Probiotic Bifidobacterium species: potential beneficial effects in diarrheal disorders. Focus on “Probiotic Bifidobacterium species stimulate human SLC26A3 gene function and expression in intestinal epithelial cells”

diarrhea caused by enteric (bacterial/viral/parasitic) infections or diarrhea associated with inflammatory bowel disease represents a major health care burden worldwide (10). In addition, diarrhea associated with antibiotic administration in adults, as well as children, is a significant health care issue (1, 3). Diarrhea is also a common side effect of chemo/radiotherapy during cancer treatment (6). Antidiarrheal drugs generally have been shown to cause nausea, loss of appetite, and constipation, which often hinder treatment protocols (15). Diarrhea is a consequence of the imbalance of water and ion absorption by epithelial cells of the gastrointestinal tract, ultimately leading to enhanced secretion and/or diminished absorption of fluid and electrolytes. Aberrant ion movement across epithelia can occur through a paracellular pathway via tight junctions or a transcellular pathway via membrane transporters such as Na+-dependent glucose transporter 1, Na+/H+ exchanger isoform 3, Cl−/HCO3− exchanger, and downregulated in adenoma (DRA), which can be dysregulated in diarrhea (10). Infectious pathogens can alter ion transporters directly or may induce electrolyte imbalance via increased inflammation or reduction in the absorptive capacity of the epithelial cells (12). Several studies of the functional implication of DRA in diarrheal disorders have been published (4, 7, 13).