Faecalibacterium prausnitzii is an anti-inflammatory commensal bacterium identified by gut microbiota analysis of Crohn disease patients

Abstract

A decrease in the abundance and biodiversity of intestinal bacteria within the dominant phylum Firmicutes has been observed repeatedly in Crohn disease (CD) patients. In this study, we determined the composition of the mucosa-associated microbiota of CD patients at the time of surgical resection and 6 months later using FISH analysis. We found that a reduction of a major member of Firmicutes, Faecalibacterium prausnitzii, is associated with a higher risk of postoperative recurrence of ileal CD. A lower proportion of F. prausnitzii on resected ileal Crohn mucosa also was associated with endoscopic recurrence at 6 months. To evaluate the immunomodulatory properties of F. prausnitzii we analyzed the anti-inflammatory effects of F. prausnitzii in both in vitro (cellular models) and in vivo [2,4,6-trinitrobenzenesulphonic acid (TNBS)-induced] colitis in mice. In Caco-2 cells transfected with a reporter gene for NF-kappaB activity, F. prausnitzii had no effect on IL-1beta-induced NF-kappaB activity, whereas the supernatant abolished it. In vitro peripheral blood mononuclear cell stimulation by F. prausnitzii led to significantly lower IL-12 and IFN-gamma production levels and higher secretion of IL-10. Oral administration of either live F. prausnitzii or its supernatant markedly reduced the severity of TNBS colitis and tended to correct the dysbiosis associated with TNBS colitis, as demonstrated by real-time quantitative PCR (qPCR) analysis. F. prausnitzii exhibits anti-inflammatory effects on cellular and TNBS colitis models, partly due to secreted metabolites able to block NF-kappaB activation and IL-8 production. These results suggest that counterbalancing dysbiosis using F. prausnitzii as a probiotic is a promising strategy in CD treatment.

Fig. 1.

F. prausnitzii proportions in the ileal MAM using FISH at the time of surgery and at 6 months according to the endoscopic recurrence status. *, Significant difference, P = 0.03.

Fig. 2.

IL-10 (A), IL-12 (B), and IFN-γ (C) response of human PBMCs of six distinct individual donors to stimulation with RPMI medium and five bacterial strains. The values are expressed as the mean ± SEM in pg/ml for cytokines and in percentages for IL-10/IL-12 ratio (D). Different asterisks (*) indicate significant differences (*, P < 0.05; **, P < 0.01; ***, P < 0.003).

Fig. 3.

F. prausnitzii supernatant exerts antiinflammatory effects on Caco-2 cells. (A) Modulation of IL-1β-induced IL-8 secretion by Caco-2 cells in contact with F. prausnitzii, its component, or its supernatant. Cells were stimulated or not with IL-1β at 15 ng/ml. IL-8 secretion is expressed as picograms per micgrogram of proteins. The values are expressed as the mean ± SEM in pg/μg of proteins. (B) Effects of F. prausnitzii on Caco2 cells stably transfected with an NF-κB SEAP reporter gene with or without stimulation with IL-1β. SEAP activity is expressed as optical density (OD). Different asterisks (*) indicate significant differences (*, P < 0.05; **, P < 0.01; ***, P < 0.003; ****, P < 0.001).

Fig. 4.

Effects of intragastric administration of F. prausnitzii and its supernatant on TNBS-induced colitis in BALB/c mice considering (A) Wallace macroscopic score, (B) Ameho histologic score, (C) colon length, and (D) weight. Each group included 9 or 10 mice. The values are expressed as the mean ± SEM. Different asterisks (*) indicate significant differences (*, P < 0.05; **, P < 0.01).

Fig. 5.

Quantification using ELISA of TNF-α (A), IL-12 (B), and IL-10 (C) in colons obtained 48 h after TNBS colitis induction. The values are expressed in pg/μg of total proteins as the mean ± SEM. Different asterisks (*) indicate significant differences (*, P < 0.05; **, P < 0.01; ***, P < 0.003; ****, P < 0.001).

Fig. 6.

Quantification using real-time qPCR of dominant and subdominant bacteria in the fecal microbiota of mice 48 h after TNBS induction of colitis. Noncolitis control group received PBS intragastrically and 0.9% NaCl/ethanol (50:50 vol/vol) intrarectally. The values are expressed as the mean of Log₁₀ bacteria per gram of stool ± SEM. Different asterisks (*) indicate significant differences (*, P < 0.05; **, P < 0.01; ***, P < 0.003; ****, P < 0.001).

Fig. 7.

Protective effects of i.p. administration of F. prausnitzii and its supernatant on mice after TNBS challenge. Each group included 10 mice. Statistical analysis was performed using the log rank test.