Objective: To observe the effect of inhibiting mitochondrial oxidative stress and NLRP3 inflammasomes on high glucose (HG)-induced pyroptosis and ferroptosis in H9C2 cardiac muscle cells and explore the possible interactions between mitochondrial reactive oxygen species (ROS) and inflammasomes.
Methods: H9C2 cells exposed to high glucose (35 mmol/L) were treated with the mitochondrial antioxidant mitoquinone (MitoQ), the NLRP3 antagonist MCC950, or both MCC950 and rotenone (a mitochondrial electron transport antagonist), and the cell viability was measured with CCK-8 assay. The cellular and mitochondrial ROS levels were measured using CellRox and Mitosox fluorescent probes, respectively. The cellular NLRP3 inflammasome level was detected with immunofluorescence assay, and the expressions of the key proteins related with pyroptosis and ferroptosis were determined with Western blotting.
Results: HG exposure significantly lowered the viability of H9C2 cells (P < 0.01), reduced the expression of GPX4 protein (a key protein related with ferroptosis) (P < 0.01), and increased the fluorescence intensities of NLRP3 (P < 0.01) and ROS (at both the cellular and mitochondrial levels, P < 0.01) and the protein expressions of NLRP3 and GSDMD-NT (P < 0.01). Treatment with either MitoQ or MCC950 significantly increased the viability of HG-exposed cells (P < 0.01), increased GPX4 expression (P < 0.01), and reduced the fluorescence intensities of NLRP3 (P < 0.01) and cellular and mitochondrial ROS (P < 0.01) and the protein expressions of NLRP3 and GSDMD-NT (P < 0.05). Compared with MCC950 treatment, treatment with both MCC950 and rotenone significantly reduced the viability of HG-exposed cells (P < 0.01), lowered GPX4 expression (P < 0.01), and increased the fluorescence intensities of ROS and NLRP3 (P < 0.01) and the protein levels of NLRP3 and GSDMD-NT (P < 0.05).
Conclusion: MitoQ inhibits mitochondrial ROS production to reduce HGinduced NLRP3 inflammasome activation and thus suppress pyroptosis and ferroptosis of cardiac muscle cells. There may be an interaction between mitochondrial ROS and NLRP3 inflammasomes.
目的: 探讨抑制线粒体氧化应激和炎症小体减轻高糖诱导的H9C2心肌细胞焦亡和铁死亡的作用，分析线粒体活性氧自由基（ROS）和炎症小体之间可能的上下游关系。
方法: 将H9C2心肌细胞按照随机数字表法随机分为5组。正常对照组（CON）：含25 mmol/L浓度葡萄糖的DMEM完全培养基；高糖损伤组（HG）：含35 mmol/L浓度的高糖完全培养基；高糖+线粒体抗氧化剂Mitoquinone（MitoQ）组（HG+MitoQ）：35 mmol/L高糖完全培养基中加入终浓度为0.5 μmol/mL的MitoQ；高糖+ NLRP3抑制剂MCC950组（HG+MCC950）：35 mmol/L高糖完全培养基中加入终浓度为1 μmol/mL的MCC950；高糖组+MCC950+线粒体电子传递抑制剂Rotenone（ROT）组（HG+MCC950+ROT）：35 mmol/L高糖完全培养基中加入终浓度为1 μmol/mL的MCC950和0.5 μmol/mL的ROT。各组心肌细胞干预24 h后，CCK-8法测定细胞活性；CellRox和MitoSox荧光探针分别测定心肌细胞内和线粒体氧化应激水平变化；免疫荧光法检测细胞内NLRP3炎症小体水平；Western blot检测心肌细胞中NLRP3、GSDMD和CleavedGSDMD（GSDMD-NT）等焦亡相关重要因子的蛋白表达和铁死亡相关因子GPX4蛋白表达。
结果: 与CON组相比，HG组细胞活性明显下降（P < 0.01），心肌细胞和线粒体内ROS荧光强度（P < 0.01）、NLRP3免疫荧光强度（P < 0.01）以及焦亡相关因子NLRP3，GSDMD和GSDMD-NT的蛋白表达（P < 0.01）均明显升高，铁死亡相关因子GPX4蛋白表达下降（P < 0.01）。与HG组相比，HG+ MitoQ和HG+MCC950组细胞活性明显升高（P < 0.01），细胞和线粒体内ROS荧光强度（P < 0.01）、NLRP3免疫荧光强度（P < 0.01）以及NLRP3、GSDMD和GSDMD-NT的蛋白表达明显降低（P < 0.05），GPX4蛋白表达增高（P < 0.01）。与HG组相比，HG+ MCC950+ROT组细胞活性和NLRP3、GSDMD-NT的蛋白表达无明显差异（P>0.05）；但与HG+MCC950组相比，HG+MCC950+ ROT组细胞活性明显降低（P < 0.01），ROS荧光强度、NLRP3炎症小体免疫荧光以及NLRP3、GSDMD-NT的蛋白表达均明显升高，GPX4蛋白表达降低（P < 0.05）。
结论: MitoQ直接抑制线粒体ROS的产生减轻了高糖诱导的心肌细胞NLRP3炎症小体的生成，减少焦亡和铁死亡的发生；抑制NLRP3炎症小体减少线粒体ROS的产生；线粒体ROS和NLRP3之间可能存在着相互影响。
Keywords: NLRP3 inflammasome; ferroptosis; high glucose; mitochondrial reactive oxygen species; pyroptosis.