Cold stimulated bronchial epithelial cells derived exosomes HMGB1 aggravates bronchial epithelial cells injury.

The aim of this study was to reveal the mechanism of cold stimulation (CS)-bronchial epithelial cells (BECs) derived exosomes (CS-BECs-exo) aggravated sepsis induced acute lung injury (SALI). CS-BECs-exo were separated by differential centrifugation and were characterized. Proteomics, immunoprecipitation, and RAGE knockout (RAGE) mice were used to investigate the mechanism of CS-BECs-exo aggravated SALI. The results of transmission electron microscope (TEM) showed that CS-BECs-exo showed a double-layer membrane structure like a saucer. Nanoparticle tracking analysis (NTA) particle size analysis showed that the average particle size of CS-BECs-exo was 123.6 nm. The results of proteomics showed that the expression level HMGB1 was significantly increased in CS-BECs-exo compared with BECs-exo. CS-BECs-exo significantly increased oxidative stress and inflammatory reaction of SALI. In addition, CS-BECs-exo significantly increased RAGE and decreased the levels of Nrf-2 and OH-1. RAGE knockout (RAGE KO) and silence of RAGE (RAGE siRNA) significantly canceled the effects of CS-BECs-exo on SALI. HMGB1 knockout (HMGB1) and silence of HMGB1 also significantly (HMGB1 siRNA) canceled the effects of CS-BECs-exo on SALI. In conclusion, CS-BECs-exo aggravated ALI in sepsis via HMGB1/RAGE/Nrf-2/OH-1 signal pathway.