Abstract:

Objective To explore the effect of anti-inflammatory decoction on gut microbiota of rats with septic acute lung injury (ALI) by regulating the Toll like receptor 4 (TLR4)/TIR-domain-containing adaptor inducing interferon-β (TRIF) pathway. Methods Rats were stochastically separated into the sham group, the septic ALI group, the anti-inflammatory decoction group (intragastric administration of 14 g/kg anti-inflammatory decoction once a day for 3 days before modeling and within 1 hour after modeling) and the necrosis inhibition agent Necrostatin-1 (Nec-1) group (intraperitoneal injection of 0.6 mg/kg Nec-1 once a day for 3 days before modeling and within 1 hour after modeling), with 10 rats in each group. The septic ALI group and the sham group were given an equal amount of physiological saline by gavage once a day. The lung function of each group of rats [forced vital capacity (FVC), forced expiratory volume at 0.3 seconds (FEV0.3), peak expiratory flow rate (PEF)] were measured. ELISA was used to detect serum levels of TNF-α, IL-1β and IL-6. Fecal gut microbiota was detected. HE staining was used to detect pathological changes in rat lung tissue and small intestine tissue. Western blot assay was used to detect TLR4 and TRIF proteins in lung tissue and small intestine tissue. Results Compared with the sham group, obvious alveolar atrophy, thickening of the alveolar walls, pulmonary interstitial edema, extensive infiltration of inflammatory cells, shortening and detachment of intestinal villi, deformation of crypt structures and abundant infiltration of inflammatory cells were observed in the sepsis ALI group. It was also found that lung function declined (FVC, FEV0.3/FVC and PEF decreased), the serum expression levels of inflammatory factors TNF-α, IL-1β and IL-6 increased, intestinal flora imbalance (decreased counts of bifidobacterium and lactobacillus and increased counts of Escherichia coli) and the protein expressions of TLR4 and TRIF proteins in lung tissue and small intestine tissue increased (P<0.05). The anti-inflammatory agent group and Nec-1 group showed reduced lung and small intestine tissue damage, less inflammatory cell infiltration and effectively reversed the changes of the above indicators in the sepsis ALI group, and the Nec-1 group had a better effect (P<0.05). Conclusion Anti-inflammatory decoction can improve the distribution of gut microbiota in septic ALI rats by inhibiting TLR4/TRIF pathway.

Key words: sepsis, acute lung injury, Toll-like receptor 4, gastrointestinal microbiome, TIR-domain-containing adaptor inducing interferon-β, anti-inflammatory decoction