The prebiotic inulin affects virulence factor expression in Candida albicans

Dietary supplementation with prebiotics such as inulin has been associated with a broad range of health benefits. However, the effects of inulin on the opportunistic fungal pathogen Candida albicans, which resides as a commensal in the gut, have not been characterized. Here, RNA sequencing revealed that inulin affects the expression of C. albicans genes associated with cell wall construction, adhesion, and yeast-hypha morphogenesis. Consistent with these changes in gene expression, inulin inhibited hyphal development, increased adhesion to human Caco-2 and A431 cells, decreased the thickness of the inner layer of the C. albicans cell wall, reduced the exposure of cell wall pathogen-associated molecular patterns [β-(1,3)-glucan and chitin], and affected antifungal drug sensitivity. These changes impacted host immune recognition and cytokine responses, ultimately attenuating the virulence of C. albicans in an invertebrate infection model. Therefore, dietary supplementation with inulin is likely to influence host-fungus interactions.IMPORTANCEThe benefits of prebiotic dietary supplements, such as inulin (a natural plant dietary fiber), are thought to include a healthier gut microbiome, a reduced risk of colon cancer, and lower cholesterol levels. Unsurprisingly, prebiotic usage is increasing rapidly. However, while the effects of prebiotics upon gut bacteria have been characterized, the impacts upon Candida albicans, an opportunistic fungal pathogen that resides in the human gut, have remained obscure. We show that inulin affects the expression of virulence-related phenotypes and antifungal drug sensitivity in Candida. Furthermore, we show that inulin reduces the virulence of this fungus in an invertebrate model, consistent with the idea that inulin may lower the risk of fungal infection in healthy individuals.