Diabetes mellitus abrogates the cardioprotection of sufentanil against ischaemia/reperfusion injury by altering glycogen synthase kinase-3β

Sufentanil ameliorates oxygen‑glucose deprivation/reoxygenation‑induced endothelial barrier dysfunction in HCMECs via the PI3K/Akt signaling pathway

Ischemic heart disease, a chronic myocardial damage disease caused by coronary artery ischemia, is the leading cause of death worldwide. The aim of the present study was to explore the efficacy of sufentanil in myocardial ischemia/reperfusion (I/R) injury. Oxygen and glucose deprivation/reoxygenation (OGD/R) was utilized to induce human cardiac microvascular endothelial cells (HCMECs) to simulate myocardial I/R injury in vitro. The Cell Counting Kit-8 assay was used to detect the effects of sufentanil on HCMECs and OGD/R-induced HCMECs. The TUNEL, lactate dehydrogenase (LDH) activity, immunofluorescence and in vitro permeability assays, were used to assess apoptosis, LDH activity, VE-cadherin protein expression levels and endothelial barrier function in OGD/R-induced HCMECs, respectively. Moreover, western blotting was performed to assess the protein expression levels of apoptosis, endothelial barrier function and phosphatidylinositol-3-kinase (PI3K)/protein kinase B (Akt)-related proteins. The results demonstrated that sufentanil had no significant influence on the viability of HCMECs but increased the viability of OGD/R-induced HCMECs in a dose-dependent manner. Furthermore, sufentanil inhibited cell apoptosis and permeability of OGD/R-induced HCMECs but enhanced the protein expression levels of tight junction proteins, including ZO-1, Occludin, VE-cadherin and Claudin-5. Sufentanil was also demonstrated to activate the PI3K/Akt signaling pathway. In addition, the use of LY294002, an inhibitor of the PI3K/Akt signaling pathway, partially abolished the protective effects of sufentanil on apoptosis, permeability and tight junction protein expression levels. These results indicated that sufentanil ameliorated OGD/R-induced endothelial barrier dysfunction in HCMECs, potentially via the PI3K/Akt signaling pathway. The present study therefore suggested that sufentanil may serve as a novel therapeutic option for the improvement of myocardial I/R injury.

Chronic type 2 but not type 1 diabetes impairs myocardial ischaemic tolerance and preconditioning in C57Bl/6 mice

NEW FINDINGS

• What is the central question of this study? What is the impact of chronic adult-onset diabetes on cardiac ischaemic outcomes and preconditioning? • What is the main finding and its importance? Chronic adult-onset type 2 but not type 1 diabetes significantly impairs myocardial ischaemic tolerance and ischaemic preconditioning. Preconditioning may be detrimental in type 2 diabetes, exaggerating nitrosative stress and apoptotic protein expression.

ABSTRACT

Effects of diabetes on myocardial responses to ischaemia-reperfusion (I-R) and cardioprotective stimuli remain contentious, potentially reflecting influences of disease duration and time of onset. Chronic adult-onset type 1 diabetes (T1D) and type 2 diabetes (T2D) were modelled non-genetically in male C57Bl/6 mice via 5 × 50 mg kg^-1 daily streptozotocin (STZ) injections + 12 weeks' standard chow or 1 × 75 mg kg^-1 STZ injection + 12 weeks' obesogenic diet (32% calories as fat, 57% carbohydrate, 11% protein), respectively. Systemic outcomes were assessed and myocardial responses to I-R ± ischaemic preconditioning (IPC; 3 × 5 min I-R) determined in Langendorff perfused hearts. Uncontrolled T1D was characterised by pronounced hyperglycaemia (25 mm fasting glucose), glucose intolerance and ∼10% body weight loss, whereas T2D mice exhibited moderate hyperglycaemia (15 mm), hyperinsulinaemia, glucose intolerance and 17% weight gain. Circulating ghrelin, resistin and noradrenaline were unchanged with T1D, while leptin increased and noradrenaline declined in T2D mice. Ischaemic tolerance and IPC were preserved in T1D hearts. In contrast, T2D worsened post-ischaemic function (∼40% greater diastolic and contractile dysfunction) and cell death (100% higher troponin efflux), and abolished IPC protection. Whereas IPC reduced post-ischaemic nitrotyrosine and pro-apoptotic Bak and Bax levels in non-diabetic hearts, these effects were reduced in T1D and IPC augmented Bax and nitrosylation in T2D hearts. The data demonstrate chronic T1D does not inhibit myocardial I-R tolerance or IPC, whereas metabolic and endocrine disruption in T2D is associated with ischaemic intolerance and inhibition of IPC. Indeed, normally protective IPC may exaggerate damage mechanisms in T2D hearts.

HDAC3 Mediates Cardioprotection of Remifentanil Postconditioning by Targeting GSK-3β in H9c2 Cardiomyocytes in Hypoxia/Reoxygenation Injury

BACKGROUND

Remifentanil postconditioning (RPC) confers robust cardioprotection against ischemia/reperfusion (I/R) injury. We recently determined that HDAC3 was involved in RPC-induced cardioprotection. However, the role of HDAC3 and its possible mechanisms in RPC-induced cardioprotection are unknown, which we aimed to evaluate in an in vitro hypoxia/reoxygenation (HR) model.

METHODS

Myocardium I/R injury was established after HR with H9c2 cardiomyoblasts. Cell viability and apoptosis were evaluated usingCCK-8 and flow cytometry of HR-injured cardiomyoblasts treated with or without RPC. Furthermore, effects of RPC on HDAC3 protein and mRNA expression were evaluated with Western blot and quantitative real-time PCR analyses, whereas GSK-3β expression was measured with Western blot.

RESULTS

RPC increased cell viability and reduced cell apoptosis (P < 0.05) in H9c2 cardiomyoblasts subjected to HR injury. In addition, RPC promoted the phosphorylation of GSK-3β at Ser9 site (P < 0.05) and suppressed the protein and mRNA expression of HDAC3 (P < 0.05). Lentiviral-transduced overexpression of HDAC3 had no significant effects on HR injury while attenuating the cardioprotective effects of RPC on cell viability and apoptosis (P < 0.05), GSK-3β phosphorylation (P < 0.05) in H9c2 cardiomyoblasts.

CONCLUSIONS

RPC attenuates apoptosis in H9c2 cardiomyoblasts after HR injury by downregulating HDAC3-mediated phosphorylation of GSK-3β. Our findings suggest that HDAC3, and its cross talk function with GSK-3β, may be a promising target for myocardium I/R injury.

Hyperglycemia-Induced Oxidative Stress Abrogates Remifentanil Preconditioning-Mediated Cardioprotection in Diabetic Rats by Impairing Caveolin-3-Modulated PI3K/Akt and JAK2/STAT3 Signaling

Diabetic hearts are more vulnerable to ischemia/reperfusion (I/R) injury and less responsive to remifentanil preconditioning (RPC), but the underlying mechanisms are incompletely understood. Caveolin-3 (Cav-3), the dominant isoform of cardiomyocyte caveolae, is reduced in diabetic hearts in which oxidative stress is increased. This study determined whether the compromised RPC in diabetes was an independent manifestation of hyperglycemia-induced oxidative stress or linked to impaired Cav-3 expression with associated signaling abnormality. RPC significantly attenuated postischemic infarction, cardiac dysfunction, myocardial apoptosis, and 15-F2t-isoprostane production (a specific marker of oxidative stress), accompanied with increased Cav-3 expression and enhanced Akt and STAT3 activation in control but not in diabetic rats. Pretreatment with the antioxidant N-acetylcysteine (NAC) attenuated hyperglycemia-induced reduction of Cav-3 expression and Akt and STAT3 activation and restored RPC-mediated cardioprotection in diabetes, which was abolished by cardiac-specific knockdown of Cav-3 by AAV9-shRNA-Cav-3, PI3K/Akt inhibitor wortmannin, or JAK2/STAT3 inhibitor AG490, respectively. Similarly, NAC could restore RPC protection from high glucose and hypoxia/reoxygenation-induced injury evidenced by decreased levels of LDH release, 15-F2t-isoprostane, O₂ ^-, and JC-1 monomeric cells, which were reversed by caveolae disrupter methyl-β-cyclodextrin, wortmannin, or AG490 in isolated primary cardiomyocytes or siRNAs of Cav-3, Akt, or STAT3 in H9C2 cells. Either methyl-β-cyclodextrin or Cav-3 knockdown reduced Akt and STAT3 activation. Further, the inhibition of Akt activation by a selective inhibitor or siRNA reduced STAT3 activation and vice versa, but they had no effects on Cav-3 expression. Thus, hyperglycemia-induced oxidative stress abrogates RPC cardioprotection by impairing Cav-3-modulated PI3K/Akt and JAK2/STAT3 signaling. Antioxidant treatment with NAC could restore RPC-induced cardioprotection in diabetes by improving Cav-3-dependent Akt and STAT3 activation and by facilitating the cross talk between PI3K/Akt and JAK2/STAT3 signaling pathways.

New advances in perioperative cardioprotection

With the increasing age of the general population, medical conditions necessitating a surgical intervention will increase. Concomitant with advanced age, the prevalence of type 2 diabetes mellitus will also increase. These patients have a two- to three-fold higher risk of occurrence of cardiovascular events and are at higher risk of perioperative myocardial ischemia. This review will discuss recent advances in the field of perioperative cardioprotection and focus specifically on strategies that have aimed to protect the diabetic and the aged myocardium. This review will not deal with potential putative cardioprotective effects of opioids and anesthetic agents, as this is a very broad area that would necessitate a dedicated overview.

By regulating miR-182-5p/BCL10/CYCS, sufentanil reduces the apoptosis of umbilical cord mesenchymal stem cells caused by ropivacaine

Sufentanil is a type of opioid analgesic and is usually used to facilitate painless labor in combination with the local anesthetic ropivacaine. One aim of the current study was to investigate the effects of sufentanil and ropivacaine on umbilical cord mesenchymal stem cells (UCMSCs). A second aim of this study was to determine whether sufentanil attenuated the cytotoxicity of ropivacaine in vitro. UCMSCs were divided into 3 groups: one was treated with ropivacaine at a concentration of 50, 100, 200, or 400 μg/mL, another was treated with sufentanil at a concentration of 0.5, 5, 50, or 500 nmol/L, and a third was treated with a combination of ropivacaine at a concentration of 200 μg/mL and sufentanil at a concentration of 0.5, 5, 50, or 500 nmol/L. Results indicated that cell proliferation decreased in cells treated with ropivacaine while it increased in cells treated with sufentanil. In addition, sufentanil limited the inhibitory effect of ropivacaine on UCMSC growth in a dose- and time-dependent manner. Combined treatment with ropivacaine at a concentration of 200 μg/mL and sufentanil at a concentration of 500 nmol/L decreased the proportion of dead and apoptotic UCMSCs, and fewer cells were arrested in the S phase compared to cells treated with ropivacaine. Sufentanil inhibited the apoptosis induced by ropivacaine by increasing miR-182-5p, which regulated the expression of mRNA of the pro-apoptotic genes B-cell lymphoma/leukemia 10 (BCL10) and cytochrome c, somatic (CYCS). Sufentanil also increased the expression of mRNA of anti-apoptotic genes. In short, ropivacaine inhibits the cell viability and induces the apoptosis of UCMSCs in vitro while sufentanil attenuates this apoptosis by regulating miR182-5p/BCL10/CYCS.

Myocyte membrane and microdomain modifications in diabetes: determinants of ischemic tolerance and cardioprotection

Cardiovascular disease, predominantly ischemic heart disease (IHD), is the leading cause of death in diabetes mellitus (DM). In addition to eliciting cardiomyopathy, DM induces a ‘wicked triumvirate’: (i) increasing the risk and incidence of IHD and myocardial ischemia; (ii) decreasing myocardial tolerance to ischemia–reperfusion (I–R) injury; and (iii) inhibiting or eliminating responses to cardioprotective stimuli. Changes in ischemic tolerance and cardioprotective signaling may contribute to substantially higher mortality and morbidity following ischemic insult in DM patients. Among the diverse mechanisms implicated in diabetic impairment of ischemic tolerance and cardioprotection, changes in sarcolemmal makeup may play an overarching role and are considered in detail in the current review. Observations predominantly in animal models reveal DM-dependent changes in membrane lipid composition (cholesterol and triglyceride accumulation, fatty acid saturation vs. reduced desaturation, phospholipid remodeling) that contribute to modulation of caveolar domains, gap junctions and T-tubules. These modifications influence sarcolemmal biophysical properties, receptor and phospholipid signaling, ion channel and transporter functions, contributing to contractile and electrophysiological dysfunction, cardiomyopathy, ischemic intolerance and suppression of protective signaling. A better understanding of these sarcolemmal abnormalities in types I and II DM (T1DM, T2DM) can inform approaches to limiting cardiomyopathy, associated IHD and their consequences. Key knowledge gaps include details of sarcolemmal changes in models of T2DM, temporal patterns of lipid, microdomain and T-tubule changes during disease development, and the precise impacts of these diverse sarcolemmal modifications. Importantly, exercise, dietary, pharmacological and gene approaches have potential for improving sarcolemmal makeup, and thus myocyte function and stress-resistance in this ubiquitous metabolic disorder.

Sarcolemmal dependence of cardiac protection and stress-resistance: roles in aged or diseased hearts

Disruption of the sarcolemmal membrane is a defining feature of oncotic death in cardiac ischaemia-reperfusion (I-R), and its molecular makeup not only fundamentally governs this process but also affects multiple determinants of both myocardial I-R injury and responsiveness to cardioprotective stimuli. Beyond the influences of membrane lipids on the cytoprotective (and death) receptors intimately embedded within this bilayer, myocardial ionic homeostasis, substrate metabolism, intercellular communication and electrical conduction are all sensitive to sarcolemmal makeup, and critical to outcomes from I-R. As will be outlined in this review, these crucial sarcolemmal dependencies may underlie not only the negative effects of age and common co-morbidities on myocardial ischaemic tolerance but also the on-going challenge of implementing efficacious cardioprotection in patients suffering accidental or surgically induced I-R. We review evidence for the involvement of sarcolemmal makeup changes in the impairment of stress-resistance and cardioprotection observed with ageing and highly prevalent co-morbid conditions including diabetes and hypercholesterolaemia. A greater understanding of membrane changes with age/disease, and the inter-dependences of ischaemic tolerance and cardioprotection on sarcolemmal makeup, can facilitate the development of strategies to preserve membrane integrity and cell viability, and advance the challenging goal of implementing efficacious 'cardioprotection' in clinically relevant patient cohorts. Linked Articles This article is part of a themed section on Molecular Pharmacology of G Protein-Coupled Receptors. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v173.20/issuetoc.

Prospects for Creation of Cardioprotective and Antiarrhythmic Drugs Based on Opioid Receptor Agonists

It has now been demonstrated that the μ, δ1 , δ2 , and κ1 opioid receptor (OR) agonists represent the most promising group of opioids for the creation of drugs enhancing cardiac tolerance to the detrimental effects of ischemia/reperfusion (I/R). Opioids are able to prevent necrosis and apoptosis of cardiomyocytes during I/R and improve cardiac contractility in the reperfusion period. The OR agonists exert an infarct-reducing effect with prophylactic administration and prevent reperfusion-induced cardiomyocyte death when ischemic injury of heart has already occurred; that is, opioids can mimic preconditioning and postconditioning phenomena. Furthermore, opioids are also effective in preventing ischemia-induced arrhythmias.

Hydrosulfide attenuates acute myocardial ischemic injury through the glycogen synthase kinase-3β/β-catenin signaling pathway

The endogenous signaling gasotransmitter, hydrosulfide (H2S), has been shown to exert cardioprotective effects against acute myocardial infarction (AMI) due to ischemic injury. However, the mechanisms responsible for these effects are not yet fully understood. In this study, we investigated whether sodium hydrogen sulfide (NaHS), an H2S donor, attenuates acute myocardial ischemic injury through glycogen synthase kinase-3β (GSK-3β)/β-catenin signaling. For this purpose, we utilized an in vivo rat model of AMI by occluding the left anterior descending coronary artery. NaHS (0.39, 0.78 or 1.56 mg/kg, intraperitoneally), the GSK-3β inhibitor, SB216763 (0.6 mg/kg, intravenously), or 1% dimethylsulfoxide (2 ml/kg, intravenously) were administered to the rats. The results demonstrated that the administration of medium- and high-dose NaHS and SB216763 significantly improved rat cardiac function, as evidenced by an increase in the mean arterial pressure, left ventricular developed pressure, contraction and relaxation rates, as well as a decrease in left ventricular end-diastolic pressure. In addition, the administration of NaHS and SB216763 attenuated myocardial injury as reflected by a decrease in apoptotic cell death and in the serum lactate dehydrogenase concentrations, and prevented myocardial structural changes. The administration of NaHS and SB216763 increased the concentrations of phosphorylated (p-)GSK-3β, the p-GSK-3β/t-GSK-3β ratio and downstream protein β-catenin. Moreover, western blot and immunohistochemical analyses of apoptotic signaling pathway proteins further established the cardioprotective potential of NaHS, as reflected by the upregulation of Bcl-2 expression, the downregulation of Bax expression, and a decrease in the number of TUNEL-positive stained cells. These findings suggest that hydrosulfide exerts cardioprotective effects against AMI-induced apoptosis through the GSK-3β/β-catenin signaling pathway.

Long-term insulin treatment restores cardioprotection induced by sufentanil postconditioning in diabetic rat heart

Sufentanil, a commonly used opioid analgesic, could mimic ischemia postconditioning to attenuate ischemia reperfusion injury, but this effect might be hindered in diabetic animals by inhibition of glycogen synthase kinase-3β phosphorylation. Also, diabetes can abrogate the cardioprotection of sevoflurane (an inhaled anesthetic) against ischemia reperfusion injury, and short-term insulin treatment does not restore protection by sevoflurane postconditioning. We hypothesized that long-term insulin treatment might restore the cardioprotective effect of sufentanil postconditioning in diabetic rats via phosphorylation of glycogen synthase kinase-3β. Streptozotocin (55 mg/kg)-induced diabetic rats received insulin (Novolin N, 6-8 u/d) for two days or two weeks, then were exposed to 30-min ischemia and 120-min reperfusion. Sufentanil postconditioning was performed 5 min before the onset of reperfusion. Controls included non-diabetic rats, sham surgery for ischemia/reperfusion, and sufentanil vehicle. Infarct size, cardiac troponin I, and phosphorylated glycogen synthase kinase-3β were examined. Sufentanil postconditioning reduced infarct size by 46% in non-diabetic rats (P < 0.001), but diabetes prevented this protective effect. Two-day insulin treatment was not effective, but two-week treatment reduced infarct size by 45% (P < 0.001), reduced cardiac troponin I by 33% (P < 0.001), and increased phosphorylated glycogen synthase kinase-3β levels (P < 0.001) in the diabetic sufentanil postconditioning group. In conclusion, sufentanil-induced cardioprotection was restored by long-term insulin treatment. The underlying mechanism may be increased phosphorylation of glycogen synthase kinase-3β.

Opioid receptors and cardioprotection - 'opioidergic conditioning' of the heart

Ischaemic heart disease (IHD) remains a major cause of morbidity/mortality globally, firmly established in Westernized or 'developed' countries and rising in prevalence in developing nations. Thus, cardioprotective therapies to limit myocardial damage with associated ischaemia-reperfusion (I-R), during infarction or surgical ischaemia, is a very important, although still elusive, clinical goal. The opioid receptor system, encompassing the δ (vas deferens), κ (ketocyclazocine) and μ (morphine) opioid receptors and their endogenous opioid ligands (endorphins, dynorphins, enkephalins), appears as a logical candidate for such exploitation. This regulatory system may orchestrate organism and organ responses to stress, induces mammalian hibernation and associated metabolic protection, triggers powerful adaptive stress resistance in response to ischaemia/hypoxia (preconditioning), and mediates cardiac benefit stemming from physical activity. In addition to direct myocardial actions, central opioid receptor signalling may also enhance the ability of the heart to withstand I-R injury. The δ- and κ-opioid receptors are strongly implicated in cardioprotection across models and species (including anti-infarct and anti-arrhythmic actions), with mixed evidence for μ opioid receptor-dependent protection in animal and human tissues. A small number of clinical trials have provided evidence of cardiac benefit from morphine or remifentanil in cardiopulmonary bypass or coronary angioplasty patients, although further trials of subtype-specific opioid receptor agonists are needed. The precise roles and utility of this GPCR family in healthy and diseased human myocardium, and in mediating central and peripheral survival responses, warrant further investigation, as do the putative negative influences of ageing, IHD co-morbidities, and relevant drugs on opioid receptor signalling and protective responses.