Aims: The feasibility of using nanoparticles derived from Glycyrrhizae radix extract (Glycyrrhiza NPs) as a vaccine adjuvant for cancer immunotherapy was evaluated. Methods: C57BL/6J mice were immunized with ovalbumin (OVA) and Glycyrrhiza NPs. After immunization, splenocytes were incubated with the H-2Kb epitope peptide of OVA (SL8) and the production of IFN-γ was evaluated. Moreover, an OVA-expressing lymphoma cell line (E.G7-OVA cells) was inoculated into mice after immunization to evaluate the antitumor effect. Results: The immunization of OVA with Glycyrrhiza NPs induced IFN-γ production and completely rejected E.G7-OVA cells. Conclusion: Glycyrrhiza NPs could prime antigen-specific CD8+ T-cells resulting in antitumor effects. Therefore, Glycyrrhiza NPs can be an effective vaccine adjuvant for cancer immunotherapy.
Keywords: Glycyrrhiza; herbal medicine; immunotherapy; nanoparticles; vaccine adjuvant.
Glycyrrhizae radix is a medical plant that contains anti-inflammatory compounds such as glycyrrhizin. Nanoparticles (NPs) derived from Glycyrrhizae radix extract induced the production of proinflammatory cytokines. Therefore, these NPs could be used as a vaccine adjuvant. Here, a feasibility study on the use of Glycyrrhiza NPs as a vaccine adjuvant in cancer immunotherapy is reported. T-cell responses and antitumor effects were evaluated after the immunization of ovalbumin (OVA) with Glycyrrhiza NPs. The immunization of OVA with Glycyrrhiza NPs effectively induced OVA-specific T-cells and completely rejected OVA-expressing tumor cells. Therefore, Glycyrrhiza NPs could induce antitumor immunity and be an effective vaccine adjuvant in cancer immunotherapy.