IL-33 indirectly promotes tolerogenic CD103+ DC development and Treg expansion via activating IECs. (A) Colonic epithelial cells were collected to analyze the ST2L expression by flow cytometry and PCR. (B, C) Colonic epithelial cells were extracted from normal mice, and colitis mice were treated with rIL-33 or PBS on d 4 after TNBS inoculation, followed by total RNA, and cultural supernatants were harvested. TSLP, TGF7#x03B2;1 and ALDH1A1 mRNA was assessed by quantitative real-time PCR (B), and CD103+ expression on BMDCs was analyzed by flow cytometry after incubation with epithelial cells supernantants or culture medium (CM) (C). Data represent mean ± SD per group (n = 6-8/group). The data shown are representative one of three separate experiments. *p < 0.05. (D–F) Colonic epithelial cells of colitis mice were activated with IL-33 24 h or not in vitro. (D) Expression of genes encoding TSLP, TGFβ1 and ALDH1A1 was assessed by quantitative real-time PCR. (E) BMDCs conditioned by supernatants of colonic epithelial cells were subjected to assess expression of CD103. (F) CD4+CD25−T cells were cocultured with BMDCs educated by above supernatants or supernatant of epithelial cells from normal mice, followed by analysis of CD4+Foxp3+ differentiation and proliferation response. Results represent mean ± SD. The data shown are representative one of three separate experiments. *p < 0.05.