Extracts of Larix Leptolepis effectively augments the generation of tumor antigen-specific cytotoxic T lymphocytes via activation of dendritic cells in TLR-2 and TLR-4-dependent manner.

Type-1 immunity plays a crucial role in host defense against various tumors and infectious diseases. Here, we first demonstrated that extract of Larix Leptolepis (ELL), one of the most popular timbers at Hokkaido area in Japan, strongly activated Type-1 immunity. ELL induced production of Type-1 cytokines such as IL-12 and TNF-α from bone marrow-derived dendritic cells (BMDCs) in TLR2- and TLR4-dependent manner and remarkably up-regulated the expression of MHC and co-stimulatory molecules. In addition, antigen-specific CTLs were significantly augmented by the combined administration of ELL, antigen and BMDCs. Finally, we revealed that combination therapy using ELL, antigen and BMDCs significantly inhibited the growth of established tumor in mouse model. Thus, these findings suggested that ELL would be a novel adjuvant for inducing an activation of Type-1-dependent immunity including activation of BMDCs and induction of tumor-specific CTLs, which is applicable to the therapy of cancer and infectious diseases.

Toll-like receptor-dependent IL-12 production by dendritic cells is required for activation of natural killer cell-mediated Type-1 immunity induced by Chrysanthemum coronarium L.

Type-1 immunity has an essential role for our host defenses against cancer and outer pathogens such as bacteria and virus. We demonstrated here that the edible plant extract of Chrysanthemum coronarium L. (C. coronarium) remarkably activates Type-1 immunity in a Toll-like receptor (TLR)2-, TLR4-, and TLR9-dependent manner. In the present experiments, the extract of C. coronarium significantly induces interferon (IFN)-γ production by mouse spleen cells. In addition, the IFN-γ production by spleen cells was completely blocked by the addition of anti-Interleukin (IL)-12 monoclonal antibodies. We confirmed that NK1.1(+) natural killer (NK) cells, NKT cells, and CD11c(+) dendritic cells (DC) were immediately activated after the stimulation with the extract of C. coronarium and the IFN-γ production was abolished in NK1.1(+) cell-depleted spleen cells. The stimulation with the extract of C. coronarium caused DC maturation involving with up-regulations of surface expression levels of MHC class I, MHC class II, CD40, and CD86 as well as induction of IL-12 production. The IFN-γ production induced by the extract was significantly reduced in the spleen cells depleted CD11c(+) cells. Furthermore, the IFN-γ production after the stimulation was strongly reduced in TLR4- and partially in TLR2- and TLR9-deficient spleen cells. Thus, we demonstrated the cellular mechanism for the activation of Type-1 immunity via NK cells, NKT cells, and DC by the extract of C. coronarium. These findings strongly suggest that C. coronarium would be a promising immuno-improving adjuvant, which might be useful for prevention of infectious, cancer, and allergic diseases through the activation of Type-1 immunity.

The extract of Japanese soybean, Kurosengoku activates the production of IL-12 and IFN-γ by DC or NK1.1(+) cells in a TLR4- and TLR2-dependent manner.

During the search for immuno-improving foods, we found that a variety of the Japanese soybean, Glycine max cv. Kurosengoku (Kurosengoku), which activated Type-1 immunity in a Toll-like receptor (TLR)4- and TLR2-dependent manner. Namely, the extract of Kurosengoku first caused production of IL-12 from DC and sequentially induced IFN-γ production by NK1.1(+) NK cells and NKT cells. The IFN-γ production was significantly blocked by neutralizing mAb against IL-12 or TLR4- and TLR2-deficient condition, indicating that TLR4- and TLR2-dependent activation of DC to produce IL-12 was essential for the production of IFN-γ from spleen cells by Kurosengoku. Moreover, the extract of Kurosengoku also enhanced production of IFN-γ from human PBMC by co-stimulation with anti-CD3 mAb in a TLR2- and TLR4-dependent manner. Thus, our findings strongly suggest that Kurosengoku might a novel immuno-improving food, which would be a useful tool for preventing the tip of immune balance in developed countries.

Toll-like receptor-mediated regulation of zinc homeostasis influences dendritic cell function.

Zinc is a trace element that is essential for the function of many enzymes and transcription factors. Zinc deficiency results in defects in innate and acquired immune responses. However, little is known about the mechanism(s) by which zinc affects immune cell function. Here we show that stimulation with the Toll-like receptor 4 agonist lipopolysaccharide (LPS) altered the expression of zinc transporters in dendritic cells and thereby decreased intracellular free zinc. A zinc chelator mimicked the effects of LPS, whereas zinc supplementation or overexpression of the gene encoding Zip6, a zinc transporter whose expression was reduced by LPS, inhibited LPS-induced upregulation of major histocompatibility complex class II and costimulatory molecules. These results establish a link between Toll-like receptor signaling and zinc homeostasis.