In line with previous reports, the expression of both IL-17A and IL-22 is induced robustly by DSS treatment in wild-type mice; however, no significant differences in the expression of these cytokines was found between DSS-treated

wild-type and Bcl-3−/− mice (Fig. 4b). We next analysed the cellular composition of the leucocyte infiltrates in DSS-treated wild-type and Bcl-3−/− mice using immunofluorescence microscopy and antibodies against the cell surface markers F4/80 (macrophage), CD3 (T Cell), Ly6G (neutrophil) and CD11c (dendritic cells) Erlotinib purchase (Fig. 5a). Quantitative analysis of tissue sections demonstrated recruitment of macrophage, neutrophils and, to a lesser degree, T cells and dendritic cells to the distal colon of DSS-treated mice. No significant differences in the recruitment of these cell types were found between wild-type and Bcl-3−/−

mice (Fig. 5b). These data demonstrate that the inflammatory component of DSS-induced colitis is similar between wild-type and Bcl-3−/− mice and suggest that the reduced susceptibility of Bcl-3−/− mice may result from altered epithelial responses to treatment. Because DSS induces epithelial cell damage to initiate colonic inflammation and colitis we next measured cell death in the colon of wild-type and Bcl-3−/− mice using terminal dUTP nick end labelling (TUNEL) of tissue sections followed by fluorescence microscopy analysis. In both untreated wild-type and untreated Bcl-3−/− INCB018424 mouse mice we observed a small number of TUNEL-positive nuclei in the top of the crypt representing the normal turnover of epithelial cells in this tissue (Fig. 6a). However, following DSS treatment we observed a dramatic increase in TUNEL-positive cells in both wild-type and Bcl-3−/− mice. Quantitative analysis of TUNEL staining demonstrated no significant differences in the number Atezolizumab chemical structure of cells undergoing apoptosis in both groups. Immunoblot analysis of caspase-3 cleavage in colonic tissues also demonstrated a significant increase

in DSS-induced apoptosis in wild-type and Bcl-3−/− mice following DSS treatment (Fig. 6b). Densitometric analysis of cleaved caspase-3 levels normalized to β-actin levels revealed no significant difference between wild-type and Bcl-3−/− mice (Supporting Information, Fig. S2). Analysis of the mRNA levels of the apoptotic regulators p53 up-regulated modulator of apoptosis (PUMA), Bcl-XL, cellular inhibitor of apoptosis protein 1/2 (cIAP1/2) and phorbol-12-myristate-13-acetate-induced (NOXA) by qRT–PCR also revealed no significant differences expression between wild-type and Bcl-3−/− mice (Fig. 6c). We next assessed epithelial cell proliferation in tissue sections using the cell proliferation marker Ki67.