Figure 3
Hypo-osmotic stress induces IL-33 in colonic crypts. Colonic biopsies from ex vivo biopsy cultures including quiescent UC with a a Mayo score ≤ 2 (image A,E) and healthy controls (image B–D). Stimulation with hypo-osmotic medium for 24 h induces positive IL-33 (brown) cells shown with immunoenzymatic staining in (A–C). Cell nuclei stained with hematoxylin (blue). Control biopsy cultured for 24 h in basal medium (image D) did not show IL-33 positive cells in the epithelium. Image (E) shows fluorescence staining in UC after 24 h of hypo-osmotic basal medium, IL-33 (red) is seen in the nucleus of epithelial cells with cell nuclei counterstained with Hoechst (blue). IL-33 was significantly increased in the epithelium of both healthy controls (NC) with a p-value = 0.01 and for UC p-value = 0.04 following hypo-osmotic exposure for 24 h (graph F). No significant changes were seen in the stroma (graph G) p-values 0.14 and 0.38 for NC and UC. Graph (H) shows fold change of mucosal gene expression for IL33, ST2 and TNF comparing biopsies stimulated with hypo-osmotic medium or basal medium (controls) for 24 h. Scale bars = 20 µm.
