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

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.

Bioactive Polyphenols and Neuromodulation: Molecular Mechanisms in Neurodegeneration

“…It has been shown that Streptococcus, Escherichia and Enterococcus spp. produce serotonin [143,144] and that Bifidobacterium infantis can modulate central serotonin transmission by increasing plasma tryptophan levels [145]. Meanwhile, different Lactobacillus and Bifidobacterium species are able to produce γ-aminobutyric acid (GABA), the principal inhibitory neurotransmitter in the central nervous system [146].…”

Dysbiosis contributes to chronic constipation development via regulation of serotonin transporter in the intestine

“…Furthermore, pervious research shown that Clostridia can modulate 5-HT signalling through production of soluble metabolites that influence 5-HT synthesis, and affect both gastro-intestinal motility through this mechanism 18 . Recent study showed that Escherichia coli Nissle 1917 can enhance 5-HT bioavailability in gut tissues through interaction with compounds secreted from host 19 . Serotonin transporter (SERT) is the main regulator of extracellular 5-HT availability 20 .…”

The nutrient‐sensing repertoires of mouse enterochromaffin cells differ between duodenum and colon

“…These are able to produce their own unique products including short‐chain fatty acids (SCFA) from the breakdown of carbohydrates that are indigestible by the host. Short‐chain fatty acids increase 5‐HT bioavailability in a number of experimental settings, , and it is suggested that the interaction of SCFAs with free fatty acid receptor 2 (FFAR2) may mediate this response . Clear evidence for this in primary EC cells has not yet been provided.…”