Figure 1.

Type 2 Alveolar Epithelial Cells Induce IL-33 at Birth

(A) Whole-lung IL-33 quantification by ELISA at E19; postnatal days 1, 3, 5, 7, and 14 (P1–P14); and 3 and 4 weeks (3–4w) after birth.

(B) qRT-PCR of pulmonary Il33 expression in WT mice at E19 and P1.

(C) FACS analysis of viable citrine⁺ cells from Il33^Cit/+ mice at E19 exposed to vacuum or atmospheric pressure (control) for 6 hr.

(D) Quantification of (C).

(E) Whole-lung IL-33 quantification by ELISA of WT lungs at E19 exposed to vacuum or atmospheric pressure (control) for 6 hr.

(F) FACS analysis of lung CD45 and citrine expression in Il33^Cit/+ reporter mice at the indicated time points (gates are set using WT as controls).

(G) Percentage of Cit⁺CD45⁻ cells among lung cells, gated as in (F).

(H) Flow cytometry of viable CD45⁻ lung cells from Il33^Cit/+ mice at P7, stained for EpCam and CD31.

(I) Quantification of the Cit⁺ proportion of EpCAM⁺ cells between E19 and 8 weeks of age.

(J) Micrographs of lung sections at E19, P1, and P3 from Il33^Cit/+ reporter mice. Red, surfactant protein C (SP-C); green, IL-33-driven citrine. Scale bars represent 75 μm.

Data are representative of two independent experiments with three to five mice per time point, and graph bars represent mean ± SEM. ^∗∗p < 0.01 and ^∗∗∗∗p < 0.0001.