Growth stimulation of Bifidobacterium from human colon using daikenchuto in an in vitro model of human intestinal microbiota.

Daikenchuto (DKT) is a Japanese traditional herbal (Kampo) medicine containing ginseng, processed ginger, and Japanese or Chinese pepper. We aimed to determine how DKT affects human colonic microbiota. An in vitro microbiota model was established using fecal inocula collected from nine healthy volunteers, and each model was found to retain operational taxonomic units similar to the ones in the original human fecal samples. DKT was added to the in vitro microbiota model culture at a concentration of 0.5% by weight. Next-generation sequencing of bacterial 16S rRNA gene revealed a significant increase in the relative abundance of bacteria related to the Bifidobacterium genus in the model after incubation with DKT. In pure cultures, DKT significantly promoted the growth of Bifidobacterium adolescentis, but not that of Fusobacterium nucleatum or Escherichia coli. Additionally, in pure cultures, B. adolescentis transformed ginsenoside Rc to Rd, which was then probably utilized for its growth. Our study reveals the in vitro bifidogenic effect of DKT that likely contributes to its beneficial effects on the human colon.

A simple three-dimensional gut model constructed in a restricted ductal microspace induces intestinal epithelial cell integrity and facilitates absorption assays.

The intestine acts as a center for nutrient and water absorption at the epithelium and plays an important role in immunity. Considering the complexity of its function and roles in living systems, a physiologically relevant gut in vitro model is desirable in both basic biology and the analysis of effects of some substances on functions of the gut; these analyses include the screening of drug and food candidates with regard to intestinal disorder at an early stage of medical development. In the present study, we constructed a three-dimensional (3D) gut model using human absorptive enterocytes (CACO-2 cells) by reconstitution of the gut epithelial sheet restricted on a high-reproducible ductal scaffold of collagen gel. Moreover, using the 3D gut model, we evaluated the morphology at the cellular and tissue levels and conducted a phenotypic analysis of the intestinal physiological functions, which involved a permeability assay mimicking barrier disruption inducing inflammation and an absorption assay reflecting ingestive effects. The ductal structure, in vivo-like 3D epithelial structures, epithelial barrier, and effective absorptive function characterized the 3D gut model. The epithelial cells formed a villus-like buckling epithelium, vertical microvilli of increased density on the cell surface, and a crypt-like localized cell proliferating region. The mature shape of the epithelium may contribute to mimicking barrier function and effective absorption compared with that in the 2D gut model. Furthermore, we successfully mimicked the dextran sodium sulfate-induced epithelial barrier dysfunction as a trigger phenomenon of gut inflammation in the 3D gut model. The integrity of the epithelium and phenotypic analysis of the intestinal physiological functions in the simple and reproducible 3D gut model will allow for a drug screening system for assessing the effects on the functions of the gut epithelium from the lumen side.