Gut bacterial aromatic amine production: aromatic amino acid decarboxylase and its effects on peripheral serotonin production

Abstract

Colonic luminal aromatic amines have been historically considered to be derived from dietary source, especially fermented foods; however, recent studies indicate that the gut microbiota serves as an alternative source of these amines. Herein, we show that five prominent genera of Firmicutes (Blautia, Clostridium, Enterococcus, Ruminococcus , and Tyzzerella ) have the ability to abundantly produce aromatic amines through the action of aromatic amino acid decarboxylase (AADC). In vitro cultivation of human fecal samples revealed that a significant positive correlation between aadc copy number of Ruminococcus gnavus and phenylethylamine (PEA) production. Furthermore, using genetically engineered Enterococcus faecalis -colonized BALB/cCrSlc mouse model, we showed that the gut bacterial aadc stimulates the production of colonic serotonin, which is reportedly involved in osteoporosis and irritable bowel syndrome. Finally, we showed that human AADC inhibitors carbidopa and benserazide inhibit PEA production in En. faecalis .

Hydroxyl-functionalized pillar[5]arene with high separation performance for gas chromatography

“…Their separation is indispensable for environmental protection since their own high toxicity. 37,38 However, their similarity in structure and properties makes their separation problematic in GC. Noteworthy, as the differences between the boiling points of the pairs of m -chloroaniline/ p -chloroaniline and m -bromoaniline/ p -bromoaniline are only 1–2 °C and the differences of dipole moments are only 0.38 Debye and 0.41 Debye, respectively, their separations in GC are extremely challenging.…”

Genetically proxied intestinal microbiota and risk of erectile dysfunction

“…Moreover, we found that Tyzzerella‐3 was a risk factor for ED in this MR study. Previous evidence showed that genus Tyzzerella of Firmicutes was associated with incident diabetes and abundant production of aromatic amines 8,39 . Meanwhile, it is reported that lower levels of Tyzzerella‐3 were associated with acute myocardial infarction, in which the SCFAs pathway was involved 40 .…”

“…Previous evidence showed that genus Tyzzerella of Firmicutes was associated with incident diabetes and abundant production of aromatic amines. 8,39 Meanwhile, it is reported that lower levels of Tyzzerella-3 were associated with acute myocardial infarction, in which the SCFAs pathway was involved. 40 Thus, it seems that dysbiosis of Tyzzerella-3 may mediate the endocrine or endothelial dysfunction through the SCFAs' pathway, which produce adverse effects on the erectile function.…”

Gut microbiota-derived tryptamine and phenethylamine impair insulin sensitivity in metabolic syndrome and irritable bowel syndrome

“…Besides the mechanistic insights into the contribution of R. gnavus-derived tryptamine and phenethylamine to the development of insulin resistance in IBS, a variety of bacteria species including Blautia hansenii, Enterocloster (Clostridium) boltae and Enterococcus faecalis and have also been shown to produce tryptamine and phenethylamine by recent studies 24,33 . Among these tryptamine and phenethylamine-producing bacteria species, R. gnavus has the highest catalytic ability to transform aromatic amino acids into aromatic trace amines (tryptamine, tyramine and phenethylamine) compared with other bacteria species 33 .…”

“…Besides the mechanistic insights into the contribution of R. gnavus-derived tryptamine and phenethylamine to the development of insulin resistance in IBS, a variety of bacteria species including Blautia hansenii, Enterocloster (Clostridium) boltae and Enterococcus faecalis and have also been shown to produce tryptamine and phenethylamine by recent studies 24,33 . Among these tryptamine and phenethylamine-producing bacteria species, R. gnavus has the highest catalytic ability to transform aromatic amino acids into aromatic trace amines (tryptamine, tyramine and phenethylamine) compared with other bacteria species 33 . To further uncover the role of gut dysbiosis that is involved in the development of insulin resistance in IBS, we also investigated the associations between these bacteria, tryptamine/phenethylamine and indicators of insulin resistance in IBS patients (Figure .S6H-M), providing supporting evidence for the increased abundances of other tryptamine and phenethylamine producers in metabolic syndrome.…”