Epithelial Atg5 Deficiency Intensifies Caspase-11 Activation, Fueling Extracellular mtDNA Release to Activate cGAS–STING–NLRP3 Axis in Macrophages During Pseudomonas Infection

Abstract

Pseudomonas aeruginosa (P. aeruginosa) infections pose a significant threat to public health, underscoring the need for deeper insights into host cellular defenses. This study explores the critical role of autophagy-related protein 5 (ATG5) in lung epithelial cells during P. aeruginosa infection. Single-cell RNA transcriptomics revealed a pronounced enrichment of autophagy pathways in type II alveolar epithelial cells (AEC2). Using a conditional Atg5 knockout murine model, we demonstrated that ATG5 deficiency in AEC2 compromises survival, hampers bacterial clearance, and increases pathogen dissemination. Additionally, the loss of ATG5 exacerbated inflammatory responses, notably through the activation of the AKT/PI3K/NF-κB axis and pyroptosis, which culminated in severe lung injury and epithelial barrier disruption. Mechanistically, the absence of ATG5 disrupted mitophagy, leading to intensified mitochondrial damage. This exacerbated condition coupled with the activation of gasdermin D (GSDMD) by the noncanonical caspase-11, enhancing the release of mitochondrial DNA (mtDNA), which in turn activated cGAS–STING–NLRP3 signaling in macrophages. These findings highlight the essential role of ATG5 in modulating immune responses and suggest potential therapeutic targets for managing P. aeruginosa-induced pulmonary infections.