Differential stimulation of peripheral blood mononuclear cells in Crohn's disease by fungal glycans.

Crohn's disease (CD) is characterized by loss of tolerance to intestinal microorganisms. This is reflected by serological responses to fungal glycans such as mannan and β-glucans. Fungal glycans have various effects on immune cells. However, the evidence for their effects in CD is vague. This study aimed to assess the effects of fungal cell wall glycans on human peripheral blood mononuclear cells (PBMCs) from CD and control patients. Human PBMCs from CD and control patients were stimulated by fungal cell wall glycans. Cytokine secretion was detected by ELISA and glycan receptor expression by flow cytometry. Mannan, β-glucans (curdlan), chitosan, and zymosan induced the secretion of interleukin (IL)-1β, IL-6, IL-23, IL-10, and tumor necrosis factor-α by PBMCs. Spleen tyrosin kinase and Src tyrosine kinase were involved in the response to mannan and β-glucans. Mannan and whole yeast cells induced a significantly higher pro-inflammatory cytokine response in CD compared with control patients. The results may suggest that CD is characterized by hyperresponsiveness to fungal glycans. Thus, glycans may potentially be triggering or perpetuating inflammation.