Abstract 1464: Inhibition of p38 MAPK in dendritic cells enhances their antigen presentation and induces Th17 T cell differentiation

Dendritic cells (DCs) are the most potent antigen-presenting cells which bridges innate and adaptive immunity, but how DC-derived signals regulate and induce T cell lineage choices remains unclear. The p38 MAPK pathway plays an essential role in regulating cellular processes such as cell differentiation, growth, and death. In this study, SB203580 was employed to selectively inhibit p38 pathway in bone marrow derived DCs (BMDCs) to investigate the effects of this pathway on the characteristic phenotype and function of DCs, especially the induction on T helper cell differentiation. We found that inhibition of p38 increased the proliferation of BMDCs, but did not alter their phagocytic ability. Also, inhibition of p38 enhanced the activation of BMDCs, as evidenced by the up-regulated expression of DCs-related surface markers including CD80, CD86 and MHCII. However, the secretion levels of IL-12 and IL-10 in BMDCs were reduced significantly, whereas the level of IL-6 was not influenced by the p38 inhibitor. In addition, we immunized the mice with BMDCs vaccines and studied the production of antigen-specific Th17 T cell in spleen. Our data demonstrated that p38-inhibited DCs vaccine could induce more antigen-specific Th17 T cells than regular DCs vaccine in vivo . Collectively, these results support the hypothesis that the p38 pathway plays a critical role in the immunologic activation of DCs. Our findings suggest that inhibition p38 pathway in DCs may be a new strategy for generating potent DC vaccines for cancer immunotherapy. Citation Format: Yan Luo, Shreeder Barath, Deborah A. Bahr, Navnita Dutta, Geraldine Raja, Martin J. Cannon, Keith L. Knutson. Inhibition of p38 MAPK in dendritic cells enhances their antigen presentation and induces Th17 T cell differentiation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1464.