Figure 2.

Hypoxia inducible factor‐1α (HIF‐1α) promotes interleukin (IL)−33 expression in inflamed colon of mice with dextran sulphate sodium (DSS)‐induced colitis. (a) Six to 8‐week‐old C57BL/B6 mice (10 mice per group) were given 2% DSS in drinking water for 7 days, and switched to drinking water for an additional 3 days. Haematoxylin and eosin (H&E) staining in colonic tissues from wild‐type (WT) and DSS‐treated mice. (b−e) Quantitative real‐time–polymerase chain reaction (qRT–PCR) analysis for tumour necrosis factor (TNF), HIF‐1α, IL‐33 and vascular endothelial growth factor (VEGF) in colonic tissues of WT and DSS‐treated mice. Glyceraldehyde‐3‐phosphate dehydrogenase (GAPDH) was used as a housekeeping gene. ^* P < 0·05 versus wild‐type (WT) mice. (f) A positive correlation between HIF‐1α and IL‐33 in isolated intestinal epithelial cells (IECs) from colonic tissues of DSS‐treated mice (Pearson's correlation coefficient, R = 0·8108, P < 0·01). Data are plotted as relative expression of HIF‐1α and IL‐33 mRNA (n = 10 mice per group). [Colour figure can be viewed at wileyonlinelibrary.com]