Oral administration of soluble ß-glucan preparation from the cauliflower mushroom, Sparassis crispa (Higher Basidiomycetes) modulated cytokine production in mice.

Soluble ß-glucan preparation from the cold NaOH extract of Sparassis crispa (SCG) is a six-branched 1,3-ß-D-glucan that is a major cell-wall structural component in fungi. Leukocytes from DBA/2 mice are highly sensitive to SCG, producing cytokines in vitro. We previously reported that the intraperitoneal (i.p.) administration of ß-glucan decreased cytokine induction by SCG in vitro in DBA/2 mice. In this study, we examined the effects of the oral (p.o.) administration of polysaccharide fractions extracted from S. crispa, using hot water (SCHWE), a ß-glucan from S. crispa, to DBA/2 mice on cytokine induction by SCG in the spleen in vitro. The level of induction of IFN-γ and GM-CSF by SCG was significantly increased in SCHWE-treated mice. This activity was more clearly observed when chlorpromazine was administered as a pretreatment in SCHWE-treated mice. The production of GM-CSF, IFN-γ, and IL-6 by immune cells in Peyer's patches was higher in SCHWE-treated mice than in control mice. These results suggest that orally administered ß-glucan may modulate cytokine induction by SCG in the spleen through the activation of Peyer's patches.

Disruption of actin cytoskeleton enhanced cytokine synthesis of splenocytes stimulated with beta-glucan from the cauliflower medicinal mushroom, Sparassis crispa Wulf.:Fr. (higher Basidiomycetes) in vitro.

Beta-glucan (BG) is a representative pathogen-associated molecular pattern (PAMP) produced by pathogenic fungi. SCG is a BG obtained from Sparassis crispa, which stimulates splenocytes in DBA/2 mice to produce cytokines, such as GM-CSF, IFN-γ, and TNF-α. In the present study, we analyzed the molecular mechanism of SCG-mediated cytokine synthesis using cytocharasin D (CytD), an inhibitor of actin polymerization. It was found that GM-CSF and TNF-α synthesis of splenocytes stimulated with SCG, but not with lipopolysaccharide, was significantly enhanced in the presence of CytD. CRDO, partially hydrolyzed linear 1,3-BG curdlan, stimulated splenocytes of DBA/2 mice slightly to produce cytokines. CRDO, acting as an antagonist in the presence of SCG, changed to a strong agonist in the presence of CytD. CytD also enhanced cytokine synthesis of bone marrow-derived dendritic cells. Taken together, cytokine productivity of BG was significantly dependent on molecular weight, and CytD treatment is useful to enhance the sensitivity for analyzing the immunostimulating activity of BG in vitro.

Effect of Sasa veitchii extract on immunostimulating activity of ß-glucan (SCG) from culinary-medicinal mushroom Sparassis crispa Wulf.:Fr. (higher Basidiomycetes).

Fungal ß-glucan is a representative pathogen-associated microbial pattern (PAMP) from mushroom, yeast, and fungi, and stimulates innate as well as acquired immune systems. It is a widely used functional food to enhance immunity. Such plant extracts have been known as folk medicines and reported to show various biological activities beneficial to human health, such as anti-tumor, anti-allergic, and anti-inflammatory activities. In the present study, the cooperative effect of bamboo water-soluble methanol precipitation (BWMP), a macromolecular fraction of the hot-water extract of Sasa veitchii (Japanese folk medicine Kumazasa), and the ß-glucan from the medicinal mushroom Sparassis crispa (SCG) was analyzed in vitro using DBA/2 mice. The splenocytes from male DBA/2 mice were cultured with BWMP in the presence of SCG, and the responses were assessed by measuring cytokines. BWMP suppressed IFN-γ and GM-CSF production by SCG, but not TNF-α production. To analyze the specificity of the reaction, similar experiments were conducted with BWMP in the presence of bacterial lipopolysaccharide (LPS); however, none of the cytokines were inhibited. Cytokine production of splenocytes by SCG was suggested to be largely dependent on the binding of lymphocytes with dendritic cells. Functions of BWMP were also analyzed by mixed lymphocyte reaction, and IFN-γ production was suppressed. These findings suggested that BWMP modulated the cell-to-cell contact induced by SCG and inhibited cytokine production. It is strongly suggested that the plant extracts modulate the immunostimulating effects of medicinal mushrooms. Cooperative effects of plants and mushrooms would be an important issue for functional foods.

Effect of GM-CSF on cytokine induction by soluble beta-glucan SCG in vitro in beta-glucan-treated mice.

SCG is a 6-branched 1,3-beta-D-glucan, which are major cell wall structural components in fungi. Leukocytes from DBA/1 and DBA/2 mice are highly sensitive to SCG, producing cytokines such as GM-CSF, IFN-gamma, TNF-alpha and IL-12p70, but not IL-6. GM-CSF plays a key biological role in this activity. In the present study, we examined the effect of giving i.p. SCG to DBA/2 mice on cytokine production in vitro. SCG was given i.p. to DBA/2 mice on day 0. Splenocytes were prepared on day 7 and cultured in the presence of SCG in vitro. The levels of cytokine production induced by SCG in vitro were lower in the cells from SCG-treated mice than in control mice. Expression of the beta-glucan receptor, dectin-1, in SCG-treated mice was comparable with that shown in control mice. However, the consumption of exogenously added rmGM-CSF in vitro was observed in SCG-treated mice. The addition of a large amount of rmGM-CSF to the culture medium resulted in larger amounts of TNF-alpha and IL-6 in SCG-treated mice than in normal mice. These results suggested that GM-CSF was closely related with the reactivity of beta-glucan. Giving SCG increased the number of macrophages and granulocytes in the spleen. These results suggested that in SCG-treated mice, a change of cell population would be related to modulation of the profile of cytokine production induced by SCG in vitro.