Abstract

Ammonia (NH₃), a widespread agricultural emission, poses substantial risks to both humans and livestock through respiratory injury. However, the molecular mechanisms underlying ammonia-induced pulmonary damage remain poorly defined, and targeted interventions are unavailable. Using broiler chickens and primary alveolar type II (AT-II) cells, we investigated pathogenic pathways and potential protective agents. Exosomes derived from ammonia-exposed AT-II cells (NH₃-exo) were enriched in miR-20a-5p, which directly targeted PTEN, activated the AKT/mTOR pathway, and impaired autophagic flux, thereby intensifying inflammation and apoptosis. Depletion of miR-20a-5p mitigated these effects in vitro and in vivo. Screening of six classes of natural compounds identified luteolin (flavonoid) and berberine (alkaloid) as the most effective protectants, restoring autophagic flux and reducing inflammatory and apoptotic responses, similar to rapamycin. This study identifies exosomal miR-20a-5p as a key mediator of ammonia toxicity and highlights flavonoids and alkaloids as promising natural candidates for mitigating ammonia-induced respiratory injury, with implications for agricultural and environmental health.