Figure 1. Flagellin-Mediated Upregulation of RegIIIγ Requires TLR5 Signaling and IL-22 Expression in Distinct Cell Populations.

(A) Messenger RNA (mRNA) transcript expression for RegIIIγ in the small intestine (SI) was measured by quantitative PCR (qPCR) at the indicated time periods following intravenous (i.v.) injection flagellin (Flg) or PBS (Ctrl). (n = 3 – 4 mice per time point).

(B) Messenger RNA was extracted from the SI lamina propria of wild-type (WT) or IL-22-deficient (Il22^−/−) mice 24 hours following i.v. injection of flagellin (n = 3 mice per group) and quantified by qPCR.

(C) IL-22 messenger RNA expression was measured in the SI lamina propria at the indicated time points following i.v. flagellin administration. IL-22 protein concentrations were detected in the serum by ELISA (n = 3 mice per time point).

(D – E) Mixed bone marrow (BM) chimeric mice reconstituted with a equal ratios of Tlr5^−/−, Il22^−/−, or WT BM, as indicated on the horizontal axis, were assessed for responsiveness to flagellin by qPCR analysis of RegIIIγ mRNA transcripts in the SI (D) and IL-22 mRNA in the SI lamina propria (E). IL-22 protein concentrations in the serum were measured by ELISA (F) (n = 3 – 4 mice per group). RegIIIγ expression was measured 24 hours after flagellin administration while serum IL-22 protein and lamina propria IL-22 expression were measured 3 hours after flagellin administration. Error bars show ± s.e.m. Data are representative of at least two independent experiments.