Identification of a novel vaccine adjuvant that stimulates and maintains diphtheria toxoid immunity

Japanese Kampo medicine ninjin'yoeito synergistically enhances tumor vaccine effects mediated by CD8+ T cells

Although Japanese traditional herbal medicine (Kampo) has been widely applied to the treatment of various diseases, including cancer, their mechanisms of action have not yet been elucidated in detail, particularly regarding their role in tumor immunology. The present study investigated the antitumor effects of the Japanese Kampo medicine, ninjin'yoeito (NYT; Ren-Shen-Yang-Rong-Tang in Chinese), which was orally administered with or without an irradiated tumor cell vaccine to a subcutaneous CT26 colon carcinoma tumor model. The irradiated tumor cell vaccine in a prophylactic setting significantly delayed tumor growth in mice fed a control diet, whereas a diet containing NYT alone did not exert any antitumor effects in vivo. However, the inhibition of tumor growth was significantly greater in vaccinated mice fed the NYT diet compared with in vaccinated mice given the control diet. These results suggest that NYT synergistically enhances the effects of the antitumor vaccine. The depletion of cluster of differentiation (CD)8⁺ T cells abrogated these effects, indicating that antitumor activity required CD8⁺ T cells. Furthermore, reductions in CD4⁺ CD25⁺ and forkhead box protein 3⁺ T regulatory cell numbers were more apparent between vaccinated mice fed the NYT diet and non-vaccinated mice fed the control diet than between vaccinated mice and non-vaccinated mice fed the control diet, suggesting that the weaker impact of T regulatory cells contributes to the augmentation of antitumor immunity by CD8⁺ T cells in vaccinated mice fed with NYT. Overall, these results indicate that NYT synergistically enhances the effects of the prophylactic tumor vaccine mediated by CD8⁺ T cells and that this Japanese Kampo medicine has potential as a useful adjuvant agent for cancer immunotherapy.

Rehmannia glutinosa polysaccharide induces maturation of murine bone marrow derived Dendritic cells (BMDCs)

Purified Rehmannia glutinosa polysaccharide (RGP) is used as functional foods for the prevention and treatment of various diseases. In this study, we examined the effects of RGP on phenotypic and functional maturation of murine bone marrow derived Dendritic cells (BMDCs). Phenotypic maturation of BMDCs was confirmed by conventional scanning electron microscopy (SEM), flow cytometry (FCM) and functional maturation by transmission electron microscopy (TEM), cytochemistry assay, Acid phosphatase (ACP) activity, FITC-dextran, bio-assay and enzyme linked immunosorbent assay (ELISA).We found that RGP up-regulated the expression of CD40, CD80, CD83, CD86 and MHC II molecules of BMDCs, down-regulated pinocytosis and phagocytosis activity, induced IL-12 and TNF-α production of BMDCs. It is therefore concluded that RGP can effectively promote the maturation of DCs. Our study provides evidence and rationale on using RGP in various clinical conditions to enhance host immunity and suggests RGP as a potent adjuvant for the design of DC-based vaccines.

In planta production of plant-derived and non-plant-derived adjuvants

Recombinant antigen production in plants is a safe and economically sound strategy for vaccine development, particularly for oral/mucosal vaccination, but subunit vaccines usually suffer from weak immunogenicity and require adjuvants that escort the antigens, target them to relevant sites and/or activate antigen-presenting cells for elicitation of protective immunity. Genetic fusions of antigens with bacterial adjuvants as the B subunit of the cholera toxin have been successful in inducing protective immunity of plant-made vaccines. In addition, several plant compounds, mainly plant defensive molecules as lectins and saponins, have shown strong adjuvant activities. The molecular diversity of the plant kingdom offers a vast source of non-bacterial compounds with adjuvant activity, which can be assayed in emerging plant manufacturing systems for the design of new plant vaccine formulations.