Zhang Yongsheng, Li Tonghan, Liu Yukun, Wang Chuntao, Wang Dongfang, Xu Ligang, Zhao Hong, Bai Xiangjun, Li Zhanfei, Wang Yuchang
Department of Plastic and Cosmetic Surgery, Tongji Hospital, Tongji Hospital of Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
Shock. 2024 Oct 1;62(4):565-573. doi: 10.1097/SHK.0000000000002430. Epub 2024 Sep 3.
Background: Sepsis commonly leads to skeletal muscle atrophy, characterized by substantial muscle weakness and degeneration, ultimately contributing to an adverse prognosis. Studies have shown that programmed cell death is an important factor in the progression of muscle loss in sepsis. However, the precise role and mechanism of pyroptosis in skeletal muscle atrophy are not yet fully comprehended. Therefore, we aimed to examine the role and mechanism of action of the pyroptosis effector protein GSDMD in recognized cellular and mouse models of sepsis. Methods: The levels of GSDMD and N-GSDMD in skeletal muscle were evaluated 2, 4, and 8 days after cecal ligation and puncture. Sepsis was produced in mice that lacked the Gsdmd gene (Gsdmd knockout) and in mice with the normal Gsdmd gene (wild-type) using a procedure called cecal ligation and puncture. The degree of muscular atrophy in the gastrocnemius and tibialis anterior muscles was assessed 72 h after surgery in the septic mouse model. In addition, the architecture of skeletal muscles, protein expression, and markers associated with pathways leading to muscle atrophy were examined in mice from various groups 72 h after surgery. The in vitro investigations entailed the use of siRNA to suppress Gsdmd expression in C2C12 cells, followed by stimulation of these cells with lipopolysaccharide to evaluate the impact of Gsdmd downregulation on muscle atrophy and the related signaling cascades. Results: This study has demonstrated that the GSDMD protein, known as the "executive" protein of pyroptosis, plays a crucial role in the advancement of skeletal muscle atrophy in septic mice. The expression of N-GSDMD in the skeletal muscle of septic mice was markedly higher compared with the control group. The Gsdmd knockout mice exhibited notable enhancements in survival, muscle strength, and body weight compared with the septic mice. Deletion of the Gsdmd gene reduced muscular wasting in the gastrocnemius and tibialis anterior muscles caused by sepsis. Studies conducted in living organisms ( in vivo ) and in laboratory conditions ( in vitro ) have shown that the absence of the Gsdmd gene decreases indicators of muscle loss associated with sepsis by blocking the IL18/AMPK signaling pathway. Conclusion: The results of this study demonstrate that the lack of Gsdmd has a beneficial effect on septic skeletal muscle atrophy by reducing the activation of IL18/AMPK and inhibiting the ubiquitin-proteasome system and autophagy pathways. Therefore, our research provides vital insights into the role of pyroptosis in sepsis-related skeletal muscle wasting, which could potentially lead to the development of therapeutic and interventional approaches for preventing septic skeletal muscle atrophy.
脓毒症通常会导致骨骼肌萎缩，其特征为严重的肌肉无力和退化，最终导致不良预后。研究表明，程序性细胞死亡是脓毒症中肌肉损失进展的一个重要因素。然而，细胞焦亡在骨骼肌萎缩中的确切作用和机制尚未完全阐明。因此，我们旨在研究细胞焦亡效应蛋白GSDMD在公认的脓毒症细胞和小鼠模型中的作用及作用机制。
在盲肠结扎和穿刺术后2天、4天和8天评估骨骼肌中GSDMD和N-GSDMD的水平。使用盲肠结扎和穿刺程序，在缺乏Gsdmd基因的小鼠（Gsdmd基因敲除小鼠）和具有正常Gsdmd基因的小鼠（野生型小鼠）中诱导脓毒症。在脓毒症小鼠模型中，于术后72小时评估腓肠肌和胫前肌的肌肉萎缩程度。此外，在术后72小时对各组小鼠的骨骼肌结构、蛋白质表达以及与导致肌肉萎缩的途径相关的标志物进行检测。体外研究包括使用小干扰RNA（siRNA）抑制C2C12细胞中Gsdmd的表达，随后用脂多糖刺激这些细胞，以评估Gsdmd下调对肌肉萎缩及相关信号级联反应的影响。
本研究表明，被称为细胞焦亡“执行”蛋白的GSDMD蛋白在脓毒症小鼠骨骼肌萎缩进展中起关键作用。脓毒症小鼠骨骼肌中N-GSDMD的表达明显高于对照组。与脓毒症小鼠相比，Gsdmd基因敲除小鼠在存活率、肌肉力量和体重方面有显著提高。Gsdmd基因的缺失减少了脓毒症引起的腓肠肌和胫前肌的肌肉消耗。在活体（体内）和实验室条件（体外）进行的研究表明，Gsdmd基因的缺失通过阻断IL18/AMPK信号通路降低了与脓毒症相关的肌肉损失指标。
本研究结果表明，缺乏Gsdmd通过减少IL18/AMPK的激活以及抑制泛素-蛋白酶体系统和自噬途径，对脓毒症性骨骼肌萎缩具有有益作用。因此，我们的研究为细胞焦亡在脓毒症相关骨骼肌消耗中的作用提供了重要见解，这可能会推动预防脓毒症性骨骼肌萎缩的治疗和干预方法的发展。
