Role and mechanism of IL-6/STAT3/Th17 signaling pathway in the intervention of forsythia in acute lung injury of septic rats

Abstract

Objective: To investigate the mechanism of interleukin-6 (IL-6) /signal transducers and activators of transcriptional 3 (STAT3) /helper T cell 17 (Th17) signaling pathway in lung injury of rats with sepsis intervened by forsythia, with a view to provide experimental basis for the role and mechanism of forsythia in the treatment of sepsis. Methods: In July 2021, 30 healthy Wistar male rats were selected and randomly divided into sham operation group, model group and treatment group, with 10 rats in each group. The rat model of sepsis was established by cecal ligation and puncture. 2 h after recovery, the rats were given traditional Chinese medicine forsythia orally, twice a day at an interval of 12 h. The wet/dry mass ratio (W/D) of lung tissue was detected 24 h after surgery. The morphological changes of lung tissue were detected by HE staining. Flow cytometry was used to detect Th17 population in peripheral blood. The expression levels of IL-6 and interleukin-17A (IL-17A) in serum were determined by enzyme-linked immunosorbent assay. The mRNA expression levels of IL-17A and IL-6 in lung tissues were detected by reverse transcription-polymerase chain reaction. The expression levels of STAT3 and IL-17A in lung tissue were determined by Western blotting. Results: Compared with model group, the W/D of lung tissue in treatment group was decreased, and the difference was statistically significant (P<0.05). HE staining of lung tissue showed that compared with the model group, the degree of lung lesion and injury was reduced in the treatment group. Compared with sham operation group, the proportion of Th17 cells in CD4 lymphocytes in peripheral blood of rats in model group was significantly increased (P<0.05). Compared with model group, the proportion of Th17 cells in CD4 lymphocytes in peripheral blood of rats in treatment group was significantly decreased (P<0.05). Compared with sham operation group, peripheral blood serum IL-6 and IL-17 of rats in model group were significantly increased (P<0.05). Compared with model group, IL-6 and IL-17 in peripheral blood serum of rats in treatment group were decreased (P<0.05). Compared with sham operation group, the expressions of IL-17A and IL-6 mRNA in lung tissue of model group were significantly increased (P<0.05). Compared with model group, the expressions of IL-17A and IL-6 mRNA in lung tissue of rats in treatment group were significantly decreased (P<0.05). Compared with sham operation group, the protein expressions of STAT3 and IL-17A in lung tissue in model group were significantly increased (P<0.05). Compared with model group, the pritein expressions of STAT3 and IL-17A in lung tissue in treatment group were significantly decreased (P<0.05) . Conclusion: Forsythia plays a role in alleviating lung injury by down-regulating the expressions of the signaling pathway IL-6/STAT3/Th17, which providing a new target for the treatment of sepsis induced lung injury.