Co-loaded simvastatin-ginsenoside Rh2 liposomes enhance cellular immune responses as vaccine adjuvants

Vaccine adjuvants are pivotal in novel vaccine development, enhancing immunization and modulating immune responses. This study prepared liposomes loaded with simvastatin and ginsenoside Rh2 (LIPO-SIM-Rh2) via high-speed shearing, rotary evaporation, and high-pressure homogenization. Using C57BL/6J mice, six groups were established to explore its immune-enhancing effects and mechanisms. Following two-dose immunization at 0 and 21 days, IgG antibody titers (ELISA), immune cell responses (flow cytometry), and safety/function of antigen-presenting cells (pathological sections, immunofluorescence staining) were detected. Results showed LIPO-SIM-Rh2 had a stable dispersion and a near-100 % encapsulation efficiency. Compared with other groups, it significantly increased anti-OVA specific IgG titer, promoted cellular immune response, up-regulated MHC-I molecule antigen presentation pathway, activated macrophages, promoted dendritic cell homing, and caused no obvious damage or inflammation to major organs. In conclusion, LIPO-SIM-Rh2 adjuvant has a feasible preparation method and strong immune-enhancing potential for vaccines.