ABSTRACT
OBJECTIVE To study the improvement effects of Shaoyao gancao decoction （SGD） on acute lung injury （ALI） in rats and its effects on the intestinal flora. METHODS Sixty SD rats were randomly divided into normal group （CON group， normal saline）， model group （MOD group， normal saline）， positive control group （DEX group， 5 mg/kg dexamethasone）， SGD low-dose， medium-dose and high-dose groups （SGD-L， SGD-M， SGD-H groups， 5.8， 11.6， 23.2 g/kg， calculated by crude drug）， with 10 rats in each group. Each group was given relevant medicine 10 mL/kg intragastrically， for 7 consecutive days. Thirty minutes after the last administration， CON group was given constant volume of normal saline via airway infusion， and other groups were given lipopolysaccharide （5 mg/kg） via airway infusion to induce ALI model. After 12 hours of modeling， the lung tissue wet/dry weight ratio was calculated， and the contents of interleukin 1β （IL-1β）， IL-6 and tumor necrosis factor α（TNF-α） in rat bronchial alveolar lavage fluid （BALF） were all detected； the pathological changes of lung tissue were observed after hematoxylin-eosin staining. The intestinal flora of rat feces was analyzed by 16S rRNA sequencing technology， and the correlation of differential bacteria genera with inflammatory factors was also analyzed. RESULTS Compared with MOD group， the infiltration of inflammatory cells in the lung tissue of rats in each SGD dose group was decreased， and the thickening of alveolar septum and pulmonary edema improved； lung tissue wet/dry weight ratio， the levels of IL-1β， IL-6 and TNF-α in BALF significantly decreased （P＜0.05 or P＜0.01）. SGD （low dose） could improve the intestinal flora disorder in ALI rats， restore the diversity and richness of intestinal flora， regulate the structure of flora， reduce the abundance of Lactobacillus， Streptococcus and Escherichia-Shigella， and increase the abundance of Firmicutes， Lachnospira， Ruminococcus， Clostridia，Dubosiella and Akkermansia. Through correlation analysis， it was found that the relative abundance of Lactobacillus， Streptococcus and Escherichia-Shigella was positively related to the levels of inflammatory factor IL-1β， IL-6 and TNF-α （P＜0.05 or P＜0.01）. The relative abundance of Lachnospira， Dubosiella， Firmicutes was significantly negatively correlated with the levels of inflammatory factors mentioned above （P＜0.05 or P＜0.01）. CONCLUSIONS SGD may improve ALI by reducing lung tissue injury and inflammatory response and regulating flora structure in rats.