Figure 6.

Oxygen Tension Functions as an Important Switch between Injury and Regeneration

(A) Scheme of mature ALI cultures exposed to 2% O₂ for up to 48 h while still maintaining ALI.

(B–P) Staining for H&E (B, E, H, K, N), UEA1 (goblet cells; C, F, I, L, O), and Ki67 (D, G, J, M, P) on monolayers after exposed to 2% O₂ for 0 (B–D), 4 (E–G), 8 (H–J), 24 (K–M), and 48 h (N–P).

(Q and R) qPCR assays showing relative expression of UPR target genes (Q) and genes involved in epithelial regenerative responses (R) in monolayers exposed to 2% O₂ for the indicated time periods. Results were expressed relative to the 0 h time point. Mean ± SD are shown. n = 3 samples/group.

(S–U) Immunohistochemical staining of Hif1α protein on colonic mucosa sections from mice treated with no DSS, 7 days of DSS, and 7 days of DSS plus a 14-day recovery phase. Arrowheads denote the nuclear expression of Hif1α in epithelial cells of homeostatic (S), atrophic (T), and hypertrophic crypts (U).

Two-tailed Student’s t test: ^∗p < 0.05; ^∗∗p < 0.01. Bars: (N–P) 25 μm; (U) 50 μm; (inset of U) 10 μm. Histological and immune-staining images are representative of 3 Transwell samples or animals examined.

See also Figure S5.