Tumor promotion by intratumoral plasmacytoid dendritic cells is reversed by TLR7 ligand treatment - PubMed (original) (raw)

. 2013 Aug 1;73(15):4629-40.

doi: 10.1158/0008-5472.CAN-12-3058. Epub 2013 May 30.

Dominique Poujol, Amélien Sanlaville, Vanja Sisirak, Michael Gobert, Isabelle Durand, Bertrand Dubois, Isabelle Treilleux, Jacqueline Marvel, Jaromir Vlach, Jean-Yves Blay, Nathalie Bendriss-Vermare, Christophe Caux, Isabelle Puisieux, Nadège Goutagny

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Tumor promotion by intratumoral plasmacytoid dendritic cells is reversed by TLR7 ligand treatment

Isabelle Le Mercier et al. Cancer Res. 2013.

Abstract

Plasmacytoid dendritic cells (pDC) are key regulators of antiviral immunity. In previous studies, we reported that pDC-infiltrating human primary breast tumors represent an independent prognostic factor associated with poor outcome. To understand this negative impact of tumor-associated pDC (TApDC), we developed an orthotopic murine mammary tumor model that closely mimics the human pathology, including pDC and regulatory T cell (Treg) infiltration. We showed that TApDC are mostly immature and maintain their ability to internalize antigens in vivo and to activate CD4(+) T cells. Most importantly, TApDC were specifically altered for cytokine production in response to Toll-like receptor (TLR)-9 ligands in vitro while preserving unaltered response to TLR7 ligands (TLR7L). In vivo pDC depletion delayed tumor growth, showing that TApDC provide an immune-subversive environment, most likely through Treg activation, thus favoring tumor progression. However, in vivo intratumoral administration of TLR7L led to TApDC activation and displayed a potent curative effect. Depletion of pDC and type I IFN neutralization prevented TLR7L antitumoral effect. Our results establish a direct contribution of TApDC to primary breast tumor progression and rationalize the application of TLR7 ligands to restore TApDC activation in breast cancer. Cancer Res; 73(15); 4629-40. ©2013 AACR.

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