The Role of Cyclooxygenase-1 and -2 in Sevoflurane-Induced Postconditioning Against Myocardial Infarction

The Protective Effect of Sevoflurane Conditionings Against Myocardial Ischemia/Reperfusion Injury: A Systematic Review and Meta-Analysis of Preclinical Trials in in-vivo Models

Objective

Myocardial ischemia/reperfusion injury (IRI) is a common and serious complication in clinical practice. Sevoflurane conditionings have been identified to provide a protection against myocardial IRI in animal experiments, but their true clinical benefits remain controversial. Here, we aimed to analyze the preclinical evidences obtained in animal models of myocardial IRI and explore the possible reasons for controversial clinical benefits.

Methods

Our primary outcome was the difference in mean infarct size between the sevoflurane and control groups in animal models of myocardial IRI. After searching the databases of PubMed, Embase, Web of Science, and the Cochrane Library, a systematic review retrieved 37 eligible studies, from which 28 studies controlled comparisons of sevoflurane preconditioning (SPreC) and 40 studies controlled comparisons of sevoflurane postconditioning (SPostC) that were made in a pooled random-effects meta-analysis. In total, this analysis included data from 313 control animals and 536 animals subject to sevoflurane conditionings.

Results

Pooled estimates for primary outcome demonstrated that sevoflurane could significantly reduce the infarct size after myocardial IRI whether preconditioning [weighted mean difference (WMD): −18.56, 95% CI: −23.27 to −13.85, P < 0.01; I² = 94.1%, P < 0.01] or postconditioning (WMD: −18.35, 95% CI: −20.88 to −15.83, P < 0.01; I² = 90.5%, P < 0.01) was performed. Interestingly, there was significant heterogeneity in effect size that could not be explained by any of the prespecified variables by meta-regression and stratified analysis. However, sensitivity analysis still identified the cardioprotective benefits of sevoflurane conditionings with robust results.

Conclusion

Sevoflurane conditionings can significantly reduce infarct size in in-vivo models of myocardial IRI. Given the fact that there is a lack of consistency in the quality and design of included studies, more well-performed in-vivo studies with the detailed characterization of sevoflurane protocols, especially studies in larger animals regarding cardioprotection effects of sevoflurane, are still required.

Effects of atorvastatin on sevoflurane postconditioning in in vivo rabbit hearts

OBJECTIVES

Myocardial ischemia-reperfusion injury is a phenomenon that promotes myocardial damage when the blood supply returns to the tissue after a period of ischemia. Anesthetic postconditioning involves myocardial protection against myocardial I/R injury. The effects of atorvastatin (ATV) on sevoflurane postconditioning against myocardial ischemia-reperfusion injury have not been thoroughly studied. The present study aimed to investigate if ATV interacts synergistically with sevoflurane postconditioning against myocardial infarction in rabbit hearts in vivo.

METHODS

Twenty-eight male rabbits underwent 30 min of left anterior descending coronary artery occlusion that was followed by reperfusion for 180 min under ketamine/xylazine (K/X) anesthesia. Rabbits were randomly assigned to four groups that included Group K/X (under K/X anesthesia only), Group POST (sevoflurane exposure at initial reperfusion), Group ATV (ATV 5 mg/kg/day administered before ischemia), and Group ATV + POST (POST intervention with atorvastatin administered once daily for 3 days). At the end of reperfusion, the myocardial infarct size and the area at risk were both measured.

RESULTS

The mean infarct sizes in the POST, ATV, and ATV + POST groups were significantly smaller compared to those in the K/X group. Furthermore, the mean infarct size in Group ATV + POST was significantly smaller than was that in Group POST and significantly smaller compared to that in Group ATV.

CONCLUSION

The combination of sevoflurane postconditioning and pre-administration of ATV further reduced the myocardial infarction size compared to that observed with sevoflurane postconditioning alone or ATV alone. Our data suggest that sevoflurane postconditioning and ATV may function additively to enhance cardioprotection.

Cyclooxygenase inhibition prior to ventricular fibrillation induced ischemia reperfusion injury impairs survival and outcomes

Nonsteroidal anti-inflammatory medications (NSAIDs) are one of the most commonly used analgesics in the world. NSAIDs decrease prostaglandin synthesis through cyclooxygenase inhibition (COX-1 or COX-2). The effects of NSAIDs on survival and outcomes from global ischemia reperfusion events and specifically from cardiac arrest (CA) remain controversial. We hypothesized that NSAIDs prior to global whole-body ischemia reperfusion (I/R) injury impairs survival and outcomes. We explored this hypothesis in our swine model of Cardiac Arrest (CA) which involves global I/R with pretreatment using a predominantly COX-1 inhibitor (Indomethacin [COX-1/min COX-2 Inh], a COX-2 Inhibitor [COX-2-Inh, (Celecoxib)] or placebo control. We determined the effects of each inhibitor on a) survival, b) myocardial injury biomarker (Troponin 1), and c) Autonomic Nervous System (ANS) injury marker (heart rate variability [HRV]) up to 3 h after resuscitation. There were no survivals in COX-1/min COX-2-Inh pretreated animals and, 87% survived in both COX-2 Inhibited and control animals. COX-2 Inh pretreated animals had an 1800 fold increase of Troponin 1 compared to baseline whereas control animals had a 90 fold increase (p < 0.001). These results along with literature review of focal I/R in animal models with COX-2 overexpression, human studies of CA, and post myocardial infarction treatment with NSAIDs, support the hypothesis that NSAIDs prior to an I/R event impairs survival and outcomes. Specifically, predominantly COX-1 inhibition impairs survival, and COX-2 inhibition induces myocardial damage, autonomic nervous system dysfunction, and increases the risk for all-cause mortality and morbidity in humans post-MI which has significant implications for the nearly 10% of the population who are taking NSAIDs.

Sevoflurane preconditioning ameliorates traumatic spinal cord injury through caveolin-3-dependent cyclooxygenase-2 inhibition

Acute traumatic spinal cord injury (tSCI) results in a lifetime of paralysis associated with a host of medical complications. The developing secondary complications of tSCI may result in further chronic neurodegenerative diseases. Sevoflurane preconditioning (SF-PreCon) has shown guaranteed protective effects in myocardial or cerebral ischemic/reperfusion injury. However, the role of SF-PreCon in tSCI still remains to be elucidated. Here, we found that SF-PreCon ameliorated the developing secondary complications through reducing the apoptosis rate and the secretion of inflammatory cytokines in injured spinal cord tissues, and therefore enhancing the recovery after tSCI. Notably, we demonstrated that SF-PreCon ameliorates tSCI through inhibiting Cycloxygenase-2 (COX-2). Importantly, we verified that SF-PreCon inhibits the expression of COX-2 and reduces the apoptosis rate after tSCI via the induction of Caveolin-3 (Cav-3). Taken together, our results suggest that SF-PreCon ameliorates tSCI via Cav-3-dependent COX-2 inhibition and provide an economical and practical method against the secondary injury after tSCI.

A combination of dietary N-3 fatty acids and a cyclooxygenase-1 inhibitor attenuates nonalcoholic fatty liver disease in mice

We sought to determine whether a combination of purified n-3 fatty acids (n-3) and SC-560 (SC), a cyclooxygenase-1-specific inhibitor, is effective in ameliorating nonalcoholic fatty liver disease in obesity. Female wild-type mice were fed a high-fat and high-cholesterol diet (HF) supplemented with n-3 in the presence or absence of SC. Mice treated with SC alone exhibited no change in liver lipids, whereas n-3-fed mice tended to have lower hepatic lipids. Mice given n-3+SC had significantly lower liver lipids compared with HF controls indicating enhanced lipid clearance. Total and sulfated bile acids were significantly higher only in n-3+SC-treated mice compared with chow diet (CD) controls. Regarding mechanisms, the level of pregnane X receptor (PXR), a nuclear receptor regulating drug/bile detoxification, was significantly higher in mice given n-3 or n-3+SC. Studies in precision-cut liver slices and in cultured hepatoma cells showed that n-3+SC enhanced not only the expression/activation of PXR and its target genes but also the expression of farnesoid X receptor (FXR), another regulator of bile synthesis/clearance, indicating that n-3+SC can induce both PXR and FXR. The mRNA level of FGFR4 which inhibits bile formation showed a significant reduction in Huh 7 cells upon n-3 and n-3+SC treatment. PXR overexpression in hepatoma cells confirmed that n-3 or SC each induced the expression of PXR target genes and in combination had an enhanced effect. Our findings suggest that combining SC with n-3 potentiates its lipid-lowering effect, in part, by enhanced PXR and/or altered FXR/FGFR4 signaling.

The mechanisms of cardio-protective effects of desflurane and sevoflurane at the time of reperfusion: anaesthetic post-conditioning potentially translatable to humans?

Myocardial conditioning is actually an essential strategy in the management of ischaemia-reperfusion injury. The concept of anaesthetic post-conditioning is intriguing, its action occurring at a pivotal moment (that of reperfusion when ischaemia reperfusion lesions are initiated) where the activation of these cardio-protective mechanisms could overpower the mechanisms leading to ischaemia reperfusion injuries. Desflurane and sevoflurane are volatile anaesthetics frequently used during cardiac surgery. This review focuses on the efficacy of desflurane and sevoflurane administered during early reperfusion as a potential cardio-protective strategy. In the context of experimental studies in animal models and in human atrial tissues in vitro, the mechanisms underlying the cardio-protective effect of these agents and their capacity to induce post-conditioning have been reviewed in detail, underlining the role of reactive oxygen species generation, the activation of the cellular signalling pathways, and the actions on mitochondria along with the translatable actions in humans; this might well be sufficient to set the basis for launching randomized clinical studies, actually needed to confirm this strategy as one of real impact.

Sevoflurane postconditioning protects rat hearts against ischemia-reperfusion injury via the activation of PI3K/AKT/mTOR signaling

Phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT) pathway plays a key role in myocardial ischemia-reperfusion (I/R) injury. Mammalian target of rapamycin (mTOR), a downstream target of PI3K/AKT signaling, is necessary and sufficient to protect the heart from I/R injury. Inhaled anesthetic sevoflurane is widely used in cardiac surgeries because its induction and recovery are faster and smoother than other inhaled anesthetics. Sevoflurane proved capable of inducing postconditioning effects in the myocardium. However, the underlying molecular mechanisms for sevoflurane-induced postconditioning (SPC) were largely unclear. In the present study, we demonstrated that SPC protects myocardium from I/R injury with narrowed cardiac infarct focus, increased ATP content, and decreased cardiomyocyte apoptosis, which are mainly due to the activation of PI3K/AKT/mTOR signaling and the protection of mitochondrial energy metabolism. Application of dactolisib (BEZ235), a PI3K/mTOR dual inhibitor, abolishes the up-regulation of pho-AKT, pho-GSK, pho-mTOR, and pho-p70s6k induced by SPC, hence abrogating the anti-apoptotic effect of sevoflurane and reducing SPC-mediated protection of heart from I/R injury. As such, this study proved that PI3K/AKT/mTOR pathway plays an important role in SPC induced cardiac protection against I/R injury.