To address the role of Tpl2, a MAP3K8 that regulates innate/ adaptive immunity and inflammation, in intestinal tumorigenesis, we crossed a Tpl2 KO allele into the Apcmin/+ genetic background. Here, we show that Apcmin/+/Tpl2-/- mice exhibit a fivefold increase in the number of intestinal adenomas. Bone marrowtransplantation experiments revealed that the enhancement of polyposis was partially hematopoietic cell-driven. Consistent with this observation, Tpl2 ablation promoted intestinal inflammation. IL-10 levels and regulatory T-cell numbers were lower in the intestines of Tpl2-/-mice, independent of Apc and polyp status, suggesting that they were responsible for the initiation of the enhancement of tumori-genesis caused by the ablation of Tpl2. The low IL-10 levels correlated with defects in mTOR activation and Stat3 phosphorylation in Toll-like receptor-stimulated macrophages and with a defect in inducible regulatory T-cell generation and function. Both polyp numbers and inflammation increased progressively with time. The rate of increase of both, however, was more rapid in Apcmin/+/Tpl2-/-mice, suggesting that the positive feedback initiated by inflammatory signals originating in developing polyps is more robust in these mice. This may be because these mice have a higher intestinal polyp burden as a result of the enhancement of tumor initiation.
|Original language||English (US)|
|Journal||Proceedings of the National Academy of Sciences of the United States of America|
|State||Published - May 1 2012|
- Inflammatory bowel disease
- Th17 cells
- Tr1 cells
ASJC Scopus subject areas