Effect of N-n-butyl haloperidol iodide on ROS/JNK/Egr-1 signaling in H9c2 cells after hypoxia/reoxygenation

In vivo toxic and lethal cardiorespiratory effects of a synthetic quaternary ammonium salt derivative of haloperidol in mice

BACKGROUND

To investigate the toxicity of N-n-butyl haloperidol iodide (F2), a quaternary ammonium salt derivative of haloperidol, in mice for potential therapeutic purposes.

METHODS

The acute median lethal dose (LD50) of F2 was determined using the Bliss method following intravenous administration in mice. Routine surface electrocardiograms (ECGs) and arterial blood pressures (aBPs) were recorded under general anesthesia in untreated and pharmacologically vagotomized mice injected with F2. Sublethal doses of F2 were tested for their effects on aBP, heart rate, and biochemical parameters such as lactate dehydrogenase (LDH), blood urea nitrogen (BUN), and serum lactate levels. Histopathological changes in the heart, lungs, liver, and kidneys were evaluated after F2 administration.

RESULTS

The acute LD50 of F2 was determined to be 5.11 mg/kg. A 10 mg/kg dose of F2 caused severe hypotension, second-degree atrioventricular block, progressive prolongation of Pmurr intervals, and death due to cardiac asystole. Similar ECG and aBP changes were observed in atropine-pretreated mice, indicating that cholinergic effects do not play a major role in F2-induced toxicity. Sublethal doses of F2 (1.2 and 2.4 mg/kg) caused dose-dependent decreases in aBP and increases in heart rate. F2 induced significant, dose-dependent increases in LDH, BUN, and serum lactate levels. Histopathological analysis revealed acute lung lesions at 10 mg/kg, with no significant changes observed in the heart, liver, or kidneys.

CONCLUSION

Acute intravenous injection of F2 exhibits dose-dependent cardiopulmonary toxicity, characterized by severe hypotension, arrhythmias, and biochemical changes. These findings highlight the potential risks of F2 and the need for further evaluation of its safety profile for therapeutic use.

N -N-Butyl Haloperidol Iodide Mitigates Myocardial Ischemia/Reperfusion Injury Through Activation of SIRT1-Nrf2 Signaling Loop

ABSTRACT

N -n-butyl haloperidol iodide (F 2 ), a derivative of haloperidol developed by our group, exhibits potent antioxidative properties and confers protection against cardiac ischemia/reperfusion (I/R) injury. The protective mechanisms by which F 2 ameliorates I/R injury remain obscure. The activation of nuclear factor erythroid 2-related factor 2 (Nrf2), a key transcription factor transactivating many antioxidative genes, also attenuates I/R-induced myocardial damage. The present study investigated whether the cardioprotective effect of F 2 depends on Nrf2 using a mouse heart I/R model. F 2 (0.1, 0.2 or 0.4 mg/kg) or vehicle was intravenously injected to mice 5 minutes before reperfusion. Systemic administration of 0.4 mg/kg F 2 led to a significant reduction in I/R injury, which was accompanied by enhanced activation of Nrf2 signaling. The cardioprotection conferred by F 2 was largely abrogated in Nrf2-deficient mice. Importantly, we found F 2 -induced activation of Nrf2 is silent information regulator of transcription 1 (SIRT1)-dependent, as pharmacologically inhibiting SIRT1 by the specific inhibitor EX527 blocked Nrf2 activation. Moreover, F 2 -upregulated expression of SIRT1 was also Nrf2-dependent, as Nrf2 deficiency inhibited SIRT1 upregulation. These results indicate that SIRT1-Nrf2 signaling loop activation is indispensable for the protective effect of F 2 against myocardial I/R injury and may provide new insights for the treatment of ischemic heart disease.

Early Growth Response 1 Contributes to Renal IR Injury by Inducing Proximal Tubular Cell Apoptosis

Renal ischemia-reperfusion (IR) causes acute kidney injury due to oxidative stress, tubular inflammation, and apoptosis. Early growth response 1 (Egr-1) is a transcription factor belonging to the immediate early gene family and is known to regulate cell proliferation, differentiation, and survival. Egr-1 expression is induced during renal IR; however, its pathogenic role and underlying mechanisms remain elusive. Here, we investigated the function of Egr-1 during renal IR using C57BL/6 mice and cultured renal proximal tubular HK-2 cells. Egr-1 expression increased immediately, 1-4 h after IR, whereas plasma creatinine and oxidative stress increased progressively over 24 h after IR. Egr-1 overexpression showed greater increases in plasma creatinine, renal tubular injury, and apoptosis than in the control after IR. Egr-1 overexpression also showed significant neutrophil infiltration and increased pro-inflammatory cytokines (TNF-α, MIP-2, and IL-6) after IR. Consistently, proximal tubular HK-2 cells showed immediate induction of Egr-1 at 1 h after hypoxia and reoxygenation, where its downstream target, p53, was also increased. Interestingly, Egr-1 overexpression enhanced p53 levels and tubular apoptosis, while the knockdown of Egr-1 reduced p53 levels and tubular apoptosis after H2O2 treatment. Egr-1 was recruited to the p53 promoter, which activates p53 transcription, and Egr-1 induction occurred through Erk/JNK signaling kinases, as the specific inhibitors blocked its expression. Taken together, these results show that Egr-1 is upregulated in proximal tubular cells and contributes to renal IR injury by inducing tubular apoptosis, mediated by p53 transcriptional activation. Thus, Egr-1 could be a potential therapeutic target for renal IR injury.

Identification of TGF-β-related genes in cardiac hypertrophy and heart failure based on single cell RNA sequencing

BACKGROUND

Heart failure (HF) remains a huge medical burden worldwide. Pathological cardiac hypertrophy is one of the most significant phenotypes of HF. Several studies have reported that the TGF-β pathway plays a double-sided role in HF. Therefore, TGF-β-related genes (TRGs) may be potential therapeutic targets for cardiac hypertrophy and HF. However, the roles of TRGs in HF at the single-cell level remain unclear.

METHOD

In this study, to analyze the expression pattern of TRGs during the progress of cardiac hypertrophy and HF, we used three public single-cell RNA sequencing datasets for HF (GSE161470, GSE145154, and GSE161153), one HF transcriptome data (GSE57338), and one hypertrophic cardiomyopathy transcriptome data (GSE141910). Weighted gene co-expression network analysis (WGCNA), functional enrichment analysis and machine learning algorithms were used to filter hub genes. Transverse aortic constriction mice model, CCK-8, wound healing assay, quantitative real-time PCR and western blotting were used to validate bioinformatics results.

RESULTS

We observed that cardiac fibroblasts (CFs) and endothelial cells showed high TGF-β activity during the progress of HF. Three modules (royalblue, brown4, and darkturquoize) were identified to be significantly associated with TRGs in HF. Six hub genes (TANC2, ADAMTS2, DYNLL1, MRC2, EGR1, and OTUD1) showed anomaly trend in cardiac hypertrophy. We further validated the regulation of the TGF-β-MYC-ADAMTS2 axis on CFs activation in vitro.

CONCLUSIONS

This study identified six hub genes (TANC2, ADAMTS2, DYNLL1, MRC2, EGR1, and OTUD1) by integrating scRNA and transcriptome data. These six hub genes might be therapeutic targets for cardiac hypertrophy and HF.

JNK-dependent phosphorylation and nuclear translocation of EGR-1 promotes cardiomyocyte apoptosis

Myocardial apoptosis induced by myocardial ischemia and hyperlipemia are the main causes of high mortality of cardiovascular diseases. It is not clear whether there is a common mechanism responsible for these two kinds of cardiomyocyte apoptosis. Previous studies demonstrated that early growth response protein 1 (EGR-1) has a pro-apoptotic effect on cardiomyocytes under various stress conditions. Here, we found that EGR-1 is also involved in cardiomyocyte apoptosis induced by both ischemia and high-fat, but how EGR-1 enters the nucleus and whether nuclear EGR-1 (nEGR-1) has a universal effect on cardiomyocyte apoptosis are still unknown. By analyzing the phosphorylation sites and nucleation information of EGR-1, we constructed different mutant plasmids to confirm that the nucleus location of EGR-1 requires Ser501 phosphorylation and regulated by JNK. Furthermore, the pro-apoptotic effect of nEGR-1 was further explored through genetic methods. The results showed that EGR-1 positively regulates the mRNA levels of apoptosis-related proteins (ATF2, CTCF, HAND2, ELK1), which may be the downstream targets of EGR-1 to promote the cardiomyocyte apoptosis. Our research announced the universal pro-apoptotic function of nEGR-1 and explored the mechanism of its nucleus location in cardiomyocytes, providing a new target for the "homotherapy for heteropathy" to cardiovascular diseases.

N-n-Butyl haloperidol iodide ameliorates liver fibrosis and hepatic stellate cell activation in mice

N-n-Butyl haloperidol iodide (F₂) is a novel compound that has antiproliferative and antifibrogenic activities. In this study we investigated the therapeutic potential of F₂ against liver fibrosis in mice and the underlying mechanisms. Two widely used mouse models of fibrosis was established in mice by injection of either carbon tetrachloride (CCl₄) or thioacetamide (TAA). The mice received F₂ (0.75, 1.5 or 3 mg·kg^-1·d^-1, ip) for 4 weeks of fibrosis induction. We showed that F₂ administration dose-dependently ameliorated CCl₄- or TAA-induced liver fibrosis, evidenced by significant decreases in collagen deposition and c-Jun, TGF-β receptor II (TGFBR2), α-smooth muscle actin (α-SMA), and collagen I expression in the liver. In transforming growth factor beta 1 (TGF-β1)-stimulated LX-2 cells (a human hepatic stellate cell line) and primary mouse hepatic stellate cells, treatment with F₂ (0.1, 1, 10 μM) concentration-dependently inhibited the expression of α-SMA, and collagen I. In LX-2 cells, F₂ inhibited TGF-β/Smad signaling through reducing the levels of TGFBR2; pretreatment with LY2109761 (TGF-β signaling inhibitor) or SP600125 (c-Jun signaling inhibitor) markedly inhibited TGF-β1-induced induction of α-SMA and collagen I. Knockdown of c-Jun decreased TGF-β signaling genes, including TGFBR2 levels. We revealed that c-Jun was bound to the TGFBR2 promoter, whereas F₂ suppressed the binding of c-Jun to the TGFBR2 promoter to restrain TGF-β signaling and inhibit α-SMA and collagen I upregulation. In conclusion, the therapeutic benefit of F₂ against liver fibrosis results from inhibition of c-Jun expression to reduce TGFBR2 and concomitant reduction of the responsiveness of hepatic stellate cells to TGF-β1. F₂ may thus be a potentially new effective pharmacotherapy for human liver fibrosis.

The Egr-1/miR-15a-5p/GPX4 axis regulates ferroptosis in acute myocardial infarction

Acute myocardial infarction (AMI) is a type of cardiovascular diseases that severely threatens human being, but the mechanisms have not been thoroughly clarified. Here, we detected that microRNA-15a-5p (miR-15a-5p) was up-regulated in AMI. Knockdown of miR-15a-5p reduced cell mortality in hypoxic-treated myocardial cells. In addition, we determined that glutathione peroxidase4 (GPX4) was the direct target of miR-15a-5p by luciferase reporter assay. Over-expression of miR-15a-5p strengthened ferroptosis, then aggravated myocardial cell hypoxia injury. Mechanistically, silencing transcription factor early growth response-1 (Egr-1) inhibited the level of miR-15a-5p, increased the protein expression of GPX4, accompanied by reduced ferroptosis and alleviated myocardial injury. In summary, these results provide a novel signaling pathway during the progression of acute myocardial infarction, namely Egr-1/miR-15a-5p/GPX4/ferroptosis.

Versatile Nanoplatforms with enhanced Photodynamic Therapy: Designs and Applications

As an emerging antitumor strategy, photodynamic therapy (PDT) has attracted intensive attention for the treatment of various malignant tumors owing to its noninvasive nature and high spatial selectivity in recent years. However, the therapeutic effect is unsatisfactory on some occasions due to the presence of some unfavorable factors including nonspecific accumulation of PS towards malignant tissues, the lack of endogenous oxygen in tumors, as well as the limited light penetration depth, further hampering practical application. To circumvent these limitations and improve real utilization efficiency, various enhanced strategies have been developed and explored during the past years. In this review, we give an overview of the state-of-the-art advances progress on versatile nanoplatforms for enhanced PDT considering the enhancement from targeting or responsive, chemical and physical effect. Specifically, these effects mainly include organelle-targeting function, tumor microenvironment responsive release photosensitizers (PS), self-sufficient O2 (affinity oxygen and generating oxygen), photocatalytic water splitting, X-rays light stimulate, surface plasmon resonance enhancement, and the improvement by resonance energy transfer. When utilizing these strategies to improve the therapeutic effect, the advantages and limitations are addressed. Finally, the challenges and prospective will be discussed and demonstrated for the future development of advanced PDT with enhanced efficacy.

Glycyrrhizic acid exerts protective effects against hypoxia/reoxygenation-induced human coronary artery endothelial cell damage by regulating mitochondria

Hypoxia/reoxygenation (H/R) is one of the main causes of coronary artery disease (CAD), which is primarily induced by damage to coronary artery endothelial cells (CAECs). Glycyrrhizic acid (GA) is a natural and abundant pentacyclic triterpenoid glycoside of the licorice root extract, and it has been reported to elicit protective effects against hypoxia, inflammation and apoptosis in ischemic myocardium; therefore, GA may serve as a promising therapeutic agent for ischemia-associated CAD. In the present study, the protective effects of GA against H/R-induced injury in CAECs were investigated. Treatment with GA during H/R maintained cell viability and decreased H/R-induced cell apoptosis in human CAECs. In addition, H/R-mediated induction of intracellular and mitochondrial reactive oxygen species (ROS) was significantly decreased by GA exposure. Similar to ROS scavengers, GA treatment not only exhibited protective effects, but also maintained the mitochondrial membrane potential after H/R and inhibited H/R-induced mitochondrial dysfunction, including deficits in ATP synthesis, mitochondrial DNA copy number and mitochondrial transcriptional activity. Furthermore, GA decreased autophagy/mitophagy, and its protective effect against H/R was abolished by autophagy promotion. Collectively, the results suggested that GA exhibited protective effects against H/R-induced CAEC injury by decreasing ROS accumulation and maintaining mitochondrial homeostasis. Further investigation into the precise mechanisms underlying the decrease in ROS accumulation induced by GA is required.

miR-200a mediates protection of thymosin β-4 in cardiac microvascular endothelial cells as a novel mechanism under hypoxia-reoxygenation injury

Thymosin β-4 (Tβ4) is a ubiquitous protein, which has been suggested to regulate multiple cell signal pathways and a variety of cellular functions. However, the role Tβ4 plays in the cardiac microvascular endothelial cells (CMECs) under myocardial ischemia/reperfusion injury is currently unknown. Here we investigated the effects of Tβ4 on hypoxia/reoxygenation (H/R) induced CMECs injury and its potential molecular mechanism. Cultured CMECs were positively identified by flow cytometry using antibody against CD31 and VWF/Factor VIII, which are constitutively expressed on the surface of CMECs. Then the reduced level of Tβ4 was detected in H/R-CMECs by a real-time quantitative polymerase chain reaction. To determine the effects of Tβ4 on H/R-CMECs, we transfected the overexpression or silence vector of Tβ4 into CMECs under H/R condition. Our results indicated that H/R treatment could reduce proliferation, increased apoptosis, adhesion, and reactive oxygen species (ROS) production in CMECs, which were attenuated by Tβ4 overexpression or aggravated by Tβ4 silencing, implying Tβ4 is able to promote CMECs against H/R-induced cell injury. Furthermore, the microRNA-200a (miR-200a) level was also increased by Tβ4 in H/R-CMECs or reduced by Tβ4 small interfering RNA. To investigated the mechanism of protective effects of Tβ4 on CMECs injury, the miR-200a inhibitor was transfected into H/R-CMECs. The results indicated that inhibition of miR-200a inversed the protection of Tβ4 on H/R-CMECs, specifically including cell proliferation, cell adhesion, cell apoptosis, and ROS production, as well as nuclear factor erythroid 2-related factor 2 (Nrf2) nuclear translocation. In conclusion, our results determined that Tβ4 attenuated H/R-induced CMECs injury by miR-200a-Nrf2 signaling.

The cytoptrotection of small intestinal submucosa-derived gel in HL-1 cells during hypoxia/reoxygenation-induced injury

Small intestinal submucosa (SIS)-derived gel injected into infarcted myocardium has been shown to promote repair and regeneration after myocardial infarction (MI); however, the specific impact of SIS gel on cardiomyocytes remained unknown. The aim of this study was to characterise SIS gel function in hypoxia-reoxygenation (H/R)-induced cardiomyocyte damage and its potential mechanism. HL-1 cardiomyocytes seeded on SIS matrix-coated plates, SIS gel, and uncoated plates were subjected to H/R, cell viability, apoptosis, expression of caspase-3, Bcl-2, and Bax were investigated. SIS gel and SIS matrix as coating substrates markedly improved cell viability, preventing cell apoptosis compared with uncoated plates, with SIS gel yielding the best cytoprotective effects. SIS gel down-regulated expression of pro-inflammatory cytokines (TNF-α, CCL2, and IL-6) by inhibiting the JNK-mitogen-activated protein kinase (MAPK)/NF-κB pathways. Furthermore, SIS gel protected cardiomyocytes from apoptosis by activating protein kinase B (AKT) and extracellular-signal-regulated kinase (ERK) pathways, and markedly up-regulated antiapoptotic Bcl-2 expression but inhibited that of proapoptotic Bax and c-caspase 3. Together, these findings show that SIS gel could decrease H/R-induced cell apoptosis through a mechanism potentially related to its ability to regulate expression of inflammatory cytokines and antiapoptosis signalling pathways to prevent cell apoptosis. Our findings thereby shed light on the mechanism related to SIS gel therapeutic efficacy for MI.

N-n-Butyl Haloperidol Iodide Ameliorates Oxidative Stress in Mitochondria Induced by Hypoxia/Reoxygenation through the Mitochondrial c-Jun N-Terminal Kinase/Sab/Src/Reactive Oxygen Species Pathway in H9c2 Cells

Both c-Jun N-terminal kinase (JNK) and reactive oxygen species (ROS) play important roles in myocardial ischemia/reperfusion (I/R) injury. Our previous studies suggest that N-n-butyl haloperidol iodide (F2) exerts cardioprotection by reducing ROS production and JNK activation caused by I/R. In this study, we hypothesized that there is a JNK/Sab/Src/ROS pathway in the mitochondria in H9c2 cells following hypoxia/reoxygenation (H/R) that induces oxidative stress in the mitochondria and that F2 exerts mitochondrial protective effects during H/R injury by modulating this pathway. The results showed that H/R induced higher-level ROS in the cytoplasm on the one hand and JNK activation and translocation to the mitochondria by colocalization with Sab on the other. Moreover, H/R resulted in mitochondrial Src dephosphorylation, and subsequently, oxidative stress evidenced by the increase in ROS generation and oxidized cardiolipin in the mitochondrial membranes and by the decrease in mitochondrial superoxide dismutase activity and membrane potential. Furthermore, treatment with a JNK inhibitor or Sab small interfering RNA inhibited the mitochondrial translocation of p-JNK, decreased colocalization of p-JNK and Sab on the mitochondria, and reduced Src dephosphorylation and mitochondrial oxidative stress during H/R. In addition, Src dephosphorylation by inhibitor PP2 increased mitochondrial ROS production. F2, like inhibitors of the JNK/Sab/Src/ROS pathway, downregulated the H/R-induced mitochondrial translocation of p-JNK and the colocalization of p-JNK and Sab on the mitochondria, increased Src phosphorylation, and alleviated the above-mentioned mitochondrial oxidative stress. In conclusion, F2 could ameliorate H/R-associated oxidative stress in mitochondria in H9c2 cells through the mitochondrial JNK/Sab/Src/ROS pathway.

Self-nanomicellizing solid dispersion of edaravone: part I - oral bioavailability improvement

Background

Edaravone (EDR) is known for its free radical scavenging, antiapoptotic, antinecrotic, and anticytokine effects in neurological and non-neurological diseases. It is currently available clinically as Radicava^® and Radicut^®, intravenous medications, recently approved for the treatment of amyotrophic lateral sclerosis and cerebral infarction. However, the oral use of EDR is still restricted by its poor oral bioavailability (BA) due to poor aqueous solubility, stability, rapid metabolism, and low permeability. The present study reports the development of novel EDR formulation (NEF) using self-nanomicellizing solid dispersion (SNMSD) strategy with the aim to enable its oral use.

Materials and methods

The selection of a suitable carrier for the development of NEF was performed based on the miscibility study. The optimization of EDR-to-carrier ratio was conducted via kinetic solubility study after preparing SNMSDs using solvent evaporation technique. The drug–polymer carrier interaction and self-nanomicellizing properties of NEF were investigated with advanced characterization studies. In vitro permeation, metabolism, and dissolution study was carried out to examine the effect of the presence of a carrier on physico-chemical properties of EDR. Additionally, the dose-dependent pharmacokinetic study of NEF was conducted and compared with the EDR suspension.

Results

Soluplus^® (SOL) as a carrier was selected based on the potential for improving aqueous solubility. The NEF containing EDR and SOL (1:5) resulted in the highest enhancement in aqueous solubility (17.53-fold) due to amorphization, hydrogen bonding interaction, and micellization. Moreover, the NEF demonstrated significant improvement in metabolism, permeability, and dissolution profile of EDR. Furthermore, the oral BA of NEF showed 10.2-, 16.1-, and 14.8-fold enhancement compared to EDR suspension at 46, 138, and 414 µmol/kg doses.

Conclusion

The results demonstrated that SNMSD strategy could serve as a promising way to enhance EDR oral BA and NEF could be a potential candidate for the treatment of diseases in which oxidative stress plays a key role in their pathogenesis.

Panax ginseng Polysaccharide Protected H9c2 Cardiomyocyte From Hypoxia/Reoxygenation Injury Through Regulating Mitochondrial Metabolism and RISK Pathway

Background and Objective: Ischemic heart disease (IHD) has been the major issue of public health. Panax ginseng (ginseng) has been verified as an effective traditional Chinese medicines and exerted cardioprotective effect. This study aimed to investigate the polysaccharide fraction of ginseng on hypoxia/reoxygenation (H/R) injury in cardiomyocytes and the underlying mechanisms.

Methods: Ginseng was extracted by ethanol and fractionated by high-speed counter current chromatography (HSCCC) and column separation. The cardioprotective effect was evaluated in H9c2 cardiomyocytes underwent H/R treatment. The cell viability, apoptosis and mitochondrial respiration were examined.

Results: An acid polysaccharides fraction of ginseng (AP1) was identified the most effective fraction in protecting cardiomyocytes from H/R injury. AP1 restored the mitochondrial function by maintaining mitochondrial membrane potential (MMP), blocking the release of cytochrome C, and increasing the ATP generation and oxygen consumption rate (OCR) of cardiomyocytes. Meanwhile, AP1 induced the expression of glucocorticoid receptor (GR) and estrogen receptor (ER) which further activated reperfusion injury salvage kinase (RISK) pathway. Finally, AP1 increased nitric oxide (NO) production and regulated endothelial function by increasing endothelial NO synthase (eNOS) expression and decreasing inducible NOS (iNOS) expression in H/R injury.

Conclusion: The results suggested that AP1 exerted a protective effect in myocardial H/R injury mainly through maintaining myocardial mitochondrial function, thereby inhibiting myocardial H/R caused apoptosis and increasing the expressions of GR and ER, which in turn mediated the activation of RISK pathway and eNOS-dependent mechanism to resist the reperfusion injury.

A microfluidic-based lid device for conventional cell culture dishes to automatically control oxygen level

Most conventional hypoxic cell culture systems undergo reoxygenation during experimental manipulations, resulting in undesirable effects including the reduction of cell viability. A lid device was developed herein for conventional cell culture dishes to resolve this limitation. The integration of multilayered microfluidic channels inside a thin membrane was designed to prevent the reoxygenation caused by reagent infusion and automatically control the oxygen level. The experimental data clearly show the reducibility of the dissolved oxygen in the infusing reagent and the controllability of the oxygen level inside the dish. The feasibility of the device for hypoxia studies was confirmed by HIF-1α experiments. Therefore, the device could be used as a compact and convenient hypoxic cell culture system to prevent reoxygenation-related issues.

Ripk3 promotes ER stress-induced necroptosis in cardiac IR injury: A mechanism involving calcium overload/XO/ROS/mPTP pathway

Receptor-interacting protein 3 (Ripk3)-mediated necroptosis contributes to cardiac ischaemia-reperfusion (IR) injury through poorly defined mechanisms. Our results demonstrated that Ripk3 was strongly upregulated in murine hearts subjected to IR injury and cardiomyocytes treated with LPS and H₂O₂. The higher level of Ripk3 was positively correlated to the infarction area expansion, cardiac dysfunction and augmented cardiomyocytes necroptosis. Function study further illustrated that upregulated Ripk3 evoked the endoplasmic reticulum (ER) stress, which was accompanied with an increase in intracellular Ca²⁺ level ([Ca²⁺]c) and xanthine oxidase (XO) expression. Activated XO raised cellular reactive oxygen species (ROS) that mediated the mitochondrial permeability transition pore (mPTP) opening and cardiomyocytes necroptosis. By comparison, genetic ablation of Ripk3 abrogated the ER stress and thus blocked the [Ca²⁺]c overload-XO-ROS-mPTP pathways, favouring a pro-survival state that ultimately resulted in the inhibition of cardiomyocytes necroptosis in the setting of cardiac IR injury. In summary, the present study helps to elucidate how necroptosis is mediated by ER stress, via the calcium overload /XO/ROS/mPTP opening axis.

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ER stress is activated by Ripk3 in cardiac IR injury.

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ER stress induces calcium overload which triggers XO-dependent ROS overproduction.

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ROS outburst promotes mPTP opening that accounts for the necroptosis.

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Inhibiting ER stress favors cardiomyocytes survival and protects cardiac function.

N-n-Butyl Haloperidol Iodide, a Derivative of the Anti-psychotic Haloperidol, Antagonizes Hypoxia/Reoxygenation Injury by Inhibiting an Egr-1/ROS Positive Feedback Loop in H9c2 Cells

Early growth response-1 (Egr-1), a transcription factor which often underlies the molecular basis of myocardial ischemia/reperfusion (I/R) injury, and oxidative stress, is key to myocardial I/R injury. Silent information regulator of transcription 1(SIRT1) not only interacts with and is inhibited by Egr-1, but also downregulates reactive oxygen species (ROS) via the Forkhead box O1(FOXO1)/manganese superoxide dismutase (Mn-SOD) signaling pathway. N-n-butyl haloperidol iodide (F₂), a new patented compound, protects the myocardium against myocardial I/R injury in various animal I/R models in vivo and various heart-derived cell hypoxia/reoxygenation (H/R) models in vitro. In addition, F₂ can regulate the abnormal ROS/Egr-1 signaling pathway in cardiac microvascular endothelial cells (CMECs) and H9c2 cells after H/R. We studied whether there is an inverse Egr-1/ROS signaling pathway in H9c2 cells and whether the SIRT1/FOXO1/Mn-SOD signaling pathway mediates this. We verified a ROS/Egr-1 signaling loop in H9c2 cells during H/R and that F₂ protects against myocardial H/R injury by affecting SIRT1-related signaling pathways. Knockdown of Egr-1, by siRNA interference, reduced ROS generation, and alleviated oxidative stress injury induced by H/R, as shown by upregulated mitochondrial membrane potential, increased glutathione peroxidase (GSH-px) and total SOD anti-oxidative enzyme activity, and downregulated MDA. Decreases in FOXO1 protein expression and Mn-SOD activity occurred after H/R, but could be blocked by Egr-1 siRNA. F₂ treatment attenuated H/R-induced Egr-1 expression, ROS generation and other forms of oxidative stress injury such as MDA, and prevented H/R-induced decreases in FOXO1 and Mn-SOD activity_. Nuclear co-localization between Egr-1 and SIRT1 was increased by H/R and decreased by either Egr-1 siRNA or F₂. Therefore, our results suggest that Egr-1 inhibits the SIRT1/FOXO1/Mn-SOD antioxidant signaling pathway to increase ROS and perpetuate I/R injury. F₂ inhibits induction of Egr-1 by H/R, thereby activating SIRT1/FOXO1/Mn-SOD antioxidant signaling and decreasing H/R-induced ROS, demonstrating an important mechanism by which F₂ protects against myocardial H/R injury.

Egr-1 mediates leptin-induced PPARγ reduction and proliferation of pulmonary artery smooth muscle cells

Loss of peroxisome proliferator-activated receptor γ (PPARγ) has been found to contribute to pulmonary artery smooth muscle cell (PASMC) proliferation and pulmonary arterial remodeling therefore the development of pulmonary hypertension (PH). Yet, the molecular mechanisms underlying PPARγ reduction in PASMC remain poorly understood. Here, we demonstrated that leptin dose- and time-dependently inducued PPARγ down-regulation and proliferation of primary cultured rat PASMC, this was accompanied with the activation of extracellular regulated kinase1/2 (ERK1/2) signaling pathway and subsequent induction of early growth response-1 (Egr-1) expression. The presence of MEK inhibitors U0126 or PD98059, or prior silencing Egr-1 with small interfering RNA suppressed leptin-induced PPARγ reduction. In addition, activation of PPARγ by pioglitazone or targeting ERK1/2/Egr-1 suppressed leptin-induced PASMC proliferation. Taken together, our study indicates that ERK1/2 signaling pathway-mediated leptin-induced PPARγ reduction and PASMC proliferation through up-regulation of Egr-1 and suggests that targeting leptin/ERK1/2/Egr-1 pathway might have potential value in ameliorating vascular remodeling and benefit PH.

NLRP3 Inflammasome Activation-Mediated Pyroptosis Aggravates Myocardial Ischemia/Reperfusion Injury in Diabetic Rats

The reactive oxygen species- (ROS-) induced nod-like receptor protein-3 (NLRP3) inflammasome triggers sterile inflammatory responses and pyroptosis, which is a proinflammatory form of programmed cell death initiated by the activation of inflammatory caspases. NLRP3 inflammasome activation plays an important role in myocardial ischemia/reperfusion (MI/R) injury. Our present study investigated whether diabetes aggravated MI/R injury through NLRP3 inflammasome-mediated pyroptosis. Type 1 diabetic rat model was established by intraperitoneal injection of streptozotocin (60 mg/kg). MI/R was induced by ligating the left anterior descending artery (LAD) for 30 minutes followed by 2 h reperfusion. H9C2 cardiomyocytes were exposed to high glucose (HG, 30 mM) conditions and hypoxia/reoxygenation (H/R) stimulation. The myocardial infarct size, CK-MB, and LDH release in the diabetic rats subjected to MI/R were significantly higher than those in the nondiabetic rats, accompanied with increased NLRP3 inflammasome activation and increased pyroptosis. Inhibition of inflammasome activation with BAY11-7082 significantly decreased the MI/R injury. In vitro studies showed similar effects, as BAY11-7082 or the ROS scavenger N-acetylcysteine, attenuated HG and H/R-induced H9C2 cell injury. In conclusion, hyperglycaemia-induced NLRP3 inflammasome activation may be a ROS-dependent process in pyroptotic cell death, and NLRP3 inflammasome-induced pyroptosis aggravates MI/R injury in diabetic rats.

Compatibility of Tanshinone IIA and Astragaloside IV in attenuating hypoxia-induced cardiomyocytes injury

ETHNOPHARMACOLOGICAL RELEVANCE

Herbal medicines including Tanshinone IIA (TanIIA) and Astragaloside IV (AsIV) are widely used in Asia as therapeutic agents for cardiovascular diseases, due to their complementary roles and shared properties based on the theory of traditional Chinese medicine and pharmacological researches. However, the underlying pathological mechanisms for their efficacy are still unclear. In addition, the compatibility or incompatibility of the herbal medicines when administered with other herbal remedies or with prescription drugs is unknown.

AIM OF THE STUDY

We aimed to investigate the compatibility of TanIIA and AsIV in protecting cardiomyocytes against hypoxia-induced injury.

MATERIALS AND METHODS

Cultured cardiomyocytes were stimulated in hypoxia condition, in the absence or presence of the two herbal compounds, TanIIA and AsIV. Indicators were determined by cytotoxicity assay, quantitative PCR, ELISA, flow cytometry assay, immunofluorescence staining and western blot.

RESULTS

Either TanIIA alone or the combined herbal compounds inhibited hypoxia-triggered chemokines production including CCL2/5/19, CXCL2 and Transwell assay-indicated monocyte/macrophage recruitment, cytokines production including TNF-α and IL-6. While AsIV alone or the combined herbal compounds attenuated hypoxia-induced cell apoptosis indicated by decreased Annexin V⁺ cells and the ratio of Bax/Bcl-2, but no significant effect of the herbal compounds was observed in modulating cell apoptosis following both hypoxia and TNF-α stimulation. As an anti-apoptotic factor, stress granule formation was further enhanced by AsIV alone or the combined herbal compounds in hypoxia or heat shock stress. Moreover, immunoblotting analysis indicated that stress-responsive mitogen-activated protein kinases (MAPK) pathways including the phosphorylation of ERK1/2, p38 and JNK were inhibited while the phosphorylation of Akt in phosphatidylinositol 3-kinase (PI3K) -Akt pathway for cell survival was restored by the herbal compounds. Among these results, the combination of TanIIA and AsIV comprised most of the beneficial properties tested, although their combination did not improve the maximal effects achieved by any of the compounds alone.

CONCLUSIONS

Taken together, these data suggest a compatibility of TanIIA and AsIV in protecting cardiomyocyte against hypoxia-induced injury.

Emodin protects against oxidative stress and apoptosis in HK-2 renal tubular epithelial cells after hypoxia/reoxygenation

The aim of the present study was to determine the effects of emodin, a natural compound with antioxidant properties, on oxidative stress and apoptosis induced by hypoxia/reoxygenation (H/R) in HK-2 human renal tubular cells. In HK-2 cells subjected to H/R, it was observed that pre-treatment with emodin lead to an increase in cellular viability and a reduction in the rate of apoptosis and the B-cell lymphoma 2 (Bcl-2)-associated X protein/Bcl-2 ratio. H/R alone caused a significant increase in the levels of reactive oxygen species and malondialdehyde (P<0.05) and a significant decrease in the activities of superoxide dismutase, catalase and glutathione peroxidase (P<0.05), relative to normoxic cells. In turn, parameters of oxidative stress were improved by emodin pre-treatment. In addition, emodin pre-treatment significantly inhibited the phosphorylation of extracellular signal-regulated protein kinase and c-Jun N-terminal kinase mitogen-activated protein kinases (MAPKs) induced by H/R (P<0.05). These data suggest that emodin may prevent H/R-induced apoptosis in human renal tubular cells through the regulation of cellular oxidative stress, MAPK activation and restoration of the Bax/Bcl-2 ratio.

Age-associated up-regulation of EGR1 promotes granulosa cell apoptosis during follicle atresia in mice through the NF-κB pathway

Follicular atresia is the main process responsible for the loss of follicles and oocytes from the ovary, and it is the root cause of ovarian aging. Apoptosis of granulosa cells (GCs) is the cellular mechanism responsible for follicular atresia in mammals. Recent advances have highlighted fundamental roles for EGR1 in age-related diseases via the induction of apoptosis. In the present study, we found that the expression of EGR1 was significantly increased in aged mouse ovaries compared with young ovaries. Immunohistochemical analysis revealed strongly positive EGR1 staining in atretic follicles, especially in apoptotic granulosa cells. We further showed that EGR1 up-regulation in mouse primary granulosa cells inhibited cell proliferation and promoted apoptosis. In addition, the promotion of apoptosis in GCs by EGR1 increases over time and with reactive oxygen species (ROS) stimulation. Our mechanistic study suggested that EGR1 regulates GC apoptosis in a mitochondria-dependent manner and that this mainly occurs through the NF-κB signaling pathway. In conclusion, our results suggested that age-related up-regulation of EGR1 promotes GC apoptosis in follicle atresia during ovarian aging.

N-n-butyl haloperidol iodide ameliorates hypoxia/reoxygenation injury through modulating the LKB1/AMPK/ROS pathway in cardiac microvascular endothelial cells

Endothelial cells are highly sensitive to hypoxia and contribute to myocardial ischemia/reperfusion injury. We have reported that N-n-butyl haloperidol iodide (F2) can attenuate hypoxia/reoxygenation (H/R) injury in cardiac microvascular endothelial cells (CMECs). However, the molecular mechanisms remain unclear. Neonatal rat CMECs were isolated and subjected to H/R. Pretreatment of F2 leads to a reduction in H/R injury, as evidenced by increased cell viability, decreased lactate dehydrogenase (LDH) leakage and apoptosis, together with enhanced AMP-activated protein kinase (AMPK) and liver kinase B1 (LKB1) phosphorylation in H/R ECs. Blockade of AMPK with compound C reversed F2-induced inhibition of H/R injury, as evidenced by decreased cell viability, increased LDH release and apoptosis. Moreover, compound C also blocked the ability of F2 to reduce H/R-induced reactive oxygen species (ROS) generation. Supplementation with the ROS scavenger N-acetyl-L-cysteine (NAC) reduced ROS levels, increased cell survival rate, and decreased both LDH release and apoptosis after H/R. In conclusion, our data indicate that F2 may mitigate H/R injury by stimulating LKB1/AMPK signaling pathway and subsequent suppression of ROS production in CMECs.

Heme oxygenase 1 induction protects myocardiac cells against hypoxia/reoxygenation-induced apoptosis : The role of JNK/c-Jun/Caspase-3 inhibition and Akt signaling enhancement

BACKGROUND

Although recent studies have found that heme oxygenase (HO)-1 plays an important role in myocardiac cell survival, the precise mechanisms occurring during hypoxia/reoxygenation (H/R) injury remain unclear. Therefore, the aim of this study was to investigate the cytoprotective mechanisms of HO-1 against H/R-induced myocardiac cell apoptosis and to explore whether the Akt signaling pathway contributed to the protection provided by HO-1.

METHODS

Cobalt protoporphyrin (CoPP, a pharmacologic inducer of HO-1) was employed to induce the over-expression of HO-1 before H/R in H9c2 cells. Hoechst staining and flow cytometry were used to examine the extent of apoptosis. Furthermore, the effect of HO-1 on Akt, JNK, and the expression of apoptosis-related proteins (c-JUN and Caspase-3) was determined by Western blotting.

RESULTS

The results showed that over-expressed HO-1 could significantly protect myocardiac cells against H/R-induced apoptosis in H9c2 cells. Furthermore, the protein expression of p‑Akt increased and of p‑JNK decreased in the H/R injury H9c2 cells when treated with CoPP. The apoptosis-related proteins c‑Jun and caspase-3 were both inhibited by over-expression of HO-1. At the same time, retreatment with zinc protoporphyrin (ZnPP, a specific inhibitor of HO-1 enzymatic activity) or LY294002 (an inhibitor of Akt1) reversed the HO-1-induced changes.

CONCLUSION

In summary, our results suggest that HO-1 can decrease H/R-induced myocardiac cell apoptosis; the mechanism may be related to the activation of the Akt signaling pathway and, furthermore, to the inhibition of the JNK/c-Jun/caspase-3 signaling pathway.

The c-Jun N-terminal kinase (JNK) pathway is activated in human interstitial cystitis (IC) and rat protamine sulfate induced cystitis

The pathogenesis of bladder pain syndrome/interstitial cystitis (BPS/IC) is currently unclear. However, inflammation has been suggested to play an important role in BPS/IC. JNK downstream signaling plays an important role in numerous chronic inflammatory diseases. However, studies of the JNK pathway in BPS/IC are limited. In this study, we investigated the role of the JNK pathway in human BPS/IC and rat protamine sulfate (PS)-induced cystitis and examined the effect of the selective JNK inhibitor SP600125 on rat bladder cystitis. In our study, we demonstrated that the JNK signaling pathway was activated (the expression of JNK, c-Jun, p-JNK, p-c-Jun, IL-6 and TNF-α were significantly increasing in BPS/IC compared to the non-BPS/IC patients) and resulted in inflammation in human BPS/IC. Further animal models showed that the JNK pathway played an important role in the pathogenesis of cystitis. JNK inhibitors, SP600125, effectively inhibited the expression of p-JNK, p-c-Jun, IL-6 and TNF-α. The inhibition of these pathways had a protective effect on PS-induced rat cystitis by significantly decreasing histological score and mast cell count and improving bladder micturition function (micturition frequency significantly decreasing and bladder capacity significantly increasing). Therefore, JNK inhibition could be used as a potential treatment for BPS/IC.

Dissolved oxygen concentration in the medium during cell culture: Defects and improvements

In vitro cell culture has provided a useful model to study the effects of oxygen on cellular behavior. However, it remains unknown whether the in vitro operations themselves affect the medium oxygen levels and the living states of cells. In addition, a prevailing controversy is whether reactive oxygen species (ROS) production is induced by continuous hypoxia or reoxygenation. In this study, we have measured the effects of different types of cell culture containers and the oxygen environment where medium replacement takes place on the actual oxygen tension in the medium. We found that the deviations of oxygen concentrations in the medium are much greater in 25-cm(2) flasks than in 24-well plates and 35-mm dishes. The dissolved oxygen concentrations in the medium were increased after medium replacement in normoxia, but remained unchanged in glove boxes in which the oxygen tension remained at a low level (11.4, 5.7, and 0.5% O2 ). We also found that medium replacement in normoxia increased the number of ROS-positive cells and reduced the cell viability; meanwhile, medium replacement in a glove box did not produce the above effects. Therefore, we conclude that the use of 25-cm(2) flasks should be avoided and demonstrate that continuous hypoxia does not produce ROS, whereas the reoxygenation that occurs during the harvesting of cells leads to ROS and induces cell death.

N-n-butyl Haloperidol Iodide Protects against Hypoxia/Reoxygenation Injury in Cardiac Microvascular Endothelial Cells by Regulating the ROS/MAPK/Egr-1 Pathway

Endothelium dysfunction induced by reactive oxygen species (ROS) is an important initial event at the onset of myocardial ischemia/reperfusion in which the Egr-1 transcription factor often serves as a master switch for various damage pathways following reperfusion injury. We hypothesized that an intracellular ROS/MAPK/Egr-1 signaling pathway is activated in cardiac microvascular endothelial cells (CMECs) following hypoxia/reoxygenation (H/R). ROS generation, by either H/R or the ROS donor xanthine oxidase-hypoxanthine (XO/HX) activated all three MAPKs (ERK1/2, JNK, p38), and induced Egr-1 expression and Egr-1 DNA-binding activity in CMECs, whereas ROS scavengers (EDA and NAC) had the opposite effect following H/R. Inhibitors of all three MAPKs individually inhibited induction of Egr-1 expression by H/R in CMECs. Moreover, N-n-butyl haloperidol (F₂), previously shown to protect cardiomyocytes subjected to I/R, dose-dependently downregulated H/R-induced ROS generation, MAPK activation, and Egr-1 expression and activity in CMECs, whereas XO/HX and MAPK activators (EGF, anisomycin) antagonized the effects of F₂. Inhibition of the ROS/MAPK/Egr-1 signaling pathway, by either F₂, NAC, or inhibition of MAPK, increased CMEC viability and the GSH/GSSG ratio, and decreased Egr-1 nuclear translocation. These results show that the ROS/MAPK/Egr-1 signaling pathway mediates H/R injury in CMECs, and F₂ blocks this pathway to protect against H/R injury and further alleviate myocardial I/R injury.

Mitochondrial permeability transition triggers the release of mtDNA fragments

Fragments of mitochondrial DNA are released from mitochondria upon opening of the mitochondrial permeability transition pore. Cyclosporin A, an inhibitor of pore opening, completely prevented the release of mitochondrial fragments. Induction of mitochondrial permeability transition and subsequent release of the fragments of mitochondrial DNA could be one cause of genomic instability in the cell.