (50 mg/kg) for 4 days beginning one day before DOX injection. To induce acute cardiac injury, the mice were exposed to a single intraperitoneal injection of DOX (15 mg/kg). The data in our study showed that tetrandrine prevented DOX-related whole-body wasting and heart atrophy, decreased markers of cardiac injury, and improved cardiac function in mice. Moreover, tetrandrine supplementation protected the mice against oxidative damage and myocardial apoptotic death. Tetrandrine supplementation also reduced ROS production and improved cell viability after DOX exposure in vitro. We also found that tetrandrine supplementation increased nuclear factor (erythroid-derived 2)-like 2 (Nrf2) expression and activity in vivo and in vitro. The protection of tetrandrine supplementation was blocked by Nrf2 deficiency in mice. In conclusion, our study found that tetrandrine could improve cardiac function and prevent the development of DOX-related cardiac injury through activation of Nrf2.

New insights into the role of mitochondria in cardiac microvascular ischemia/reperfusion injury

As reperfusion therapies have become more widely used in acute myocardial infarction patients, ischemia-induced myocardial damage has been markedly reduced, but reperfusion-induced cardiac injury has become increasingly evident. The features of cardiac ischemia-reperfusion (I/R) injury include microvascular perfusion defects, platelet activation and sequential cardiomyocyte death due to additional ischemic events at the reperfusion stage. Microvascular obstruction, defined as a no-reflow phenomenon, determines the infarct zone, myocardial function and peri-operative mortality. Cardiac microvascular endothelial cell injury may occur much earlier and with much greater severity than cardiomyocyte injury. Endothelial cells contain fewer mitochondria than other cardiac cells, and several of the pathological alterations during cardiac microvascular I/R injury involve mitochondria, such as increased mitochondrial reactive oxygen species (mROS) levels and disturbed mitochondrial dynamics. Although mROS are necessary physiological second messengers, high mROS levels induce oxidative stress, endothelial senescence and apoptosis. Mitochondrial dynamics, including fission, fusion and mitophagy, determine the shape, distribution, size and function of mitochondria. These adaptive responses modify extracellular signals and orchestrate intracellular processes such as cell proliferation, migration, metabolism, angiogenesis, permeability transition, adhesive molecule expression, endothelial barrier function and anticoagulation. In this review, we discuss the involvement of mROS and mitochondrial morphofunction in cardiac microvascular I/R injury.

Mitochondrial quality control in cardiac microvascular ischemia-reperfusion injury: New insights into the mechanisms and therapeutic potentials

Thrombolytic therapy and revascularization strategies create a complete recanalization of the occluded epicardial coronary artery in patients with myocardial infarction (MI). However, about 35 % of patients still experience an impaired myocardial reperfusion, which is termed a no-reflow phenomenon mainly caused by cardiac microvascular ischemia-reperfusion (I/R) injury. Mitochondria are essential for microvascular endothelial cells' survival, both because of their roles as metabolic energy producers and as regulators of programmed cell death. Mitochondrial structure and function are regulated by a mitochondrial quality control (MQC) system, a series of processes including mitochondrial biogenesis, mitochondrial dynamics/mitophagy, mitochondrial proteostasis, and mitochondria-mediated cell death. Our review discusses the MQC mechanisms and how they are linked to cardiac microvascular I/R injury. Additionally, we will summarize the molecular basis that results in defective MQC mechanisms and present potential therapeutic interventions for improving MQC in cardiac microvascular I/R injury.

Role of mitochondrial quality control in the pathogenesis of nonalcoholic fatty liver disease

Nutrient oversupply and mitochondrial dysfunction play central roles in nonalcoholic fatty liver disease (NAFLD). The mitochondria are the major sites of β-oxidation, a catabolic process by which fatty acids are broken down. The mitochondrial quality control (MQC) system includes mitochondrial fission, fusion, mitophagy and mitochondrial redox regulation, and is essential for the maintenance of the functionality and structural integrity of the mitochondria. Excessive and uncontrolled production of reactive oxygen species (ROS) in the mitochondria damages mitochondrial components, including membranes, proteins and mitochondrial DNA (mtDNA), and triggers the mitochondrial pathway of apoptosis. The functionality of some damaged mitochondria can be restored by fusion with normally functioning mitochondria, but when severely damaged, mitochondria are segregated from the remaining functional mitochondrial network through fission and are eventually degraded via mitochondrial autophagy, also called as mitophagy. In this review, we describe the functions and mechanisms of mitochondrial fission, fusion, oxidative stress and mitophagy in the development and progression of NAFLD.

Cerebral ischemia-reperfusion is modulated by macrophage-stimulating 1 through the MAPK-ERK signaling pathway

Cerebral ischemia-reperfusion (IR) injury is associated with mitochondrial damage. Macrophage-stimulating 1 (MST1) reportedly stimulates mitochondrial apoptosis by suppressing BCL-2. We investigated whether MST1 promotes the progression of cerebral IR injury by inducing mitochondrial dysfunction in vivo and in vitro. Western blot analysis, quantitative polymerase chain reaction, immunofluorescence, and mitochondrial function assays were conducted in cells from wild-type and Mst1-knockout mice subjected to cerebral IR injury. MST1 expression in wild-type glial cells increased following cerebral IR injury. Cerebral IR injury reduced the mitochondrial membrane potential and mitochondrial metabolism in glial cells, while it enhanced mitochondrial reactive oxygen species generation and mitochondrial calcium levels in these cells. The deletion of Mst1 attenuated cerebral IR injury by improving mitochondrial function and reducing mitochondrial damage. The mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK) pathway was suppressed in wild-type glial cell upon cerebral IR injury but was reactivated in Mst1-knockout glial cell. Accordingly, blocking the MAPK/ERK pathway abolished the beneficial effects of Mst1 deletion during cerebral IR injury by inducing mitochondrial damage in glial cells. Our results suggest that cerebral IR injury is associated with MST1 upregulation in the brain, while the genetic ablation of Mst1 can attenuate mitochondrial damage and sustain brain function following cerebral IR injury.

Mief1 augments thyroid cell dysfunction and apoptosis through inhibiting AMPK-PTEN signaling pathway

Objective: Inflammation-mediated thyroid cell dysfunction and apoptosis increases the like-hood of hypothyroidism.Aim: Our aim in the present study is to explore the role of mitochondrial elongation factor 1 (Mief1) in thyroid cell dysfunction induced by TNFα.Materials and methods: Different doses of TNFα were used to incubate with thyroid cells in vitro. The survival rate, apoptotic index and proliferation capacity of thyroid cells were measured. Cellular energy metabolism and endoplasmic reticulum function related to protein synthesis were detected.Results: In response to TNFα treatment, the levels of Mief1 were increased, coinciding with a drop in the viability of thyroid cells in vitro. Loss of Mief1 attenuates TNFα-induced cell death through reducing the ratio of cell apoptosis. Further, we found that Mief1 deletion reversed cell energy metabolism and this effect was attributable to mitochondrial protection. Mief1 knockdown sustained mitochondrial membrane potential and reduced mitochondrial ROS overproduction. In addition, Mief1 knockdown also reduced endoplasmic reticulum stress, as evidenced by decreased levels of Chop and Caspase-12. Finally, our data verified that TNFα treatment inhibited the activity of AMPK-PTEN pathway whereas Mief1 deletion reversed the activity of AMPK and thus promoted the upregulation of PTEN. However, inhibition of AMPK-PTEN pathways could abolish the beneficial effects exerted by Mief1 deletion on thyroid cells damage and dysfunction.Conclusions: Altogether, our data indicate that immune abnormality-mediated thyroid cell dysfunction and death are alleviated by Mief1 deletion possible driven through reversing the activity of AMPK-PTEN pathways.

SRV2 promotes mitochondrial fission and Mst1-Drp1 signaling in LPS-induced septic cardiomyopathy

Mitochondrial fission is associated with cardiomyocyte death and myocardial depression, and suppressor of ras val-2 (SRV2) is a newly discovered pro-fission protein. In this study, we examined the mechanisms of SRV2-mediated mitochondrial fission in septic cardiomyopathy. Western blotting, ELISA, and immunofluorescence were used to evaluate mitochondrial function, oxidative balance, energy metabolism and caspase-related death, and siRNA and adenoviruses were used to perform loss- and gain-of-function assays. Our results demonstrated that increased SRV2 expression promotes, while SRV2 knockdown attenuates, cardiomyocyte death in LPS-induced septic cardiomyopathy. Mechanistically, SRV2 activation promoted mitochondrial fission and physiological abnormalities by upregulating oxidative injury, ATP depletion, and caspase-9-related apoptosis. Our results also demonstrated that SRV2 promotes mitochondrial fission via a Mst1-Drp1 axis. SRV2 knockdown decreased Mst1 and Drp1 levels, while Mst1 overexpression abolished the mitochondrial protection and cardiomyocyte survival-promoting effects of SRV2 knockdown. SRV2 is thus a key novel promotor of mitochondrial fission and Mst1-Drp1 axis activity in septic cardiomyopathy.

Yes-associated protein reduces neuroinflammation through upregulation of Sirt3 and inhibition of JNK signaling pathway

Objective: Neuroinflammation is linked to a series of neurodegenerative diseases through the unknown mechanisms.Aim: The aim of this study was to investigate the role of Yes-associated protein (Yap) in the regulation of neuroinflammation.Methods: BV-2 neuroglia cells were treated with TNFα in vitro. Then, western blots, qPCR, immunofluorescence, and ELISA were used to verify the influence of Yap in BV-2 cells neuroinflammation response.Results: After exposure to TNFα, viability of BV-2 cells decreased whereas apoptosis index was increased. Of note, Yap expression in BV-2 cells was significantly reduced, when compared to the normal cells. Interestingly, adenovirus-induced Yap overexpression was capable to reverse cell viability and thus reduce apoptotic index in TNFα-treated BV-2 cells. Molecular investigation demonstrated that Yap overexpression was linked to Sirt3 upregulation. Increased Sirt3 reduced endoplasmic reticulum (ER) stress, attenuated mitochondrial damage, and blocked JNK pro-apoptotic pathway. Interestingly, loss of Sirt3 abolished the protective effects induced by Yap overexpression in TNFα-treated BV-2 cells.Conclusions: Altogether, our results demonstrated that neuroinflammation could be caused by Yap downregulation, possible driven through Sirt3 inhibition and JNK activation. However, overexpression of Yap could protect BV-2 cells against TNFα-mediated apoptosis through modulating Sirt3-JNK signaling pathways.

Piperine Alleviates Doxorubicin-Induced Cardiotoxicity via Activating PPAR-γ in Mice

Background

Oxidative stress, inflammation and cardiac apoptosis were closely involved in doxorubicin (DOX)-induced cardiac injury. Piperine has been reported to suppress inflammatory response and pyroptosis in macrophages. However, whether piperine could protect the mice against DOX-related cardiac injury remain unclear. This study aimed to investigate whether piperine inhibited DOX-related cardiac injury in mice.

Methods

To induce DOX-related acute cardiac injury, mice in DOX group were intraperitoneally injected with a single dose of DOX (15 mg/kg). To investigate the protective effects of piperine, mice were orally treated for 3 weeks with piperine (50 mg/kg, 18:00 every day) beginning two weeks before DOX injection.

Results

Piperine treatment significantly alleviated DOX-induced cardiac injury, and improved cardiac function. Piperine also reduced myocardial oxidative stress, inflammation and apoptosis in mice with DOX injection. Piperine also improved cell viability, and reduced oxidative damage and inflammatory factors in cardiomyocytes. We also found that piperine activated peroxisome proliferator-activated receptor-γ (PPAR-γ), and the protective effects of piperine were abolished by the treatment of the PPAR-γ antagonist in vivo and in vitro.

Conclusions

Piperine could suppress DOX-related cardiac injury via activation of PPAR-γ in mice.

LATS2 promotes cardiomyocyte H9C2 cells apoptosis via the Prx3-Mfn2-mitophagy pathways

Context: The pathogenesis of cardiomyocyte death is closely associated with mitochondrial homeostasis via poorly understood mechanisms.Objective: The aim of our study is to explore the contribution of large tumor suppressor kinase 2 (LATS2) to the apoptosis of cardiomyocyte H9C2 cells.Materials and Methods: Adenovirus-mediated LATS2 overexpression was carried out in H9C2 cells. The cell viability and apoptosis rate were measured via an MTT assay, TUNEL staining, western blotting, an ELISA, and an LDH release assay. Mitophagy was quantified using immunofluorescence and western blotting.Results: The overexpression of LATS2 in H9C2 cells drastically promoted cell death. Molecular investigations showed that LATS2 overexpression was associated with mitochondrial injury, as evidenced by increased mitochondrial ROS production, reduced antioxidant factor levels, increased cyt-c liberation into the nucleus and activated mitochondrial caspase-9-dependent apoptotic pathway activity. Furthermore, our results demonstrated that LATS2-mediated mitochondrial malfunction by repressing mitophagy and that the reactivation of mitophagy could sustain mitochondrial integrity and homeostasis in response to LATS2 overexpression. Furthermore, we found that LATS2 inhibited mitophagy by inactivating the Prx3-Mfn2 axis. The reactivation of Prx3-Mfn2 pathways abrogated the LATS2-mediated inhibition of mitochondrial apoptosis in H9C2 cells.Conclusions: The overexpression of LATS2 induces mitochondrial stress by repressing protective mitophagy in a manner dependent on Prx3-Mfn2 pathways, thus reducing the survival of H9C2 cells.

miR-200a Attenuated Doxorubicin-Induced Cardiotoxicity through Upregulation of Nrf2 in Mice

Nuclear factor (erythroid-derived 2)-like 2 (Nrf2) was closely involved in doxorubicin- (DOX-) induced cardiotoxicity. MicroRNA-200a (miR-200a) could target Keap1 mRNA and promote degradation of Keap1 mRNA, resulting in Nrf2 activation. However, the role of miR-200a in DOX-related cardiotoxicity remained unclear. Our study is aimed at investigating the effect of miR-200a on DOX-induced cardiotoxicity in mice. For cardiotropic expression, male mice received an injection of an adeno-associated virus 9 (AAV9) system carrying miR-200a or miR-scramble. Four weeks later, mice received a single intraperitoneal injection of DOX at 15 mg/kg. In our study, we found that miR-200a mRNA was the only microRNA that was significantly decreased in DOX-treated mice and H9c2 cells. miR-200a supplementation blocked whole-body wasting and heart atrophy caused by acute DOX injection, decreased the levels of cardiac troponin I and the N-terminal probrain natriuretic peptide, and improved cardiac and adult cardiomyocyte contractile function. Moreover, miR-200a reduced oxidative stress and cardiac apoptosis without affecting matrix metalloproteinase and inflammatory factors in mice with acute DOX injection. miR-200a also attenuated DOX-induced oxidative injury and cell loss in vitro. As expected, we found that miR-200a activated Nrf2 and Nrf2 deficiency abolished the protection provided by miR-200a supplementation in mice. miR-200a also provided cardiac benefits in a chronic model of DOX-induced cardiotoxicity. In conclusion, miR-200a protected against DOX-induced cardiotoxicity via activation of the Nrf2 signaling pathway. Our data suggest that miR-200a may represent a new cardioprotective strategy against DOX-induced cardiotoxicity.

CTRP3 Protects against High Glucose-Induced Cell Injury in Human Umbilical Vein Endothelial Cells

Aims

Inflammation was closely associated with diabetes-related endothelial dysfunction. C1q/tumor necrosis factor-related protein 3 (CTRP3) is a member of the CTRP family and can provide cardioprotection in many cardiovascular diseases via suppressing the production of inflammatory factors. However, the role of CTRP3 in high glucose- (HG-) related endothelial dysfunction remains unclear. This study evaluates the effects of CTRP3 on HG-induced cell inflammation and apoptosis.

Materials and Methods

To prevent high glucose-induced cell injury, human umbilical vein endothelial cells (HUVECs) were pretreated with recombinant CTRP3 for 1 hour followed by normal glucose (5.5 mmol/l) or high glucose (33 mmol/l) treatment. After that, cell apoptosis and inflammatory factors were determined.

Results

Our results demonstrated that CTRP3 mRNA and protein expression were significantly decreased after HG exposure in HUVECs. Recombinant human CTRP3 inhibited HG-induced accumulation of inflammatory factors and cell loss in HUVECs. CTRP3 treatment also increased the phosphorylation levels of protein kinase B (AKT/PKB) and the mammalian target of rapamycin (mTOR) in HUVECs. CTRP3 lost its inhibitory effects on HG-induced cell inflammation and apoptosis after AKT inhibition. Knockdown of endogenous CTRP3 in HUVECs resulted in increased inflammation and decreased cell viability in vitro.

Conclusions

Taken together, these findings indicated that CTRP3 treatment blocked the accumulation of inflammatory factors and cell loss in HUVECs after HG exposure through the activation of AKT-mTOR signaling pathway. Thus, CTRP3 may be a potential therapeutic drug for the prevention of diabetes-related endothelial dysfunction.

miR-451 Silencing Inhibited Doxorubicin Exposure-Induced Cardiotoxicity in Mice

Oxidative stress and cardiomyocytes apoptosis were closely involved in the pathological process of doxorubicin- (Dox-) induced cardiac injury. MicroRNA-451 (miR-451) was mainly expressed in cardiomyocytes. However, the role of miR-451 in Dox-induced cardiac injury remained unclear. Our study aimed to investigate the effect of miR-451 on Dox-induced cardiotoxicity in mice. We established a Dox-induced cardiotoxicity model in the mice and manipulated miR-451 expression in the heart using a miR-451 inhibitor, which was injected every other day beginning at one day before Dox injection. Oxidative stress and apoptosis in the hearts were evaluated. miR-451 levels were significantly increased in Dox-treated mice or cardiomyocytes. miR-451 inhibition attenuated Dox-induced whole-body wasting and heart atrophy, reduced cardiac injury, restored cardiac function, and improved cardiomyocyte contractile function. Moreover, miR-451 inhibition reduced oxidative stress and cardiomyocytes apoptosis in vivo and in vitro. miR-451 inhibition increased the expression of calcium binding protein 39 (Cab39) and activated adenosine monophosphate activated protein kinase (AMPK) signaling pathway. A specific inhibitor of AMPK abolished the protection provided by miR-451 inhibition against cell injury in vitro. In conclusion, miR-451 inhibition protected against Dox-induced cardiotoxicity via activation of AMPK signaling pathway.

Protection against Doxorubicin-Induced Cytotoxicity by Geniposide Involves AMPKα Signaling Pathway

Oxidative stress and cardiomyocyte apoptosis play critical roles in the development of doxorubicin- (DOX-) induced cardiotoxicity. Our previous study found that geniposide (GE) could inhibit cardiac oxidative stress and apoptosis of cardiomyocytes but its role in DOX-induced heart injury remains unknown. Our study is aimed at investigating whether GE could protect against DOX-induced heart injury. The mice were subjected to a single intraperitoneal injection of DOX (15 mg/kg) to induce cardiomyopathy model. To explore the protective effects, GE was orally given for 10 days. The morphological examination and biochemical analysis were used to evaluate the effects of GE. H9C2 cells were used to verify the protective role of GE in vitro. GE treatment alleviated heart dysfunction and attenuated cardiac oxidative stress and cell loss induced by DOX in vivo and in vitro. GE could activate AMP-activated protein kinase α (AMPKα) in vivo and in vitro. Moreover, inhibition of AMPKα could abolish the protective effects of GE against DOX-induced oxidative stress and apoptosis. GE could protect against DOX-induced heart injury via activation of AMPKα. GE has therapeutic potential for the treatment of DOX cardiotoxicity.

FNDC5 alleviates oxidative stress and cardiomyocyte apoptosis in doxorubicin-induced cardiotoxicity via activating AKT

Oxidative stress and cardiomyocyte apoptosis play critical roles in doxorubicin (DOX)-induced cardiotoxicity. Previous studies indicated that fibronectin type III domain-containing 5 (FNDC5) and its cleaved form, irisin, could preserve mitochondrial function and attenuate oxidative damage as well as cell apoptosis, however, its role in DOX-induced cardiotoxicity remains unknown. Our present study aimed to investigate the role and underlying mechanism of FNDC5 on oxidative stress and cardiomyocyte apoptosis in DOX-induced cardiotoxicity. Cardiomyocyte-specific FNDC5 overexpression was achieved using an adeno-associated virus system, and then the mice were exposed to a single intraperitoneal injection of DOX (15 mg/kg) to generate DOX-induced cardiotoxicity. Herein, we found that FNDC5 expression was downregulated in DOX-treated murine hearts and cardiomyocytes. Fndc5 deficiency resulted in increased oxidative damage and apoptosis in H9C2 cells under basal conditions, imitating the phenotype of DOX-induced cardiomyopathy in vitro, conversely, FNDC5 overexpression or irisin treatment alleviated DOX-induced oxidative stress and cardiomyocyte apoptosis in vivo and in vitro. Mechanistically, we identified that FNDC5/Irisin activated AKT/mTOR signaling and decreased DOX-induced cardiomyocyte apoptosis, and moreover, we provided direct evidence that the anti-oxidant effect of FNDC5/Irisin was mediated by the AKT/GSK3β/FYN/Nrf2 axis in an mTOR-independent manner. And we also demonstrated that heat shock protein 20 was responsible for the activation of AKT caused by FNDC5/Irisin. In line with the data in acute model, we also found that FNDC5/Irisin exerted beneficial effects in chronic model of DOX-induced cardiotoxicity (5 mg/kg, i.p., once a week for three times, the total cumulative dose is 15 mg/kg) in mice. Based on these findings, we supposed that FNDC5/Irisin was a potential therapeutic agent against DOX-induced cardiotoxicity.

Immune cells as targets for cardioprotection: new players and novel therapeutic opportunities

New therapies are required to reduce myocardial infarct (MI) size and prevent the onset of heart failure in patients presenting with acute myocardial infarction (AMI), one of the leading causes of death and disability globally. In this regard, the immune cell response to AMI, which comprises an initial pro-inflammatory reaction followed by an anti-inflammatory phase, contributes to final MI size and post-AMI remodelling [changes in left ventricular (LV) size and function]. The transition between these two phases is critical in this regard, with a persistent and severe pro-inflammatory reaction leading to adverse LV remodelling and increased propensity for developing heart failure. In this review article, we provide an overview of the immune cells involved in orchestrating the complex and dynamic inflammatory response to AMI-these include neutrophils, monocytes/macrophages, and emerging players such as dendritic cells, lymphocytes, pericardial lymphoid cells, endothelial cells, and cardiac fibroblasts. We discuss potential reasons for past failures of anti-inflammatory cardioprotective therapies, and highlight new treatment targets for modulating the immune cell response to AMI, as a potential therapeutic strategy to improve clinical outcomes in AMI patients. This article is part of a Cardiovascular Research Spotlight Issue entitled 'Cardioprotection Beyond the Cardiomyocyte', and emerged as part of the discussions of the European Union (EU)-CARDIOPROTECTION Cooperation in Science and Technology (COST) Action, CA16225.

C1qTNF-related protein-6 protects against doxorubicin-induced cardiac injury

The clinical use of doxorubicin (DOX) is limited by its toxic effect. However, there is no specific drug that can prevent DOX-related cardiac injury. C1qTNF-related protein-6 (CTRP6) is a newly identified adiponectin paralog with many protective functions on metabolism and cardiovascular diseases. However, little is known about the effect of CTRP6 on DOX-induced cardiac injury. The present study aimed to investigate whether CTRP6 could protect against DOX-related cardiotoxicity. To induce acute cardiotoxicity, the mice were intraperitoneally injected with a single dose of DOX (15 mg/kg). Cardiomyocyte-specific CTRP6 overexpression was achieved using an adenoassociated virus system at 4 weeks before DOX injection. The data in our study demonstrated that CTRP6 messenger RNA and protein expression were decreased in DOX-treated hearts. CTRP6 attenuated cardiac atrophy induced by DOX injection and inhibited cardiac apoptosis and improved cardiac function in vivo. CTRP6 also promoted the activation of protein kinase B (AKT/PKB) signaling pathway in DOX-treated mice. CTRP6 prevented cardiomyocytes from DOX-induced apoptosis and activated the AKT pathway in vitro. CTRP6 lost its protection against DOX-induced cardiac injury in mice with AKT inhibition. In conclusion, CTRP6 protected the heart from DOX-cardiotoxicity and improves cardiac function via activation of the AKT signaling pathway.

miR‑216a exacerbates TGF‑β‑induced myofibroblast transdifferentiation via PTEN/AKT signaling

Myofibroblast transdifferentiation is an important feature of cardiac fibrosis. Previous studies have indicated that microRNA‑216a (miR‑216a) is upregulated in response to transforming growth factor‑β (TGF‑β) in kidney cells and can activate Smad3; however, its role in myofibroblast transdifferentiation remains unclear. The present study aimed to investigate the role of miR‑216a in TGF‑β‑induced myofibroblast transdifferentiation, and to determine the underlying mechanisms. Adult mouse cardiac fibroblasts were treated with TGF‑β to induce myofibroblast transdifferentiation. An antagomir and agomir of miR‑216a were used to inhibit or overexpress miR‑216a in cardiac fibroblasts, respectively. Myofibroblast transdifferentiation was evaluated based on the levels of fibrotic markers and α‑smooth muscle actin expression. The miR‑216a antagomir attenuated, whereas the miR‑216a agomir promoted TGF‑β‑induced myofibroblast transdifferentiation. Mechanistically, miR‑216a accelerated myofibroblast transdifferentiation via the AKT/glycogen synthase kinase 3β signaling pathway, independent of the canonical Smad3 pathway. In addition, it was observed that miR‑216a activated AKT via the downregulation of PTEN. In conclusion, miR‑216a was involved in the regulation of TGF‑β‑induced myofibroblast transdifferentiation, suggesting that targeting miR‑216a may aid in developing effective interventions for the treatment of cardiac fibrosis.

Sulforaphane ameliorates high-fat diet-induced spermatogenic deficiency in mice†

Sulforaphane (SFN), a dietary isothiocyanate that is mainly found in cruciferous vegetables, possesses anti-oxidative and anticancer activity and modulates inflammation. However, little is known about the role of SFN in obesity-related male reproductive defects. The present study aimed to investigate the effects of SFN on high-fat diet (HFD)-induced male spermatogenic impairment and further clarify the possible underlying mechanisms. In this study, 8-week-old mice were randomly divided into four groups. Mice were fed a normal diet or an HFD with or without SFN supplementation. Sulforaphane was subcutaneously injected at a dose of 0.5 mg/kg 5 days/week for 4 weeks beginning 8 weeks after initiation of the HFD. The results demonstrated that SFN could protect against HFD-induced reproductive dysfunction in male mice. Moreover, SFN also improved reproductive ability, as demonstrated by an increased pregnancy rate and decreased embryo resorption rate in comparison to the corresponding HFD group. We also observed a decrease in apoptosis and an attenuation of endoplasmic reticulum (ER) stress after SFN treatment. In vitro studies of mouse and human sperm samples also revealed that SFN protects against the palmitic acid-induced reduction in sperm viability and motility by inhibiting ER stress in an AMP-activated protein kinase (AMPK)-dependent manner. AMPK-dependent ER stress attenuation by SFN was further confirmed using AMPK knockout mice. Taken together, these data show that SFN protects against HFD-induced male reproductive dysfunction by inhibiting ER stress and apoptosis. These findings may be helpful for identifying new therapeutic methods to treat male infertility.

Rosmarinic acid alleviates cardiomyocyte apoptosis via cardiac fibroblast in doxorubicin-induced cardiotoxicity

Cardiomyocyte apoptosis is a key event in the process of doxorubicin (DOX)-induced cardiotoxicity. Our previous study found that rosmarinic acid (RA) could attenuate pressure overload-induced cardiac dysfunction via cardiac fibroblasts (CFs), however its effect in DOX-induced cardiotoxicity remains unknown. In the present study, mice were subjected to a single intraperitoneal injection of DOX (15mg/kg) to generate DOX-induced cardiotoxicity. Histological examination, echocardiography, and molecular markers were used to evaluate the effects of RA. Neonatal rat cardiomyocytes (CMs) and CFs were used to verify the protective effect of RA in vitro. Conditioned medium derived from RA-treated CFs were prepared to illustrate the effect of RA on paracrine interplay between CFs and CMs. We found that RA significantly alleviated DOX-induced cardiomyocyte apoptosis and cardiac dysfunction in vivo, which, however, had almost negligible beneficial effect on DOX directly induced cardiomyocyte apoptosis in vitro. Mechanistically, CFs-derived Fas L was responsible for DOX-induced cardiomyocyte apoptosis, and RA treatment could decrease Fas L expression in CFs and its release to the conditioned medium by suppressing nuclear factor of activated T cells (NFAT) activation and metalloproteinase 7 (MMP7) expression, and exerted the anti-apoptotic effect on CMs via CFs. Ionomycin, and activator of NFAT, abrogated RA-mediated protective effect on cardiomyocyte apoptosis and cardiac dysfunction. In summary, RA alleviated cardiomyocyte apoptosis by inhibiting the expression and release of Fas L in CFs via a paracrine manner, moreover, NFAT as well as MMP7 inhibition were responsible for the suppression of Fas L. RA could be a powerful new therapeutic agent to mitigate cardiomyocyte apoptosis, thereby improving DOX-induced cardiotoxicity.

Geniposide Protects against Obesity-Related Cardiac Injury through AMPKα- and Sirt1-Dependent Mechanisms

Our previous study found that geniposide, an agonist of glucagon-like peptide-1 receptor (GLP-1R), protected against cardiac hypertrophy via the activation of AMP-activated protein kinase α (AMPKα). However, the effects of geniposide on obesity-related cardiac injury remain unknown. Here, we examine whether geniposide attenuates obesity-related cardiac dysfunction. Adult mice were fed a high-fat diet (HFD) for 24 weeks to induce obesity, with the last 3 weeks including a 21-day treatment with geniposide. Morphological changes, cardiac function, and remodeling were assessed. HFD-induced metabolic syndrome, featured as obesity, hyperglycemia, and cardiac hypertrophy, was prevented by geniposide treatment. Geniposide preserved cardiac function in the obese mice. Furthermore, geniposide attenuated myocardial inflammation and myocyte apoptosis induced by HFD. Geniposide activated AMPKα and sirtuin (Sirt1) in vivo and in vitro. Ampkα deficiency reversed the inhibitory effects of geniposide on cell loss. Sirt1 deficiency abolished the inhibitory effects of geniposide on inflammation in the cardiomyocytes. Geniposide completely lost its protective effects on Ampkα knockout mice after Sirt1 deficiency achieved by a nanoparticle transfection reagent. The activation of Sirt1 by geniposide was abolished by Glp-1r deficiency in vitro. Geniposide reverses molecular pathology and cardiac dysfunction via both AMPKα- and Sirt1-dependent mechanisms. Geniposide is a potential therapeutic drug for cardiovascular complications induced by obesity.