Figure 1. Commensal fungi are present in the intestine and are recognized by Dectin-1.

(A) Prevalence of fungi in mucosa isolated from ileum, caecum, proximal (prox) and distal (dist) colon of C57BL/6J mice. ITS1-2 rDNA level was analyzed by qPCR and normalized to β-actin DNA. (B) Visualization of commensal fungi in the intestine. Colon sections were stained with a soluble Dectin-1 probe (sDEC-1) and counterstained with DAPI. The DAPI signal has been amplified in lower panels (B) to show that DAPI-stained bacteria and fungi are in close proximity to each other. (C) Intestinal fungi are recognized by Dectin-1. Fecal pellets were homogenized and labeled with sDEC-1 in presence (gray histogram) or absence (black histogram) of laminarin (a soluble β-glucan) to block specific binding. Binding was assessed by flow cytometry (left panels). Dectin-1-binding fungi were sorted (right panels) and visualized by confocal microscopy. (D) ASCA generation after DSS colitis. Mice were exposed twice to 2.5% DSS-supplemented water for 7 days each separated by two weeks of recovery. Serum samples were collected before DSS treatment (day 0) and 2 weeks after the last DSS cycle (42 days total) and ASCA IgM and IgG were measured by ELISA. Each symbol represents a mouse, all error bars indicate the s.d. *P < 0.05; unpaired t test. All data are representative of at least two independent experiments with similar results.