Figure 7. IL-22 deficiency leads to increased epithelial damage and loss of intestinal stem cells.

LP→B6 BMT was performed with WT or Il22^−/− recipients and analyzed three weeks post-BMT. (A) Histopathologic assessment of apoptosis in crypt epithelium was performed on tissue sections from transplanted mice. Graph shows histopathologic apoptosis score for intestinal tissues from BMT recipients transplanted with or without T cells. Image shows representative TUNEL staining on serial sections from small intestine post-BMT, confirming apoptosis (black arrows) in crypt epithelium of Il22^−/− recipients during GVHD. (B) Histologic assessment of small intestine CBC cells was performed on tissue sections from WT and Il22^−/− recipients with (BM + T) or without (BM only) GVHD. Graph shows small intestine CBC frequencies in non-reporter mice without transplantation and post-BMT (C-D) Quantitative PCR for Reg3γ and Reg3β mRNA expression was performed on colon samples from WT vs. Il22^−/− recipients with GVHD. Graphs show Reg3γ and Reg3β relative expression in colons after BMT with marrow and T cells. (E) BMT recipients of marrow and T cells were challenged with oral gavage of FITC-dextran three weeks post-BMT. Graph shows plasma FITC-dextran concentrations in WT vs. Il22^−/− recipients with GVHD. Data are combined (A-E) or representative (TUNEL assay) of at least two independent experiments and at least eight mice per group; bar graphs show mean and standard error. *p<.05, **p<.01, ***p<.001.