Fig. 3: Bilirubin causes remission of ILC2-driven allergic airway inflammation.

a–f WT mice were intranasally administered with papain or PBS 6 h after unconjugated bilirubin (UCB) or vehicle (Veh) treatment for consecutive 5 d (n = 4–6 per group). Mice were sacrificed 24 h after the last treatment. a The frequencies and number of eosinophils in BAL were evaluated by flow cytometry. b The amount of IL-5 and IL-13 in BAL was measured by ELISA. c Representative H&E staining of lung sections (bars, 100 um). d The proliferation of lung ILC2s was determined by Ki-67 staining. e The frequencies of lung ILC2s and IL-5⁺IL-13⁺ ILC2s were determined by flow cytometry. Cells were stimulated with cocktail for 4 h. f The statistical results of e. g–l WT mice were intranasally challenged with extract of Alternaria alternata for 4 d (n = 6 per group). Mice were sacrificed 24 h after the last treatment. The number (g) and the proliferation (h) of lung ILC2s were evaluated by flow cytometry. i The frequencies of IL-5⁺IL-13⁺ ILC2s in lungs after cell stimulation cocktail treatment for 4 h. j The absolute number of eosinophils in BAL. k The amounts of IL-5 and IL-13 in BAL were measured by ELISA. l Representative H&E staining of lung sections (bars, 100 um). Data are representative of two (g–l) to three (a–f) independent experiments. Error bars show mean ± SEM; *p < 0.05; **p < 0.01; ***p < 0.001 by unpaired Student’s t test. Numbers within flow plots indicate the percentages of cells gated.