Intranasal administration of Clostridium butyricum and its derived extracellular vesicles alleviate LPS-induced acute lung injury

Acute lung injury (ALI) is associated with high morbidity and mortality rates. However, its clinical treatment is limited. Currently, the treatment of lung diseases by regulating the lung microbiota has become a research hotspot. In this study, we investigated the protective effects of the intranasal administration of Clostridium butyricum and its derived extracellular vesicles (EVs) against lipopolysaccharide (LPS)-induced ALI. The results demonstrated that compared with the LPS group, the pre-treatment group with C. butyricum and its EVs reduced the expression of pro-inflammatory cytokines and alleviated the symptoms in ALI mice by inhibiting the TLR4/MyD88 signaling pathway. Moreover, C. butyricum and its derived EVs inhibited the expression of apoptosis-related proteins and increased the expression of lung barrier proteins. Additionally, the intervention of C. butyricum changed the composition of the pulmonary microbiota. At the species level, LPS significantly increased the relative abundance of Acinetobacter johnsonii, while C. butyricum reversed this effect. In conclusion, these data demonstrate that intranasal administration of C. butyricum and its EVs can prevent LPS-induced ALI by reducing inflammation, inhibiting apoptosis, and improving lung barrier function. Additionally, C. butyricum regulated the pulmonary microbiota of mice to alleviate LPS-induced ALI.IMPORTANCEThe disorder of pulmonary microbiota plays an important role in the progression of acute lung injury (ALI). However, very few studies have been conducted to treat ALI by modulating pulmonary microbiota. In this study, the diversity and composition of pulmonary microbiota were altered in lipopolysaccharide (LPS)-induced ALI mice, but the ecological balance of the pulmonary microbiota was restored by intranasal administration of Clostridium butyricum. Moreover, the study reported the mechanism of C. butyricum and its derived extracellular vesicles for the treatment of LPS-induced ALI. These results reveal the importance of pulmonary microbiota in ALI disease. It provides a new approach for the treatment of ALI with new-generation probiotics.