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

Effect of 1,3-Beta Glucans Dietary Addition on the Growth, Intestinal Histology, Blood Biochemical Parameters, Immune Response, and Immune Expression of CD3 and CD20 in Broiler Chickens

This experiment evaluated the impact of the dietary addition of 1,3-β-glucans (GLU) on broiler chickens’ growth, intestinal histology, blood biochemical parameters, and immunity. Two hundred three-day-old male broilers (Ross 308) (97.93 ± 0.19 g/chick) were randomly assigned into four treatments with five replicates, each containing ten birds, in a complete randomized design. The four treatments were formulated with 0, 50, 100, and 150 mg 1,3-β-glucans kg−1 in broiler chicken diets. During the study, no significant impacts (p > 0.05) were observed in weight gain and feed conversion ratio (FCR) between treatment groups. Based on the results of total body weight gain and FCR, the optimal level of 1,3-β-glucan is 120 mg Kg−1. The intestinal histomorphology was improved by GLU supplementation, as indicated by increased villi height and villi height to crypt depth ratio (p < 0.01). All levels of supplemental β-1,3 glucan decreased the serum total cholesterol (TC), triglyceride levels, and low-density lipoprotein cholesterol (LDL-C) (p < 0.05). The serum levels of growth hormones (GH), triiodothyronine (T3), and thyroxine (T4) were increased in GLU-supplemented groups (p < 0.05). The serum immune indices (lysozyme activity, interleukin 10 (IL10), complement 3 (C3), and total protein levels) were increased in the GLU-supplemented groups (p < 0.05). Dietary GLU up-regulated the immunoexpression of CD3 (T-cell marker) and CD20 (B-cell marker) in the spleen of birds (p < 0.01). It can be concluded that 1,3-β-glucan can be added to broiler chicken diets for improving the development and integrity of the intestine and enhancing the bird’s immune status. The optimal level for 1,3-β-glucan dietary supplementation was 120 mg Kg−1. Dietary 1,3-β-glucan has a hypolipidemic effect and improves the hormonal profile of birds without affecting their growth rate.

Oral administration of botryosphaeran [(1 → 3)(1 → 6)-β-d-glucan] reduces inflammation through modulation of leukocytes and has limited effect on inflammatory nociception

Several biological activities of the fungal exopolysaccharide (1 → 3)(1 → 6)-β-d-glucan (botryosphaeran) have been described in the literature, but its effects on inflammation have not been evaluated. This study aimed to investigate the action of botryosphaeran on experimental mice models of carrageenan-induced acute pleurisy and acute paw edema, and complete Freund's adjuvant-induced persistent paw edema. All botryosphaeran doses tested (1.0, 2.5, 5.0, and 10.0 mg/kg birth weight [b.w.], orally administered) reduced leukocyte recruitment, nitric oxide (NO) levels, and protein extravasation in the pleural cavity. Botryosphaeran (5 mg/kg b.w.) did not diminish edema and mechanical hyperalgesia in the paw within 4 h; however, cold allodynia was alleviated within the first 2 h. In the persistent paw inflammation model, the effects of daily oral administration of botryosphaeran (5 mg/kg b.w.) were evaluated over 3 and 7 days. The fungal β-glucan significantly reduced the levels of the cytokines, tumor necrosis factor(TNF)-α, interleukin (IL)-6), and IL-10, in the paw homogenates in both protocols, while paw edema and the levels of advanced oxidation protein products (AOPP) only diminished on Day 7. No effect in mechanical hyperalgesia was observed. Oral treatment for 3 or 7 days also decreased the plasma levels of NO, AOPP, TNF-α, and IL-10. On Day 7, the number of leukocytes in the blood was also reduced by this treatment. Importantly, botryosphaeran did not induce inflammation in mice when administered alone over 7 days. This study demonstrated the anti-inflammatory and antinociceptive potential of botryosphaeran in these experimental models, making this fungal β-glucan a new possibility for complementary treating acute and chronic inflammation.

Immune-enhancing effect of water-soluble beta-glucan derived from enzymatic hydrolysis of yeast glucan

Immunostimulants play an important role in the treatment of immunodeficiency. Macrophages are the first line in our immune defense system and play a critical role in the immune response. Therefore, finding new and better substances to induce an immune response by activating macrophages is an attractive research topic, especially in the fields of immunopharmacology and cancer prevention. Keratinocytes actively crosstalk with immune cells during wound repair, so enhancing the function of keratinocytes is also an important part of improving immunity. Beta-glucans are naturally occurring polysaccharides, consisting of d-glucose monomers linked by beta-glycosidic bonds. Several studies have investigated the immunomodulatory effects of beta-glucan, such as its anti-inflammatory and antibacterial properties. However, the use of yeast cell wall glucan has been limited because it is not soluble in water. In this study, we produced low-molecular-weight water-soluble yeast glucan (WSY glucan) and confirmed various aspects of its immune-enhancing effect. The structure of the beta-(1→3) and (1→6) bonds of WSY glucan were confirmed by nuclear magnetic resonance spectroscopy (¹H-NMR) analysis. Our results showed that treatment with WSY glucan significantly and dose-dependently induced the production of inflammatory mediators (prostaglandin E₂ (PGE₂) and nitric oxide (NO)) and pro-inflammatory cytokines (tumor necrosis factor (TNF)-α and interleukin (IL)-6) in macrophages. In addition, WSY glucan treatment showed changes in the morphological structure of the macrophages and promoted phagocytic activity of the macrophages and wound healing in keratinocytes. Based on these results, WSY glucan is considered as a potential candidate for the treatment of diseases related to the weakening of the immune system without the limitation of insolubility.

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Soluble low-molecular-weight beta-glucan, WSY-glucan, was produced through enzymatic hydrolysis.

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WSY glucan significantly and dose-dependently induced the production of pro-inflammatory cytokines (TNF-α and IL-6) and inflammatory mediators (NO and prostaglandin E₂) in macrophages.

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WSY glucan treatment showed changes in the morphological structure of the macrophages and promoted phagocytic activity of the macrophages and wound healing in keratinocytes.

Evaluation of the biological activities of β-glucan isolated from Lentinula edodes

Lentinula edodes (shiitake) is an edible mushroom that contains many constituents and β-glucan is considered a major polysaccharide. This study, therefore, aimed to characterize β-glucan and evaluate its activities. Fresh fruit bodies of L. edodes were used for β-glucan extraction and followed by analyses via Fourier transform infrared, Nuclear magnetic resonance, and High Performance Liquid Chromatography confirming its characteristic structure. For evaluating biological activities of β-glucan, different concentrations (0.1-3.5 mg ml^-1 ) were assessed. The optimal dose was 3.5 mg ml^-1 that showed the highest scavenging radical ability (75.3%) confirms antioxidant activity, strong inhibition of the peroxyl radical (80.9%) to inhibit lipid peroxidation, elevation the inhibition percentage of both α-amylase (73.4%) and α-glucosidase (70.3%) indicates the antidiabetic properties, and highest AFB1 reduction (88%) which ensured the aflatoxin-detoxifying ability. In addition, antifungal activity of β-glucan was evaluated to inhibit sporulation process in Aspergillus niger and recorded with minimum inhibitory concentration of 2.5 mg ml^-1 and minimum fungicidal concentration of 3 mg ml^-1 . In a dose-dependent manner, higher concentration of β-glucan affects viability of tumor cells concomitant induces potent anti-cancer immune responses and inhibited the activity of topoisomerase I which are considered an important target for cancer chemotherapy. Therefore, L. edodes-β-glucan has the potential to act as a suggestive agent for antioxidant, antidiabetic, antifungal activity, and aflatoxin detoxification.

The Possible Protective Role of Barley Seeds on the Spleen after Administration of Glucocorticoids in Adult Albino Rats: A Histological and Immunohistochemical Study

Background:

Glucocorticoids (GCs) are the main treatment strategy in many autoimmune disease and inflammatory diseases; however, they have immunosuppressive effect on many organs. The barley seeds contain many antioxidant compounds, which may improve the antioxidant status and related physiological functions. Our aim in this work is to evaluate the possible protective role of barley seeds on some immune cells in the spleen against immunosuppressive effect of GCs in adult albino rats.

Materials and Methods:

Forty-five adult albino rats were equally divided into 3 groups. Group I: normal vehicle control (n = 15), Group II: steroid-treated animals (n = 15), and Group III: steroid/barley-treated group (n = 15). Specimens from spleen were processed for light and electron microscopy.

Results:

In steroid-treated group, the histological changes in white and red pulp were in the form of loss of architecture and wide empty spaces among the cells. Most of the cells showed degenerative change, dilatation of blood sinusoids, and deposition of fibrinoid material among the cells of the RP. However, multiple lysosomal bodies were observed in both dendritic and macrophage cells. These changes are improved in steroid/barley-treated group in the form of increasing the number and size of the lymphatic follicles. Most of the splenic cells regained normal structure. Dendritic cell marker CD86 and macrophage marker CD68 expression are increased.

Conclusion:

Barley protects the spleen tissues from steroid-induced structural changes; this could be mediated through its antioxidant effects, so barely is recommended as a healthy diet in patients consuming steroids.

Optimization of Polysaccharide Production from Cordyceps militaris by Solid-State Fermentation on Rice and Its Antioxidant Activities

Polysaccharides are an important class of bioactive components of medical mushroom and herbs and are now used as natural drugs or dietary supplements on a global scale. In this paper, we aimed to increase the polysaccharide production of Cordyceps militaris and the antioxidant activities of fermented rice by solid-state fermentation. The media components and culture condition were optimized by orthogonal design and mono-factor tests using rice as the raw material. The optimal media consisted of (g/L): rice (50), fructose (7), glycerin (7), peptone (1), MgCl₂ (0.11), VB₁ (0.05), VB₂ (0.05), CaCl₂ (1.5), corn bran (6), and a water-materials ratio of 100%. The fermentation condition was as follows: inoculum volume of 5.5% (v/w), rice weight of 50 g in one bowl with a diameter of 120 mm and a depth of 90 mm, incubation temperature of 26 °C, and incubation time of seven days. Under the optimized condition, the maximal C. militaris polysaccharide content and free radical scavenging ratio were 68.3 mg/g dry substrate and 98.9%, respectively. This study provides a new strategy for the production of healthy food from traditional food.

Solubilized melanin suppresses macrophage function

Melanin‐producing Cryptococcus and Aspergillus are highly invasive and can suppress or escape the immune system of the host. Since non‐melanin‐producing strains do not affect the immune system, melanin may play a role in immune system suppression. Artificial melanin synthesized using conventional methods is insoluble, making structural and functional analysis of this chemical difficult. In this study, we describe a melanin solubilization method based on polymerization of homogentisic acid (solubilizing component) and an equivalent amount of L‐DOPA in the presence of laccase. In addition, we investigated the effect of melanin on the immune system. Homogentisic acid and L‐DOPA mixed melanin (HALD), the synthetic solubilized melanin, did not exert a cytotoxic effect on mouse macrophages. HALD suppressed cytokine and reactive oxygen species production by macrophages when they were stimulated by fungal components. HALD also suppressed the phagocytosis of fungal components by macrophages. These results suggest that HALD can suppress the function of macrophages without causing cytotoxicity.

Effect of dietary β-glucan on growth, survival and regulation of immune processes in rainbow trout (Oncorhynchus mykiss) infected by Aeromonas salmonicida

The present study evaluated the effects of dietary β-glucan (0, 0.05%, 0.1%, and 0.2%) on growth performance after 42 days of feeding. Thereafter, rainbow trout (Oncorhynchus mykiss) were infected with Aeromonas salmonicida, and survival rates as well as the regulating processes of stress- and immune-related factors were analyzed. In general, higher dietary β-glucan levels obviously improved specific growth rate (SGR), weight gain (WG) and feed efficiency (FE) (P ≤ 0.05). Survival rates in β-glucan groups increased significantly compared with the control group after A. salmonicida infection (P ≤ 0.05). Serum total superoxide dimutase (T-SOD), peroxidase (POD) as well as catalase (CAT) activities, and their mRNA expressions in the head kidney of fish in the β-glucan groups generally increased to higher levels after infection, and more quickly, compared with in the control group. Serum lysozyme (LSZ) and its expression in the head kidney in β-glucan groups reached a higher peak earlier than in the control group. Serum glutamic oxalacetic transaminase (GOT) and glutamic pyruvic transaminase (GPT) levels in the β-glucan groups were significantly lower than in the control group (P ≤ 0.05). The peak of heat shock protein 70 (HSP70) expression in the 0.2% β-glucan group was higher and occurred earlier than in other groups (P ≤ 0.05). These results confirm that 0.1% and 0.2% dietary β-glucan are beneficial for promoting growth in rainbow trout and enhancing resistance against A. salmonicida. Furthermore, β-glucan could play an important role in regulating stress- and immune-related factors in rainbow trout to more quickly fight against bacterial infection.

Lung cancer and β-glucans: review of potential therapeutic applications

The potential of natural substances with immunotherapeutic properties has long been studied. β-glucans, a cell wall component of certain bacteria and fungi, potentiate the immune system against microbes and toxic substances. Moreover, β-glucans are known to exhibit direct anticancer effects and can suppress cancer proliferation through immunomodulatory pathways. Mortality of lung cancer has been alarmingly increasingly worldwide; therefore, treatment of lung cancer is an urgent necessity. Numerous researchers are now dedicated to using β-glucans as a therapy for lung cancer. In the present attempt, we have reviewed the studies addressing therapeutic effects of β-glucans in primary and metastatic lung cancer published in the time period of 1991-2016.

The effects of feeding immunostimulant β-glucan on the immune response of Pangasianodon hypophthalmus

Immunostimulants are food additives used by the aquaculture industry to enhance the immune response of fish, and although β-glucans are now commonly used for this purpose in aquaculture, little is known about their effects on the immune response of Pangasianodon hypophthalmus. Thus, a variety of immune parameters (e.g. phagocytosis, respiratory burst, lysozyme, complement, peroxidase, total protein, total anti-protease, total IgM, natural antibody titres, and specific IgM titres) was examined in this species after feeding fish with a basal control diet or diets supplemented with 0.05, 0.1, or 0.2 g/kg fungal-derived β-glucan or 0.1% commercial yeast-derived β-glucan, as a positive control diet, for a period of four weeks. The effect of the glucans on disease resistance was then evaluated by experimentally infecting the fish with Edwardsiella ictaluri by immersion and mortalities monitored for 14 days. Samples were collected from fish for analysis at 0, 1, 3, 7, 14, 21 and 28 days post-feeding (dpf), and also at 14 days post infection (dpi). The lowest dose of fungal-derived β-glucan (0.05%) appeared insufficient to effectively stimulate the immune response of the fish, while those fed with the two highest levels of fungal-derived β-glucan had enhanced immune responses compared to the control group. Significantly elevated levels of respiratory burst activity on all days examined (P < 0.05) and lysozyme activity on 7 dpf were found in the group fed 0.2% fungal-derived β-glucan, while plasma anti-protease activity was significantly enhanced (P < 0.05) by 21 dpf, natural antibody titres by 3 dpf and complement activity by 7 dpf and also at 14 dpi in the group fed 0.1% fungal-derived β-glucan. No statistical differences was seen in the level of mortalities between the dietary groups, although the group fed with the control diet had the highest level of mortalities and the groups fed with commercial yeast-derived β-glucan and 0.2% fungal-derived β-glucan the lowest.

Mechanism of Enhanced Hematopoietic Response by Soluble β-Glucan SCG in Cyclophosphamide-Treated Mice

SCG is a major 6-branched 1,3-beta-D-glucan in Sparassis crispa Fr. SCG shows antitumor activity and also enhances the hematopoietic response in cyclophosphamide (CY)-treated mice. In the present study, the molecular mechanism of the enhancement of the hematopoietic response was investigated. The levels of interferon-(IFN-)gamma, tumor necrosis factor-(TNF-)alpha, granulocyte-macrophage-colony stimulating factor (GM-CSF), interleukin-(IL-) 6 and IL-12p70 were significantly increased by SCG in CY-treated mice. GM-CSF production in the splenocytes from the CY-treated mice was higher than that in normal mice regardless of SCG stimulation. Neutralizing GM-CSF significantly inhibited the induction of IFN-gamma, TNF-alpha and IL-12p70 by SCG. The level of cytokine induction by SCG was regulated by the amount of endogenous GM-CSF produced in response to CY treatment in a dose-dependent manner. The expression of beta-glucan receptors, such as CR3 and dectin-1, was up-regulated by CY treatment. Blocking dectin-1 significantly inhibited the induction of TNF-alpha and IL-12p70 production by SCG. Taken together, these results suggest that the key factors in the cytokine induction in CY-treated mice were the enhanced levels of both endogenous GM-CSF production and dectin-1 expression.

Immunostimulatory properties and antitumor activities of glucans (Review)

New foods and natural biological modulators have recently become of scientific interest in the investigation of the value of traditional medical therapeutics. Glucans have an important part in this renewed interest. These fungal wall components are claimed to be useful for various medical purposes and they are obtained from medicinal mushrooms commonly used in traditional Oriental medicine. The immunotherapeutic properties of fungi extracts have been reported, including the enhancement of anticancer immunity responses. These properties are principally related to the stimulation of cells of the innate immune system. The discovery of specific receptors for glucans on dendritic cells (dectin-1), as well as interactions with other receptors, mainly expressed by innate immune cells (e.g., Toll-like receptors, complement receptor-3), have raised new attention toward these products as suitable therapeutic agents. We briefly review the characteristics of the glucans from mycelial walls as modulators of the immunity and their possible use as antitumor treatments.

Beta-glucan: an ideal immunostimulant in aquaculture (a review)

The major hindrance in the development and sustainability of aquaculture industry is the occurrence of various diseases in the farming systems. Today, preventive and management measures are central concern to overcome such outbreak of diseases. Immunostimulants are considered as an effective tool for enhancing immune status of cultured organisms. Among different immunostimulants used in aquaculture practices, β-glucan is one of the promising immunostimulant, which is a homopolysaccharide of glucose molecule linked by the glycoside bond. It forms the major constituents of cell wall of some plants, fungi, bacteria, mushroom, yeast, and seaweeds. Major attention on β-glucan was captivated with the gain in knowledge on its receptors and the mechanism of action. The receptor present inside the animal body recognizes and binds to β-glucan, which in turn renders the animal with high resistance and enhanced immune response. This review highlights β-glucan as an immunostimulant, its effective dosages, and route of administration and furthermore provides an outline on role of β-glucan in enhancing growth, survival, and protection against infectious pathogens pertaining to fishes and shellfishes. Study also summarizes the effect of β-glucan on its receptors, recognition of proteins, immune-related enzymes, immune-related gene expression and their mechanisms of action.

Applications of polymeric adjuvants in studying autoimmune responses and vaccination against infectious diseases

Polymers as an adjuvant are capable of enhancing the vaccine potential against various infectious diseases and also are being used to study the actual autoimmune responses using self-antigen(s) without involving any major immune deviation. Several natural polysaccharides and their derivatives originating from microbes and plants have been tested for their adjuvant potential. Similarly, numerous synthetic polymers including polyelectrolytes, polyesters, polyanhydrides, non-ionic block copolymers and external stimuli responsive polymers have demonstrated adjuvant capacity using different antigens. Adjuvant potential of these polymers mainly depends on their solubility, molecular weight, degree of branching and the conformation of polymeric backbone. These polymers have the ability not only to activate humoral but also cellular immune responses in the host. The depot effect, which involves slow release of antigen over a long duration of time, using different forms (particulate, solution and gel) of polymers, and enhances the co-stimulatory signals for optimal immune activation, is the underlying principle of their adjuvant properties. Possibly, polymers may also interact and activate various toll-like receptors and inflammasomes, thus involving several innate immune system players in the ensuing immune response. Biocompatibility, biodegradability, easy production and purification, and non-toxic properties of most of the polymers make them attractive candidates for substituting conventional adjuvants that have undesirable effects in the host.

Gut Colonization by Candida albicans Inhibits the Induction of Humoral Immune Tolerance to Dietary Antigen in BALB/c Mice

We previously observed that gut colonization by Candida albicans promoted serum antibody response to orally administered ovalbumin in mice. We therefore postulated that C. albicans affects oral tolerance induction. The present study tested this idea. BALB/c mice were intragastrically administered with either C. albicans (1 × 10⁷) or vehicle, and the colonization was confirmed by weekly fecal cultures. Mice were further divided into two subgroups and intragastrically administered with either ovalbumin (20 mg) or vehicle for five consecutive days. Thereafter, all mice were intraperitoneally immunized with ovalbumin in alum. In mice without C. albicans inoculation, ovalbumin feeding prior to immunization significantly suppressed the increase in ovalbumin-specific IgE, IgG1 and IgG2a in sera, suggesting oral tolerance induction. In C. albicans-inoculated mice, however, the antibody levels were the same between ovalbumin- and vehicle-fed mice. In contrast, ovalbumin feeding significantly suppressed cellular immune responses, as evidenced by reduced proliferation of splenocytes restimulated by ovalbumin ex vivo, in both C. albicans-inoculated and uninoculated mice. Ex vivo supplementation with neither heat-killed C. albicans nor the culture supernatant of C. albicans enhanced the production of ovalbumin-specific IgG1 in splenocytes restimulated by the antigen. These results suggest that gut colonization by C. albicans inhibits the induction of humoral immune tolerance to dietary antigen in mice, whereas C. albicans may not directly promote antibody production. We therefore propose that C. albicans gut colonization could be a risk factor for triggering food allergy in susceptible individuals.

Effects of mannan oligosaccharide on cytokine secretions by porcine alveolar macrophages and serum cytokine concentrations in nursery pigs

This study explored the hypothesis that mannan oligosaccharide (MOS) acts to reduce systemic inflammation in pigs by evaluating cytokine production of alveolar macrophages (AM) and serum cytokine concentrations. A total of 160 pigs were fed diets containing 0.2 or 0.4% MOS for 2 or 4 wk postweaning compared with control diets without MOS. Dietary MOS did not affect the serum concentration of tumor necrosis factor (TNF)-α and tended (P = 0.081) to increase that of IL-10. These cytokine concentrations also changed over time (P < 0.001). After 2-wk feeding of the control or MOS diets, AM were collected and stimulated ex vivo with lipopolysaccharide (LPS) or polyinosinic:polycytidylic acid (PLIC) as infection models. The LPS-stimulated AM from MOS-fed pigs (n = 12) secreted less TNF-α (P < 0.001) and more IL-10 (P = 0.026) than those from control-fed pigs (n = 6). However, dietary MOS had less effect on ex vivo TNF-α and IL-10 production by PLIC-stimulated AM (P = 0.091 and P > 0.10, respectively. Further, effects of MOS were examined in 4 in vitro experiments. In Exp. 1 (n = 4 pigs), MOS and mannan-rich fraction (MRF), when added to AM cultures, were able to increase TNF-α production. This direct effect of MOS was not due to endotoxin contamination as verified in Exp. 2 (n = 6 pigs) using polymyxin B, an inhibitor of LPS activation of toll-like receptor 4. Polymyxin B inhibited production of TNF-α by AM after treatment with LPS (P < 0.001), but not after treatment with MOS in the absence of LPS (P > 0.70). In Exp. 3 (n = 6 pigs), when MOS was directly applied in vitro, the pattern of cytokine production by LPS-activated AM was similar to that observed ex vivo, as MOS suppressed LPS-induced TNF-α (P < 0.001) and enhanced LPS-induced IL-10 (P = 0.028). In Exp. 4 (n = 6 pigs), when MRF replaced MOS, AM-produced TNF-α induced by LPS or PLIC was suppressed by MRF (P = 0.015 or P < 0.001, respectively). These data establish that MOS and MRF suppress LPS-induced TNF-α secretions by AM. Generally, the study suggests that MOS may be a potent immunomodulator because it directly activates AM to secrete TNF-α and alters the cytokine responses of bacterial endotoxin-induced AM in both ex vivo and in vitro systems. In particular, feeding MOS to pigs for 2 wk reduces TNF-α and increases IL-10 concentrations after ex vivo treatment of AM with LPS. These immunomodulatory properties of MOS may have important implications for both host defense and avoidance of harmful overstimulation of the immune system.

Effects of Sophy β-glucan on growth performance, carcass traits, meat composition, and immunological responses of Peking ducks

The response of Peking ducks to supplements of Sophy β-glucan was studied. A total of 160 healthy 1-d-old mixed-sex ducklings were randomly allocated to 3 groups: Sophy β-glucan (n = 80), bacitracin zinc (n = 40), and control (n = 40), which received the same antibiotics-deficient diet supplemented with 1% β-glucan, 5% bacitracin zinc, or nothing, respectively. During 2 mo of the study, growth performance, carcass composition, and meat quality of Peking ducks were evaluated. Additionally, a separate immunological study was conducted with a total of 105 healthy male Peking ducks in 7 groups (n = 15) and immunized with different doses of β-glucan (0, 0.5, 2.5, 12.5, and 62.5 μg/duck) and BSA (200 μg/duck). Blood was taken for detection of anti-BSA-IgG antibody and peripheral blood mononuclear cells proliferation assays. Groups subjected to different dietary treatments showed almost no differences in growth performance and slaughter traits except breast muscle percentage and intestinal length. These 2 indicators were significantly higher in the bacitracin zinc group than in the control and β-glucan groups (P < 0.05). Similarly, chemical compositions, fatty acids, and amino acids of breast muscle were not significantly influenced by the diet. Ducks immunized with Sophy β-glucan did not have enhanced level of anti-BSA-IgG antibodies but had significant peripheral blood mononuclear cells proliferation compared with unchallenged ducks (P < 0.01). With an increase in the glucan concentration, the proliferative responses approximately linearly increased. These findings indicate that 1% Sophy glucan did not improve duck growth performance, carcass composition, and meat quality significantly under the conditions of the present experiment and mainly had regulatory or enhancing properties on poultry nonspecific cellular immunity.

Immunostimulatory properties of a polysaccharide isolated from Astraeus hygrometricus

Mushrooms have been used as food and for therapeutic purpose for decades, and various compounds derived from these have potential biological activities. Application of such agents of natural origin is vital with relevance to an increase in diseases involving immune dysfunction, cancer, and autoimmune conditions in recent years. These compounds belong mainly to polysaccharides, especially beta-D-glucan, glycopeptide/protein complexes, proteoglycans, proteins, and triterpenoids. Among these compounds, polysaccharides and their peptide/protein derivates have extremely important roles in immunomodulating activities. The present study aims to explore the immunomodulatory properties of polysaccharide isolated from the mushroom Astraeus hygrometricus. The polysaccharide isolated by hot alkaline extraction and chromatography was designated as AE2 and studied for its immunostimulatory potential in vivo in a murine model. Macrophages from treated mice showed higher production of nitric oxide and interleukin-1 and also exhibited an increased phagocytic potential. It also enhanced natural killer cell activation and proliferation of splenocytes with an increase in the T-helper (Th) 1 cytokine level of splenocyte culture supernatant. The cytokine level in serum also indicated a Th1 skew. The observed activities were associated with no general toxicity to the organism. The findings will be helpful in considering A. hygrometricus as a potential source of an immunomodulator and in designing further studies to understand its mode of action on immune system.

Granulocyte macrophage colony-stimulating factor is required for cytokine induction by a highly 6-branched 1,3-β-D-glucan from Aureobasidium pullulans in mouse-derived splenocytes

We have previously obtained and elucidated the precise structure of a highly branched 1,3-β-D-glucan (with 6-monoglucopyranosyl side chains), Aureobasidium pullulans-fermented β-D-glucan (AP-FBG), from the fungus A. pullulans. However, the mechanism(s) of the effects of AP-FBG on in vitro mouse primary cells have not been analyzed in detail. Herein, we report that the induction of cytokines by AP-FBG was dependent on the existence of a granulocyte macrophage colony-stimulating factor (GM-CSF); this is similar way to be a typical 1,3-β-D-glucan from Sparassis crispa (SCG), which is a 1,3-β-D-glucopyranosyl backbone with single 1,6-β-D-glucopyranosyl side branching units every three residues. In other words, the production of cytokines in DBA/2-mouse-derived splenocytes by AP-FBG was completely hampered by an anti-GM-CSF neutralizing monoclonal antibody. Furthermore, the addition of exogenous GM-CSF to C57BL/6-derived splenocytes, which are less sensitive to AP-FBG, induced the production of cytokines by AP-FBG. Therefore, GM-CSF is indispensable for the induction of cytokines by AP-FBG in mouse-derived splenocytes. This finding has provided a new insight into our understanding of the actions of β-D-glucan but will also aid in the design and development of more effective β-D-glucan agents.

Candida soluble cell wall beta-glucan facilitates ovalbumin-induced allergic airway inflammation in mice: Possible role of antigen-presenting cells

BACKGROUND

Although fungi have been implicated as initiating/deteriorating factors for allergic asthma, their contributing components have not been fully elucidated. We previously isolated soluble beta-glucan from Candida albicans (CSBG) (Ohno et al., 2007). In the present study, the effects of CSBG exposure on airway immunopathology in the presence or absence of other immunogenic allergen was investigated in vivo, and their cellular mechanisms were analyzed both in vivo and in vitro.

METHODS

In vivo, ICR mice were divided into 4 experimental groups: vehicle, CSBG (25 microg/animal), ovalbumin (OVA: 2 microg/animal), and CSBG + OVA were repeatedly administered intratracheally. The bronchoalveolar lavage cellular profile, lung histology, levels of cytokines and chemokines in the lung homogenates, the expression pattern of antigen-presenting cell (APC)-related molecules in the lung digests, and serum immunoglobulin values were studied. In vitro, the impacts of CSBG (0-12.5 microg/ml) on the phenotype and function of immune cells such as splenocytes and bone marrow-derived dendritic cells (BMDCs) were evaluated in terms of cell proliferation, the surface expression of APC-related molecules, and OVA-mediated T-cell proliferating activity.

RESULTS

In vivo, repeated pulmonary exposure to CSBG induced neutrophilic airway inflammation in the absence of OVA, and markedly exacerbated OVA-related eosinophilic airway inflammation with mucus metaplasia in mice, which was concomitant with the amplified lung expression of Th2 cytokines and IL-17A and chemokines related to allergic response. Exposure to CSBG plus OVA increased the number of cells bearing MHC class II with or without CD80 in the lung compared to that of others. In vitro, CSBG significantly augmented splenocyte proliferation in the presence or absence of OVA. Further, CSBG increased the expression of APC-related molecules such as CD80, CD86, and DEC205 on BMDCs and amplified OVA-mediated T-cell proliferation through BMDCs.

CONCLUSION

CSBG potentiates allergic airway inflammation with maladaptive Th immunity, and this potentiation was associated with the enhanced activation of APCs including DC.

Rapid decrease of anti-beta-glucan antibody as an indicator for early diagnosis of carinii pneumonitis and deep mycotic infections following immunosuppressive therapy in antineutrophil cytoplasmic antibody-associated vasculitis

Deep mycosis (aspergillus pneumonia (AsP)) and carinii pneumonitis (PCP) are complications of immunosuppressive treatment for antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV). The objective was to clarify the clinical significance of plasma titer of antibody against beta-glucans (anti-BG antibody) as a predictor of complications such as AsP or PCP and the prognosis of patients. Enzyme-linked immunosorbent assay was used to measure the plasma titer of antibodies against beta-glucans (BG) from Candida albicans in 22 healthy subjects and 52 patients with various stages of AAV. The mean plasma titer of the anti-BG antibody was 2,677 +/- 1,686 U in healthy subjects, 691 +/- 522 U in patients with untreated active vasculitis (n = 14), and 547 +/- 416 U in patients soon after immunosuppressive treatment (n = 24). Healthy subjects had significantly higher antibody titers than the other two groups (P < 0.05). Repeated measurements over the clinical course of AAV revealed an increase during remission to 1,180 +/- 130 U (n = 11), while there was a significant rapid decrease to 369 +/- 441 U (P < 0.01) concomitantly with elevation in plasma C-reactive protein and BG levels in patients with AAV that had AsP or PCP infection. Antifungal therapy resulted in a rapid rise of anti-BG antibody titer. Experiments in mice suggested that the anti-BG antibody neutralizes BG. Rapid decrease of the anti-BG antibody titer may be a useful indicator for diagnosis of the presence of AsP or PCP and for estimating the prognosis of patients with these opportunistic infections during immunosuppressive treatment of AAV.

Potentiation of histamine release by Microfungal (1-->3)- and (1-->6)-beta-D-glucans

(1-->3)-beta-D-Glucans, a cell wall component in most microfungi, are suggested to play a role in the development of respiratory and general symptoms in organic dust-related diseases. The mechanisms by which they induce these effects are, however, not clear. In the present study, mediator release and its potentiation by the (1-->3)-beta-D-glucan as well as by the (1-->6)-beta-D-glucan found in yeast and other fungi were therefore examined. Blood leucocytes from healthy volunteers and from patients allergic to house dust mite were incubated with (1-->3)-beta-D-glucans with increasing 1,6-branchings: curdlan [a linear (1-->3)-beta-D-glucan], laminarin and scleroglucan, and furthermore with pustulan, a linear (1-->6)-beta-D-glucan. Histamine release was not observed on exposure to the glucans only, but in the presence of anti-immunoglobulin E (IgE) antibody or specific antigens, all the glucans investigated led to an enhancement of the IgE-mediated histamine release. The glucans induced a significant potentiation of the mediator release when present at concentrations in the range of 2-5 x 10(-5) M. These results suggest that (1-->3)-beta-D-glucan as well as (1-->6)-beta-D-glucan aggravates IgE-mediated histamine release. Knowledge concerning the effects of glucans on immune responses may be of importance for understanding and treating inflammatory and allergic diseases.

beta-Glucans in promoting health: prevention against mutation and cancer

The polysaccharides beta-glucans occur as a principal component of the cellular walls. Some microorganisms, such as yeast and mushrooms, and also cereals such as oats and barley, are of economic interest because they contain large amounts of beta-glucans. These substances stimulate the immune system, modulating humoral and cellular immunity, and thereby have beneficial effect in fighting infections (bacterial, viral, fungal and parasitic). beta-Glucans also exhibit hypocholesterolemic and anticoagulant properties. Recently, they have been demonstrated to be anti-cytotoxic, antimutagenic and anti-tumorogenic, making them promising candidate as pharmacological promoters of health.

Cell Wall .BETA.-Glucan Derived from Candida albicans Acts as a Trigger for Autoimmune Arthritis in SKG Mice

SKG mice are a recently established experimental model for rheumatoid arthritis (RA). Although they spontaneously develop chronic autoimmune arthritis under conventional conditions, SKG mice failed to develop chronic arthritis in a strictly controlled specific pathogen-free (SPF) environment. Beta-glucan (BG) from Laminaria digitata, laminarin (LAM), induced arthritis under SPF conditions, thus BG would be a pathogenic factor for arthritis in SKG mice. Therefore, we prepared BG from Candida albicans, a pathogenic fungus and investigated whether BG from C. albicans induced arthritis in SKG mice under SPF conditions. SKG mice were injected intraperitoneally with particulate BG (oxidative-Candida albicans (OX-CA)), soluble BG (Candida soluble beta-glucan (CSBG)) from C. albicans and LAM as a positive control. In addition, schizophyllan (SPG) from Schizophyllum commune or Mycobacterium whole cells were injected into SKG mice to induce arthritis. Mice injected with OX-CA, CSBG and SPG had more severe arthritis than with LAM, and whole Mycobacterium cells. IL-6 concentration in sera from SKG mice injected with OX-CA or CSBG was high, whereas not detected in sera from mice treated with LAM. In histological analysis, infiltration of inflammatory cells was observed in SKG mice injected with BG. These results suggest that fungal infection may be a factor to induce and exacerbate autoimmune diseases such as RA.

Macrophage activation and nitric oxide production by water soluble components of Hericium erinaceum

Hericium erinaceum is a medicinal and edible mushroom with anti-microbial and anti-cancer activities. To evaluate the immunoregulatory functions of H. erinaceum, we prepared water extract from H. erinaceum (WEHE) and investigated its ability to activate macrophages and to induce nitric oxide (NO) production in macrophages. Rat peritoneal macrophages stimulated with 1 to 100 mug/ml of WEHE for 24, 48, or 72 h produced NO in a time- and dose-dependent manner. Reverse transcription-polymerase chain reaction demonstrated that WEHE augmented the steady-state level of inducible NO synthase (iNOS) mRNA in both the peritoneal macrophages and a murine macrophage cell-line, RAW 264.7. Electrophoretic mobility shift assay showed that WEHE increased DNA binding activity of the transcription factor NF-kappaB, which is responsible for iNOS gene expression. Furthermore, its trans-acting activity was confirmative as determined by in vitro transfection assay using a reporter gene construct, p(NF-kappaB)(3)-CAT, whose expression is solely regulated by the activity of NF-kappaB. Concomitantly with the activation of NF-kappaB, WEHE markedly decreased intracellular IkappaBalpha level as demonstrated by Western blot assay. These results suggested that WEHE induces iNOS gene expression followed by NO production in macrophages via enhancing the activation of transcription factor, NF-kappaB.

Structural elucidation of a novel fucogalactan that contains 3-O-methyl rhamnose isolated from the fruiting bodies of the fungus, Hericium erinaceus

A new heteropolysaccharide, HEPF3, was isolated from the fruiting bodies of Hericium erinaceus. HEPF3 has a molecular weight of 1.9 x 10(4) Da and is composed of fucose and galactose in a ratio of 1:4.12. Compositional analysis, methylation analysis, together with 1H and 13C NMR spectroscopy established that HEPF3 consists of a branched pentasaccharide repeating unit with the following structure: [structure: see text]. HEPF3 also contains a minor proportion of 3-O-methylrhamnose that is thought to terminate the polymer main chain.

Cell to Cell Contact Through ICAM-1-LFA-1 and TNF-α Synergistically Contributes to GM-CSF and Subsequent Cytokine Synthesis in DBA/2 Mice Induced by 1,3-β-D-Glucan SCG

SCG is a major 6-branched 1,3-beta-D-glucan in Sparassis crispa Fr. showing antitumor activity. We recently found that the splenocytes from naive DBA/1 and DBA/2 mice are potently induced by SCG to produce interferon- gamma (IFN-gamma), tumor necrosis factor-alpha (TNF-alpha), granulocyte-macrophage colony-stimulating factor (GM-CSF), and interleukin-12p70 (IL-12p70), and that GM-CSF plays a key biologic role among these cytokines. In this study, we investigated the contribution of cell-cell contact and soluble factors to cytokine induction by SCG in DBA/2 mice. Cell-cell contact involving intercellular adhesion molecule-1 (ICAM-1) and lymphocyte function-associated antigen-1 (LFA-1) was an essential step for the induction of GM-CSF and IFN-gamma by SCG but not for the induction of TNF-alpha or IL-12p70 by SCG. SCG directly induced adherent splenocytes to produce TNF-alpha and IL-12p70. GM-CSF was required for the induction of TNF-alpha by SCG, and in turn, TNF-alpha enhanced the release of GM-CSF and thereby augmented the induction of IL-12p70 and IFN-gamma by SCG. Neutralization of IL-12 significantly inhibited the induction of IFN-gamma by SCG. We concluded that induction of GM-CSF production by SCG was mediated through ICAM-1 and LFA-1 interaction, GM-CSF subsequently contributed to further cytokine induction by SCG, and reciprocal actions of the cytokines were essential for enhancement of the overall response to SCG in DBA/2 mice.

Effect of Candida albicans cell wall glucan as adjuvant for induction of autoimmune arthritis in mice

Collagen-induced arthritis (CIA) is an experimental model of rheumatoid arthritis (RA) and has aided research into the pathogenesis of inflammatory joint disease. Typically, Type II collagen (CII) emulsified with Freund's complete adjuvant (FCA) is injected into DBA/1 mice. After a booster injection, the mice develop inflammation of the paws. But the fact that the immunization of CII alone does not induce arthritis suggests that activation of the immune system by an adjuvant is necessary for induction of the arthritis. In the present study, we investigated the ability of beta-glucans derived from Candida albicans to act as an adjuvant to induce autoimmune arthritis. DBA/1 mice were injected with CII emulsified with FCA or particulate beta-glucan, OX-CA, on day 0 and given a booster at day 21. Mice immunized with CII plus OX-CA developed arthritis at around 7-10 days after the booster injection. Similarly, mice administered CII emulsified with FCA developed arthritis with the same time course. The mice immunized with CII and OX-CA had a more severe arthritis than those immunized with CII and FCA. Histological changes and production of anti-CII antibody were observed regardless of the type of injection. In addition, components of C. albicans were also tested for their ability to induce arthritis as an adjuvant. The results showed that CSBG, which is a soluble beta-glucan, acted as an adjuvant for CIA but CAWS, which is a mannoprotein-beta-glucan complex, did not. In conclusion, beta-glucan derived from C. albicans acted as an adjuvant and the injection with CII resulted in arthritis with the production of anti-CII autoantibody. The results strongly suggested that fungal metabolites such as beta-glucans have the capacity to induce and exacerbate autoimmune diseases such as RA.

Elevated serum beta-D-glucan level and depressed neutrophil phagocytosis in a heatstroke patient

Endotoxemia has been reported as a mechanism for the fatal sequela after heatstroke. Subsequent disseminated fungal infection in a heatstroke patient has been also described. Beta-D-glucan, a constituent of the fungal cell wall, is an early diagnostic measure for fungal infection. In a heatstroke case, we examined for the first time levels of serum beta-d-glucan and endotoxin. A 34-year-old man with a body temperature of 43.5 degrees C was admitted in a state of shock. Prior to the development of disseminated intravascular coagulopathy (DIC), a remarkable elevation of serum beta-D-glucan level to 116 pg/mL (normal level<6.0 pg/mL) was revealed on the first day of admission. However, serum endotoxin was not detected when using a method that excluded beta-D-glucan contamination from endotoxin measurement (normal level<1.0 pg/mL). This change of beta-D-glucan level was accompanied by a depressed neutrophil function, especially in phagocytosis of 34% (normal range 70-90%) but not in bacterocidal function (81% versus a normal range of 70-100%). After intensive care including continuous hemodiafiltration, the patient regained consciousness but remained ataxic due to cerebellar infarction, which might have resulted from DIC, and subsequent bilateral fungal oculitis were revealed 45 days after admission. This case report demonstrates the elevation of serum beta-D-glucan but normal endotoxin levels after heatstroke, which may prompt further study to re-examine the serum levels of endotoxin in such catastrophic insults.

Protective effect of β-glucan on lung injury after cecal ligation and puncture in rats

OBJECTIVE

Understanding the biological mediators involved in the complex inflammatory response of sepsis and acute lung injury offers the possibility of future investigations targeting treatment based on these mediators. This study investigated whether macrophage activator beta-glucan has a protective effect on acute lung injury in an experimental model of sepsis.

DESIGN AND SETTING

Experimental study in an experimental research center.

MATERIALS

30 rats randomized into three groups (sham, sepsis, and beta-glucan).

INTERVENTIONS

Cecal ligation and puncture were performed in the beta-glucan and sepsis groups. The beta-glucan group was given a single intraperitoneal dose of beta-glucan (4 mg/kg) following cecal ligation.

MEASUREMENTS AND RESULTS

Rats treated with beta-glucan had fewer circulating neutrophils, more blood monocytes, and higher serum interleukin 6 levels than septic animals. The percentages of neutrophils and lymphocytes from the bronchoalveolar lavage fluid and the myeloperoxidase activity measured in the lung tissue were lower in the beta-glucan group than in the sepsis group. Less alveolar hemorrhage and neutrophil infiltration were observed in lungs from animals in the beta-glucan group in the septic groups.

CONCLUSIONS

In this rat model of intra-abdominal sepsis beta-glucan treatment partially protected against secondary lung injury, decreased lung hemorrhages, and lung neutrophilia. These results suggest that beta-glucan protects against sepsis-associated lung damage.

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.

Structural investigation of a novel rhamnoglucogalactan isolated from the fruiting bodies of the fungus Hericium erinaceus

A new heteropolysaccharide (HEP-1) was isolated from the fruiting bodies of Hericium erinaceus. It was estimated to have a molecular weight of 1.8x10(4) da and showed [alpha](D)(20) +129 (c 0.295, H(2)O). HEP-1 is composed of rhamnose, galactose, and glucose in the ratio of 1.19:3.81:1.00. Its structural features were investigated using composition analysis, methylation analysis, partial hydrolysis, and IR and NMR spectroscopy. The results showed that HEP-1 has a (1-->6)-linked alpha-d-galactopyranosyl backbone with branches that are composed of rhamnose and glucose attached to O-2.

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.

Surface glycans of Candida albicans and other pathogenic fungi: physiological roles, clinical uses, and experimental challenges

Although fungi have always been with us as commensals and pathogens, fungal infections have been increasing in frequency over the past few decades. There is a growing body of literature describing the involvement of carbohydrate groups in various aspects of fungal disease. Carbohydrates comprising the cell wall or capsule, or as a component of glycoproteins, are the fungal cell surface entities most likely to be exposed to the surrounding environment. Thus, the fungus-host interaction is likely to involve carbohydrates before DNA, RNA, or even protein. The interaction between fungal and host cells is also complex, and early studies using whole cells or crude cell fractions often produced seemingly conflicting results. What was needed, and what has been developing, is the ability to identify specific glycan structures and determine how they interact with immune system components. Carbohydrate analysis is complicated by the complexity of glycan structures and by the challenges of separating and detecting carbohydrates experimentally. Advances in carbohydrate chemistry have enabled us to move from the foundation of composition analysis to more rapid characterization of specific structures. This, in turn, will lead to a greater understanding of how fungi coexist with their hosts as commensals or exist in conflict as pathogens.

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.