Tumor-derived extracellular vesicles regulate tumor-infiltrating regulatory T cells via the inhibitory immunoreceptor CD300a
Yuta Nakazawa,
Nanako Nishiyama,
Hitoshi Koizumi,
Kazumasa Kanemaru,
Chigusa Nakahashi-Oda,
Akira Shibuya
Affiliations
Yuta Nakazawa
Department of Immunology, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan; Doctoral Program of Biomedical Sciences, Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba, Japan
Nanako Nishiyama
Department of Immunology, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan; Doctoral Program of Biomedical Sciences, Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba, Japan
Hitoshi Koizumi
Department of Immunology, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan; Doctoral Program of Biomedical Sciences, Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba, Japan
Department of Immunology, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan; R&D Center for Innovative Drug Discovery, University of Tsukuba, Tsukuba, Japan
Department of Immunology, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan; R&D Center for Innovative Drug Discovery, University of Tsukuba, Tsukuba, Japan
Department of Immunology, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan; R&D Center for Innovative Drug Discovery, University of Tsukuba, Tsukuba, Japan; Life Science Center for Survival Dynamics, Tsukuba Advanced Research Alliance (TARA), University of Tsukuba, Tsukuba, Japan
Although tumor-infiltrating regulatory T (Treg) cells play a pivotal role in tumor immunity, how Treg cell activation are regulated in tumor microenvironments remains unclear. Here, we found that mice deficient in the inhibitory immunoreceptor CD300a on their dendritic cells (DCs) have increased numbers of Treg cells in tumors and greater tumor growth compared with wild-type mice after transplantation of B16 melanoma. Pharmacological impairment of extracellular vesicle (EV) release decreased Treg cell numbers in CD300a-deficient mice. Coculture of DCs with tumor-derived EV (TEV) induced the internalization of CD300a and the incorporation of EVs into endosomes, in which CD300a inhibited TEV-mediated TLR3–TRIF signaling for activation of the IFN-β-Treg cells axis. We also show that higher expression of CD300A was associated with decreased tumor-infiltrating Treg cells and longer survival time in patients with melanoma. Our findings reveal the role of TEV and CD300a on DCs in Treg cell activation in the tumor microenvironment.
