Acute lung injury (ALI) is a major complication of sepsis. Sepsis-induced ALI (S-ALI) is closely related to excessive mitochondrial fission induced by the fission protein dynamin-related protein 1 (Drp1), and this process may be modulated in part through the calcineurin (CaN)/Drp1 signaling pathway. This work aimed to assess the protective impact of Mdivi-1, a Drp1 inhibitor, on ALI caused by sepsis and to clarify the associated molecular mechanisms. In vivo experiments employed the cecal ligation and puncture (CLP) method to induce sepsis-associated ALI in mice. In vitro, an MLE-12 mouse alveolar epithelial cell model was induced by lipopolysaccharide (LPS). Lung injury and inflammation were evaluated through histological staining, lung wet-to-dry ratio, and measurement of inflammatory cytokines; Western blot was used to assess proteins related to mitochondrial dynamics, the CaN/Drp1 signaling pathway, and apoptosis; cell apoptosis was analyzed using fluorescence-based assays, and reactive oxygen species (ROS) accumulation as well as mitochondrial membrane potential (ΔΨm) changes were measured. CLP-induced mice and LPS-treated MLE-12 cells exhibited significant lung injury, elevated inflammatory cytokines, decreased mitochondrial fusion proteins, increased fission proteins, elevated ROS levels, reduced ΔΨm, decreased ATP production, and increased apoptosis. Mdivi-1 treatment markedly alleviated CLP/LPS-induced lung injury and inflammation, restored the expression of Occludin and zonula occludens-1 (ZO-1), improved abnormal mitochondrial dynamics, reduced ROS levels, restored ΔΨm and adenosine triphosphate (ATP) content, and inhibited apoptosis. In addition, Mdivi-1 blocked dysregulated activation of the CaN/Drp1 signaling pathway. The Drp1 inhibitor Mdivi-1 alleviates S-ALI by inhibiting the CaN/Drp1 signaling pathway, improving mitochondrial dynamics imbalance, reducing oxidative stress and apoptosis, and partially restoring the alveolar epithelial barrier. The present findings imply that interventions aimed at Drp1 and mitochondrial dynamics regulation might serve as a viable therapeutic option for S-ALI.
Chen et al. (Thu,) studied this question.