粪菌移植对LPS诱导小鼠重症肺炎的改善作用及分子机制OA

Objective To investigate the effect of fecal microbiota transplantation(FMT)on the TLR4/NF-κB signaling pathway in mice with LPS-induced severe pneumonia.Methods Thirty 6-8-week-old male SPF BALB/c mice were randomly divided into normal control group,severe pneumonia model group(LPS),and FMT group.The mice in LPS group and FMT group were intranasally instilled with LPS into the nasal cavity to establish the model,while the mice in control group were instilled with sterile normal saline.From 6 h after the model establishment,the mice in FMT group were intragastrically gavaged with fecal microbiota suspension for 5 d,while the mice in the other two groups were intragastrically gavaged with the same volume of sterile normal saline.At day 6,the levels of inflammatory cells,and the contents of IL-1β,IL-6,and TNF-α in serum and bronchoalveolar lavage fluid(BALF)were detected.The pathological changes of lung tissue and the scores were observed.The protein expressions of TLR4,p-NF-κB p65,and NF-κB p65 in lung tissue were detected by immunohistochemistry and Western blot.The feces were collected for 16S rRNA sequencing.Results Compared with control group,the percentage of neutrophils in serum and BALF significantly increased in LPS group(P<0.001);the levels of IL-1β,IL-6,and TNF-α in serum were all significantly elevated(P<0.05),while only IL-1β and TNF-α levels in BALF signifi-cantly increased(P<0.05);the inflammatory infiltration in lung tissue was obvious,and the pathological score increased(P<0.01);the expressions of TLR4 and p-NF-κB p65 were up-regulated(P<0.01),while NF-κB p65 showed no significant change;the gut microbiota imbalance was observed.Compared with LPS group,the above inflammatory indicators were significantly reduced in FMT group(P<0.05);the pathological damage of lung tissue was improved,and the score was decreased(P<0.01);the expressions of TLR4 and p-NF-κB p65 were down-regulated(P<0.05),and the gut microbiota structure was restored.Conclusion FMT can improve LPS-induced severe pneumonia in mice by alleviating the pulmonary immune inflammatory response via the inhibition of TLR4/NF-κB pathway.