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Cited by 236Gut microbiota and healthTryptophan and brain disordersAnimal Nutrition and Physiology

The DOI matches its Crossref record; 56 of the 56 references it cites were found in a registry or an index.

Tryptophan Dietary Impacts Gut Barrier and Metabolic Diseases

Open access
Taleb, Soraya·2019·Frontiers in Immunology
DOI 10.3389/fimmu.2019.02113PMC PMC6746884
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Abstract

The intestine has a major role in the digestion and absorption of nutrients, and gut barrier is the first defense line against harmful pathogens. Alteration of the intestinal barrier is associated with enhanced intestinal permeability and development of numerous pathological diseases including gastrointestinal and cardiometabolic diseases. Among the metabolites that play an important role within intestinal health, L Tryptophan (Trp) is one of the nine essential amino acids supplied by diet, whose metabolism appears as a key modulator of gut microbiota, with major impacts on physiological, and pathological pathways. Recently, emerging evidence showed that the Trp catabolism through one major enzyme indoleamine 2,3-dioxygenase 1 (IDO1) expressed by the host affects Trp metabolism by gut microbiota to generate indole metabolites, thereby altering gut function and health in mice and humans. In this mini review, I summarize the most recent advances concerning the role of Trp metabolism in host-microbiota cross-talk in health, and metabolic diseases. This novel aspect of IDO1 function in intestine will better explain its complex roles in a broad range of disease states where the gut function affects local as well as systemic health, and will open new therapeutic strategies.

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Crossref · 10.3389/fimmu.2019.02113

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Figure 1 Simplified illustration of the kynurenine pathway in the gastrointestinal tract. Tryptophan (Trp) is predominantly converted into kynurenine (Kyn) pathway (KP) by the indoleamine 2,3-dioxygenase 1 (IDO). A small amount of Trp is converted by gut microbiota through the action of the enzyme tryptophanase, into indole, and its derivatives and into tryptamine. Indole metabolites could be converted in the liver into indoxyl sulfate. Another fraction of Trp is converted through Trp hydroxylase 1 (TpH 1) into serotonin.
Figure 1 Simplified illustration of the kynurenine pathway in the gastrointestinal tract. Tryptophan (Trp) is predominantly converted into kynurenine (Kyn) pathway (KP) by the indoleamine 2,3-dioxygenase 1 (IDO). A small amount of Trp is converted by gut microbiota through the action of the enzyme tryptophanase, into indole, and its derivatives and into tryptamine. Indole metabolites could be converted in the liver into indoxyl sulfate. Another fraction of Trp is converted through Trp hydroxylase 1 (TpH 1) into serotonin.CC BY · PubMed Central
Figure 2 Potential mechanism of actions of Trp metabolites in the gastrointestinal tract. In homeostatic condition, Tryptophan (Trp) is used by the host indoleamine 2,3-dioxygenase (IDO) to be converted to Kynurenine (Kyn), and by gut microbiota to produce indole metabolites. Several indole derivatives have been described as activators of the AHR that promotes IL-22 production, which stimulates mucosal defense via the induction of antimicrobial proteins (AMP). In addition, indoles may affect mucosal homeostasis by stimulating mucin production and promoting epithelial barrier function by enhancing tight junction proteins. Also, indoles induce the release of the incretin, glucagon-like peptide 1 (GLP-1), in enteroendocrine L cells, which is known to stimulate insulin secretion, suppress appetite, and inhibit gastrointestinal motility, and secretion. In an inflammatory disease condition such as obesity, the increase in IDO activity leads to decreased indole production from Trp and thus low GLP-1 and IL-22 production leading to increased intestinal permeability and lipopolysaccharide (LPS) translocation in the systemic circulation, resulting in peripheral inflammation, liver steatosis, and insulin resistance.
Figure 2 Potential mechanism of actions of Trp metabolites in the gastrointestinal tract. In homeostatic condition, Tryptophan (Trp) is used by the host indoleamine 2,3-dioxygenase (IDO) to be converted to Kynurenine (Kyn), and by gut microbiota to produce indole metabolites. Several indole derivatives have been described as activators of the AHR that promotes IL-22 production, which stimulates mucosal defense via the induction of antimicrobial proteins (AMP). In addition, indoles may affect mucosal homeostasis by stimulating mucin production and promoting epithelial barrier function by enhancing tight junction proteins. Also, indoles induce the release of the incretin, glucagon-like peptide 1 (GLP-1), in enteroendocrine L cells, which is known to stimulate insulin secretion, suppress appetite, and inhibit gastrointestinal motility, and secretion. In an inflammatory disease condition such as obesity, the increase in IDO activity leads to decreased indole production from Trp and thus low GLP-1 and IL-22 production leading to increased intestinal permeability and lipopolysaccharide (LPS) translocation in the systemic circulation, resulting in peripheral inflammation, liver steatosis, and insulin resistance.CC BY · PubMed Central

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Metadata

Authors
Taleb, S.
Affiliations
Inserm (FR)
Corresponding author
Taleb, Soraya
ORCID
Taleb, Soraya
Venue
Frontiers in Immunology
Publisher
Frontiers Media SA
Published
2019-09-10
Volume
10
Pages
2113-2113
ISSN
1664-3224 (ISSN-L)
DOI
10.3389/fimmu.2019.02113
PMC
PMC6746884
OpenAlex
W2969960763
Cited by
236
References
56
Citations by year
2026: 20 · 2025: 55 · 2024: 28 · 2023: 43 · 2022: 32 · 2021: 34 · 2020: 21 · 2019: 1
FWCI
1.94
Type
journal article
Language
en
Open access
Licence
Locations
  • Frontiers in Immunology (publishedVersion, cc-by)
  • PubMed Central (publishedVersion, cc-by)
  • PubMed (publishedVersion)
  • DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion, cc-by-sa)
Funders
  • Institut National de la Santé et de la Recherche Médicale
  • Fondation pour la Recherche Médicale (DEQ20161136699)
  • Fondation de France
Topics
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Gut microbiota and health
  • Life Sciences › Neuroscience › Biological Psychiatry › Tryptophan and brain disorders
  • Life Sciences › Agricultural and Biological Sciences › Animal Science and Zoology › Animal Nutrition and Physiology
Keywords
tryptophan metabolism, IDO1, intestinal barrier, intestinal permeability, gut microbiota, indole metabolites, metabolic disorders, cardiometabolic disease, dietary amino acids
MeSH terms
Gastrointestinal Microbiome, Host Microbial Interactions, Animals, Diet, Humans, Intestinal Mucosa, Intestines, Metabolic Diseases, Tryptophan, Indoleamine-Pyrrole 2,3,-Dioxygenase, Mice, Microbiota

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