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October 20, 2019
10/20/2019 9:30:00 AM - 10/20/2019 11:00:00 AM
Room W312C
Protective Mechanisms of Pharmacologic Preconditioning Against Myocardial Ischemia Reperfusion Injury: Role of BCL-2 Family Proteins
Romain Rozier, M.D., M.S., Sébastien Pommier, M.D., Marc Raucoules, M.D., Jean-Ehrland Ricci, Ph.D., Michel Carles, M.D.,Ph.D.
Archet 2 Universitary Medical Center, Nice, France
Disclosures: R. Rozier: None.S. Pommier: None.M. Raucoules: None.J. Ricci: None.M. Carles: None.
Background: Myocardial ischemia reperfusion (IR) injury is the leading cause of perioperative morbi-mortality. Protective effect of pharmacologic preconditioning such as anesthetic preconditioning (APC) with sevoflurane (SEV) has been widely demonstrated in human and animal models. APC seems to protect myocardial cells from apoptosis, a programmed type of cell death tightly controlled by Bcl-2 family proteins. However, the involved mechanisms in APC have yet to be characterized. We hypothesized that APC protects against myocardial apoptotic cell death by regulating Bcl-2 anti-apoptotic members. Methods: In order to study the SEV-induced APC mechanisms against myocardial IR, we used a validated in vitro model reproducing IR injury. Rat cardiomyoblast cells H9c2 were cultivated in 0.1% O2 hypoxia in the presence of ischemia-mimicking medium. After 90 mins of ischemia, the reperfusion injuries are induced by replacing the culture medium with a Krebs-Henseleit pre-incubated normoxic medium in ambient air for 60 mins. APC was performed by adding SEV directly into the culture medium at an initial concentration of 20 mM, prior to ischemia, for 60 mins. We then used another preconditioning agent, an anti-diabetic drug metformin (MET) 20 μM to explore the same signaling pathways. Apoptotic cell death was measured by caspase activity assay and western blotting (expression of cleaved caspase 3) under IR and APC conditions. Results: Our model faithfully reproduced the protective effect of APC which results in a significant decreased apoptosis under IR (50% reduction of the Caspase 3 enzymatic activity, correlated with a decrease of Caspase 3 cleavage). We showed that SEV induces overexpression of the anti-apoptotic protein Bcl-xL, which is responsible for the protective effect of APC. Furthermore, these observations were confirmed in vivo in mouse heart lysates. We demonstrated that Bcl-xL overexpression was due to the activation of the protein kinase Akt. Interestingly, we were able to show that preconditioning with MET reproduces the protective effect of SEV by inducing an Akt-dependent Bcl-xL overexpression. Indeed, SEV and MET, which are both complex 1 inhibitors of mitochondrial respiratory chain, seem to share a common Reactive Oxygenated Species-dependent protective mechanism responsible for Bcl-xL protein regulation. Interestingly, retrospective clinical data over a 3-year period (2016-2018), from our ICU team, showed that among 277 consecutive patients suffering a cardiac arrest, those under MET before ICU admission have a better survival rate (MET+ 41% versus MET- 22% p=0,022). Conclusion: Our results elucidates the molecular mechanisms by which SEV induces APC against IR injuries, i.e. the role of Bcl-xl (part of the Bcl2 family). Moreover, this study shows that pharmacologic preconditioning with the anti-diabetic drug MET promotes similar protective effect, sharing with SEV the same signaling pathway. Finally, preliminary clinical data suggests that pharmacological preconditioning could potentially reduce the mortality after a cardiac arrest. Altogether, our results could be of interest to improve the perioperative management of patients at risk of ischemia reperfusion events, such as patients with a high cardiovascular risk.

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