[Clinical study on the relationship between the exosomes in bronchoalveolar lavage fluid and plasma and the severity of lung injury and outcome in early acute respiratory distress syndrome patients].

Objective: To investigate the relationship between the levels of exosomes in bronchoalveolar lavage fluid (BALF) and plasma and the severity of lung injury and its outcome in patients with acute respiratory distress syndrome (ARDS). Methods: Patients who were admitted to the Department of Critical Care Medicine, Zhongda Hospital Affiliated to Southeast University and received invasive mechanical ventilation were selected from August 2020 to April 2021, and they were divided into ARDS group and non-ARDS group. Finally, 33 ARDS patients were included, including 18 males and 15 females, aged (65.5±15.5) years; 10 non-ARDS patients, 8 males and 2 females, aged (57.2±15.3) years. The BALF and plasma of the two groups of patients were collected within 24 hours after enrollment, and the total exosomes of the samples were collected by ultracentrifugation. Nanoparticle tracking analysis (NTA) was used to detect and compare the differences in exosome content between the two groups. Correlation of content with the severity and prognosis of lung injury in ARDS patients. Results: There was no significant difference in gender and age between ARDS group and non-ARDS group (both P>0.05). The exosome in plasma of ARDS group was significantly higher than that of non-ARDS group [(25.3±1.2)/ml vs (24.2±1.6)/ml, P=0.031], while the exosomes in BALF of ARDS group was also higher than that of non-ARDS group [(26.5±1.6)/ml vs (24.6±1.1)/ml, P=0.001]. The exosomes in BALF of patients with ARDS caused by intrapulmonary causes was higher than that in ARDS group caused by extrapulmonary causes [(26.9±1.5)/ml vs (25.2±0.9)/ml, P=0.01], and the infection caused by bacterial shows that the highest exosome level in BALF. The exosomes in the BALF of the mild ARDS group was significantly lower than that of the severe ARDS group [(25.7±1.3)/ml vs (27.2±1.5)/ml, P=0.038]; the exosomes in BALF of ARDS patients was negatively correlated with P/F ratio (r=-0.38, P=0.03); and it was positively correlated with Murray lung injury score (r=0.47, P=0.01). However, the static compliance levels, length of hospital stay, duration of mechanical ventilation, and 28-day outcome were not associated with the exosomes in BALF. Conclusion: Compared with non-ARDS patients, ARDS patients have significantly higher levels of exosomes in BALF and plasma, there is a certain correlation between exosomes derived from BALF and the severity of lung injury in ARDS.