Phosgene inhalation injury in mice: Modeling human pathophysiology, biomarker discovery, and therapeutic target identification.

Phosgene gas, also known as choking gas (CG; military designation), has been used in warfare and terrorism and remains a major industrial and transportation hazard. Phosgene inhalation causes severe pulmonary edema, acute lung injury, and high mortality; however, no forensic diagnostic biomarkers or mechanism-based medical countermeasures are currently available. Here, we developed a reproducible mouse model of phosgene-induced acute respiratory distress syndrome (ARDS), identified candidate biomarkers and drug targets, and evaluated pharmacological inhibition of transient receptor potential vanilloid 4 (TRPV4) as a potential countermeasure. 8-9-week-old male and female BALB/c mice were exposed to 20 ppm phosgene for 15 min using a nose-only exposure system. At 8 h post-exposure, bronchoalveolar lavage fluid (BALF), lung, and sensory ganglia were analyzed for inflammatory, vascular, functional, transcriptional, proteomic, and histopathological endpoints. Phosgene exposure increased BALF total protein and albumin, indicating alveolar-capillary barrier disruption, and induced leukocyte influx, pro-inflammatory cytokines, vascular injury and coagulation markers, impaired lung mechanics, airway hyperresponsiveness, and ARDS-like histopathology characterized by septal thickening and intra-alveolar neutrophilic/proteinaceous debris. Multiplex protein profiling identified 63 differentially expressed biomarkers that distinguished phosgene-exposed mice from air controls and captured key mechanisms of toxic inhalation injury, including inflammation, immune activation, endothelial dysfunction, vascular leakage, matrix remodeling, and impaired repair. Many of these proteins are linked to FDA-approved or investigational therapeutics, nominating actionable drug targets for medical countermeasure development. Treatment with the TRPV4 antagonist GSK2220691 attenuated phosgene-induced pulmonary injury, supporting TRPV4 inhibition as a promising mechanism-based therapeutic strategy for phosgene inhalation injury.