CLU attenuates sepsis-associated acute lung injury by inhibiting Bax-mediated mitochondrial damage

Sepsis-induced acute lung injury (ALI) is typified by unchecked inflammation and widespread cell death, yet the underlying molecular pathways are still unclear.

Differentially expressed genes were identified from the GSE10474 dataset. Protein-protein interaction (PPI) network analysis was employed to identify hub genes, and expression validation was carried out. An in vitro model of ALI caused by sepsis was applied to confirm CLU expression. CLU expression was assessed by qRT-PCR and Western blotting. To investigate the function and mechanism of CLU expression, functional assays such as cell viability assays, flow cytometry, co-immunoprecipitation (Co-IP), transmission electron microscopy (TEM), cytochrome c (Cyto c) release, and Reactive Oxygen Species (ROS) assays, ATP content, and mitochondrial membrane potential (ΔΨm) were carried out.

Bioinformatics analysis identified six hub genes (CDKN1A, HIST1H3F, HLA-DQB1, CD74, VDAC1, and CLU) as downregulated in sepsis-induced ALI. The reduction of CLU expression in the ALI model was validated by experimental validation, whereas its overexpression decreased apoptosis and restored cell viability. Mechanistically, CLU interacted with Bax and inhibited its translocation to mitochondria, which may contribute to Cyto c release, preserving ATP content and ΔΨm, maintaining mitochondrial morphology, and reducing ROS accumulation. Crucially, the protective effect of CLU was attenuated by overexpressing Bax, which resulted in increased apoptosis, lower cell viability, increased reactive oxygen species, and worsened mitochondrial damage.

Our in‑vitro findings suggest that CLU could mitigate apoptosis in the sepsis‑induced ALI cell model, at least partly through modulating Bax‑dependent mitochondrial damage. These results point to CLU as a possible treatment target for ALI caused by sepsis.