- Research article
- Open Access
- Open Peer Review
Butyrate inhibits interleukin-17 and generates Tregs to ameliorate colorectal colitis in rats
© The Author(s). 2016
- Received: 4 January 2016
- Accepted: 21 July 2016
- Published: 30 July 2016
Butyrate is an energy source for colonocytes that is formed by bacterial fermentation of dietary fiber in the colon and that exerts broad anti-inflammatory activities. Although the administration of butyrate improves homeostasis in patients and ameliorates IBD (Inflammatory Bowel Disease)-related lesions and symptoms, the anti-inflammatory mechanisms of butyrate still remain unclear. To explore the impact of butyrate on Treg (Regulatory T cell)/Th17 (T helper 17 cell) differentiation and colitis in rats.
The effect of butyrate on the expression of markers related to both Tregs and Th17 cells were determined in human monocytes as well as a rat model of colitis induced by 2,4,6-trinitrobenzene sulfonic acid. Rats were treated with butyrate in vivo, whereas the rat splenocytes and human monocytes were treated in vitro.
We found that butyrate administration increased peripheral blood Treg cell levels as well as plasma levels of anti-Th17 cytokines (IL-10 and IL-12). Butyrate administration further suppressed IL-17 levels in both plasma and colonic mucosa, and ameliorated colonic colitis lesions in rats. This promotion of Treg activity and inhibition of IL-17 release was also observed in human venous monocytes and rat splenocytes in vitro.
Our results suggest that butyrate plays a key role in regulating the Treg/Th17 balance and ultimately protects the colon mucosa against the development of IBD.
- Inflammatory bowel disease
Inflammatory bowel disease (IBD) consists of a group of disorders characterized by recurrent inflammation in the gastrointestinal tract. The two most common forms of IBD are ulcerative colitis (UC) and Crohn’s disease (CD). While the etiology of IBD remains uncertain, it has been hypothesized that an undesired intestinal mucosal immune response to luminal contents contributes to the onset of IBD in a genetically predisposed patient .
CD4+ T helper (Th) cells regulate immunity and inflammation through antigen-dependent activation and cytokine-dependent differentiation into functional T cell subsets. T helper 17 (Th17) cells are unique pro-inflammatory Th cells identified by retinoic acid receptor-related orphan receptor gamma t (RORγt) and interleukin-17 (IL-17) . The IL-23/Th17/IL-17 pathway plays an important role in regulating IBD, and studies have found that Th17 levels are increased in both the colonic mucosa and serum of IBD patients . Other T cells that differentiate from Th cells include regulatory T cells (CD4+CD25+FoxP3+ Treg), which play a key role in modulating the immune response . Tregs are defined by the expression of both surface CD4+CD25+ and the intracellular transcription factor, FoxP3, which plays a key role in regulating Treg activity . Tregs regulate the homeostasis of the intestinal immune system by promoting anti-inflammatory cytokine production, including interleukin-10 (IL-10), and exerting dominant negative regulation of other T helper cells such as Th17 . Tregs both produce and respond to TGF-β, an anti-inflammatory cytokine that plays an important role in maintaining Treg activity . IL-6, an important signaling protein for maintaining the Treg/Th17 balance, suppresses Treg maturation and promotes a predominantly Th17 mediated pro-inflammatory response .
Short-chain fatty acids (SCFAs) are formed by bacterial fermentation of non-starch polysaccharides (NSP), such as dietary fiber in the colon . Butyrate is mostly produced by Faecalibacterium prausnitzii (F. prausnitzii) and serves as an energy source for colonocytes. It appears to exert a promising anti-inflammatory effect by influencing immune cell migration, cytokine expression, and other cellular processes (eg. proliferation, activation and apoptosis) . Studies in UC patients have suggested that both the administration of butyrate and the stimulation of luminal butyrate production by the ingestion of dietary fiber have an ameliorating effect on intestinal inflammation and related symptomology .
Although the administration of butyrate improves IBD-related lesions and symptoms, the exact anti-inflammatory mechanism remains unclear, and its impact on Treg/Th17 differentiation has not yet been examined. Therefore, the hypothesis of this study is that the administration of butyrate can ameliorate lesions and symptoms of colorectal UC in rats by inhibiting Th17 generation and promoting Tregs.
Characteristics of the study population
Control (N = 10)
UC (N = 7)
p > 0.05
Median (IQR) age (years)
p > 0.05
Median (IQR) duration of disease (years)
Median (IQR) BMI
p > 0.05
5-Aminosalicylic acid (%)
Remission (SCCAI Score < 5)
Active (SCCAI Score ≥ 5)
Modeling of colorectal colitis in rats and treatment
The rats (Sprague–Dawley, 7 weeks, males) were induced by TNBS administration . Briefly, the TNBS (Sigma) solution was slowly administered in the colon (100 mg/kg body weight) via a 4.7 mm-diameter catheter. The control was administered with vehicle. After TNBS-administration, the rats were gavaged daily with sodium butyrate (Sigma) solution (0.5 mM/kg body weight) for 20 consecutive days. The control was administered with vehicle. The rats were weighed at the indicated time and killed using ether exposure at day 21. The colon specimens were stained with hematoxylin and eosin, and lesions were analyzed using the modified Neurath Scoring criteria  (briefly, 0 = no inflammation; 1 = very low level of leucocyte infiltration; 2 = low level of leucocyte infiltration; 3 = high level of leucocyte infiltration, high vascular density, thickening of the colon wall; 4 = transmural leucocyte infiltrations, loss of goblet cells, high vascular density, thickening of the colon wall).
Short-chain fatty acids (SCFAs) assay
Fresh faecal samples were collected and stored in at −80 °C. Faecal samples were mixed with water and centrifuged. The supernatant was filtered and mixed with ether and sulfuric acid. After high speed centrifugation, the ether layer was collected and measured in the Agilent 6890 N Gas Chromatograph Machine for SCFA concentrations.
Colon specimens were fixed in 4 % formalin and embedded in paraffin. The sections were were incubated with rabbit anti-rat IL17 antibodies (Abcam) and then treated with immunoperoxidase using the DAB kit (Zsbio). Sections were scored in a blind manner using a protocol modified from Brown & Wahl .
Peripheral blood mononuclear cell (PBMC) culture
PBMCs were isolated from the venous blood of healthy donors . The cells were subsequently suspended in complete medium (2 × 106 cells/ml) and seeded in a 24-well plate (2 × 106 cells/well). PBMCs were then treated with PBS and different concentrations of sodium butyrate (Sigma), respectively, for 72 h in 24-well plates pre-coated with UV-irradiated E. coli at a PBMC:bacteria ratio of 1:10. After 72 h, the culture supernatant from the PBMCs was collected and stored at −80 °C for cytokine analysis. PBMCs were used for flow cytometry.
FCM (flow cytometry) analysis of Treg cells
Mononuclear cells were isolated from blood using Ficoll-Isopaue density gradient centrifugation (Ficoll-Paque, MP Biomedicals). FCM followed routine procedures, and cells were labeled with FITC anti-CD4 (eBioscience), APC anti-CD25 (eBioscience) and PE anti-Foxp3 (eBioscience).
Primary splenocyte culture
Untreated 7-week-old SD rats were sacrificed using cervical dislocation following ether exposure. The splenocytes were incubated with recombinant human TGF-β (2 ng/ml, Peprotech) and recombinant rat IL-6 (20 ng/ml, Peprotech) at 37 °C for 72 h, whereas the control was treated with vehicle. Experimental group cells were treated with PBS or different concentrations of sodium butyrate (Sigma) in addition to TGF-β and IL-6 .
Primary splenocyte and bone marrow-derived dendritic cell (BMDC) culture
Untreated 7-week-old SD rats were sacrificed using cervical dislocation following ether exposure. The splenocytes were incubated with recombinant human TGF-β (2 ng/ml, Peprotech) and recombinant rat IL-6 (20 ng/ml, Peprotech) at 37 °C for 72 h . Immature BMDCs were isolated using a protocol modified from Inaba et al. , in the presence of recombinant rat IL-4 (10 ng/ml, Peprotech) and recombinant rat granulocyte-macrophage colony-stimulating factor (GM-CSF, 10 ng/ml, Peprotech).
ELISA assay and western blotting
Cytokines (IL-10, IL-17A, IL-12 p70, TGF-β1, IL-6 and IL-23) were measured using a commercially available ELISA kit (Bender: IL-10, IL-17A, IL-12 p70 kits; SABC: IL-23 kit; eBioscience: TGF-β1, IL-6 kits) according to the manufacturer’s instructions. For western blotting, cells were lysed using 0.5 % NP40 lysis buffer and proteins were blotted following standard protocol. Antibodies to RORγt (Abcam) and actin (GenScript Corp) were purchased commercially.
Data was expressed as the mean ± standard error of the mean (SE). The data was analyzed with one-way ANOVA followed by a post hoc Duncan test (SPSS 17.0). P < 0.05 was considered significant.
Intestinal fatty acid levels
Body weight, colon histology and blood cytokine production
Treg analysis in rats
Th17 analysis of rats
Treg and Th17 cell differentiation in vitro
The major finding in this study was that butyrate exerted potent effects that ameliorated colitis lesions in a rat model by influencing Th cell differentiation and activation. This study proposes several possible mechanisms for these effects, including: 1) the inhibition of inflammatory Th17 cell activation and cytokine (IL-17) release, 2) the promotion of Treg cell differentiation and 3) alterations in the ratio in inflammatory cytokines (i.e., IL-10/IL-12) released by monocytes.
Firmicutes is a well-known butyrate-producing bacterium and several studies have confirmed that a reduction in F. prausnitzii and its product in IBD patients is inversely correlated with disease scores [22, 23]. Butyrate-producing microbiotic pharmabiotics have been shown to be effective in TNBS models and are destined for clinical trials . Consistent with previous research in colitis models, our study confirmed that UC patients had lower fecal butyrate concentrations than did the control group. Our study utilized butyrate concentrations recommended by Di Sabatino et al.  and found that oral administration of butyrate resulted in increased percentage of butyric acid, fecal concentration of butyric acid, and total SCFA. This resulted in improved health status, including increased weight gain, lower colonic inflammation, and lower Neurath scores in the butyrate group rats as compared to the colitis group. These results were further confirmed by cytokine testing.
Th17 cells are a unique proinflammatory Th cell subset identified by RORγt and IL-17. Since the discovery of Th17, a number of studies have suggested that the IL-23/Th17/IL-17 pathway plays an important role in nearly all major autoimmune syndromes including IBD . Studies have found that IL-17 levels are increased in both the colonic mucosa and serum of IBD patients, and IL-17 blocking therapy is being tested in patients with IBD [26, 27]. Serum concentration of total SCFAs in rodents is around 0.1 ~ 1 mM, among which only 10 % are butyrate [28, 29]. Therefore, the serum concentration of butyrate is estimated to be approximately 100 μM at most. Under physiological concentration of butyrate, we found that the high levels of RORγt and IL-17 caused by TNBS were both significantly reduced by butyrate treatment, suggesting their protective nature in the onset of colitis. IL-6 signaling is required for Th17 cell lineage commitment and its differentiation is enforced by TGF-β . IL-23 is an essential upstream regulator of Th17 cells that maintains Th17 activity and function, and immature bone marrow dendritic cells (BMDCs) can be activated by lipopolysaccharide (LPS) from E.coli to secrete IL-23 [3, 21]. Our study found that plasma levels of IL-23 and IL-6 were significantly increased by TNBS treatment and reduced by butyrate administration. This suggests that the IL-23/Th17/IL-17 pathway is an effective target for butyrate treatment in the setting of inflammatory colitis. Our in vitro experiments in rat splenocytes and BMDCs further confirmed this in vivo data. When splenocytes differentiated into Th17 cells in vitro, we demonstrated a similar cytokine release profile to that observed in colitis rats. Only a high dose of butyrate (80 μM) could suppress the secretion of IL-23 by BMDCs and the secretion of IL-17 by the splenocytes when co-cultured with BMDCs. Consistent with IL-17 levels from cultured splenocytes, RORγt levels in splenocytes also decreased following butyrate treatment. Taken together, this suggests that butyrate inhibits Th17 differentiation.
Regulatory T cells (Treg) also differentiate from Th cells in presence of TGF-β . Tregs maintain homeostasis by producing anti-inflammatory cytokines such as IL-10 and exert important negative regulation of Th17 cells. Impaired function of IL-10 and the IL-10 receptor are associated with aggressive IBD . The insufficiency of Tregs in germ-free mice can be restored via a high-fiber diet induced by butyrate in vivo. This is corroborated by in vitro studies demonstrating that microbes producing butyrate stimulate the differentiation of Tregs and exert anti-inflammatory activity in the intestinal mucosa of a mouse model [30, 31]. Consistent with previous results, our in vivo study demonstrated butyrate treatment increased both the percentage of Treg and the levels of IL-10, suggesting that the protective effect of butyrate on intestinal inflammation was correlated with the level of IL-10. TGF-β, together with IL-6, can stimulate native T cells to differentiate into Th17 cells . Yet without sufficient IL-6, TGF-β stimulates native T cells differentiation into Tregs . Increased levels of Tregs in rat peripheral blood cells were found in combination with increased plasma levels of TGF-β, whereas butyrate treatment decreased IL-6 levels. The in vitro experiments in human PBMCs further confirmed this in vivo data. A high dosage of butyrate (80 μM) could promote secretion of TGF-β by PBMCs and increased Treg frequencies in PBMCs.
In summary, a fine balance exists between Treg and Th17 cells in a healthy state. The same Th cell pool that generates Treg is also capable of producing Th17 cells, and this is coordinated by cytokines including IL-10, TGF-β and IL-6. Our results suggest that butyrate, a well-known metabolite, played a key role in regulating this Treg/Th17 balance and in turn yielded important insights for the treatment of IBD.
BMDC, bone marrow DC cells; CD, crohn disease; IBD, inflammatory bowel disease; IL, interleukin-23; LPS, lipopolysaccharide; PBMC, peripheral blood mononuclear cell; RORγt, retinoic orphan receptor γt; SCFA, short chain fatty acid; TGF-β, transforming growth factor β; Th17, helper T lymphocyte 17; TNBS, 2,4,6-trinitrobenzenesulfonic acid; UC, ulcerative colitis
The authors thank the advice provided by Ms Hongjing Yu and Mr Lichuan Guo. We thank Professor Liu for the technique assistance.
This study has been supported by a research grant from Beijing Renze Foundation (ZX-IBD-13002), the National Natural Science Foundation of China (No. 81170359), Nanjing Foundation for Development of Science and Technology (No.YKK15232) and the Outstanding Youth Project of Nanjing City (No.JQX14005).
Availability of data and materials
Clinical data will not be made available in order to protect the participants’ identity.
MZ designed the study; MZ and QZ did the cell and mice experiments; XH and HZ collected the fecal and tissue samples; HZ, TF and MZ per-formed the FACS and IHC analysis; MZ, XH and HZ drafted the manuscript and performed the rest ELISA experiment; RGD did the language editing; JZ and CY supervised and supported the study. All authors read and approved the final manuscript.
The authors declare that they have no competing interests.
Consent for publication
Ethics approval and consent to participate
All experiments utilizing animal and human samples were approved by the Ethical Committee of Medical Research, Nanjing Drum Tower Hospital, Affiliated Hospital of Nanjing University Medical School. Both patients and healthy participants were consented and signed the agreement to participate our study.
Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
- Dalal SR, Chang EB. The microbial basis of inflammatory bowel diseases. J Clin Invest. 2014;124(10):4190–6.View ArticlePubMedPubMed CentralGoogle Scholar
- Mangan PR, Harrington LE, O’Quinn DB, Helms WS, Bullard DC, Elson CO, Hatton RD, Wahl SM, Schoeb TR, Weaver CT. Transforming growth factor-beta induces development of the T(H)17 lineage. Nature. 2006;441(7090):231–4.View ArticlePubMedGoogle Scholar
- Yang JF, Sundrud MS, Skepner J, Yamagatal T. Targeting Th17 cells in autoimmune diseases. Trends Pharmacol Sci. 2014;35(10):493–500.View ArticlePubMedGoogle Scholar
- Gibson DJ, Ryan EJ, Doherty GA. Keeping the Bowel Regular: The Emerging Role of Treg as a Therapeutic Target in Inflammatory Bowel Disease. Inflamm Bowel Dis. 2013;19(12):2716–24.View ArticlePubMedGoogle Scholar
- Zheng Y, Rudensky AY. Foxp3 in control of the regulatory T cell lineage. Nat Immunol. 2007;8(5):457–62.View ArticlePubMedGoogle Scholar
- Glocker EO, Kotlarz D, Boztug K, Gertz EM, Schaffer AA, Noyan F, Perro M, Diestelhorst J, Allroth A, Murugan D, et al. Inflammatory Bowel Disease and Mutations Affecting the Interleukin-10 Receptor. New Engl J Med. 2009;361(21):2033–45.View ArticlePubMedPubMed CentralGoogle Scholar
- Fantini MC, Rio A, Fina D, Caruso R, Sarra M, Stolfi C, Becker C, Macdonald TT, Pallone F, Neurath MF, et al. Smad7 Controls Resistance of Colitogenic T Cells to Regulatory T Cell-Mediated Suppression. Gastroenterology. 2009;136(4):1308–16.View ArticlePubMedGoogle Scholar
- Bettelli E, Carrier YJ, Gao WD, Korn T, Strom TB, Oukka M, Weiner HL, Kuchroo VK. Reciprocal developmental pathways for the generation of pathogenic effector T(H)17 and regulatory T cells. Nature. 2006;441(7090):235–8.View ArticlePubMedGoogle Scholar
- Astbury SM, Corfe BM. Uptake and metabolism of the short-chain fatty acid butyrate, a critical review of the literature. Curr Drug Metab. 2012;13(6):815–21.View ArticlePubMedGoogle Scholar
- Berni Canani R, Di Costanzo M, Leone L. The epigenetic effects of butyrate: potential therapeutic implications for clinical practice. Clin Epigenetics. 2012;4(1):4.View ArticlePubMedPubMed CentralGoogle Scholar
- Hallert C, Bjorck I, Nyman M, Pousette A, Granno C, Svensson H. Increasing fecal butyrate in ulcerative colitis patients by diet: Controlled pilot study. Inflamm Bowel Dis. 2003;9(2):116–21.View ArticlePubMedGoogle Scholar
- Bennebroek Evertsz F, Nieuwkerk PT, Stokkers PC, Ponsioen CY, Bockting CL, Sanderman R, Sprangers MA. The patient simple clinical colitis activity index (P-SCCAI) can detect ulcerative colitis (UC) disease activity in remission: a comparison of the P-SCCAI with clinician-based SCCAI and biological markers. J Crohns Colitis. 2013;7(11):890–900.View ArticlePubMedGoogle Scholar
- Foligne B, Nutten S, Steidler L, Dennin V, Goudercourt D, Mercenier A, Pot B. Recommendations for improved use of the murine TNBS-induced colitis model in evaluating anti-inflammatory properties of lactic acid bacteria: Technical and microbiological aspects. Digest Dis Sci. 2006;51(2):390–400.View ArticlePubMedGoogle Scholar
- Neurath MF, Fuss I, Kelsall BL, Stuber E, Strober W. Antibodies to Interleukin-12 Abrogate Established Experimental Colitis in Mice. J Exp Med. 1995;182(5):1281–90.View ArticlePubMedGoogle Scholar
- Brown RS, Wahl RL. Overexpression of Glut-1 Glucose-Transporter in Human Breast-Cancer - an Immunohistochemical Study. Cancer. 1993;72(10):2979–85.View ArticlePubMedGoogle Scholar
- Foligne B, Nutten S, Grangette C, Dennin V, Goudercourt D, Poiret S, Dewulf J, Brassart D, Mercenier A, Pot B. Correlation between in vitro and in vivo immunomodulatory properties of lactic acid bacteria. World J Gastroentero. 2007;13(2):236–43.View ArticleGoogle Scholar
- Tanabe S, Kinuta Y, Saito Y. Bifidobacterium infantis suppresses proinflammatory interleukin-17 production in murine splenocytes and dextran sodium sulfate-induced intestinal inflammation. Int J Mol Med. 2008;22(2):181–5.PubMedGoogle Scholar
- Inaba K, Inaba M, Romani N, Aya H, Deguchi M, Ikehara S, Muramatsu S, Steinman RM. Generation of Large Numbers of Dendritic Cells from Mouse Bone-Marrow Cultures Supplemented with Granulocyte Macrophage Colony-Stimulating Factor. J Exp Med. 1992;176(6):1693–702.View ArticlePubMedGoogle Scholar
- Sokol H, Pigneur B, Watterlot L, Lakhdari O, Bermudez-Humaran LG, Gratadoux JJ, Blugeon S, Bridonneau C, Furet JP, Corthier G, et al. Faecalibacterium prausnitzii is an anti-inflammatory commensal bacterium identified by gut microbiota analysis of Crohn disease patients. P Natl Acad Sci USA. 2008;105(43):16731–6.View ArticleGoogle Scholar
- Schliesser U, Chopra M, Beilhack A, Appelt C, Vogel S, Schumann J, Panov I, Vogt K, Schlickeiser S, Olek S, et al. Generation of highly effective and stable murine alloreactive Treg cells by combined anti-CD4 mAb, TGF-beta, and RA treatment. Eur J Immunol. 2013;43(12):3291–305.View ArticlePubMedGoogle Scholar
- Loos M, Remaut E, Rottiers P, De Creus A. Genetically Engineered Lactococcus lactis Secreting Murine IL-10 Modulates the Functions of Bone Marrow-Derived Dendritic Cells in the Presence of LPS. Scand J Immunol. 2009;69(2):130–9.View ArticlePubMedGoogle Scholar
- Cao Y, Shen J, Ran ZH. Association between Faecalibacterium prausnitzii Reduction and Inflammatory Bowel Disease: A Meta-Analysis and Systematic Review of the Literature. Gastroent Res Pract. 2014.Google Scholar
- Machiels K, Joossens M, Sabino J, De Preter V, Arijs I, Eeckhaut V, Ballet V, Claes K, Van Immerseel F, Verbeke K, et al. A decrease of the butyrate-producing species Roseburia hominis and Faecalibacterium prausnitzii defines dysbiosis in patients with ulcerative colitis. Gut. 2014;63(8):1275–83.View ArticlePubMedGoogle Scholar
- Eeckhaut V, Ducatelle R, Sas B, Vermeire S, Van Immerseel F. Progress towards butyrate-producing pharmabiotics: Butyricicoccus pullicaecorum capsule and efficacy in TNBS models in comparison with therapeutics. Gut. 2014;63(2):367.View ArticlePubMedGoogle Scholar
- Di Sabatino A, Morera R, Ciccocioppo R, Cazzola P, Gotti S, Tinozzi FP, Tinozzi S, Corazza GR. Oral butyrate for mildly to moderately active Crohn’s disease. Aliment Pharm Ther. 2005;22(9):789–94.View ArticleGoogle Scholar
- Zhang M, Qiu X, Zhang H, Yang X, Hong N, Yang Y, Chen H, Yu C. Faecalibacterium prausnitzii inhibits interleukin-17 to ameliorate colorectal colitis in rats. PLoS One. 2014;9(10), e109146.View ArticlePubMedPubMed CentralGoogle Scholar
- Papp KA, Reid C, Foley P, Sinclair R, Salinger DH, Williams G, Dong H, Krueger JG, Russell CB, Martin DA. Anti-IL-17 receptor antibody AMG 827 leads to rapid clinical response in subjects with moderate to severe psoriasis: results from a phase I, randomized, placebo-controlled trial. J Invest Dermatol. 2012;132(10):2466–9.View ArticlePubMedGoogle Scholar
- Cummings JH, Hill MJ, Bone ES, Branch WJ, Jenkins DJ. The effect of meat protein and dietary fiber on colonic function and metabolism. II. Bacterial metabolites in feces and urine. Am J Clin Nutr. 1979;32(10):2094–101.PubMedGoogle Scholar
- Trompette A, Gollwitzer ES, Yadava K, Sichelstiel AK, Sprenger N, Ngom-Bru C, Blanchard C, Junt T, Nicod LP, Harris NL, et al. Gut microbiota metabolism of dietary fiber influences allergic airway disease and hematopoiesis. Nat Med. 2014;20(2):159–66.View ArticlePubMedGoogle Scholar
- Furusawa Y, Obata Y, Fukuda S, Endo TA, Nakato G, Takahashi D, Nakanishi Y, Uetake C, Kato K, Kato T, et al. Commensal microbe-derived butyrate induces the differentiation of colonic regulatory T cells. Nature. 2013;504(7480):446–50.View ArticlePubMedGoogle Scholar
- Arpaia N, Campbell C, Fan X, Dikiy S, van der Veeken J, de Roos P, Liu H, Cross JR, Pfeffer K, Coffer PJ, et al. Metabolites produced by commensal bacteria promote peripheral regulatory T-cell generation. Nature. 2013;504(7480):451–5.View ArticlePubMedPubMed CentralGoogle Scholar