Anti-infective effect of poly-beta 1-6-glucotriosyl-beta 1-3-glucopyranose glucan in vivo

Sustainable production and pharmaceutical applications of β-glucan from microbial sources

β-glucans are a large class of complex polysaccharides found in abundant sources. Our dietary sources of β-glucans are cereals that include oats and barley, and non-cereal sources can consist of mushrooms, microalgae, bacteria, and seaweeds. There is substantial clinical interest in β-glucans; as they can be used for a variety of diseases including cancer and cardiovascular conditions. Suitable sources of β-glucans for biopharmaceutical applications include bacteria, microalgae, mycelium, and yeast. Environmental factors including culture medium can influence the biomass and ultimately β-glucan content. Therefore, cultivation conditions for the above organisms can be controlled for sustainable enhanced production of β-glucans. This review discusses the various sources of β-glucans and their cultivation conditions that may be optimised to exploit sustainable production. Finally, this article discusses the immune-modulatory potential of β-glucans from these sources.

Clinically proven natural products, vitamins and mineral in boosting up immunity: A comprehensive review

BACKGROUND

and Purposes: The terminology "immune boost-up" was the talk of the topic in this Covid-19 pandemic. A significant number of the people took initiative to increase the body's defense capacity through boosting up immunity worldwide. Considering this, the study was designed to explain the natural products, vitamins and mineral that were proved by clinical trail as immunity enhancer.

METHODS

Information was retrieved from SciVerse Scopus ® (Elsevier Properties S. A, USA), Web of Science® (Thomson Reuters, USA), and PubMed based on immunity, nutrients, natural products in boosting up immunity, minerals and vitamins in boosting up immunity, and immune booster agents.

RESULT

A well-defined immune cells response provide a-well functioning defense system for the human physiological system. Cells of the immune system must require adequate stimulation so that these cells can prepare themselves competent enough to fight against any unintended onslaught. Several pharmacologically active medicinal plants and plants derived probiotics or micronutrients have played a pivotal role in enhancing the immune boost-up process. Their role has been well established from the previous study. Immune stimulating cells, especially cells of acquired immunity are closely associated with the immune-boosting up process because all the immunological reactions and mechanisms are mediated through these cells.

CONCLUSION

This article highlighted the mechanism of action of different natural products, vitamins and mineral in boosting up the immunity of the human body and strengthening the body's defense system. Therefore, it is recommended that until the specific immune-boosting drugs are available in pharma markets, anyone can consider the mentioned products as dietary supplements to boost up the immunity.

β-Glucan Metabolic and Immunomodulatory Properties and Potential for Clinical Application

β-glucans are complex polysaccharides that are found in several plants and foods, including mushrooms. β-glucans display an array of potentially therapeutic properties. β-glucans have metabolic and gastro-intestinal effects, modulating the gut microbiome, altering lipid and glucose metabolism, reducing cholesterol, leading to their investigation as potential therapies for metabolic syndrome, obesity and diet regulation, gastrointestinal conditions such as irritable bowel, and to reduce cardiovascular and diabetes risk. β-glucans also have immune-modulating effects, leading to their investigation as adjuvant agents for cancers (solid and haematological malignancies), for immune-mediated conditions (e.g., allergic rhinitis, respiratory infections), and to enhance wound healing. The therapeutic potential of β-glucans is evidenced by the fact that two glucan isolates were licensed as drugs in Japan as immune-adjuvant therapy for cancer in 1980. Significant challenges exist to further clinical testing and translation of β-glucans. The diverse range of conditions for which β-glucans are in clinical testing underlines the incomplete understanding of the diverse mechanisms of action of β-glucans, a key knowledge gap. Furthermore, important differences appear to exist in the effects of apparently similar β-glucan preparations, which may be due to differences in sources and extraction procedures, another poorly understood issue. This review will describe the biology, potential mechanisms of action and key therapeutic targets being investigated in clinical trials of β-glucans and identify and discuss the key challenges to successful translation of this intriguing potential therapeutic.

Role of nutraceuticals during the transition period of dairy cows: a review

The transition period of dairy cattle is characterized by a number of metabolic, endocrine, physiologic, and immune adaptations, including the occurrence of negative energy balance, hypocalcemia, liver dysfunction, overt systemic inflammatory response, and oxidative stress status. The degree and length of time during which these systems remain out of balance could render cows more susceptible to disease, poor reproductive outcomes, and less efficient for milk production and quality. Studies on both monogastrics and ruminants have reported the health benefits of nutraceuticals (e.g. probiotics, prebiotics, dietary lipids, functional peptides, phytoextracts) beyond nutritional value, interacting at different levels of the animal’s physiology. From a physiological standpoint, it seems unrealistic to disregard any systemic inflammatory processes. However, an alternate approach is to modulate the inflammatory process per se and to resolve the systemic response as quickly as possible.

To this aim, a growing body of literature underscores the efficacy of nutraceuticals (active compounds) during the critical phase of the transition period. Supplementation of essential fatty acids throughout a 2-month period (i.e. a month before and a month after calving) successfully attenuates the inflammatory status with a quicker resolution of phenomenon. In this context, the inflammatory and immune response scenario has been recognized to be targeted by the beneficial effect of methyl donors, such as methionine and choline, directly and indirectly modulating such response with the increase of antioxidants GSH and taurine. Indirectly by the establishment of a healthy gastrointestinal tract, yeast and yeast-based products showed to modulate the immune response, mitigating negative effects associated with parturition stress and consequent disorders.

The use of phytoproducts has garnered high interest because of their wide range of actions on multiple tissue targets encompassing a series of antimicrobial, antiviral, antioxidant, immune-stimulating, rumen fermentation, and microbial modulation effects. In this review, we provide perspectives on investigations of regulating the immune responses and metabolism using several nutraceuticals in the periparturient cow.

Effects of β-Glucan on the Release of Nitric Oxide by Macrophages Stimulated with Lipopolysaccharide

This research analyzed the effect of β-glucan that is expected to alleviate the production of the inflammatory mediator in macrophagocytes, which are processed by the lipopolysaccharide (LPS) of Escherichia. The incubated layer was used for a nitric oxide (NO) analysis. The DNA-binding activation of the small unit of nuclear factor-κB was measured using the enzyme-linked immunosorbent assay-based kit. In the RAW264.7 cells that were vitalized by Escherichia coli (E. coli) LPS, the β-glucan inhibited both the combatant and rendering phases of the inducible NO synthase (iNOS)-derived NO. β-Glucan increased the expression of the heme oxygenase-1 (HO-1) in the cells that were stimulated by E. coli LPS, and the HO-1 activation was inhibited by the tin protoporphyrin IX (SnPP). This shows that the NO production induced by LPS is related to the inhibition effect of β-glucan. The phosphorylation of c-Jun N-terminal kinases (JNK) and the p38 induced by the LPS were not influenced by the β-glucan, and the inhibitory κB-α (IκB-α) decomposition was not influenced either. Instead, β-glucan remarkably inhibited the phosphorylation of the signal transducer and activator of transcription-1 (STAT1) that was induced by the E. coli LPS. Overall, the β-glucan inhibited the production of NO in macrophagocytes that was vitalized by the E .coli LPS through the HO-1 induction and the STAT1 pathways inhibition in this research. As the host immune response control by β-glucan weakens the progress of the inflammatory disease, β-glucan can be used as an effective immunomodulator.

Orally delivered β-glucans aggravate dextran sulfate sodium (DSS)-induced intestinal inflammation

β-Glucans have beneficial health effects due to their immune modulatory properties. Oral administration of β-glucans affects tumour growth, microbial infection, sepsis, and wound healing. We hypothesized that pre-treatment with orally delivered soluble and particulate β-glucans could ameliorate the development of aggravate dextran sulfate sodium (DSS) induced intestinal inflammation. To study this, mice were orally pre-treated with β-glucans for 14 days. We tested curdlan (a particulate β-(1,3)-glucan), glucan phosphate (a soluble β-(1,3)-glucan), and zymosan (a particle made from Saccharomyces cerevisiae, which contains around 55% β-glucans). Weight loss, colon weight, and feces score did not differ between β-glucan and vehicle treated groups. However, histology scores indicated that β-glucan-treated mice had increased inflammation at a microscopic level suggesting that β-glucan treatment worsened intestinal inflammation. Furthermore, curdlan and zymosan treatment led to increased colonic levels of inflammatory cytokines and chemokines, compared to vehicle. Glucan phosphate treatment did not significantly affect cytokine and chemokine levels. These data suggest that particulate and soluble β-glucans differentially affect the intestinal immune responses. However, no significant differences in other clinical colitis scores between soluble and particulate β-glucans were found in this study. In summary, β-glucans aggravate the course of dextran sulfate sodium (DSS)-induced intestinal inflammation at the level of the mucosa.

Immunomodulation of Fungal β-Glucan in Host Defense Signaling by Dectin-1

During the course of evolution, animals encountered the harmful effects of fungi, which are strong pathogens. Therefore, they have developed powerful mechanisms to protect themselves against these fungal invaders. β-Glucans are glucose polymers of a linear β(1,3)-glucan backbone with β(1,6)-linked side chains. The immunostimulatory and antitumor activities of β-glucans have been reported; however, their mechanisms have only begun to be elucidated. Fungal and particulate β-glucans, despite their large size, can be taken up by the M cells of Peyer's patches, and interact with macrophages or dendritic cells (DCs) and activate systemic immune responses to overcome the fungal infection. The sampled β-glucans function as pathogen-associated molecular patterns (PAMPs) and are recognized by pattern recognition receptors (PRRs) on innate immune cells. Dectin-1 receptor systems have been incorporated as the PRRs of β-glucans in the innate immune cells of higher animal systems, which function on the front line against fungal infection, and have been exploited in cancer treatments to enhance systemic immune function. Dectin-1 on macrophages and DCs performs dual functions: internalization of β-glucan-containing particles and transmittance of its signals into the nucleus. This review will depict in detail how the physicochemical nature of β-glucan contributes to its immunostimulating effect in hosts and the potential uses of β-glucan by elucidating the dectin-1 signal transduction pathway. The elucidation of β-glucan and its signaling pathway will undoubtedly open a new research area on its potential therapeutic applications, including as immunostimulants for antifungal and anti-cancer regimens.

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.

[Effect of oral administration of β-D-glucan from Aureobasidium pullulans ADK-34 on Candida and MRSA infections in immunosuppressed mice]

We examined the effect of the oral administration of β-D-glucan derived from Aureobasidium pullulans ADK-34 (AP-FBG) on Candida albicans or methicillin-resistant Staphylococcus aureus (MRSA) infection in immunosuppressed mice. Mice pretreated with cyclophosphamide (CY) were intraperitoneally administered AP-FBG for 4 days and then infected with 6×10(4) C. albicans cells. In a preliminary experiment, the survival time of the Candida-infected mice treated with AP-FBG was clearly prolonged. Similarly, the effect of the oral administration of AP-FBG was examined. Mice were orally given 2.5% AP-FBG in feed for 42 days from 14 days prior to 2×10(4) C. albicans cells infection. The survival time of mice treated with AP-FBG was significantly prolonged and the viable cell count in the kidneys of the survivors was significantly decreased at 30 days after infection. The effects of the oral administration of AP-FBG on intestinal MRSA infection were also examined. Mice were given 2.5% AP-FBG orally in feed for 30 days before and after oral MRSA infection and treated with CY 12 days after the infection. The number of viable MRSA cells or the IgA production in feces did not significantly change, while AP-FBG administration seemed to relieve temporally the loss of body weight of mice.

CONCLUSIONS

These results suggest that oral pre-administration of AP-FBG promoted resistance of CY-treated mice to C. albicans and lessened the weight reduction of CY-mice infected by MRSA.

Preparation, characterization, and biological properties of β-glucans

β-Glucans are soluble fibers with physiological functions, such as, interference with absorption of sugars and reduction of serum lipid levels. β-glucans are found in different species, such as, Rhynchelytrum repens, Lentinus edodes, Grifola frondosa, Tremella mesenterica, Tremella aurantia, Zea may, Agaricus blazei, Phellinus baummi, Saccharomyces cerevisae (yeast), and Agaricus blazei murell (mushroom). Analysis of the fractions reveals the presence of arabinose, glucose, xylose, and traces of rhamnose and galactose. The presence of β-glucan in these fractions is confirmed by hydrolyzing the polymers with endo-β-glucanase from Bacillus subtilis, followed by high-performance liquid chromatography (HPLC) analysis of the characteristic oligosaccharides produced. The 4 M KOH fractions from different tissues are 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 is similar (250 kDa) to that of the maize coleoptiles β-glucan used for comparison. The 4 M KOH fraction injected into rats with streptozotocin-induced diabetes has shown hypoglycemic activity, reducing blood sugar to normal levels for approximately 24 hours. This performance is better than that obtained with pure β-glucan from barley, which decreases blood sugar levels for about four hours. These results suggest that the activity of β-glucans is responsible for the use of this plant extract as a hypoglycemic drug in folk medicine.

β-Glucan treatment prevents progressive burn ischaemia in the zone of stasis and improves burn healing: an experimental study in rats

Saving the zone of stasis is one of the major goals of burn specialists. Increasing the tissue tolerance to ischaemia and inhibiting inflammation have been proposed to enable salvage of this zone. After a burn, excessive inflammation, including increased vascular permeability, local tissue oedema and neutrophil activation, causes local tissue damage by triggering vascular thrombosis and blocking capillaries, resulting in tissue ischaemia and necrosis. Oxygen radicals also contribute to tissue damage after a burn. However, macrophages play a pivotal role in the response to burn. We studied β-glucan because of its many positive systemic effects that are beneficial to burn healing, including immunomodulatory effects, antioxidant effects (free-radical scavenging activity) and effects associated with the reduction of the inflammatory response. There were four test groups in this study with eight rats in each group. Group 1 was the control group, group 2 was administered a local pomade (bacitracin+neomycin sulphate), group 3 received β-glucan (50 mg kg(-1), orally) + the local pomade and group 4 received β-glucan. Burns were created using a brass comb model. Macroscopic, histopathological and statistical assessments were performed. Samples were harvested on the 3rd, 7th and 21 days for analysis. The neutrophilic infiltration into the zone of stasis was analysed on day 3. Macrophage infiltration, fibroblast proliferation, angiogenesis and re-epithelialisation ratios in the zone of stasis were analysed on days 7 and 21. The β-glucan groups (groups 3 and 4) exhibited lower neutrophil counts on the 3rd day, and macrophage infiltration, fibroblast proliferation, angiogenesis and re-epithelialisation were very high in these groups on the 7th day. In particular, re-epithelialisation on the 21st day was significantly better in the β-glucan groups. This study demonstrated that β-glucan may prevent neutrophil-dependent tissue damage and burn-induced oxidative injury through its anti-inflammatory and antioxidant properties. We speculate that the inhibition of neutrophil activation preserves vascular patency by preventing capillary blockage. β-Glucan is also a powerful macrophage stimulator, and is therefore very effective in saving the zone of stasis.

Improved antimicrobial host defense in mice following poly-(1,6)-β-D-glucopyranosyl-(1,3)-β-D-glucopyranose glucan treatment by a gender-dependent immune mechanism

Clinical trials with biological modifiers targeting specific inflammatory mediators associated with severe sepsis have shown no or limited survival benefit. The approach taken in studies reported here was to limit the point source of intra-abdominal infection by potentiating innate immune function, thereby lessening the severity of sepsis and improving survival. Soluble beta-glucans, glucose polymers of the fungal cell wall, have been shown to stimulate innate immune host defense in animal and human studies when administered prior to an infectious challenge. We evaluated the effects of poly-(1,6)-β-d-glucopyranosyl-(1,3)-β-d-glucopyranose glucan (PGG glucan) on overall survival when administered intraperitoneally after the onset of polymicrobial infection by cecal ligation and puncture (CLP). Since gender-dependent differences in host immune response to infection have been reported, male and female mice were prospectively stratified for PGG glucan treatment. Outbred CD-1 mice were administered 10 mg/kg of body weight PGG glucan or the polysaccharide control, dextran, 1 h after CLP. Six hours after CLP, blood samples were obtained for cytokine measurements. Surprisingly, a gender-dependent effect on the response to PGG glucan was revealed. PGG glucan enhanced survival in female mice over a 10-day period, but survival in males was improved for only 24 h. In female mice, PGG glucan reduced interleukin-6 (IL-6) and IL-10 levels and reduced the bacterial burden in the liver. Ovariectomy abrogated the response to PGG glucan. Together, the translational potential of these findings is the indicated use of PGG glucan given locally, rather than intravenously, for improved source control during the management of sepsis. This therapy does not require prophylactic beta-glucan administration.

Protective effects of fungal β-(1→3)-D-glucan against oxidative stress cytotoxicity induced by depleted uranium in isolated rat hepatocytes

Previous reports suggested that certain carbohydrate polymers, such as β-(1→3)-D-glucan, may possess free radical scavenging activity. The present study examined the free radical scavenging activity of a carbohydrate polymer, β-(1→3)-D-glucan against oxidative stress induced by depleted uranium in isolated rat hepatocytes. Addition of U (VI) (uranyl acetate) to isolated rat hepatocytes results in reactive oxygen species (ROS) formation, rapid glutathione depletion, mitochondrial membrane potential collapse and lysosomal membrane rupture before hepatocyte lysis occurred. Our results showed that quite similar to silymarin, which is a known antioxidant and radical scavenger, tiny concentration of β-glucan (138 nM) very successfully protected the hepatocytes against cell lysis and all oxidative stress cytotoxicity endpoints caused by depleted uranium including ROS formation, glutathione depletion, decreased mitochondrial membrane potential, lysosomal membrane rupture and caspase 3 activity increase. In conclusion, our results confirmed the antioxidant and radical scavenging activity of β-(1→3)-D-glucan and suggested this compound and silymarin as possible drug candidates for prophylaxis and treatment against depleted uranium toxic effects.

Oral administration of beta-1,3/1,6-glucan to dogs temporally changes total and antigen-specific IgA and IgM

The effect of oral administration of beta-1,3/1,6-glucans from Saccharomyces cerevisiae on humoral immunity in domestic dogs is not known. In this study, 15 beagle dogs were orally given MacroGard tablets, which contain 150 mg of this beta-glucan, daily for 4 weeks. At the end of this period, the total serum immunoglobulin A (IgA) level decreased significantly in the group treated with the glucan compared to that in the control group as well as compared to the concentrations before supplementation. In contrast, the total serum IgM level rose significantly, whereas no effect on the IgG level occurred. Similar changes were seen in Bordetella-specific IgA and IgM titers following vaccination during the supplementation period. The IgA concentration also became significantly lower in the saliva and tears of the glucan group than in the placebo group. The effects disappeared 1 week after the cessation of the supplementation. In conclusion, the results showed a temporary change in the isotype profile during glucan supplementation.

Hepatoprotective effects of paramylon, a beta-1, 3-D-glucan isolated from Euglena gracilis Z, on acute liver injury induced by carbon tetrachloride in rats

Paramylon is a beta-(1-3)-D-glucan isolated from Euglena gracilis Z. This study was designed to evaluate the protective effects of paramylon on liver injury induced by carbon tetrachloride (CCl(4)) in rats. Wistar stain male rats were orally administered paramylon (500, 1,000 and 2,000 mg/kg body weight) before treatment with a single intraperitoneal dose of 50% CCl(4) (2 ml/kg body weight). The rats were sacrificed 24 hr later, and blood samples were collected for assay of serum biochemical parameters. The livers were excised to evaluate the activity of antioxidant enzymes. Histopathological examination of the livers was also performed. The results showed that the treatment of paramylon prevented elevation of the serum levels of hepatic enzyme markers and inhibited fatty degeneration and hepatic necrosis induced by CCl(4). Pre-administration of paramylon reduced the liver apoptotic index. The treatment of paramylon recovered reductions of activity of hepatic superoxide dismutase, catalase and glutathione peroxidase induced by CCl(4). These results demonstrate that paramylon exhibits protective action on acute hepatic injury induced by CCl(4) via an antioxidative mechanism. To the best of our knowledge, this is the first report of a hepatoprotective effect based on the antioxidative action of paramylon.

Protective effects of N-acetylcysteine and beta-glucan pretreatment on oxidative stress in cecal ligation and puncture model of sepsis

This study was designed to compare the effect of pretreatment with N-acetylcysteine (NAC) and beta -glucan (beta GLU) on inflammatory response in a rat model of sepsis. The study was performed in the animal laboratory of the Kahramanmaras Sutcu Imam University, School of Medicine. Forty rats were randomized into four groups (control, sham, NAC, and beta GLU). Control and Sham groups received saline or NAC (200 mg/kg, po) in the NAC group and beta GLU (50 mg/kg, po) in the betaGLU group via intragastric gavage once a day for 10 days and 30 min prior to surgery. Sepsis was induced by cecal ligation and puncture (CLP) in rats. In the NAC, beta GLU, and control groups, a laparotomy was performed with the CLP procedure. In the sham group, laparotomy was performed and cecum was manipulated but not ligated or perforated. TNF-alpha and IL-6 levels were significantly elevated in the control group and decreased in the NAC and beta GLU groups. IL-10 levels were significantly increased in the beta GLU group (p < .05). Superoxide dismutase and catalase levels in the liver tissue were significantly increased in the NAC and beta GLU groups, whereas superoxide dismutase levels were higher in the beta GLU pretreatment group than the NAC pretreatment group (p < 0.05). Malondialdehyde levels in the liver tissue were significantly elevated in the control group and decreased in the NAC and beta GLU groups (p < .05). Prophylactic administration of NAC or beta GLU similarly ameliorated sepsis syndrome by reduction of the proinflammatory cytokines and increase of the anti-inflammatory cytokine levels and accession of cellular antioxidants, which protect cells from oxidative stress, thereby recruiting inflammatory cells into tissue.

Toxicological assessment of a particulate yeast (1,3/1,6)-β-d-glucan in rats

This study investigates the toxicity of WGP 3-6, a yeast-derived beta-glucan ingredient, during single-dose acute and sub-chronic toxicity studies in rats. For the acute study, Fisher-344 rats were administered WGP 3-6 via gavage at a dose of 2000 mg/kg body weight, and any evidence of toxicity was monitored over a 14-day period. WGP 3-6 was well tolerated, indicating that the LD(50) value is greater than 2000 mg/kg body weight. For the sub-chronic study, Fisher-344 rats (10/sex/group) were randomly allocated to receive daily gavage treatment with WGP 3-6 at doses of 0, 2, 33.3, or 100 mg/kg body weight. Control and high-dose satellite recovery groups of each sex also were included. Full toxicological monitoring and endpoint investigations were performed throughout and upon completion of the study. No negative effects on animal weights or food consumption attributable to WGP 3-6 were evident at any dose. In addition, no mortality, clinical pathology, functional/behavioral, microscopic, or gross observations indicating toxicity were observed. Sporadic changes in some biochemical and hematological parameters were observed; however, since the effects were within the physiological ranges in historical controls, were not dose-responsive, or were not observed in both sexes, they were determined to be of no toxicological significance. In conclusion, no adverse or toxic effects were observed after subchronic oral administration of 2, 33.3, or 100mg/kg body weight/day of WGP 3-6 in Fisher-344 rats, and therefore, a no observed adverse effect level (NOAEL) of 100 mg/kg body weight/day, the highest dose tested, was determined.

Oral and systemic administration of beta-glucan protects against lipopolysaccharide-induced shock and organ injury in rats

beta-Glucans are glucose polymers with a variety of stimulatory effects on the immune system. The objective of this study was to determine the effect of prophylactic oral administration of soluble Saccharomyces cerevisiae-derived beta-1,3/1,6-glucan (SBG) on the outcome of experimental endotoxaemia and shock-associated organ injury. Male Wistar rats were pretreated with SBG orally (SBGpo, 20 mg/kg/day) for 14 days, subcutaneously (SBGsc, 2 mg/kg/day) for 3 days, or vehicle (placebo). Rats were anaesthetized and subjected to endotoxaemia by intravenous infusion of Escherichia coli lipopolysaccharide (LPS) (6 mg/kg) or saline infusion (sham). We observed significant levels of plasma beta-glucan in the SBGpo group (P<0 x 5), although the SBGsc group had levels approximately 40-fold higher despite a 10-fold lower dose. SBG prophylaxis caused enhanced blood pressure recovery following LPS-induced blood pressure collapse. Oral treatment with SBG attenuated the LPS-induced rise in plasma creatinine levels (P<0 x 05), indicating protection against renal injury. SBG also attenuated the plasma levels of aspartate aminotransferase and alanine aminotransferase (SBGpo, P<0 x 01; SBGsc, P<0 x 01), indicating protection against LPS-induced hepatic injury. A moderate increase in baseline interleukin (IL)-1beta levels was observed in the SBGsc group (P< 0 x 05). In the LPS-challenged rats, plasma levels of proinflammatory cytokines was moderately reduced in both SBG-treated groups compared to placebo. SBG treatment, particularly oral administration, had a striking effect on the haemodynamics of LPS-treated rats, although only a minute fraction of the orally administered beta-glucan translocated to the circulation. Enhanced organ perfusion may thus be responsible for the attenuated levels of indicators of kidney and liver injury seen in SBG-treated rats.

β-Glucan protects against chronic nicotine-induced oxidative damage in rat kidney and bladder

In this study, we investigated the protective effect of β-glucan against nicotine induced oxidative damage in urinary bladder and kidney tissues. Wistar albino rats were injected i.p. with nicotine hydrogen bitartarate (0.6mg/kg daily for 21 days) or saline. β-Glucan (50mg/kg, p.o.) was administered alone or with nicotine injections for 21 days. After decapitation, the urinary bladder and kidney tissues were taken for the measurement of malondialdehyde (MDA) and glutathione (GSH) levels, and myeloperoxidase (MPO) activity. Tissue samples were also examined histologically. In serum samples MDA, GSH, BUN, creatinine, TNF-α levels and LDH activity were analyzed. Chronic nicotine administration caused a significant decrease in GSH levels and increases in MDA levels and MPO activity in kidney and bladder tissues, suggesting oxidative organ damage, which was also histologically verified. Furthermore, β-glucan restored the reduced GSH levels, while it significantly decreased MDA levels and MPO activity. Renal function tests, LDH and TNF-α levels, which were increased significantly due to nicotine administration, were decreased with β-glucan treatment. The present data suggest that β-glucan supplementation effectively counteracts the chronic nicotine toxicity and attenuates oxidative damage of bladder and kidney tissues possibly by its antioxidant effects.

Supplemental vitamin C and yeast cell wall β-glucan as growth enhancers in newborn pigs and as immunomodulators after an endotoxin challenge after weaning1

To test possible dietary immune modulators, 32 crossbred male pigs were given 1 of 4 dietary treatments (8 pigs/treatment): control, Saccharomyces cerevisiae with beta-glucan (Energy Plus, Natural Chem Industries LTD, Houston, TX; 0.312 g/kg of BW, 2.5% of diet), vitamin C (Stay C 35, DSM Nutritional Products Inc., Prisippany, NJ; 75 ppm), or beta-glucan plus vitamin C together (combination; 0.312 g/kg of BW and 75 ppm, respectively). Supplements were given in whole milk within 36 h of birth and then daily for 2 wk until weaning, when the supplement was given in feed for an additional 2 wk. Growth was recorded during the 4 wk of supplement delivery. An i.v. lipopolysaccharide challenge (LPS; 150 microg/kg) was given 14 d postweaning at 0900. Behavior was observed, and blood samples were collected every 30 min for 4 h via a jugular catheter from -1 (0800) to 3 (1200) h relative to challenge (-60, -30, 0, 30, 60, 90, 120, 150, and 180 min), and tissues were collected after exsanguination. Beta-glucan (glucan and combination) increased (P < 0.05) BW and ADG compared with vitamin C and control. Cortisol concentrations showed an interaction (P < 0.05) of the beta-glucan and vitamin C. Intestinal expression of tumor-necrosis factor (TNF)-alpha mRNA was greatest for vitamin C and beta-glucan compared with control and combination, and liver TNF-alpha mRNA expression showed a main effect (P < 0.01) of beta-glucan. Lung expression of TNF-alpha mRNA exhibited a vitamin C effect (P < 0.01). In contrast, spleen had greater (P < 0.01) relative abundance of TNF-alpha mRNA in beta-glucan pigs. Intestinal expression of IL-1Ra mRNA was greater (P < 0.05) for vitamin C and beta-glucan treatments compared with the control and combination pigs. Liver expression of IL-1 receptor antagonist mRNA exhibited a vitamin C effect (P < 0.01). Lying and sleeping behaviors differed (P < 0.05) among treatments early in the observations (0700 to 0720), then sporadically until 50 min after the LPS injection. The vitamin C group slept less (P < 0.05) on those occasions. The time spent lying was least (P < 0.05) for the glucan and combination pigs immediately after the injection. These results show a complex interaction between vitamin C and this yeast product after LPS challenge, with differential expression in tissues by 2 h after LPS injections. The combination enhanced postweaning growth and reduced TNF-alpha expression of the intestinal and liver tissues, suggesting an important immunomodulatory role of the combination treatment.

Acetaminophen-induced toxicity is prevented by β-d-glucan treatment in mice

The protective effect of beta-glucan against oxidative injury caused by acetaminophen was studied in mice liver. BALB-c mice (25-30 g) were pre-treated with beta-d-glucan (50 mg/kg, p.o.) for 10 days and on the 11th day they received an overdose of acetaminophen (900 mg/kg, i.p.). Four hours after the acetaminophen injection, mice were decapitated and their blood was taken to determine serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), lactate dehydrogenase (LDH) and tumor necrosis factor-alpha (TNF-alpha) levels. Tissue samples of the liver were taken for histological examination or for the determination of levels of malondialdehyde, an end product of lipid peroxidation; glutathione (GSH), a key antioxidant; and myeloperoxidase activity, an index of tissue neutrophil infiltration. The formation of reactive oxygen species in hepatic tissue samples was monitored by using the chemiluminescence technique with luminol and lucigenin probes. Acetaminophen caused a significant decrease in the GSH level of the tissue, which was accompanied with significant increases in the hepatic luminol and lucigenin chemiluminescence values, malondialdehyde level, MPO activity and collagen content. Similarly, serum ALT, AST levels, as well as LDH and TNF-alpha, were elevated in the acetaminophen-treated group when compared with the control group. On the other hand, beta-d-glucan treatment reversed all these biochemical indices, as well as histopathological alterations that were induced by acetaminophen. In conclusion, these results suggest that beta-d-glucan exerts cytoprotective effects against oxidative injury through its antioxidant properties and may be of therapeutic use in preventing acetaminophen toxicity.

β-glucan ameliorates methotrexate-induced oxidative organ injury via its antioxidant and immunomodulatory effects

Methotrexate is an antifolate that is widely used in the treatment of rheumatic disorders and malignant tumors. The efficacy of methotrexate is often limited by severe side effects and toxic sequelae, where oxidative stress is noticeable. In the present study, the possible protective effect of beta-glucan in methotrexate-induced toxicity was investigated. Following a single dose of methotrexate injection (20 mg/kg), either saline or beta-glucan (50 mg/kg; orally) was administered for 5 days. After decapitation of the rats, trunk blood was obtained and the ileum, liver and kidney were removed to measure tissue malondialdehyde (MDA) and glutathione (GSH) levels, myeloperoxidase (MPO) activity and collagen content, as well as histological examination. Methotrexate caused a significant decrease in GSH levels, while MDA levels, MPO activity and collagen content were increased in all the tissues (P<0.05-0.001). On the other hand, administration of beta-glucan following methotrexate abolished the depletion of GSH and inhibited the increases in MDA, MPO activity and collagen content, while the histological analysis revealed that beta-glucan attenuated the tissue damage. Stimulation index, an indicator of oxidative burst in the neutrophils, was decreased by methotrexate (P<0.001), while beta-glucan abolished this effect. Furthermore, increased leukocyte apoptosis and cell death in methotrexate-treated animals were inhibited by beta-glucan (P<0.05). Thus, the findings of the present study suggest that beta-glucan, through its antioxidant and immunoregulatory effects, may be of therapeutic value in alleviating the leukocyte apoptosis, oxidative tissue injury and thereby the intestinal and hepatorenal side effects of methotrexate treatment.

Pressure ulcer-induced oxidative organ injury is ameliorated by β-glucan treatment in rats

Pressure ulcers (PU) cause morphological and functional alterations in the skin and visceral organs. In this study we investigated the role of oxidative damage in PUs and the probable beneficial effect of beta-glucan treatment against this damage. beta-glucan is known to have immunomodulatory effects. Experiments were carried on Wistar albino rats. PU was induced by applying magnets over steel plates that were implanted under the skin, to compress the skin and cause ischemia where removing the magnets cause reperfusion of the tissue. Within the first 12 h, rats were subjected to 5 cycles of ischemia/reperfusion (I/R), followed by 12 h ischemia. This protocol was repeated for 3 days. In treatment groups, twice a day during reperfusion periods, beta-glucan was either applied locally (25 mg/kg) as an ointment on skin, or administered orally (50 mg/kg) as a gavage. At the end of the experimental periods, tissue samples (skin, liver, kidney, lung, stomach, and ileum) were taken for the measurement of malondialdehyde (MDA)--an index of lipid peroxidation--and glutathione (GSH)--a key antioxidant--levels. Neutrophil infiltration was evaluated by the measurement of tissue myeloperoxidase activity, while collagen contents were measured for the evaluation of tissue fibrosis. Skin tissues were also examined microscopically. Liver and kidney functions were assayed in serum samples. Local treatment with beta-glucan inhibited the increase in MDA and MPO levels and the decrease in GSH in the skin induced by PU, but was less efficient in preventing the damage in visceral organs. However, systemic treatment prevented the damage in the visceral organs. Significant increases in creatinine, BUN, ALT, AST, LDH and collagen levels in PU group were prevented by beta-glucan treatment. The light microscopic examination exhibited significant degenerative changes in dermis and epidermis in the PU group. Tissue injury was decreased especially in the locally treated group. Thus, supplementing geriatric and neurologically impaired patients with adjuvant therapy of beta-glucan may have some benefits for successful therapy and improving quality of life.

Natural and modified (1-->3)-beta-D-glucans in health promotion and disease alleviation

A number of polysaccharides with beta-glycosidic linkage are widespread in nature in a variety of sources. All have a common structure and the (1-->3)-beta-D-glucan backbone is essential. They have attracted attention over the years because of their bioactive and medicinal properties. In many cases their functional role is a mystery, in others it is well established. Because of their insoluble chemical nature, particulate (1-->3)-beta-D-glucans are not suitable for many medical applications. Various methods of changing or modifying the beta-D-glucan chemical structure and transforming it to a soluble form have been published. The beta-D-glucan bioactive properties can be affected positively or negatively by such modifications. This review examines beta-glucan sources in nature, health effects and structure-activity relationships. It presents the current state of beta-D-glucan solubilization methods and discusses their effectiveness and application possibilities for the future.

β-glucan protects against burn-induced oxidative organ damage in rats

Thermal injury may lead to systemic inflammatory response, and multiple organ failure. Generation of reactive oxygen radicals and lipid peroxidation play important roles in burn-induced remote organ injury. In the present study, we investigated the putative protective effect of local or systemic beta-glucan treatment on burn-induced remote organ injury. Wistar albino rats were exposed to 90 degrees C bath for 10 s to induce thermal trauma. beta-glucan (3.75 mg/rat locally or 50 mg/kg orally) or saline was administered immediately after the trauma and were repeated twice daily in 48 h groups. Rats were decapitated either 6 or 48 h after burn injury and the skin, lung, liver, ileum and kidney tissues were taken for the measurement of malondialdehyde (MDA)--an index of lipid peroxidation--and glutathione (GSH)--a key antioxidant--levels. Neutrophil infiltration was evaluated by the measurement of tissue myeloperoxidase (MPO) activity, while the tumor necrosis factor-alpha (TNF-alpha) levels were measured in serum samples. Skin tissues were also examined microscopically. Severe skin scald injury (30% of total body surface area) caused significant decreases in GSH levels of the liver and intestinal tissues (p<0.01-<0.001), while MDA levels were significantly (p<0.01-p<0.001) increased at post-burn 6 and 48 h. Both local and systemic beta-glucan treatments significantly reversed (p<0.01-p<0.001) the elevations in MDA levels, while reduced GSH levels were reversed back to control levels (p<0.01-p<0.001); and the raised MPO levels were significantly decreased (p<0.05-p<0.001). The results indicate that both systemic and local administration of beta-glucan were effective against burn-induced oxidative tissue damage in the rat. beta-glucans, besides their immunomodulatory effects, have additional antioxidant properties. Therefore, beta-glucans merit consideration as therapeutic agents in the treatment of burn injuries.

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.

Protective effect of beta-glucan against oxidative organ injury in a rat model of sepsis

Sepsis leads to various organ damage and dysfunction. One of the underlying mechanisms is thought to be the oxidative damage due to the generation of free radicals. In this study, we investigated the putative protective role of beta-glucan against sepsis-induced oxidative organ damage. Sepsis was induced by caecal ligation and puncture (CLP) in Wistar albino rats. Sham operated (control) and sepsis groups received saline or beta-glucan (50 mg/kg, po) once daily for 10 days and 30 min prior to and 6 h after the CLP. Sixteen hours after the surgery, rats were decapitated and the biochemical changes were determined in the brain, diaphragm, kidney, heart, liver and lung tissues using malondialdehyde (MDA) content - an index of lipid peroxidation - glutathione (GSH) levels - a key antioxidant - and myeloperoxidase (MPO) activity - an index of neutrophil infiltration. Serum TNF-alpha levels were assessed by RIA method. Tissues were also examined under light microscope to evaluate the degree of sepsis-induced damage. The results demonstrate that sepsis significantly decreased GSH levels and increased the MDA levels and MPO activity (p<0.05-p<0.001) causing oxidative damage. Elevated plasma TNF-alpha levels in septic rats significantly reduced to control levels in beta-glucan treated rats. Since beta-glucan administration reversed these oxidant responses, it seems likely that beta-glucan protects against sepsis-induced oxidative organ injury.

Prevention of intraperitoneal adhesion formation using beta-glucan after ileocolic anastomosis in a rat bacterial peritonitis model

BACKGROUND

To investigate the effects of beta-glucan on intraabdominal abscess and adhesion formation after ileocolic anastomosis in a rat bacterial peritonitis model.

METHODS

Sixty male Wistar rats were used in this study. Bacterial peritonitis was induced by performing a cecal ligation and puncture (CLP). On the first day, abdomen was reopened and peritoneal fluid samples were taken for microbiological examination. Thereafter, cecum was resected and ileocolic anastomosis was made. Group 1 rats were given 1 mL of normal saline as a placebo. Group 2 and group 3 rats were given beta-D-glucan 2 mg/kg by intramuscularly; 1 mg of beta-1,3-D-glucanase was administered to group 3 rats just after the use of beta-D-glucan. Half of each group were killed at day 7 and at day 21, respectively. Adhesions were scored and the presence of intraabdominal abscesses was noted.

RESULTS

One day after CLP, microbiological examination showed polymicrobial bacterial peritonitis. Five (8%) of the 60 animals died owing to sepsis. One week after CLP, in two rats in each group developed abscess formation. Three weeks after CLP, abscess formation was observed in only one rat in each group. The rats treated with the beta-glucan had significantly lower adhesion scores than did the saline-treated rats (P = 0.008 at one week; P = 0.001 at 3 weeks). Administration of beta-glucanase inhibited beta-glucan activity and resulted in more adhesions (P = 0.022 at 1 week; P = 0.006 at 3 weeks).

CONCLUSIONS

Although the use of beta-glucan after ileocolic anastomosis in rats with experimentally developed intraabdominal sepsis does not have any significantly effect on mortality and abscess formation, beta-glucan is capable of reducing the frequency of adhesion. This effect of beta-glucan has been prevented with beta-glucanase

Beta-glucan, extracted from oat, enhances disease resistance against bacterial and parasitic infections

The effect of beta-glucan, extracted from oats, on the enhancement of resistance to infections caused by Staphylococcus aureus and Eimeria vermiformis was studied in mice. In vitro study using macrophages isolated from the peritoneal cavity showed that beta-glucan treatment significantly enhanced phagocytic activity. In vivo study further demonstrated that beta-glucan treatment induced a significant (P<0.05) protection against the challenge with 5 x 10(8) of S. aureus in mice. Fecal oocyst shedding in the C57BL/6 mice infected with E. vermiformis was diminished by beta-glucan treatment by 39.6% in intraperitoneal and 28.5% in intragastric group compared to non-treated control. Patency period was shorter and antigen (sporozoites and merozoites) specific antibodies were significantly (P<0.05-0.01) higher in beta-glucan-treated group compared to non-treated control group. There were an increasing number of splenic IFN-gamma-secreting cells in glucan-treated group via intraperitoneal route, which might be responsible for the enhancement of the disease resistance. Glucan treatment was able to effectively change the lymphocytes population (Thy 1.2(+), CD4(+) and CD8(+) cells) in the mesenteric lymph nodes and Peyer's patches in mice infected with E. vermiformis. In conclusion, the oral or parenteral oat beta-glucan treatment enhanced the resistance to S. aureus or E. vermiformis infection in the mice.

Enhanced neutrophil emigration and Porphyromonas gingivalis reduction following PGG-glucan treatment of mice

Periodontal disease is the consequence of a mixed Gram-negative infection in the gingival sulcus and has been associated with deficits in the neutrophil response. A novel, and heretofore untested, alternative approach to therapy is the use of biological-response modulators that enhance the neutrophil response. Poly-beta1-6-glucotriosyl-beta1-3-glucopyranose glucan (PGG-glucan) is an immunomodulator, derived from yeast, which specifically enhances neutrophil priming, phagocytosis and bacterial killing while failing to induce inflammatory cytokine expression. The hypothesis tested was that PGG-glucan could enhance host resistance to a Gram-negative periodontal pathogen, Porphyromonas gingivalis. Chambers were implanted subcutaneously in the dorsolumbar region of C57BL/6J mice and allowed to heal for 14 days. PGG-glucan was administered subcutaneously to one-half of the animals and saline to the other half. In the first set of experiments the chambers were inoculated with P. gingivalis (A7436) at 4 x 10 (6), 4 x 10 (7), and 4 x 10 (8) colony-forming units (CFU). In the second set of experiments the chambers were inoculated with 5 x 10 (8) CFU of either P. gingivalis or Streptococcus sanguis, a Gram-positive oral microbe that is not periodontopathic. Chambers were sampled over the following 2 weeks. The results demonstrated that: (1). bacterial CFU and neutrophils increased with increasing bacterial inoculum (P<0.02); (2). bacterial CFU were lower in the PGG-glucan-treated animals than in the saline controls (P<0.02); and (3). neutrophil counts were higher in the PGG-glucan-treated animals than in the saline controls (P<0.01). These results indicate that PGG-glucan significantly enhances neutrophil emigration and bacterial killing, thus decreasing the bacterial infection in this model system.

Immunostimulant oxidized β-glucan conjugates

beta-Glucans are polysaccharides that act as nonspecific immune system stimulants. However, many beta-Glucans are sparingly soluble in water. This work describes an oxidative procedure, which solubilizes the beta-Glucan from Saccharomyces cerevisiae and maintains its immunostimulatory properties. Furthermore, the carboxylates at the site of oxidation allow for the conjugation of small molecule immunostimulants. Both the parent oxidized beta-glucan and its conjugates with O-beta-alanyl-5-[6-(N,N'-dimethylamino)purin-9-yl]pentanol stimulate cytotoxic T-lymphocytes (CTLs), B cells and macrophages. In addition, they both stimulate natural killer (NK) cells, a property which the small molecule purine does not possess.

Glucans exhibit weak antioxidant activity, but stimulate macrophage free radical activity

Polymeric carbohydrates have been reported to modulate inflammatory responses in vitro and in vivo. Previous reports suggest that certain carbohydrate polymers, such as (1-->3)-beta-D-glucans, may possess free radical scavenging activity. If glucans are free radical scavengers then it might explain, in part, the ability of these ligands to modulate inflammatory responses. The present study examined the free radical scavenging activity of a variety of carbohydrate polymers and the effect of the polymers on free radical levels in a murine macrophage cell line. All of the carbohydrates exhibited concentration dependent antioxidant effects (EC(50) range = 807 to 43 microg/ml). However, the antioxidant activity for the carbohydrates was modest in comparison with PDTC (EC(50) = 0.13 microg/ml) and the carbohydrate concentration required for antioxidant activity was high (x EC(50) = 283 microg/ml). The antioxidant ability of the polymers was greater (p < .05) than their monosaccharide constituents, i.e., dextrose EC(50) = 807 vs. glucan sulfate EC(50) = 43 microg/ml. Coincubation of glucans with murine J774a.1 cells increased free radical levels when compared to controls. Therefore, the weak free radical scavenging activity of glucan polymers cannot explain their modulatory effect on inflammatory responses in tissue culture and/or disease models of inflammation.

Polysaccharide immunomodulators as therapeutic agents: structural aspects and biologic function

Polysaccharide immunomodulators were first discovered over 40 years ago. Although very few have been rigorously studied, recent reports have revealed the mechanism of action and structure-function attributes of some of these molecules. Certain polysaccharide immunomodulators have been identified that have profound effects in the regulation of immune responses during the progression of infectious diseases, and studies have begun to define structural aspects of these molecules that govern their function and interaction with cells of the host immune system. These polymers can influence innate and cell-mediated immunity through interactions with T cells, monocytes, macrophages, and polymorphonuclear lymphocytes. The ability to modulate the immune response in an appropriate way can enhance the host's immune response to certain infections. In addition, this strategy can be utilized to augment current treatment regimens such as antimicrobial therapy that are becoming less efficacious with the advent of antibiotic resistance. This review focuses on recent studies that illustrate the structural and biologic activities of specific polysaccharide immunomodulators and outlines their potential for clinical use.

Polysaccharide immunomodulators as therapeutic agents: structural aspects and biologic function

Polysaccharide immunomodulators were first discovered over 40 years ago. Although very few have been rigorously studied, recent reports have revealed the mechanism of action and structure-function attributes of some of these molecules. Certain polysaccharide immunomodulators have been identified that have profound effects in the regulation of immune responses during the progression of infectious diseases, and studies have begun to define structural aspects of these molecules that govern their function and interaction with cells of the host immune system. These polymers can influence innate and cell-mediated immunity through interactions with T cells, monocytes, macrophages, and polymorphonuclear lymphocytes. The ability to modulate the immune response in an appropriate way can enhance the host's immune response to certain infections. In addition, this strategy can be utilized to augment current treatment regimens such as antimicrobial therapy that are becoming less efficacious with the advent of antibiotic resistance. This review focuses on recent studies that illustrate the structural and biologic activities of specific polysaccharide immunomodulators and outlines their potential for clinical use.

Activation of a rel-A/CEBP-beta-related transcription factor heteromer by PGG-glucan in a murine monocytic cell line

PGG-Glucan is a soluble beta-glucan immunomodulator that enhances a variety of leukocyte microbicidal activities without activating inflammatory cytokines. Although several different cell surface receptors for soluble (and particulate) beta-glucans have been described, the signal transduction pathway(s) used by these soluble ligands have not been elucidated. Previously we reported that PGG-Glucan treatment of mouse BMC2.3 macrophage cells activates a nuclear factor kappa-B-like (NF-kappaB) transcription factor complex containing subunit p65 (rel-A) attached to an unidentified cohort. In this study, we identify the cohort to be a non-rel family member: a CCAAT enhancer-binding protein-beta (C/EBP-beta)-related molecule with an apparent size of 48 kDa, which is a different protein than the previously identified C/EBP-beta p34 also present in these cells. C/EBP-beta is a member of the bZIP family whose members have previously been shown to interact with rel family members. This rel/bZIP heteromer complex activated by PGG-Glucan is different from the p65/p50 rel/rel complex induced in these cells by lipopolysaccharide (LPS). Thus, our data demonstrate that PGG-Glucan uses signal transduction pathways different from those used by LPS, which activates leukocyte microbicidal activities and inflammatory cytokines. We further show that heteromer activation appears to use protein kinase C (PKC) and protein tyrosine kinase (PTK) pathways, but not mitogen-activated protein kinase p38. Inhibitor kappa-B-alpha (IkappaB-alpha) is associated with the heteromer; this association decreases after PGG-Glucan treatment. These data are consistent with a model whereby treatment of BMC2.3 cells with PGG-Glucan activates IkappaB-alpha via PKC and/or PTK pathways, permitting translocation of the rel-A/CEBP-beta heteromer complex to the nucleus and increases its DNA-binding affinity.

Effect of administration of oat beta-glucan on immune parameters of healthy and immunosuppressed beef steers

In order to assess the effect of oat beta-glucan (ObetaG) administration on immune parameters of beef steers, 3 experiments were carried out. In experiment 1, the in vitro effect of ObetaG on the proliferation of blood lymphocytes, with or without the presence of dexamethasone (DXM), was evaluated. In experiment 2, groups of 12 healthy steers were administered ObetaG or saline solution and immunized with ovalbumin (OVA). Immune parameters studied included IgG antibody levels to OVA, proliferation responses of blood lymphocytes to OVA, and blood leukocyte differential cell counts. For experiment 3, groups of 10 steers were treated with ObetaG and DXM, DXM only, or saline solution, and immunized with OVA and keyhole limpet hemocyanin (KLH). Serum antibody responses to OVA and KLH, serum IgG concentration levels, blastogenic responses of blood lymphocytes to OVA and KLH, differential blood leukocyte numbers, and iron and zinc concentration in serum were tested to evaluate the effect of ObetaG to overcome immunosuppression. The in vitro treatment of naive blood lymphocytes with ObetaG did not increase their ability to proliferate; however, when ObetaG was added to cultures of DXM-treated lymphocytes, a significant (P < 0.05 to P < 0.001) reversion of the immunosuppressive effect of DXM occurred. Administration of ObetaG to clinically healthy steers did not induce significant changes on any of the immune parameters studied. The administration of ObetaG to DXM-treated steers provoked, on Day 25, a significant increase in IgG anti-OVA (P < 0.01) and anti-KLH (P < 0.05) responses vs the DXM only group. On Day 25, the specific proliferation responses of lymphocytes, to both OVA and KLH, were significantly increased (P < 0.05) in ObetaG+DXM group compared to DXM group. On Day 4, a significant increase in the number of leukocytes (P < 0.01) and neutrophils (P < 0.001), and a significant decrease in the number of monocytes (P < 0.05) were observed in the group treated with DXM only compared to ObetaG+DXM group. No significant differences were observed in iron and zinc concentration between ObetaG+DXM and DXM groups. These results indicated that ObetaG did not influence immune responses of naive cells in vitro or of healthy steers in vivo; however, when cells or animals were treated with DXM, ObetaG significantly restored some of the specific and non-specific immune parameters studied.