Lymph nodes are the main sites for immune activation and surveillance. Effective delivery of immunomodulators into lymph nodes to trigger antitumor immunity is essential for cancer treatment. Here, we propose a lymph node delivery strategy to modulate the immune response by activating cytotoxic T lymphocytes (CTLs) and natural killer (NK) cells simultaneously. Novel pH/redox dual-sensitive micelles were prepared using poly(l-histidine)-poly(ethylene glycol) (PLH-PEG) as a skeleton, which can effectively deliver immunomodulators to the lymph nodes due to their suitable particle size. At 48 h after subcutaneous injection, the accumulation efficiency in lymph nodes increased 8.12-fold compared with the control group. Subsequently, Trp2/CpG-coloaded pH/redox dual-sensitive micelles (Trp2/CpG-NPs) acted on antigen-presenting cells, fully promoting CTL activation through dendritic cell antigen cross-presentation and macrophage repolarization. IL-15-loaded pH/redox dual-sensitive micelles (IL-15-NPs) were developed to activate the killing effect of NK cells by interacting with IL-15 receptors. In the tumor-bearing mice model, this lymph node delivery strategy showed significant antitumor efficiency and the tumor inhibition rate reached 93.76%. Meanwhile, the infiltration of CTLs and NK cells in tumor tissues increased, and the immunosuppressive microenvironment was relieved by the repolarization of macrophages from M2-type to M1-type. Overall, this study highlighted the potential of the lymph node delivery strategy for cancer immunotherapy.
Keywords: cancer immunotherapy; cancer vaccine; cytotoxic T lymphocytes; lymph nodes; natural killer cells.