Activation of signal transducer and activator of transcription 3 protects cardiomyocytes from hypoxia/reoxygenation-induced oxidative stress through the upregulation of manganese superoxide dismutase

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.

Are peptidomimetics the compounds of choice for developing new modulators of the JAK-STAT pathway?

Protein-protein interactions (PPIs) play critical roles in a wide range of biological processes including the dysregulation of cellular pathways leading to the loss of cell function, which in turn leads to diseases. The dysfunction of several signaling pathways is linked to the insurgence of pathological processes such as inflammation, cancer development and neurodegeneration. Thus, there is an urgent need for novel chemical modulators of dysregulated PPIs to drive progress in targeted therapies. Several PPIs have been targeted by bioactive compounds, and, often, to properly cover interacting protein regions and improve the biological activities of modulators, a particular focus concerns the employment of macrocycles as proteomimetics. Indeed, for their physicochemical properties, they occupy an intermediate space between small organic molecules and macromolecular proteins and are prominent in the drug discovery process. Peptide macrocycles can modulate fundamental biological mechanisms and here we will focus on peptidomimetics active on the Janus kinase/signal transducers and activators of transcription (JAK-STAT) pathways.

Loganin protects against myocardial ischemia-reperfusion injury by modulating oxidative stress and cellular apoptosis via activation of JAK2/STAT3 signaling

BACKGROUND

Myocardial ischemia-reperfusion injury (MIRI) is a pathological process that follows immediate revascularization of myocardial infarction and is characterized by exacerbation of cardiac injury. Loganin, a monoterpene iridoid glycoside derived from Cornus officinalis Sieb. Et Zucc, can exert cardioprotective effects in cardiac hypertrophy and atherosclerosis. However, its role in ischemic heart disease remains largely unknown.

METHODS

Considering that Janus kinase 2 (JAK2)/ signal transducer and activator of transcription 3 (STAT3) has a protective effect on the heart, we developed a mouse model of MIRI to investigate the potential role of this pathway in loganin-induced cardioprotection.

RESULTS

Our results showed that treatment with loganin (20 mg/kg) prevented the enlargement of myocardial infarction, myocyte destruction, serum markers of cardiac injury, and deterioration of cardiac function induced by MIRI. Myocardium subjected to I/R treatment exhibited higher levels of oxidative stress, as indicated by an increase in malondialdehyde (MDA) and dihydroethidium (DHE) density and a decrease in total antioxidant capacity (T-AOC), glutathione (GSH), and superoxide dismutase (SOD), whereas treatment with loganin showed significant attenuation of I/R-induced oxidative stress. Loganin treatment also increased the expression of anti-apoptotic Bcl-2 and reduced the expression of caspase-3/9, Bax, and the number of TUNEL-positive cells in ischemic cardiac tissue. Moreover, treatment with loganin triggered JAK2/STAT3 phosphorylation, and AG490, a JAK2/STAT3 inhibitor, partially abrogated the cardioprotective effects of loganin, indicating the essential role of JAK2/STAT3 signaling in the cardioprotective effects of loganin.

CONCLUSIONS

Our data demonstrate that loganin protects the heart from I/R injury by inhibiting I/R-induced oxidative stress and cellular apoptosis via activation of JAK2/STAT3 signaling.

Integration of machine learning to identify diagnostic genes in leukocytes for acute myocardial infarction patients

BACKGROUND

Acute myocardial infarction (AMI) has two clinical characteristics: high missed diagnosis and dysfunction of leukocytes. Transcriptional RNA on leukocytes is closely related to the course evolution of AMI patients. We hypothesized that transcriptional RNA in leukocytes might provide potential diagnostic value for AMI. Integration machine learning (IML) was first used to explore AMI discrimination genes. The following clinical study was performed to validate the results.

METHODS

A total of four AMI microarrays (derived from the Gene Expression Omnibus) were included in bioanalysis (220 sample size). Then, the clinical validation was finished with 20 AMI and 20 stable coronary artery disease patients (SCAD). At a ratio of 5:2, GSE59867 was included in the training set, while GSE60993, GSE62646, and GSE48060 were included in the testing set. IML was explicitly proposed in this research, which is composed of six machine learning algorithms, including support vector machine (SVM), neural network (NN), random forest (RF), gradient boosting machine (GBM), decision trees (DT), and least absolute shrinkage and selection operator (LASSO). IML had two functions in this research: filtered optimized variables and predicted the categorized value. Finally, The RNA of the recruited patients was analyzed to verify the results of IML.

RESULTS

Thirty-nine differentially expressed genes (DEGs) were identified between controls and AMI individuals from the training sets. Among the thirty-nine DEGs, IML was used to process the predicted classification model and identify potential candidate genes with overall normalized weights > 1. Finally, two genes (AQP9 and SOCS3) show their diagnosis value with the area under the curve (AUC) > 0.9 in both the training and testing sets. The clinical study verified the significance of AQP9 and SOCS3. Notably, more stenotic coronary arteries or severe Killip classification indicated higher levels of these two genes, especially SOCS3. These two genes correlated with two immune cell types, monocytes and neutrophils.

CONCLUSION

AQP9 and SOCS3 in leukocytes may be conducive to identifying AMI patients with SCAD patients. AQP9 and SOCS3 are closely associated with monocytes and neutrophils, which might contribute to advancing AMI diagnosis and shed light on novel genetic markers. Multiple clinical characteristics, multicenter, and large-sample relevant trials are still needed to confirm its clinical value.

Role of Interleukin-6 Family Cytokines in Organ Fibrosis

Background

Organ fibrosis remains an important cause of high incidence rate and mortality worldwide. The prominent role of interleukin-6 (IL-6) family members represented by IL-6 in inflammation has been extensively studied, and drugs targeting IL-6 have been used clinically. Because of the close relationship between inflammation and fibrosis, researches on the role of IL-6 family members in organ fibrosis are also gradually emerging.

Summary

In this review, we systematically reviewed the role of IL-6 family members in fibrosis and their possible mechanisms. We listed the role of IL-6 family members in organ fibrosis and drew two diagrams to illustrate the downstream signal transductions of IL-6 family members. We also summarized the effect of some IL-6 family members' antagonists in a table.

Key Messages

Fibrosis contributes to organ structure damage, organ dysfunction, and eventually organ failure. Although IL-6 family cytokines have similar downstream signal pathways, different members play various roles in an organ-specific manner which might be partly due to their different target cell populations. The pathogenic role of individual member in various diseases needs to be deciphered carefully.

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.

Hydrogen peroxide preconditioning is of dual role in cardiac ischemia/reperfusion

Moderate reactive oxygen species (ROS) at reperfusion would trigger cardioprotection and various antioxidants for pharmacological preconditioning failed to achieve cardioprotection. The causes for different roles of preischemic ROS during cardiac ischemia/reperfusion (I/R) require reevaluation. We investigated the precise role of ROS and its working model in this study. Different doses of hydrogen peroxide (H₂O₂, the most stable form of ROS) were added 5 min before ischemia using isolated perfused rat hearts, only moderate-dose H₂O₂ preconditioning (H₂O₂PC) achieved contractile recovery, whereas the low dose and high dose led to injury. Similar results were observed in isolated rat cardiomyocytes on cytosolic free Ca²⁺ concentration ([Ca²⁺]_c) overload, ROS production, the recovery of Ca²⁺ transient, and cell shortening. Based on the data mentioned above, we set up a mathematics model to describe the effects of H₂O₂PC with the fitting curve by the percentage of recovery of heart function and Ca²⁺ transient in I/R. Besides, we used the two models to define the initial thresholds of H₂O₂PC achieving cardioprotection. We also detected the expression of redox enzymes and Ca²⁺ signaling toolkits to explain the mathematics models of H₂O₂PC in a biological way. The expression of tyrosine 705 phosphorylation of STAT3, Nuclear factor E2-related factor 2, manganese superoxide dismutase, phospholamban, catalase, ryanodine receptors, and sarcoendoplasmic reticulum calcium ATPase 2 were similar with the control I/R and low-dose H₂O₂PC but were increased in the moderate H₂O₂PC and decreased in the high-dose H₂O₂PC. Thus, we concluded that preischemic ROS are of dual role in cardiac I/R.

Prolactin Inhibition in Peripartum Cardiomyopathy: Systematic Review and Meta-analysis

Heart failure (HF) is one of the leading causes of maternal mortality and morbidity in the United States. Peripartum cardiomyopathy (PPCM) constitutes up to 70% of all HF in pregnancy. Cardiac angiogenic imbalance caused by cleaved 16kDa prolactin has been hypothesized to contribute to the development of PPCM, fueling investigation of prolactin inhibitors for the management of PPCM. We conducted a systematic review and meta-analysis to assess the impact of prolactin inhibition on left ventricular (LV) function and mortality in patients with PPCM. We included English language articles from PubMed and EMBASE published upto March 2022. We pooled the mean difference (MD) for left ventricular ejection fraction (LVEF) at follow-up, odds ratio (OR) for LV recovery and risk ratio (RR) for all-cause mortality using random-effects meta-analysis. Among 548 studies screened, 10 studies (3 randomized control trials (RCTs), 2 retrospective and 5 prospective cohorts) were included in the systematic review. Patients in the Bromocriptine + standard guideline directed medical therapy (GDMT) group had higher LVEF% (pMD 12.56 (95% CI 5.84-19.28, I2=0%) from two cohorts and pMD 14.25 (95% CI 0.61-27.89, I2=88%) from two RCTs) at follow-up compared to standard GDMT alone group. Bromocriptine group also had higher odds of LV recovery (pOR 3.55 (95% CI 1.39-9.1, I2=62)). We did not find any difference in all-cause mortality between the groups. Our analysis demonstrates that the addition of Bromocriptine to standard GDMT was associated with a significant improvement in LVEF% and greater odds of LV recovery, without significant reduction in all-cause mortality.

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.

Immuno-activated mesenchymal stem cell living electrospun nanofibers for promoting diabetic wound repair

Diabetic wound is the leading cause of non-traumatic amputations in which oxidative stress and chronic inflammation are main factors affecting wound healing. Although mesenchymal stem cells (MSCs) as living materials can promote skin regeneration, they are still vulnerable to oxidative stress which limits their clinical applications. Herein, we have prepared (polylactic-co-glycolic acid) (PLGA) nanofibers electrospun with LPS/IFN-γ activated macrophage cell membrane. After defining physicochemical properties of the nanofibers modified by LPS/IFN-γ activated mouse RAW264.7 cell derived membrane (RCM-fibers), we demonstrated that the RCM-fibers improved BMMSC proliferation and keratinocyte migration upon oxidative stress in vitro. Moreover, bone marrow derived MSCs (BMMSCs)-loaded RCM-fibers (RCM-fiber-BMMSCs) accelerated wound closure accompanied by rapid re-epithelialization, collagen remodeling, antioxidant stress and angiogenesis in experimental diabetic wound healing in vivo. Transcriptome analysis revealed the upregulation of genes related to wound healing in BMMSCs when co-cultured with the RCM-fibers. Enhanced healing capacity of RCM-fiber-BMMSCs living material was partially mediated through CD200-CD200R interaction. Similarly, LPS/IFN-γ activated THP-1 cell membrane coated nanofibers (TCM-fibers) exhibited similar improvement of human BMMSCs (hBMMSCs) on diabetic wound healing in vivo. Our results thus demonstrate that LPS/IFN-γ activated macrophage cell membrane-modified nanofibers can in situ immunostimulate the biofunctions of BMMSCs, making this novel living material promising in wound repair of human diabetes.

A systematic review on the role of MSC-derived exosomal miRNAs in the treatment of heart failure

BACKGROUND

This systematic review summarizes results of studies that evaluated the expression of microRNAs (miRs) in pre-diabetes or type 2 diabetes.

METHODS

The information was obtained in PubMed, EMBL-EBI, Wanfang, Trip Database, Lilacs, CINAHL and Google. A qualitative synthesis of the results was performed and miRs frequency was graphically. From 1880 we identified studies, only 53 fulfilled the inclusion criteria. The 53 studies analyzed miRs in T2D; and of them, thirteen also described data in pre-diabetes.

RESULTS

In diabetics, 122 miRs were reported and 35 miRs for pre-diabetics. However, we identified that 5 miRs (-122-5p, 144-3p, 210, 375, -126b) were reported more often in diabetics, and 4 (144-3p, -192, 29a and -30d) in pre-diabetics.

CONCLUSIONS

Circulating miRs could be used as biomarkers of type 2 diabetes. However, it is necessary to validate these microRNAs in prospective and multi-center studies, where different population subgroups, considering the age, gender, and risk factors.

Concomitant Activation of OSM and LIF Receptor by a Dual-Specific hlOSM Variant Confers Cardioprotection after Myocardial Infarction in Mice

Oncostatin M (OSM) and leukemia inhibitory factor (LIF) signaling protects the heart after myocardial infarction (MI). In mice, oncostatin M receptor (OSMR) and leukemia inhibitory factor receptor (LIFR) are selectively activated by the respective cognate ligands while OSM activates both the OSMR and LIFR in humans, which prevents efficient translation of mouse data into potential clinical applications. We used an engineered human-like OSM (hlOSM) protein, capable to signal via both OSMR and LIFR, to evaluate beneficial effects on cardiomyocytes and hearts after MI in comparison to selective stimulation of either LIFR or OSMR. Cell viability assays, transcriptome and immunoblot analysis revealed increased survival of hypoxic cardiomyocytes by mLIF, mOSM and hlOSM stimulation, associated with increased activation of STAT3. Kinetic expression profiling of infarcted hearts further specified a transient increase of OSM and LIF during the early inflammatory phase of cardiac remodeling. A post-infarction delivery of hlOSM but not mOSM or mLIF within this time period combined with cardiac magnetic resonance imaging-based strain analysis uncovered a global cardioprotective effect on infarcted hearts. Our data conclusively suggest that a simultaneous and rapid activation of OSMR and LIFR after MI offers a therapeutic opportunity to preserve functional and structural integrity of the infarcted heart.

Cardiac fibroblasts display endurance to ischemia, high ROS control and elevated respiration regulated by the JAK2/STAT pathway

Cardiovascular diseases are the leading cause of death globally and more than four out of five cases are due to ischemic events. Cardiac fibroblasts (CF) contribute to normal heart development and function, and produce the post-ischemic scar. Here, we characterize the biochemical and functional aspects related to CF endurance to ischemia-like conditions. Expression data mining showed that cultured human CF (HCF) express more BCL2 than pulmonary and dermal fibroblasts. In addition, gene set enrichment analysis showed overrepresentation of genes involved in the response to hypoxia and oxidative stress, respiration and Janus kinase (JAK)/Signal transducer and Activator of Transcription (STAT) signaling pathways in HCF. BCL2 sustained survival and proliferation of cultured rat CF, which also had higher respiration capacity and reactive oxygen species (ROS) production than pulmonary and dermal fibroblasts. This was associated with higher expression of the electron transport chain (ETC) and antioxidant enzymes. CF had high phosphorylation of JAK2 and its effectors STAT3 and STAT5, and their inhibition reduced viability and respiration, impaired ROS control and reduced the expression of BCL2, ETC complexes and antioxidant enzymes. Together, our results identify molecular and biochemical mechanisms conferring survival advantage to experimental ischemia in CF and show their control by the JAK2/STAT signaling pathway. The presented data point to potential targets for the regulation of cardiac fibrosis and also open the possibility of a general mechanism by which somatic cells required to acutely respond to ischemia are constitutively adapted to survive it.

A Systematic Review of the Utility of Bromocriptine in Acute Peripartum Cardiomyopathy

In formerly healthy females, acute heart failure (HF) of an unknown cause that develops during the last weeks of gestation or in the first months after childbirth is known as peripartum cardiomyopathy (PPCM). This study aimed to establish the therapeutic value of combining bromocriptine with conventional HF treatment on left ventricular ejection fraction (LVEF), death, thromboembolic events, left ventricular (LV) dysfunction recurrence in subsequent pregnancies in PPCM women, and newborn children's outcomes. We conducted a systematic review to find clinical studies that described the utility of bromocriptine in addition to conventional HF treatment compared to conventional HF treatment only in the management of acute PPCM. Four databases comprising records from July 10, 2001, to July 10, 2021, were analyzed, including PubMed (MEDLINE), Google Scholar, Scopus, and the Cochrane Library. We discovered 4,717 potentially eligible records across all the databases. According to our eligibility criteria, we included six studies consisting of 263 patients in this review. Bromocriptine combined with conventional HF therapy led to an 11.37% increase in LVEF (mean difference: 11.37; 95% confidence interval [CI]: 9.55-13.19; p-value = 0.001) after six months compared to conventional HF treatment only. Notably, bromocriptine combined with conventional HF treatment reduced mortality associated with PPCM, and no thromboembolism events were recorded in the 263 patients. PPCM is a severe condition affecting women globally. In this study, the combination of bromocriptine with conventional HF treatment enhanced the LVEF of women with acute PPCM and their clinical outcomes.

Peripartum cardiomyopathy: a review

Peripartum cardiomyopathy is a form of idiopathic systolic heart failure which occurs during the end of pregnancy or the early post-partum in the absence of an identifiable etiology. The exact pathogenesis remains unknown, and the incidence is higher in African ancestry, multiparous and hypertensive women, or older maternal age. Delay in diagnosis is common, mainly because symptoms of heart failure mimic those of normal pregnancy. Echocardiography showing decreased myocardial function is at the center of the diagnosis. Management relies on the general guidelines of management of other forms of non-ischemic cardiomyopathy; however, special attention should be paid when choosing medications to ensure fetal safety. Outcomes can be variable and can range from complete recovery to persistent heart failure requiring transplant or even death. High rates of relapse with subsequent pregnancies can occur, especially with incomplete myocardial recovery. Additional research about the etiology, experimental drugs, prognosis, and duration of treatment after recovery are needed.

Peripartum cardiomyopathy

Peripartum cardiomyopathy is now increasingly recognized as a cause of heart failure in the later months of pregnancy and early postpartum period. Clinical diagnosis may be challenging as it closely resembles several common medical and obstetric complications. Complex pathogenesis, unpredictable onset, staggered recovery, and unanticipated fetomaternal risks pose unique challenge to clinicians. Prevalence seems to vary with race, geographic location, and diagnostic criteria. The presence of multiple risk factors substantially elevates the risk of PPCM. Transthoracic echocardiographic examination can exclude the majority of the mimickers. Symptomatic presentation is initially limited to, varying grades of low cardiac output syndrome. Rarely, PPCM begins with decompensated heart failure and cardiovascular collapse. Guideline-directed medical therapy involves graded initiation and titration of heart failure medications while ensuring the fetal and neonatal safety. Anesthetic and obstetric management should be individualized to improve fetomaternal outcomes. However, emergent cesarean delivery may be required in women with decompensated heart failure and cardiovascular collapse. An early institution of mechanical circulatory support has shown to improve outcome. Bromocriptine and other experimental drugs designed to target pathogenic pathway have yielded mixed results. A further change in approach to management requires a comprehensive understanding of pathophysiology and fetomaternal safety profiles of heart failure medications.

The optimization conditions of establishing an H9c2 cardiomyocyte hypoxia/reoxygenation injury model based on an AnaeroPack System

Ischemia-reperfusion (I/R) injury is a major cause of cardiomyocyte apoptosis after vascular recanalization, which was mimicked by a hypoxia/reoxygenation (H/R) injury model of cardiomyocytes in vitro. In this study, we explored an optimal H/R duration procedure using the AnaeroPack System. To study the H/R procedure, cardiomyocytes were exposed to the AnaeroPack System with sugar and serum-free medium, followed by reoxygenation under normal conditions. Cell injury was detected through lactate dehydrogenase (LDH) and cardiac troponin (c-Tn) release, morphological changes, cell apoptosis, and expression of apoptosis-related proteins. The results showed that the damage to H9c2 cells increased with prolonged hypoxia time, as demonstrated by increased apoptosis rate, LDH and c-Tn release, HIF-1α expression, as well as decreased expression of Bcl-2. Furthermore, hypoxia for 10 h and reoxygenation for 6 h exhibited the highest apoptosis rate and damage and cytokine release; in addition, cells were deformed, small, and visibly round. After 12 h of hypoxia, the majority of the cells were dead. Taken together, this study showed that subjecting H9c2 cells to the AnaeroPack System for 10 h and reoxygenation for 6 h can achieve a practicable and repeatable H/R injury model.

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.

Human-induced pluripotent stem cells for modelling metabolic perturbations and impaired bioenergetics underlying cardiomyopathies

Normal cardiac contractile and relaxation functions are critically dependent on a continuous energy supply. Accordingly, metabolic perturbations and impaired mitochondrial bioenergetics with subsequent disruption of ATP production underpin a wide variety of cardiac diseases, including diabetic cardiomyopathy, dilated cardiomyopathy, hypertrophic cardiomyopathy, anthracycline cardiomyopathy, peripartum cardiomyopathy, and mitochondrial cardiomyopathies. Crucially, there are no specific treatments for preventing the onset or progression of these cardiomyopathies to heart failure, one of the leading causes of death and disability worldwide. Therefore, new treatments are needed to target the metabolic disturbances and impaired mitochondrial bioenergetics underlying these cardiomyopathies in order to improve health outcomes in these patients. However, investigation of the underlying mechanisms and the identification of novel therapeutic targets have been hampered by the lack of appropriate animal disease models. Furthermore, interspecies variation precludes the use of animal models for studying certain disorders, whereas patient-derived primary cell lines have limited lifespan and availability. Fortunately, the discovery of human-induced pluripotent stem cells has provided a promising tool for modelling cardiomyopathies via human heart tissue in a dish. In this review article, we highlight the use of patient-derived iPSCs for studying the pathogenesis underlying cardiomyopathies associated with metabolic perturbations and impaired mitochondrial bioenergetics, as the ability of iPSCs for self-renewal and differentiation makes them an ideal platform for investigating disease pathogenesis in a controlled in vitro environment. Continuing progress will help elucidate novel mechanistic pathways, and discover novel therapies for preventing the onset and progression of heart failure, thereby advancing a new era of personalized therapeutics for improving health outcomes in patients with cardiomyopathy.

Pregnancy-associated cardiac dysfunction and the regulatory role of microRNAs

Many crucial cardiovascular adaptations occur in the body during pregnancy to ensure successful gestation. Maladaptation of the cardiovascular system during pregnancy can lead to complications that promote cardiac dysfunction and may lead to heart failure (HF). About 12% of pregnancy-related deaths in the USA have been attributed to HF and the detrimental effects of cardiovascular complications on the heart can be long-lasting, pre-disposing the mother to HF later in life. Indeed, cardiovascular complications such as gestational diabetes mellitus, preeclampsia, gestational hypertension, and peripartum cardiomyopathy have been shown to induce cardiac metabolic dysfunction, oxidative stress, fibrosis, apoptosis, and diastolic and systolic dysfunction in the hearts of pregnant women, all of which are hallmarks of HF. The exact etiology and cardiac pathophysiology of pregnancy-related complications is not yet fully deciphered. Furthermore, diagnosis of cardiac dysfunction in pregnancy is often made only after clinical symptoms are already present, thus necessitating the need for novel diagnostic and prognostic biomarkers. Mounting data demonstrates an altered expression of maternal circulating miRNAs during pregnancy affected by cardiovascular complications. Throughout the past decade, miRNAs have become of growing interest as modulators and biomarkers of pathophysiology, diagnosis, and prognosis in cardiac dysfunction. While the association between pregnancy-related cardiovascular complications and cardiac dysfunction or HF is becoming increasingly evident, the roles of miRNA-mediated regulation herein remain poorly understood. Therefore, this review will summarize current reports on pregnancy-related cardiovascular complications that may lead to cardiac dysfunction and HF during and after pregnancy in previously healthy women, with a focus on the pathophysiological role of miRNAs.

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.

Anthracycline and Peripartum Cardiomyopathies

Anthracycline-associated cardiomyopathy and peripartum cardiomyopathy are nonischemic cardiomyopathies that often afflict previously healthy young patients; both diseases have been well described since at least the 1970s and both occur in the settings of predictable stressors (ie, cancer treatment and pregnancy). Despite this, the precise mechanisms and the ability to reliably predict who exactly will go on to develop cardiomyopathy and heart failure in the face of anthracycline exposure or childbirth have proven elusive. For both cardiomyopathies, recent advances in basic and molecular sciences have illuminated the complex balance between cardiomyocyte and endothelial homeostasis via 3 broad pathways: reactive oxidative stress, interference in apoptosis/growth/metabolism, and angiogenic imbalance. These advances have already shown potential for specific, disease-altering therapies, and as our mechanistic knowledge continues to evolve, further clinical successes are expected to follow.

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.

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.

Peripartum cardiomyopathy: basic mechanisms and hope for new therapies

Peripartum cardiomyopathy (PPCM) is a life-threatening cardiomyopathy characterized by acute or slow progression of left ventricular (LV) systolic dysfunction (LV ejection fraction of <45%) late in pregnancy, during delivery, or in the first postpartum months, in women with no other identifiable causes of heart failure. PPCM patients display variable phenotypes and risk factor profiles, pointing to involvement of multiple mechanisms in the pathogenesis of the disease. The higher risk for PPCM in women with African ancestry, the prevalence of gene variants associated with cardiomyopathies, and the high variability in onset and disease progression in PPCM patients also indicate multiple mechanisms at work. Experimental data have shown that different factors can induce and drive PPCM, including inflammation and immunity, pregnancy hormone impairment, catecholamine stress, defective cAMP-PKA, and G-protein-coupled-receptor signalling, and genetic variants. However, several of these mechanisms may merge into a common major pathway, which includes unbalanced oxidative stress and the cleavage of the nursing hormone prolactin (PRL) into an angiostatic, pro-apoptotic, and pro-inflammatory 16 kDa-PRL fragment, resulting in subsequent vascular damage and heart failure. Based on this common pathway, potential disease-specific biomarkers and therapies have emerged. Despite commonalities, the variation in aetiology and mechanisms poses challenges for the diagnosis, treatment, and management of the disease. This review summarizes current knowledge on the clinical presentation of PPCM in the context of recent experimental research. It discusses the challenge to develop disease-specific biomarkers in the context of rapid changing physiology in the peripartum phase, and outlines possible future treatment and management strategies for PPCM patients.

Cardiotrophin-1 opposes renal fibrosis in mice: Potential prevention of chronic kidney disease

AIM

Chronic kidney disease is characterized by tubulointerstitial fibrosis involving inflammation, tubular apoptosis, fibroblast proliferation and extracellular matrix accumulation. Cardiotrophin-1, a member of the interleukin-6 family of cytokines, protects several organs from damage by promoting survival and anti-inflammatory effects. However, whether cardiotrophin-1 participates in the response to chronic kidney injury leading to renal fibrosis is unknown.

METHODS

We hypothesized and assessed the potential role of cardiotrophin-1 in a mice model of tubulointerstitial fibrosis induced by unilateral ureteral obstruction (UUO).

RESULTS

Three days after UUO, obstructed kidneys from cardiotrophin-1^-/- mice show higher expression of inflammatory markers IL-1β, Cd68, ICAM-1, COX-2 and iNOs, higher activation of NF-κB, higher amount of myofibroblasts and higher severity of tubular damage and apoptosis, compared with obstructed kidneys from wild-type littermates. In a later stage, obstructed kidneys from cardiotrophin-1^-/- mice show higher fibrosis than obstructed kidneys from wild-type mice. Interestingly, administration of exogenous cardiotrophin-1 prevents the increased fibrosis resulting from the genetic knockout of cardiotrophin-1 upon UUO, and supplementation of wild-type mice with exogenous cardiotrophin-1 further reduces the renal fibrosis induced by UUO. In vitro, renal myofibroblasts from cardiotrophin-1^-/- mice have higher collagen I and fibronectin expression and higher NF-κB activation than wild-type cells.

CONCLUSIONS

Cardiotrophin-1 participates in the endogenous response that opposes renal damage by counteracting the inflammatory, apoptotic and fibrotic processes. And exogenous cardiotrophin-1 is proposed as a candidate for the treatment and prevention of chronic renal fibrosis.

Acylated ghrelin prevents doxorubicin-induced cardiac intrinsic cell death and fibrosis in rats by restoring IL-6/JAK2/STAT3 signaling pathway and inhibition of STAT1

This study investigated if JAK/STAT signaling pathway mediates doxorubicin (DOX)-induced cell death and fibrosis in left ventricles (LVs) of rats and examined if acylated ghrelin affords protection by modulating this pathway. Male rats (120 ± 5 g) were divided into 6 groups (10 rats each) as follows: control; control + AG (10 ng/kg, s.c.); DOX (an accumulative dose 15 mg/kg, i.p.); DOX + AG, DOX + AG + AG490, a JAK2 inhibitor (5 mg/kg, i.p.); and DOX + AG + [D-Lys3]-GHRP-6; an AG receptor antagonist (3.75 mg/kg, i.p.). All treatments were carried out for 35 days. In rats' LVs, DOX significantly impaired the systolic and diastolic functions, enhanced levels of ROS and MDA, reduced levels of GSH and Bcl-2, and increased mRNA and protein levels of collagen I/III and TGF-β and cleaved caspase-3. In addition, although DOX did not affect JAK1 or JAK2 activity, it significantly increased protein levels of IL-6, decreased STAT3 and p-STAT3 (Tyr701&Ser727), and increased STAT1 and p-STAT1 (Tyr701&Ser727) levels, with a concomitant decrease in ERK1/2 activity and an increase in P38 activity. However, without affecting IL-6 and JAK1/2, AG reversed all of the observed alterations with a significant increase in the levels and activities of JAK2. Similar effects of AG were also seen in control rats. Interestingly, all the beneficial effects afforded by AG were abolished by AG490 and AG + [D-Lys3]-GHRP-6. In conclusion, DOX-induced cardiac toxicity involves stimulation of IL-6, P38, and STAT1 signaling levels whereas the protective effect afforded by AG involves the activation of ERK1/2 and JAK2/STAT3 and inhibition of STAT1.

Remote transplantation of human adipose-derived stem cells induces regression of cardiac hypertrophy by regulating the macrophage polarization in spontaneously hypertensive rats

Left ventricular hypertrophy (LVH) in hypertension has prognostic significance on cardiovascular mortality and morbidity. Recently, we have shown that n-butylidenephthalide (BP) improves human adipose-derived stem cell (hADSC) engraftment via attenuated reactive oxygen species (ROS) production. This prompted us to investigate whether remote transplantation of BP-pretreated hADSCs confers attenuated LVH at an established phase of hypertension. Male spontaneously hypertensive rats (SHRs) aged 12 weeks were randomly allocated to receive right hamstring injection of vehicle, clinical-grade hADSCs, and BP-preconditioned hADSCs for 8 weeks. As compared with untreated SHRs, naïve hADSCs decreased the ratio of LV weight to tibia, cardiomyocyte cell size, and collagen deposition independent of hemodynamic changes. These changes were accompanied by attenuated myocardial ROS production and increased p-STAT3 levels. Compared with naïve hADSCs, BP-preconditioned hADSCs provided a further decrease of ROS and LVH and an increase of local hADSC engraftment, STAT3 phosphorylation, STAT3 activity, STAT3 nuclear translocation, myocardial IL-10 levels, and the percentage of M2 macrophage infiltration. SIN-1 or S3I-201 reversed the effects of BP-preconditioned ADSCs increase on myocardial IL-10 levels. Furthermore, SIN-1 abolished the phosphorylation of STAT3, whereas superoxide levels were not affected following the inhibition of STAT3. Our results highlighted the feasibility of remote transplantation of hADSCs can be considered as an alternative procedure to reverse cardiac hypertrophy even at an established phase of hypertension. BP-pretreated hADSCs polarize macrophages into M2 immunoregulatory cells more efficiently than naïve hADSCs via ROS/STAT3 pathway.

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Hypertension was associated with left ventricular hypertrophy.

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Compared with untreated SHRs, naïve hADSCs injected at the right hamstring decreased LV mass and cardiomyocyte cell size.

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BP-preconditioned ADSCs provided a further increase of the M2 macrophage infiltration.

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The beneficial effects of BP-preconditioned stem cell administration can be abolished by exogenous SIN-1 or 3SI-201.

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Remote transplantation of hADSCs can be considered as an alternative procedure to reverse cardiac hypertrophy.

Peripartum cardiomyopathy

Peripartum cardiomyopathy (PPCM) is a rare, often dilated, cardiomyopathy with systolic dysfunction that presents in late pregnancy or, more commonly, the early postpartum period. Although the condition is prevalent worldwide, women with black ancestry seem to be at greatest risk, and the condition has a particularly high incidence in Nigeria and Haiti. Other risk factors include pre-eclampsia, advanced maternal age, and multiple gestation pregnancy. Although the complete pathophysiology of peripartum cardiomyopathy remains unclear, research over the past decade suggests the importance of vasculo-hormonal pathways in women with underlying susceptibility. At least some women with the condition harbor an underlying sarcomere gene mutation. More than half of affected women recover systolic function, although some are left with a chronic cardiomyopathy, and a minority requires mechanical support or cardiac transplantation (or both). Other potential complications include thromboembolism and arrhythmia. Currently, management entails standard treatments for heart failure with reduced ejection fraction, with attention to minimizing potential adverse effects on the fetus in women who are still pregnant. Bromocriptine is one potential disease specific treatment under investigation. In this review, we summarize the current literature on peripartum cardiomyopathy, as well as gaps in the understanding of this condition and future research directions.

Oxygen exposure deprives antimonate-reducing capability of a methane fed biofilm

This work is aiming at achieving antimonate (Sb(V)) bio-reduction in a methane (CH₄) based membrane biofilm reactor (MBfR), and elucidating the effect of oxygen (O₂) on the performance of the biofilm. Scanning electron microscope (SEM), energy dispersive X-ray (EDS) and X-ray photoelectron spectroscopy (XPS) confirm Sb₂O₃ precipitates were the main product formed from Sb(V) reduction in the CH₄-fed biofilm. Illumina sequencing shows Thermomonas may be responsible for Sb(V) reduction. Moreover, we found 8 mg/L of O₂ in the influent irreversibly inhibited Sb(V) reduction. Metagenomic prediction by Reconstruction of Unobserved State (PICRUSt) shows that the biofilm lacked efficient defense system to the oxidative stress, leading to the great suppress of key biological metabolisms such as TCA cycle, glycolysis and DNA replication, as well as potential Sb(V) reductases, by O₂. However, methanotrophs Methylomonas and Methylosinus were enriched in the biofilm with O₂ intrusion, in accordance with the enhanced abundance of genes encoding aerobic CH₄ oxidation. These insights evoke the theoretical guidance of microbial remediation using CH₄ as the electron donor towards Sb(V) contamination, and will give us a strong reference with regard to wastewater disposal.

The AB loop of oncostatin M (OSM) determines species-specific signaling in humans and mice

The pleiotropic interleukin-6 (IL-6)-type cytokine oncostatin M (OSM) signals in multiple cell types, affecting processes such as cell differentiation, hematopoiesis, and inflammation. In humans, OSM exerts its effects through activation of either of two different heterodimeric receptor complexes, formed by glycoprotein 130 (gp130) and either OSM receptor (OSMR) or leukemia inhibitory factor receptor (LIFR). In contrast, the mouse OSM orthologue acts mainly through dimers containing OSMR and gp130 and shows limited activity through mouse LIFR. Despite their structural similarity, neither human nor mouse OSM signal through the other species' OSMR. The molecular basis for such species-specific signaling, however, remains poorly understood. To identify key molecular features of OSM that determine receptor activation in humans and mice, we generated chimeric mouse-human cytokines. Replacing regions within binding site III of murine OSM with the human equivalents showed that the cytokine's AB loop was critical for receptor selection. Substitutions of individual amino acids within this region demonstrated that residues Asn-37, Thr-40, and Asp-42 of the murine cytokine were responsible for limited LIFR activation and absence of human OSMR/LIFR signaling. In human OSM, Lys-44 appeared to be the main residue preventing mouse OSMR activation. Our data reveal that individual amino acids within the AB loop of OSM determine species-specific activities. These mutations might reflect a key step in the evolutionary process of this cytokine, in which receptor promiscuity gives way to ligand-receptor specialization.

Comparative analysis of inflammatory gene expression levels in metabolic syndrome & coronary artery disease

BACKGROUND & OBJECTIVES

Metabolic syndrome (MetS) increases the likelihood of developing coronary artery disease (CAD), and inflammation is involved in the pathogenesis of both these conditions. The present work was conducted to examine the relative expression of 18 key inflammatory genes associated with MetS and incident CAD in a representative group of patients.

METHODS

A total of 178 male patients, including 57 with CAD and 121 without CAD, were enrolled in the study. The participants without CAD were characterized for the presence of MetS using modified criteria specific for Asian Indians, which included a lower cut-off for waist circumference (≥90 cm for men). The expression of 18 inflammatory genes was evaluated in peripheral whole blood by quantitative polymerase chain reaction method.

RESULTS

Of the 121 participants without CAD, 53 (43.8%) had three or more risk factors (MetS group), 50 (41.3%) had one or two risk factors (non-MetS group), while 18 (14.8%) did not have any risk factors (control group). High nuclear factor-kappa B (NF-κB) expression levels and low interleukin-10 (IL-10) levels were observed in MetS patients. Linear association was seen between NF-κB and vascular endothelial growth factor A (VEGFA) expression and with increase in MetS components. Comparison of gene expression pattern between CAD and MetS revealed significantly higher expression of leukotriene genes - arachidonate 5-lipoxygenase (ALOX5), arachidonate 5-lipoxygenase activating protein (ALOX5 AP), leukotriene A4 hydrolase (LTA4H) and leukotriene C4 synthase (LTC4S), and lower expression of NF-κB, interleukin 1 beta (IL-1β), monocyte chemoattractant protein-1 (MCP-1/CCL2) and signal transducer and activator of transcription 3 (STAT3) genes in CAD. There was linear increase in expression of LTA4H, LTC4S, IL-8 and VEGFA genes across the four groups, namely from controls, non-MetS, MetS and CAD.

INTERPRETATION & CONCLUSIONS

A distinct gene expression pattern was seen in MetS and CAD implying a well-orchestrated inflammatory and immune activity. Specifically, NF-κB might be playing an active role in MetS, allowing further expansion of the inflammatory process with resolution of inflammation in full-blown CAD, wherein other gene players such as leukotrienes may dominate.

Mechanisms of Mitochondrial Redox Signaling in Psychosocial Stress-Responsive Systems: New Insights into an Old Story

SIGNIFICANCE

Psychosocial stress is associated with alterations in serum glucocorticoids and cytokines, such as interleukin-6 (IL-6) and IL-1β, which functionally interact. However, the molecular mechanisms and physiological relationship between the two systems within the context of stress exposure are not well characterized. Recent Advances: Extracellular IL-6, which stimulates the release of cortisol from the zona fasciculata of the adrenal cortex, mediates its intracellular effects by tyrosine phosphorylation of the transcription factor signal transducer and activator of transcription 3 (STAT3). Mitochondrial electron transfer reactions are involved in both STAT3-driven ATP production in oxidative respiration and adrenocortical steroid biosynthesis.

CRITICAL ISSUES

The role of STAT3 in oxidative respiration and steroidogenesis suggests that it integrates both nuclear and mitochondrial actions, thereby preserving main steps of glucocorticoid biosynthesis in the adrenal gland under psychosocial stress. This review discusses the notion that these two pathways are together simultaneously involved in protection against chronic stressors.

FUTURE DIRECTIONS

Linking the function of cytokines and main components of the hypothalamic-pituitary-adrenal (HPA) axis to molecular mechanisms of mitochondrial redox signaling will be essential for a better understanding of the relevant stress-responsive systems engaged in stress vulnerability. Antioxid. Redox Signal. 28, 760-772.

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.

Guidelines for experimental models of myocardial ischemia and infarction

Myocardial infarction is a prevalent major cardiovascular event that arises from myocardial ischemia with or without reperfusion, and basic and translational research is needed to better understand its underlying mechanisms and consequences for cardiac structure and function. Ischemia underlies a broad range of clinical scenarios ranging from angina to hibernation to permanent occlusion, and while reperfusion is mandatory for salvage from ischemic injury, reperfusion also inflicts injury on its own. In this consensus statement, we present recommendations for animal models of myocardial ischemia and infarction. With increasing awareness of the need for rigor and reproducibility in designing and performing scientific research to ensure validation of results, the goal of this review is to provide best practice information regarding myocardial ischemia-reperfusion and infarction models.

Listen to this article’s corresponding podcast at ajpheart.podbean.com/e/guidelines-for-experimental-models-of-myocardial-ischemia-and-infarction/.

Long-term Intake of Pasta Containing Barley (1-3)Beta-D-Glucan Increases Neovascularization-mediated Cardioprotection through Endothelial Upregulation of Vascular Endothelial Growth Factor and Parkin

Barley (1-3)β-D-Glucan (BBG) enhances angiogenesis. Since pasta is very effective in providing a BBG-enriched diet, we hypothesized that the intake of pasta containing 3% BBG (P-BBG) induces neovascularization-mediated cardioprotection. Healthy adult male C57BL/6 mice fed P-BBG (n = 15) or wheat pasta (Control, n = 15) for five-weeks showed normal glucose tolerance and cardiac function. With a food intake similar to the Control, P-BBG mice showed a 109% survival rate (P < 0.01 vs. Control) after cardiac ischemia (30 min)/reperfusion (60 min) injury. Left ventricular (LV) anion superoxide production and infarct size in P-BBG mice were reduced by 62 and 35% (P < 0.0001 vs. Control), respectively. The capillary and arteriolar density of P-BBG hearts were respectively increased by 12 and 18% (P < 0.05 vs. Control). Compared to the Control group, the VEGF expression in P-BBG hearts was increased by 87.7% (P < 0.05); while, the p53 and Parkin expression was significantly increased by 125% and cleaved caspase-3 levels were reduced by 33% in P-BBG mice. In vitro, BBG was required to induce VEGF, p53 and Parkin expression in human umbelical vascular endothelial cells. Moreover, the BBG-induced Parkin expression was not affected by pifithrin-α (10 uM/7days), a p53 inhibitor. In conclusion, long-term dietary supplementation with P-BBG confers post-ischemic cardioprotection through endothelial upregulation of VEGF and Parkin.

Foxc2 coordinates inflammation and browning of white adipose by leptin-STAT3-PRDM16 signal in mice

AIMS

The objective of this study is to characterize the relationship between forkhead box C2 protein (Foxc2) and leptin under adipose inflammatory response.

METHODS

Lipopolysaccharide (LPS)-induced inflammatory model was conducted. Data from wild-type and ob/ob mice were used to compare the alternative role of leptin on Foxc2-mediated inflammation and browning. Transcriptional regulation and protein-protein interaction were analyzed by bioinformatics and proved by chromatin immunoprecipitation and co-immunoprecipitation experiment.

RESULTS

Foxc2 and leptin correlated with inflammation and browning of white adipose tissue (WAT) in LPS-treated mice. Moreover, Foxc2-mediated inhibition of inflammation involved downstream activation of leptin signal and promoted WAT browning. We then determined CREB, the potential transcriptional factor of leptin, was required for Foxc2-mediated inflammation in the regulation of WAT browning. Foxc2 alleviated adipocyte inflammation by reducing leptin-mediated Janus-activated kinase 2/signal transducer and activator of transcription 3 (STAT3) pathway. Importantly, STAT3 physically interacted with PRDM16 and formed a complex to promote WAT browning. Exogenous Foxc2 overexpression also ameliorated inflammation and promoted adipose browning in high fat diet (HFD)-induced obese mice.

CONCLUSIONS

Our results indicated that Foxc2 inhibited inflammation and promoted browning of WAT through positive regulation of leptin signal and the STAT3-PRDM16 complex. These findings identify a new potential means to prevent and treat obese caused metabolic syndrome of mammals.

The extracellular isoform of superoxide dismutase has a significant impact on cardiovascular ischaemia and reperfusion injury during cardiopulmonary bypass

OBJECTIVES

Cardiac surgery with cardiopulmonary bypass (CPB) provokes ischaemia and reperfusion injury (IRI). Superoxide is a main mediator of IRI and is detoxified by superoxide dismutases (SODs). Extracellular SOD (SOD3) is the prevailing isoform in the cardiovascular system. Its mutation is associated with elevated risk for ischaemic heart disease as epidemiological and experimental studies suggest. We investigated the influence of SOD3 on IRI in the context of CPB and hypothesized a protective role for this enzyme.

METHODS

Mutant rats with loss of SOD3 function induced by amino acid shift, SOD3-E124D, (SOD3 mutant; n = 9) were examined in a model of CPB with deep hypothermic circulatory arrest provoking global IRI and compared with SOD3 competent controls (n = 8) as well as sham animals (n = 7). SOD3 plasma activity was photometrically measured with a diazo dye-forming reagent. Activation of cardioprotective rescue pathways (p44-42 MAPK and STAT3), cleavage of PARP-1, expression of SOD isoforms (SOD1, 2 and 3) and nitric oxide metabolism were analysed on the protein level by western blot. To evaluate whether SOD3 inactivity directly affects the myocardium, we isolated adult cardiac myocytes, which underwent hypoxia prior to protein analyses.

RESULTS

Relative SOD3 plasma activity in SOD3 mutant rats was significantly decreased by at least 50% compared with that in SOD3 competent controls (prior to euthanasia P = 0.008). Effectively, physiological parameters [heart rate and mean arterial pressure (MAP)] indicated a trend toward impaired handling of ischaemia and reperfusion in SOD3 mutants: after reperfusion, mean heart rate was 46 bpm lower (P = 0.083) and MAP 8 mmHg lower (P = 0.288) than that in SOD competent controls. Decreased SOD3 activity led to reduced activation of cardioprotective rescue pathways in vivo and in vitro: relative activation of p44-42 MAPK (P = 0.074) and STAT3 (P = 0.027) was more than 30% decreased in heart and aortic tissue of SOD3 mutants (activity normalized to sham control as 1). After CPB, cleavage of PARP-1 was doubled in the control group (P = 0.017), but increased 3-fold in SOD3 mutants (P = 0.002). Furthermore, 3-nitrotyrosine as a measure of decreased nitric oxide bioavailability and other SOD isoforms (SOD1 and 2) were increased.

CONCLUSIONS

Collectively, SOD3 has a significant cardioprotective role in cases of IRI and directly affects the myocardium as hypothesized. Exploration of intervention strategies targeting SOD3 may provide therapeutic options against IRI and associated systemic inflammation.

STAT3 mediates multidrug resistance of Burkitt lymphoma cells by promoting antioxidant feedback

Burkitt lymphoma (BL) is a highly aggressive B-cell neoplasm. Although BL is relatively sensitive to chemotherapy, some patients do not respond to initial therapy or relapse after standard therapy, which leads to poor prognosis. The mechanisms underlying BL chemoresistance remain poorly defined. Here, we report a mechanism for the relationship between the phosphorylation of STAT3 on Tyr705 and BL chemoresistance. In chemoresistant BL cells, STAT3 was activated and phosphorylated on Tyr705 in response to the generation of the reactive oxygen species (ROS), which induced Src Tyr416 phosphorylation after multi-chemotherapeutics treatment. As a transcription factor, the elevated phosphorylation level of STAT3^Y705 increased the expression of GPx1 and SOD2, both of which protected cells against oxidative damage. Our findings revealed that the ROS-Src-STAT3-antioxidation pathway mediated negative feedback inhibition of apoptosis induced by chemotherapy. Thus, the phosphorylation of STAT3 on Tyr705 might be a target for the chemo-sensitization of BL.

Sevoflurane postconditioning protects the myocardium against ischemia/reperfusion injury via activation of the JAK2-STAT3 pathway

BACKGROUND

Sevoflurane postconditioning (S-post) has similar cardioprotective effects as ischemic preconditioning. However, the underlying mechanism of S-post has not been fully elucidated. Janus kinase signaling transduction/transcription activator (JAK2-STAT3) plays an important role in cardioprotection. The purpose of this study was to determine whether the cardioprotective effects of S-post are associated with activation of the JAK2-STAT3 signal pathway.

METHODS

An adult male Sprague-Dawley (SD) rat model of myocardial ischemia/reperfusion (I/R) injury was established using the Langendorff isolated heart perfusion apparatus. At the beginning of reperfusion, 2.4% sevoflurane alone or in combination with AG490 (a JAK2 selective inhibitor) was used as a postconditioning treatment. The cardiac function indicators, myocardial infarct size, lactic dehydrogenase (LDH) release, mitochondrial ultrastructure, mitochondrial reactive oxygen species (ROS) generation rates, ATP content, protein expression of p-JAK, p-STAT3, Bcl-2 and Bax were measured.

RESULTS

Compared with the I/R group, S-post significantly increased the expression of p-JAK, p-STAT3 and Bcl-2 and reduced the protein expression of Bax, which markedly decreased the myocardial infarction areas, improved the cardiac function indicators and the mitochondrial ultrastructure, decreased the mitochondrial ROS and increased the ATP content. However, the cardioprotective effects of S-post were abolished by treatment with a JAK2 selective inhibitor (p < 0.05).

CONCLUSION

This study demonstrates that the cardioprotective effects of S-post are associated with the activation of JAK2-STAT3. The mechanism may be related to an increased expression of p-JAK2 and p-STAT3 after S-post, which reduced mitochondrial ROS generation and increased mitochondrial ATP content, thereby reducing apoptosis and myocardial infarct size.

Autophagy Promotes the Repair of Radiation-Induced DNA Damage in Bone Marrow Hematopoietic Cells via Enhanced STAT3 Signaling

Autophagy protects hematopoietic cells from radiation damage in part by promoting DNA damage repair. However, the molecular mechanisms by which autophagy regulates DNA damage repair remain largely elusive. Here, we report that this radioprotective effect of autophagy depends on STAT3 signaling in murine bone marrow mononuclear cells (BM-MNCs). Specifically, we found that STAT3 activation and nuclear translocation in BM-MNCs were increased by activation of autophagy with an mTOR inhibitor and decreased by knockout of the autophagy gene Atg7. The autophagic regulation of STAT3 activation is likely mediated by induction of KAP1 degradation, because we showed that KAP1 directly interacted with STAT3 in the cytoplasm and knockdown of KAP1 increased the phosphorylation and nuclear translocation of STAT3. Subsequently, activated STAT3 transcriptionally upregulated the expression of BRCA1, which increased the ability of BM-MNCs to repair radiation-induced DNA damage. This novel finding that activation of autophagy can promote DNA damage repair in BM-MNCs via the ATG-KAP1-STAT3-BRCA1 pathway suggests that autophagy plays an important role in maintaining genomic integrity of BM-MNCs and its activation may confer protection of BM-MNCs against radiation-induced genotoxic stress.

Mitochondrial Dysfunction and Myocardial Ischemia-Reperfusion: Implications for Novel Therapies

Mitochondria have emerged as key participants in and regulators of myocardial injury during ischemia and reperfusion. This review examines the sites of damage to cardiac mitochondria during ischemia and focuses on the impact of these defects. The concept that mitochondrial damage during ischemia leads to cardiac injury during reperfusion is addressed. The mechanisms that translate ischemic mitochondrial injury into cellular damage, during both ischemia and early reperfusion, are examined. Next, we discuss strategies that modulate and counteract these mechanisms of mitochondrial-driven injury. The new concept that mitochondria are not merely stochastic sites of oxidative and calcium-mediated injury but that they activate cellular responses of mitochondrial remodeling and cellular reactions that modulate the balance between cell death and recovery is reviewed, and the therapeutic implications of this concept are discussed.