Precondition of sevoflurane upregulates TIMP3 expression to alleviate myocardial ischemia/reperfusion injury

Cardioprotective Mechanisms of Interrupted Anesthetic Preconditioning with Sevoflurane in the Setting of Ischemia/Reperfusion Injury in Rats

Background: Anesthetic preconditioning (AP) is known to mimic ischemic preconditioning. The purpose of this study was to investigate the effects of an interrupted sevoflurane administration protocol on myocardial ischemia/reperfusion (I/R) injury. Methods: Male Wistar rats (n = 60) were ventilated for 30 min with room air (control group, CG) or with a mixture of air and sevoflurane (1 minimum alveolar concentration—MAC) in 5-min cycles, alternating with 5-min wash-out periods (preconditioned groups). Cytokines implicated in the AP response were measured. An (I/R) lesion was produced immediately after the sham intervention (CG) and preconditioning protocol (early AP group, EAPG) or 24 h after the intervention (late AP group, LAPG). The area of fibrosis, the degree of apoptosis and the number of c-kit+ cells was estimated for each group. Results: Cytokine levels were increased post AP. The area of fibrosis decreased in both EAPG and LAPG compared to the CG (p < 0.0001). When compared to the CG, the degree of apoptosis was reduced in both LAPG (p = 0.006) and EAPG (p = 0.007) and the number of c-kit+ cells was the greatest for the LAPG (p < 0.0001). Conclusions: Sevoflurane preconditioning, using an interrupted anesthesia protocol, is efficient in myocardial protection and could be beneficial to reduce perioperative or periprocedural ischemia in patients with increased cardiovascular risk.

Exosomal miR-17-3p Alleviates Programmed Necrosis in Cardiac Ischemia/Reperfusion Injury by Regulating TIMP3 Expression

Objective

Myocardial ischemia/reperfusion (I/R) injury can aggravate myocardial injury. Programmed necrosis plays a crucial role in this injury. However, the role of exosomal miRNAs in myocardial I/R injury remains unclear. Therefore, this study is aimed at exploring the function and mechanism of exosomal miR-17-3p in myocardial I/R injury.

Methods

The myocardial I/R injury animal model was established in C57BL/6 mice. Exosomes were identified using transmission electron microscopy (TEM), nanoparticle tracking analysis (NTA), and Western blotting. Programmed necrosis was detected by PI staining. Heart function and myocardial infarct size were evaluated using echocardiography and triphenyl tetrazolium chloride (TTC) staining, respectively. Histopathological changes were visualized by hematoxylin and eosin (H&E) and Masson staining. The regulation of TIMP3 expression by miR-17-3p was verified using a dual-luciferase reporter assay. Lactate dehydrogenase (LDH) and tumor necrosis factor-α (TNF-α) levels were measured by enzyme-linked immunosorbent assays (ELISA). TIMP3 expression was measured by quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and Western blotting.

Results

We demonstrated that miR-17-3p was significantly downregulated in peripheral blood exosomes after cardiac I/R injury. Further analysis indicated that exosomal miR-17-3p attenuated H₂O₂-induced programmed necrosis in cardiomyocytes in vitro. Moreover, TIMP3 was a target for miR-17-3p. TIMP3 affected H₂O₂-induced programmed necrosis in cardiomyocytes. This effect was modulated by miR-17-3p in vitro. Furthermore, exosomal miR-17-3p greatly alleviated cardiac I/R injury in vivo.

Conclusions

The present study demonstrated that exosomal miR-17-3p alleviated the programmed necrosis associated with cardiac I/R injury by regulating TIMP3 expression. These findings could represent a potential treatment for I/R injury.