Colonic Absorption of Low-Molecular-Weight Metabolites Influenced by the Intestinal Microbiome: A Pilot Study

Abstract

Low-molecular-weight metabolites produced by the intestinal microbiome play a direct role in health and disease. However, little is known about the ability of the colon to absorb these metabolites. It is also unclear whether these metabolites are bioavailable. Here, metabolomics techniques (capillary electrophoresis with time-of-flight mass spectrometry, CE-TOFMS), germ-free (GF) mice, and colonized (Ex-GF) mice were used to identify the colonic luminal metabolites transported to colonic tissue and/or blood. We focused on the differences in each metabolite between GF and Ex-GF mice to determine the identities of metabolites that are transported to the colon and/or blood. CE-TOFMS identified 170, 246, 166, and 193 metabolites in the colonic feces, colonic tissue, portal plasma, and cardiac plasma, respectively. We classified the metabolites according to the following influencing factors: (i) the membrane transport system of the colonocytes, (ii) metabolism during transcellular transport, and (iii) hepatic metabolism based on the similarity in the ratio of each metabolite between GF and Ex-GF mice and found 62 and 22 metabolites that appeared to be absorbed from the colonic lumen to colonocytes and blood, respectively. For example, 11 basic amino acids were transported to the systemic circulation from the colonic lumen. Furthermore, many low-molecular-weight metabolites influenced by the intestinal microbiome are bioavailable. The present study is the first to report the transportation of metabolites from the colonic lumen to colonocytes and somatic blood in vivo, and the present findings are critical for clarifying host-intestinal bacterial interactions.

Recent advances in capillary electrophoresis‐mass spectrometry: Instrumentation, methodology and applications

“…Rodents, rats and mice mainly, are frequently used as model organisms for basic research on metabolism. Metabolic profiling was performed on rodent muscle , heart , liver , brain , intestinal and glioma tissue, arterial cells as well as on rodent serum/plasma , urine and feces . CE‐MS was furthermore used for research on the metabolism of microorganism , plants and mushroom .…”

Metabolite Profiling of Feces and Serum in Hemodialysis Patients and the Effect of Medicinal Charcoal Tablets

“…5-Aminovalerate and 3-methyl-2-oxovalerate are degradation products of lysine and isoleucine, respectively, which could be generated by gut microflora metabolism [21,22]. Especially, 5-aminovalerate is thought to be mainly a microbial metabolite produced by the gut microflora [21,23]. The elevation in the fecal content of 5-aminovalerate and 3-methyl-2-oxovalerate suggests increased bacterial processing of dietary proteins in uremic patients.…”

“…3-Phenylpropionic acid is an endogenous and microbial product in the phenylalanine metabolic pathway [23,26]. The reason for its decrease is unclear, but is probably due to the alteration of intestinal flora populations in uremic patients.…”

Changes in Intestinal Microbiota and Predicted Metabolic Pathways During Colonic Fermentation of Mango (Mangifera indica L.)—Based Bar Indigestible Fraction

“…The intestinal microbiota plays an important role in the physiological well-being of people, which is related directly to stimulation by bacterial cell components and the effects of bacterial metabolites [18]. Various approaches have focused on studying the intestinal microbiota either by quantitative techniques of microorganism culture [9] or by quantifying 16s rRNA fragment as a marker-gene.…”