Myocardial Hypoxia Research Articles

Xinyang Tablet attenuates chronic hypoxia-induced right ventricular remodeling via inhibiting cardiomyocytes apoptosis

BackgroundHypoxia-induced pulmonary hypertension (HPH) is one of the fatal pathologies developed under hypobaric hypoxia and eventually leads to right ventricular (RV) remodeling and RV failure. Clinically, the mortality rate of RV failure caused by HPH is high and lacks effective drugs. Xinyang Tablet (XYT), a traditional Chinese medicine exhibits significant efficacy in the treatment of congestive heart failure and cardiac dysfunction. However, the effects of XYT on chronic hypoxia-induced RV failure are not clear.MethodsThe content of XYT was analyzed by high-performance liquid chromatography-tandem mass spectrometry (HPLC–MS). Sprague–Dawley (SD) rats were housed in a hypobaric chamber (equal to the parameter in altitude 5500 m) for 21 days to obtain the RV remodeling model. Electrocardiogram (ECG) and hemodynamic parameters were measured by iWorx Acquisition & Analysis System. Pathological morphological changes in the RV and pulmonary vessels were observed by H&E staining and Masson’s trichrome staining. Myocardial apoptosis was tested by TUNEL assay. Protein expression levels of TNF-α, IL-6, Bax, Bcl-2, and caspase-3 in the RV and H9c2 cells were detected by western blot. Meanwhile, H9c2 cells were induced by CoCl2 to establish a hypoxia injury model to verify the protective effect and mechanisms of XYT. A CCK-8 assay was performed to determine the viability of H9c2 cells. CoCl2-induced apoptosis was detected by Annexin-FITC/PI flow cytometry and Hoechst 33,258 staining.ResultsXYT remarkably improved RV hemodynamic disorder and ECG parameters. XYT attenuated hypoxia-induced pathological injury in RV and pulmonary vessels. We also observed that XYT treatment decreased the expression levels of TNF-α, IL-6, Bax/Bcl-2 ratio, and the numbers of myocardial apoptosis in RV. In H9c2 myocardial hypoxia model, XYT protected H9c2 cells against Cobalt chloride (CoCl2)-induced apoptosis. We also found that XYT could antagonize CoCl2-induced apoptosis through upregulating Bcl-2, inhibiting Bax and caspase-3 expression.ConclusionsWe concluded that XYT improved hypoxia-induced RV remodeling and protected against cardiac injury by inhibiting apoptosis pathway in vivo and vitro models, which may be a promising therapeutic strategy for clinical management of hypoxia-induced cardiac injury.

Abstract 11646: Impact of Fetal Hypoxia on Myocardial Molecular Profile in the Lamb Extra-Uterine Environment for Neonatal Development

Background: Using the EXTrauterine Environment for Neonatal Development (EXTEND) system to chronically reduce myocardial oxygen delivery (DO 2 ) to levels mimicking human congenital heart disease caused increased myocardial capillarity and cardiomyocyte hypotrophy. However, molecular mechanisms for this have not been evaluated. Methods: Preterm fetal lambs were isolated by cesarean section and supported by EXTEND for 7 days in normoxia (n=5) or hypoxia (n=4) and compared to in utero gestational age matched controls (n=3). Right and left ventricle (RV, LV) molecular profiles were assessed by RNAseq, qPCR, and western blot. Differentially expressed genes (DEGs) were identified with limma/edgeR. BioPlanet enrichment analysis was performed with Enrichr. Results: DO 2 was lower in hypoxic lambs (15.5 vs 23.8 ml/kg/min, p<0.0001). RNAseq revealed no significant DEGs between normoxia and control, while hypoxia significantly altered myocardial gene expression. The directionality was similar for LV and RV (r=0.82, p<0.0001), but more statistically significant in LV (97 vs 7 DEGs, adj p<0.05). Enrichment analysis revealed Hif1-target upregulation. qPCR confirmed upregulation of Hif1 targets and apoptosis activators Bnip3 (RV log 2 fold change (FC) 0.8) and Bnip3l (LV log 2 FC 1.6) and downregulation of the antiapoptotic Angpt1 (RV log 2 FC -1.5; all p<0.05). However, by protein, Bnip3 and Bnip3l were reduced (RV FC 0.6, p<0.0001) and (LV FC 0.8, p=0.0001), Bax was equally reduced (RV and LV FC 0.65, p<0.05), and the proangiogenic/antiapoptotic hormone Angptl4 was increased (FC 1.9 RV and 2.3 LV, p<0.05). In contrast, the proangiogenic/antiapoptotic cadherin receptor Cdh13 was reduced (RV and LV FC 0.5, p<0.05). Finally, Fblim1 , a driver of cardiomyocyte hypertrophy, was decreased in LV and RV by RNAseq (logFC -0.75 and -0.63, adj p<0.05) but increased by protein (LV FC 1.9, p=0.006). Conclusions: The normoxic EXTEND system faithfully recapitulates the myocardial molecular profile of normal lamb gestation. The molecular impact of fetal myocardial hypoxia is heterogeneous and suggests negative feedback loops with alterations in angiogenesis and cell survival/size. Future studies will dissect if these changes are sufficient to alter myocardial structure.

N-Acetylcysteine and Postoperative Atrial Fibrillation: Comment.

We read the article by Amar et al.1 with great interest. Their trial addressed whether N-acetylcysteine can prevent atrial fibrillation after thoracic surgery. A secondary analysis examined perioperative systemic markers of inflammation, oxidative stress, and the incidence of atrial fibrillation after discharge. We thank the authors for contributing to our understanding on this important topic. However, we have two questions regarding subgroup analysis.First, the primary endpoint analysis included surgical procedures such as open thoracotomy, minimally invasive video-assisted thoracoscopic, robotic-assisted approaches, and Ivor Lewis esophagectomy. However, there was not a subgroup analysis by surgical modality. Of note, the incidence of postoperative atrial fibrillation is influenced by the extent of lung resection2 and by the operative site (left more than right lobectomy).3 Moreover, lobectomy removes more lung tissue than segmentectomy, which may induce myocardial hypoxia, thereby triggering atrial fibrillation.2,4 A subgroup analysis of N-acetylcysteine effect according to surgical approach may be informative.Second, the conclusion that N-acetylcysteine did not result in lower systemic markers of inflammation and oxidative stress should be interpreted with caution given the lack of power to identify these secondary outcomes. Perioperative drugs such as opioids and dexmedetomidine may affect intraoperative stress and inflammatory response. Oxycodone, for instance, has antioxidant and anti-inflammatory properties that protect against surgical stress by inhibiting the production of proinflammatory cytokines and lipid peroxidation.5 Therefore, it would be of interest to perform a more comprehensive analysis of potential pharmacologic influence on the results.Postoperative atrial fibrillation is an important clinical outcome in patients undergoing noncardiac thoracic surgery, and there is growing interest in its prevention and treatment. However, multiple factors contribute to postoperative atrial fibrillation and inflammatory response. If there is substantial heterogeneity of these risk factors in the study population, risk-stratified analysis is especially important for enhancing the credibility of clinical trials.Supported by Zhongshan City Social Welfare project No. 2020B1002.The authors declare no competing interests.

Expression pattern and diagnostic value of ferroptosis-related genes in acute myocardial infarction.

Ferroptosis is a form of regulatory cell death (RCD) caused by iron-dependent lipid peroxidation. The role of ferroptosis in the process of acute myocardial infarction (AMI) is still unclear and requires further study. Therefore, it is helpful to identify ferroptosis related genes (FRGs) involved in AMI and explore their expression patterns and molecular mechanisms. The AMI-related microarray datasets GSE66360 and GSE61144 were obtained using the Gene Expression Omnibus (GEO) online database. GO annotation, KEGG pathway enrichment analysis and Protein-protein interaction (PPI) analysis were performed for the common significant differential expression genes (CoDEGs) in these two datasets. The FRGs were obtained from the FerrDb V2 and the differentially expressed FRGs were used to identify potential biomarkers by receiver operating characteristic (ROC) analysis. The expression of these FRGs was verified using external dataset GSE60993 and GSE775. Finally, the expression of these FRGs was further verified in myocardial hypoxia model. A total of 131 CoDEGs were identified and these genes were mainly enriched in the pathways of "inflammatory response," "immune response," "plasma membrane," "receptor activity," "protein homodimerization activity," "calcium ion binding," "Phagosome," "Cytokine-cytokine receptor interaction," and "Toll-like receptor signaling pathway." The top 7 hub genes ITGAM, S100A12, S100A9, TLR2, TLR4, TLR8, and TREM1 were identified from the PPI network. 45 and 14 FRGs were identified in GSE66360 and GSE61144, respectively. FRGs ACSL1, ATG7, CAMKK2, GABARAPL1, KDM6B, LAMP2, PANX2, PGD, PTEN, SAT1, STAT3, TLR4, and ZFP36 were significantly differentially expressed in external dataset GSE60993 with AUC ≥ 0.7. Finally, ALOX5, CAMKK2, KDM6B, LAMP2, PTEN, PTGS2, and ULK1 were identified as biomarkers of AMI based on the time-gradient transcriptome dataset of AMI mice and the cellular hypoxia model. In this study, based on the existing datasets, we identified differentially expressed FRGs in blood samples from patients with AMI and further validated these FRGs in the mouse time-gradient transcriptome dataset of AMI and the cellular hypoxia model. This study explored the expression pattern and molecular mechanism of FRGs in AMI, providing a basis for the accurate diagnosis of AMI and the selection of new therapeutic targets.

Upregulation of circFOXP1 attenuates inflammation and apoptosis induced by ox-LDL in human umbilical vein endothelial cells by regulating the miR-185-5p/BCL-2 axis.

The pathogenesis of coronary artery disease (CAD) is closely related to an abnormal function of the coronary arteries due to myocardial ischemia, hypoxia, or necrosis, which poses a threat to human health. Therefore, this study was conducted to evaluate the role of circFOXP1 in controlling endothelial cell function during atherosclerosis (AS), and further investigate its potential molecular mechanism of regulation. Through Starbase database analysis, we predicted that circFOXP1 can sponge miR-185-5p that targets BCL-2. We found that interleukin (IL)-6, tumor necrois factor (TNF)-α, and IL-1β were significantly upregulated in high-fat diet (HFD)-induced apolipoprotein E-deficient (ApoE-/-) mice compared with those in the control mice. CircFOXP1 was also significantly upregulated in the AS-mice model and AS-cell model. Moreover, miR-185-5p overexpression was found to inhibit BCL-2 protein expression, which consequently reduced the proliferation, and increased the oxidized low-density lipoprotein (ox-LDL)-induced human umbilical vein endothelial cells (HUVECs) apoptotic rate. Taken together, our data show that circFOXP1 can further aggravate endothelial cell injury by regulating the miR-185-5p/BCL-2 signal axis.

Beneficial Effects of RNS60 in Cardiac Ischemic Injury.

RNS60 is a physically modified saline solution hypothesized to contain oxygen nanobubbles. It has been reported to reduce ischemia/reperfusion injury in a pig model of acute myocardial infarction. We investigated the effects of RNS60 during cardiac hypoxia in mice and as an additive to cardioplegic solution in rat hearts. ApoE−/−LDLr−/− mice were treated by intravenous injection of RNS60 or saline as a control while monitoring the ECG and post-hypoxic serum release of troponin T and creatine kinase activity. Hearts infused with Custodiol containing 10% RNS60 or saline as the control were subjected to 4 h of 4 °C preservation, followed by an assessment of myocardial metabolites, purine release, and mechanical function. RNS60 attenuated changes in the ECG STU area during hypoxia, while the troponin T concentration and creatine kinase activity were significantly higher in the serum of the controls. During reperfusion after 4 h of cold ischemia, the Custodiol/RNS60-treated hearts had about 30% lower LVEDP and better dp/dtmax and dp/dtmin together with a decreased release of purine catabolites vs. the controls. The myocardial ATP, total adenine nucleotides, and phosphocreatine concentrations were higher in the RNS60-treated hearts. This study indicates that RNS60 enhances cardioprotection in experimental myocardial hypoxia and under conditions of cardioplegic arrest. Improved cardiac energetics are involved in the protective effect, but complete elucidation of the mechanism requires further study.

Aortic stenosis and mitral regurgitation modify the effect of venoarterial extracorporeal membrane oxygenation on left ventricular function in cardiogenic shock

Venoarterial extracorporeal membrane oxygenation (VA-ECMO) is widely used in the treatment of patients experiencing cardiogenic shock (CS). However, increased VA-ECMO blood flow (EBF) may significantly impair left ventricular (LV) performance. The objective of the present study was to assess the effect of VA-ECMO on LV function in acute CS with concomitant severe aortic stenosis (AS) or mitral regurgitation (MR) in a porcine model. Eight female swine (45 kg) underwent VA-ECMO implantation under general anaesthesia and mechanical ventilation. Acute CS was induced by global myocardial hypoxia. Subsequently, severe AS was simulated by obstruction of the aortic valve, while severe MR was induced by mechanical destruction of the mitral valve. Haemodynamic and LV performance variables were measured at different rates of EBF rates (ranging from 1 to 4 L/min), using arterial and venous catheters, a pulmonary artery catheter, and LV pressure–volume catheter. Data are expressed as median (interquartile range). Myocardial hypoxia resulted in declines in cardiac output to 2.7 (1.9–3.1) L/min and LV ejection fraction to 15.2% (10.5–19.3%). In severe AS, increasing EBF from 1 to 4 L/min was associated with a significant elevation in mean arterial pressure (MAP), from 33.5 (24.2–34.9) to 56.0 (51.9–73.3) mmHg (P ˂ 0.01). However, LV volumes (end-diastolic, end-systolic, stroke) remained unchanged, and LV end-diastolic pressure (LVEDP) significantly decreased from 24.9 (21.2–40.0) to 19.1 (15.2–29.0) mmHg (P ˂ 0.01). In severe MR, increasing EBF resulted in a significant elevation in MAP from 49.0 (28.0–53.4) to 72.5 (51.4–77.1) mmHg (P ˂ 0.01); LV volumes remained stable and LVEDP increased from 17.1 (13.7–19.1) to 20.8 (16.3–25.6) mmHg (P ˂ 0.01). Results of this study indicate that the presence of valvular heart disease may alleviate negative effect of VA-ECMO on LV performance in CS. Severe AS fully protected against LV overload, and partial protection was also detected with severe MR, although at the cost of increased LVEDP and, thus, higher risk for pulmonary oedema.

Stearoyl-CoA Desaturase Regulates Angiogenesis and Energy Metabolism in Ischemic Cardiomyocytes.

New blood vessel formation is a key component of the cardiac repair process after myocardial infarction (MI). Hypoxia following MI is a major driver of angiogenesis in the myocardium. Hypoxia-inducible factor 1α (HIF1α) is the key regulator of proangiogenic signaling. The present study found that stearoyl-CoA desaturase (SCD) significantly contributed to the induction of angiogenesis in the hypoxic myocardium independently of HIF1α expression. The pharmacological inhibition of SCD activity in HL-1 cardiomyocytes and SCD knockout in an animal model disturbed the expression and secretion of proangiogenic factors including vascular endothelial growth factor-A, proinflammatory cytokines (interleukin-1β, interleukin-6, tumor necrosis factor α, monocyte chemoattractant protein-1, and Rantes), metalloproteinase-9, and platelet-derived growth factor in ischemic cardiomyocytes. These disturbances affected the proangiogenic potential of ischemic cardiomyocytes after SCD depletion. Together with the most abundant SCD1 isoform, the heart-specific SCD4 isoform emerged as an important regulator of new blood vessel formation in the murine post-MI myocardium. We also provide evidence that SCD shapes energy metabolism of the ischemic heart by maintaining the shift from fatty acids to glucose as the substrate that is used for adenosine triphosphate production. Furthermore, we propose that the regulation of the proangiogenic properties of hypoxic cardiomyocytes by key modulators of metabolic signaling such as adenosine monophosphate kinase, protein kinase B (AKT), and peroxisome-proliferator-activated receptor-γ coactivator 1α/peroxisome proliferator-activated receptor α depends on SCD to some extent. Thus, our results reveal a novel mechanism that links SCD to cardiac repair processes after MI.

Chromium picolinate supplementation improves cardiac performance in hypoxic rats

Background Conditions associated with chronic hypoxia increase morbidity and mortality attributable to cardiovascular complications. Myocardial hypoxia is a common feature in several diseases including: stroke, infarction, anaemia, chronic lung diseases, obstructive sleep apnoea and cyanotic congenital heart defects. The present study was planned to investigate the cardiovascular effects of chronic intermittent hypoxia and its association with increased myocardial oxidative stress. In addition, to evaluate the protective effect of chromium supplementation, aiming at achieving an alternative that may enable to devise a therapy for hypoxic patients. Methods Male rats were allocated into three groups: control group (normoxic), untreated hypoxic group (exposed to hypoxia 8 h/day, 5 days/week for 6 weeks) and hypoxic group supplemented with chromium picolinate (90 µg/kg/day by gavage). Rats were subjected to measurement of body weight, haematocrit value, mean arterial blood pressure, heart rate and ECG recording. Cardiac activities of isolated hearts were studied on Langendorff preparation under basal conditions and in response to ischaemia/reperfusion. Thereafter, cardiac weights were determined and cardiac tissue catalase activity as well as malondialdhyde level were assessed. Results Significant results were obtained upon exposure to hypoxia including; low body weight, increased haematocrit, elevated blood pressure, left ventricular hypertrophy and impaired cardiac activities, basally and in response to ischaemia/reperfusion challenges, associated with increased oxidative stress in cardiac tissue. At the same time, chromium supplementation increased body weight, lowered blood pressure, reduced ventricular hypertrophy and significantly improved the cardiac performance. Conclusion Chromium supplementation confers protection against hypoxia-induced cardiovascular dysfunction by improvement of the antioxidant capacity.

Abstract P1043: Myocardial Infarction Induces Translocation Of Gut Bacteria To The Heart

Introduction: Myocardial hypoxia & intestinal hyperpermeability (IH) are two important events commonly observed in the aftermath of a myocardial infarction (MI) event. Recent studies have shown that gut bacteria and their metabolites are able to leak into the systemic circulation due to post-MI IH. Hypothesis: We hypothesized that facultative anaerobic gut bacteria such as E. coli will be able to translocate and colonize the hypoxic heart post-MI. Methods: C57 mice were given an oral administration of 10e9 cfu of luciferase/GFP expressing E. coli Nissle (EcN). Permanent occlusion of LAD arteries was performed to induce MI. Mouse hearts were checked for presence of EcN using PCR at different timepoints (n=32), IHC (n=4), and siderophore-based PET imaging (n=2). Immunoblotting of heart tissue lysate was used to check for presence of GFP. Results: PCR amplification of DNA extracted from MI hearts of mice given oral EcN revealed cardiac presence of translocated EcN. IHC analysis further confirmed presence of EcN in the heart. Siderophore-based PET imaging & radionuclide-based biodistribution studies revealed significantly higher uptake in the MI heart vs. Sham corroborating EcN presence. Immunoblotting revealed presence of GFP in cardiac tissue of MI mice suggesting that bacterial products and proteins could potentially translocate through the gut-heart axis. Conclusion: MI induced IH & myocardial hypoxia contribute to the translocation of gut bacteria and colonization of the ischemic heart.

Icariside II, a Naturally Occurring SIRT3 Agonist, Protects against Myocardial Infarction through the AMPK/PGC-1α/Apoptosis Signaling Pathway.

Myocardial infarction (MI) refers to the death of cardiomyocytes triggered by a lack of energy due to myocardial ischemia and hypoxia, and silent mating type information regulation 2 homolog 3 (SIRT3) plays an essential role in protecting against myocardial oxidative stress and apoptosis, which are deemed to be the principal causes of MI. Icariside II (ICS II), one of the main active ingredients of Herbal Epimedii, possesses extensive pharmacological activities. However, whether ICS II can protect against MI is still unknown. Therefore, this study was designed to investigate the effect and possible underlying mechanism of ICS II on MI both in vivo and in vitro. The results showed that pretreatment with ICS II not only dramatically mitigated MI-induced myocardial damage in mice but also alleviated H9c2 cardiomyocyte injury elicited by oxygen and glucose deprivation (OGD), which were achieved by suppressing mitochondrial oxidative stress and apoptosis. Furthermore, ICS II elevated the phosphorylation level of adenosine monophosphate-activated protein kinase (AMPK) and peroxisome proliferator-activated receptor-gamma coactivator 1 alpha (PGC-1α) expression, thereby activating SIRT3. However, these protective effects of ICS II on MI injury were largely abolished in SIRT3-deficient mice, manifesting that ICS II-mediated cardioprotective effects are, at least partly, due to the presence of SIRT3. Most interestingly, ICS II directly bound with SIRT3, as reflected by molecular docking, which indicated that SIRT3 might be a promising therapeutic target for ICS II-elicited cardioprotection in MI. In conclusion, our findings illustrate that ICS II protects against MI-induced oxidative injury and apoptosis by targeting SIRT3 through regulating the AMPK/PGC-1α pathway.

Wnt 3a Protects Myocardial Injury in Elderly Acute Myocardial Infarction by Inhibiting Serum Cystatin C/ROS-Induced Mitochondrial Damage

Aging represents an independent risk factor affecting the poor prognosis of patients with acute myocardial infarction (AMI). This present research aimed to explore the molecular mechanism of myocardial injury in elderly AMI by animals and cells experiment. Our previous clinical study found the serum Cystatin C (Cys-C) increased in the elderly AMI population, while the mechanism underlying high Cys-C induced myocardial injury of AMI remains unclear. In the in-vitro study, we confirmed that Wnt/β-catenin could significantly reduce the expression of cytoplasmic Cys-C through transnuclear action, and highly attenuate the occurrence of mitochondrial oxidative stress injury induced via Cys-C/reactive oxygen species (ROS). Furthermore, the addition of exogenous Wnt3a and inhibition of Cys-C expression could effectively inhibit mitochondrial oxidative stress injury and relieve the acute myocardial hypoxia injury. These results indicate that Cys-C exerted damaging effects on the hypoxic aging cardiomyocyte through the ROS/mitochondrial signaling pathway. Inhibition of this pathway effectively reduced the apoptosis of aging cardiomyocytes. In the in-vivo study, we also explored the function of the Wnt/Cys-C pathway on the ischemic infarction heart. We confirmed that Wnt/β-catenin served as the upstream protective protein of this pathway, and the promotion of this pathway improved the cardiac structure and function of the elderly AMI mice effectively.

Comprehensive Analysis of circRNA-miRNA-mRNA Regulatory Network and Novel Potential Biomarkers in Acute Myocardial Infarction.

BackgroundCircular RNA (circRNA) plays an important role in the regulation of gene expression and the occurrence of human diseases. However, studies on the role of circRNA in acute myocardial infarction (AMI) are limited. This study was performed to explore novel circRNA-related regulatory networks in AMI, aiming to better understand the molecular mechanism of circRNAs involvement in AMI and provide basis for further scientific research and clinical decision-making.MethodsThe AMI-related microarray datasets GSE160717 (circRNA), GSE31568 (miRNA), GSE61741 (miRNA), and GSE24519 (mRNA) were obtained from the Gene Expression Omnibus (GEO) database. After differential expression analysis, the regulatory relationships between these DERNAs were identified by online databases circBank, circInteractome, miRDB, miRWalk, Targetscan, and then two circRNA-miRNA-mRNA regulatory networks were constructed. Differentially expressed genes (DEGs) in this network were selected followed by enrichment analysis and protein–protein interaction (PPI) analysis. Hub genes were identified using Cytohubba plug-in of Cytoscape software. Hub genes and hub gene-related miRNAs were used for receiver operating characteristic curve (ROC) analysis to identify potential biomarkers. The relative expression levels of these biomarkers were further assessed by GSE31568 (miRNA) and GSE66360 (mRNA). Finally, on the basis of the above analysis, myocardial hypoxia model was constructed to verify the expression of Hub genes and related circRNAs.ResultsA total of 83 DEcircRNAs, 109 CoDEmiRNAs and 1204 DEGs were significantly differentially expressed in these datasets. The up-regulated circRNAs and down-regulated circRNAs were used to construct a circRNA-miRNA-mRNA regulatory network respectively. These circRNA-related DEGs were mainly enriched in the terms of “FOXO signaling pathway,” “T cell receptor signaling pathway,” “MAPK signaling pathway,” “Insulin resistance,” “cAMP signaling pathway,” and “mTOR signaling pathway.” The top 10 hub genes ATP2B2, KCNA1, GRIN2A, SCN2B, GPM6A, CACNA1E, HDAC2, SRSF1, ANK2, and HNRNPA2B1 were identified from the PPI network. Hub genes GPM6A, SRSF1, ANK2 and hub gene-related circRNAs hsa_circ_0023461, hsa_circ_0004561, hsa_circ_0001147, hsa_circ_0004771, hsa_circ_0061276, and hsa_circ_0045519 were identified as potential biomarkers in AMI.ConclusionIn this study, the potential circRNAs associated with AMI were identified and two circRNA-miRNA-mRNA regulatory networks were constructed. This study explored the mechanism of circRNA involvement in AMI and provided new clues for the selection of new diagnostic markers and therapeutic targets for AMI.

Jujuboside A Ameliorates Myocardial Apoptosis and Inflammation in Rats with Coronary Heart Disease by Inhibiting PPAR-α Signaling Pathway.

Background Coronary heart disease (CHD) is a chronic disease caused by atherosclerosis (AS), which can cause myocardial ischemia, hypoxia, or necrosis, seriously threatening human health. There is an urgent need for effective treatments and drugs to reduce the various risk factors for coronary heart disease and relieve symptoms of angina pectoris and myocardial infarction in patients. Jujuboside A (JuA) is a triterpenoid saponin extracted from jujube seeds, which has various biological activities such as antioxidant, anti-inflammatory, antiapoptotic, and neuroprotective effects. We study the function of JuA in myocardial injury, dyslipidemia, and inflammation in the CHD rat model, to explore its potential mechanism of improving CHD. Methods A rat model of CHD was established by feeding a high-fat diet. The rats were randomly divided into 5 groups (n = 6): control group, CHD group, JuA 25 mg/kg group, JuA 50 mg/kg group, and JuA 75 mg/kg group. Echocardiography was used to detect the cardiac function parameters of rats in each group, and then, hematoxylin and eosin staining was used to assess the histopathological injury in myocardial tissues. Levels of blood lipids, myocardial injury indexes, and inflammatory factors of rats in each group were measured by biochemical tests and enzyme linked immunosorbent assay, and the levels of Bax, Bcl-2, c-caspase-3, PPAR-α, p65, p-p65, IκBα, and p-IκBα protein expression in myocardial tissues were detected by western blot. Results Compared with the CHD group, JuA therapy significantly improved injury in myocardial tissue and endothelial tissue. It also strengthened cardiac function, while decreasing total cholesterol, triacylglycerol, and low-density lipoprotein cholesterol levels in the serum and increasing high-density lipoprotein cholesterol levels. In addition, JuA also restrained cardiomyocytes apoptosis and inhibited the inflammatory reaction by reducing TNF-α, IL-1β, and IL-6 expression in myocardial tissues. Furthermore, administration of JuA inhibited the activation of PPAR-α pathway by preventing the phosphorylation of p65 and IκBα in myocardial tissues of CHD rats. Conclusion JuA may improve cardiac function, alleviate myocardial and endothelial injury, and also ameliorate dyslipidemia and inflammatory reaction in rats with CHD, where JuA probably plays a protective role by inhibiting the activation of PPAR-α pathway.

Effects of NRF-1 and PGC-1α cooperation on HIF-1α and rat cardiomyocyte apoptosis under hypoxia

BackgroundHypoxia is a primary inducer of cardiomyocyte injury, its significant marker being hypoxia-induced cardiomyocyte apoptosis. Nuclear respiratory factor-1 (NRF-1) and hypoxia-inducible factor-1α (HIF-1α) are transcriptional regulatory elements implicated in multiple biological functions, including oxidative stress response. However, their roles in hypoxia-induced cardiomyocyte apoptosis remain unknown. The effect HIF-1α, together with NRF-1, exerts on cardiomyocyte apoptosis also remains unclear. MethodsWe established a myocardial hypoxia model and investigated the effects of these proteins on the proliferation and apoptosis of rat cardiomyocytes (H9C2) under hypoxia. Further, we examined the association between NRF-1 and HIF-1α to improve the current understanding of NRF-1 anti-apoptotic mechanisms. ResultsThe results show that NRF-1 and HIF-1α are important anti-apoptotic molecules in H9C2 cells under hypoxia, although their regulatory mechanisms differ. NRF-1 could bind to the promoter region of Hif1a and negatively regulate its expression. Additionally, HIF-1β exhibited competitive binding with NRF-1 and HIF-1α, demonstrating a synergism between NRF-1 and the peroxisome proliferator-activated receptor-gamma coactivator-1α. ConclusionThese results indicate that cardiomyocytes can regulate different molecular patterns to tolerate hypoxia, providing a novel methodological framework for studying cardiomyocyte apoptosis under hypoxia.

Role of circRNA circ_0000080 in myocardial hypoxia injury

ABSTRACT This study aimed to investigate the potential role of circRNA circ_0000080 in myocardial hypoxia injury and the underlying mechanisms. Patients with myocardial hypoxia injury who were admitted to Xi’an No. 1 Hospital, China, were included in this study. The expression levels of circ_0000080, miR-367-5p, and COX2 were analyzed by real-time quantitative PCR (RT-qPCR); cell viability was measured by cell counting kit-8 (CCK-8) assay; and apoptosis was detected by flow cytometry. In addition, the release of cytokines was determined by Enzyme-linked immunosorbent assay (ELISA), and the binding sites between miR-367-5p and circ_0000080/COX2 were predicted by bioinformatics analysis and confirmed by dual-luciferase reporter and RNA pull-down assays. circ_0000080 was upregulated in patients with MI and in H9c2 cells treated with H2O2 and hypoxia/reoxygenation (H/R). Silencing circ_0000080 reduced the H/R-mediated apoptosis of cardiomyocytes and secretion of pro-inflammatory cytokines. Moreover, circ_0000080 functioned as an miR-367-5p sponge to regulate the expression of COX2. Downregulated miR-367-5p or overexpressed COX2 degraded cellular functions of cardiomyocytes. circ_0000080 knockdown alleviated myocardial hypoxia injury through the miR-367-5p/COX2 axis.

Compound Danshen dripping pills in treating with coronary heart disease: A protocol for systematic review and meta-analysis.

Background:Coronary heart disease (CHD) patients are categorized by occlusion or vascular stenosis leading to myocardial ischemia, hypoxia, and necrosis. In clinical cardiovascular, CHD remains as a leading disease that is primarily prevalent among older people and mid-aged groups. CHD has a drastic impact on their life standard, and is known to have debilitating effects on both mental and physical wellbeing. As a Chinese patent medicine, compound Danshen dripping pills (CDDPs) are commonly administered to treat CHD in China. Despite the common intake of CDDPs, there is a lack of evidence-based clinical practice to inform its efficacy and safety through related systematic reviews. Therefore, the present protocol proposes to conduct a meta-analysis aiming to evaluate the effectivity and safeness of using CDDP for treating CHD patients.Methods:Randomized controlled trials that have evaluated the efficacy and safety of CDDP for treating CHD patients will be searched in MEDLINE, Cochrane Library, EMBASE, China National Knowledge Infrastructure, and WanFang databases. The search will include all related articles published till January 3, 2022. The extracted data will include information on study design, characteristics of the participants, details on intervention, and outcomes. Cochrane risk of bias tool will be employed to assess the quality of the trials. We will use either a random-effects model or fixed-effects model to pool the data. We will present the results as a risk ratio for dichotomous data and weighted mean difference for continuous data. We will visualize publication bias using funnel plots. Disagreements shall be resolved through discussion.Ethics and dissemination:Not required.OSF registration number:10.17605/OSF.IO/HJTP8

Metabolomic study on the protective effect of isoorientin against myocardial infarction

Myocardial infarction has become one of the largest threats to human life. Myocardial ischemia and hypoxia caused by myocardial infarction are important causes of myocardial cell injury. Compared with chemical drugs, botanical drugs that are natural antioxidants have relatively few toxic side effects. Isoorientin (ISO), a C-glucosyl flavone with a chemical nomenclature, exists in the human diet and has antioxidant and anti-inflammatory effects in other diseases. However, its role in myocardial infarction has not been reported. In this study, we investigated the effects of ISO administration on cardiac function in mice after myocardial infarction, on ROS levels in H9C2 myocardial cells after hypoxia in vitro, and on metabolomic changes in mice after myocardial infarction. We found that ISO improved cardiac function in mice after myocardial infarction and inhibited hypoxia-induced oxidative stress injury in H9C2 cells in vitro. We also found through metabolomic analysis and KEGG enrichment analysis that ISO significantly changed metabolic pathways in mice after myocardial infarction, including histidine metabolism, arachidonic acid metabolism, renin secretion and other pathways. These results lay a foundation for further exploration of the protective effect of ISO against myocardial infarction and the development of related drugs.

KLF2 regulates neutrophil activation and thrombosis in cardiac hypertrophy and heart failure progression.

It is widely recognized that inflammation plays a critical role in cardiac hypertrophy and heart failure. However, clinical trials targeting cytokines have shown equivocal effects, indicating the need for a deeper understanding of the precise role of inflammation and inflammatory cells in heart failure. Leukocytes from human subjects and a rodent model of heart failure were characterized by a marked reduction in expression of Klf2 mRNA. Using a mouse model of angiotensin II–induced nonischemic cardiac dysfunction, we showed that neutrophils played an essential role in the pathogenesis and progression of heart failure. Mechanistically, chronic angiotensin II infusion activated a neutrophil KLF2/NETosis pathway that triggered sporadic thrombosis in small myocardial vessels, leading to myocardial hypoxia, cell death, and hypertrophy. Conversely, targeting neutrophils, neutrophil extracellular traps (NETs), or thrombosis ameliorated these pathological changes and preserved cardiac dysfunction. KLF2 regulated neutrophil activation in response to angiotensin II at the molecular level, partly through crosstalk with HIF1 signaling. Taken together, our data implicate neutrophil-mediated immunothrombotic dysregulation as a critical pathogenic mechanism leading to cardiac hypertrophy and heart failure. This neutrophil KLF2-NETosis-thrombosis mechanism underlying chronic heart failure can be exploited for therapeutic gain by therapies targeting neutrophils, NETosis, or thrombosis.

Metabolic Variation Dictates Cardiac Pathogenesis in Patients With Tetralogy of Fallot.

BackgroundHerein, we aimed to analyze cardiac metabolic reprogramming in patients with tetralogy of Fallot (ToF).MethodsCardiac metabolic reprogramming was analyzed through comprehensive bioinformatics analysis, which included gene set enrichment, gene set variation, and consensus clustering analyses, so as to assess changes in metabolic pathways. In addition, full-spectrum metabolomics analysis was performed using right atrial biopsy samples obtained from patients with ToF and atrial septal defect (ASD) before cardiopulmonary bypass; ultrahigh performance liquid chromatography–tandem mass spectrometry (UPLC–MS/MS) was used to construct a metabolic map of cardiac metabolic reprogramming in cyanotic congenital heart disease.ResultsThe metabolic maps of carbohydrate metabolic process and heme metabolism were significantly activated, while bile acid metabolism, lipid droplet, and lipid binding were primarily restrained in ToF samples as compared with that in ASD samples. The reprogramming of butanoate metabolism was identified basing on the UPLC–MS/MS detection and analysis in myocardial hypoxia damage in cyanotic heart disease. Finally, the butanoate metabolism–related hub regulators ALDH5A1 and EHHADH were identified and they were significantly downregulated in ToF samples.ConclusionsThe metabolic network of butanoate metabolism involved ALDH5A1 and EHHADH, which could contribute to myocardial tissue damage in cyanotic congenital heart of ToF. Our results provide further insights into the mechanisms underlying metabolic reprogramming in cyanotic congenital heart disease and could lead to the identification of potential therapeutic targets.