Background

It has been reported that cannabinoid receptors 2 (CB2 receptors) play an important role in the pathophysiological process of sepsis, which may also be associated with the regulation of pyroptosis, an inflammatory programmed cell death. The present study aimed to investigate the protective effect of CB2 receptors on myocardial damage in a model of septic mice by inhibiting pyroptosis.

Methods

The C57BL/6 mice underwent cecal ligation and puncture (CLP) to induce sepsis. All mice were randomly divided into the sham, CLP, or CLP+HU308 group. Blood and heart tissue samples were collected 12 h after surgery. Hematoxylin and eosin staining was used for analyzing histopathological results. Creatine kinase isoenzymes (CK-MB) and IL-1β were measured using ELISA, while lactate dehydrogenase (LDH) level was determined using photoelectric colorimetry. The expression levels of CB2 receptors and pyroptosis-associated proteins (NLRP3, caspase-1, and GSDMD) were measured using western blotting. The location and distribution of CB2 receptors and caspase-1 in myocardial tissues were assessed by immunofluorescence. TUNEL staining was used to quantify the number of dead cells in myocardial tissues.

Results

The CLP procedure increased CB2 receptor expression in mice. CB2 receptors were located in myocardial macrophages. Activating CB2 receptors decreased the levels of myocardial damage mediator LDH, CK-MB, and inflammatory cytokine IL-1β. The results also showed that CLP increased the pyroptosis in myocardial tissues, while CB2 agonist HU308 inhibited pyroptosis by decreasing the level of NLRP3 and activating caspase-1 and GSDMD.

Conclusions

CB2 receptor activation has a protective effect on the myocardium of mice with sepsis by inhibiting pyroptosis.

中文翻译：

---

大麻素受体 2 的激活通过抑制细胞焦亡减轻盲肠结扎和穿刺引起的脓毒症中的心肌损伤

背景

据报道，大麻素受体2（CB2受体）在脓毒症的病理生理过程中发挥重要作用，也可能与焦亡（一种炎症性程序性细胞死亡）的调节有关。本研究旨在探讨CB2受体通过抑制细胞焦亡对脓毒症小鼠模型心肌损伤的保护作用。

方法

C57BL/6 小鼠接受盲肠结扎穿刺 (CLP) 以诱导败血症。所有小鼠被随机分为假手术组、CLP组或CLP+HU308组。手术后12小时采集血液和心脏组织样本。使用苏木精和伊红染色来分析组织病理学结果。使用 ELISA 测定肌酸激酶同工酶 (CK-MB) 和 IL-1β，使用光电比色法测定乳酸脱氢酶 (LDH) 水平。使用蛋白质印迹法测量 CB2 受体和焦亡相关蛋白（NLRP3、caspase-1 和 GSDMD）的表达水平。通过免疫荧光评估心肌组织中CB2受体和caspase-1的位置和分布。TUNEL染色用于量化心肌组织中死亡细胞的数量。

结果

CLP 程序增加了小鼠中 CB2 受体的表达。CB2受体位于心肌巨噬细胞中。激活 CB2 受体可降低心肌损伤介质 LDH、CK-MB 和炎症细胞因子 IL-1β 的水平。结果还表明，CLP增加了心肌组织的焦亡，而CB2激动剂HU308通过降低NLRP3的水平并激活caspase-1和GSDMD来抑制焦亡。

结论

CB2受体激活通过抑制细胞焦亡对脓毒症小鼠心肌具有保护作用。