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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

Role of E. coli Nissle 1917 K5 capsule in 5-HT overflow.The potential role of the EcN K5 capsule in 5-HT overflow was investigated using the isogenic K5 deficient mutants EcN∆kfiB and EcN∆kfiC (Nzakizwanayo et al.46). Ileal tissue samples were treated with live cell suspensions and extracellular 5-HT levels measured using amperometry as in Fig. 1. Data shown represent means ± S.E.M. (n = 4). KB - control samples incubated with Krebs buffer only; EcN- samples treated with E. coli Nissle 1917; MG1655 - samples treated with E. coli MG1655; KfiC - samples treated with EcN∆kfiC; KfiB- samples treated with EcN∆kfiB. ***p ≤ 0.001 vs KB; *p ≤ 0.01 vs KB.
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f2: Role of E. coli Nissle 1917 K5 capsule in 5-HT overflow.The potential role of the EcN K5 capsule in 5-HT overflow was investigated using the isogenic K5 deficient mutants EcN∆kfiB and EcN∆kfiC (Nzakizwanayo et al.46). Ileal tissue samples were treated with live cell suspensions and extracellular 5-HT levels measured using amperometry as in Fig. 1. Data shown represent means ± S.E.M. (n = 4). KB - control samples incubated with Krebs buffer only; EcN- samples treated with E. coli Nissle 1917; MG1655 - samples treated with E. coli MG1655; KfiC - samples treated with EcN∆kfiC; KfiB- samples treated with EcN∆kfiB. ***p ≤ 0.001 vs KB; *p ≤ 0.01 vs KB.

Mentions: Given the distinct impacts of EcN and MG1655 on extra cellular 5-HT in our ex-vivo system, we next sought to understand how key differences in these gut-associated strains of E. coli may account for their differential effects on 5-HT overflow. Although structurally and biochemically similar, a major distinguishing feature of EcN and MG1655 is the composition of the outer polysaccharide capsule, with EcN generating a K5 type capsule compared to the MG1655 K12 type capsule. Since these outer surface structures are often the point of contact between host and bacterial cells, and in light of the established role of the EcN K5 in host-microbe interactions4546, we hypothesized that the EcN K5 capsule may play a role in the observed EcN induced elevation of extra-cellular 5-HT. To test this, ileal tissue was treated with isogenic EcN capsule deficient mutants, EcN∆kfiB and EcN∆kfiC, in which core K5 biosynthesis genes are deleted46. These experiments showed K5 deficient mutants were still able to induce significantly elevated levels of extracellular 5-HT, comparable to those elicited by wild type EcN (Fig. 2), excluding a role of the K5 capsule in EcN mediated 5-HT overflow.


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)

Role of E. coli Nissle 1917 K5 capsule in 5-HT overflow.The potential role of the EcN K5 capsule in 5-HT overflow was investigated using the isogenic K5 deficient mutants EcN∆kfiB and EcN∆kfiC (Nzakizwanayo et al.46). Ileal tissue samples were treated with live cell suspensions and extracellular 5-HT levels measured using amperometry as in Fig. 1. Data shown represent means ± S.E.M. (n = 4). KB - control samples incubated with Krebs buffer only; EcN- samples treated with E. coli Nissle 1917; MG1655 - samples treated with E. coli MG1655; KfiC - samples treated with EcN∆kfiC; KfiB- samples treated with EcN∆kfiB. ***p ≤ 0.001 vs KB; *p ≤ 0.01 vs KB.
© Copyright Policy - open-access
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4663480&req=5

f2: Role of E. coli Nissle 1917 K5 capsule in 5-HT overflow.The potential role of the EcN K5 capsule in 5-HT overflow was investigated using the isogenic K5 deficient mutants EcN∆kfiB and EcN∆kfiC (Nzakizwanayo et al.46). Ileal tissue samples were treated with live cell suspensions and extracellular 5-HT levels measured using amperometry as in Fig. 1. Data shown represent means ± S.E.M. (n = 4). KB - control samples incubated with Krebs buffer only; EcN- samples treated with E. coli Nissle 1917; MG1655 - samples treated with E. coli MG1655; KfiC - samples treated with EcN∆kfiC; KfiB- samples treated with EcN∆kfiB. ***p ≤ 0.001 vs KB; *p ≤ 0.01 vs KB.
Mentions: Given the distinct impacts of EcN and MG1655 on extra cellular 5-HT in our ex-vivo system, we next sought to understand how key differences in these gut-associated strains of E. coli may account for their differential effects on 5-HT overflow. Although structurally and biochemically similar, a major distinguishing feature of EcN and MG1655 is the composition of the outer polysaccharide capsule, with EcN generating a K5 type capsule compared to the MG1655 K12 type capsule. Since these outer surface structures are often the point of contact between host and bacterial cells, and in light of the established role of the EcN K5 in host-microbe interactions4546, we hypothesized that the EcN K5 capsule may play a role in the observed EcN induced elevation of extra-cellular 5-HT. To test this, ileal tissue was treated with isogenic EcN capsule deficient mutants, EcN∆kfiB and EcN∆kfiC, in which core K5 biosynthesis genes are deleted46. These experiments showed K5 deficient mutants were still able to induce significantly elevated levels of extracellular 5-HT, comparable to those elicited by wild type EcN (Fig. 2), excluding a role of the K5 capsule in EcN mediated 5-HT overflow.

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