Figure 5.

Innate immune cells protect mice from DSS-induced colitis upon IL-33 treatment. (A) To investigate the role of innate immune cells, DSS was administered to RAG2^-/- mice for 6 days, followed by one day of normal drinking water. Mice were injected i.p. either with PBS or with IL-33 on day 0, 2 and 5 (n = 3-9 mice per group). (B) Body weight change and (C) disease activity index were monitored daily. (D) Histopathological score of PBS and IL-33-treated RAG2^-/- mice was assessed on day 7, and (E) representative H&E staining of colon sections were analyzed (n = 4). Scale bars represent 100 µm. (F) Levels of IL-33, TNF-α, IL-6, IL-5 and IL-13 were measured in colonic explants using Luminex technology. (G) Immune cells were isolated from the colonic lamina propria and the frequencies of lineage^-ICOS⁺ST2⁺ ILC2s were analyzed by flow cytometry. All data are presented as mean ± SEM. Statistical analyses were performed using two-way ANOVA followed by Tukey’s multiple comparison (B, C), unpaired Student’s t-test (D), or one-way ANOVA followed by Dunn’s or Dunnett’s multiple comparison test (F, G). *P < 0.05; **P < 0.01; ***P < 0.001.