Figure 1.

Inhibiting the secretion of intrapulmonary exosomes alleviates septic lung injury. Rats were treated with GW4869 (2.5 μg/g) through airway instillation. CLP procedures were conducted one hour post-treatment, and sham operated rats were used as negative controls. (A) Representative electron micrograph of exosomes purified from the BALF (indicated by white arrows). Scale bars, 200 nm. (B) Western blot assessment of exosomes showing the presence of CD63 and CD9 in BALF-derived exosomes. (C) Quantification of exosomal protein concentration in the BALF of each group of rats. (D) Histopathological examination of lung tissue by HE staining, Scale bars,50 µm. (E) Scoring the pathology of lung tissue damage using the Smith scoring method. (F–H) Changes in lung tissue oedema of rats under different treatments. (F) Evans blue content in lung tissue. (G) The wet/dry weight ratio in lung tissue. (H) The ratio of protein concentration in BALF to plasma. (I) The expression levels of IL-1β and TNF-α in BALF and plasma. (J, K) Survival rate of rats in each group within 7 days and the changes in sepsis score of each group. The Kaplan-Meier method combined with the log-rank test was used to compare multiple populations. Compared with the sham group, *P<0.05; compared with the CLP group, ^#P<0.05; n=10 for the sham group, n=20 for the other groups. (L) Western blot assessment of the expression of epithelial cell-specific marker proteins SP-B and cytokeratin in exosomes derived from BALF and quantitative analysis of the protein grey value. Data are presented as the mean ± S.E.M. **P<0.001, ***P<0.001 compared between two groups. n=6 per group.