Fig 2: A proposed model illustrating the inhibitory effect of R. intestinalis on inflammation and colitis. R. intestinalis increases TSLP expression in IECs expressing TLR5 and induces IL-10 production and TGFß expression in DCs. These cytokines then promote the differentiation of Tregs to inhibit colonic inflammation. TLR5, Toll-like receptor 5; IECs, intestinal epithelial cells; DCs, dendritic cells; Treg, regulatory T cell.

Fig 3: TLR5, TSLP, TGFß and IL-10 levels in the intestine are positively related to R. intestinalis in patients with CD.(a-d) Representative images of IHC detection of colonic TLR5, TSLP, TGFß and IL-10 expression in healthy controls (ctrl) or patients with CD.(e-h) Each section stained using IHC was evaluated, and five images from each slide were randomly selected and measured using ImageJ. The mean densities of TLR5, TSLP, TGFß and IL-10 were statistically analysed (ctrl: n=22; patients: n=24).(i) Comparative analysis of R. intestinalis in the faeces of the healthy controls or the patients with CD.(j-m) The correlations between the levels of TLR5, TSLP, TGFß and IL-10 with R. intestinalis in controls and patients with CD were analysed (Spearman's correlation analysis with two-tailed p values).**p<0.01 and ***p<0.001. Data represent the cumulative results from two or three independent experiments.

Fig 4: FlaA N/C increased radiosensitivity though NF-?B signaling. (A) Immunofluorescence staining showed that TLR5 was expressed in 4T1 cells. Scale bars represent 50 µm. (B) Western blot analysis showed the activation of NF-?B signaling following FlaA N/C treatment. TLR5, toll like receptor 5; Con-IgG, control-immunoglobulin G; DAPI, 4',6-diamidino-2-phenylindole; NF-?B, nuclear factor-?B; P65, RELA proto-oncogene, NF-kB subunit.

Fig 5: TLR5-expressing IECs are required for R. intestinalis-mediated amelioration of colitis in TNBS-induced mice.(a) Schematic illustrating the experimental procedure of BMT. Irradiated WT mice and Tlr5-/- mice were reconstituted with BM from WT or Tlr5-/- donors. After bone marrow reconstitution and SPF standardization, the chimeric mice were presensitized with TNBS administered cutaneously on day 0, administered TNBS solution intrarectally on days 8 and 10, followed by the intragastric administration of the R. intestinalis suspension or 3 consecutive days and then sacrificed for analysis on day 15. Abbreviations: Abx, antibiotics; R.I, R. intestinalis; TNBS, 2,4,6-trintirobenzenesulfonic acid.(b and c) Changes in body weight (b) and DAI score (c) over the last 7 days of administration of TNBS and R. intestinalis in reconstituted mice (n=6). The solid line refers to the TNBS group compared with the control group (WT?WT (TNBS) vs. WT?WT (control), WT?Tlr5-/- (TNBS) vs. WT? Tlr5-/- (control); Tlr5-/-?WT (TNBS) vs. Tlr5-/-?WT (control); Tlr5-/-? Tlr5-/- (TNBS) vs. Tlr5-/-?Tlr5-/- (control)); the dotted line refers to TNBS + R.I group compared with the TNBS group (WT?WT (TNBS + R.I) vs. WT?WT (TNBS); WT?Tlr5-/- (TNBS + R.I) vs. WT?Tlr5-/- (TNBS); Tlr5-/-?WT (TNBS + R.I) vs. Tlr5-/-?WT (TNBS); Tlr5-/-?Tlr5-/- (TNBS + R.I) vs. Tlr5-/-?Tlr5-/- (TNBS)). &&&p<0.001, WT?Tlr5-/- (TNBS + R.I) vs. WT?WT (TNBS + R.I); †p<0.05, Tlr5-/-?WT (TNBS + R.I) vs. WT?WT (TNBS + R.I); ‡p<0.05, ‡‡p<0.01, WT?Tlr5-/- (TNBS + R.I) vs. Tlr5-/-?Tlr5-/- (TNBS + R.I); $$$p<0.001, Tlr5-/-?WT (TNBS + R.I) vs. Tlr5-/-?Tlr5-/- (TNBS + R.I).All control or TNBS groups (WT?WT (control) vs. WT? Tlr5-/- (control) vs. Tlr5-/-?WT (control) vs. Tlr5-/-?Tlr5-/- (control); WT?WT (TNBS) vs. WT? Tlr5-/- (TNBS) vs. Tlr5-/-?WT (TNBS) vs. Tlr5-/-?Tlr5-/- (TNBS)) showed no significant differences.(d and e) Representative images of colon tissues stained with H&E and colon histopathological score (n=6).(f and g) Histograms of Tregs in the reconstituted mice and representative colon flow cytometry plots (gated on CD4+ cells) (n=6).*p<0.05, **p<0.01, ***p<0.001, and ns, not significant. Data represent the cumulative results from two or three independent experiments.