Department of Anesthesiology, First Affiliated Hospital of Kunming Medical University, Kunming, Yunnan, China.
Department of Cardiac Surgery, First Affiliated Hospital of Kunming Medical University, Kunming, Yunnan, China.
Biomed Pharmacother. 2023 Sep;165:115255. doi: 10.1016/j.biopha.2023.115255. Epub 2023 Aug 5.
The current study intended to delve into the mechanisms of dexmedetomidine (Dex) in regulating myocardial pyroptosis against myocardial ischemia/reperfusion injury (MIRI). The rat MIRI models were induced by ligation/release of the coronary artery in vivo and Langendorff perfusion ex vivo. Hemodynamic parameters, infarction sizes, and histopathological changes were assessed to understand the effects of Dex on MIRI. We explored the mechanisms through functional experiments on an H9c2 cell hypoxia/reoxygenation (H/R) model. Cell viability and apoptosis were evaluated using cell counting kit 8 (CCK-8) and AV/PI dual staining respectively. The expressions of miR-665 and MEF2D mRNA were detected by qRT-PCR. Western blot was employed to determine the expression levels of pyroptosis- and signaling pathway- related proteins. The interplays between miR-665 and MEF2D were validated by Dual-luciferase reporter assays. Our findings indicated that Dex preconditioning dramatically attenuated hemodynamic derangements, infarct size, and histopathological damage in rats undergoing MIRI. Dex markedly augmented cell viability, while suppressing cell apoptosis and expressions of NLRP3, cleaved-caspase-1, ASC, GSDMD, IL-1β, and IL-18 in H9c2 cells subjected to H/R injury. MiR-665 was significantly upregulated, MEF2D and Nrf2 downregulated following H/R, whereas Dex preconditioning reversed these changes. MEF2D was validated to be a target gene of miR-665. Overexpression of miR-665 decreased the expression of MEF2D and blunted the protective effects of Dex in H9c2 cells. Moreover, the functional rescue experiment further verified that Dex regulated MEF2D/Nrf2 pathway via miR-665. In conclusion, Dex mitigates MIRI through inhibiting pyroptosis via regulating miR-665/MEF2D/Nrf2 axis.
本研究旨在探讨右美托咪定（Dex）在调节心肌缺血/再灌注损伤（MIRI）中心肌细胞焦亡中的作用机制。体内结扎/释放冠状动脉和体外 Langendorff 灌流建立大鼠 MIRI 模型。通过血流动力学参数、梗死面积和组织病理学变化评估 Dex 对 MIRI 的影响。我们通过 H9c2 细胞缺氧/复氧（H/R）模型进行功能实验来探讨机制。通过细胞计数试剂盒 8（CCK-8）和 AV/PI 双重染色分别评估细胞活力和细胞凋亡。通过 qRT-PCR 检测 miR-665 和 MEF2D mRNA 的表达。通过 Western blot 测定焦亡和信号通路相关蛋白的表达水平。通过双荧光素酶报告实验验证 miR-665 和 MEF2D 之间的相互作用。结果表明，Dex 预处理可显著减轻大鼠 MIRI 时的血流动力学紊乱、梗死面积和组织病理学损伤。Dex 明显增加细胞活力，同时抑制 H/R 损伤的 H9c2 细胞凋亡和 NLRP3、cleaved-caspase-1、ASC、GSDMD、IL-1β和 IL-18 的表达。H/R 后 miR-665 显著上调，MEF2D 和 Nrf2 下调，而 Dex 预处理可逆转这些变化。MEF2D 被验证为 miR-665 的靶基因。miR-665 的过表达降低了 MEF2D 的表达，并削弱了 Dex 在 H9c2 细胞中的保护作用。此外，功能拯救实验进一步证实，Dex 通过 miR-665 调节 MEF2D/Nrf2 通路。综上所述，Dex 通过调节 miR-665/MEF2D/Nrf2 轴抑制焦亡减轻 MIRI。
