Toosendanin alleviates acute lung injury by reducing pulmonary vascular barrier dysfunction mediated by endoplasmic reticulum stress through mTOR

Abstract

Background

Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) are severe clinical conditions with limited treatment options. Toosendanin (TSN), a triterpenoid compound with anti-inflammatory effects, has unclear efficacy in ALI.

Purpose

This study aimed to evaluate TSN's protective effects on ALI and the related mechanisms.

Methods

Lipopolysaccharide (LPS)-induced ALI models were developed in vivo and in vitro. Endothelial permeability was measured using Evans Blue dye; lipid reactive oxygen species (ROS) and apoptosis were assessed using flow cytometry. Malondialdehyde (MDA) and superoxide dismutase (SOD) levels were determined, and cell viability was measured. mRNA and protein expression were quantified using qRT-PCR and Western blotting. Network pharmacology and surface plasmon resonance were used to identify and validate TSN's targets.

Results

TSN reduced endothelial permeability and LPS-induced ALI. It lowered ROS levels, lipid peroxidation, endoplasmic reticulum (ER) stress, and apoptosis, both in vitro and in vivo. Network pharmacology identified mTOR as a key target of TSN, and surface plasmon resonance analysis confirmed TSN's direct binding to mTOR, underscoring mTOR's role in TSN's protective effects against ALI. Western blotting showed that TSN inhibits mTOR and its phosphorylation. In vitro, the mTOR activator MHY1485 reversed TSN's protective effects, increasing ER stress, apoptosis, and endothelial permeability. In vivo, TSN and rapamycin synergistically protected against ALI.

Conclusion

This study is the first to demonstrate that TSN protects against ALI by targeting the mTOR pathway, regulating ER stress and apoptosis and mitigating endothelial damage. These findings suggest a novel approach for ALI treatment and underscore TSN's potential clinical value.