Growth-inhibitory effects of a beta-glucan from the mycelium of Poria cocos on human breast carcinoma MCF-7 cells: cell-cycle arrest and apoptosis induction

Because of the reported immune-enhancing and anti-tumor activities of some mushroom polysaccharides, their applications as biological response modifiers have attracted significant attention. We have purified a water-soluble beta-glucan PCM3-II, comprising mainly 1right curved arrow 3 and 1right curved arrow 4 linkages, from the mycelia of Poria cocos (Schw.) Wolf (Fu-ling). In this study, the growth-inhibitory effect of PCM3-II was further explored on the human breast carcinoma MCF-7 cells in vitro. The dose effect of PCM3-II was studied by incubating the breast cancer cells with 12.5-400 microg/ml of the glucan for 72 h. The MTT study showed that PCM3-II reduced proliferation and viability of the MCF-7 cells dose-dependently, so that the cancer-cell growth was decreased by 50% of the control level at 400 microg/ml of the glucan. The time effect of PCM3-II was then investigated by treating the breast cancer cells with 400 microg/ml of the glucan for 24, 48 and 72 h, respectively. Results from the flow cytometry study demonstrated that PCM3-II induced cell-cycle G1 arrest time-dependently and about 90% of the cells in cell cycle were accumulated at G1 phase after 72 h of treatment. The G1 arrest was associated with downregulations of the unscheduled cyclin D1 and cyclin E expressions in the breast cancer cells. Apoptosis was also induced by PCM3-II in the MCF-7 cells, so that the subG1 cells in DNA histogram of the flow cytometry were elevated by 5-fold of the control level at 48 h and by 24-fold at 72 h of treatment. The immunoblot study also showed that the glucan induced depletion of the antiapoptotic Bcl-2 protein, but not the proapoptotic Bax protein, so that the Bax/Bcl-2 ratio was elevated in the breast cancer cells at the time when the most prominent apoptosis was also observed. In conclusion, although the detailed mechanism for the anti-tumor activity of the P. cocos beta-glucan still needs further investigation, this study provides preliminary insights into its mode of action and perspectives of its development as a water-soluble anti-tumor agent.

Effect of multiple injections of beta-glucan on non-specific immune response and disease resistance in Labeo rohita fingerlings

The purpose of this study was to determine if multiple injections of different dosages of beta-glucan derived from barley would enhance the immune response and disease resistance against infections due to opportunistic pathogens Aeromonas hydrophila and Edwardsiella tarda in Labeo rohita fingerlings. Hence, four different dosages of beta-glucan suspension in phosphate-buffered saline at the rate of 0, 5, 10, 15 mg kg(-1) body weight of fish were injected intraperitoneally to the fingerlings of Labeo rohita at two-week intervals for four times. After every two-week interval different serum biochemical, haematological and immunological parameters of fish were evaluated. At the end of immunostimulation trial of 56 days, fish were divided into four subgroups under each major treatment group for challenge through i.p injection and bath immersion with two pathogens, A. hydrophila and E. tarda. The mortality (%) and agglutinating antibody titre was recoded on 28th day post challenge. Most of the immune parameters such as leucocyte count, phagocytic ratio, phagocytic index, lysozyme activity, complement activity, serum bactericidal activity were significantly (P < 0.05) enhanced on 42 days after three i.p injections of 10 mg of beta-glucan kg(-1) body wt. Challenge study indicated least mortality in the group of fishes injected with medium dose of 10 mg of beta-glucan kg(-1) body wt. four times. Multiple injections of beta-glucan might have maintained the activation of phagocytic cells for a long period which in turn would lead to long-term protection in fishes. Thus, injections of 10 mg of beta-glucan kg(-1) body wt. for three times can be advocated to enhance the immune response of fish species under aquaculture.

Coupling of C3bi to IgG inhibits the tyrosine phosphorylation signaling cascade downstream Syk and reduces cytokine induction in monocytes

The effect of coupling C3bi to immunoglobulin G (IgG) immune complexes (IC) on their ability to produce protein tyrosine phosphorylation and activation of the mitogen-activated protein kinase (MAPK) and the Akt/protein kinase B (PKB) routes was assessed in human monocytes. Cross-linking Fc receptors for IgG activated the protein tyrosine kinase Syk, phospholipases Cgamma1 and Cgamma2, the MAPK cascade, and the Akt/PKB route. Linkage of C3bi to the gamma-chain of IgG produced a decrease of the protein bands displaying tyrosine phosphorylation, whereas the MAPK cascades and the Akt/PKB route remained almost unaffected. Zymosan particles, which because of their beta-glucan content mimic the effect of fungi, produced a limited increase of tyrosine-phosphorylated protein bands, whereas treatment of zymosan under conditions adequate for C3bi coating increased its ability to induce protein tyrosine phosphorylation. Noteworthy, this was also observed under conditions where other components of serum might be bound by zymosan particles, for instance, serum IgG, thereby suggesting their potential involvement in Syk activation. The induction of cytokines showed a changing pattern consistent with the changes observed in the signaling pathways. IC induced monocyte chemoattractant protein-1 (MCP-1)/CC chemokine ligand 2 (CCL2), interleukin (IL)-1beta, and eotaxin-2/CCL24, which were not observed with C3bi-coated IC. Zymosan induced the expression of tumor necrosis factor alpha (TNF-alpha), TNF-beta, IL-10, IL-6, and MCP-2/CCL8, whereas the cytokine signature of C3bi-coated zymosan also included interferon-inducible protein 10/CXC chemokine ligand 10, platelet-derived growth factor-BB, and I-309/CCL1. Taken together, these findings indicate that C3bi targets the phagocytic cargo, and engagement or diversion of the Syk route determines the phagocyte response.

Dietary beta-1,3 glucan potentiates innate immunity and disease resistance of Asian catfish, Clarias batrachus (L.)

This study investigated the effects of short and prolonged administration of a yeast beta-glucan on non-specific immune parameters, growth rate and the disease resistance of Asian catfish, Clarias batrachus. Fish fed with a basal diet (control) and test diet (basal diet supplemented with 0.1% glucan) for 1, 2 and 3 weeks were assayed for superoxide production, serum myeloperoxidase (MPO) content, natural haemagglutinin level, complement and lysozyme activities. Fish were weighed at weekly intervals and specific growth rate (SGR, % increase in body weight per day) was determined. After each week, fish were challenged with Aeromonas hydrophila to measure the level of protection. Results showed that glucan administration at 0.1% in feed, significantly (P<0.05) enhanced MPO and lysozyme levels, superoxide production, haemagglutination titre and level of protection against A. hydrophila challenge, irrespective of length of exposure. The alternative complement activity and SGR were not affected by the dietary supplementation of yeast glucan. As glucan feeding at 0.1% for 1 week is able to enhance the non-specific immunity and disease resistance of catfish efficiently, short-term feeding might be used in farmed catfish diets to enhance disease resistance.

The effect of PGG-beta-glucan on neutrophil chemotaxis in vivo

The beta-glucans are long-chain polymers of glucose in beta-(1,3)(1,6) linkages, which comprise the fungal cell wall and stimulate cells of the innate immune system. Previous in vitro studies have shown the ability of beta-glucan to increase the chemotactic capacity of human neutrophils. The current study examined an in vivo correlate of that observation by testing the hypothesis that systemic beta-glucan treatment would result in enhanced migration of neutrophils into a site of inflammation and improve antimicrobial function. A model of acute inflammation was used in which polyvinyl alcohol sponges were implanted subcutaneously into the dorsum of rats. Animals treated with beta-glucan showed a 66 +/- 6% and 186 +/- 42% increase in wound cell number recovered 6 and 18 h postwounding, respectively. Increased migration did not correlate with increased chemoattractant content of wound fluid, alterations in neutrophil-induced loss of endothelial barrier function, or changes in neutrophil adhesion to endothelial cells. Systemic administration of SB203580 abrogated the enhanced migration by beta-glucan without altering normal cellular entry into the wound. Studies also showed a priming effect for chemotaxis and respiratory burst in circulating neutrophils isolated from beta-glucan-treated animals. Heightened neutrophil function took place without cytokine elicitation. Furthermore, beta-glucan treatment resulted in a 169 +/- 28% increase in neutrophil number and a 60 +/- 9% decrease in bacterial load in the bronchoalveolar lavage fluid of Escherichia coli pneumonic animals. Taken together, these findings demonstrate that beta-glucan directly affects the chemotactic capacity of circulating neutrophils through a p38 mitogen-activated protein kinase-dependent mechanism and potentiates antimicrobial host defense.

Natural microbial polysaccharide sulphoethyl glucan as antigenotoxic and cancer preventing agent

Naturally occurring polysaccharides isolated from the yeasts are the substances with versatile intriguing biomodulatory activities. One of the novel derivatives prepared from the (1 --> 3)-beta-D-glucan isolated from the cell walls of baker's yeast Saccharomyces cerevisiae is sulfoethyl glucan (SEG). Its DNA-protective, antimutagenic, anticlastogenic and cytotoxic/cytostatic enhancing effect was evaluated using five eukaryotic systems. SEG showed bioprotective effect in recombination- repair-deficient strain of alga Chlamydomonas reinhardtii against methyl methanesulfonate-induced genotoxicity, antimutagenic effect against ofloxacin-induced genetic changes in yeast Saccharomyces cerevisiae assay and anticlastogenic activity in plants Vicia sativa and Vicia faba assays against maleic hydrazide-induced clastogenicity. In the combined application with cytostatic drug vumon, SEG exerted enhancement of the drug's cytotoxic/cytostatic effect in the cell revitalization assay using mouse leukemia cells. The study sheds light on the possible mechanisms of actions and utilization of this microbial polysaccharide derivative in the cancer prevention and therapy.

Effects of beta-D-glucan on steroid-induced impairment of colonic anastomotic healing

BACKGROUNDS/AIMS

Inflammation during the early phase of anastomotic wound healing is an essential cellular response and is suppressed by corticosteroids. The anti-inflammatory effect of corticosteroids is largely responsible for its impairment of wound healing in bowel anastomosis. Beta-D-glucan, a commonly used macrophage activator, has been shown to improve anastomotic wound healing under normal conditions. In the present study, we have investigated the effects of beta-D-glucan on anastomotic wound healing in rats treated with long-term corticosteroid.

METHODOLOGY

92 male Sprague-Dawley rats were randomized into four groups. 1 : control, 2: control + beta-D-glucan, 3 : steroid, 4 : steroid + beta-D-glucan. Methylprednisolone (5mg/kg) was injected IM daily for 14 days in groups 3 and 4. After 14 days, following anaesthesia and laparotomy, colonic anastomosis was performed 3 cm away from the peritoneal reflection of rectum. In groups 2 and 4, 100mg/kg beta-D-glucan was administered orally for 7 days before laparotomy. On postoperative day 3, relaparotomies were performed and bursting pressures, hydroxyproline levels and histopathological specimens were studied.

RESULTS

The mean values of bursting pressures groups were 50.8 (95% CI 46.99-56.50), 58.2 (95% CI 54.49-61.90), 32.0 (95% CI 29.21-34.98), 45.9 (95% CI 43.09-48.80) respectively. The differences of the mean values of the groups between group 1 and 2 and also 3 were significant (p = 0.002, p < 0.001). The mean values of hydroxyproline of the groups were 3.8 (95% CI 3.56-4.06), 4.7 (95% CI 4.50-5.04), 2.9 (95% CI 2.73-3.20), 3.9 (95% CI 3.65-4.22) respectively. The differences of the values of the groups between control (group1) and group 2 and also group 3 were significant (p = 0.001, p < 0.001). In histopathological examination, increased macrophages and fibroblast population were observed in specimens from beta-D-glucan-treated animals.

CONCLUSION

The results indicate that in rat model, oral administration of beta-D-glucan causes a significant improvement in the healing of anastomotic wound impaired by long-term corticosteroid administration.

Prevention of bacterial translocation using beta-(1-3)-D-glucan in small bowel ischemia and reperfusion in rats

PURPOSE: To investigate the role of beta-(1-3)-D-glucan on 99mTc labelled Escherichia coli translocation and cytokines secretion in rats submitted to small bowel ischemia/reperfusion injury. METHODS: Five groups (n=10 each) of Wistar rats were subjected to control(C), sham(S), group IR subjected to 45 min of bowel ischemia/60 min of reperfusion(I/R), and group I/R+glucan subjected to 45 min of bowel ischemia/60 min of reperfusion(I/R) and injected with 2mg/Kg intramuscular. Translocation of labelled bacteria to mesenteric lymph nodes, liver, spleen, lung and serum was determined using radioactivity/count and colony forming units/g(CFU/g). Serum TNFalpha, IL-1beta, IL-6, IL-10 were measured by ELISA. RESULTS: CFU/g and radioactivity/count were higher in I/R than in I/R+glucan rats. In C, S and S+glucan groups, bacteria and radioactivity/count were rarely detected. The I/R+glucan rats had enhancement of IL-10 and suppressed production of serum TNFalpha, IL-1beta and, IL-6, compared to I/R untreated animals. CONCLUSION: The beta-(1-3)-D-glucan modulated the production of pro-inflammatory and anti-inflammatory cytokines during bowel ischemia/reperfusion, and attenuated translocation of labelled bacteria.

Immunomodulatory effects of beta-glucan on neutrophil function in fathead minnows (Pimephales promelas Rafinesque, 1820)

Stimulatory effects of yeast beta-1,3-1,6-glucans on neutrophils have long been recognized, but effects of glucans on degranulation of primary granules in fish neutrophils have not been previously reported. Neutrophil function was monitored during in vitro and in vivo application of glucans to non- (NS), acute- (AS) and chronically stressed (CS) fish. beta-Glucan proved to be a strong and quick (80%, 2 min) stimulant of degranulation. Dietary glucan increased degranulation in NS fish, and prevented a decrease in AS fish. Degranulation in CS fish returned to NS levels 3 days after the glucan diet was fed. Fathead minnows appear to be a useful model to investigate neutrophil degranulation in fish exposed to different environmental conditions and immunomodulators. Use of beta-glucans in fish diets prior to AS and during chronic stress can enhance neutrophil function, potentially increasing disease resistance and survival rates after transportation or exposure to poor water quality.

The role of natural biopolymers in genotoxicity of mutagens/carcinogens elimination

Nowadays naturally occurring compounds with the potential antimutagenic and anticarcinogenic effects are of great importance for their prospective use in cancer chemoprevention and treatment. The new water soluble derivative of microbial polysaccharide beta-D-glucan-carboxymethyl glucan (CMG) belongs to such a category of natural substances. CMG isolated from the cell wall of baker's yeast Saccharomyces cerevisiae is included into the class of biopolymers known as biological response modifiers (BRMs) with a broad range of activities, above all ones interfering with cancer therapy. It was demonstrated on four experimental model systems that biological and consequential medicinal importance of CMG is based on the combined application with another active compound. In the Saccharomyces cerevisiae antimutagenicity assay CMG significantly reduced ofloxacin-induced mutagenicity in the yeast strain D7. CMG exerted bioprotective (anti-toxic and antimutagenic) effect after its simultaneos application with methyl methanesulphonate on the repair-deficient strain uvs10 of the unicellular green alga Chlamydomonas reinhardtii. In the Vicia sativa simultaneous phytotoxicity and anticlastogenicity assay CMG exerted statistically significant anticlastogenic efect against maleic hydrazide-induced clastogenicity in Vicia sativa L. Only in the Salmonella/microsome assay CMG did not exert statistically significant antigenotoxic effect, despite of the fact that it reduced 9-aminoacridine-induced mutagenicity in S. typhimurium TA97, but his(+) revertants decreasing was statistically significant only at the highest CMG concentration used. The data presented unambiguously documented that even biopolysaccharides (e.g., derivatives of beta-glucan) belonging to the most abundant class of natural biopolymers may contribute to cancer prevention and therapy.

Effects of β-glucan obtained from the Chinese herb Astragalus membranaceus and lipopolysaccharide challenge on performance, immunological, adrenal, and somatotropic responses of weanling pigs1

A total of 108 crossbred piglets (7.75 +/- 0.24 kg of BW) weaned at 28 d was used to study the interactive effects of beta-glucan obtained from the Chinese herb Astragalus membranaceus (AM) and Escherichia coli lipopolysaccharide (LPS) challenge on performance, immunological, adrenal, and somatotropic responses of weaned pigs. The treatments were in a 2 x 3 factorial arrangement; main effects were level of Astragalus membranaceus glucan (AMG; 0, 500, or 1,000 mg/kg; as-fed basis) and presence of immunological challenge (with or without LPS). The experiment included six replicate pens per treatment and three pigs per pen. Lipopolysaccharide challenges were conducted on d 7 and 21 of the trial. Blood samples were obtained from the vena cava from one pig per pen at 3 h after LPS challenge to determine plasma responses. Weight gain and feed:gain ratio were unaffected by glucan. However, there was a quadratic effect on feed intake (P < 0.05): pigs fed 500 mg of glucan/kg had the highest feed intake. Immunological challenge with LPS decreased weight gain (P = 0.02). An interaction (P = 0.01 to 0.09) between AMG and LPS was observed for glucose, IL-1beta, PGE2, and cortisol. Astragalus membranaceus glucan had a quadratic effect on the plasma concentrations of glucose, IL-1beta, PGE2, and cortisol (P < 0.05) after both LPS challenges. Plasma concentrations of glucose, IL-1beta, PGE2, and cortisol (P < 0.05) were all increased in LPS-challenged pigs compared with the control pigs after both LPS challenges. The IGF-I concentrations were less for LPS-challenged pigs than for unchallenged pigs. The lymphocyte proliferation response of peripheral blood induced by 5 microg of concanavalin A/mL (P < 0.01) and IL-2 bioactivity (P < 0.05) increased linearly with increasing addition of glucan. Pigs challenged with LPS had greater T-lymphocyte proliferation (P = 0.06) and IL-2 bioactivity (P = 0.07) than unchallenged pigs after the first immunological challenge but not after the second. In conclusion, although glucan did not improve pig performance under the conditions of the present experiment, when included at 500 mg/kg, it decreased the release of inflammatory cytokine and corticosteroid and improved the lymphocyte proliferation response of weanling piglets via enhanced IL-2 bioactivity.

Soy isoflavone aglycone modulates a hematopoietic response in combination with soluble beta-glucan: SCG

Soy isoflavone aglycones (IFAs) have a wide range of biological actions that suggest they may be of use in cancer prevention. On the other hand, a branched beta-glucan from Sparassis crispa (SCG) is a major 6-branched 1,3-beta-D-glucan in an edible/medicinal mushroom: Sparassis crispa showing antitumor activity. We have previously reported that both oral and intraperitoneal administration of SCG enhanced the hematopoietic response in cyclophosphamide (CY)-induced leukopenic mice. In this study, we investigated the hematopoietic response due to IFA in combination with SCG in CY-induced leukopenic mice. The oral administration of IFA in combination with SCG synergistically enhanced the number of white blood cells, and increased spleen weight. Analyzing the leukocyte population by flow cytometry, the combination of IFA and SCG increased the number of monocytes and granulocytes in the spleen. Taken together, the combination of IFA and SCG synergistically provides the hematopoietic responses that are enhanced over IFA or SCG alone.

[Antitumor effects of intratumoral injection of Basidiomycetes preparations]

The antitumor effects of Basidiomycetes preparations in an experimental mouse model, the "double grafted tumor system" were analyzed. Some BRMs prevented metastases by utilizing the anti-tumor immunological cascade reactions, which activates macrophages in the body. The following Basidiomycetes preparations were analyzed: PSK was a hot water extract of cultured mycelia from Coliolus versicolor and a protein bound beta-glucan. Matsumax was extracted from mycelia of Tricholoma matsutake and was a protein bound (38%) a-glucan. The Agaricus preparation was extracted from fruit bodies of Agaricus blazei and a protein-bound (17%) a-glucan, beta-glucan. Himematsutake preparation was extracted from fruit body of Agaricus blazei (Himematsutake) and a protein bound (5%) glucan. Lentinan was purified from fruit bodies of Lentinus edodes and is a purified beta-glucan. PSK cured both primary and metastatic tumors in the double grafted tumor system. Lentinan inhibited the growth of neither primary nor metastatic tumors. Matsumax and Agaricus preparation cured primary tumor and inhibited the growth of metastatic tumor. Himematsutake preparation inhibited the growth of primary tumor. Immunosuppresive acidic protein (IAP) is produced by activated mactrophates. The PSK, Matsumax, Agaricus preparation and Himematsutake preparation induced IAP but Lentinan did not.

Administration of yeast glucan enhances survival and some non-specific and specific immune parameters in carp (Cyprinus carpio) infected with Aeromonas hydrophila

Effects of beta-glucan administration on survival and immune modulations were studied in Cyprinus carpio against the bacterial pathogen, Aeromonas hydrophila. Beta-glucan was extracted from Saccharomyces cervisiae and purified. A virulent strain of the pathogen A. hydrophila was collected from infected fish. Different concentrations of beta-glucan were administered to test animals on day 1, 3 and 5 through different routes (intraperitoneal injection (ip), bathing and oral administration). Control and test animals were challenged by ip injection of LD50 concentration of A. hydrophila on day 7 and mortality was observed and Relative Percent Survival (RPS) was calculated. Intraperitoneal injection of 500 microg of glucan significantly enhanced the RPS; bathing and oral administration of glucan did not influence the RPS. On day 7, test animals injected with 100, 500 and 1000 microg of glucan had a significant increase in total blood leucocyte counts and an increase in the proportion of neutrophils and monocytes. Superoxide anion production by kidney macrophages was also elevated. RT-PCR and northern blot analysis of interleukin-1 mRNA showed elevated expression in kidney on day 7 in fish injected with glucan. Glucan had an adjuvant effect on antibody production as pretreatment by injection of 100-1000 microg glucan/fish resulted in the highest antibody titer against A. hydrophila following vaccination. Classical and alternative complement pathways were not affected by glucan administration by any of the three routes.

Beta1-adrenergic receptor mediation in the lichen glucan PB-2-induced enhancement of long-term potentiation in the rat dentate gyrus in vivo

The mechanism underlying the enhancement of long-term potentiation (LTP) induced by the systemic administration of PB-2, an alpha(1-3)(1-4)glucan-containing fraction extracted from the lichen Flavoparmelia baltimorensis and a putative LTP-enhancing agent, was investigated in the rat dentate gyrus in vivo. Particular attention was paid to the role of adrenaline beta-receptors. An intravenous (i.v.) injection of PB-2 enhanced the induction of LTP, which was in turn inhibited by an i.v. injection of the adrenaline beta1-receptor antagonist atenolol. An intracerebroventricular injection of atenolol did not affect the induction of LTP, but completely suppressed the PB-2-induced enhancement of LTP. The infusion of atenolol into the recording site attenuated the PB-2-induced facilitation of LTP. These results suggest that the adrenaline beta1-receptors contribute to the enhancement of LTP induced by the systemic administration of PB-2, and that the functional beta1-receptors are located both centrally and peripherally.

Galactose-PEG dual conjugation of beta-(1-->3)-D-glucan schizophyllan for antisense oligonucleotides delivery to enhance the cellular uptake

Antisense oligonucleotides (AS ODNs) are applied to silence a particular gene, and this approach is one of the potential gene therapies. However, naked oligonucleotides are easy to be degraded or absorbed in biological condition. Therefore, we need a carrier to deliver AS ODNs. This paper presents galactose moieties that were conjugated to the side chain of SPG to enhance cellular ingestion through endocytosis mediated by asialoglycoprotein receptor specifically located on parenchymal liver cells. We introduced galactose with two types of chemical bonds; amide and amine, and the amine connection showed lower ingestion and more toxicity than the amide one. Since PEG was known to induce endocytosis escape, we combined PEG and galactose aiming to provide both cellular up-take and subsequent endocytosis escape. We designed lactose or galactose moieties to attach to the end of the PEG chain that connects to the SPG side chain. When the PEG had the molecular weight of 5000-6000, the antisense effect reached the maximum. We believe that this new type of galactose and PEG dual conjugation broaden the horizon in antisense delivery.

Anti-diabetic activity of beta-glucans and their enzymatically hydrolyzed oligosaccharides from Agaricus blazei

Beta-glucans were prepared from Agaricus blazei Murill by repeated extraction with hot water. The average molecular weights of beta-glucans were 30-50 kDa by gel filtration chromatography. Oligosaccharides (AO), derived from hydrolyzing beta-glucans with an endo-beta-(1-->6)-glucanase from Bacillus megaterium, were mainly di- and tri-saccharides. Though beta-glucans and AO both showed anti-hyperglycemic, anti-hypertriglyceridemic, anti-hypercholesterolemic, and anti-arteriosclerotic activity indicating overall anti-diabetic activity in diabetic rats, AO had about twice the activity of beta-glucans with respect to anti-diabetic activity.

A rapid, direct assay to measure degranulation of primary granules in neutrophils from kidney of fathead minnow (Pimephales promelas Rafinesque, 1820)

A direct, rapid, quantitative colorimetric assay to determine neutrophil primary granule degranulation was adapted for use with fathead minnow kidney neutrophils. The assay measures the exocytosis of myeloperoxidase (MPO) using 3,3',5,5'-tetramethylbenzidine as a substrate. The assay was validated by comparing the total myeloperoxidase content of neutrophil populations obtained from adult cattle, as a known positive, and fish; evaluating the effects of calcium ionophore (CaI), phorbol myristate acetate (PMA), aqueous solution of beta-glucan (MGAQ) and zymosan (Z) with and without cytochalasin B (cyto B) as stimulants of degranulation; determining the kinetics of primary granule exocytosis and detecting changes in degranulation when fish were exposed to stress and anaesthesia with MS-222. The MPO assay detected MPO activity in fathead minnow neutrophils that correlated to neutrophil numbers, confirmed that degranulation was increased when CaI was used compared to other stimulants, determined degranulation peak at 60 min and confirmed decreased degranulation after exposure to handling and crowding stress, with and without MS-222. Therefore, the MPO assay is capable of detecting important differences that may occur in degranulation of fathead minnow kidney neutrophil primary granules and in total neutrophil myeloperoxidase content.

Cation fluxes cause plasma membrane depolarization involved in beta-glucan elicitor-signaling in soybean roots

Inducible and specific ion fluxes on plasma membranes represent very early events during elicitation of plant cells. The hierarchy of such ion fluxes involved is still unknown. The effect of Phytophthora sojae-derived beta-glucan elicitors on the plasma membrane potential as well as on surface K+, Ca2+, and H+ fluxes has been investigated on soybean roots using ion-selective microelectrodes. Beta-Glucans with different degrees of polymerization transiently depolarized the plasma membrane. The elicitor concentration necessary for half-maximal depolarization closely resembled the corresponding binding affinities of soybean root membranes toward the respective beta-glucans. Upon repeated elicitor treatment, the root cells responded partially refractory, suggesting a complex responsiveness of the system. Within the root hair space, characteristic decreasing K(+)- and Ca(2+)-free concentrations were induced by the elicitors, probably causing depolarization through the influx of positive charges. Whereas K+ fluxes were inverted after passing the K+ equilibrium (Nernst-) potential, Ca2+ influx continued. No anion fluxes sufficient to account for charge compensation were observed under the same experimental conditions. K+ and Ca2+ fluxes as well as depolarization were inhibited by 100 microM or less of the Ca2+ antagonist La3+. Contrasting other systems, in soybean the main cause for elicitor-induced plasma membrane depolarization is the activation of cation instead of anion fluxes.

The effect of beta-glucan administration on macrophage respiratory burst activity and Atlantic salmon, Salmo salar L., challenged with amoebic gill disease--evidence of inherent resistance

Previous studies have demonstrated that beta-glucans stimulate Atlantic salmon, Salmo salar L., head kidney macrophages both in vitro and in vivo and increase protection against various pathogens. Based on our previous work that showed potent immunostimulatory CpG motif-containing oligodeoxynucleotides increased resistance to amoebic gill disease (AGD), the present study investigated the immunostimulatory effects of three commercial beta-glucan-containing feeds and their ability to increase resistance to AGD. All three commercial beta-glucans were able to stimulate the respiratory burst activity of Atlantic salmon head kidney macrophages in vitro, albeit at different times and concentrations. However, dietary incorporation of the beta-glucans was unable to stimulate the in vivo respiratory burst activity of head kidney macrophages, or serum lysozyme production, and did not increase resistance against AGD. However, this trial showed for the first time that a small subpopulation of Atlantic salmon subjected to a severe AGD infection was able to resist becoming heavily infected and furthermore survive the challenge.

Hypoglycemic activity of polysaccharide fractions containing ß-glucans from extracts of Rhynchelytrum repens (Willd.) C.E. Hubb., Poaceae

Beta-glucans are soluble fibers with physiological functions, such as interference with absorption of sugars and reduction of serum lipid levels. The objective of the present study was to analyze the distribution of beta-glucans in different tissues of the African grass species Rhynchelytrum repens and also to evaluate their hypoglycemic activity. Leaf blades, sheaths, stems, and young leaves of R. repens were submitted to extraction with 4 M KOH. Analysis of the fractions revealed the presence of arabinose, glucose, xylose, and traces of rhamnose and galactose. The presence of beta-glucan in these fractions was confirmed by hydrolyzing the polymers with endo-beta-glucanase from Bacillus subtilis, followed by HPLC analysis of the characteristic oligosaccharides produced. The 4 M KOH fractions from different tissues were subjected to gel permeation chromatography on Sepharose 4B, with separation of polysaccharides with different degrees of polymerization, the highest molecular mass (above 2000 kDa) being found in young leaves. The molecular mass of the leaf blade polymers was similar (250 kDa) to that of maize coleoptile beta-glucan used for comparison. The 4 M KOH fraction injected into rats with streptozotocin-induced diabetes showed hypoglycemic activity, reducing blood sugar to normal levels for approximately 24 h. This performance was better than that obtained with pure beta-glucan from barley, which decreased blood sugar levels for about 4 h. These results suggest that the activity of beta-glucans from R. repens is responsible for the use of this plant extract as a hypoglycemic drug in folk medicine.

Enhancement of Radioprotection and Anti-Tumor Immunity by Yeast-Derived β-Glucan in Mice

Intraperitoneal injection of beta-glucan was shown to greatly delay mortality in mice exposed to whole-body X-ray radiation and tumor growth in tumor-bearing mice. Since the leukocyte and lymphocyte numbers were increased by a single dose of beta-glucan, the radioprotective effect of beta-glucan is probably mediated, at least in part, by a hemopoietic action in irradiated mice. In addition, both natural killer (NK) and lymphokine-activated killer (LAK) activities were significantly increased by repeated doses of beta-glucan. Augmented immunological activity as seen in increased NK and LAK activity by beta-glucan seems to play a role in preventing secondary infections associated with irradiation, and probably contributes to the attenuated tumor growth in tumor-bearing mice through enhanced anti-tumor immunity. These results suggest that beta-glucan may be a promising adjunct treatment for cancer patients receiving radiotherapy.

Dual effects of the lichen glucan PB-2, extracted from Flavoparmelia baltimorensis, on the induction of long-term potentiation in the dentate gyrus of the anesthetized rat: possible mediation via adrenaline beta- and interleukin-1 receptors

We have previously found that oral or intravenous (i.v.) administration of the polysaccharide fraction PB-2, extracted from the lichen Flavoparmelia baltimorensis, facilitated the induction of long-term potentiation (LTP) in the dentate gyrus (DG) in vivo. In this study, the mechanism underlying the effect of PB-2 on the induction of LTP was investigated in the DG of anesthetized rat focusing on the contribution of the interleukin-1 (IL-1) receptor and the adrenaline beta-receptor. An i.v. injection of IL-1ra (10(-9) g/kg), an antagonist of the IL-1 receptor, had no effect on the basal response in the DG; however, this treatment augmented the enhancement of LTP induced by a single i.v. injection of PB-2 (10(-3) g/kg). This potentiating effect was also observed following intracerebroventricular (i.c.v.) injection of IL-1ra (10(-15)-10(-11) g). An i.v. injection of IL-1beta (3.5 x 10(-15)-3.5 x 10(-9) g/kg) inhibited the induction of LTP, which was diminished by the previous application of IL-1ra. These results suggest that the activation of the IL-1 receptor induces the suppression of LTP in PB-2-treated rats, and that endogenous IL-1beta contributes to the IL-1 receptor activation. An i.c.v. infusion of metoprolol (7.5 x 10(-6) g), an antagonist of the adrenaline beta(1)-receptor, attenuated the enhancement of LTP induced by an i.v. injection of PB-2. These results suggest that PB-2 has two different effects on the LTP, an enhancing effect and an inhibiting one, and that it exhibited the significant enhancing effect on the LTP as a total balance of these effects.

Suppressing effects of daily oral supplementation of beta-glucan extracted from Agaricus blazei Murill on spontaneous and peritoneal disseminated metastasis in mouse model

PURPOSE

The Basidiomycete fungus Agaricus blazei Murill has traditionally been used as a health food for the prevention of cancer.

METHODS

We examined whether beta-(1-6)-D: -glucan extracted from A. blazei is a potential anticancer agent in an in vitro and in vivo animal model.

RESULTS

Here we show that (1) beta-glucan had cytotoxic effect against human ovarian cancer HRA cells, but not against murine Lewis lung cancer 3LL cells, in vitro; (2) beta-glucan promotes p38 MAPK activity for suppressing HRA cell proliferation and amplifying the apoptosis cascade; (3) beta-glucan stimulates translocation of the proapoptotic protein, Bax, from the cytosol to mitochondria, cytochrome c release, and subsequent caspase-9 activation; (4) treatment with SB203580, a p38 MAPK-specific inhibitor, suppresses beta-glucan-induced effects, indicating that activation of p38 MAPK is involved in the suppression of cell proliferation and mitochondrial activation-mediated cell death pathway; (5) in mice, oral supplementation with beta-glucan reduces pulmonary metastasis of 3LL cells and peritoneal disseminated metastasis of HRA cells and inhibits the growth of these metastatic tumors in lung or peritoneal cavity, in part, by suppressing uPA expression; and (6) in an in vivo experimental metastasis assay, however, the oral supplementation with beta-glucan after i.v. tumor cell inoculation did not reduce the number of lung tumor colonies.

CONCLUSION

Treatment with beta-glucan may be beneficial for cancer patients with or at risk for metastasis. The beta-glucan-dependent signaling pathways are critical for our understanding of anticancer events and development of cancer therapeutic agents.

The antioxidant effect of beta-Glucan on oxidative stress status in experimental spinal cord injury in rats

This study was performed to investigate the antioxidant effect of beta-Glucan in experimental spinal cord injury (SCI). Injury was produced using weight-drop technique in rats. beta-Glucan was given by intraperitoneal injection following trauma. The rats were sacrificed at the sixth day of injury. Oxidative stress status was assessed by measuring the spinal cord tissue content of Malonyldialdehyde (MDA), Superoxide Dismutase (SOD) and Gluthatione Peroxidase (GSH-Px) activities. No effect of beta-Glucan on SOD and MDA activities was found but, GSH-Px levels were found to decrease to the baseline (preinjury) levels when it was compared to untreated group (U=0.000; p=0.002). According to our results, beta-Glucan works like a scavenger and has an antioxidant effect on lipid peroxidation in spinal cord injury.

Curdlan and other bacterial (1→3)-β-d-glucans

Three structural classes of (1-->3)-beta-D-glucans are encountered in some important soil-dwelling, plant-associated or human pathogenic bacteria. Linear (1-->3)-beta-glucans and side-chain-branched (1-->3,1-->2)-beta-glucans are major constituents of capsular materials, with roles in bacterial aggregation, virulence and carbohydrate storage. Cyclic (1-->3,1-->6)-beta-glucans are predominantly periplasmic, serving in osmotic adaptation. Curdlan, the linear (1-->3)-beta-glucan from Agrobacterium, has unique rheological and thermal gelling properties, with applications in the food industry and other sectors. This review includes information on the structure, properties and molecular genetics of the bacterial (1-->3)-beta-glucans, together with an overview of the physiology and biotechnology of curdlan production and applications of this biopolymer and its derivatives.

Correlation of structure to antitumor activities of five derivatives of a beta-glucan from Poria cocos sclerotium

A water-insoluble (1-->3)-beta-D-glucan isolated from fresh sclerotium of Poria cocos was, respectively, sulfated, carboxymethylated, methylated, hydroxyethylated, and hydroxypropylated, to afford five water-soluble derivatives. Their weight-average molecular masses (Mw) and intrinsic viscosities ([eta]) were determined by size-exclusion chromatography combined with laser light scattering (SEC-LLS), LLS, and viscometry in phosphate buffer solution (PBS) at 37 degrees C. The antitumor activities, against Sarcoma 180 tumor cell (S-180) and gastric carcinoma cell strain (MKN-45 and SGC-7901) of the native beta-glucan and the five derivatives, were tested in vitro and in vivo. The Mw values of the five derivatives in PBS were determined to be 3.8 x 10(4), 18.9 x 10(4), 16.0 x 10(4), 76.8 x 10(4), and 224.3 x 10(4), respectively. The high Mw values of the hydroxyethylated and hydroxypropylated derivatives in aqueous solution resulted from aggregation, and their true Mw values obtained in dimethyl sulfoxide were 20.1 x 10(4) and 19.1 x 10(4). The sulfated and carboxymethylated derivatives having DS of 1.0-1.3 show good water solubility, and exist as relatively expanded chains in aqueous solution. Interestingly, the native beta-glucan did not show antitumor activity, whereas the sulfated and carboxymethylated derivatives exhibit significant antitumor activities against S-180 and gastric carcinoma tumor cells. This work showed that good water solubility, relatively high chain stiffness, and moderate molecular mass of the derivatives in aqueous solution contribute beneficial to enhancement of antitumor activity.

Purified beta-glucan as an abiotic feed additive up-regulates the innate immune response in immature chickens against Salmonella enterica serovar Enteritidis

Functionally, the innate immune system of immature chickens is inefficient during the first week posthatch. This immunological inefficiency enables pathogens such as Salmonella enterica serovar Enteritidis (SE) to invade and colonize the visceral organs of immature chickens. The objective of this study was to evaluate the effect of purified beta-glucan as an immunomodulator of the innate immune response. beta-glucan, as a feed additive, significantly provided protection against SE organ invasion in young chickens (P<0.05). The functional efficiency of heterophils isolated from neonatal chickens fed a beta-glucan ration was significantly (P<0.05) up-regulated when compared to heterophils isolated from chickens fed a control ration as determined with an array of functional assays. Phagocytosis, bactericidal killing, and oxidative burst were significantly increased in heterophils isolated from chickens fed the purified beta-glucan ration (P<0.05). To our knowledge, this is the first report of a purified beta-glucan feed additive significantly decreasing the incidence of SE organ invasion in immature chickens and up-regulating the functional abilities of heterophils isolated from immature chickens against an invading pathogen, SE.

Catalase and alternative oxidase cooperatively regulate programmed cell death induced by beta-glucan elicitor in potato suspension cultures

In potato (Solanum tuberosum L.) suspension cells, the expression of the gene encoding alternative oxidase (AOX) and H2O2 accumulation were induced by treatment with beta-glucan elicitor. The inhibition of catalase activity enhanced both AOX mRNA expression and the production of H2O2, whereas the ascorbate peroxidase inhibitor did not have any effect on these responses. Simultaneous inhibition of catalase and AOX activities in elicited cells dramatically increased H2O2 accumulation, leading to the disruption of mitochondrial membrane potential (deltapsi(m)) and programmed cell death (PCD). The results demonstrate, for the first time, that not only AOX but also catalase plays a central role in the suppression of mitochondrial deltapsi(m) breakdown and PCD induced by beta-glucan elicitor.

Short- and long-term effects of a dietary yeast beta-glucan (Macrogard) and alginic acid (Ergosan) preparation on immune response in sea bass (Dicentrarchus labrax)

The present study investigated the immunomodulatory activity of Ergosan, an algal extract containing alginic acid, and Macrogard, a yeast extract containing beta-glucans, on innate and specific immunity in sea bass (Dicentrarchus labrax). Four cycles of experimental feeding using normal fish feed formulation (control group) supplemented with Ergosan (0.5%) or Macrogard (0.1%) were performed at 60-day intervals (15 days of treatment+45 days of suspension). Serum complement, lysozyme, total proteins and heat shock protein (HSP) concentrations were measured at 15, 30 and 45 days from the end of the first 15-day feeding cycle (short term) and 45 days after the end of each feeding cycle over a 35-week period (long term). The percentage of B- and T-lymphocytes in peripheral blood leucocytes and gut were measured over long-term trial. Significant elevation (P < 0.05) in serum complement activity occurred in sea bass fed with alginic acid and glucans, at 15 days from the end of first cycle of treatment. Significant elevation (P < 0.05) in serum lysozyme, gill and liver HSP concentration were observed in the same experimental groups at 30 days from the end of treatment, whereas a significant increase (P < 0.05) of complement activity was only observed in fish that received an Ergosan diet. At 45 days from the end of treatment, complement, lysozyme and HSP concentration did not differ among groups. Over the long-term period, no significant differences were observed in innate and specific immune parameters, survival, growth performances and conversion index in treated and control fish. A dramatic decrease of both innate and acquired immune parameters was observed during the winter season in all groups, followed by a partial recovery when water temperature increased. Reduction in complement and lysozyme activities was significatively correlated (p < 0.01) to water temperature variation. The results suggested the potential of alginic acid and beta-glucans to activate some innate immune responses in sea bass, and particularly under conditions of immunodepression related to environmental stress.

Granulocyte-macrophage colony-stimulating factor (GM-CSF) regulates cytokine induction by 1,3-beta-D-glucan SCG in DBA/2 mice in vitro

Sparassis crispa Fr. is an edible/medicinal mushroom that recently became cultivable in Japan. SCG is a major 6-branched 1,3-beta-D-glucan in S. crispa showing antitumor activity. We recently found that the splenocytes from naive DBA/1 and DBA/2 mice strongly react with SCG to produce interferon-gamma (IFN-gamma). In this study, cytokines induced by SCG were screened and found to be IFN-gamma, tumor necrosis factor-alpha (TNF-alpha), granulocyte-macrophage colony-stimulating factor (GM-CSF), and interleukin-12 (IL-12p70). The addition of recombinant murine GM-CSF (rMuGM-CSF) to spleen cell cultures from various strains of mice synergistically enhanced IFN-gamma, TNF-alpha and IL-12p70 in the presence of SCG. In contrast, neutralizing GM-CSF using anti-GM-CSF monoclonal antibody (mAb) significantly inhibited IFN-gamma, TNF-alpha, and IL-12p70 elicited by SCG. We conclude that GM-CSF is a key molecule for cytokine induction by beta-glucan, and GM-CSF induction by SCG is the specific step in DBA/2 mice in vitro.

In vivo pretreatment with PGG-glucan fails to alter cytokine mRNA expression of equine peripheral blood mononuclear cells exposed to endotoxin ex vivo

Twelve healthy horses were assigned to treatment or control groups. Treated horses received PGG-Glucan[ED-1] (1 mg/kg, IV) 24 hours prior to peripheral blood mononuclear cell (PBMC) isolation. PBMCs were isolated and incubated in the presence of lipopolysachharide (LPS). At 0, 6, 12, 24 and 48 hours messenger RNA (mRNA) was extracted. Reverse transcription polymerase chain reaction (PCR) was performed and cytokine mRNA expression for tumor necrosis factor alpha (TNFalpha), interleukin 1beta (IL-1beta), interleukin 10 (IL-10) and interferon gamma (IFN-gamma) determined using real time PCR. A significant effect of LPS stimulation over time was seen on TNFalpha, IL-1beta, IL-10 and IFN-gamma production. No significant difference was observed between the PGG-Glucan treatment group and control cells at any time point.

Immunostimulating properties of intragastrically administered Acetobacter-derived soluble branched (1,4)-beta-D-glucans decrease murine susceptibility to Listeria monocytogenes

We previously found that AC-1, an extracellular polysaccharide, produced by Acetobacter xylinum and composed of (1,4)-beta-D-glucan with branches of glucosyl residues, showed a strong activity to induce production of interleukin-12 (IL-12) p40 and tumor necrosis factor alpha by macrophages in vitro via Toll-like receptor 4 (TLR-4) signaling. In the present study, we examined the effect of oral administration of AC-1 on protective immunity against Listeria monocytogenes. Mice were given AC-1 or phosphate-buffered saline (PBS) intragastrically 2 days before, on the day of, and 2 days after an intraperitoneal inoculation of L. monocytogenes. The survival rate of AC-1-treated mice was significantly improved and bacterial growth in AC-1-treated mice was severely retarded compared to those of PBS-treated mice after infection with L. monocytogenes. IL-12 p40 levels in serum and magnitudes of CD4+ Th1 and CD8+ Tc1 responses against Listeria antigen were significantly higher in AC-1-treated mice than in PBS-treated mice. The effect of AC-1 on antilisterial activity was diminished in C3H/HeJ mice carrying mutated TLR-4. Thus, AC-1, a potent IL-12 inducer through TLR-4, enhanced protective immunity against L. monocytogenes via augmentation of Th1 responses. These results suggest that infectious processes driven by intracellular microorganisms could be prevented to develop by the (1,4)-beta-D-glucan.

Maitake beta-glucan MD-fraction enhances bone marrow colony formation and reduces doxorubicin toxicity in vitro

Previous studies have indicated that MD-fraction (MDF), in which the active component is beta 1,6-glucan with beta 1,3-branches, has anti-tumor activity as an oral agent and acts as an immune adjuvant. Since some other beta glucans appear to promote mobilization of hematopoietic stem cells, the effects of a beta glucan extract from the Maitake mushroom "MD-fraction" on hematopoietic stem cells were examined in a colony forming assay. Here we report for the first time that MDF has a dose response effect on mouse bone marrow cells (BMC) hematopoiesis in vitro. Using the Colony Forming Unit (CFU) assay to detect formation of granulocyte-macrophage (CFU-GM) colonies, and the XTT cytotoxicitiy assay to measure BMC viability, the data showed that the addition of MDF significantly enhanced the development of CFU-GM in a dose range of 50-100 microg/ml (p<0.004). The mechanism of action included significant increase of nonadherent BMC viability, which was observed at MDF doses of 12.5-100 microg/ml (p<0.005). In the presence of Doxorubicin (DOX), MDF promoted BMC viability and protected CFU-GM from DOX induced toxicity. In addition, MDF treatment promoted the recovery of CFU-GM colony formation after BMC were pretreated with DOX. These studies provided the first evidence that MDF acts directly in a dose dependent manner on hematopoietic BMC and enhances BMC growth and differentiation into colony forming cells.

Glucan-like synthetic oligosaccharides: iterative synthesis of linear oligo-beta-(1,3)-glucans and immunostimulatory effects

Small reducing and linear oligo-beta-(1,3)-glucans, which are able to act as phytoallexin elicitors or as immunostimulating agents in anticancer therapy, were synthesized according to an iterative strategy that involved a unique key monosaccharidic donor. To avoid anomeric mixtures, the reducing entity of the target oligomers was first locked with benzyl alcohol and further selective deprotection of the 3-OH with DDQ afforded the desired building block as an acceptor. The latter was then used in a second cycle of glycosylation/deprotection to afford the desired disaccharide, and successive reiterations of this process provided the desired oligomers. Unusual conformational behaviors were observed by standard NMR sequences and supported by NOESY studies. Finally, removal of protecting groups afforded free tri-, tetra-, and pentaglucosides in good overall yields. Two oligosaccharides representing linear laminaritetraose and laminaripentaose were compared to the recently described beta-(1,3)-glucan phycarine. Following an intraperitoneal injection, the influx of monocytes and granulocytes into the blood and macrophages into the peritoneal cavity was comparable to that caused by phycarine. Similarly, both oligosaccharides stimulated phagocytic activity of granulocytes and macrophages. Using ELISA, we also demonstrated a significant stimulation of secretion of IL-1beta. Together these results suggest that the synthetic oligosaccharides have similar stimulatory effects as natural beta-(1,3)-glucans.

β-Glucan enhancement of T cell IFNγ response in swine

Beta-glucan has been shown to enhance anti-tumor and anti-infection functions in animals. Pigs at 4 months of age were infected with porcine reproductive and respiratory syndrome virus (PRRSV), and peripheral blood monocytes (PBMC) were isolated for the detection of interferon gamma (IFNgamma)-producing cells. We found that soluble high molecular weight beta-glucan could increase IFNgamma-producing cell frequency in a dose-dependent manner in the enzyme-linked immunospot assay (ELISPOT) in the absence of antigenic restimulation. A concentration as low as 1.6 microg/ml gave a significant increase and a similarly high enhancement was achieved at concentrations from 3.2 to 100 microg/ml. In PRRSV-specific IFNgamma ELISPOT, soluble beta-glucan elicited increased PRRSV-specific responses at concentrations from 3.2 to 50 microg/ml, but not at 100 microg/ml, whereas insoluble beta-glucan had no effect. Soluble beta-glucan augmented the porcine cellular immune response in an antigen-independent fashion, whereas insoluble beta-glucan had no activity. This finding suggests that soluble beta-glucan may enhance innate antiviral immunity against PRRSV.

The solubilization and biological activities ofAspergillusβ-(1→3)-d-glucan

We have recently demonstrated that the cell wall beta-glucan of Candida albicans could be solubilized by sodium hypochlorite, followed by dimethylsulfoxide-extraction (NaClO-DMSO method). In this study, applying this method to Aspergillus spp., we prepared mycelial cell wall beta-glucan and examined its physical properties and immunotoxicological activity. The acetone-dried mycelia of Aspergillus spp. were oxidized by the NaClO-DMSO method. An analysis of (13)C NMR spectra revealed the preparations to be composed of alpha-(1 --> 3) and beta-(1 --> 3)-D-glucan. Also, the proportion of alpha-(1 --> 3) and beta-(1 --> 3)-D-glucan varied. Furthermore, a solubilized Aspergillus beta-glucan (ASBG) was prepared from OX-Asp by urea-autoclave treatment. ASBG showed limulus activity similar to Candida solubilized beta-glucan (CSBG), and there was little difference in the activity of ASBG between various Aspergillus spp. ASBG affected the production of IL-8 by human peripheral blood mononuclear cells (PBMC). ASBG should be useful for analyzing the clinical role of beta-glucan.

Evaluation of sulfated fungal β-glucans from the sclerotium of Pleurotus tuber-regium as a potential water-soluble anti-viral agent

Six water-insoluble fractions of fungal beta-glucans extracted by hot alkali (TM8-1 to TM8-6) from the sclerotia of Pleurotus tuber-regium (PTR) having different molecular weights (M(w)) were sulfated to give their corresponding water-soluble derivatives (S-TM8-1 to S-TM8-6) with the degree of sulfation (DS) ranging from 1.14 to 1.74. The in vitro anti-viral activities of the native beta-glucans (TM8s) and their sulfated derivatives (S-TM8s) were evaluated by the cytopathic effect assay (CPE) and the plaque reduction assay (PRA) against four kinds of viruses, including herpes simplex virus type 1 (HSV-1), herpes simplex virus type 2 (HSV-2), respiratory syncytial virus (RSV), and influenza A virus (Flu A). Although TM8s were inactive in inhibiting the viral replication in cell cultures, the S-TM8 fractions with the defined M(w) range had potent anti-viral activity against HSV-1 and HSV-2 as shown by the CPE assay. The PRA results suggested that S-TM8 fractions seemed to exert their anti-viral effect by binding to the viral particles, preventing the latter from infecting the host cells. It was plausible that the negative charges on the polymer chain of S-TM8 could interact with the positively charged glycoproteins on the surface of HSV, minimizing the interaction between the HSV and the negatively charged host cells. The anti-viral activity of the S-TM8s might also be explained by their more extended chain conformation in solution due to an increase in one of their molecular parameter, persistence length (q), as compared to the native TM8s. The potential use of S-TM8s as a water-soluble anti-HSV agent is discussed.

Differential release of MIP-1alpha and eotaxin during infection of mice by Histoplasma capsulatum or inoculation of beta-glucan

OBJECTIVE

In the present study, we evaluated the levels of MIP-1alpha and eotaxin and in vivo migration in the peritoneal cavity model, in mice inoculated with live yeast forms of Histoplasma capsulatum or the beta-glucan cell wall component of this fungus, and the influence of a leukotriene biosynthesis inhibitor, MK886, on the release of these chemokines in relation to cell recruitment.

MATERIALS

Female outbred Swiss mice (N = 4-5 per group, 3-4 wk, were used. Mice were injected i.p. with 1 ml of the 6 x 10(5) live yeast form of the fungus or with 10 microg of beta-glucan from the cell wall fraction, and treated daily with MK886 (1 mg kg(-1), p.o.) or vehicle.

RESULTS

The fungus induced rapid generation of high levels of MIP-1alpha, which remained elevated from 4-48 h whereas very little eotaxin was detected at any time point (Fig. 1A and B). In contrast, the beta-glucan induced a little MIP-1alpha but considerably higher concentrations of eotaxin within the first four hours; however, the level of neither chemokine was sustained (Fig. 2A and B). Treatment of animals with MK886 was effective in reducing the numbers of neutrophils, eosinophils and, to a lesser degree, mononuclear cells accumulating in the peritoneal cavity in response to both the live fungus (Fig. 1C-E) and the cell wall beta-glucan (Fig. 2C-E).

CONCLUSIONS

The results suggest that chemokines and leukotrienes may play key roles in the inflammatory cell influx to H. capsulatum infection or to the inoculation of the beta-glucan cell wall component of this fungus

Liver cells respond to Aspergillus fumigatus with an increase in C3 secretion and C3 gene expression as well as an expression increase in TLR2 and TLR4

Fungal infections by molds like Aspergillus fumigatus are an increasing health problem which can be fatal in immuno-compromised patients. In healthy individuals, these infections are easily eliminated by the innate and acquired immune system. Complement factor 3 (C3) has a key place within the complement cascade and C3 RNA expression can therefore be used to monitor an impending immune response. Employing a liver cell line (HepG2) as a model system, we have examined their responses to A. fumigatus or beta-glucan, a major component of the fungal wall. C3 RNA expression was increased after stimulation with both LPS and A. fumigatus as well as after incubation with beta-glucan, although with different kinetics. C3 protein release into the supernatant followed an inverse bell-shaped curve when cells were incubated with A. fumigatus or beta-glucan while during LPS stimulation, the release was more stable. HepG2 cells also express Toll-like receptors (TLRs) and both for TLR2 and TLR4, an expression increase was found. These data demonstrate that liver cells are able to react specifically to a fungal pathogen without the help of Kupffer cells.

Effects of marine beta-1,3 glucan on immune reactions

Glucans have a long history as nonspecific biological modulators. A novel glucan-Phycarine-was isolated from sporophytes of Laminaria digitata. Phycarine showed significant stimulation of phagocytic activity as well as potentiation of synthesis and release of IL-1, IL-6 and TNF-alpha. In addition, Phycarine increased NK cell-mediated killing of tumor cells both in vitro and in vivo while acting via complement receptor type 3 (CR3) receptors.

DNA array analysis of altered gene expression in human leukocytes stimulated with soluble and particulate forms of Candida cell wall β-glucan

We previously reported that 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). We found that OX-CA and CSBG showed significantly different levels of activity toward leukocytes. Here, we have used cDNA microarrays to analyze the mRNA expression of 1176 genes in PBMCs stimulated with Candida cell wall glucan and considered the difference in the activation mechanism of OX-CA and CSBG. Total mRNA showed a significant change for 147 out of 1176 arrayed genes on stimulation with OX-CA and CSBG for 4 h. Among those genes, 62 were common, 26 were OX-CA-specific and 59 were CSBG-specific. Many of these up-regulated genes encode effectors with well-characterized proinflammatory properties. The expression of genes related with signal transduction differed in the particulate and soluble glucans derived from C. albicans having exactly the same primary structure. This fact suggested that each glucan induced specific biological activity through a different activation mechanism. This study using cDNA microarrays to analyze a broad spectrum of mRNA expression provides information on the biological activity of Candida cell wall glucan as a potential pathogenic factor.

Potential growth inhibitory effect of maitake D-fraction on canine cancer cells

The postulated anticancer effect of D-fraction, the bioactive extract of maitake mushroom, on three types (CF33, CF21, and CL-1) of canine cancer cells was evaluated. The effect of D-fraction on several human cancer cells was also investigated. The effect of other beta-glucan products was likewise examined. D-fraction was highly effective on the canine cancer cells, either potently inhibiting cell growth or directly killing cells. Similar effects were also demonstrated in certain human cancer cells. However, other beta-glucan products relevant to D-fraction had no such effects on canine cancer cells. Therefore, D-fraction is a potent natural agent that could be useful in treating canine cancers as well as other veterinary cancers.

Diet containing fungal (1-->3)-beta-D-glucan derivative exhibits protective effects against DNA lesions induced in freshly isolated rat cells

Dietary effect of water-soluble derivative - carboxymethyl chitin-glucan (CM-CG) on the level of DNA lesions induced by hydrogen peroxide (H2O2) was examined in ex vivo experiments. Lymphocytes, testicular cells, alveolar macrophages and epithelial II cells were isolated from Sprague Dawley rats fed a common or CM-CG enriched diet (200 mg/kg of body weight) during 21 days. Freshly isolated cells were in in vitro conditions exposed to H2O2 and the levels of DNA breaks were evaluated by single cell gel electrophoresis. A dose-dependent increase of DNA breaks was observed after treatment with hydrogen peroxide in all studied cell types. The levels of DNA breaks in cells isolated from CM-CG supplemented animals were lower compared to the levels of DNA breaks in cells isolated from animals fed a common diet. Intake of CM-CG enriched diet did not increase the level of DNA damage in different kinds of freshly isolated rat cells and equipped the cells with resistance to the treatment with hydrogen peroxide.

[Biologically active compounds of edible mushrooms and their beneficial impact on health]

Edible mushrooms are valuable a source of biologically active compounds. Some are used in the prophylaxis and therapy of such diseases as cancer and cardiovascular disease. Their antitumor mechanism is complex. The biologically active substances in mushrooms decrease DNA damage, reduce carcinogen concentrations and their activation, inhibit the growth of cancer cells by scavenging free radicals, stimulate the immune system, and induce tumor cell apoptosis. The stimulation of the immune system by the biologically active compounds in edible mushrooms protects against cold, flu, infections, well as AIDS by inhibition of viral replication. Mushrooms contain effective substances which decrease the LDL fraction of cholesterol in blood. They also prevent the accumulation of serum triaclyglycerols, thus decreasing the risk of developing cardiovascular disease. The therapeutic properties of mushrooms result from the specific polysaccharides, such as beta-glucans and chitosans, that are present in the fructification of fungi.