Interleukin-12- and interferon-gamma-mediated natural killer cell activation by Agaricus blazei Murill

Polysaccharide Isolated from Agaricus blazei Murill Alleviates Intestinal Ischemia/Reperfusion Injury through Regulating Gut Microbiota and Mitigating Inflammation in Mice

Intestinal ischemia-reperfusion (I/R) injury is a serious disease in medical settings, and gut dysbiosis is a major contributor to its development. Polysaccharides from Agaricus blazei Murill (ABM) showed a range of pharmacological activities, yet no studies assessed the potential of ABM polysaccharides for alleviating intestinal I/R injury. Here, we purified a major polysaccharide (ABP1) from an ABM fruit body and subsequently tested its potential to mitigate intestinal I/R injury in a mouse model of temporary superior mesenteric artery occlusion. The results reveal that ABP1 pretreatment enhances gut barrier function via upregulation of the expression of tight junction proteins such as ZO-1 and occludin. Additionally, ABP1 intervention reduces the recruitment of neutrophils and the polarization of M1 macrophages and limits inflammation by blocking the assembly of the NLRP3 inflammasome. Moreover, the role of ABP1 in regulating the gut microbiota was confirmed via antibiotic treatment. The omics data reveals that ABP1 reprograms gut microbiota compositions, characterized by a decrease of Proteobacteria and an increase of Lachnospiraceae and Lactobacillaceae, especially the SCFA-producing genera such as Ligilactobacillus and Blautia. Overall, this work highlights the therapeutic potential of ABP1 against intestinal I/R injury, which mainly exhibits its effects via regulating the gut microbiota and suppressing the overactivated inflammation response.

Agaricus subrufescens fermented rye affects the development of intestinal microbiota, local intestinal and innate immunity in suckling-to-nursery pigs

BACKGROUND

Agaricus subrufescens is considered as one of the most important culinary-medicinal mushrooms around the world. It has been widely suggested to be used for the development of functional food ingredients to promote human health ascribed to the various properties (e.g., anti-inflammatory, antioxidant, and immunomodulatory activities). In this context, the interest in A. subrufescens based feed ingredients as alternatives for antibiotics has also been fuelled during an era of reduced/banned antibiotics use. This study aimed to investigate the effects of a fermented feed additive -rye overgrown with mycelium (ROM) of A. subrufescens-on pig intestinal microbiota, mucosal gene expression and local and systemic immunity during early life. Piglets received ROM or a tap water placebo (Ctrl) perorally every other day from day 2 after birth until 2 weeks post-weaning. Eight animals per treatment were euthanized and dissected on days 27, 44 and 70.

RESULTS

The results showed ROM piglets had a lower inter-individual variation of faecal microbiota composition before weaning and a lower relative abundance of proteobacterial genera in jejunum (Undibacterium and Solobacterium) and caecum (Intestinibacter and Succinivibrionaceae_UCG_001) on day 70, as compared to Ctrl piglets. ROM supplementation also influenced gut mucosal gene expression in both ileum and caecum on day 44. In ileum, ROM pigs showed increased expression of TJP1/ZO1 but decreased expression of CLDN3, CLDN5 and MUC2 than Ctrl pigs. Genes involved in TLR signalling (e.g., TICAM2, IRAK4 and LY96) were more expressed but MYD88 and TOLLIP were less expressed in ROM pigs than Ctrl animals. NOS2 and HIF1A involved in redox signalling were either decreased or increased in ROM pigs, respectively. In caecum, differentially expressed genes between two groups were mainly shown as increased expression (e.g., MUC2, PDGFRB, TOLLIP, TNFAIP3 and MYD88) in ROM pigs. Moreover, ROM animals showed higher NK cell activation in blood and enhanced IL-10 production in ex vivo stimulated MLN cells before weaning.

CONCLUSIONS

Collectively, these results suggest that ROM supplementation in early life modulates gut microbiota and (local) immune system development. Consequently, ROM supplementation may contribute to improving health of pigs during the weaning transition period and reducing antibiotics use.

Immunomodulatory functional foods and their molecular mechanisms

The immune system comprises a complex group of processes that provide defense against diverse pathogens. These defenses can be divided into innate and adaptive immunity, in which specific immune components converge to limit infections. In addition to genetic factors, aging, lifestyle, and environmental factors can influence immune function, potentially affecting the susceptibility of the host to disease-causing agents. Chemical compounds in certain foods have been shown to regulate signal transduction and cell phenotypes, ultimately impacting pathophysiology. Research has shown that the consumption of specific functional foods can stimulate the activity of immune cells, providing protection against cancer, viruses, and bacteria. Here, we review a number of functional foods reported to strengthen immunity, including ginseng, mushrooms, chlorella, and probiotics (Lactobacillus plantarum). We also discuss the molecular mechanisms involved in regulating the activity of various types of immune cells. Identifying immune-enhancing functional foods and understanding their mechanisms of action will support new approaches to maintain proper health and combat immunological diseases.

Evidence is building to support the idea that specific ‘functional foods’ can stimulate the activity of cells and signaling systems of the immune system to provide protection against cancer, viruses and bacteria. Sanguine Byun and colleagues at Yonsei University in Seoul, South Korea, review research into a range of functional foods, foods thought to have health benefits beyond their nutritional value. These include ginseng, mushrooms, the green algae called Chlorella and the probiotic bacteria Lactobacillus plantarum. They also consider individual components of foods such as poly-gamma-glutamate, a natural polymer made by bacteria. A wide body of research is revealing diverse molecular mechanisms through which biochemicals in functional foods can modulate different aspects of the immune system. These include effects on both non-specific innate immunity and adaptive immunity, which targets specific invading pathogens and diseased cells.

Fermented rye with Agaricus subrufescens and mannan-rich hydrolysate based feed additive to modulate post-weaning piglet immune response

BACKGROUND

The process of weaning in piglets is often associated with an increased inflammation response in the intestine and compromised intestinal integrity and morphology, favoring a delay in intestinal maturation and a predisposal to diseases. Research has shown the potential of different nutritional strategies to reduce the production of pro-inflammatory cytokines, with the main goal to manipulate health and performance of pigs. Promising examples of nutritional strategies are fungal fermented products and their derivatives which are described to contain several compounds that may play a role in gastrointestinal health and pathogenic bacteria control. Products from Agaricus subrufescens mushroom are reported to contain prophylactic and therapeutic properties including antimicrobial and immunomodulatory properties.

RESULTS

This study analysed the post-weaning immune status in intestinal tissue and blood of piglets, with the objective to evaluate the gastrointestinal health and immune modulation response induced by a blend of mannan-rich hydrolyzed copra meal and fermented rye with A. subrufescens. Intestinal histomorphology demonstrated a villus height reduction in jejunum and increase in ileum on day 15, while increased villous height in jejunum and ileum on day 30. The results showed that in post-weaning piglets, the feed additive stimulates an immunomodulation effect most evident at 15 days post-weaning, with significant lower expression of cytokines Interferon (IFN) γ, Interleukin (IL) 1α, IL-1β, IL-6, IL-8, IL-10 and Transforming Growth Factor (TGF) β in jejunum, accompanied with an increase in peripheral blood mononuclear cells (PBMC) cytokine gene expression of IL-1β, IL-6, IL-8, IL-10, IL-12p35 (IL-12α), IL-12p40 (IL-12β), Tumor Necrosis Factor (TNF) α, IFN-α, and TGF-β. In piglets fed the feed additive, the quantity of Immunoglobulin (Ig) A producing cells in jejunum, ileum was reduced on day 15 and 30 post-weaning, and on day 30 and 45 post-weaning in colon tissue. Natural Killer (NK) cells count in blood were increased on day 15 post-weaning in the piglets fed the feed additive.

CONCLUSION

This study implies the potential of the blend including mannan-rich hydrolyzed copra meal and fermented rye with A. subrufescens on immune modulation in the intestine of post-weaning piglets.

Nicotinamide mononucleotide augments the cytotoxic activity of natural killer cells in young and elderly mice

Nicotinamide mononucleotide (NMN), a key nicotinamide adenine dinucleotide (NAD⁺) intermediate, has been shown to ameliorate various pathologies in elderly mouse disease models. Natural killer (NK) cells are important innate immune cells; however, their functions decline with aging. In this study, we examined the effect of NMN treatment on NK cells in mice. Intraperitoneal administration of NMN augmented NK cell cytotoxic activity in both young and elderly B6 mice as well as young BALB/c mice. Oral administration of NMN also increased NK cell cytotoxicity in elderly B6 and BALB/c mice. However, the NK cell population was not increased in the mice whose NK cell cytotoxic activity was activated by NMN. Interestingly, NMN administration did not augment NK cell cytotoxic activity in IFN-γ deficient mice. These results suggest that NMN administration augments NK cell cytotoxic activity, but not cell number, in a manner dependent on IFN-γ in both young and elderly mice.

A water-soluble derivative of propolis augments the cytotoxic activity of natural killer cells

ETHNOPHARMACOLOGICAL RELEVANCE

Propolis, a resinous material collected from numerous plants by honeybees, has historically been used as a health-promoting food. Recently, due to its potential anti-tumor effects, use of propolis has been proposed as an adjuvant therapy to chemotherapy; however, the effects of propolis on immune responses remain unclear.

AIM OF THE STUDY

In this study, we examined the effects of the oral ingestion of propolis on natural killer (NK) cell activity, which is important in immune surveillance against cancer and viral infections. In addition, we assessed the effects of the major components of the water-soluble powder derivative of propolis (WPP).

MATERIALS AND METHODS

C57BL/6 (B6) wild-type (WT) and RAG 2-deficient (RAG^-/-) mice and BALB/c WT, interferon (IFN)-γ-deficient (IFN-γ^-/-), IFN-γ receptor-deficient (IFN-γR^-/-) and RAG^-/- mice were orally administered WPP or its major components. NK cell populations and cytotoxic activity were then examined by flow cytometry and ⁵¹Cr release assay, respectively.

RESULTS

While the cytotoxic activity of NK cells was increased following administration of 100 mg/kg/day of WPP for 7 days or 200 or 500 mg/kg/day of WPP for 4 days in WT mice, the proportions of NK cell populations were unaltered. Similar activation of NK cell cytotoxicity was observed when RAG^-/-, but not IFN-γ^-/- or IFN-γR^-/-, mice were orally administered 200 mg/kg/day of WPP for 4 days. Oral ingestion of artepillin C or p-coumaric acid, but not drupanin, augmented NK cell cytotoxicity in a manner similar to WPP and to the mixture of these three components.

CONCLUSION

These results suggest that oral ingestion of WPP enhances NK cell cytotoxic activity, but not proliferation, in a manner dependent on IFN-γ and without the contribution of acquired immune responses. Further, artepillin C or p-coumaric acid, but not drupanin, may be the components responsible for this augmentation of NK cell cytotoxicity. These findings suggest the possible utility of WPP as a therapeutic for prevention of cancer development and against viral infection through NK cell activation.

Species difference in reactivity to lignin-like enzymatically polymerized polyphenols on interferon-γ synthesis and involvement of interleukin-2 production in mice

Recent studies have revealed that lignin-like polymerized polyphenols can activate innate immune systems. In this study, we aimed to evaluate whether these polymerized polyphenols could activate leukocytes from different murine strains. Splenocytes from 12 mouse strains were investigated. Our results revealed species differences in reactivity to phenolic polymers on interferon-γ (IFN-γ) release. Mice that possessed the H2(a) or H2(k) haplotype antigens were the highly responsive strains. To clarify these different points in soluble factors, multiplex cytokine profiling analysis was carried out and we identified interleukin (IL)-2 as a key molecule for IFN-γ induction by polymerized polyphenols. Furthermore, inhibition of IL-2 and IL-2Rα by neutralizing antibodies significantly decreased cytokine production in the highly responsive mice strains. Our results indicate that species difference in reactivity to phenolic polymers is mediated by adequate release of IL-2 and its receptor, IL-2Rα.

Efeito da extração de compostos fenólicos sobre a atividade antioxidante e antibacteriana in vitro de cogumelo-do-sol

RESUMO: O cogumelo-do-sol (Agaricus blazei Murril) é amplamente consumido, por conta de suas propriedades medicinais. Este estudo teve como objetivo determinar a atividade antioxidante e antibacteriana in vitro dos extratos de cogumelo do sol, mediante diferentes tempos e temperaturas de extração. As amostras foram analisadas quanto à composição centesimal, determinação do teor de fenólicos totais e atividade antioxidante e antibacteriana in vitro. Os resultados demonstram que esse tipo de cogumelo aparece como um agente antioxidante potencial, obtendo-se melhores resultados na temperatura de 70ºC durante 60 minutos de extração hidroetanólica. Esse extrato não aponta atividade antibacteriana para os micro-organismos em teste.

Interferon-γ-Mediated Natural Killer Cell Activation by an Aqueous Panax ginseng Extract

Panax ginseng extracts are used in traditional herbal medicines, particularly in eastern Asia, but their effect on natural killer (NK) cell activity is not completely understood. This study aimed to examine the effects of P. ginseng extracts on the cytotoxic activity of NK cells. We orally administered P. ginseng extracts or ginsenosides to wild-type (WT) C57BL/6 (B6) and BALB/c mice and to B6 mice deficient in either recombination activating gene 2 (RAG-2) or interferon-γ (IFN-γ). We then tested the cytotoxic activity of NK cells (of spleen and liver mononuclear cells) against NK-sensitive YAC-1 cells. Oral administration of P. ginseng aqueous extract augmented the cytotoxicity of NK cells in WT B6 and BALB/c mice and in RAG-2-deficient B6 mice, but not in IFN-γ-deficient B6 mice. This effect was only observed with the aqueous extract of P. ginseng. Interestingly, the ginsenosides Rb1 and Rg1 did not augment NK cell cytotoxicity. These results demonstrated that the aqueous P. ginseng extract augmented NK cell activation in vivo via an IFN-γ-dependent pathway.

Polysaccharide Agaricus blazei Murill stimulates myeloid derived suppressor cell differentiation from M2 to M1 type, which mediates inhibition of tumour immune-evasion via the Toll-like receptor 2 pathway

Gr-1(+) CD11b(+) myeloid-derived suppressor cells (MDSCs) accumulate in tumor-bearing animals and play a critical negative role during tumor immunotherapy. Strategies for inhibition of MDSCs are expected to improve cancer immunotherapy. Polysaccharide Agaricus blazei Murill (pAbM) has been found to have anti-cancer activity, but the underlying mechanism of this is poorly understood. Here, pAbM directly activated the purified MDSCs through inducing the expression of interleukin-6 (IL-6), IL-12, tumour necrosis factor and inducible nitric oxide synthase (iNOS), CD86, MHC II, and pSTAT1 of it, and only affected natural killer and T cells in the presence of Gr-1(+) CD11b(+) monocytic MDSCs. On further analysis, we demonstrated that pAbM could selectively block the Toll-like receptor 2 (TLR2) signal of Gr-1(+) CD11b(+) MDSCs and increased their M1-type macrophage characteristics, such as producing IL-12, lowering expression of Arginase 1 and increasing expression of iNOS. Extensive study showed that Gr-1(+) CD11b(+) MDSCs by pAbM treatment had less ability to convert the CD4(+) CD25(-) cells into CD4(+) CD25(+) phenotype. Moreover, result from selective depletion of specific cell populations in xenograft mice model suggested that the anti-tumour effect of pAbM was dependent on Gr-1(+ ) CD11b(+) monocytes, nether CD8(+) T cells nor CD4(+) T cells. In addition to, pAbM did not inhibit tumour growth in TLR2(-/-) mice. All together, these results suggested that pAbM, a natural product commonly used for cancer treatment, was a specific TLR2 agonist and had potent anti-tumour effects through the opposite of the suppressive function of Gr-1(+) CD11b(+) MDSCs.

Impact of dietary components on NK and Treg cell function for cancer prevention

An important characteristic of cancer is that the disease can overcome the surveillance of the immune system. A possible explanation for this resistance arises from the ability of tumor cells to block the tumoricidal activity of host immune cells such as natural killer (NK) cells by inducing the localized accumulation of regulatory T (Treg) cells. Evidence exists that components in commonly consumed foods including vitamins A, D, and E, water-soluble constituents of mushrooms, polyphenolics in fruits and vegetables, and n-3 fatty acids in fish oil can modulate NK cell activities, Treg cell properties, and the interactions between those two cell types. Thus, it is extremely important for cancer prevention to understand the involvement of dietary components with the early stage dynamics of interactions among these immune cells. This review addresses the potential significance of diet in supporting the function of NK cells, Treg cells, and the balance between those two cell types, which ultimately results in decreased cancer risk.

Induction of a T-Helper 1 (Th1) immune response in mice by an extract from the Pleurotus eryngii (Eringi) mushroom

To assess the effect of edible mushroom extracts on the induction of T-helper 1 (Th1) immunity, we examined differences in interferon-gamma (IFN-γ) and interleukin (IL)-4 production in mice induced by hot-water extracts of 15 species of edible mushroom. Extracts from Agaricus bisporus, Flammulina velutipes, Hypsizigus marmoreus, Lentinula edodes, and Lyophyllum decastes induced both IFN-γ and IL-4 production in mice, whereas extracts from Pleurotus ostreatus only induced IL-4. In contrast, extracts from Agaricus blazei, Grifola frondosa, Morchella esculenta, Pholiota nameko, Pleurotus citrinopileatus, and Pleurotus eryngii induced only IFN-γ production. In particular, the extract from P. eryngii induced high levels of IFN-γ and reduced levels of IL-4. We further investigated the use of a trial immunogen using the P. eryngii extract as a Th1 immunostimulator. An oil-in-water emulsion of the hot-water extract from P. eryngii (immunostimulator) and ovalbumin (OVA; antigen) was used as a trial immunogen. This immunogen induced strong OVA-specific IgG2a antibody production in mice compared with the negative controls. In addition, OVA-specific IgG1 antibody levels were lower than those for the negative controls. Marked increases in serum IFN-γ levels and high-level production of IFN-γ in the culture supernatant from the CD4(+) spleen cells in the trial immunogen group mice were observed. Our results suggested that the hot-water extract from P. eryngii induced Th1 immunity by acting as an immunostimulator.

Agaricus brasiliensis-derived β-glucans exert immunoenhancing effects via a dectin-1-dependent pathway

Agaricus brasiliensis is a well-known medicinal mushroom. We have previously demonstrated that Agaricus-derived polysaccharides exhibit potent antitumor effects; however, the underlying mechanism(s) have not been elucidated yet. In this study, we examined the immunoenhancing activities of Agaricus extracts. Agaricus-derived polysaccharides were characterized as 1,6-β-glucan with a small amount of 1,3-β-glucan using anti-β-glucan antibody and nuclear magnetic resonance analysis. These polysaccharides strongly induced the production of various cytokines from both murine splenocytes and bone marrow-derived dendritic cells in the presence of exogenous granulocyte-macrophage colony-stimulating factor. Polysaccharide-induced cytokine production was significantly reduced in bone marrow-derived dendritic cells derived from dectin-1-deficient mice. Furthermore, a binding assay revealed that the Agaricus-derived polysaccharides can be recognized by dectin-1, a pivotal receptor for 1,3-β-glucan. Taken together, our results clearly indicate that the immunostimulation induced by Agaricus-derived polysaccharides is exerted, at least in part, via dectin-1 in combination with granulocyte-macrophage colony-stimulating factor.

The effect of enzymatically polymerised polyphenols on CD4 binding and cytokine production in murine splenocytes

High-molecular weight polymerised polyphenols have been shown to exhibit anti-influenza virus, anti-HIV, and anti-cancer activities. The purpose of this study was to evaluate the immunomodulating activities of enzymatically polymerised polyphenols, and to clarify the underlying mechanisms of their effects. The cytokine-inducing activity of the enzymatically polymerised polyphenols derived from caffeic acid (CA), ferulic acid (FA), and p-coumaric acid (CoA) was investigated using murine splenocytes. Polymerised polyphenols, but not non-polymerised polyphenols, induced cytokine synthesis in murine splenocytes. Polymerised polyphenols induced several cytokines in murine splenocytes, with interferon-γ (IFN-γ) and granulocyte-macrophage colony-stimulating factor (GM-CSF) being the most prominent. The underlying mechanisms of the effects of the polymerised polyphenols were then studied using neutralising antibodies and fluorescent-activated cell sorting (FACS) analysis. Our results show that polymerised polyphenols increased IFN-γ and GM-CSF production in splenocytes. In addition, the anti-CD4 neutralised monoclonal antibody (mAb) inhibited polymerised polyphenol-induced IFN-γ and GM-CSF secretion. Moreover, polymerised polyphenols bound directly to a recombinant CD4 protein, and FACS analysis confirmed that interaction occurs between polymerised polyphenols and CD4 molecules expressed on the cell surface. In this study, we clearly demonstrated that enzymatic polymerisation confers immunoactivating potential to phenylpropanoic acids, and CD4 plays a key role in their cytokine-inducing activity.

Agaricus subrufescens: A review

Medicinal mushrooms have currently become a hot issue due to their various therapeutic properties. Of these, Agaricus subrufescens, also known as the "almond mushroom", has long been valued by many societies (i.e., Brazil, China, France, and USA). Since its discovery in 1893, this mushroom has been cultivated throughout the world, especially in Brazil where several strains of A. subrufescens have been developed and used as health food and alternative medicine. This article presents up-to-date information on this mushroom including its taxonomy and health promoting benefits. Medicinal properties of A. subrufescens are emphasized in several studies which are reviewed here. In addition, safety issues concerning the use of this fungus will be discussed.

Effect of Agaricus brasiliensis-derived cold water extract on Toll-like receptor 2-dependent cytokine production in vitro

Agaricus brasiliensis (Agaricus blazei Murrill) is well known as a medicinal mushroom. Fruit body of A. brasiliensis is rich in β-glucan and has shown benefits for various diseases. Both hot and cold water extraction are traditional methods for intake of this mushroom extract. In the present study, we prepared cold water extract of the fruit body of A. brasiliensis (ACWS). The 1,3-β-glucan segment of this fraction was too small and did not interact with the 1,3-β-glucan receptor, dectin-1. However, ACWS could induce production of various cytokines including IL-6 from murine splenocytes. Therefore, we aimed to identify the receptor that modulates IL-6 production using ACWS. We focused our attention on Toll-like receptors (TLRs) and examined them as follows. (i) The interaction between TLRs and ACWS was screened using HEK293 cells transfected with TLR plasmid. (ii) IL-6 production from splenocytes induced by ACWS was inhibited by treatment of anti-TLR antibodies. (iii) Direct binding activity between TLR protein and ACWS was assessed by ELISA-like assay. ACWS was found to activate HEK293 cells via TLR2, 4 and 5. However, only anti-TLR2 monoclonal antibody suppressed IL-6 production from splenocytes. In addition, ACWS has the ability to bind directly to TLR2 protein. Accordingly, we suggest that fruit body of A. brasiliensis has some water-soluble TLR ligand complexes, and TLR2 on splenocytes strongly induces IL-6 production.

A Hypothesis: Supplementation with Mushroom-Derived Active Compound Modulates Immunity and Increases Survival in Response to Influenza Virus (H1N1) Infection

We hypothesize that the mushroom-derived active compound may be a potential strategy for increasing survival in response to influenza virus (H1N1) infection through the stimulation of host innate immune response. The validity of the hypothesis can be tested by immune response to influenza infection as seen through survival percentage, virus clearance, weight loss, natural killer cell cytotoxicity, Tumor Necrosis Factor-α (TNF-α) and Interferon-gamma (IFN-γ) levels, lytic efficiency in the spleens of mice and inducible nitric oxide synthase mRNA expressions in RAW 264.7 murine macrophage cells. The hypothesis may improve people's quality of life, reduce the medical cost of our healthcare system and eliminate people's fears of influenza outbreak.

Does the Agaricus blazei Murill mushroom have properties that affect the immune system? An integrative review

There has been a significant increase in the use of mushrooms for therapeutic and medicinal purposes, in particular, use of the species Agaricus blazei Murrill, a basidiomycota of Brazilian origin. The objective of this study was to identify scientific evidence regarding the influence of A. blazei Murrill on the immune system. We undertook an integrative review of indexed publications published between 2000 and 2009, using the following question as a guideline: "What evidence can be found in the literature regarding the influence of A. blazei Murrill on the immune system?" Fourteen studies verified that there is in vitro and in vivo research demonstrating this mushroom's influence on the immune system. All research was characterized as evidence level 7 (preclinical study [animals/in vitro]). The research shows that A. blazei Murrill functions through bioactive compounds via mechanisms that are not yet entirely clear, although it has been shown that they promote action on the innate and adaptive immunological response, activation of the complement system, and synthesis of pro- and anti-inflammatory cytokines and even aid in diapedesis. Despite broad scientific evidence demonstrating relevant immunomodulatory properties of A. blazei Murrill, randomized clinical trials with human subjects are still needed in order for the mushroom to be put into clinical practice.

Immunomodulatory dietary polysaccharides: a systematic review of the literature

BACKGROUND

A large body of literature suggests that certain polysaccharides affect immune system function. Much of this literature, however, consists of in vitro studies or studies in which polysaccharides were injected. Their immunologic effects following oral administration is less clear. The purpose of this systematic review was to consolidate and evaluate the available data regarding the specific immunologic effects of dietary polysaccharides.

METHODS

Studies were identified by conducting PubMed and Google Scholar electronic searches and through reviews of polysaccharide article bibliographies. Only articles published in English were included in this review. Two researchers reviewed data on study design, control, sample size, results, and nature of outcome measures. Subsequent searches were conducted to gather information about polysaccharide safety, structure and composition, and disposition.

RESULTS

We found 62 publications reporting statistically significant effects of orally ingested glucans, pectins, heteroglycans, glucomannans, fucoidans, galactomannans, arabinogalactans and mixed polysaccharide products in rodents. Fifteen controlled human studies reported that oral glucans, arabinogalactans, heteroglycans, and fucoidans exerted significant effects. Although some studies investigated anti-inflammatory effects, most studies investigated the ability of oral polysaccharides to stimulate the immune system. These studies, as well as safety and toxicity studies, suggest that these polysaccharide products appear to be largely well-tolerated.

CONCLUSIONS

Taken as a whole, the oral polysaccharide literature is highly heterogenous and is not sufficient to support broad product structure/function generalizations. Numerous dietary polysaccharides, particularly glucans, appear to elicit diverse immunomodulatory effects in numerous animal tissues, including the blood, GI tract and spleen. Glucan extracts from the Trametes versicolor mushroom improved survival and immune function in human RCTs of cancer patients; glucans, arabinogalactans and fucoidans elicited immunomodulatory effects in controlled studies of healthy adults and patients with canker sores and seasonal allergies. This review provides a foundation that can serve to guide future research on immune modulation by well-characterized polysaccharide compounds.

Screening for in vitro and in vivo antitumor activities of the mushroom Agaricus blazei

We have investigated the in vitro antitumor activity of the mushroom Agaricus blazei Murill on human cancer cell lines as well as its potential anticancer activity in a model of rat colon carcinogenesis. The in vitro anticancer analysis was performed using 9 human cancer cell lines incubated with organic and aqueous extracts of A. blazei. Antitumor activity was observed with the dichloromethane/methanol and hexanic extracts of A. blazei at 250 mu g/ml for all cancer cell lines tested. No antiproliferative/cytotoxic activities were detected for the aqueous, methanol, ethyl acetate, or n-butanolic extracts. In the in vivo analysis, crude A. blazei was given orally after carcinogen treatment in a rat medium-term study (20 weeks) of colon carcinogenesis using aberrant crypt foci (ACF) as biomarker. Male Wistar rats were given dimethylhydrazine (DMH) and then were fed A. blazei at 5% in the diet until Week 20. ACF were scored for number and crypt multiplicity. A. blazei intake did not suppress ACF development or crypt multiplicity induced by DMH. No differences in tumor incidence in the colon were observed among the DMH-treated groups. Our results indicate that employing A. blazei in the diet does not have a suppressive effect on colon carcinogenesis.

An extract of the medicinal mushroom Agaricus blazei Murill can protect against allergy

Background

Agaricus blazei Murill (AbM) is an edible Brazilian mushroom that has been used in traditional medicine for a range of diseases. It has been shown to have anti-infection and anti-tumor properties in the mouse, which are due to induction of Th1 responses. On the other hand, IgE-mediated allergy is induced by a Th2 response.

Objective

Since according to the Th1/Th2 paradigm an increased Th1 response may promote a reduced Th2 response, the aim was to examine whether AbM had anti-allergy effects.

Methods

A mouse model for allergy was employed, in which the mice were immunized s.c. with the model allergen ovalbumin (OVA). Additionally, the animals were given a mushroom extract, AndoSan™, mainly (82%) containing AbM, but also Hericium erinaceum (15%) and Grifola frondosa (3%), or PBS p.o. either a day before or 19 days after the immunization. The mice were sacrificed on day 26, and anti-OVA IgE (Th2 response) and IgG2a (Th1 response) antibodies were examined in serum and Th1, Th2 and Treg cytokines in spleen cells cultures.

Results

It was found that the AndoSan™ extract both when given either before or after OVA immunization reduced the levels of anti-OVA IgE, but not IgG2a, in the mice. There was a tendency to reduced Th2 relative to Th1 cytokine levels in the AndoSan™ groups.

Conclusion

This particular AbM extract may both prevent allergy development and be used as a therapeutical substance against established allergy.

The effects of whole mushrooms during inflammation

BACKGROUND

Consumption of edible mushrooms has been suggested to improve health. A number of isolated mushroom constituents have been shown to modulate immunity. Five commonly consumed edible mushrooms were tested to determine whether whole mushrooms stimulate the immune system in vitro and in vivo.

RESULTS

The white button (WB) extracts readily stimulated macrophage production of TNF-alpha. The crimini, maitake, oyster and shiitake extracts also stimulated TNF-alpha production in macrophage but the levels were lower than from WB stimulation. Primary cultures of murine macrophage and ovalbumin (OVA) specific T cells showed that whole mushroom extracts alone had no effect on cytokine production but co-stimulation with either lipopolysaccharide or OVA (respectively) induced TNF-alpha, IFN-gamma, and IL-1beta while decreasing IL-10. Feeding mice diets that contained 2% WB mushrooms for 4 weeks had no effect on the ex vivo immune responsiveness or associated toxicity (changes in weight or pathology of liver, kidney and gastrointestinal tract). Dextran sodium sulfate (DSS) stimulation of mice that were fed 1% WB mushrooms were protected from DSS induced weight loss. In addition, 2% WB feeding protected the mice from transient DSS induced colonic injury. The TNF-alpha response in the colon and serum of the DSS challenged and 2% WB fed mice was higher than controls.

CONCLUSION

The data support a model whereby edible mushrooms regulate immunity in vitro. The in vivo effects of edible mushrooms required a challenge with DSS to detect small changes in TNF-alpha and transient protection from colonic injury. There are modest effects of in vivo consumption of edible mushrooms on induced inflammatory responses. The result is not surprising since it would certainly be harmful to strongly induce or suppress immune function following ingestion of a commonly consumed food.

Lack of chemoprevention of dietary Agaricus blazei against rat colonic aberrant crypt foci

The mushroom Agaricus blazei (Ab) has been widely used in folk medicine to treat various diseases including cancer. No information is available on its possible protective effects on the development of colon cancer. The potential blocking effect of Ab intake on the initiation stage of colon carcinogenesis was investigated in a short-term (4-week) bioassay using aberrant crypt foci (ACF) as biomarker. Male Wistar rats were given four subcutaneous injections of the carcinogen 1,2-dimethylhydrazine (DMH, 40 mg/kg bw, twice a week), during 2 weeks to induce ACF. The diet containing Ab at 5% was given 2 weeks before and during carcinogen treatment to investigate the potential beneficial effects of this edible mushroom on DMH-induced ACF. All groups were killed at the end of the fourth week. The colons were analyzed for ACF formation in 1% methylene blue whole-mount preparations and for cell proliferation in histological sections immunohistochemically stained for the proliferating cell nuclear antigen (PCNA). All DMH-treated rats developed ACF mainly in the middle and distal colon. Agaricus blazei intake at 5% did not alter the number of ACF induced by DMH or the PCNA indices in the colonic mucosa. Thus, the results of the present study did not confirm a chemopreventive activity of Ab on the initiation stage of rat colon carcinogenesis.

The immunobiology of mushrooms

There has been enormous interest in the biologic activity of mushrooms and innumerable claims have been made that mushrooms have beneficial effects on immune function with subsequent implications for inhibition of tumor growth. The majority of these observations are anecdotal and often lack standardization. However, there remains considerable data on both in vitro and in vivo effects that reflect on the potential of mushroom compounds to influence human immunity. A number of these effects are beneficial but, unfortunately, many responses are still characterized based on phenomenology and there is more speculation than substance. With respect to tumor biology, although many neoplastic lesions are immunogenic, tumor antigens frequently are self antigens and induce tolerance and many patients with cancer exhibit suppressed immune responses, including defective antigen presentation. Therefore, if and when mushroom extracts are effective, they more likely function as a result of improved antigen presentation by dendritic cells than by a direct cytopathic effect. In this review we attempt to place these data in perspective, with a particular focus on dendritic cell populations and the ability of mushroom extracts to modulate immunity. There is, at present, no scientific basis for the use of either mushrooms or mushroom extracts in the treatment of human patients but there is significant potential for rigorous research to understand the potential of mushrooms in human disease and thence to focus on appropriate clinical trials to demonstrate effectiveness and/ or potential toxicity.