Deoxycholic acid modulates cell-junction gene expression and increases intestinal barrier dysfunction in Caco-2 cell monolayers

Authors: Zeng, Huawei; Safratowich, Bryan; CHENG, WEN-HSING - Mississippi State University; Larson, Kate; Briske Anderson, Mary

Submitted to: Molecular Nutrition and Food Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/19/2022
Publication Date: 1/22/2022
Citation: Zeng, H., Safratowich, B.D., Cheng, W., Larson, K.J., Briske Anderson, M.J. 2022. Deoxycholic acid modulates cell-junction gene expression and increases intestinal barrier dysfunction in Caco-2 cell monolayers. Molecular Nutrition and Food Research. https://doi.org/10.3390/molecules27030723.
DOI: https://doi.org/10.3390/molecules27030723

Interpretive Summary: The intestinal barrier serves as an important defense system by being physical and functional barriers against invading pathogens and potential toxins. Impaired intestinal barrier function is implicated in the development of colonic inflammation and cancer. Eating a high amount of dietary fat induces the release of bile acids from the gall bladder into the small intestine and colon and can compromise intestinal barrier integrity. However, the underlying molecular basis remains to be determined. In this cell culture study, we demonstrate that at physiological concentrations, colonic bile acids alter the gene expression of multiple membrane proteins related to intestinal barrier dysfunction. These data provide novel insights into how diet can modify intestinal barrier dysfunction and will be useful for scientists studying the prevention of obesity-related colon cancer.

Technical Abstract: Diet-related obesity is associated with an increased risk of developing intestinal hyperpermeability. High dietary fat intake causes an increase in colonic bile acids (BAs), particularly deoxycholic acid (DCA, a secondary BA), which may disrupt the intestinal epithelial barrier. To determine the potential role of bile acids in barrier dysfunction, we hypothesize that DCA modulates the gene expression in multiple cell junction pathways and increases intestinal permeability. Human intestinal Caco-2 cells were grown in monolayers and challenged with DCA at physiological, sub-mM, concentrations. DCA increased transcellular and paracellular permeability (> 20%) measured by transepithelial electrical resistance and phenol red flux. Similarly, DCA increased intracellular reactive oxidative species production (>100%) and accompanied a decrease (>40%) in extracellular signal-regulated kinase 1/2 (ERK1/2) signaling pathways. Further characterization of underlying genes related to epithelial barrier with PCR array analysis identified that 23 genes (tight junction, focal adhesion, gap junction and adherens junction pathways) were decreased at least 40% in (0.25 mM) DCA-treated Caco-2 cells when compared to untreated cells. Finally, we demonstrated that DCA decreased (>58%) the protein content of occludin present at the cellular tight junctions and the nucleus of epithelial cells. Collectively, our data suggest that at physiological concentrations, DCA alters the gene expression of multiple pathways related to cell junctions and increases permeability in a Caco-2 intestinal barrier model. These molecular events may represent the underlying mechanistic pathways that are responsible for DCA-induced transcellular and paracellular permeation.