. 2018 Jun 13;23(6):775-785.e5.

doi: 10.1016/j.chom.2018.05.004.

Gut Microbiota-Produced Tryptamine Activates an Epithelial G-Protein-Coupled Receptor to Increase Colonic Secretion

Affiliations

¹ Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN 55905, USA.
² Department of Bioengineering and ChEM-H, Stanford University, Stanford, CA 94305, USA.
³ Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94304, USA.
⁴ Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN 55905, USA.
⁵ Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN 55905, USA; Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN 55905, USA.
⁶ Department of Medicine, School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA; Greater Los Angeles Veterans Affairs Healthcare System, Los Angeles, CA 90073, USA; Brentwood Biomedical Research Institute, Los Angeles, CA 90073, USA.
⁷ Department of Pharmaceutics, University of Minnesota, Minneapolis, MN 55455, USA.
⁸ Department of Medicine, Division of Gastroenterology and Hepatology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
⁹ Department of Medicine, School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA; Greater Los Angeles Veterans Affairs Healthcare System, Los Angeles, CA 90073, USA; Brentwood Biomedical Research Institute, Los Angeles, CA 90073, USA; Department of Surgery, School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA.
¹⁰ Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN 55905, USA; Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN 55905, USA; Division of Gastroenterology and Hepatology, Mayo Clinic, Jacksonville, FL 32224, USA.
¹¹ Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN 55905, USA; Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN 55905, USA. Electronic address: [email protected].

PMID: 29902441
PMCID: PMC6055526
DOI: 10.1016/j.chom.2018.05.004

Gut Microbiota-Produced Tryptamine Activates an Epithelial G-Protein-Coupled Receptor to Increase Colonic Secretion

Yogesh Bhattarai et al. Cell Host Microbe. 2018.

. 2018 Jun 13;23(6):775-785.e5.

doi: 10.1016/j.chom.2018.05.004.

Authors

Affiliations

¹ Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN 55905, USA.
² Department of Bioengineering and ChEM-H, Stanford University, Stanford, CA 94305, USA.
³ Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94304, USA.
⁴ Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN 55905, USA.
⁵ Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN 55905, USA; Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN 55905, USA.
⁶ Department of Medicine, School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA; Greater Los Angeles Veterans Affairs Healthcare System, Los Angeles, CA 90073, USA; Brentwood Biomedical Research Institute, Los Angeles, CA 90073, USA.
⁷ Department of Pharmaceutics, University of Minnesota, Minneapolis, MN 55455, USA.
⁸ Department of Medicine, Division of Gastroenterology and Hepatology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
⁹ Department of Medicine, School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA; Greater Los Angeles Veterans Affairs Healthcare System, Los Angeles, CA 90073, USA; Brentwood Biomedical Research Institute, Los Angeles, CA 90073, USA; Department of Surgery, School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA.
¹⁰ Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN 55905, USA; Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN 55905, USA; Division of Gastroenterology and Hepatology, Mayo Clinic, Jacksonville, FL 32224, USA.
¹¹ Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN 55905, USA; Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN 55905, USA. Electronic address: [email protected].

PMID: 29902441
PMCID: PMC6055526
DOI: 10.1016/j.chom.2018.05.004

Abstract

Tryptamine, a tryptophan-derived monoamine similar to 5-hydroxytryptamine (5-HT), is produced by gut bacteria and is abundant in human and rodent feces. However, the physiologic effect of tryptamine in the gastrointestinal (GI) tract remains unknown. Here, we show that the biological effects of tryptamine are mediated through the 5-HT₄ receptor (5-HT₄R), a G-protein-coupled receptor (GPCR) uniquely expressed in the colonic epithelium. Tryptamine increases both ionic flux across the colonic epithelium and fluid secretion in colonoids from germ-free (GF) and humanized (ex-GF colonized with human stool) mice, consistent with increased intestinal secretion. The secretory effect of tryptamine is dependent on 5-HT₄R activation and is blocked by 5-HT₄R antagonist and absent in 5-HT₄R^-/- mice. GF mice colonized by Bacteroides thetaiotaomicron engineered to produce tryptamine exhibit accelerated GI transit. Our study demonstrates an aspect of host physiology under control of a bacterial metabolite that can be exploited as a therapeutic modality. VIDEO ABSTRACT.

Keywords: Bacteroides thetaiotaomicron; GI transit; IBS; constipation; genetically engineered; microbiome; motility; phage promoter; secretion; tryptophan.

PubMed Disclaimer

Conflict of interest statement

Declaration of Interests

The authors have no financial interests to declare. We have a patent (US20170042860A1) related to this work- “Methods and materials for using Ruminococcus gnavus or Clostridium sporogenes to treat gastrointestinal disorders.”

Figures

**Figure 1**
Tryptamine increases *Isc in vitro* in mice irrespective of sex and microbial colonization. Δ*Isc* in response to apically and basolaterally applied concentrations (30μM and 3mM) of tryptamine respectively in GF male (A, B) and GF female mice (C, D). Δ*Isc* in response to apically and basolaterally applied concentrations (30μM and 3mM) of tryptamine respectively in HM male (E, F) and HM female mice (G, H). Δ*Isc* in response to apically and basolaterally applied concentrations (30μM and 3mM) of tryptamine respectively in CR male (I, J) and CR female mice (K, L). n=4–6, paired *t-test*, ^*P < 0.05.

**Figure 2**
Tryptamine evoked Δ*Isc* is blocked by 5-HT₄R antagonist irrespective of sex and microbial colonization. Δ*Isc* in response to tryptamine applied apically (3mM, paired *t-test*) and cumulative concentrations of tryptamine applied basolaterally (*two-way ANOVA*) respectively either alone or in the presence of 5-HT₄R antagonist, GR-113808 (30nM) in GF male (A, B) and GF female mice (C, D). Δ*Isc* in response to tryptamine applied apically (3mM, paired *t-test*) and cumulative concentrations of tryptamine applied basolaterally (*two-way ANOVA*) respectively either alone or in the presence of 5-HT₄R antagonist, GR-113808 (30nM) in HM male (E, F) and HM female mice (G, H). Δ*Isc* in response to tryptamine applied apically (3mM, paired *t-test*) and cumulative concentrations of tryptamine applied basolaterally (two-way *ANOVA*) respectively either alone or in the presence of 5-HT₄R antagonist, GR-113808 (30nM) in CR male (I, J) and CR female mice (K, L). n=5–6, ^*P < 0.05.

**Figure 3**
Tryptamine evoked increase in *Isc* is absent in 5-HT₄R^−/− mice. Δ*Isc* in response to tryptamine applied apically (3mM, paired *t-test*) and cumulative concentrations of tryptamine applied basolaterally (*two-way ANOVA*) respectively in WT and in 5-HT₄R^−/− male (A, B) and female mice (C, D). n=5, ^*P < 0.05.

**Figure 4**
Tryptamine-evoked increase in *Isc* can be mediated by epithelial 5-HT₄R. Δ*Isc* in response to application cumulative concentration of tryptamine basolaterally (A, two-way *ANOVA*) and maximum Δ*Isc* (Imax) following application of tryptamine basolaterally (B, one-way *ANOVA*) either alone, or in presence of TTX (500nM) or in presence of TTX (500nM) and GR-113808 (30nM) in GF mice. n=4–5, ^*P < 0.05

**Figure 5**
Tryptamine increases fluid secretion in colonoids. Representative example of Calcein-AM –labeled colonoids before and after application of tryptamine (1mM) for thirty minutes in GF (A) and HM (B) colonoids. Arrows represent colonoids that show prominent change in area. Change in surface area is measured relative to vehicle at t = 0 (Baseline; 100%). Change in surface area normalized to baseline (t=0) after application of vehicle (medium alone), media with tryptamine (1mM), media with tryptamine (1mM) co-applied with GR-113808 (100 nM), and media with forskolin (10 μM) in colonoids from GF male (C) and HM male (D) mice for thirty minutes from three independent wells. n=5, one-way *ANOVA*, ^*P < 0.05

**Figure 6**
Tryptamine increases cAMP in colonoids irrespective of microbial colonization. Total cAMP (normalized to forskolin response) in colonoids from GF and HM male mice after incubation for an hour with either control media alone, media with tryptamine (1mM) and media with tryptamine (1mM) thirty minutes after pre-treatment with GR-113808 (100 nM). n=3, ^*P < 0.05, one-way *ANOVA.* See also Figure S5.

**Figure 7**
Colonization of GF mice with engineered *B. thetaiotaomicron* Trp D⁺ increases luminal conversion of tryptophan to tryptamine, without increasing circulating tryptamine and accelerates whole gut transit. Change in fecal (A–C) and serum (D–F) tryptophan, tryptamine and 5-HT concentrations following colonization of GF mice with either engineered *B. thetaiotaomicron* Trp D⁺ or *B. thetaiotaomicron* Trp D⁻ empty vector control. Change in normalized pellet water content (G) and whole gut transit (H) in GF male mice colonized with *B. thetaiotaomicron* Trp D⁺ or Trp D⁻. Mean ± SEM, n=5, un-paired *t-test* and one-way *ANOVA*, *P < 0.05. See also Figure S7.

See this image and copyright information in PMC

Comment in

A Microbial Drugstore for Motility.
Cryan JF, Clarke G, Dinan TG, Schellekens H. Cryan JF, et al. Cell Host Microbe. 2018 Jun 13;23(6):691-692. doi: 10.1016/j.chom.2018.05.020. Cell Host Microbe. 2018. PMID: 29902430

References

1. Anderson GM. Quantitation of tryptophan metabolites in rat feces by thin-layer chromatography. J Chromatogr. 1975;105(2):323–8. - PubMed
1. Anitha M, Reichardt F, Tabatabavakili S, Nezami BG, Chassaing B, Mwangi S, Vijay-Kumar M, Gewirtz A, Srinivasan S. Intestinal dysbiosis contributes to the delayed gastrointestinal transit in high-fat diet fed mice. Cell Mol Gastroenterol Hepatol. 2016;2(3):328–339. - PMC - PubMed
1. Ao M, Sarathy J, Domingue J, Alrefai WA, Rao MC. Chenodeoxycholic acid stimulates Cl(−) secretion via cAMP signaling and increases cystic fibrosis transmembrane conductance regulator phosphorylation in T84 cells. Am J Physiol Cell Physiol. 2013;305(4):C447–56. - PMC - PubMed
1. Bender DA. Biochemistry of tryptophan in health and disease. Mol Aspects Med. 1983;6(2):101–97. - PubMed
1. Bhattarai Y, Kashyap PC. Germ-Free Mice Model for Studying Host-Microbial Interactions. Methods Mol Biol. 2016;1438:123–35. - PubMed

Publication types

Actions
Actions
Actions

MeSH terms

Actions
Actions
Actions
Actions
Actions
Actions
Actions
Actions
Actions
Actions
Actions
Actions
Actions
Actions
Actions
Actions
Actions
Actions
Actions

Substances

Actions
Actions
Actions

Grants and funding

LinkOut - more resources

Full Text Sources
Other Literature Sources
- The Lens - Patent Citations Database
- scite Smart Citations
Molecular Biology Databases
- BacDive
- Mouse Genome Informatics (MGI)

Save citation to file

Email citation

Add to Collections

Add to My Bibliography

Your saved search

Create a file for external citation management software

Your RSS Feed

Gut Microbiota-Produced Tryptamine Activates an Epithelial G-Protein-Coupled Receptor to Increase Colonic Secretion

Affiliations

Gut Microbiota-Produced Tryptamine Activates an Epithelial G-Protein-Coupled Receptor to Increase Colonic Secretion

Authors

Affiliations

Abstract

Conflict of interest statement

Figures

Comment in

References

Publication types

MeSH terms

Substances

Grants and funding

LinkOut - more resources

Full Text Sources

Other Literature Sources

Molecular Biology Databases