STAT3 mediates cardioprotection against ischemia/reperfusion injury through metallothionein induction in the heart

The Role of P53 in Myocardial Ischemia-Reperfusion Injury

PURPOSE

P53 is one of the key tumor suppressors. In normal cells, p53 is maintained at low levels by the ubiquitination of the ubiquitinated ligase MDM2. In contrast, under stress conditions such as DNA damage and ischemia, the interaction between p53 and MDM2 is blocked and activated by phosphorylation and acetylation, thereby mediating the trans-activation of p53 through its target genes to regulate a variety of cellular responses. Previous studies have shown that the expression of p53 is negligible in normal myocardium, tends to increase in myocardial ischemia and is maximally induced in ischemia-reperfused myocardium, demonstrating a possible key role of p53 in the development of MIRI. In this review, we detail and summarize recent studies on the mechanism of action of p53 in MIRI and describe the therapeutic agents targeting the relevant targets to provide new strategies for the prevention and treatment of MIRI.

METHODS

We collected 161 relevant papers mainly from Pubmed and Web of Science (search terms "p53" and "myocardial ischemia-reperfusion injury"). After that, we selected pathway studies related to p53 and classified them according to their contents. We eventually analyzed and summarized them.

RESULTS AND CONCLUSION

In this review, we detail and summarize recent studies on the mechanism of action of p53 in MIRI and validate its status as an important intermediate affecting MIRI. On the one hand, p53 is regulated and modified by multiple factors, especially non-coding RNAs; on the other hand, p53 regulates apoptosis, programmed necrosis, autophagy, iron death and oxidative stress in MIRI through multiple pathways. More importantly, several studies have reported medications targeting p53-related therapeutic targets. These medications are expected to be effective options for the alleviation of MIRI, but further safety and clinical studies are needed to convert them into clinical applications.

Serpina3k lactylation protects from cardiac ischemia reperfusion injury

Lactate produced during ischemia-reperfusion injury is known to promote lactylation of proteins, which play controversial roles. By analyzing the lactylomes and proteomes of mouse myocardium during ischemia-reperfusion injury using mass spectrometry, we show that both Serpina3k protein expression and its lactylation at lysine 351 are increased upon reperfusion. Both Serpina3k and its human homolog, SERPINA3, are abundantly expressed in cardiac fibroblasts, but not  in cardiomyocytes. Biochemically, lactylation of Serpina3k enhances protein stability. Using Serpina3k knockout mice and mice overexpressing its lactylation-deficient mutant, we find that Serpina3k protects from cardiac injury in a lysine 351 lactylation-dependent manner. Mechanistically, ischemia-reperfusion-stimulated fibroblasts secrete Serpina3k/SERPINA3, and protect cardiomyocytes from reperfusion-induced apoptosis in a paracrine fashion, partially through the activation of cardioprotective reperfusion injury salvage kinase and survivor activating factor enhancement pathways. Our results demonstrate the pivotal role of protein lactylation in cardiac ischemia-reperfusion injury, which may hold therapeutic value.

Methamphetamine-induced cardiotoxicity: in search of protective transcriptional mechanisms

Crystalline methamphetamine hydrochloride is an illegal drug with a high addictive potential, better known by its colloquial name "ice" or "crystal meth". The abuse of this drug has led to significant health problems worldwide. Like other amphetamine-type stimulants, chronic consumption of methamphetamine leads to direct toxic effects on the central nervous system, causing cognitive impairment, depressive behavior, and other severe neurological or psychiatric symptoms. Besides its neurotoxicity, the drug exhibits numerous deleterious effects on the cardiovascular system, including hypertension, accelerated atherosclerosis, vasospasm-induced acute coronary syndromes, sudden cardiac death, and dilated cardiomyopathy with congestive heart failure and left ventricular dysfunction. The excessive release of catecholamines upon methamphetamine exposure causes vasoconstriction and vasospasm, which ultimately lead to hypertension, tachycardia, endothelial dysfunction, and cardiotoxicity. While numerous studies have focused on transcription factors expressed in the brain that cause the neurotoxic effects of the drug, much less is known about transcription factors involved in the development of methamphetamine-induced heart failure. In this article, we provide an overview of the Janus kinase-signal transducer and activator of transcription 3 (JAK-STAT3) pathway involved in ischemia/reperfusion injury in the myocardium, which may be activated by the vasospasm-inducing action of the drug. However, much more work is needed to decipher the precise role of STAT protein family members, including the potentially cardioprotective STAT3, in the pathogenesis of methamphetamine-induced cardiotoxicity.

Exploring putative drug properties associated with TNF-alpha inhibition and identification of potential targets in cardiovascular disease using machine learning-assisted QSAR modeling and virtual reverse pharmacology approach

Cardiovascular disease is a chronic inflammatory disease with high mortality rates. TNF-alpha is pro-inflammatory and associated with the disease, but current medications have adverse effects. Therefore, efficient inhibitors are urgently needed as alternatives. This study represents a structural-activity relationship investigation of TNF-alpha, curated from the ChEMBL database. Exploratory data analysis was performed to visualize the physicochemical properties of different bioactivity groups. The extracted molecules were subjected to PubChem and SubStructure fingerprints, and a QSAR-based Random Forest (QSAR-RF) model was generated using the WEKA tool. The QSAR random Forest model was built based on the SubStructure fingerprint with a correlation coefficient of 0.992 and 0.716 as the respective tenfold cross-validation scores. The variance important plot (VIP) method was used to extract the important features for TNF-alpha inhibition. The Substructure-based QSAR-RF (SS-QSAR-RF) model was validated using molecules from PubChem and ZINC databases. The generated model also predicts the pIC50 value of the molecules selected from the docking study followed by molecular dynamic simulation with the time step of 100 ns. Through virtual reverse pharmacology, we determined the main drug targets from the top four hit compounds obtained via molecular docking study. Our analysis included an integrated bioinformatics approach to pinpoint crucial targets like EGRF, HSP900A1, STAT3, PSEN1, AKT1, and MDM2. Further, GO and KEGG pathways analysis identified relevant cardiovascular disease-related pathways for the hub gene involved. However, this study provides valuable insights, it is important to note that it lacks experimental application. Future research may benefit from conducting in-vitro and in-vivo studies.

Cardioprotective effect of Interleukin-11 against warm ischemia-reperfusion injury in a rat heart donor model

Shortage of donor organs for heart transplantation is a worldwide problem. Donation after circulatory death (DCD) has been proposed to expand the donor pool. However, in contrast to the donation after brain death that undergoes immediate cold preservation, warm ischemia and subsequent reperfusion injury are inevitable in DCD. It has been reported that interleukin-11 (IL-11) mitigates ischemia-reperfusion injury in rodent models of myocardial infarction and donation after brain death heart transplantation. We hypothesized that IL-11 also offers benefit to warm ischemia in an experimental model of cardiac transplantation that resembles DCD. The hearts of naïve male Sprague Dawley rats (n = 15/group) were procured, subjected to 25-min warm ischemia, and reperfused for 60 min using Langendorff apparatus. IL-11 or saline was administered intravenously before the procurement, added to maintenance buffer, and infused via perfusion during reperfusion. IL-11 group exhibited significantly better cardiac function post-reperfusion. Severely damaged mitochondria was found in the electron microscopic analysis of control hearts whereas the mitochondrial structure was better preserved in the IL-11 treated hearts. Immunoblot analysis using neonatal rat cardiomyocytes revealed increased signal transducer and activator of transcription 3 (STAT3) phosphorylation at Ser727 after IL-11 treatment, suggesting its role in mitochondrial protection. Consistent with expected activation of mitochondrial respiration by mitochondrial STAT3, immunohistochemical staining demonstrated a higher mitochondrial cytochrome c oxidase subunit 2 expression. In summary, IL-11 protects the heart from warm ischemia reperfusion injury by alleviating mitochondrial injury and could be a viable therapeutic option for DCD heart transplantation.

Human peripheral blood mononuclear cells display a temporal evolving inflammatory profile after myocardial infarction and modify myocardial fibroblasts phenotype

Pathophysiological response after acute myocardial infarction (AMI) is described as a three-stage model involving temporal phenotypic modifications of both immune cells and fibroblasts: a primary inflammatory phase, followed by a reparative phase and a fibrous scar maturation phase. Purinergic receptors, particularly the P2Y11 receptor, have been reported to be involved in the regulation of inflammation after ischemia and could act for the resolution of inflammation after AMI. For the first time, we characterized the immuno-inflammatory and P2Y11 expression profiles of peripheral blood mononuclear cells (PBMC) from AMI patients and analyzed the consequences of presenting these cells to cardiac fibroblasts in vitro. PBMC from 178 patients were collected at various times after reperfused ST-segment elevation AMI, from H0 to M12. Expression level of P2RY11 and genes involved in tolerogenic profile of dendritic cells and T cell polarization were evaluated by RT-PCR. P2Y11 protein expression was assessed by flow cytometry. PBMC and human cardiac fibroblasts (HCF) were cocultured and α-SMA/vimentin ratio was analyzed by flow cytometry. Within the first 48 h after AMI, expression levels of HMOX1, STAT3 and CD4 increased while IDO1 and TBX21/GATA3 ratio decreased. Concomitantly, the expression of P2RY11 increased in both T and B cells. In vitro, PBMC collected at H48 after AMI induced an increase in α-SMA/vimentin ratio in HCF. Our results suggest that human PBMC display an evolving inflammatory profile with reparative characteristics the first two days after AMI and secrete soluble mediators leading to the fibroblastic proteins modification, thus participating to myocardial fibrosis.

The MEF2A transcription factor interactome in cardiomyocytes

Transcriptional regulators encoded by the Myocyte Enhancer Factor 2 (MEF2) gene family play a fundamental role in cardiac development, homeostasis and pathology. Previous studies indicate that MEF2A protein-protein interactions serve as a network hub in several cardiomyocyte cellular processes. Based on the idea that interactions with regulatory protein partners underly the diverse roles of MEF2A in cardiomyocyte gene expression, we undertook a systematic unbiased screen of the MEF2A protein interactome in primary cardiomyocytes using an affinity purification-based quantitative mass spectrometry approach. Bioinformatic processing of the MEF2A interactome revealed protein networks involved in the regulation of programmed cell death, inflammatory responses, actin dynamics and stress signaling in primary cardiomyocytes. Further biochemical and functional confirmation of specific protein-protein interactions documented a dynamic interaction between MEF2A and STAT3 proteins. Integration of transcriptome level data from MEF2A and STAT3-depleted cardiomyocytes reveals that the balance between MEF2A and STAT3 activity exerts a level of executive control over the inflammatory response and cardiomyocyte cell survival and experimentally ameliorates Phenylephrine induced cardiomyocyte hypertrophy. Lastly, we identified several MEF2A/STAT3 co-regulated genes, including the MMP9 gene. Herein, we document the cardiomyocyte MEF2A interactome, which furthers our understanding of protein networks involved in the hierarchical control of normal and pathophysiological cardiomyocyte gene expression in the mammalian heart.

Development of a Golgi-targeted superoxide anion fluorescent probe for elucidating protein GOLPH3 function in myocardial ischemia-reperfusion injury

Superoxide anion (O₂^•-) is an important reactive oxygen species (ROS) and participates in various physiological and pathological processes in the organism. The O₂^•- burst induced by ischemia-reperfusion (I/R) is associated with cardiovascular disease and promotes the cell apoptosis. In this work, a turn-on type Golgi-targeting fluorescent probe Gol-Cou-O₂^•- was rationally designed for sensitive and selective detection of O₂^•-. The minimum detection limit concentration for O₂^•- was about 3.9 × 10^-7 M in aqueous solution. Gol-Cou-O₂^•- showed excellent capacity of detecting exogenous and endogenous O₂^•- in living cells and zebrafish, and was also used to capture the up-regulated O₂^•- level during the duration of I/R process in cardiomyocytes. Golgi Phosphoprotein 3 (GOLPH3) is a potential Golgi stress marker protein and plays a key role in cells apoptosis during I/R. The fluorescence imaging and flow cytometry assay results indicated that silencing GOLPH3 through siRNA could give rise to the down-regulated O₂^•- level and alleviation of apoptosis in I/R myocardial cells. Thus, development of Gol-Cou-O₂^•- provides a diagnostic tool for myocardial oxidative stress injury and distinct insights on roles of GOLPH3 in myocardial I/R injury.

Cryptotanshinone Attenuated Pathological Cardiac Remodeling In Vivo and In Vitro Experiments

Objective

Cardiac remodeling has been demonstrated to be the early stage and common pathway for various types of cardiomyopathy, but no specific treatment has been suggested to prevent its development and progress. This study was aimed at assessing whether Cryptotanshinone (CTS) treatment could effectively attenuate cardiac remodeling in vivo and in vitro.

Methods

Aortic banding (AB) surgery was performed to establish a pressure-overload-induced mouse cardiac remodeling model. Echocardiography and pressure-volume proof were used to examine mouse cardiac function. Hematoxylin and eosin (HE) and Picro-Sirius Red (PSR) staining were used to assess cardiac remodeling in vivo. Mouse hearts were collected to analysis signaling pathway and cardiac remodeling markers, respectively. Furthermore, neonatal rat cardiomyocyte (NRCMs) and cardiac fibroblast (CF) were isolated to investigate the roles and mechanisms of CTS treatment in vitro.

Results

CTS administration significantly alleviated pressure-overload-induced mouse cardiac dysfunction, inhibited cardiac hypertrophy, and reduced cardiac fibrosis. Mechanically, CTS treatment significantly inhibited the STAT3 and TGF-β/SMAD3 signaling pathways. In vitro experiments, CTS treatment markedly inhibited AngII-induced cardiomyocyte hypertrophy and TGF-β-induced myofibroblast activation via inhibiting STAT3 phosphorylation and its nuclear translocation. Finally, CTS treatment could not protect against pressure overload-induced mouse cardiac remodeling after adenovirus-associated virus (AAV)9-mediated STAT3 overexpression in mouse heart.

Conclusion

CTS treatment might attenuate pathological cardiac remodeling via inhibiting STAT3-dependent pathway.

Melatonin Type 2 Receptor Activation Regulates Blue Light Exposure-Induced Mouse Corneal Epithelial Damage by Modulating Impaired Autophagy and Apoptosis

The MT1/2 receptors, members of the melatonin receptor, belong to G protein-coupled receptors and mainly regulate circadian rhythms and sleep in the brain. Previous studies have shown that in many other cells and tissues, such as HEK293T cells and the retina, MT1/2 receptors can be involved in mitochondrial homeostasis, antioxidant, and anti-inflammatory responses. In our study, we aimed to investigate the effects of blue light (BL) exposure on the expression of melatonin and its receptors in the mouse cornea and to evaluate their functional role in corneal epithelial damage. After exposing 8-week-old C57BL/6 mice to BL at 25 and 100 J/cm² twice a day for 14 days, a significant increase in the expression of 4-HNE and MT2 was observed in the cornea. MT2 antagonist-treated mice exposed to BL showed an increased expression of p62 and decreased expression of BAX and cleaved caspase 3 compared with mice exposed only to BL. In addition, MT2 antagonist-treated mice showed more enhanced MDA and corneal damage. In conclusion, BL exposure can induce MT2 expression in the mouse cornea. MT2 activation can modulate impaired autophagy and apoptosis by increasing the expression of BAX, an apoptosis activator, thereby regulating the progression of corneal epithelial damage induced by BL exposure.

Celastrol: A Promising Agent Fighting against Cardiovascular Diseases

Cardiovascular diseases (CVD) are leading causes of morbidity and mortality worldwide; therefore, seeking effective therapeutics to reduce the global burden of CVD has become increasingly urgent. Celastrol, a bioactive compound isolated from the roots of the plant Tripterygium wilfordii (TW), has been attracting increasing research attention in recent years, as it exerts cardiovascular treatment benefits targeting both CVD and their associated risk factors. Substantial evidence has revealed a protective role of celastrol against a broad spectrum of CVD including obesity, diabetes, atherosclerosis, cerebrovascular injury, calcific aortic valve disease and heart failure through complicated and interlinked mechanisms such as direct protection against cardiomyocyte hypertrophy and death, and indirect action on oxidation and inflammation. This review will mainly summarize the beneficial effects of celastrol against CVD, largely based on in vitro and in vivo preclinical studies, and the potential underlying mechanisms. We will also briefly discuss celastrol’s pharmacokinetic limitations, which hamper its further clinical applications, and prospective future directions.

Exercise-derived peptide protects against pathological cardiac remodeling

Background

Exercise training protects the heart against pathological cardiac remodeling and confers cardioprotection from heart failure. However, the underlying mechanism is still elusive.

Methods

An integrative analysis of multi-omics data of the skeletal muscle in response to exercise is performed to search for potential exerkine. Then, CCDC80tide is examined in humans after acute exercise. The role of CCDC80tide is assessed in a mouse model of hypertensive cardiac remodeling and in hypertension-mediated cell injury models. The transcriptomic analysis and immunoprecipitation assay are conducted to explore the mechanism.

Findings

The coiled-coil domain-containing protein 80 (CCDC80) is found strongly positively associated with exercise. Interestingly, exercise stimuli induce the secretion of C-terminal CCDC80 (referred as CCDC80tide hereafter) via EVs-encapsulated CCDC80tide into the circulation. Importantly, cardiac-specific expression of CCDC80tide protects against angiotensin II (Ang II)-induced cardiac hypertrophy and fibrosis in mice. In in vitro studies, the expression of CCDC80tide reduces Ang II-induced cardiomyocyte hypertrophy, cardiac microvascular endothelial cell (CMEC) inflammation, and mitigated vascular smooth muscle cell (VSMC) proliferation and collagen formation. To understand the cardioprotective effect of CCDC80tide, a transcriptomic analysis reveals a dramatic inhibition of the STAT3 (Signal transducer and activator of transcription 3) signaling pathway in CCDC80tide overexpressing cells. Mechanistically, CCDC80tide selectively interacts with the kinase-active form of JAK2 (Janus kinase 2) and consequently inhibits its kinase activity to phosphorylate and activate STAT3.

Interpretation

The results provide new insights into exercise-afforded cardioprotection in pathological cardiac remodeling and highlight the therapeutic potential of CCDC80tide in heart failure treatment.

Funding

This work was supported by the National Natural Science Foundation of China [Grant/Award Numbers: 81770428, 81830010, 82130012, 81900438, 82100447); Shanghai Science and Technology Committee [Grant/Award Numbers: 21S11903000, 19JC1415702]; Emerging and Advanced Technology Programs of Hospital Development Center of Shanghai [Grant/Award Number: SHDC12018129]; China Postdoctoral Science Foundation [2021M692108]; and China National Postdoctoral Program for Innovative Talents [BX20200211].

Upregulation of p67phox in response to ischemia/reperfusion is cardioprotective by increasing ZIP2 expression via STAT3

While the zinc transporter ZIP2 (Slc39a2) is upregulated via STAT3 as an adaptive response to protect the heart from ischemia/reperfusion (I/R) injury, the precise mechanism underlying its upregulation remains unclear. The purpose of this study was to investigate the role of NADPH oxidase (NOX) isoform NOX2-derived ROS in the regulation of ZIP2 expression, focusing on the role of the NOX2 cytosolic factor p67^phox. Mouse hearts or H9c2 cells were subjected to I/R. Protein expression was detected with Western blotting. Infarct size was measured with TTC staining. The cardiac-specific p67^phox conditional knockout mice (p67^phox cKO) were generated by adopting the CRISPR/Cas9 system. I/R-induced upregulation of STAT3 phosphorylation and ZIP2 expression was reversed by the ROS scavenger N-acetylcysteine (NAC) and the NOX inhibitor diphenyleneiodonium (DPI). p67^phox but not NOX2 expression was increased 30 min after the onset of reperfusion, and downregulation of p67^phox by siRNA or cKO invalidated I/R-induced upregulation of STAT3 phosphorylation and ZIP2 expression. Both NAC and DPI prevented upregulation of STAT3 phosphorylation and ZIP2 expression induced by overexpression of p67^phox, whereas the STAT3 inhibitor stattic abrogated upregulation ZIP2 expression, indicating that the increase of p67^phox at reperfusion is an upstream signaling event responsible for ZIP2 upregulation via STAT3. Experiments also showed that chelation of Zn²⁺ markedly enhanced p67^phox and ZIP2 expression as well as STAT3 phosphorylation, whereas supplementation of Zn²⁺ had the opposite effects, indicating that cardiac Zn²⁺ loss upon reperfusion triggers p67^phox upregulation. Furthermore, ischemic preconditioning (IPC) upregulated ZIP2 via p67^phox, and cKO of p67^phox aggravated cardiac injury after I/R, indicating that p67^phox upregulation is cardioprotective against I/R injury. In conclusion, an increase of p67^phox expression in response to Zn²⁺ is an intrinsic adaptive response to I/R and leads to cardioprotection against I/R by upregulating ZIP2 via STAT3.

Transcription Factors Involved in the Development and Prognosis of Cardiac Remodeling

To compensate increasing workload, heart must work harder with structural changes, indicated by increasing size and changing shape, causing cardiac remodeling. However, pathological and unlimited compensated cardiac remodeling will ultimately lead to decompensation and heart failure. In the past decade, numerous studies have explored many signaling pathways involved in cardiac remodeling, but the complete mechanism of cardiac remodeling is still unrecognized, which hinders effective treatment and drug development. As gene transcriptional regulators, transcription factors control multiple cellular activities and play a critical role in cardiac remodeling. This review summarizes the regulation of fetal gene reprogramming, energy metabolism, apoptosis, autophagy in cardiomyocytes and myofibroblast activation of cardiac fibroblasts by transcription factors, with an emphasis on their potential roles in the development and prognosis of cardiac remodeling.

Protective Effects of Curcumin in Cardiovascular Diseases—Impact on Oxidative Stress and Mitochondria

Cardiovascular diseases (CVDs) contribute to a large part of worldwide mortality. Similarly, two of the major risk factors for these diseases, aging and obesity, are also global problems. Aging, the gradual decline of body functions, is non-modifiable. Obesity, a modifiable risk factor for CVDs, also predisposes to type 2 diabetes mellitus (T2DM). Moreover, it affects not only the vasculature and the heart but also specific fat depots, which themselves have a major impact on the development and progression of CVDs. Common denominators of aging, obesity, and T2DM include oxidative stress, mitochondrial dysfunction, metabolic abnormalities such as altered lipid profiles and glucose metabolism, and inflammation. Several plant substances such as curcumin, the major active compound in turmeric root, have been used for a long time in traditional medicine and for the treatment of CVDs. Newer mechanistic, animal, and human studies provide evidence that curcumin has pleiotropic effects and attenuates numerous parameters which contribute to an increased risk for CVDs in aging as well as in obesity. Thus, curcumin as a nutraceutical could hold promise in the prevention of CVDs, but more standardized clinical trials are required to fully unravel its potential.

C188-9 reduces TGF-β1-induced fibroblast activation and alleviates ISO-induced cardiac fibrosis in mice

Cardiac fibrosis is the final event of heart failure and is associated with almost all forms of cardiovascular disease. Cardiac fibroblasts (CFs), a major cell type in the heart, are responsible for regulating normal myocardial function and maintaining extracellular matrix homeostasis in adverse myocardial remodeling. In this study, we found that C188‐9, a small‐molecule inhibitor of signal transducer and activator of transcription 3 (STAT3), exhibited an antifibrotic function, both in vitro and in vivo. C188‐9 decreased transforming growth factor‐β1‐induced CF activation and fibrotic gene expression. Moreover, C188‐9 treatment alleviated heart injury and cardiac fibrosis in an isoproterenol‐induced mouse model by suppressing STAT3 phosphorylation and activation. These findings may help us better understand the role of C188‐9 in cardiac fibrosis and facilitate the development of new treatments for cardiac fibrosis and other cardiovascular diseases.

Mechanism of Action of Nicotiflorin from Tricyrtis maculata in the Treatment of Acute Myocardial Infarction: From Network Pharmacology to Experimental Pharmacology

Purpose

Acute myocardial infarction (AMI) is a cardiovascular disease with a high fatality rate. In this study, we combined network pharmacology and experimental pharmacology and discovered the potential mechanism of action and the active ingredients of the lily, Tricyrtis maculata was discovered. The monomer compound with stronger activity was discovered through in vitro cell experiments.

Methods

Forty known compounds were isolated from T. maculata. Using TCMSP, Swiss Target Prediction, metaTarFisher, GeneCards and OMIM databases, targets of drug compositions and AMI-related genes were obtained, and the differential expression genes between AMI and normal tissues were extracted through the GEO database. Then, through an online mapping tool, the intersection genes were obtained to predict the possible effective components of T. maculata that can be used to treat AMI. The top five targets were selected for molecular docking via the protein–protein interaction (PPI) network to verify the binding activity between key compounds and target proteins. GO and KEGG enrichment analyses of the intersection genes were carried out with the program R to further screen key genes and effective compositions. On this basis, the compound with more optimal activity was screened and validated in vitro.

Results

In this study, 40 known monomer components were selected, and 1112 predicted genes, 1655 disease genes, 1425 differentially expressed genes, 1206 GO functions and 127 KEGG pathways were obtained. The results of molecular docking showed that the binding of MMP9 with drug components is stable. Through the comprehensive research of network pharmacology and experimental pharmacology, it was shown that T. maculata intervenes in the process of AMI through multicomponent, multitarget, and multichannel synergistic effects. It is speculated that the anti-AMI effect may be related to the regulation of the Akt/FoxO/BCl signaling pathway. Cellular experiments showed that nicotiflorin has satisfactory anti-inflammatory activity and endothelial protection and can reduce the release of nitric oxide (NO), an inflammatory medium after endothelial cell damage.

Conclusion

This study reveals the therapeutic effect and relative mechanism of extract of T. maculata extract on AMI. Analysis revealed that nicotiflorin from T. maculata is a compound with satisfactory anti-inflammatory activity and endothelial protection, which provides a new direction and treatment basis for further experimental exploration and clinical treatment.

Exogenous activation of toll-like receptor 5 signaling mitigates acetaminophen-induced hepatotoxicity in mice

Acetaminophen (APAP) poisoning is the most common cause of drug-induced acute liver injury (ALI). Our results showed that toll-like receptor 5 (TLR5) was abundantly expressed in hepatocytes and dramatically downregulated in the toxic mouse livers. Hence, we herein investigated the role of TLR5 signaling after APAP overdose. Mice were intraperitoneally (i.p.) injected with APAP to induce ALI, and then injected with flagellin at one hour after APAP administration. Flagellin attenuated APAP-induced ALI based on decreased histopathologic lesions, serum biochemical, oxidative stress, and inflammation. Furthermore, the protective effects of flagellin were abolished by TH1020 (a TLR5 antagonist) treatment. These results suggest that flagellin exerted protective effects on ALI via TLR5 activation. Mechanistically, flagellin injection promoted the translocation of nuclear factor erythroid 2-related factor 2 (Nrf2) to the nucleus in hepatocytes. Consistent with the in vivo results, flagellin increased the activation of Nrf2 in hepatocytes, resulting in decreased APAP toxicity. ML385, a selective inhibitor of Nrf2, abolished the flagellin-mediated hepatoprotective effects in damaged livers and hepatocytes. Additionally, the flagellin-induced Nrf2 translocation was dependent upon the activation of TLR5-JNK/p38 pathways. These findings suggest that TLR5 signaling-induced Nrf2 activation, at least partially, contributed to the protection against APAP-induced ALI by flagellin treatment.

Myocardial ischemia reperfusion injury is alleviated by curcumin-peptide hydrogel via upregulating autophagy and protecting mitochondrial function

Background

Ischemia-reperfusion injury (IRI) is an important factor limiting the success of cardiac reperfusion therapy. Curcumin has a significant cardioprotective effect against IRI, can inhibit ventricular remodeling induced by pressure load or MI, and improve cardiac function. However, the poor water solubility and low bioavailability of curcumin restrict its clinical application.

Methods

In this study, we prepared and evaluated a curcumin-hydrogel (cur-hydrogel) to reduce cardiomyocyte apoptosis and reactive oxygen species formation induced by hypoxia-reoxygenation injury, promote autophagy, and reduce mitochondrial damage by maintaining the phosphorylation of Cx43.

Results

Meanwhile, cur-hydrogel can restore cardiac function, inhibit myocardial collagen deposition and apoptosis, and activate JAK2/STAT3 pathway to alleviate myocardial ischemia-reperfusion injury in rats.

Conclusions

The purpose of this study is to elucidate the protective effects of cur-hydrogel on myocardial ischemia-reperfusion injury by regulating apoptosis, autophagy, and mitochondrial injury in vitro and in vivo, which lays a new theoretical and experimental foundation for the prevention and reduction of IRI.

Inhibition of HMGB1 Might Enhance the Protective Effect of Taxifolin in Cardiomyocytes via PI3K/AKT Signaling Pathway

Cardiovascular diseases (CVD) affect millions of people and spend a lot of medical costs around the world each year. Taxifolin is a natural anti-oxidative reagent obtained from multiple plants and exhibits a wide range of pharmacological effects. High mobility group box protein 1 (HMGB1) is expressed in multiple types of cells in the extracellular environment, regulating the pro-inflammatory process. Here, we detected the viability of cells using MTT assay, and the expression of each target protein was detected using western blotting analysis. The expression of each target mRNA was detected using the qPCR method, and the concentration of each cytokine in serum samples was detected using the ELISA method. In this study, we found that taxifolin could decrease the expression of hypoxia-inducible factor-1α (HIF-1α) while increasing the expression of endothelial nitric oxide synthase (eNOS), presented a protective role. Besides, taxifolin could also increase the expression of vascular endothelial growth factor-α (VEGF-α), transforming growth factor-β (TGF-β) and fibroblast growth factor21 (FGF21), resulting in viability rate increasing. And these effects were mediated by phosphatidylinositol 3-hydroxy kinase (PI3K)/AKT/mTOR signaling pathway; a similar trend was also observed in HMGB1 knockdown mice. We also found that inhibition of HMGB1 could enhance the cardioprotective effect of taxifolin and might be a new therapeutic strategy for cardiovascular disease.

Moderate Hydrogen Peroxide Postconditioning Ameliorates Ischemia/Reperfusion Injury in Cardiomyocytes via STAT3-Induced Calcium, ROS, and ATP Homeostasis

INTRODUCTION

Moderate hydrogen peroxide postconditioning (H2O2PoC) activates signal transducer and activator of transcription 3 (STAT3) to alleviate mitochondrial calcium overload during cardiac ischemia/reperfusion (I/R). However, the initial time window of STAT3-induced calcium hemostasis, the production of reactive oxygen species (ROS) and adenosine triphosphate (ATP) in H2O2PoC, and its regulated mechanism remain unknown. This study aimed to investigate H2O2PoC-induced homeostasis of calcium, ROS and ATP, and the role of STAT3 in the regulation.

METHODS

Isolated rat cardiomyocytes were exposed to H2O2PoC and Janus kinase 2 (JAK2)/STAT3 inhibitor AG490 during I/R. Ca2+ transients, cell contraction, intracellular calcium concentration, ROS production, ATP contents, phosphorylation of STAT3, gene and protein expression of manganese superoxide dismutase (MnSOD), metallothionein 1 (MT1) and metallothionein 2 (MT2), as well as activities of mitochondrial complex I and complex II were detected.

RESULTS

Moderate H2O2PoC improved post-ischemic Ca2+ transients and cell contraction recovery as well as alleviated cytosolic and mitochondrial calcium overload, which were abrogated by AG490 in rat cardiomyocytes. Moderate H2O2PoC increased ROS production and rate of ROS production at early reperfusion in rat I/R cardiomyocytes, and this phenomenon was also abrogated by AG490. Notably, the expression of phosphorylated nuclear STAT3; gene and protein expression of MnSOD, MT1, and MT2; and activities of mitochondrial complex I and complex II were upregulated by moderate H2O2PoC but downregulated by AG490.

CONCLUSION

These findings indicated that the cardioprotection of moderate H2O2PoC against cardiac I/R could be associated with activated STAT3 at early reperfusion to maintain calcium, ROS, and ATP homeostasis in rat cardiomyocytes.

Redox Regulation of STAT1 and STAT3 Signaling

STAT1 and STAT3 are nuclear transcription factors that regulate genes involved in cell cycle, cell survival and immune response. The cross-talk between these signaling pathways determines how cells integrate the environmental signals received ultimately translating them in transcriptional regulation of specific sets of genes. Despite being activated downstream of common cytokine and growth factors, STAT1 and STAT3 play essentially antagonistic roles and the disruption of their balance directs cells from survival to apoptotic cell death or from inflammatory to anti-inflammatory responses. Different mechanisms are proposed to explain this yin-yang relationship. Considering the redox aspect of STATs proteins, this review attempts to summarize the current knowledge of redox regulation of STAT1 and STAT3 signaling focusing the attention on the post-translational modifications that affect their activity.

STAT3/SOCS3 axis contributes to the outcome of salmonid whirling disease

There are differences in disease susceptibility to whirling disease (WD) among strains of rainbow trout. The North American strain Trout Lodge (TL) is highly susceptible, whereas the German Hofer (HO) strain is more resistant. The suppressor of cytokine signaling (SOCS) proteins are key in inhibiting cytokine signaling. Their role in modulating the immune response against whirling disease is not completely clear. This study aimed at investigating the transcriptional response of SOCS1 and SOCS3 genes to Myxobolus cerebralis along with that of several upstream regulators and immune response genes. M. cerebralis induced the expression of SOCS1, the IL-6-dependent SOCS3, the anti-inflammatory cytokine IL-10 and the Treg associated transcription factor FOXP3 in TL fish at multiple time points, which likely caused a restricted STAT1 and STAT3 activity affecting the Th17/Treg17 balance. The expression of SOCS1 and the IL-6-dependent SOCS3 was induced constraining the activation of STAT1 and STAT3 in TL fish, thereby causing Th17/Treg17 imbalance and leaving the fish unable to establish a protective immune response against M. cerebralis or control inflammatory reactions increasing susceptibility to WD. Conversely, in HO fish, the expression of SOCS1 and SOCS3 was restrained, whereas the expression of STAT1 and IL-23-mediated STAT3 was induced potentially enabling more controlled immune responses, accelerating parasite clearance and elevating resistance. The induced expression of STAT1 and IL-23-mediated STAT3 likely maintained a successful Th17/Treg17 balance and enabled fish to promote effective immune responses favouring resistance against WD. The results provide insights into the role of SOCS1 and SOCS3 in regulating the activation and magnitude of host immunity in rainbow trout, which may help us understand the mechanisms that underlie the variation in resistance to WD.

Interleukin-22 Directly Activates Myocardial STAT3 (Signal Transducer and Activator of Transcription-3) Signaling Pathway and Prevents Myocardial Ischemia Reperfusion Injury

BACKGROUND Interleukin (IL)-22, a member of the IL-10 cytokine family, is the only known cytokine that is secreted by immune cells but does not target immune cells; it mainly targets epithelial cells. In this study, we aimed to determine whether IL-22 administration could activate the myocardial STAT3 (signal transducer and activator of transcription-3) signaling pathway, and thus prevent myocardial injury, in a mouse model of ischemia reperfusion injury. METHODS AND RESULTS We evaluated the STAT3 activation after IL-22 injection by Western blot analysis and immunostaining for phosphorylated STAT3 in the heart and found that STAT3 activation in heart tissue rapidly peaked after IL-22 injection. Coimmunostaining of phosphorylated STAT3 and α-actinin revealed that STAT3 activation occurred in cardiomyocytes after IL-22 administration. In heart tissue from intact mice, real-time PCR demonstrated significant expression of IL-22 receptor subunit 1, and coimmunostaining of IL-22 receptor subunit 1 and α-actinin showed IL-22 receptor subunit 1 expression in cardiomyocytes. In cultured cardiomyocytes, IL-22 activated STAT3, and we detected IL-22 receptor subunit 1 expression. Overall, these results indicated that IL-22 directly activated the myocardial IL-22-receptor subunit 1-STAT3 signaling pathway. Following ischemia reperfusion, compared with PBS-treated mice, IL-22-treated mice exhibited a significantly reduced infarct size, significantly reduced myocardial apoptosis, and significantly enhanced phosphorylated STAT3 expression. Moreover, heart tissue from IL-22-treated mice exhibited a significantly reduced expression ratio of phosphorylated p53 to p53. CONCLUSIONS Our present findings suggest that IL-22 directly activated the myocardial STAT3 signaling pathway and acted as a cardioprotective cytokine to ameliorate acute myocardial infarction after ischemia reperfusion.

STAT3 for Cardiac Regenerative Medicine: Involvement in Stem Cell Biology, Pathophysiology, and Bioengineering

Heart disease is the most common cause of death in developed countries, but the medical treatments for heart failure remain limited. In this context, the development of cardiac regeneration therapy for severe heart failure is important. Owing to their unique characteristics, including multiple differentiation and infinitive self-renewal, pluripotent stem cells can be considered as a novel source for regenerative medicine. Janus kinase/signal transducer and activator of transcription 3 (JAK/STAT3) signaling plays critical roles in the induction, maintenance, and differentiation of pluripotent stem cells. In the heart, JAK/STAT3 signaling has diverse cellular functions, including myocardial differentiation, cell cycle re-entry of matured myocyte after injury, and anti-apoptosis in pathological conditions. Therefore, regulating STAT3 activity has great potential as a strategy of cardiac regeneration therapy. In this review, we summarize the current understanding of STAT3, focusing on stem cell biology and pathophysiology, as they contribute to cardiac regeneration therapy. We also introduce a recently reported therapeutic strategy for myocardial regeneration that uses engineered artificial receptors that trigger endogenous STAT3 signal activation.

Celastrol Attenuates Angiotensin II-Induced Cardiac Remodeling by Targeting STAT3

RATIONALE

Excessive Ang II (angiotensin II) levels lead to a profibrotic and hypertrophic milieu that produces deleterious remodeling and dysfunction in hypertension-associated heart failure. Agents that disrupt Ang II-induced cardiac dysfunction may have clinical utility in the treatment of hypertension-associated heart failure.

OBJECTIVE

We have examined the potential effect of celastrol-a bioactive compound derived from the Celastraceae family-on Ang II-induced cardiac dysfunction.

METHODS AND RESULTS

In rat primary cardiomyocytes and H9C2 (rat cardiomyocyte-like H9C2) cells, celastrol attenuates Ang II-induced cellular hypertrophy and fibrotic responses. Proteome microarrays, surface plasmon resonance, competitive binding assays, and molecular simulation were used to identify the molecular target of celastrol. Our data showed that celastrol directly binds to and inhibits STAT (signal transducer and activator of transcription)-3 phosphorylation and nuclear translocation. Functional tests demonstrated that the protection of celastrol is afforded through targeting STAT3. Overexpression of STAT3 dampens the effect of celastrol by partially rescuing STAT3 activity. Finally, we investigated the in vivo effect of celastrol treatment in mice challenged with Ang II and in the transverse aortic constriction model. We show that celastrol administration protected heart function in Ang II-challenged and transverse aortic constriction-challenged mice by inhibiting cardiac fibrosis and hypertrophy.

CONCLUSIONS

Our studies show that celastrol inhibits Ang II-induced cardiac dysfunction by inhibiting STAT3 activity.

Deletion of Rap1 protects against myocardial ischemia/reperfusion injury through suppressing cell apoptosis via activation of STAT3 signaling

Ischemic heart disease is a leading cause of morbidity and mortality. Repressor activator protein 1 (Rap1), an established telomere-associated protein, is a novel modulator of hypoxia-induced apoptosis. This study aimed to explore the potential direct role of Rap1 in myocardial ischemia/reperfusion injury (I/RI) and to determine the underlying molecular mechanism. In a mouse model of myocardial I/RI (30-min of left descending coronary artery ligation followed by 2-h reperfusion), Rap1 deficiency significantly reduced myocardial infarct size (IS) and improved cardiac systolic/diastolic function. This was associated with a reduction in apoptosis in the post-ischemic myocardium. In H9C2 and primary cardiomyocytes, Rap1 knockdown or knockout significantly suppressed hypoxia/reoxygenation (H/R)-induced cell injury and apoptosis through increasing the phosphorylation/activation of STAT3 at site Ser⁷²⁷ and translocation of STAT3 to the nucleus. We surmise this since Stattic (selective STAT3 inhibitor) pretreatment canceled the abovementioned protective effect. Furthermore, co-immunoprecipitation assay revealed a direct interaction between Rap1 and STAT3, but not JAK2, suggesting that the association of Rap1 with STAT3 may contribute to the reduced activity of STAT3 (Ser⁷²⁷ ) upon H/R stimulation. In conclusion, Rap1 deficiency protects the heart from ischemic damage through STAT3-dependent reduction of cardiomyocyte apoptosis, which may yield viable target for pharmacological intervention in ischemic heart disease.

The therapeutic effect of controlled reoxygenation on chronic hypoxia-associated brain injury

Cardiopulmonary bypass (CPB) is the most general technique applied in congenital heart disease (CHD). However, standard CPB poses a specific pathologic condition for patients during surgery: exposure to reoxygenation. When surgery is performed on cyanotic infants, standard CPB is usually initiated at a high concentration of oxygen without consideration of cytotoxic effects. Controlled reoxygenation is defined as using normoxic CPB with a pump primed to the PO2 (oxygen tension in the blood), which is matched to the patient's preoperative saturation. The aim of this study was to determine whether controlled reoxygenation could avoid standard reoxygenation injury and also to clarify the molecular signaling pathways during hypoxia. We successfully reproduced the abnormal brain observed in mice with chronic hypoxia during early postnatal development – equivalent to the third trimester in human. Mice were treated with standard reoxygenation and controlled reoxygenation after hypoxia for 24 h. We then assessed the brain tissue of these mice. In standard reoxygenation-treated hypoxia mice, the caspase-3-dependent neuronal apoptosis was enhanced by increasing concentration of oxygen. Interestingly, controlled reoxygenation inhibited neuron and glial cell apoptosis through suppressing cleavage of caspase-3 and PARP. We also found that controlled reoxygenation suppressed LCN2 expression and inflammatory cytokine (including TNF-α, IL-6, and CXCL10) production, in which the JAK2/STAT3 signaling pathway might participate. In conclusion, our findings propose the novel therapeutic potential of controlled reoxygenation on CPB during CHD.

Summary: Controlled reoxygenation may provide an effective therapeutic strategy for hypoxia-induced tissue injury via regulation of the JAK2/STAT3 signaling pathway. It will help make better informed clinical treatment decisions for cyanotic infants.

An Update on the Multifaceted Roles of STAT3 in the Heart

Signal transducer and activator of transcription 3 (STAT3) is a signaling molecule and transcription factor that plays important protective roles in the heart. The protection mediated by STAT3 is attributed to its genomic actions as a transcription factor and other non-genomic roles targeting mitochondrial function and autophagy. As a transcription factor, STAT3 upregulates genes that are anti-oxidative, anti-apoptotic, and pro-angiogenic, but suppresses anti-inflammatory and anti-fibrotic genes. Its suppressive effects on gene expression are achieved through competing with other transcription factors or cofactors. STAT3 is also linked to the modification of mRNA expression profiles in cardiac cells by inhibiting or inducing miRNA. In addition to these genomic roles, STAT3 is suggested to function protectively in mitochondria, where it regulates ROS production, in part by regulating the activities of the electron transport chain complexes, although our recent evidence calls this role into question. Nonetheless, STAT3 is a key player known to be activated in the cardioprotective ischemic conditioning protocols. Through these varied roles, STAT3 participates in various mechanisms that contribute to cardioprotection against different heart pathologies, including myocardial infarction, hypertrophy, diabetic cardiomyopathy, and peripartum cardiomyopathy. Understanding how STAT3 is involved in the protective mechanisms against these different cardiac pathologies could lead to novel therapeutic strategies to treat them.

Targeted inhibition of STAT3 as a potential treatment strategy for atherosclerosis

Atherosclerosis is the main pathological basis of ischemic cardiovascular and cerebrovascular diseases and has attracted more attention in recent years. Multiple studies have demonstrated that the signal transducer and activator of transcription 3 (STAT3) plays essential roles in the process of atherosclerosis. Moreover, aberrant STAT3 activation has been shown to contribute to the occurrence and development of atherosclerosis. Therefore, the study of STAT3 inhibitors has gradually become a focal research topic. In this review, we describe the crucial roles of STAT3 in endothelial cell dysfunction, macrophage polarization, inflammation, and immunity during atherosclerosis. STAT3 in mitochondria is mentioned as well. Then, we present a summary and classification of STAT3 inhibitors, which could offer potential treatment strategies for atherosclerosis. Furthermore, we enumerate some of the problems that have interfered with the development of mature therapies utilizing STAT3 inhibitors to treat atherosclerosis. Finally, we propose ideas that may help to solve these problems to some extent. Collectively, this review may be useful for developing future STAT3 inhibitor therapies for atherosclerosis.

Systems Network Genomic Analysis Reveals Cardioprotective Effect of MURC/Cavin-4 Deletion Against Ischemia/Reperfusion Injury

Background

Ischemia/reperfusion (I/R) injury is a critical issue in the development of treatment strategies for ischemic heart disease. MURC (muscle‐restricted coiled‐coil protein)/Cavin‐4 (caveolae‐associated protein 4), which is a component of caveolae, is involved in the pathophysiology of dilated cardiomyopathy and cardiac hypertrophy. However, the role of MURC in cardiac I/R injury remains unknown.

Methods and Results

The systems network genomic analysis based on PC‐corr network inference on microarray data between wild‐type and MURC knockout mouse hearts predicted a network of discriminating genes associated with reactive oxygen species. To demonstrate the prediction, we analyzed I/R‐injured mouse hearts. MURC deletion decreased infarct size and preserved heart contraction with reactive oxygen species–related molecule EGR1 (early growth response protein 1) and DDIT4 (DNA‐damage‐inducible transcript 4) suppression in I/R‐injured hearts. Because PC‐corr network inference integrated with a protein–protein interaction network prediction also showed that MURC is involved in the apoptotic pathway, we confirmed the upregulation of STAT3 (signal transducer and activator of transcription 3) and BCL2 (B‐cell lymphoma 2) and the inactivation of caspase 3 in I/R‐injured hearts of MURC knockout mice compared with those of wild‐type mice. STAT3 inhibitor canceled the cardioprotective effect of MURC deletion in I/R‐injured hearts. In cardiomyocytes exposed to hydrogen peroxide, MURC overexpression promoted apoptosis and MURC knockdown inhibited apoptosis. STAT3 inhibitor canceled the antiapoptotic effect of MURC knockdown in cardiomyocytes.

Conclusions

Our findings, obtained by prediction from systems network genomic analysis followed by experimental validation, suggested that MURC modulates cardiac I/R injury through the regulation of reactive oxygen species–induced cell death and STAT3‐meditated antiapoptosis. Functional inhibition of MURC may be effective in reducing cardiac I/R injury.

Angiotensin II Causes Biphasic STAT3 Activation Through TLR4 to Initiate Cardiac Remodeling

Evidence indicates that Ang II (angiotensin II) activates STAT3 (signal transducer and activator of transcription 3) in cardiomyocytes. However, the mechanisms underlying STAT3 activation and downstream responses are not fully known. In this study, we show that Ang II caused biphasic STAT3 activation in cardiomyocytes. A rapid and early activation was mediated by direct association between TLR4 (toll-like receptor-4) and STAT3. This early activation increased IL-6 (interleukin-6) production, which in turn, induced the second STAT3 activation through the IL-6/gp130 (glycoprotein 130)/JAK2 (Janus-family tyrosine kinases 2) pathway, resulting in unregulated expression of genes for cardiac remodeling. Moreover, STAT3 inhibition or TLR4 knockout in mice protected against Ang II-induced hypertrophy, fibrosis, and cardiac functional deficits. Thus, Ang II-induced STAT3 activation in cardiomyocytes was biphasic, providing a sequential induction of IL-6 and myocardial remodeling genes, respectively. This work supports a novel mechanism on STAT3 activation in Ang II-induced cardiac dysfunction and remodeling.

Effects of Cardiovascular Risk Factors on Cardiac STAT3

Nuclear, mitochondrial and cytoplasmic signal transducer and activator of transcription 3 (STAT3) regulates many cellular processes, e.g., the transcription or opening of mitochondrial permeability transition pore, and its activity depends on the phosphorylation of Tyr705 and/or Ser727 sites. In the heterogeneous network of cardiac cells, STAT3 promotes cardiac muscle differentiation, vascular element formation and extracellular matrix homeostasis. Overwhelming evidence suggests that STAT3 is beneficial for the heart, plays a role in the prevention of age-related and postpartum heart failure, protects the heart against cardiotoxic doxorubicin or ischaemia/reperfusion injury, and is involved in many cardioprotective strategies (e.g., ischaemic preconditioning, perconditioning, postconditioning, remote or pharmacological conditioning). Ischaemic heart disease is still the leading cause of death worldwide, and many cardiovascular risk factors contribute to the development of the disease. This review focuses on the effects of various cardiovascular risk factors (diabetes, aging, obesity, smoking, alcohol, depression, gender, comedications) on cardiac STAT3 under non-ischaemic baseline conditions, and in settings of ischaemia/reperfusion injury with or without cardioprotective strategies.

Analyses of changes in myocardial long non-coding RNA and mRNA profiles after severe hemorrhagic shock and resuscitation via RNA sequencing in a rat model

Background

Ischemia–reperfusion injury has been proven to induce organ dysfunction and death, although the mechanism is not fully understood. Long non-coding RNAs (lncRNAs) have drawn wide attention with their important roles in the gene expression of some biological processes and diseases, including myocardial ischemia–reperfusion (I/R) injury. In this paper, a total of 26 Sprague–Dawley (SD) rats were randomized into two groups: sham and ischemia–reperfusion (I/R) injury. Hemorrhagic shock was induced by removing 45% of the estimated total blood volume followed by reinfusion of shed blood. High-throughput RNA sequencing was used to analyze differentially expressed (DE) lncRNAs and messenger RNAs (mRNAs) in the heart tissue 4 h after reperfusion. Myocardial function was also evaluated.

Results

After resuscitation, the decline of myocardial function of shocked animals, expressed by cardiac output, ejection fraction, and myocardial performance index (MPI), was significant (p < 0.05). DE lncRNAs and mRNAs were identified by absolute value of fold change ≥ 2 and the false discovery rate ≤ 0.001. In rats from the I/R injury group, 851 lncRNAs and 1015 mRNAs were significantly up-regulated while 1533 lncRNAs and 1702 m RNAs were significantly down-regulated when compared to the sham group. Among the DE lncRNAs, we found 12 location-associated with some known apoptosis-related protein-coding genes which were up-regulated or down-regulated accordingly, including STAT3 and Il1r1. Real time PCR assays confirmed that the expression levels of five location-associated lncRNAs (NONRATT006032.2, NONRATT006033.2, NONRATT006034.2, NONRATT006035.2 and NONRATT029969.2) and their location-associated mRNAs (STAT3 and Il1r1) in the rats from the I/R injury group were all significantly up-regulated versus the sham group.

Conclusions

The DE lncRNAs (NONRATT006032.2, NONRATT006033.2, NONRATT006034.2 and NONRATT006035.2) could be compatible with their role in myocardial protection by stimulating their co-located gene (STAT3) after hemorrhagic shock and resuscitation. The final prognosis of I/R injury might be regulated by different genes, which is regarded as a complex network.

Electronic supplementary material

The online version of this article (10.1186/s12867-018-0113-8) contains supplementary material, which is available to authorized users.

Conditioning-induced cardioprotection: Aging as a confounding factor

The aging process induces a plethora of changes in the body including alterations in hormonal regulation and metabolism in various organs including the heart. Aging is associated with marked increase in the vulnerability of the heart to ischemia-reperfusion injury. Furthermore, it significantly hampers the development of adaptive response to various forms of conditioning stimuli (pre/post/remote conditioning). Aging significantly impairs the activation of signaling pathways that mediate preconditioning-induced cardioprotection. It possibly impairs the uptake and release of adenosine, decreases the number of adenosine transporter sites and down-regulates the transcription of adenosine receptors in the myocardium to attenuate adenosine-mediated cardioprotection. Furthermore, aging decreases the expression of peroxisome proliferator-activated receptor gamma co-activator 1-alpha (PGC-1α) and subsequent transcription of catalase enzyme which subsequently increases the oxidative stress and decreases the responsiveness to preconditioning stimuli in the senescent diabetic hearts. In addition, in the aged rat hearts, the conditioning stimulus fails to phosphorylate Akt kinase that is required for mediating cardioprotective signaling in the heart. Moreover, aging increases the concentration of Na⁺ and K⁺, connexin expression and caveolin abundance in the myocardium and increases the susceptibility to ischemia-reperfusion injury. In addition, aging also reduces the responsiveness to conditioning stimuli possibly due to reduced kinase signaling and reduced STAT-3 phosphorylation. However, aging is associated with an increase in MKP-1 phosphorylation, which dephosphorylates (deactivates) mitogen activated protein kinase that is involved in cardioprotective signaling. The present review describes aging as one of the major confounding factors in attenuating remote ischemic preconditioning-induced cardioprotection along with the possible mechanisms.

STAT3 and apoptosis challenges in cancer

Several studies have processed conceivable evidence for the vital role of Signal Transducer and Activator of Transcription 3 (STAT3) in cancer transformation and carcinogenesis. Therefore, one of the important factors in formation of cancer is STAT3 and for design of novel anticancer drugs is a suitable target. On the other hand, apoptosis pathway has a critical role in the cancers pathogenesis. Generally, increasing developments have been existed to expression, production, phosphorylation or activation of STAT3 in the effective or responsible cells of most of the cancers. In return, apoptosis process in this cells have been suffered inhibition, decrease in expression, produce or activation in some related factors which lead to debilitation or inhibition of the process. Further understanding of the STAT3 related signaling and apoptosis pathway can lead to the invention of novel approaches for therapies in unstudied disease. In this manuscript, review and highlight recent knowledge of the STAT3 pathway and its connection with apoptosis process in cancers and discuss STAT3-targeting agents to therapeutic developments.

Vagal stimulation mimics preconditioning and postconditioning of ischemic myocardium in mice by activating different protection mechanisms

Vagal stimulation (VS) during myocardial ischemia and reperfusion has beneficial effects. However, it is not known whether short-term VS applied before ischemia or at the onset of reperfusion protects the ischemic myocardium. This study was designed to determine whether short-term VS applied before ischemia or at the onset of reperfusion reduces myocardial infarct size (IS), mimicking classic preconditioning and postconditioning. A second objective was to study the participation of muscarinic and nicotinic receptors in the protection of both preischemic and reperfusion stimulation. FVB mice were subjected to 30 min of regional myocardial ischemia followed by 2 h of reperfusion without VS, with 10-min preischemic VS (pVS), or with VS during the first 10 min of reperfusion (rVS). pVS reduced IS, and this effect was abolished by atropine and wortmannin. rVS also reduced IS in a similar manner, and this effect was abolished by the α₇-nicotinic acetylcholine receptor blocker methyllycaconitine. pVS increased Akt and glycogen synthase kinase (GSK)-3β phosphorylation. No changes in Akt and GSK-3β phosphorylation were observed in rVS. Stimulation-mediated IS protection was abolished with the JAK2 blocker AG490. rVS did not modify IL-6 and IL-10 levels in the plasma or myocardium. Splenic denervation and splenectomy did not abolish the protective effect of rVS. In conclusion, pVS and rVS reduced IS by different mechanisms: pVS activated the Akt/GSK-3β muscarinic pathway, whereas rVS activated α₇-nicotinic acetylcholine receptors and JAK2, independently of the cholinergic anti-inflammatory pathway. NEW & NOTEWORTHY Our data suggest, for the first time, that vagal stimulation applied briefly either before ischemia or at the beginning of reperfusion mimics classic preconditioning and postconditioning and reduces myocardial infarction, activating different mechanisms. We also infer an important role of α₇-nicotinic receptors for myocardial protection independent of the cholinergic anti-inflammatory pathway.

S-glutathionylation exerts opposing roles in the regulation of STAT1 and STAT3 signaling in reactive microglia

STAT1 and STAT3 are two transcription factors involved in a lot of cellular functions such as immune response, proliferation, apoptosis, and cell survival. A number of literature evidences described a yin-yang relationship between activation of STAT1 and STAT3 in neurodegenerative disorders where STAT1 exerts a pro-apoptotic effect whereas STAT3 shows neuroprotective properties through the inhibition of apoptosis. Although the role of oxidative-stress in the pathogenesis of neurodegeneration is clearly described, its influence in the regulation of these pathways is poorly understood. Herein, we demonstrate that H₂O₂ rapidly induces phosphorylation of STAT1 whereas it is not able to influence phosphorylation of STAT3 in mouse microglia BV2 cells. The analysis of the molecular mechanism of STATs signaling reveals that H₂O₂ induces S-glutathionylation of both STAT1 and STAT3. The same post-translational event exerts an opposing role in the regulation of STAT1 and STAT3 signaling. These data not only confirm redox sensibility of STAT3 signaling but also reveal for the first time that STAT1 is susceptible to redox regulation. A deep study of the molecular mechanism of STAT1 redox regulation, identifies Cys324 and Cys492 as the main targets of S-glutathionylation and confirms that S-glutathionylation does not impair JAK2 mediated STAT1 tyrosine phosphorylation. These results demonstrate that both phosphorylation and glutathionylation contribute to activation of STAT1 during oxidative stress and underline that the same post-translation event exerts an opposing role in the regulation of STAT1 and STAT3 signaling in microglia cells.

Optimized induction of beta common receptor enhances the neuroprotective function of erythropoietin in spinal cord ischemic injury

BACKGROUND

Paraplegia remains the most feared complication of complex thoracoabdominal aortic intervention. Although erythropoietin (EPO) has demonstrated neuroprotective effects in spinal cord ischemia, it does not work until expression of the beta common receptor subunit of the EPO receptor (βcR) is induced by ischemia. We hypothesized that the βcR can be induced by diazoxide (DZ), amplifying the neuroprotective effects of EPO in spinal cord ischemia-reperfusion injury.

METHODS

For the DZ time trial, adult male C57/BL6 mice received DZ (20 mg/kg) by oral gavage. Spinal cords were harvested after 0, 12, 24, 36, and 48 hours of administration. To evaluate optimal dosing, DZ was administered at 0, 5, 10, 20, and 40 mg/kg. The expression of βcR was assessed by Western blot analysis. Five groups were studied: PBS (pretreatment)+PBS (immediately before), PBS+EPO, DZ+PBS, DZ+EPO, and sham (without cross-clamping). Spinal cord ischemia was induced by 4 minutes of thoracic aortic cross-clamping. Functional scoring (Basso Mouse Score) was done at 12-hour intervals for 48 hours, and spinal cords were harvested for histological analysis.

RESULTS

Western blot analysis demonstrated that optimal βcR up-regulation occurred at 36 hours after DZ administration, and the optimal DZ dosage for βcR induction was 20 mg/kg. Motor function at 48 hours after treatment was significantly better preserved in the DZ+EPO group compared with all other groups, and was significantly better preserved in the DZ only and EPO only groups compared with control (PBS+PBS).

CONCLUSIONS

Pharmacologic up-regulation of βcR with DZ can increase the efficacy of EPO in preventing spinal cord ischemia and reperfusion injury. Improved understanding of this synergetic mechanism may serve to further prevent ischemic complications for high-risk aortic intervention.

Cardioprotective effect of ghrelin against myocardial infarction-induced left ventricular injury via inhibition of SOCS3 and activation of JAK2/STAT3 signaling

The molecular mechanisms through which ghrelin exerts its cardioprotective effects during cardiac remodeling post-myocardial infarction (MI) are poorly understood. The aim of this study was to investigate whether the cardioprotection mechanisms are mediated by modulation of JAK/STAT signaling and what triggers this modulation. Rats were divided into six groups (n = 12/group): control, sham, sham + ghrelin (100 µg/kg, s.c., daily, starting 1 day post-MI), MI, MI+ ghrelin, and MI+ ghrelin+ AG490, a potent JAK2 inhibitor (5 mg/kg, i.p., daily). All treatments were administered for 3 weeks. Administration of ghrelin to MI rats improved left ventricle (LV) architecture and restored cardiac contraction. In remote non-infarcted areas of MI rats, ghrelin reduced cardiac inflammation and lipid peroxidation and enhanced antioxidant enzymatic activity. In addition, independent of the growth factor/insulin growth factor-1 (GF/IGF-1) axis, ghrelin significantly increased the phosphorylation of JAK2 and Tyr702 and Ser727 residues of STAT3 and inhibited the phosphorylation of JAK1 and Tyr701 and Ser727 residues of STAT1, simultaneously increasing the expression of BCL-2 and decreasing in the expression of BAX, cleaved CASP3, and FAS. This effect coincided with decreased expression of SOCS3. All these beneficial effects of ghrelin, except its inhibitory action on IL-6 expression, were partially and significantly abolished by the co-administration of AG490. In conclusion, the cardioprotective effect of ghrelin against MI-induced LV injury is exerted via activation of JAK2/STAT3 signaling and inhibition of STAT1 signaling. These effects were independent of the GF/IGF-1 axis and could be partially mediated via inhibition of cardiac IL-6.

Immune response of olive flounder (Paralichthys olivaceus) infected with the myxosporean parasite Kudoa septempunctata

This study evaluated the pathophysiological, biochemical, and immunological status of olive flounder (Paralichthys olivaceus) infected with the myxosporean parasite Kudoa septempunctata. Flounder fish collected from Kudoa-infected and uninfected farms were confirmed by microscopic and TaqMan probe-based quantitative PCR screening. Morphological, biochemical, histological, and immune gene expression analyses were performed on uninfected and infected hosts to assess the effect of K. septempunctata. Histological studies confirmed the presence of Kudoa myxospores in the trunk muscles of infected flounder fish. Serum biochemical parameters, including the levels of myeloperoxidase activity, superoxide dismutase activity, alanine aminotransferase, alkaline phosphatase, amylase, bilirubin, total protein, cholesterol, calcium, potassium, sodium, phosphorus, glucose, and galactose, were found to exhibit no significant variations (p > 0.05) between uninfected and infected flounder fish. However, immune-related genes such as Mx, lysozyme, signal transducer and activator of transcription 1, interferon-γ, interferon regulatory factor, and tumour necrosis factor showed significantly elevated expression (p < 0.05) in the trunk muscles of infected flounder fish while no significant differences were noted in uninfected fish trunk muscle and head-kidney of infected and uninfected flounder fish.

Adult murine cardiomyocytes exhibit regenerative activity with cell cycle reentry through STAT3 in the healing process of myocarditis

Mammalian cardiomyocytes substantially lose proliferative capacity immediately after birth, limiting adult heart regeneration after injury. However, clinical myocarditis appears to be self-limiting with tissue-reparative properties. Here, we investigated the molecular mechanisms underlying the recovery from myocarditis with regard to cardiomyocyte proliferation using an experimental autoimmune myocarditis (EAM) model. Three weeks after EAM induction (EAM3w), cardiac tissue displayed infiltration of inflammatory cells with cardiomyocyte apoptosis. However, by EAM5w, the myocardial damage was remarkably attenuated, associated with an increase in cardiomyocytes that were positively stained with cell cycle markers at EAM3w. Cardiomyocyte fate mapping study revealed that the proliferating cardiomyocytes primarily derived from pre-existing cardiomyocytes. Signal transducer and activator of transcription 3 (STAT3) was robustly activated in cardiomyocytes during inflammation, accompanied by induction of interleukin-6 family cytokines. Cardiomyocyte-specific ablation of STAT3 gene suppressed the frequency of cycling cardiomyocytes in the recovery period without influencing inflammatory status, resulting in impaired tissue repair and cardiac dysfunction. Finally, microarray analysis revealed that the expression of regeneration-related genes, metallothioneins and clusterin, in cardiomyocytes was decreased by STAT3 gene deletion. These data show that adult mammalian cardiomyocytes restore regenerative capacity with cell cycle reentry through STAT3 as the heart recovers from myocarditis-induced cardiac damage.

Glutamine Improves Myocardial Function following Ischemia-Reperfusion Injury

Myocardial ischemia-reperfusion injury is common during cardiac procedures. Glutamine may protect the myocardium by preserving metabolic substrates. Glutamine (0.52 g·kg−1) or Ringer's lactate solution (control group) was administered intraperitoneally to 63 Sprague-Dawley rats at 4 or 18 hours prior to experimental ischemia and reperfusion. The hearts were excised and perfused on an isolated working heart model, exposed to global ischemia for 15 min and reperfusion for 1 hour. Left atrial pressure, mean aortic pressure, cardiac flow, coronary flow, and aortic output were measured 15 min before ischemia and every 15 min during reperfusion. There was significantly better cardiac output in the glutamine pretreated groups. Pretreatment at 4 hours before the experiment was superior to pretreatment at 18 hours, with better maintenance of cardiac output and coronary flow. The enhanced protective effect of pretreatment at 4 hours highlights the importance of timing, and suggests a potential clinical benefit.

Metallothioneins 1 and 2 Modulate Inflammation and Support Remodeling in Ischemic Cardiomyopathy in Mice

Aims. Repetitive brief ischemia and reperfusion (I/R) is associated with left ventricular dysfunction during development of ischemic cardiomyopathy. We investigated the role of zinc-donor proteins metallothionein MT1 and MT2 in a closed-chest murine model of I/R. Methods. Daily 15-minute LAD-occlusion was performed for 1, 3, and 7 days in SV129 (WT)- and MT1/2 knockout (MT(-/-))-mice (n = 8-10/group). Hearts were examined with M-mode echocardiography and processed for histological and mRNA studies. Results. Expression of MT1/2 mRNA was transiently induced during repetitive I/R in WT-mice, accompanied by a transient inflammation, leading to interstitial fibrosis with left ventricular dysfunction without infarction. In contrast, MT(-/-)-hearts presented with enhanced apoptosis and small infarctions leading to impaired global and regional pump function. Molecular analysis revealed maladaptation of myosin heavy chain isoforms and antioxidative enzymes in MT1/2(-/-)-hearts. Despite their postponed chemokine induction we found a higher total neutrophil density and macrophage infiltration in small infarctions in MT(-/-)-hearts. Subsequently, higher expression of osteopontin 1 and tenascin C was associated with increased myofibroblast density resulting in predominately nonreversible fibrosis and adverse remodeling in MT1/2(-/-)-hearts. Conclusion. Cardioprotective effects of MT1/2 seem to be exerted via modulation of contractile elements, antioxidative enzymes, inflammatory response, and myocardial remodeling.

Understanding STAT3 signaling in cardiac ischemia

Cardiovascular disease is the leading cause of death worldwide. It remains one of the greatest challenges to global health and will continue to dominate mortality trends in the future. Acute myocardial infarction results in 7.4 million deaths globally per annum. Current management strategies are centered on restoration of coronary blood flow via percutaneous coronary intervention, coronary artery bypass grafting and administration of anti-platelet agents. Such myocardial reperfusion accounts for 40-50 % of the final infarct size in most cases. Signaling transducer and activator of transcription 3 (STAT3) has been shown to have cardioprotective effects via canonical and non-canonical activation and modulation of mitochondrial and transcriptional responses. A significant body of in vitro and in vivo evidence suggests that activation of the STAT3 signal transduction pathway results in a cardio protective response to ischemia and attempts have been made to modulate this with therapeutic effect. Not only is STAT3 important for cardiomyocyte function, but it also modulates the cardiac microenvironment and communicates with cardiac fibroblasts. To this end, we here review the current evidence supporting the manipulation of STAT3 for therapeutic benefit in cardiac ischemia and identify areas for future research.