Activation of aryl hydrocarbon receptor by cigarette smoke induces oxidative stress, autophagy impairment and cellular senescence.

INTRODUCTION: Cellular senescence is a core pathogenic mechanism of chronic obstructive pulmonary disease (COPD), and cigarette smoke (CS) acts as its primary risk factor. However, the molecular cascade linking CS exposure to pulmonary cellular senescence remains poorly defined. The aryl hydrocarbon receptor (AhR), a ligand-activated transcription factor triggered by CS-derived chemicals, has an unclarified function in smoke-induced lung cell senescence. This study aimed to verify whether AhR mediates CS-elicited pulmonary senescence through regulating oxidative stress and autophagy, and to elucidate the complete downstream signaling cascade. METHODS: We established an 8-week whole-body CS exposure rat COPD model and treated human bronchial epithelial BEAS-2B cells with cigarette smoke extract (CSE). Multiple detection approaches were applied to assess lung pathological lesions, cellular senescence, autophagic flux and intracellular reactive oxygen species (ROS). We further performed transcriptomic sequencing on rat lung tissues and mined three public human COPD Gene Expression Omnibus (GEO) datasets to screen key differential genes. Rescue experiments with rapamycin (autophagy activator), N-acetylcysteine (NAC, ROS scavenger) and CH223191 (specific AhR antagonist) were conducted to validate causal relationships among AhR, ROS, autophagy and senescence. RESULTS: In vivo CS exposure induced typical COPD-like pathological alterations and prominent cellular senescence in rat lungs. In vitro CSE treatment triggered dose-dependent senescence in BEAS-2B cells, accompanied by impaired autophagic flux and excessive ROS overproduction; rapamycin and NAC separately reversed these two phenotypes. Both in vivo and in vitro data confirmed robust activation of the AhR pathway, evidenced by significant upregulation of AhR target genes CYP1A1 and CYP1B1. Pharmacological inhibition of AhR via CH223191 suppressed ROS accumulation, restored defective autophagy, and ultimately alleviated CSE-induced cellular senescence. CONCLUSIONS: CS activates pulmonary AhR signaling, which sequentially drives excessive ROS generation, autophagic flux impairment and irreversible lung epithelial senescence. The AhR-ROS-autophagy axis represents a novel pathogenic pathway mediating smoke-related lung aging.