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Escherichia coli Nissle 1917 enhances bioavailability of serotonin in gut tissues through modulation of synthesis and clearance.

Nzakizwanayo J, Dedi C, Standen G, Macfarlane WM, Patel BA, Jones BV - Sci Rep (2015)

Bottom Line: Exposure of tissue to EcN cells, but not MG1655 cells, was found to increase levels of extra-cellular 5-HT.These effects were not observed when tissues were treated with cell-free supernatant from bacterial cultures.Measurement of 5-HT precursors and metabolites indicated EcN also increases intracellular 5-HTP and reduces 5-HIAA.

View Article: PubMed Central - PubMed

Affiliation: School of Pharmacy and Biomolecular Sciences, University of Brighton, Brighton, BN2 4GJ, United Kingdom.

ABSTRACT
Accumulating evidence shows indigenous gut microbes can interact with the human host through modulation of serotonin (5-HT) signaling. Here we investigate the impact of the probiotic Escherichia coli Nissle 1917 (EcN) on 5-HT signalling in gut tissues. Ex-vivo mouse ileal tissue sections were treated with either EcN or the human gut commensal MG1655, and effects on levels of 5-HT, precursors, and metabolites, were evaluated using amperometry and high performance liquid chromatography with electrochemical detection (HPLC-EC). Exposure of tissue to EcN cells, but not MG1655 cells, was found to increase levels of extra-cellular 5-HT. These effects were not observed when tissues were treated with cell-free supernatant from bacterial cultures. In contrast, when supernatant recovered from untreated ileal tissue was pre-incubated with EcN, the derivative cell-free supernatant was able to elevate 5-HT overflow when used to treat fresh ileal tissue. Measurement of 5-HT precursors and metabolites indicated EcN also increases intracellular 5-HTP and reduces 5-HIAA. The former pointed to modulation of tryptophan hydroxylase-1 to enhance 5-HT synthesis, while the latter indicates an impact on clearance into enterocytes through SERT. Taken together, these findings show EcN is able to enhance 5-HT bioavailability in ileal tissues through interaction with compounds secreted from host tissues.

No MeSH data available.


Related in: MedlinePlus

Measurement of extracellular 5-HT in ileal tissues treated with E. coli Nissle 1917 and MG1655.Ileal tissue samples and E. coli cultures were co-incubated for 1 h at 37 °C, 5% CO2, and extra cellular 5-HT levels measured in real-time using electrochemical methods (amperometry). (A) Example of electrochemical measurements obtained during experiments and converted to uM 5-HT based on standard curves constructed from known 5-HT concentrations. The BDD electrode was placed 0.1 mm over tissue. (B) Measurements of extracellular 5-HT from treated and untreated tissue sections. In all cases levels are normalized to surface area of the tissue. Data shown as mean ± S.E.M. (n = 4). (C) Example images of treated or untreated tissue sections used in experiments demonstrating intact epithelium following treatment and measurements. Arrows indicated the BDD electrode, and all images are ×10 magnification. KB - control samples incubated with Krebs buffer only; +EcN- samples treated with E. coli Nissle 1917; +MG1655 - samples treated with E. coli MG1655. ***p ≤ 0.001 vs KB; ††††p ≤ 0.0001 vs MG1655.
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f1: Measurement of extracellular 5-HT in ileal tissues treated with E. coli Nissle 1917 and MG1655.Ileal tissue samples and E. coli cultures were co-incubated for 1 h at 37 °C, 5% CO2, and extra cellular 5-HT levels measured in real-time using electrochemical methods (amperometry). (A) Example of electrochemical measurements obtained during experiments and converted to uM 5-HT based on standard curves constructed from known 5-HT concentrations. The BDD electrode was placed 0.1 mm over tissue. (B) Measurements of extracellular 5-HT from treated and untreated tissue sections. In all cases levels are normalized to surface area of the tissue. Data shown as mean ± S.E.M. (n = 4). (C) Example images of treated or untreated tissue sections used in experiments demonstrating intact epithelium following treatment and measurements. Arrows indicated the BDD electrode, and all images are ×10 magnification. KB - control samples incubated with Krebs buffer only; +EcN- samples treated with E. coli Nissle 1917; +MG1655 - samples treated with E. coli MG1655. ***p ≤ 0.001 vs KB; ††††p ≤ 0.0001 vs MG1655.

Mentions: In order to assess the effect of EcN on 5-HT overflow from EC cells we first treated ex-vivo ileal tissue with cultures of EcN, or the gastrointestinal commensal E. coli MG1655 as a control, and measured extra-cellular levels of 5-HT post treatment. In tissues treated with EcN we observed a significant elevation in extra-cellular levels of 5-HT, compared to untreated controls or MG1655 treated tissues (Fig. 1a,b). Microscopic examination of tissue treated with E. coli cultures confirmed that tissue remained intact and the observed elevation in 5-HT levels induced by EcN was not due to the disruption or degradation of the intestinal epithelium (Fig. 1c).


Escherichia coli Nissle 1917 enhances bioavailability of serotonin in gut tissues through modulation of synthesis and clearance.

Nzakizwanayo J, Dedi C, Standen G, Macfarlane WM, Patel BA, Jones BV - Sci Rep (2015)

Measurement of extracellular 5-HT in ileal tissues treated with E. coli Nissle 1917 and MG1655.Ileal tissue samples and E. coli cultures were co-incubated for 1 h at 37 °C, 5% CO2, and extra cellular 5-HT levels measured in real-time using electrochemical methods (amperometry). (A) Example of electrochemical measurements obtained during experiments and converted to uM 5-HT based on standard curves constructed from known 5-HT concentrations. The BDD electrode was placed 0.1 mm over tissue. (B) Measurements of extracellular 5-HT from treated and untreated tissue sections. In all cases levels are normalized to surface area of the tissue. Data shown as mean ± S.E.M. (n = 4). (C) Example images of treated or untreated tissue sections used in experiments demonstrating intact epithelium following treatment and measurements. Arrows indicated the BDD electrode, and all images are ×10 magnification. KB - control samples incubated with Krebs buffer only; +EcN- samples treated with E. coli Nissle 1917; +MG1655 - samples treated with E. coli MG1655. ***p ≤ 0.001 vs KB; ††††p ≤ 0.0001 vs MG1655.
© Copyright Policy - open-access
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4663480&req=5

f1: Measurement of extracellular 5-HT in ileal tissues treated with E. coli Nissle 1917 and MG1655.Ileal tissue samples and E. coli cultures were co-incubated for 1 h at 37 °C, 5% CO2, and extra cellular 5-HT levels measured in real-time using electrochemical methods (amperometry). (A) Example of electrochemical measurements obtained during experiments and converted to uM 5-HT based on standard curves constructed from known 5-HT concentrations. The BDD electrode was placed 0.1 mm over tissue. (B) Measurements of extracellular 5-HT from treated and untreated tissue sections. In all cases levels are normalized to surface area of the tissue. Data shown as mean ± S.E.M. (n = 4). (C) Example images of treated or untreated tissue sections used in experiments demonstrating intact epithelium following treatment and measurements. Arrows indicated the BDD electrode, and all images are ×10 magnification. KB - control samples incubated with Krebs buffer only; +EcN- samples treated with E. coli Nissle 1917; +MG1655 - samples treated with E. coli MG1655. ***p ≤ 0.001 vs KB; ††††p ≤ 0.0001 vs MG1655.
Mentions: In order to assess the effect of EcN on 5-HT overflow from EC cells we first treated ex-vivo ileal tissue with cultures of EcN, or the gastrointestinal commensal E. coli MG1655 as a control, and measured extra-cellular levels of 5-HT post treatment. In tissues treated with EcN we observed a significant elevation in extra-cellular levels of 5-HT, compared to untreated controls or MG1655 treated tissues (Fig. 1a,b). Microscopic examination of tissue treated with E. coli cultures confirmed that tissue remained intact and the observed elevation in 5-HT levels induced by EcN was not due to the disruption or degradation of the intestinal epithelium (Fig. 1c).

Bottom Line: Exposure of tissue to EcN cells, but not MG1655 cells, was found to increase levels of extra-cellular 5-HT.These effects were not observed when tissues were treated with cell-free supernatant from bacterial cultures.Measurement of 5-HT precursors and metabolites indicated EcN also increases intracellular 5-HTP and reduces 5-HIAA.

View Article: PubMed Central - PubMed

Affiliation: School of Pharmacy and Biomolecular Sciences, University of Brighton, Brighton, BN2 4GJ, United Kingdom.

ABSTRACT
Accumulating evidence shows indigenous gut microbes can interact with the human host through modulation of serotonin (5-HT) signaling. Here we investigate the impact of the probiotic Escherichia coli Nissle 1917 (EcN) on 5-HT signalling in gut tissues. Ex-vivo mouse ileal tissue sections were treated with either EcN or the human gut commensal MG1655, and effects on levels of 5-HT, precursors, and metabolites, were evaluated using amperometry and high performance liquid chromatography with electrochemical detection (HPLC-EC). Exposure of tissue to EcN cells, but not MG1655 cells, was found to increase levels of extra-cellular 5-HT. These effects were not observed when tissues were treated with cell-free supernatant from bacterial cultures. In contrast, when supernatant recovered from untreated ileal tissue was pre-incubated with EcN, the derivative cell-free supernatant was able to elevate 5-HT overflow when used to treat fresh ileal tissue. Measurement of 5-HT precursors and metabolites indicated EcN also increases intracellular 5-HTP and reduces 5-HIAA. The former pointed to modulation of tryptophan hydroxylase-1 to enhance 5-HT synthesis, while the latter indicates an impact on clearance into enterocytes through SERT. Taken together, these findings show EcN is able to enhance 5-HT bioavailability in ileal tissues through interaction with compounds secreted from host tissues.

No MeSH data available.


Related in: MedlinePlus