Fig 1.
Broad-spectrum antibiotic treatment abolishes T. spiralis-evoked inhibition of colitis.
(A) T. spiralis infection, ABX treatment and DSS- induced colitis schedule, mice were orally gavaged with T. spiralis or PBS, 35 days later, some of the mice were treated with ABX daily for 14 days, then were given drinking water containing 2.5% (wt/vol) DSS ad libitum for 7 days, and others left untreated as controls. After a further 3 days of distilled water fed, mice were sacrificed and samples were obtained and processed. (B) Weight change in percent. (C) The changes in DAI, scored from diarrhea, bleeding and body weight loss. (D) The histopathological changes in the colon tissues were examined by H&E staining, the black bar indicates 200 μm. (E) Histopathological scores were determined for the colon tissue samples. The data shown are means ± SD. Representative results from one out of three independent experiments with n = 5. *, $ P< 0.05 compared to DSS and ABXTs-DSS, respectively; ####P < 0.0001 versus the respective control group. ABX: antibiotic cocktail of ampicillin (1g/L), vancomycin (0.5g/L), neomycin (1g/L), and metronidazole (1g/L) treated; ABXTs: T. spiralis infected and antibiotic treated; Ts: T. spiralis infected; DSS: DSS-induced colitis; Ts-DSS: T. spiralis infected and DSS induced colitis; ABX-DSS: antibiotic treated and DSS induced colitis; ABXTs-DSS: T. spiralis infected, antibiotic treated and DSS induced colitis.
Fig 2.
T. spiralis infection changes gut microbiota composition in mice.
Colon contents from mice post 5 weeks of T. spiralis infection and control mice were collected and analyzed by using 16S rRNA gene sequencing. (A) The number of OTU, (B) Alpha diversity analysis (Chao 1 and ACE index), data are shown as Median, maximum, minimum, upper quartile and lower quartile. (C) Beta diversity analysis (PCoA based on Binary-Jaccard), (D) the relative abundance of OTUs at phylum and (E) the relative abundance of the top 20 genus in T. spiralis- infected mice and control mice. (F) The ratio of Muribaculum, unclassified_Muribaculaceae, unclassified_Oscillospiraceae and Alistipesin between groups, data are shown as the means ± SD. *P <0.05, **P<0.001 versus the control group. (G) Microbial community functions were predicted by PICRUSt2 using STAMP. Ts: T. spiralis infected.
Fig 3.
Cohousing with T. spiralis- infected mice ameliorates the severity of colitis.
(A) Infection, cohousing and DSS-induced colitis schedule. The mice were gavaged with T. spiralis 5 weeks prior to cohousing, and subsequently induced colitis after 4 weeks of cohousing. (B) Weight change in percent. (C) The changes in DAI, scored from diarrhea, bleeding and body weight loss. (D) The histopathological changes in the colon tissues were examined by H&E staining, the black bar indicates 200 μm. (E) Histopathological scores were determined for the colon tissue samples. The data shown are means ± SD. Representative results from one out of two independent experiments with n = 4. *P <0.05, **P <0.01, ***P <0.001 versus the DSS group. cocontrol: normal mice cohoused with T. spiralis -infected mice; DSS: DSS-induced colitis; coDSS: normal mice cohoused with T. spiralis- infected mice and DSS-induced colitis.
Fig 4.
Cohousing with T. spiralis- infected mice induces alterations in the composition of the gut microbiome.
(A) Alpha diversity analysis (Chao 1 and ACE index), data are shown as Median, maximum, minimum, upper quartile and lower quartile. (B) Beta diversity analysis (PCoA based on Binary-Jaccard). The relative abundance of the top 10 phyla (C) and the top 20 genus (D) in mice. (E) The ratio of Muribaculum, unclassified_Muribaculaceae, unclassified_Oscillospiraceae, Alistipesin and unclassified_Clostridia_UCG_014 between groups control mice and mice cohousing with T. spiralis- infected mice, data are shown as the means ± SD. *P <0.05, **P<0.001 versus the control group. cocontrol: normal mice cohoused with T. spiralis- infected mice.
Fig 5.
Feces from T. spiralis- infected mice contain increase amounts of SCFAs.
(A) PCA score plot and (B) OPLS-DA score plot shown the difference of control mice and T. spiralis -infected mice. (C) Volcano map of SCFAs by OPLS-DA model. The abscissa represents Value Importance in Projection (VIP); the ordinate represents the level of significant difference (−Log10 (p)). (D) Permutation Test was performed to verify the validity of OPLS-DA model. (E) Receiver Operating Characteristic (ROC) curve by Support Vector Machines (SVM). (F) Heat-map of SCFAs between control mice and T. spiralis- infected mice. (G) Box plot of propionic acid, data are shown as Median, maximum, minimum, upper quartile and lower quartile. (H) Volcano map of SCFAs. The abscissa represents the logarithm of the relative content fold change (Log2(FC)) of a metabolite in two groups; the ordinate represents the level of significant difference (−Log10(p)). (I) Heat-map of SCFAs between DSS- treated alone group (DSS) and T. spiralis- infected DSS- treated group (Ts_DSS). *P <0.05 compared to control.
Fig 6.
T. spiralis infection results in the regulation of both pro-inflammatory and immunoregulatory cytokine responses during DSS- induced colitis by modulating the gut microbiome.
Mice infected with T. spiralis were subjected to antibiotic treatment or cohousing with control mice, followed by administration with or without DSS. (A) Lymphocytes were prepared from MLN and stimulated by anti-CD3 antibody. IL-10 in the supernatants were analyzed by ELISA kits. (B-D) The colonic tissues were collected; and the mRNA expression of IL-10, IL-1β and IL-6 was determined using RT-qPCR. The data shown are means ± SD (n = 4–5 mice per group) from one of three experiments performed showing similar results. *P <0.05 between the indicated groups; #P <0.05, ##P <0.01, ###P <0.001, ####P <0.0001 versus the respective control group; & P <0.05 versus the DSS group; $ P <0.05 versus the Ts-DSS group. ABX: antibiotic treated; Ts, T. spiralis infected; ABXTs: T. spiralis infected and antibiotic treated; DSS: DSS induced colitis; Ts-DSS: T. spiralis infected and DSS induced colitis; ABX-DSS: antibiotic treated and DSS induced colitis; ABXTs-DSS: T. spiralis infected, antibiotic treated and DSS induced colitis; cocontrol: normal mice cohoused with T. spiralis -infected mice; coTs: T. spiralis infected and cohoused; coDSS: normal mice cohoused with T. spiralis infected mice and DSS induced colitis; coTs-DSS: T. spiralis infected, cohoused and DSS induced colitis.
Fig 7.
T. spiralis infection modulates epithelial barrier properties during DSS- induced colitis by modulating the gut microbiome.
Mice infected with T. spiralis were subjected to antibiotic treatment or cohousing. (A) Goblet cells were stained with PAS, and (B) the number of goblet cells was calculated as the average score of 10 random fields from each mouse. The data shown are means ± SD (n = 4–5 mice per group). *P < 0.05 between the indicated groups; ##P < 0.01, ####P < 0.0001 versus the respective control group; & P < 0.05 versus the DSS group; $ P < 0.05 versus the Ts-DSS group. ABX: antibiotic treated; Ts, T. spiralis infected; ABXTs: T. spiralis infected and antibiotic treated; DSS: DSS induced colitis; Ts-DSS: T. spiralis infected and DSS induced colitis; ABX-DSS: antibiotic treated and DSS induced colitis; ABXTs-DSS: T. spiralis infected, antibiotic treated and DSS induced colitis; cocontrol: normal mice cohoused with T. spiralis -infected mice; coTs: T. spiralis infected and cohoused; coDSS: normal mice cohoused with T. spiralis infected mice and DSS induced colitis; coTs-DSS: T. spiralis infected, cohoused and DSS induced colitis.