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. 2015 Apr 9;161(2):264-76.
doi: 10.1016/j.cell.2015.02.047.

Indigenous bacteria from the gut microbiota regulate host serotonin biosynthesis

Jessica M Yano  1 , Kristie Yu  1 , Gregory P Donaldson  1 , Gauri G Shastri  1 , Phoebe Ann  1 , Liang Ma  2 , Cathryn R Nagler  3 , Rustem F Ismagilov  2 , Sarkis K Mazmanian  1 , Elaine Y Hsiao  4
Affiliations

Indigenous bacteria from the gut microbiota regulate host serotonin biosynthesis

Jessica M Yano et al. Cell. .

Erratum in

  • Cell. 2015 Sep 24;163:258

Abstract

The gastrointestinal (GI) tract contains much of the body's serotonin (5-hydroxytryptamine, 5-HT), but mechanisms controlling the metabolism of gut-derived 5-HT remain unclear. Here, we demonstrate that the microbiota plays a critical role in regulating host 5-HT. Indigenous spore-forming bacteria (Sp) from the mouse and human microbiota promote 5-HT biosynthesis from colonic enterochromaffin cells (ECs), which supply 5-HT to the mucosa, lumen, and circulating platelets. Importantly, microbiota-dependent effects on gut 5-HT significantly impact host physiology, modulating GI motility and platelet function. We identify select fecal metabolites that are increased by Sp and that elevate 5-HT in chromaffin cell cultures, suggesting direct metabolic signaling of gut microbes to ECs. Furthermore, elevating luminal concentrations of particular microbial metabolites increases colonic and blood 5-HT in germ-free mice. Altogether, these findings demonstrate that Sp are important modulators of host 5-HT and further highlight a key role for host-microbiota interactions in regulating fundamental 5-HT-related biological processes.

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Figures

Figure 1
Figure 1. The Gut Microbiota Modulates Host Peripheral Serotonin Levels
(A) Levels of serum 5-HT. Data are normalized to serum 5-HT in SPF mice. n=8–13. (B) Levels of colon 5-HT relative to total protein. Data are normalized to colon 5-HT relative to total protein in SPF mice. n=8–13. (C) Colonic expression of TPH1 relative to GAPDH. Data are normalized to expression levels in SPF mice. n=4. (D) Colonic expression of SLC6A4 relative to GAPDH. Data are normalized to expression levels in SPF mice. n=4. Data are presented as mean ± SEM. *p < 0.05, **p < 0.01, ***p < 0.001, n.s.=not statistically significant. SPF=specific pathogen-free (conventionally-colonized), GF=germ-free, CONV.=SPF conventionalized, ABX=antibiotic-treated, VEH=vehicle (water)-treated. See also Figure S1.
Figure 2
Figure 2. Indigenous Spore-forming Bacteria Increase 5-HT Levels in Colon Enterochromaffin Cells
(A) Representative images of colons stained for chromagranin A (CgA) (left), 5-HT (center) and merged (right). Arrows indicate CgA-positive cells that lack 5-HT staining. n=3–7 mice/group. (B) Quantitation of 5-HT+ cell number per area of colonic epithelial tissue. n=3–7 mice/group. (C) Quantitation of CgA+ cell number per area of colonic epithelial tissue. n=3–7 mice/group. (D) Ratio of 5-HT+ cells/CgA+ cells per area of colonic epithelial tissue. n=3–7 mice/group. Data are presented as mean ± SEM. *p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001. SPF=specific pathogen-free (conventionally-colonized), GF=germ-free, CONV.=SPF conventionalized, ABX=antibiotic-treated, Sp=spore-forming bacteria, PCPA=para-chlorophenylalanine. See also Figure S2.
Figure 3
Figure 3. Indigenous Spore-forming Bacteria Induce Colon 5-HT Biosynthesis and Systemic 5-HT Bioavailability
(A) Levels of serum 5-HT. Data are normalized to serum 5-HT levels in SPF mice. SPF, n=13; GF, n=17; GF+conv.=P21 conventionalization, n=4; SPF+Abx= P42 antibiotic treatment, n=7; B. fragilis monoassociation (BF), n=6; SFB=Segmented Filamentous Bacteria monoassociation, n=4; ASF=Altered Schaedler Flora P21 colonization, n=4; Sp=spore-forming bacteria, P21 colonization, n=4; B. uniformis P21 colonization, n=4; Bd=Bacteroides consortium, n=3. (B) Levels of colon 5-HT relative to total protein. Data are normalized to colon 5-HT relative to total protein in SPF mice. n=5–15. (C) Levels of colon 5-HT relative to total protein after intrarectal treatment with the Tph inhibitor, PCPA, or vehicle. n=4. (D) Colonic expression of TPH1 relative to GAPDH. Data are normalized to expression levels in SPF mice. n=3. Data are presented as mean ± SEM. *p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001, n.s.=not statistically significant. SPF=specific pathogen-free (conventionally-colonized), GF=germ-free, Sp=spore-forming bacteria, PCPA=para-chlorophenylalanine. See also Figure S3.
Figure 4
Figure 4. Microbiota-Mediated Regulation of Host Serotonin Modulates Gastrointestinal Motility
(A) Total time for transit of orally administered carmine red solution through the GI tract. n=4–8. (B) Defecation rate as measured by number of fecal pellets produced relative to total transit time. n=4–8. (C) Representative images of c-fos and 5HT4 colocalization in the colonic submucosa and muscularis externa. n=4–5 mice/group. (D) Quantitation of total c-fos fluorescence intensity in the colonic submucosa and muscularis externa. n=4–5 mice/group. (E) Quantitation of total 5HT4 fluorescence intensity in the colonic submucosa and muscularis externa. n=4–5 mice/group. (F) Quantitation and representative images of c-fos and calb2 (calretinin) colocalization in the colonic submucosa and muscularis externa. n=5–8 mice/group. Data are presented as mean ± SEM. *p
Figure 5
Figure 5. Microbiota-Mediated Regulation of Host Serotonin Modulates Hemostasis
(A) Time to cessation of bleeding in response to tail injury. n=7–16. (B) Platelet activation, as measured by percentage of large, high granularity (FSChigh, SSChigh) events after collagen stimulation relative to unstimulated controls. n=3. (C) Representative flow cytometry plots of large, high granularity (FSChigh, SSChigh) activated platelets after collagen stimulation (bottom), as compared to unstimulated controls (top). n=3. (D)–(E) Geometric mean fluorescence intensity of granulophysin (CD63; D), P-selectin (E), JON/A (integrin αIIbβ3; F) expression in collagen-stimulated platelets (left). Representative histograms (right) of event count vs. fluorescence intensity (log scale) for platelets treated with collagen (red line) or vehicle (blue line). n=3. Data for platelet assays are representative of three independent trials with at least three mice in each group. Data are presented as mean ± SEM. *p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001, n.s.=not statistically significant. SPF=specific pathogen-free (conventionally-colonized), GF=germ-free, Sp=spore-forming bacteria, PCPA=para-chlorophenylalanine. See also Figure S5.
Figure 6
Figure 6. Microbial Metabolites Mediate Effects of the Microbiota on Host Serotonin
(A) Levels of 5-HT released from RIN14B cells after exposure to colonic luminal filtrate from SPF, GF and Sp-colonized mice, or to ionomycin (iono). Data are normalized to 5-HT levels in vehicle-treated controls (hatched gray line at 1). Asterisks directly above bars indicate significance compared to controls; asterisks at the top of the graph denote significance between experimental groups. n=3. (B) Expression of TPH1 relative to GAPDH in RIN14B cells after exposure to colon luminal filtrate from SPF, GF and Sp-colonized mice, or to ionomycin (iono). Data are normalized to gene expression in vehicle-treated controls (hatched gray line at 1). Asterisks directly above bars indicate significance compared to controls, whereas asterisks at the top of the graph denote significance between experimental groups. n=4. (C) Principal components analysis of the fecal metabolome from GF mice colonized with SPF, ASF, Sp, or hSp. n=6. (D) Levels of 5-HT released from RIN14B cells after exposure to metabolites: acetate (1 mM), α-tocopherol (8 uM), arabinose (50 uM), azelate (50 uM), butyrate (100 uM), cholate (75 uM), deoxycholate (25 uM), ferulate (25 uM), GABA (25 uM), glycine (50 uM), N-methyl proline (0.5 uM), oleanolate (50 uM), p-aminobenzoate (1 uM), propionate (100 uM), taurine (50 uM), tyramine (100 uM). Data are normalized to 5-HT levels in vehicle-treated controls (gray line at 1). n=5–19. (E) Expression of TPH1 relative to GAPDH in RIN14B cells after metabolite exposure. Data are normalized to expression in vehicle-treated controls (gray line at 1). n=3–4. (F) Levels of 5-HT in colons (left) and serum (center) of GF mice at 30 min after intrarectal injection of deoxycholate (125 mg/kg) or vehicle. Expression of TPH1 relative to GAPDH (right) at 1 hr post injection. n=3–8. (G) Phylogenetic tree displaying key Sp. (M) and hSp. (H) operational taxonomic units (OTUs) relative to reference Clostridium species with reported 7α-dehydroxylation activity (red circles). Relative abundances are indicated in parentheses. n=3. Data are presented as mean ± SEM. *p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001, n.s.=not statistically significant. SPF=specific pathogen-free (conventionally-colonized), GF=germ-free, Sp=spore-forming bacteria, iono=15uM ionomycin, ASF=Altered Schaedler Flora, hSp=humanderived spore-forming bacteria. See also Figures S6 and S7.
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References

    1. Alemi F, Poole DP, Chiu J, Schoonjans K, Cattaruzza F, Grider JR, Bunnett NW, Corvera CU. The receptor TGR5 mediates the prokinetic actions of intestinal bile acids and is required for normal defecation in mice. Gastroenterology. 2013;144:145–154. - PMC - PubMed
    1. Amireault P, Sibon D, Cote F. Life without peripheral serotonin: insights from tryptophan hydroxylase 1 knockout mice reveal the existence of paracrine/autocrine serotonergic networks. ACS chemical neuroscience. 2013;4:64–71. - PMC - PubMed
    1. Appleby RN, Walters JR. The role of bile acids in functional GI disorders. Neurogastroenterology and motility : the official journal of the European Gastrointestinal Motility Society. 2014;26:1057–1069. - PubMed
    1. Atarashi K, Tanoue T, Oshima K, Suda W, Nagano Y, Nishikawa H, Fukuda S, Saito T, Narushima S, Hase K, et al. Treg induction by a rationally selected mixture of Clostridia strains from the human microbiota. Nature. 2013;500:232–236. - PubMed
    1. Baganz NL, Blakely RD. A dialogue between the immune system and brain, spoken in the language of serotonin. ACS chemical neuroscience. 2013;4:48–63. - PMC - PubMed

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