PPARγ-activation increases intestinal M1 macrophages and mitigates formation of serrated adenomas in mutant mice.

To identify novel hubs for cancer immunotherapy, we generated J mice with concomitant deletion of the drugable transcription factor PPARγ and transgenic overexpression of the mutant oncogene in enterocytes. Animals developed epithelial hyperplasia, transmural inflammation and serrated adenomas in the small intestine with infiltration of CD3+ FOXP3+ T-cells and macrophages into the lamina propria of the non-malignant mucosa. Within serrated polyps, CD3+ CD8+ T-cells and phosphorylated ERK1/2 were reduced and the senescence marker P21 and macrophage counts up-regulated, indicative of an immunosuppressive tissue microenvironment.