Protective effects and mechanisms of Faecalibacterium prausnitzii in experimental colitis in rats

Objective To investigate the protective effects and mechanism of Faecalibacterium prausnitzii (Fp) and its products in 2,4,6-trinitrobenzene sulfonic acid (TNBS) induced colitis rats.Methods A total of 40 Sprague-Dawley rats were divided into healthy control group,colitis model group,Fp supernatant group,Fp bacteria group and Bifidobacterium longum (B.longum) group.The rats of the later four groups were enemaed with TNBS to establish the model.At five days before and one day after modeling,the rats were gavaged with phosphate buffer saline (PBS),the supernatant of Fp,live Fp bacteria and live B.longum respectively.Rats were executed at 48 hour after modeling.The colon tissues were taken for pathology examination.The content of short-chain fatty acids (SCFA) in fecal was tested by gas chromatography.The plasma level of interleukin-10 (IL- 10),interleukin-12 ( IL-12),interleukin-17 (IL-17) and interleukin-23 (IL-23) were detected by enzyme-linked immunosorbnent assay (ELISA) and the expression of IL-17 in intestinal mucosal tissues was measured by immunohistochemistry.The data were analyzed by one way ANOVA.Results Compared with the healthy control group,the rats of colitis group suffered serious weight loss and their intestinal pathology score increased [(193.57±14) g vs (170.25±19.18) g,(1.00±0.99) vs (3.34±0.38),t=2.83 and 7.55,all P value＜0.05].The Fp supernatant group showed protective effects in terms of weight and intestinal pathology score [(187.00± 14.67) g,(2.50±0.44),t=2.1 and 2.9,all P＜0.05].Compared with healthy control group,the plasma and colon tissue IL-17 concentration of colitis model group increased (16.61 pg/ml±2.45 pg/ml vs 20.47 pg/ml± 1.45 pg/ml,0.83±0.98 vs 5.14±0.90) (all P＜0.05).Compared with the colitis model group,the plasma and colon tissue IL-17 concentration of Fp supernatant group decreased ( 17.54 pg/ml± 1.51 pg/ml and 2.86±0.69).Conclusion Fp can regulate immune response and suppress rat colonic inflammation,which may be related with the expression of IL-17. Key words: Symbiosis;  Colitis;  Microbiology;  Trinitrobenzenesulfonic acid;  Interleukin-17