Glycyrrhiza uralensis polysaccharides as a DC-based Vaccine Adjuvant: Enhanced Immunotherapy Combined with PD-1 Blockade

The activation of naive CD8 ⁺ T cells by mature dendritic cells (DCs) through antigen presentation is essential for initiating effective anti-tumor immunity. In our previous study, Glycyrrhiza uralensis polysaccharides (GUPS) were prepared and found that they significantly promoted the maturation and cytokine secretion of human Mo-DC and murine BM-DC through TLR4 signaling pathways. In this study, HPV-DC vaccine prepared with GUPS (GUPS-DC + HPV) significantly suppressed the tumor growth and improved the survival of tumor mice, which was correlated with the induction of HPV-16-specific cellular response and the increased infiltration of CD8 ⁺ T cells in tumors. Although HPV-DC vaccine can induce CTL response and inhibit tumor growth, the late treatment effect needs to be further improved. Therefore, the combination treatment of HPV-DC vaccine and anti-PD-1 Ab could further improve the therapeutic efficacy, improve the survival rate of tumor mice, generated memory immune response and suppressed lung metastasis of tumors. These findings suggest GUPS as a potent adjuvant that promotes DC maturation, and offering a combination strategy for the treatment of advanced tumors.