Figure 5. High Il17c expression in the intestinal epithelium of DUOX2-deficient mice is linked to the expansion of gram-negative pathobionts.

(A) Differential microbiota-dependent regulation of Il17c, Il17a, and Reg3g (IL-22 target gene) in the mouse intestine. GF, germ-free; CONV, conventionalized (SPF); SFB^mono, monocolonized with segmented filamentous bacteria. n = 5 animals per condition. Data represent median expression values with IQR. Kruskal-Wallis with Dunn’s post hoc test. (B) Mice were treated for 3 days with an antibiotics (Abx) regimen comprising ciprofloxacin and metronidazole that suppresses the gram-negative gut microbiota (see Supplemental Figure 4). n = 6 and n = 5 for control mice without or with Abx treatment, respectively, and n = 8 and n = 4 for intestinal epithelial-specific Duoxa^–/– mice without or with Abx treatment, respectively. Data represent geometric means with 95% CI. Kruskal-Wallis test with Dunn’s post hoc test. (C) Acute cell-autonomous induction of Il17c expression in enteroid-derived epithelial monolayers directly exposed to bacteria. Each treatment was performed on 6 independent enteroid cultures derived from 3 Duoxa^–/–/WT littermate pairs. Bars indicate median expression values. Kruskal-Wallis with Dunn’s post hoc test. (D) Cladogram (phylum to genus level) depicting results of LEfSe (54) analysis identifying taxa with distinct relative abundance (P < 0.01; LDA > 2) in ileal mucosa of Duoxa^–/– (n = 26) compared with WT (n = 22) littermates. (E) Discriminative taxa in the ileal mucosal microbiota of Il17c^hi animals (marked with arrows in Figure 4A). (F) The relative mucosal abundance of genus Helicobacter. Data represent median values with IQR. Two-tailed Mann-Whitney. (G) The relative abundance of Proteobacterium otu0194 vs mucosal Il17c expression. Arrows in F and G indicate animals classified as Il17c^hi in Figure 4A. *P < 0.05; **P < 0.01; ***P < 0.001.