Abstract / Summary
The intestinal epithelial barrier maintains gut homeostasis and limits systemic inflammation. Barrier dysfunction is linked to metabolic disorders including diabetes, yet the combined effects of hyperglycemia, microbial metabolites, and dietary polysaccharides on epithelial integrity remain unclear. This study evaluated acute hyperglycemia, secondary bile acids, and structurally distinct pectins using an in vitro epithelial co-culture model. Barrier integrity was assessed under normoglycemic (5 mM) and hyperglycemic (20 mM) conditions following calcium ionophore disruption. Acute hyperglycemia alone did not exacerbate A23187-induced barrier disruption. Secondary bile acids partially restored integrity, with unsulfated deoxycholic acid showing the strongest effect, reaching normalized area under de curve values of 95% and 94% of untreated control under normoglycemic and acute hyperglycemic conditions, respectively. Secondary bile acids showed treatment-specific barrier-protective effects, with numerical differences between sulfated and unsulfated forms. Pectins showed preparation-specific differences in barrier protection that could not be attributed to individual structural parameters because multiple physicochemical characteristics varied simultaneously. Under acute hyperglycemic conditions, all tested pectins significantly attenuated A23187-induced barrier disruption, whereas significant protection was observed for selected preparations under normoglycemic conditions. Deoxycholic acid increased Claudin-1 and Occludin mRNA expression under acute hyperglycemic conditions, although these changes were not validated at the protein level or causally linked to functional barrier recovery. Secondary bile acid composition and pectin structural properties modulated epithelial barrier responses in this model. As dysbiosis can deplete microbiota-derived secondary bile acids, structurally defined pectins may help compensate for this loss and preserve intestinal barrier function.