Lobetyolin reinforces endothelial cytoskeletal integrity to alleviate Pseudomonas aeruginosa-induced acute lung injury via targeting ACTN1

Ethnopharmacological relevance: Codonopsis Radix (CR), known as Dangshen in traditional Chinese medicine,is frequently used to tonify Qi and strengthen the spleen and lung. Clinically, "Lung-Qi deficiency" manifests as respiratory weakness and susceptibility to Infection. The traditional action of "consolidating Qi to protect the exterior" parallels the physiological preservation of the pulmonary endothelial barrier. However, the bioactive basis linking this traditional efficacy to barrier reinforcement remains unclear.

Aim of the study: This study evaluates the protective effects of CR against Pseudomonas aeruginosa-induced acute lung injury (ALI), identifies the primary bioactive component responsible for barrier protection, and elucidates its molecular mechanism involving cytoskeletal stabilization.

Materials and methods: A P. aeruginosa-induced ALI mouse model was established to assess the efficacy of CR extract (CRE) and its polyacetylene glycoside, lobetyolin (LBT). Lung injury severity, inflammatory responses, and endothelial barrier function were systematically evaluated. Bioactivity-guided fractionation screened for active constituents. The mechanism was investigated using integrated transcriptomics, chemical proteomics, and molecular docking, validated by in vitro and in vivo experiments.

Results: Both CRE and LBT significantly attenuated lung histopathology, diminished pulmonary edema, and suppressed leukocyte infiltration and pro-inflammatory cytokine production. LBT was identified as the key bioactive constituent restoring endothelial barrier integrity, evidenced by upregulated expression and junctional localization of VE-Cadherin, ZO-1, and Claudin-5. Mechanistically, LBT directly targets α-actinin-1 (ACTN1). Functioning as a "molecular stabilizer", LBT enhances ACTN1-F-actin affinity, promoting cortical actin organization and stabilizing intercellular junctions under inflammatory stress.

Conclusions: This study identifies LBT as a novel structural consolidator of the vascular endothelial barrier. By demonstrating that LBT reinforces endothelial cytoskeletal organization via ACTN1, our findings offer a compelling modern scientific interpretation of the traditional efficacy of CR in "tonifying Lung-Qi": physically strengthening the biological barrier. Furthermore, targeting ACTN1-mediated Cytoskeleton modulation presents a promising strategy for treating ALI and vascular leakage disorders.