A decrease in anaerobic bacteria promotes Candida glabrata overgrowth while beta-glucan treatment restores the gut microbiota and attenuates colitis

Overview & Synopsis

BACKGROUND: The intestinal microbiota plays a crucial role in the maintenance of gut homeostasis. Changes in crosstalk between the intestinal epithelial cells, immune cells and the microbiota are critically involved in the development of inflammatory bowel disease. In the experimental mouse model, the development of colitis induced by dextran sulfate sodium (DSS) promotes overgrowth of the opportunistic yeast pathogen . Conversely, fungal colonization aggravates inflammatory parameters. In the present study, we explored the effect of colonization on the diversity of the gut microbiota in a DSS-induced colitis model, and determined the impact of soluble β-glucans on -host interactions. RESULTS: Mice were administered a single inoculum of and were exposed to DSS treatment for 2 weeks in order to induce acute colitis. For β-glucan treatment, mice were administered with soluble β-glucans purified from (3 mg per mouse), orally and daily, for 5 days, starting on day 1. The number of colonies and changes in microbiota diversity were assessed in freshly collected stool samples from each tagged mouse, using traditional culture methods based on agar plates. An increase in and populations and a reduction in and were observed during colitis development. This decrease in was significantly accentuated by overgrowth. Oral administration of β-glucans to mice decreased the overgrowth of aerobic bacteria and IL-1β expression while and populations increased significantly. β-glucan treatment increased IL-10 production via PPARγ sensing, promoting the attenuation of colitis and elimination. CONCLUSIONS: This study shows that the colonic inflammation alters the microbial balance, while β-glucan treatment increases the anaerobic bacteria and promotes colitis attenuation and elimination.