Mapping of liver-enriched transcription factors in the human intestine

AIM: To investigate the gene expression pattern of hepatocyte nuclear factor 6 (HNF6) and other liverenriched transcription factors in various segments of the human intestine to better understand the differentiation of the gut epithelium. METHODS: Samples of healthy duodenum and jejunum were obtained from patients with pancreatic cancer whereas ileum and colon was obtained from patients undergoing right or left hemicolectomy or (recto)sigmoid or rectal resection. All surgical specimens were subjected to histopathology. Excised tissue was shock-frozen and analyzed for gene expression of liver-enriched transcription factors by semiquantitative reverse transcription polymerase chain and compared to the human colon carcinoma cell line Caco-2. Protein expression of major liver-enriched transcription factors was determined by Western blotting while the DNA binding of HNF6 was investigated by electromobility shift assays. RESULTS: The gene expression patterning of liverenriched transcription factors differed in the various segments of the human intestine with HNF6 gene expression being most abundant in the duodenum (P < 0.05) whereas expression of the zinc finger protein GATA4 and of the HNF6 target gene ALDH3A1 was most abundant in the jejunum (P < 0.05). Likewise, expression of FOXA2 and the splice variants 2 and 4 of HNF4α were most abundantly expressed in the jejunum (P < 0.05). Essentially, expression of transcription factors declined from the duodenum towards the colon with the most abundant expression in the jejunum and less in the ileum. The expression of HNF6 and of genes targeted by this factor, i.e. neurogenin 3 (NGN3) was most abundant in the jejunum followed by the ileum and the colon while DNA binding activity of HNF4α and of NGN3 was conf irmed by electromobility shift assays to an optimized probe. Furthermore, Western blotting provided evidence of the expression of several liver-enriched transcription factors in cultures of colon epithelial cells, albeit at different levels. CONCLUSION: We describe significant local and segmental differences in the expression of liver-enriched transcription factors in the human intestine which impact epithelial cell biology of the gut.

Impact of host genetics on gut microbiome: Take-home lessons from human and mouse studies

The intestinal microbiome has emerged as an important component involved in various diseases.Therefore,the interest in understanding the factors shaping its composition is growing.The gut microbiome,often defined as a complex trait,contains diverse components and its properties are determined by a combination of external and internal effects.Although much effort has been invested so far,it is still difficult to evaluate the extent to which human genetics shape the composition of the gut microbiota.However,in mouse studies,where the environmental factors are better controlled,the effect of the genetic background was significant.The purpose of this paper is to provide a current assessment of the role of human host genetics in shaping the gut microbiome composition.Despite the inconsistency of the reported results,it can be estimated that the genetic factor affects a portion of the microbiome.However,this effect is currently lower than the initial estimates,and it is difficult to separate the genetic influence from the environmental effect.Additionally,despite the differences between the microbial composition of humans and mice,results from mouse models can strengthen our knowledge of host genetics underlying the human gut microbial variation.

Intestinal Transport and Biotransformation of Resibufogenin and Cinobufagin in Chan Su via HPLC/APCI-MS^n

In vitro models of human colon carcinoma cell line(Caco-2 cell monolayer) and human intestinal bacteria were used to investigate the intestinal transport and biotransformation of resibufogenin and cinobufagin in Chan Su by HPLC/APCI-MSn. The experimental results of Caco-2 cell monolayer demonstrate that the apparent permeability coefficients(Papp) of resibufogenin and cinobufagin are higher than 10–6 cm/s, which indicates that both resibufogenin and cinobufagin have a good absorption in the small intestine. And the biotransformation result of human intestinal bacteria shows that resibufogenin has been transformed to 3-epiresibufogenin and cinobufagin has been transformed to 3-epicinobufagin, deacetylcinobufagin and 3-epideacetycinobufagin, respectively.

Transformation of trollioside and isoquercetin by human intestinal flora in vitro

The present study was designed to determine the intestinal bacterial metabolites of trollioside and isoquercetin and their antibacterial activities. A systematic in vitro biotransformation investigation on trollioside and isoquercetin, including metabolite identification, metabolic pathway deduction, and time course, was accomplished using a human intestinal bacterial model. The metabolites were analyzed and identified by HPLC and HPLC-MS. The antibacterial activities of trollioside, isoquercetin, and their metabolites were evaluated using the broth microdilution method with berberine as a positive control, and their potency was measured as minimal inhibitory concentration(MIC). Our results indicated that trollioside and isoquercetin were metabolized by human intestinal flora through O-deglycosylation, yielding aglycones proglobeflowery acid and quercetin, respectively The antibacterial activities of both metabolites were more potent than that of their parent compounds. In conclusion, trollioside and isoquercetin are totally and rapidly transformed by human intestinal bacteria in vitro and the transformation favors the improvement of the antibacterial activities of the parent compounds.

Anti-mutagenicity of Swertiamarin and Its Metabolite in Incubated System of Human Intestinal Flora

Objective To study the biotransformation regulation and pharmacological effect of swertiamarin and its metabolite in incubated system of human intestinal flora. Methods Incubated system of human intestinal flora was utilized to research the intestinal metabolism of swertiamarin. Furthermore, mutagenic test and anti-mutagenic test were carried out to research the activity relationship of swertiamarin and its metabolite. Results Gentianine was found in the metabolites of swertiamarin. The pharmacological experiment indicated that swertiamarin and its metabolite both had good anti-mutagenic effect. Conclusion Swertiamarin is partly metabolized to gentianine after oral administration. They show similar anti-mutagenicity effects.

UFLC-DAD-ESI-IT-TOFMSn Analysis on Biotransformation of Tongmai Formula Incubated with Human Intestinal Bacteria

Objective To investigate the biotransformation of Tongmai formula（TMF） in incubated system of human intestinal flora（HIF）. Methods The technique of ultra fast liquid chromatography with diode array detector and coupled with electrospray ionization ion trap time-of-flight multistage mass spectrometry（UFLC-DAD-ESIIT-TOFMSn） was adopted to determine the products of TMF biotransformed by HIF. Results Totally 66 constituents were detected and identified according to the accurate mass measurements（〈 5 ppm） and effective MSn fragment ions. Meanwhile, the potential biotransformational pathways of compounds in TMF transformed by HIF were firstly proposed. Desugarization, hydroxylation, and methylation were the major reactions in the biotransformation mechanism of TMF by HIF. Conclusion This study will be helpful to clarify the material basis of pharmacological activities from TMF in vivo.