Immunopharmacological and immunotoxicological activities of a water-soluble (1-->3)-beta-D-glucan, CSBG from Candida spp

Chemistry and biology of angiitis inducer, Candida albicans water-soluble mannoprotein-beta-glucan complex (CAWS)

Deep mycoses have been clearly demonstrated to release beta-glucans into the blood. Structure of the beta-glucan was, at least in part, suggested to be a mannoprotein beta-glucan complex (CAWS) as assessed by biochemical and immunochemical analyses of the extracellular macromolecular fraction of Candida albicans. Half clearance time of i.v. administered CAWS was about 30 min in mice. In addition to the reactivity with limulus G-test, CAWS was found to exhibit various biological activities, such as cytokine synthesis by leukocyte, platelet aggregation, lethal toxicity, enhancement of side effect of indomethacin, induction of coronary arteritis in mice, and so on. In this review, the chemical properties and biological activities of CAWS are discussed.

Structure and biological activities of beta-glucans from yeast and mycelial forms of Candida albicans

We have achieved the extraction of cell wall beta-glucan from the mycelial form of Candida albicans (C. albicans) IFO 0579 (M-CSBG) by using acetic acid, sodium hypochlorite (NaClO), and dimethylsulfoxide (DMSO) treatments. The yield of M-CSBG was significantly lower (7.5% from dried mycelial cells) than that of the yeast form from C. albicans IFO 1385 (Y-CSBG, 25.9% from dried yeast cells). The properties of M-CSBG were similar to those of Y-CSBG in terms of nuclear magnetic resonance (NMR) spectra and limulus reactivity. Molecular weight (Mw) of M-CSBG was slightly higher than that of Y-CSBG. Both Y-CSBG and M-CSBG induced the production of comparable amounts of macrophage inflammatory protein-2 (MIP-2), a chemotactic factor, from mouse peritoneal exudate cells (PEC) in vitro. These findings suggest that the structure and properties of CSBG from yeast and mycelial cells are similar to each other.

Saccharomyces cerevisiae- and Candida albicans-derived mannan induced production of tumor necrosis factor alpha by human monocytes in a CD14- and Toll-like receptor 4-dependent manner

The cytokine-inducing activities of fungal polysaccharides were examined in human monocytes in culture, with special reference to CD14 and Toll-like receptors (TLRs). Tumor necrosis factor alpha (TNF-alpha) production by monocytes was markedly induced in a dose-dependent manner upon stimulation with cell walls from Candida albicans and mannan from Saccharomyces cerevisiae and C. albicans, although relatively high concentrations (10 to 100 microg/ml) of stimulants were required for activation as compared with the reference lipopolysaccharide (LPS) (1 to 10 ng/ml). The yeast form C. albicans and its mannan and cell wall fractions exhibited higher TNF-alpha production than respective preparations from the hyphal form. Only slight TNF-alpha production was induced by the S. cerevisiae glucan. The TNF-alpha production triggered by reference LPS and purified fungal mannans required the presence of LPS-binding protein (LBP), and these responses were inhibited by anti-CD14 and anti-TLR4 antibodies, but not by anti-TLR2 antibody. In contrast to the activity of LPS, the activity of purified S. cerevisiae mannan was not inhibited by polymyxin B. These findings suggested that the mannan-LBP complex is recognized by CD14 on monocytes and that signaling through TLR4 leads to the production of proinflammatory cytokines in a manner similar to that induced by LPS.

IFN-gamma induction by SCG, 1,3-beta-D-glucan from Sparassis crispa, in DBA/2 mice in vitro

Sparassis crispa Fr. in an edible mushroom recently cultivable in Japan. A branched beta-glucan from S. crispa (SCG) is a major 6-branched 1,3-beta-D-glucan showing antitumor activity. In this study, we examined interferon-gamma (IFN-gamma) induction by SCG from splenocytes in DBA/2 mice in vitro. In the splenocytes derived from almost all inbred strains of mice except for DBA/1 and DBA/2 mice, IFN-gamma production was not induced by SCG. The breeder and genders of DBA/2 mice showed no influence on IFN-gamma induction by SCG. On the other hand, the magnitude of IFN-gamma induction was lower in young mice than in their older counterparts. IFN-gamma was induced by SCG in adherent splenocytes, but IFN-gamma production was most significantly increased by SCG in instances involving coexistence of adherent and nonadherent splenocytes. In fact, inhibition of cell-cell contact reduced IFN-gamma induction by SCG. In addition, interleukin-12 p70 (IL-12p70) was induced by SCG in DBA/2 mice. It was suggested that soluble factors and cell-cell contact mediate synergistic effects on SCG-induced IFN-gamma production.

Maturation of dendritic cells induced by Candida beta-D-glucan

We investigated whether Candida beta-D-glucan (CSBG) alters the maturation of dendritic cells (DCs). DC phenotypes were analyzed using FACScan. The expression of surface molecules, including major histocompatibility complex (MHC) classes I and II, as well as CD80 and CD86, increased on DCs that were stimulated with lipopolysaccaride (DCs/LPS), in comparison with unstimulated bone marrow-derived DCs (BM-DCs). Furthermore, the level of surface molecule expression on DCs stimulated with CSBG (DCs/CSBG) was between that of DCs and DCs/LPS. Phagocytosis was assessed by the uptake of FITC-dextran. There were no differences in the uptake of dextran among DCs/LPS and DCs/CSBG. The ability of BM-DCs to uptake dextran was higher than that of DCs/LPS and DCs/CSBG. We analyzed the concentration of IL-12 secreted by DCs using ELISA. BM-DCs secreted a low concentration of IL-12, while DCs/LPS and DCs/CSBG secreted higher levels of IL-12 than BM-DCs. There were no remarkable differences in the concentrations of IL-12 produced by DCs/LPS and DCs/CSBG. This data suggests that CSBG may augment DC maturation.

Effect of SCG, 1,3-beta-D-glucan from Sparassis crispa on the hematopoietic response in cyclophosphamide induced leukopenic mice

Sparassis crispa Fr. is an edible mushroom recently cultivable in Japan. It contains a remarkably high content of 6-branched 1,3-beta-D-glucan showing antitumor activity. Using ion-exchange chromatography, a purified beta-glucan preparation, SCG, was prepared. In this study, we examined the hematopoietic response by SCG in cyclophosphamide (CY)-induced leukopenic mice. SCG enhanced the hematopoietic response in CY induced leukopenic mice by intraperitoneal routes over a wide range of concentrations. SCG enhanced the hematopoietic response in CY-treated mice by prior or post administration. Analyzing the leukocyte population by flow cytometry, monocytes and granulocytes in the peritoneal cavity, liver, spleen and bone marrow (BM) recovered faster than in the control group. The ratio of natural killer cells and gammadelta T cells in the liver, spleen and peritoneal cavity was also increased. In contrast, CD4+ CD8+ cells in the thymus were temporarily significantly decreased by the administration of SCG. Interleukin-6 (IL-6) production of CY+SCG-treated peritoneal exdated cells (PECs), spleen cells and bone marrow cells (BMCs) were higher than that of the CY-treated group. By in vitro culture of CY-treated PEC and spleen cells, IL-6 production was enhanced by the addition of SCG. These facts suggested the possibility that IL-6 might be a key cytokine for the enhanced hematopoietic response by SCG.

Relationship between the physical properties of Candida albicans cell well beta-glucan and activation of leukocytes in vitro

We previously reported that the fungal particle 1,3-beta-D-glucan derived from Candida albicans, a pathogenic fungus, was obtained by oxidation of the cell wall with sodium hypochlorite (NaClO). It could be solubilized by treatment with dimethylsulfoxide (DMSO). In the present study, we prepared Candida 1,3-beta-D-glucan having different physical properties, and examined the relationship between leukocyte activation and the physicochemical properties. Beta-glucan activated leukocytes significantly more effectively in a particulate than solubilized form in terms of TNF-alpha production by RAW 264.7 cells, hydrogen peroxide production by murine PEC and IL-8 production by human PBMC. Furthermore, we compared the biological activity of the glucan particles oxidized under various conditions. Interestingly, inactive and antagonistic particles were obtained under strong oxidation conditions. However, the inactive particles showed significant agonistic activity on dissolution in DMSO and following lyophilization. These facts strongly suggested that the solubility and assembly of the components influence the immunopharmacological activities of 1,3-beta-D-glucans.

Induction of interleukin-12 and gamma interferon requires tumor necrosis factor alpha for protective T1-cell-mediated immunity to pulmonary Cryptococcus neoformans infection

The development of T1-cell-mediated immunity is required to clear a pulmonary Cryptococcus neoformans infection. The objective of these studies was to determine the mechanism by which tumor necrosis factor alpha (TNF-alpha) augments the development of pulmonary T1 immunity to C. neoformans infection. TNF-alpha expression was detected in lavage sample cells at days 2, 3, and 7 following C. neoformans infection. The numbers of CFU in the lung were not different between control and anti-TNF-alpha-treated mice at any time point examined during the afferent phase of the response (days 0 to 7). However, neutralization of TNF-alpha prevented the initiation of pulmonary clearance during the efferent phase of the response (day 14). Administration of anti-TNF-alpha monoclonal antibody (day 0) diminished the lung levels of TNF-alpha, interleukin-12 (IL-12), and gamma interferon (IFN-gamma) induced by C. neoformans at day 7 postinfection. Neutralization of TNF-alpha (day 0) also altered the IFN-gamma/IL-4 ratio in the lung-associated lymph nodes at day 7 following C. neoformans infection. Anti-TNF-alpha-treated mice developed a pulmonary eosinophilia at day 14 postinfection. Consistent with the pulmonary eosinophilia, anti-TNF-alpha-treated mice exhibited elevated serum immunoglobulin E and inhibition of the anticryptococcal delayed-type hypersensitivity response, indicating a shift toward a T2 response. Neutralization of IL-12 also prevented lung leukocyte production of IFN-gamma in response to the infection. These findings demonstrate that afferent-phase TNF-alpha production is essential for the induction of IL-12 and IFN-gamma and neutralization of early TNF-alpha results in a T2 shift of the T1/T2 balance of antifungal immunity.

The pathogenetic significance of intestinal Candida colonization--a systematic review from an interdisciplinary and environmental medical point of view

The etiological significance of intestinal Candida colonization continues to be controversial. This is a systematic review to determine the pathogenetic significance of intestinal Candida colonization. The search was essentially performed from 1990 to 12/7/2000 in Medline and the Cochrane-Library. The data source was restricted to articles in English and German. Selection criteria covered the topics "Epidemiology", "Infectious Diseases", "Candida-Syndrome" and "Therapy" and were essentially confined to in-vivo examination of immunocompetent adults. Two reviewers extracted independently data using predefined criteria. In total, 96 citations that proved suitable for use in the systematic review were found. Depending on the localization in the gastrointestinal tract, the recovery technique employed, and transport times, Candida colonization is frequently detected in healthy, immunocompetent adults (prevalence: 4-88%). None of the studies available so far furnish any evidence that nutritional factors, food additives, pollutants, anti-ovulants, other types of medication or diabetes mellitus might be predisposing factors for intestinal Candida colonization. However, therapeutic studies point to the possibility of Candida playing a role in antibiotic-associated diarrhea. On the other hand, antibiotics seem to favor bacterial dysbiosis, and this, like the direct side effects of drugs, offers a more plausible explanation for diarrhea or gastrointestinal symptoms. The role of intestinal colonization by Candida in Candida-associated vulvovaginitis and IgE-mediated disorders remains contradictory. Nevertheless, neither epidemiological nor therapeutic studies provide evidence for the existence of the so-called "Candida-syndrome" or "Candida-hypersensitivity-syndrome". At present, there are no proven treatment indications for antifungal "bowel decontamination".

Effect of a soluble alpha-D-glucan from the lichenized fungus Ramalina celastri on macrophage activity

An alpha-glucan from the lichen Ramalina celastri has previously been demonstrated to have cytotoxic effects against HeLa cells. This polysaccharide was studied using Sarcoma-180 cells as tumoral model, and its effects on peritoneal exudate cells, namely, hydrogen peroxide production, phagocytic activity and cell eliciting activity are evaluated. Tumors developing in animals treated with the glucan at a dose of 200 mg kg(-1), had a tumor size approximately 80% smaller than that of the control group, showing an impairment of tumor establishment. The polysaccharide was injected into mice not bearing a tumor and after 7, 15 and 30 days the cells were collected from the peritonea. The number of peritoneal cells increased approximately 130% 7 days after inoculation, and then gradually decreased. Hydrogen peroxide production was 75% greater 7 and 15 days after inoculation, on in vitro phorbol myristate acetate (PMA) triggering. Without PMA, the difference in hydrogen peroxide production was not significant. Phagocytic assays using fluorescent beads showed that the uptake increased 7 and 15 days after inoculation, when compared with the control. These results thus suggest a possible role of the R. celastri glucan as a biological response modifier (BRM).

Application of Candida solubilized cell wall beta-glucan in antitumor immunotherapy against P815 mastocytoma in mice

This study was designed to evaluate the antitumor activity of CSBG, purified from the cell wall of Candida albicans IFO1385. First, as an effect of CSBG on P815 mastocytoma, significant prolonged survival and suppression of the tumor growth were observed. Second, the transfer of spleen cells from CSBG-sensitized BALB/c mice to CDF1 mice led to further suppression of tumor growth as well as P815-immunized spleen cells. Third, CSBG enhanced antitumor immunity in gene therapy using B7-1-transfected P815 cells. These results strongly suggest that CSBG enhances the host defense response to tumor due in part to an adjuvant effect.

Contribution of myeloperoxidase to coronary artery vasculitis associated with MPO-ANCA production

The role of myeloperoxidase (MPO) in the pathogenesis of vasculitis associated with MPO-specific anti-neutrophil cytoplasmic autoantibody (MPO-ANCA) was examined in a murine animal model. Coronary artery vasculitis was induced in C57BL/6 mice with and without endogenous MPO by intraperitoneal injection of Candida albicans-derived substances (CADS). The corresponding levels of MPO-ANCA in sera of mice with and without vasculitis were measured and compared in both wild-type and MPO-deficient animals. The MPO-ANCA titers in sera were significantly higher in mice with vasculitis than in vasculitis-negative mice, indicating that MPO-ANCA correlated with vasculitis formation. However, the increase of MPO-ANCA titers observed in sera of wild C57BL/6 mice were strongly suppressed in MPO-deficient C57BL/6 mice, accompanied with prevention of vasculitis formation. These results show that MPO acted as an antigen for MPO-ANCA production by CADS and was followed by the vasculitis formation. Vasculitis did develop in a few MPO-deficient mice, though the incidence of vasculitis was much lower in MPO-deficient mice than in C57BL/6 mice.