Abstract 4633: Crosstalk between MDSCs and Th17

Abstract

Abstract Expansion of myeloid-derived suppressor cells (MDSCs) within the tumor is a known barrier to successful cancer immunotherapy. MDSCs are heterogeneous population of immature myeloid cells with potent immunosuppressive activity. Emerging evidences in the recent years define the role of immunosuppressive activity of MDSCs on different subsets of CD4+ T cells, however the exact effect of MDSCs on inflammatory Th17 cells during tumor progression is not clear. Here we demonstrate the immunosuppressive effect of MDSCs on Th17 cells. We further show that the interaction between MDSCs and Th17 is not unilateral and reveal that Th17 cells can promote the immunosuppressive effect of MDSCs. MDSCs, either isolated from tumor bearing mice or generated in vitro from bone marrow (BM-derived MDSCs), can both suppress IL-17A expression. Our data also demonstrate that IFNg, produced by Th17 cells is essential for the immunosuppressive activity of BM-derived MDSCs on IL-17A expression and further that the IFNgR1-driven signaling is important for Nos2-mediated immunosuppressive effect of BM-derived MDSCs on IL-17A expression. Understanding the molecular mechanism of the interplay between MDSCs and Th17 cells may help to develop more specific targeted therapy for cancer immunotherapy and improve therapeutic efficacy of the existing therapies against cancer. Note: This abstract was not presented at the meeting. Citation Format: Brijendra Singh. Crosstalk between MDSCs and Th17 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4633. doi:10.1158/1538-7445.AM2017-4633