GSDMD KNOCKOUT ALLEVIATES SEPSIS-ASSOCIATED SKELETAL MUSCLE ATROPHY BY INHIBITING IL18/AMPK SIGNALING.

Abstract: 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.