Targeting the Snail1-ATGL-ferroptosis-EMT axis via AKT-GSK3β signaling: Low-dose colchicine attenuates idiopathic pulmonary fibrosis.

چکیده اصلی

BACKGROUND: The mechanisms underlying colchicine's (COL's) anti-fibrotic effects in idiopathic pulmonary fibrosis (IPF) remain unclear. Ferroptosis-associated redox imbalance and epithelial-mesenchymal transition (EMT) are well-recognized central drivers of IPF progression, yet the upstream regulatory mechanisms linking redox homeostasis to ferroptotic vulnerability remain incompletely elucidated. PURPOSE: This study aimed to clarify the effects and mechanisms of low-dose Colchicine (COL) on ferroptosis-driven EMT in IPF, with a focus on the Snail family transcriptional repressor 1 (Snail1)-adipose triglyceride lipase (ATGL) axis as a novel pathway regulating redox balance and ferroptosis susceptibility. MATERIALS AND METHODS: Public transcriptomic and single-cell RNA sequencing datasets were analyzed to evaluate key gene expression patterns in IPF lung tissues and alveolar epithelial cells, with validation in a bleomycin (BLM)-induced pulmonary fibrosis mouse model. In parallel, transforming growth factor-β (TGF-β)-stimulated lung epithelial cell models were established to investigate ferroptosis- and EMT-related processes using genetic and pharmacological interventions. Chromatin immunoprecipitation and protein interaction assays were further performed to elucidate the underlying transcriptional regulatory mechanisms. RESULTS: ATGL expression was consistently suppressed in alveolar epithelial cells from patients with IPF, as well as in BLM-injured mouse lungs and TGF-β-stimulated mouse lung epithelial (MLE-12) and human bronchial epithelial (BEAS-2B) cells. Complementary gain- and loss-of-function analyses, together with pharmacological inhibition of ATGL activity, demonstrated for the first time that ATGL mitigated ferroptosis-driven EMT in TGF-β-challenged MLE-12 cells by limiting intracellular iron accumulation and lipid peroxidation. Both Snail1 knockdown and low-dose COL upregulated ATGL, thereby inhibiting epithelial ferroptosis and subsequent EMT, whereas ATGL deficiency abrogated these protective effects. Snail1 directly repressed ATGL transcription by recruiting histone deacetylase 1 (HDAC1) and histone deacetylase 2 (HDAC2) to diminish histone acetylation at the Pnpla2 promoter. Pharmacologically, low-dose COL restored ATGL expression by suppressing the AKT-GSK3β-Snail1 signaling axis in MLE-12 cells and was accompanied by reduced Snail1 and increased ATGL expression in mouse lung tissue, ultimately alleviating ferroptosis-associated iron dysregulation, lipid peroxidation, and fibrotic remodeling in vivo. CONCLUSION: These findings identify ATGL as an epithelial checkpoint that modulates ferroptosis susceptibility and EMT under fibrotic stress and reveal Snail1-dependent regulation of ferroptosis as a previously unappreciated noncanonical mechanism of EMT regulation. This study provides novel mechanistic insight into the actions of low-dose COL, supporting its translational relevance in IPF.

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