Figure 4. Il17c induction in the gut epithelium of DUOX2 deficient mice is T cell–independent and mimicked by impairment of the supraepithelial mucus layer.

(A and B) Il17c mRNA expression in the terminal ileum and colon of Duoxa^–/– (n = 26) and WT (n = 22) littermates. Arrows indicate samples with outlier high Il17c expression (Il17c^hi). Ccl20 (C), Il17a (D), and Il17f (E) expression in the terminal ileum. Two-tailed Mann-Whitney. (F and G) Expression of Il17c in the ileum and colon of intestinal epithelial-specific Duoxa^–/– and floxed littermate control mice. We challenged the normal bacterial compartmentalization by chronically feeding the emulsifier CMC (1% wt/vol in drinking water for 8 weeks) that thins the mucus layer (12). n = 6 and n = 17 for floxed control mice without or with CMC treatment, respectively, and n = 5 and n = 20 for intestinal epithelial-specific Duoxa^–/– mice without or with CMC treatment, respectively. Kruskal-Wallis and Dunn’s post hoc test. (H and I) Il17c expression is preserved in Rag1^–/– mice lacking T cells as a major source of IL-17 family cytokines. n = 11 for Rag1^–/–, Duoxa^fl/fl mice; n = 9 for Rag1^–/–, Duoxa^fl/fl, Vil1-Cre mice. Two-tailed Mann-Whitney. *P < 0.05; **P < 0.01; ***P < 0.001. Error bars in A–I indicate 95% CI of geometric means.