Inchinkoto, the Traditional Japanese Kampo Medicine, Enhances Intestinal Epithelial Barrier Function In Vitro

Abstract

Inchinkoto (ICKT), a traditional herbal medicine that is often used as a hepatoprotective drug in Japan, has pharmacological properties that include antioxidant, anti-inflammatory, and choleretic actions. Genipin is a metabolite of geniposide and the most abundant ingredient of ICKT; furthermore, it is considered to be the active substance responsible for its pharmacological properties in the liver. Drugs with such pharmacological characteristics are expected to prevent intestinal barrier dysfunction, which causes inflammatory bowel diseases (IBDs). However, no studies have investigated the effects of ICKT on the intestinal epithelial barrier. Therefore, we investigated the activity of ICKT in intestinal tight junctions by using cultured Caco-2 cell monolayers. The action of the compound on tight junctions was examined by measuring transepithelial electrical resistance (TEER) and sodium fluorescein (Na-F) permeability in the presence or absence of lipopolysaccharide (LPS). Moreover, the expression of the tight junction protein claudin-1 was assessed by using immunofluorescent staining. ICKT and genipin increased TEER and decreased Na-F permeability, which was suggestive of enhanced intestinal epithelial barrier function. Moreover, they prevented the LPS-induced destruction of the barrier, i.e., a decrease in TEER and an increase in Na-F permeability. Immunofluorescence staining revealed a high claudin-1 expression level on the cell surface, whereas exposure to LPS downregulated claudin-1. In turn, ICKT and genipin prevented the LPS-mediated reduction of claudin-1. These results suggest that ICKT enhances intestinal epithelial barrier function by upregulating claudin-1. Furthermore, genipin contributed to these effects. ICKT may be a promising medicine for the prevention and treatment of diseases associated with intestinal barrier disruption, such as IBD, obesity, and metabolic disorders.

An UHPLC–QTOF–MS‐based strategy for systematic profiling of chemical constituents and associated in vivo metabolites of a famous traditional Chinese medicine formula, Yinchenhao decoction

“…In addition, oral administration of a geniposide and chlorogenic acid combination ameliorated nonalcoholic steatohepatitis by modulating the gut microbiome composition and protecting the gut barrier. It was also found that the regulation of the microbiome contributed to the anti‐obstructive jaundice effect of YCHD (Yamashita et al, 2022), and the enhancement of the intestinal epithelial barrier may be closely associated with the therapeutic effect of YCHD in metabolic disorders (Nakao et al, 2022). Therefore, we hypothesized that chemical compounds found in feces might be able to modulate gut microbiota and influence the progression of liver disease.…”

Shoseiryuto Promotes the Formation of a Tight‐Junction Barrier in Cultured Human Bronchial Epithelial Cells

“…In the cell-culture experiments, noncytotoxic concentrations must be used to accurately assess the efficacy of test substances [ 11 , 12 ]. The maximum cell-exposure duration for SST in this experimental design was 4 days.…”

“…The concentration of LPS (1 mg/mL) used to induce TJ-barrier dysfunction in the present study was high compared to those used in other studies. Previously, we used LPS at a concentration of 100 μ g/mL to induce disruption of the Caco-2 cell intestinal epithelial barrier [ 11 ] and blood-brain barrier formed by the coculture of rat brain endothelial cells, pericytes, and astrocytes [ 17 ]. This may be attributed to the differences in cell types and experimental conditions.…”

“…TEER values and Na-F permeability were measured according to previously reported procedures [ 11 ]. In brief, an EVOM3 epithelial voltage resistance meter (World Precision Instruments, Sarasota, Florida, USA) equipped with the STX2-plus “chopstick” electrodes was used to measure TEER values ( Figure 2 ).…”

“…It has been reported that transepithelial electrical resistance (TEER) between cell monolayers increases with TJ barrier formation and decreases with weakening. Conversely, intercellular permeability (i.e., paracellular permeability) of small molecules, such as sodium fluorescein (Na-F) and fluorescein isothiocyanate dextran, decreases with barrier formation and increases with barrier weakening [ 11 ]. Therefore, we assessed TJ-barrier function by measuring TEER and the Na-F permeability of a cultured-cell monolayer.…”