Specialized dendritic cells induce tumor-promoting IL-10<sup>+</sup>IL-17<sup>+</sup> FoxP3<sup>neg</sup> regulatory CD4<sup>+</sup> T cells in pancreatic carcinoma.

Barilla, Rocky M; Diskin, Brian; Caso, Raul Caso; Lee, Ki Buom; Mohan, Navyatha; Buttar, Chandan; Adam, Salma; Sekendiz, Zennur et al. · Nat Commun · 2019

basic_science · Level V

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Abstract

The drivers and the specification of CD4<sup>+</sup> T cell differentiation in the tumor microenvironment and their contributions to tumor immunity or tolerance are incompletely understood. Using models of pancreatic ductal adenocarcinoma (PDA), we show that a distinct subset of tumor-infiltrating dendritic cells (DC) promotes PDA growth by directing a unique T<sub>H</sub>-program. Specifically, CD11b<sup>+</sup>CD103<sup>-</sup> DC predominate in PDA, express high IL-23 and TGF-β, and induce FoxP3<sup>neg</sup> tumor-promoting IL-10<sup>+</sup>IL-17<sup>+</sup>IFNγ<sup>+ </sup>regulatory CD4<sup>+</sup> T cells. The balance between this distinctive T<sub>H</sub> program and canonical FoxP3<sup>+ </sup>T<sub>REGS</sub> is unaffected by pattern recognition receptor ligation and is modulated by DC expression of retinoic acid. This T<sub>H</sub>-signature is mimicked in human PDA where it is associated with immune-tolerance and diminished patient survival. Our data suggest that CD11b<sup>+</sup>CD103<sup>-</sup> DC promote CD4<sup>+</sup> T cell tolerance in PDA which may underscore its resistance to immunotherapy.

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