Mechanical stress promotes excessive NETs and exacerbates acute lung injury via Piezo1-mediated mitochondrial dysfunction.

Acute lung injury (ALI) is a respiratory insufficiency syndrome precipitated by factors such as infection, sepsis, or systemic trauma. Excessive polymorphonuclear neutrophil (PMN) infiltration and activation represent the hallmark cellular features of early-stage ALI. However, it remains poorly understood how the pulmonary biomechanical microenvironment, remodeled by ALI-induced diffuse edema, decreased lung compliance, and mechanical ventilation, modulates PMN hyperactivation. Using a sequential model of LPS-induced lung injury and differential mechanical ventilation combined with an in vitro cell compression system, we demonstrate that PMN Piezo1 senses pathological physical strain and orchestrates pro-inflammatory responses. Single-cell RNA sequencing identified a mechanosensitive "mitochondrial-stress" PMN cluster that expands during ALI, defined by profound mitochondrial damage and elevated ROS production. Mechanistically, Piezo1 transduces mechanical stimuli into cytosolic Ca2+ overload, triggering a cascade of mitochondrial dysfunction, ROS overproduction, and mtDNA leakage, thereby driving excessive NETs and lung injury. Notably, pharmacological blockade of Piezo1 effectively suppresses NETs and alleviates ALI. Our study demonstrates that, alongside inflammatory cues, Piezo1-mediated mechanosensing is a fundamental mechanism driving pathological PMN overactivation, identifying it as a promising therapeutic target for ALI.