Effect of aortic smooth muscle BK channels on mediating chronic intermittent hypoxia-induced vascular dysfunction.

Chronic intermittent hypoxia (CIH) can lead to vascular dysfunction and increase the risk of cardiovascular diseases, cerebrovascular diseases, and arterial diseases. Nevertheless, mechanisms underlying CIH-induced vascular dysfunction remain unclear. Herein, this study analyzed the role of aortic smooth muscle calciumactivated potassium (BK) channels in CIH-induced vascular dysfunction. CIH models were established in rats and rat aortic smooth muscle cells (RASMCs). Hemodynamic parameters such as mean blood pressure (MBP), diastolic blood pressure (DBP), and systolic blood pressure (SBP) were measured in rats, along with an assessment of vascular tone. NO and ET-1 levels were detected in rat serum, and the levels of ET-1, NO, eNOS, p-eNOS, oxidative stress markers (ROS and MDA), and inflammatory factors (IL-6 and TNF-α) were tested in aortic tissues. The Ca2+ concentration in RASMCs was investigated. The activity of BK channels (BKα and BKß) was evaluated in aortic tissues and RASMCs. SBP, DBP, and MBP were elevated in CIH-treated rats, along with endothelial dysfunction, cellular edema and partial detachment of endothelial cells. BK channel activity was decreased in CIH-treated rats and RASMCs. BK channel activation increased eNOS, p-eNOS, and NO levels while lowering ET-1, ROS, MDA, IL-6, and TNF-α levels in CIH-treated rats. Ca2+ concentration increased in RASMCs following CIH modeling, which was reversed by BK channel activation. BK channel inhibitor (Iberiotoxin) exacerbated CIH-induced vascular disorders and endothelial dysfunction. BK channel activation promoted vasorelaxation while suppressing vascular endothelial dysfunction, inflammation, and oxidative stress, thereby indirectly improving CIH-induced vascular dysfunction.

Development and Validation of a Novel Prognostic Model Predicting the Atrial Fibrillation Recurrence Risk for Persistent Atrial Fibrillation Patients Treated with Nifekalant During the First Radiofrequency Catheter Ablation.

BACKGROUND: This study aimed to establish and assess a prediction model for patients with persistent atrial fibrillation (AF) treated with nifekalant during the first radiofrequency catheter ablation (RFCA). METHODS: In this study, 244 patients with persistent AF from January 17, 2017 to December 14, 2017, formed the derivation cohort, and 205 patients with persistent AF from December 15, 2017 to October 28, 2018, constituted the validation cohort. The least absolute shrinkage and selection operator regression was used for variable screening and the multivariable Cox survival model for nomogram development. The accuracy and discriminative capability of this predictive model were assessed according to discrimination (area under the curve [AUC]) and calibration. Clinical practical value was evaluated using decision curve analysis. RESULTS: Body mass index, AF duration, sex, left atrial diameter, and the different responses after nifekalant administration were identified as AF recurrence-associated factors, all of which were selected for the nomogram. In the development and validation cohorts, the AUC for predicting 1-year AF-free survival was 0.863 (95% confidence interval (CI) 0.801-0.926) and 0.855 (95% CI 0.782-0.929), respectively. The calibration curves showed satisfactory agreement between the actual AF-free survival and the nomogram prediction in the derivation and validation cohorts. In both groups, the prognostic score enabled stratifying the patients into different AF recurrence risk groups. CONCLUSIONS: This predictive nomogram can serve as a quantitative tool for estimating the 1-year AF recurrence risk for patients with persistent AF treated with nifekalant during the first RFCA.

CBL aggravates Ang II-induced cardiac hypertrophy via the VHL/HIF-1α pathway.

CBL (Casitas B cell lymphoma), an important ubiquitin protein ligase, is involved in protein folding, protein maturation, and proteasome-dependent protein catabolism in different cells. However, its role in cardiac hypertrophy is still unclear. In this study, we found that expression of CBL is increased in an Ang II-induced mouse cardiac hypertrophy animal model and in Ang II-treated H9C2 cells. Interference with CBL expression attenuates the degree of myocardial hypertrophy as well as the expression of hypertrophy-related genes in H9C2 cells. Further research found that CBL aggravates myocardial hypertrophy by activating HIF-1α, which is an aggravating factor for hypertrophy. The effect of CBL on promoting myocardial hypertrophy was reversed by interference with HIF-1α. Mechanistically, we found that CBL directly interacted with and degraded VHL by increasing its ubiquitination level, which is a widely accepted regulatory factor of HIF-1α. Finally, our results showed that CBL was partially dependent on degradation of VHL and that activation of HIF-1α promoted myocardial hypertrophy. Collectively, these findings suggest that strategies based on activation of the CBL/HIF-1α axis might be promising for the treatment of hypertrophic cardiomyopathy.

NOX4 aggravates doxorubicin-induced cardiomyocyte pyroptosis by increasing reactive oxygen species content and activating the NLRP3 inflammasome.

Background: Nicotinamide adenine dinucleotide phosphate oxidase 4 (NOX4)-mediated reactive oxygen species (ROS) has been reported to induce cardiomyocyte apoptosis, but its effect on pyroptosis of cardiomyocytes has been rarely reported. This paper aimed to explore the effects of NOX4-mediated ROS production on doxorubicin (DOX)-induced myocardial injury and pyroptosis through nucleotide-binding and oligomerization domain-like receptor protein 3 (NLRP3) inflammasome. Methods: HL-1 cells were treated with DOX or mice (30 mice were divided into five groups with six mice/group) underwent intraperitoneal injection with DOX (5 mg/kg, once a week, five times) to induce myocardial injury, followed by assessment of NOX4 and NLRP3 expression in cell supernatant and myocardial tissues. In cardiomyocyte HL-1 cells, cell proliferation was tested by MTT assay and the activity of ROS by probes. The superoxide dismutase (SOD) activity, malondialdehyde (MDA) content, and glutathione (GSH) activity were evaluated by kits. The expression of pyroptosis proteins was assessed by western blotting. Subsequently, the expression of NOX4 or NLRP3 was altered to determine the effect of NOX4 or NLRP3 expression on cardiomyocyte injury and pyroptosis. The animal models were utilized to evaluate the changes in the cardiac function of mice using an echocardiographic system, with these parameters measured including left ventricular ejection fraction (LVEF), left ventricular fractional shortening (LVFS), and left ventricular end-diastolic diameter (LVEDD). Furthermore, the content of myocardial injury markers and the protein expression of pyroptosis proteins were determined to evaluate myocardial injury in the mice. Results: DOX treatment led to cardiomyocyte injury and pyroptosis, as evidenced by weakened LVEF, LVFS, and cell proliferation (P<0.05), elevated LVEDD, ROS, and MDA (P<0.05), increased expression of pyroptosis proteins (P<0.05), and decreased SOD and GSH (P<0.05). Additionally, NOX4 and NLRP3 were highly-expressed (P<0.05) in cell supernatant and myocardial tissues. In DOX-induced HL-1 cells, the overexpression of NOX4 intensified ROS levels to aggravate cardiomyocyte injury and pyroptosis, which was reversed by treatment of the ROS scavenger N-acetyl-cysteine. Furthermore, it was revealed that the combination of short hairpin RNA (sh)-NOX4 and overexpressed (oe)-NLRP3 reversed the cardioprotective effects of sh-NOX4 and increased myocardial tissue or cell injury and pyroptosis in vitro and in vivo. No mice died during the animal experiments, and only two were ruled out due to a weight loss greater than 20%. Conclusions: NOX4-mediated ROS production activated NLRP3 inflammasome, thereby aggravating DOX-induced myocardial injury in vitro and in vivo.

The protective effect of Ghrelin peptide on doxorubicin hydrochloride induced heart failure in rats.

BACKGROUND: To investigate the protective effect and mechanism of Ghrelin on Doxorubicin (Dox) hydrochloride induced heart failure (HF) and myocardial injury in rats. METHODS: 45 rats were randomly divided into control group, HF group and Ghrelin group. Dox hydrochloride was injected intraperitoneally to establish the model of HF in rats of HF group and Ghrelin group. Rats in the Ghrelin group were given intraperitoneal injection of Ghrelin twice a day, and rats in the HF group and control group were given equal volume of normal saline for a total of 6 weeks. The changes of echocardiography, cardiac hemodynamics, myocardial histology and plasma inflammatory factors were observed. RESULTS: After the Ghrelin intervention, compared with the HF group, the left ventricular end-diastolic diameter (LVDD) and left ventricular end-systolic diameter (LVSD) in the Ghrelin group was markedly reduced (P < 0.05), and left ventricular ejection fraction (LVEF) was significantly increased (P < 0.05). Compared with HF group, the left ventricular systolic pressure (LVSP), maximum rate of increase in left ventricular pressure (+ dP/dtmax) and maximum rate of decrease in left ventricular pressure (- dP/dtmax) of Ghrelin group was remarkedly increased (P < 0.05), left ventricular diastolic pressure (LVDP) decreased (P < 0.05). In the Ghrelin group, the degree and extent of cardiomyocyte degeneration and necrosis were remarkedly reduced compared with the HF group. The levels of TNF-α and iNOS in Ghrelin group were notably lower than those in HF group (P < 0.05), the IL-10 level increased markedly (P < 0.05). CONCLUSION: Ghrelin may reduce Dox-induced myocardial injury and improve cardiac function in rats by regulating inflammation and oxidative stress.

Circ-0006332 stimulates cardiomyocyte pyroptosis via the miR-143/TLR2 axis to promote doxorubicin-induced cardiac damage.

Doxorubicin (DOX)-mediated cardiotoxicity can impair the clinical efficacy of chemotherapy, leading to heart failure (HF). Given the importance of circRNAs and miRNAs in HF, this paper intended to delineate the mechanism of the circular RNA 0006332 (circ -0,006,332)/microRNA (miR)-143/Toll-like receptor 2 (TLR2) axis in doxorubicin (DOX)-induced HF. The binding of miR-143 to circ -0,006,332 and TLR2 was assessed with the dual-luciferase assay, and the binding between miR-143 and circ -0,006,332 was determined with FISH, RIP, and RNA pull-down assays. miR-143 and/or circ -0,006,332 were overexpressed in rats and cardiomyocytes, followed by DOX treatment. In cardiomyocytes, miR-143 and TLR2 expression, cell viability, LDH release, ATP contents, and levels of IL-1ß, IL-18, TNF-α, and pyroptosis-related molecules were examined. In rats, cardiac function, serum levels of cardiac enzymes, apoptosis, myocardial fibrosis, and levels of IL-1ß, IL-18, TNF-α, TLR2, and pyroptosis-related molecules were detected. miR-143 diminished TLR2 expression by binding to TLR2, and circ -0,006,332 bound to miR-143 to downregulate miR-143 expression. miR-143 expression was reduced and TLR2 expression was augmented in DOX-induced cardiomyocytes. miR-143 inhibited DOX-induced cytotoxicity by suppressing pyroptosis in H9C2 cardiomyocytes. In DOX-induced rats, miR-143 reduced cardiac dysfunction, myocardial apoptosis, myocardial fibrosis, TLR2 levels, and pyroptosis. Furthermore, overexpression of circ -0,006,332 blocked these effects of miR-143 on DOX-induced cardiomyocytes and rats. Circ -0,006,332 stimulates cardiomyocyte pyroptosis by downregulating miR-143 and upregulating TLR2, thus promoting DOX-induced cardiac injury.

RNA methylation reading protein YTHDF2 relieves myocardial ischemia-reperfusion injury by downregulating BNIP3 via m6A modification.

BNIP3 is reported to be involved in hypoxia-induced mitochondrial defect and cell death in cardiomyocytes. However, little is known about the specific function and molecular mechanism of BNIP3-mediated mitophagy in myocardial ischemia-reperfusion injury (MIRI). Herein, this study explored the mechanism regulating BNIP3-modulated mitophagy in MIRI. Rat cardiomyocytes (H9c2 cells) underwent transfection and hypoxia/reoxygenation (H/R) treatment, followed by cell viability and apoptosis detection. Gain-of-function assays were conducted in rats before MIRI modeling, followed by the monitoring of cardiac changes and the evaluation of cardiac function, myocardial infarction area, and apoptosis in myocardial tissues. The levels of creatine kinase MB (CK-MB), cardiac troponin I (cTnI), lactic dehydrogenase (LDH), reactive oxygen species (ROS), malondialdehyde (MDA), superoxide dismutase (SOD), p62, and LC3 II/LC3 I were tested in rat serum or H9c2 cells. The co-localization of LC3 and TOMM20 was analyzed. The interaction of BNIP3 with YTHDF2 was assessed. H/R treatment decreased cell viability and p62 and SOD levels while elevating cell apoptosis, the levels of CK-MB, cTnI, LDH, MDA, ROS, and LC3 II/LC3 I, the number of autophagosomes, and the co-localization of LC3 and TOMM20 in cardiomyocytes, which were neutralized by downregulating BNIP3 or upregulating YTHDF2. Moreover, upregulation of YTHDF2 repressed myocardial injury and mitophagy in MIRI rats. Mechanistically, YTHDF2 mediated BNIP3 expression by recognizing methylated BNIP3. Upregulation of BNIP3 counteracted the suppressive effect of YTHDF2 overexpression on H/R-induced injury and mitophagy in cardiomyocytes. The RNA methylation reading protein YTHDF2 ameliorated MIRI by downregulating BNIP3 via m6A modification.

Bone marrow stromal cell-derived exosomes improve oxidative stress and pyroptosis in doxorubicin-induced myocardial injury in vitro by regulating the transcription of GSDMD through the PI3K-AKT-Foxo1 pathway.

OBJECTIVES: Doxorubicin (DOX) can contribute to severe myocardial injury, and bone marrow stromal cells (BMSC)-exosomes (Exos) improves acute myocardial infarction. Hence, this research investigated whether BMSC-Exos alleviated DOX-induced myocardial injury. METHODS: BMSC-derived Exos were isolated and identified, and the optimal concentration of DOX was confirmed. H9C2 cells were treated with DOX and BMSC-Exos or in combination with the protein kinase B (AKT) inhibitor. Reactive oxygen species (ROS) and JC-1 were detected to assess oxidative stress (OS) and mitochondrial membrane damage, respectively. In addition, the expression of pyroptosis-related molecules was measured. The expression of phosphatidylinositol 3 kinase (PI3K)-AKT pathway-related proteins and the phosphorylation and acetylation of forkhead box O1 (Foxo1) in the cell nucleus and cytoplasm were tested. Last, interactions between Foxo1 and gasdermin D (GSDMD) were assessed. RESULTS: BMSC-Exo treatment increased viability and mitochondrial membrane potential and reduced lactic dehydrogenase release and ROS levels in DOX-treated H9C2 cells. Furthermore, the addition of BMSC-Exos suppressed DOX-induced activation and upregulation of NLRP3 and apoptosis-associated speck-like protein containing A CARD (ASC) and in vitro cleavage of caspase-1, GSDMD, interleukin (IL)-1ß, and IL-18 proteins. Additionally, BMSC-Exo treatment enhanced the expression of phosphorylated (p)-PI3K, p-AKT, and p-mTOR in DOX-treated H9C2 cells and the levels of phosphorylated Foxo1 in the cytoplasm of DOX-treated H9C2 cells. Foxo1 was enriched in the promoter region of GSDMD. Moreover, the AKT inhibitor API-2 annulled the effects of BMSC-Exos on OS, pyroptosis, and Foxo1 phosphorylation in DOX-treated H9C2 cells. CONCLUSIONS: BMSC-Exos phosphorylated Foxo1 and inactivated Foxo1 transcription via the PI3K-AKT pathway to diminish GSDMD expression, thus restraining DOX-induced pyroptosis and OS of myocardial cells.

SIRT4 Suppresses Doxorubicin-Induced Cardiotoxicity by Regulating the AKT/mTOR/Autophagy Pathway.

Doxorubicin (DOX) is a potent anthracycline chemotherapeutic drug. DOX-induced cardiotoxicity (DIC) limits its application in cancer treatment, as this complication is detrimental and fatal. Reactive oxygen species (ROS) production, autophagic dysfunction and cell death are crucial factors related to DIC. Previous studies have shown that SIRT4 is associated with cardiac energy metabolism, cardiac mitochondrial dysfunction and cardiac cell death, but it is unclear whether SIRT4 affects DOX-induced cardiac injury. Our data suggested that SIRT4 overexpression in vivo and in vitro could alleviate DIC by improving cardiac function and reducing cardiomyocyte apoptosis and autophagy. However, autophagy activation by rapamycin abolished the protective effect of SIRT4 overexpression on DIC. Furthermore, in the context of DOX treatment, SIRT4 overexpression activated the Akt/mTOR signaling pathway and inhibited autophagy through the Akt/mTOR signaling pathway. Our findings indicate that SIRT4 overexpression protects against DIC by inhibiting Akt/mTOR-dependent autophagy. These findings may provide a prospective therapeutic target for DIC.

Transcriptional activation of ENPP2 by FoxO4 protects cardiomyocytes from doxorubicin­induced toxicity.

It has been shown that ferroptosis is involved in doxorubicin (DOX)­induced cardiotoxicity and that ectonucleotide pyrophosphatase/phosphodiesterase 2 (ENPP2) can protect cardiomyocytes from ferroptosis. Thus, the present study aimed to investigate whether ENPP2 could protect cardiomyocytes from DOX­induced injury by inhibiting ferroptosis. H9c2 cardiomyocytes were exposed to various concentrations (0.625, 1.25, 2.5, 5 or 10 µM) of DOX for different time periods. Cell viability and ENPP2 expression were determined. ENPP2­overexpressing H9c2 cells were treated with DOX and subsequently cell viability, oxidative stress, autophagy and ferroptosis were measured using the corresponding assays (MTT assay, commercial kits and western blot analysis). Dual­luciferase reporter and chromatin immunoprecipitation assays, as well as bioinformatics analysis, were applied to detect the interaction between ENPP2 and FoxO4. Following FoxO4 overexpression in H9c2 cells, the aforementioned cellular processes were assessed. The results indicated that ENPP2 expression was downregulated following treatment of the cells with DOX. DOX also led to the decreased cell viability, reduced autophagy and elevated ferroptosis in H9c2 cells, which were notably reversed by ENPP2 overexpression. In addition, FoxO4 bound to the ENPP2 promoter, resulting in inhibition of its expression. Following FoxO4 overexpression in H9c2 cells, further experiments conducted using commercial kits and western blot analysis revealed that FoxO4 overexpression partially inhibited the effects of ENPP2 overexpression on DOX­induced oxidative stress, autophagy and ferroptosis in H9c2 cells. In conclusion, the data indicated that ENPP2 was transcriptionally regulated by FoxO4 to protect cardiomyocytes from DOX­induced toxicity by inhibiting ferroptosis. Therefore, specific treatment approaches targeting the FoxO4/ENPP2 axis and ferroptosis may provide potential therapies for alleviating DOX­induced cardiotoxicity.

Ferroptosis Is a Potential Novel Diagnostic and Therapeutic Target for Patients With Cardiomyopathy.

Cardiomyocyte death is a fundamental progress in cardiomyopathy. However, the mechanism of triggering the death of myocardial cells remains unclear. Ferroptosis, which is the nonapoptotic, iron-dependent, and peroxidation-driven programmed cell death pathway, that is abundant and readily accessible, was not discovered until recently with a pharmacological approach. New researches have demonstrated the close relationship between ferroptosis and the development of many cardiovascular diseases, and several ferroptosis inhibitors, iron chelators, and small antioxidant molecules can relieve myocardial injury by blocking the ferroptosis pathways. Notably, ferroptosis is gradually being considered as an important cell death mechanism in the animal models with multiple cardiomyopathies. In this review, we will discuss the mechanism of ferroptosis and the important role of ferroptosis in cardiomyopathy with a special emphasis on the value of ferroptosis as a potential novel diagnostic and therapeutic target for patients suffering from cardiomyopathy in the future.

Identification of lncRNA NR_028138.1 as a biomarker and construction of a ceRNA network for bipolar disorder.

The pathogenesis of bipolar disorder (BD), a chronic mood disorder, is largely unknown. Noncoding RNAs play important roles in the pathogenesis of BD. However, little is known about the correlations of long noncoding RNAs (lncRNAs) with BD. Illumina high-throughput sequencing in BD patients and normal controls was used to identify differentially expressed (DE) genes. Two-step real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR) was used to validate DE-RNAs in the first cohort (50 BD and 50 control subjects). Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways and lncRNA-mRNA coexpression and lncRNA-microRNA (miRNA)-messenger RNA (mRNA) competing endogenous RNA (ceRNA) network analyses were used to predict the functions of DE-RNAs. Receiver operating characteristic (ROC) curve analysis and logistic regression were applied to evaluate diagnostic performance in an additional testing group (80 BD and 66 control subjects). A total of 576 significantly DE-lncRNAs and 262 DE-mRNAs were identified in BD patients, and 95 lncRNA-miRNA-mRNA interactions were used to construct a ceRNA regulatory network. Analysis of the first cohort showed that six RNAs (NR_028138.1, TCONS_00018621, TCONS_00002186, TNF, PID1, and SDK1) were differentially expressed in the BD group (P < 0.01). NR_028138.1 was used to establish a BD diagnostic model (area under the ROC curve 0.923, P < 0.004, 95% CI: 0.830-0.999). Verification in the second cohort revealed uniformly significant differences in NR_028138.1 (P < 0.0001). This study constructed a ceRNA regulatory network and provided a hypothesis for the pathogenesis of BD. NR_028138.1 was identified as a central element involved in the transcriptional regulation in BD and a potential biomarker.