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Impact of the Gut Microbiota on Intestinal Immunity Mediated by Tryptophan Metabolism

Jing Gao, Kang Xu, Hongnan Liu and 5 more

Frontiers in Cellular and Infection Microbiology · 2018 · Review

doi:10.3389/fcimb.2018.00013

Abstract

The gut microbiota influences the health of the host, especially with regard to gut immune homeostasis and the intestinal immune response. In addition to serving as a nutrient enhancer, L-tryptophan (Trp) plays crucial roles in the balance between intestinal immune tolerance and gut microbiota maintenance. Recent discoveries have underscored that changes in the microbiota modulate the host immune system by modulating Trp metabolism. Moreover, Trp, endogenous Trp metabolites (kynurenines, serotonin, and melatonin), and bacterial Trp metabolites (indole, indolic acid, skatole, and tryptamine) have profound effects on gut microbial composition, microbial metabolism, the host's immune system, the host-microbiome interface, and host immune system-intestinal microbiota interactions. The aryl hydrocarbon receptor (AhR) mediates the regulation of intestinal immunity by Trp metabolites (as ligands of AhR), which is beneficial for immune homeostasis. Among Trp metabolites, AhR ligands consist of endogenous metabolites, including kynurenine, kynurenic acid, xanthurenic acid, and cinnabarinic acid, and bacterial metabolites, including indole, indole propionic acid, indole acetic acid, skatole, and tryptamine. Additional factors, such as aging, stress, probiotics, and diseases (spondyloarthritis, irritable bowel syndrome, inflammatory bowel disease, colorectal cancer), which are associated with variability in Trp metabolism, can influence Trp-microbiome-immune system interactions in the gut and also play roles in regulating gut immunity. This review clarifies how the gut microbiota regulates Trp metabolism and identifies the underlying molecular mechanisms of these interactions. Increased mechanistic insight into how the microbiota modulates the intestinal immune system through Trp metabolism may allow for the identification of innovative microbiota-based diagnostics, as well as appropriate nutritional supplementation of Trp to prevent or alleviate intestinal inflammation. Moreover, this review provides new insight regarding the influence of the gut microbiota on Trp metabolism. Additional comprehensive analyses of targeted Trp metabolites (including endogenous and bacterial metabolites) are essential for experimental preciseness, as the influence of the gut microbiota cannot be neglected, and may explain contradictory results in the literature.

References 214

  1. 1.

    Anders H. J. Andersen K. Stecher B. (2013 ). The intestinal microbiota, a leaky gut, and abnormal immunity in kidney disease. Kidney Int. 83, 1010–1016.

    Not in our library10.1038/ki.2012.440

  2. 2.

    Anderson G. Maes M. (2015 ). The gut–brain axis: the role of melatonin in linking psychiatric, inflammatory and neurodegenerative conditions. Adv. Integr. Med. 2, 31–37.

    Not in our library10.1016/j.aimed.2014.12.007

  3. 3.

    Anderson G. Seo M. Berk M. F. Carvalho A. Maes M. (2016 ). Gut permeability and microbiota in parkinson disease: role of depression, tryptophan catabolites, oxidative and nitrosative stress and melatonergic pathways. Curr. Pharm. Des. 22, 6142–6151.

    Not in our library10.2174/1381612822666160906161513

  4. 4.

    Arsenescu R. Arsenescu V. Zhong J. Nasser M. Melinte R. Dingle R. W. C.. (2011 ). Role of the xenobiotic receptor in inflammatory bowel disease. Inflamm. Bowel Dis. 17, 1149–1162.

    Not in our library10.1002/ibd.21463

  5. 5.
  6. 6.

    Bai M. Liu H. Xu K. Oso A. O. Wu X. Liu G.. (2017 ). A review of the immunomodulatory role of dietary tryptophan in livestock and poultry. Amino Acids 49, 67–74.

    Not in our library10.1007/s00726-016-2351-8

  7. 7.

    Bailey M. T. (2014 ). Influence of stressor-induced nervous system activation on the intestinal microbiota and the importance for immunomodulation. Adv. Exp. Med. Biol. 817, 255–276.

    Not in our library10.1007/978-1-4939-0897-4_12

  8. 8.

    Balsari A. Ceccarelli A. Dubini F. Fesce E. Poli G. (1982 ). The fecal microbial population in the irritable bowel syndrome. Microbiologica 5, 185–194.

    Not in our library

  9. 9.

    Bansal T. Alaniz R. C. Wood T. K. Jayaraman A. (2010 ). The bacterial signal indole increases epithelial-cell tight-junction resistance and attenuates indicators of inflammation. Proc. Natl. Acad. Sci. U.S.A. 107, 228–233.

    Not in our library10.1073/pnas.0906112107

  10. 10.

    Behnsen J. Jellbauer S. Wong C. P. Edwards R. A. George M. D. Ouyang W.. (2014 ). The cytokine IL-22 promotes pathogen colonization by suppressing related commensal bacteria. Immunity 40, 262–273.

    Not in our library10.1016/j.immuni.2014.01.003

  11. 11.

    Benson J. M. Shepherd D. M. (2011 ). Aryl hydrocarbon receptor activation by TCDD reduces inflammation associated with crohn's disease. Toxicol. Sci. 120, 68–78.

    Not in our library10.1093/toxsci/kfq360

  12. 12.

    Bessede A. Gargaro M. Pallotta M. T. Matino D. Servillo G. Brunacci C.. (2014 ). Aryl hydrocarbon receptor control of a disease tolerance defence pathway. Nature 511, 184–190.

    Not in our library10.1038/nature13323

  13. 13.

    Bhattarai Y. Muniz Pedrogo D. A. Kashyap P. C. (2017 ). Irritable bowel syndrome: a gut microbiota-related disorder? Am. J. Physiol. Gastrointest. Liver Physiol. 312, G52–G62.

    Not in our library10.1152/ajpgi.00338.2016

  14. 14.

    Biagi E. Candela M. Fairweather-Tait S. Franceschi C. Brigidi P. (2012 ). Aging of the human metaorganism: the microbial counterpart. Age 34, 247–267.

    Not in our library10.1007/s11357-011-9217-5

  15. 15.

    Biagi E. Candela M. Turroni S. Garagnani P. Franceschi C. Brigidi P. (2013 ). Ageing and gut microbes: perspectives for health maintenance and longevity. Pharmacol. Res. 69, 11–20.

    Not in our library10.1016/j.phrs.2012.10.005

  16. 16.

    Bischoff S. C. Mailer R. Pabst O. Weier G. Sedlik W. Li Z.. (2009 ). Role of serotonin in intestinal inflammation: knockout of serotonin reuptake transporter exacerbates 2,4,6-trinitrobenzene sulfonic acid colitis in mice. Am. J. Physiol. Gastrointest. Liver Physiol. 296, G685–G695.

    Not in our library10.1152/ajpgi.90685.2008

  17. 17.

    Bittinger M. A. Nguyen L. P. Bradfield C. A. (2003 ). Aspartate aminotransferase generates proagonists of the aryl hydrocarbon receptor. Mol. Pharmacol. 64, 550–556.

    Not in our library10.1124/mol.64.3.550

  18. 18.

    Blumberg R. Powrie F. (2012 ). Microbiota, disease, and back to health: a metastable journey. Sci. Transl. Med. 4:137rv137.

    Not in our library10.1126/scitranslmed.3004184

  19. 19.

    Bogdan C. (2001 ). Nitric oxide and the immune response. Nat. Immunol. 2:907.

    Not in our library10.1038/ni1001-907

  20. 20.

    Bouguen G. Dubuquoy L. Desreumaux P. Brunner T. Bertin B. (2015 ). Intestinal steroidogenesis. Steroids 103, 64–71.

    Not in our library10.1016/j.steroids.2014.12.022

  21. 21.

    Bubenik G. A. Brown G. M. Grota L. J. (1977 ). Immunohistological localization of melatonin in the rat digestive system. Experientia 33, 662–663.

    Not in our library10.1007/bf01946561

  22. 22.
  23. 23.

    Cerf-Bensussan N. Eberl G. (2012 ). The dialog between microbiota and the immune system: shaping the partners through development and evolution. Semin. Immunol. 24, 1–2.

    Not in our library10.1016/j.smim.2011.11.007

  24. 24.

    Cheng J. Palva A. M. De Vos W. M. Satokari R. (2013 ). Contribution of the intestinal microbiota to human health: from birth to 100 years of age. Curr. Top. Microbiol. Immunol. 358, 323–346.

    Not in our library10.1007/82_2011_189

  25. 25.

    Cheng Y. Jin U.-H. Allred C. D. Jayaraman A. Chapkin R. S. Safe S. (2015 ). Aryl hydrocarbon receptor activity of tryptophan metabolites in young adult mouse colonocytes. Drug Metab. Disposit. 43, 1536–1543.

    Not in our library10.1124/dmd.115.063677

  26. 26.
  27. 27.

    Chung K. T. Gadupudi G. S. (2011 ). Possible roles of excess tryptophan metabolites in cancer. Environ. Mol. Mutagen. 52, 81–104.

    Not in our library10.1002/em.20588

  28. 28.

    Ciorba M. A. Bettonville E. E. Mcdonald K. G. Metz R. Prendergast G. C. Newberry R. D.. (2010 ). Induction of IDO-1 by immunostimulatory DNA limits severity of experimental colitis. J. Immunol. 184, 3907–3916.

    Not in our library10.4049/jimmunol.0900291

  29. 29.

    Clarke G. Grenham S. Scully P. Fitzgerald P. Moloney R. D. Shanahan F.. (2013 ). The microbiome-gut-brain axis during early life regulates the hippocampal serotonergic system in a sex-dependent manner. Mol. Psychiatry 18, 666–673.

    Not in our library10.1038/mp.2012.77

  30. 30.

    Clarke G. Mckernan D. P. Gaszner G. Quigley E. M. Cryan J. F. Dinan T. G. (2012 ). A distinct profile of tryptophan metabolism along the kynurenine pathway downstream of toll-like receptor activation in irritable bowel syndrome. Front. Pharmacol. 3:90.

    Not in our library10.3389/fphar.2012.00090

  31. 31.

    Clarke G. O'mahony S. M. Hennessy A. A. Ross P. Stanton C. Cryan J. F.. (2009 ). Chain reactions: early-life stress alters the metabolic profile of plasma polyunsaturated fatty acids in adulthood. Behav. Brain Res. 205, 319–321.

    Not in our library10.1016/j.bbr.2009.07.008

  32. 32.

    Clarke G. Stilling R. M. Kennedy P. J. Stanton C. Cryan J. F. Dinan T. G. (2014 ). Minireview: gut microbiota: the neglected endocrine organ. Mol. Endocrinol. 28, 1221–1238.

    Not in our library10.1210/me.2014-1108

  33. 33.
  34. 34.

    Cook K. L. Rothrock M. J. Jr. Loughrin J. H. Doerner K. C. (2007 ). Characterization of skatole-producing microbial populations in enriched swine lagoon slurry. FEMS Microbiol. Ecol. 60, 329–340.

    Not in our library10.1111/j.1574-6941.2007.00299.x

  35. 35.

    Cooper H. S. Murthy S. Kido K. Yoshitake H. Flanigan A. (2000 ). Dysplasia and cancer in the dextran sulfate sodium mouse colitis model. Relevance to colitis-associated neoplasia in the human: a study of histopathology, B-catenin and p53 expression and the role of inflammation. Carcinogenesis 21, 757–768.

    Not in our library10.1093/carcin/21.4.757

  36. 36.

    Coste A. Dubuquoy L. Barnouin R. Annicotte J. S. Magnier B. Notti M.. (2007 ). LRH-1-mediated glucocorticoid synthesis in enterocytes protects against inflammatory bowel disease. Proc. Natl. Acad. Sci. U.S.A. 104, 13098–13103.

    Not in our library10.1073/pnas.0702440104

  37. 37.

    Costello M. E. Ciccia F. Willner D. Warrington N. Robinson P. C. Gardiner B.. (2014 ). Intestinal dysbiosis in ankylosing spondylitis. Arthritis Rheumatol. 67, 686–691.

    Not in our library10.1002/art.38967

  38. 38.

    Cox A. J. Pyne D. B. Saunders P. U. Fricker P. A. (2010 ). Oral administration of the probiotic Lactobacillus fermentum VRI-003 and mucosal immunity in endurance athletes. Br. J. Sports Med. 44, 222–226.

    Not in our library10.1136/bjsm.2007.044628

  39. 39.

    Dai X. Zhu B. T. (2010 ). Indoleamine 2,3-dioxygenase tissue distribution and cellular localization in mice: implications for its biological functions. J. Histochem. Cytochem. 58, 17–28.

    Not in our library10.1369/jhc.2009.953604

  40. 40.

    Davis R. E. (2014 ). Exploring the Effects of Gut-Derived Microbial Metabolites on Expression of SPI-1 Genes and Antimicrobial Resistance in Salmonella Typhimurium[D]. College Station, TX: Texas A&M University.

    Not in our library

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