Immune recognition of fungal β-glucans

Cellular and molecular mechanisms of fungal β-(1→6)-glucan in macrophages

Over the last 40 yr, the majority of research on glucans has focused on β-(1→3)-glucans. Recent studies indicate that β-(1→6)-glucans may be even more potent immune modulators than β-(1→3)-glucans. Mechanisms by which β-(1→6)-glucans are recognized and modulate immunity are unknown. In this study, we examined the interaction of purified water-soluble β-(1→6)-glucans with macrophage cell lines and primary peritoneal macrophages and the cellular and molecular consequences of this interaction. Our results indicate the existence of a specific β-(1→6)-glucan receptor that internalizes the glucan ligand via a clathrin-dependent mechanism. We show that the known β-(1→3)-glucans receptors are not responsible for β-(1→6)-glucan recognition and interaction. The receptor-ligand uptake/interaction has an apparent dissociation constant (KD) of ∼ 4 µM, and was associated with phosphorylation of ERK and JNK but not IκB-α or p38. Our results indicate that macrophage interaction with β-(1→6)-glucans may lead to modulation of genes associated with anti-fungal immunity and recruitment/activation of neutrophils. In summary, we show that macrophages specifically bind and internalize β-(1→6)-glucans followed by activation of intracellular signaling and modulation of anti-fungal immune response-related gene regulation. Thus, we conclude that the interaction between innate immunity and β-(1→6)-glucans may play an important role in shaping the anti-fungal immune response.

Molecular Interactions of β-(1→3)-Glucans with Their Receptors

β-(1→3)-Glucans can be found as structural polysaccharides in cereals, in algae or as exo-polysaccharides secreted on the surfaces of mushrooms or fungi. Research has now established that β-(1→3)-glucans can trigger different immune responses and act as efficient immunostimulating agents. They constitute prevalent sources of carbons for microorganisms after subsequent recognition by digesting enzymes. Nevertheless, mechanisms associated with both roles are not yet clearly understood. This review focuses on the variety of elucidated molecular interactions that involve these natural or synthetic polysaccharides and their receptors, i.e., Dectin-1, CR3, glycolipids, langerin and carbohydrate-binding modules.

A proteomics perspective on viral DNA sensors in host defense and viral immune evasion mechanisms

The sensing of viral DNA is an essential step of cellular immune response to infections with DNA viruses. These human pathogens are spread worldwide, triggering a wide range of virus-induced diseases, and are associated with high levels of morbidity and mortality. Despite similarities between DNA molecules, mammalian cells have the remarkable ability to distinguish viral DNA from their own DNA. This detection is carried out by specialized antiviral proteins, called DNA sensors. These sensors bind to foreign DNA to activate downstream immune signaling pathways and alert neighboring cells by eliciting the expression of antiviral cytokines. The sensing of viral DNA was shown to occur both in the cytoplasm and in the nucleus of infected cells, disproving the notion that sensing occurred by simple spatial separation of viral and host DNA. A number of omic approaches, in particular, mass-spectrometry-based proteomic methods, have significantly contributed to the constantly evolving field of viral DNA sensing. Here, we review the impact of omic methods on the identification of viral DNA sensors, as well as on the characterization of mechanisms involved in host defense or viral immune evasion.

The macrophage galactose-type lectin-1 (MGL1) recognizes Taenia crassiceps antigens, triggers intracellular signaling, and is critical for resistance to this infection

C-type lectins are multifunctional sugar-binding molecules expressed on dendritic cells (DCs) and macrophages that internalize antigens for processing and presentation. Macrophage galactose-type lectin 1 (MGL1) recognizes glycoconjugates expressing Lewis X structures which contain galactose residues, and it is selectively expressed on immature DCs and macrophages. Helminth parasites contain large amounts of glycosylated components, which play a role in the immune regulation induced by such infections. Macrophages from MGL1^−/− mice showed less binding ability toward parasite antigens than their wild-type (WT) counterparts. Exposure of WT macrophages to T. crassiceps antigens triggered tyrosine phosphorylation signaling activity, which was diminished in MGL1^−/− macrophages. Following T. crassiceps infection, MGL1^−/− mice failed to produce significant levels of inflammatory cytokines early in the infection compared to WT mice. In contrast, MGL1^−/− mice developed a Th2-dominant immune response that was associated with significantly higher parasite loads, whereas WT mice were resistant. Flow cytometry and RT-PCR analyses showed overexpression of the mannose receptors, IL-4Rα, PDL2, arginase-1, Ym1, and RELM-α on MGL1^−/− macrophages. These studies indicate that MGL1 is involved in T. crassiceps recognition and subsequent innate immune activation and resistance.

β-glucans and eicosapolyenoic acids as MAMPs in plant-oomycete interactions: past and present

Branched β-1,3-glucans and the eicosapolyenoic acids (EP) are among the best characterized oomycete elicitors that trigger innate immune responses in plants. These elicitors were identified over three decades ago, and they were useful in the study of the sequence of physiological, biochemical and molecular events that induce resistance in plants. However, in spite of the cross-kingdom parallels where these molecules are well-characterized as immune system modulators in animals, their perception and modes of action in plants remains obscure. Oomycetes are among the most important plant pathogens, responsible for diseases that devastate crops, ornamentals, and tree species worldwide. With the recent interest and advances in our understanding of innate immunity in plants, and the redefining of many of the classical elicitors as microbe-associated molecular patterns (MAMPs), it seems timely and important to reexamine β-glucans and EP using contemporary approaches. In this review, we highlight early studies of β-glucans and EP, discuss their roles as evolutionarily conserved signals, and consider their action in relation to current models of MAMP-triggered immunity.

Effect of maternal supplementation with seaweed extracts on growth performance and aspects of gastrointestinal health of newly weaned piglets after challenge with enterotoxigenic Escherichia coli K88

In the present study, a 2 × 2 factorial arrangement was conducted to investigate the effect of maternal supplementation with seaweed extracts ( - SWE v. +SWE, n 20) from day 83 of gestation until weaning (day 28) on post-weaning (PW) growth performance, faecal score, faecal enterotoxigenic Escherichia coli (ETEC) toxin quantification, intestinal histology and cytokine mRNA of unchallenged and ETEC-challenged pigs. Pigs were ETEC challenged on day 9 PW. There was a maternal treatment × challenge (SWE × ETEC) interaction effect on growth performance and faecal score (P< 0.05). Pigs from SWE-supplemented sows and ETEC-challenged (SE) had higher average daily gain (ADG) during 0-13 d PW and reduced faecal score during 0-72 h post-challenge than those from basal-fed sows and ETEC-challenged (BE) (P< 0.05). However, there was no difference between unchallenged pigs from the SWE-supplemented sows (SC) and basal-fed sows (BC) (P>0.10). Pigs from the SWE-supplemented sows had reduced heat-labile enterotoxin gene copy numbers than those from the basal-fed sows (P< 0.05). Maternal SWE supplementation increased the villus height in the ileum of pigs (P< 0.05). There was a SWE × ETEC interaction effect (P< 0.05) on IL-6 mRNA and a SWE × gastrointestinal (GI) region interaction effect (P< 0.05) on transforming growth factor-β1 (TGF-β1) and TNF-α mRNA. IL-6 mRNA was down-regulated in SC pigs than BC pigs (P< 0.05). However, there was no difference in IL-6 mRNA between SE and BE pigs. The mRNA of TGF-β1 and TNF-α was down-regulated in the colon of pigs from the SWE-supplemented sows compared with those from the basal-fed sows (P< 0.05). However, there was no difference in TGF-β1 and TNF-α mRNA in the ileum between the pigs from the SWE-supplemented sows and basal-fed sows. In conclusion, maternal SWE supplementation improves ADG and the aspects of GI health of weaned pigs following an ETEC challenge.

Interaction among the vacuole, the mitochondria, and the oxidative stress response is governed by the transient receptor potential channel in Candida albicans

Candida albicans is one of the most important opportunistic pathogens, causing both mucosal candidiasis and life-threatening systemic infections. To survive in the host immune defense system, this pathogen uses an elaborate signaling network to recognize and respond to oxidative stress, which is essential for its pathogenicity. However, the exact mechanisms that this fungus employs to integrate the oxidative stress response (OSR) with functions of various organelles remain uncharacterized. Our previous work implicated a connection between the calcium signaling system and the OSR. In this study, we find that the vacuolar transient receptor potential (TRP) channel Yvc1, one of the calcium signaling members, plays a critical role in cell tolerance to oxidative stress. We further provide evidence that this channel is required not only for activation of Cap1-related transcription of OSR genes but also for maintaining the stability of both the mitochondria and the vacuole in a potassium- and calcium-dependent manner. Element assays reveal that this TRP channel affects calcium influx and potassium transport from the vacuole to the mitochondria. Therefore, the TRP channel governs the novel interaction among the OSR, the vacuole, and the mitochondria by mediating ion transport in this pathogen under oxidative stress.

Symbiont-derived β-1,3-glucanases in a social insect: mutualism beyond nutrition

Termites have had a long co-evolutionary history with prokaryotic and eukaryotic gut microbes. Historically, the role of these anaerobic obligate symbionts has been attributed to the nutritional welfare of the host. We provide evidence that protozoa (and/or their associated bacteria) colonizing the hindgut of the dampwood termite Zootermopsis angusticollis, synthesize multiple functional β-1,3-glucanases, enzymes known for breaking down β-1,3-glucans, the main component of fungal cell walls. These enzymes, we propose, may help in both digestion of ingested fungal hyphae and protection against invasion by fungal pathogens. This research points to an additional novel role for the mutualistic hindgut microbial consortia of termites, an association that may extend beyond lignocellulolytic activity and nitrogen fixation to include a reduction in the risks of mycosis at both the individual- and colony-levels while nesting in and feeding on microbial-rich decayed wood.

Possible mechanisms of action of mushroom-derived glucans on inflammatory bowel disease and associated cancer

Since ancient times, medicinal mushrooms have been traditionally used as a health food or supplement for the prevention and cure of a range of health-statuses or diseases, such as overt inflammation, atherosclerosis, cancer, hypertension, diabetes and others. We concentrate in this review on the effect and putative mechanism of action of glucans harvested from fungi on inflammatory bowel disease (IBD) and colitis associated cancer. Many scientists including our own group have examined the immunomodulating effect of isolated polysaccharides-glucans in general and specifically in inflammation associated with cancer. In this manuscript we reviewed the sources, the chemical composition and medicinal properties of polysaccharides extracted from edible mushrooms. In addition we brought insights into their putative mechanisms of action behind each health-promoting activity of these interesting biomolecules. The preventive and therapeutic effects of the medicinal mushrooms and their components have been well documented in mouse and rat model systems and in cancer cell lines being the most striking effects reported to their anti-inflammatory and antitumor effect. Their anticancer effects were demonstrated mainly in in vitro and in vivo experimental systems but a very limited number of studies have been conducted in human populations. We can summarize that oral consumption of several mushrooms glucans is an efficient treatment to prevent colitis-associated dysplasias through modulation of mucosal inflammation and cell proliferation. Identifying new food-derived isolates and understanding their mechanisms of action are the main challenges in using mushrooms glucans for therapeutic purposes in the field of IBD and associated cancer. Only an in-depth understanding of the mechanism of action and cross-talk between the inflammatory cell, epithelial cell and fungi derived glucans on which we have a based structural knowledge will lead to well designed intervention clinical human studies to test the efficacy of these molecules on intestinal inflammation and colitis associated cancer.

Anti-inflammatory properties of the medicinal mushroom Cordyceps militaris might be related to its linear (1→3)-β-D-glucan

The Ascomycete Cordyceps militaris, an entomopathogenic fungus, is one of the most important traditional Chinese medicines. Studies related to its pharmacological properties suggest that this mushroom can exert interesting biological activities. Aqueous (CW and HW) and alkaline (K5) extracts containing polysaccharides were prepared from this mushroom, and a β-D-glucan was purified. This polymer was analysed by GC-MS and NMR spectrometry, showing a linear chain composed of β-D-Glcp (1→3)-linked. The six main signals in the 13C-NMR spectrum were assigned by comparison to reported data. The aqueous (CW, HW) extracts stimulated the expression of IL-1β, TNF-α, and COX-2 by THP-1 macrophages, while the alkaline (K5) extract did not show any effect. However, when the extracts were added to the cells in the presence of LPS, K5 showed the highest inhibition of the pro-inflammatory genes expression. This inhibitory effect was also observed for the purified β-(1→3)-D-glucan, that seems to be the most potent anti-inflammatory compound present in the polysaccharide extracts of C. militaris. In vivo, β-(1→3)-D-glucan also inhibited significantly the inflammatory phase of formalin-induced nociceptive response, and, in addition, it reduced the migration of total leukocytes but not the neutrophils induced by LPS. In conclusion, this study clearly demonstrates the anti-inflammatory effect of β-(1→3)-D-glucan.

Seamustard (Undaria pinnatifida) Improves Growth, Immunity, Fatty Acid Profile and Reduces Cholesterol in Hanwoo Steers

The study was designed to evaluate the effect of 2% seamustard (Undaria pinnatifida) by-product (SW) on growth performance, immunity, carcass characteristics, cholesterol content and fatty acid profile in Hanwoo steers. A total of 20 Hanwoo steers (ave. 22 months old; 619 kg body weight) were randomly assigned to control (basal diet) and 2% SW supplemented diet. Dietary SW supplementation significantly (p<0.05) improved average daily gain and gain:feed ratio as well as serum immunoglobulin G concentration. Chemical composition and quality grade of meat and carcass yield grades evaluated at the end of the trial were found to be unaffected by SW supplementation. Dietary SW significantly reduced meat cholesterol concentration (p<0.05). Dietary SW supplementation significantly reduced the myristic acid (C14:0) and palmitoleic acid (C16:ln-7) concentration, while SW increased the concentration of stearic acid (C18:0) and linolenic acid (C18:3n-3) compared to control (p<0.05). Dietary SW supplementation had no effect on saturated fatty acids (SFA), unsaturated fatty acids, poly unsaturated fatty acid (PUFA) or mono unsaturated fatty acid content in muscles. A reduced ratio of PUFA/SFA and n-6/n-3 were found in SW supplemented group (p<0.05). In conclusion, 2% SW supplementation was found to improve growth, immunity and fatty acid profile with significantly reduced cholesterol of beef.

Bacterial β-(1,3)-glucan prevents DSS-induced IBD by restoring the reduced population of regulatory T cells

Bacterial β-(1,3)-glucan has more advantages in terms of cost, yield and efficiency than that derived from mushrooms, plants, yeasts and fungi. We have previously developed a novel and high-yield β-(1,3)-glucan produced by Agrobacterium sp. R259. This study aimed to elucidate the functional mechanism and therapeutic efficacy of bacterial β-(1,3)-glucan in dextran sulfate sodium (DSS)-induced inflammatory bowel disease (IBD).Mice were orally pretreated with bacterial β-(1,3)-glucan at daily doses of 2.5 or 5mg/kg for 2 weeks. After 6 days of DSS treatment, clinical assessment of IBD severity and expression of pro-inflammatory cytokines were evaluated. In vivo cell proliferation was examined by immunohistochemistry using Ki-67 and ER-TR7 antibodies. The frequency of regulatory T cells (Tregs) was analyzed by flow cytometry. Natural killer (NK) activity and IgA level were evaluated using NK cytotoxicity assay and ELISA.The deterioration of body weight gain, colonic architecture, disease score and histological score was recovered in DSS-induced IBD mice when pretreated with bacterial β-(1,3)-glucan. The recruitment of macrophages and the gene expression of proinflammatory cytokines, such as IL-1β, IL-6 and IL-17A/F, were markedly decreased in the colon of β-(1,3)-glucan-pretreated mice. β-(1,3)-Glucan induced the recovery of Tregs in terms of their frequency in DSS-induced IBD mice. Intriguingly, β-(1,3)-glucan reversed the functional defects of NK cells and excessive IgA production in DSS-induced IBD mice.We conclude that bacterial β-(1,3)-glucan prevented the progression of DSS-induced IBD by recovering the reduction of Tregs, functional defect of NK cells and excessive IgA production.

Exopolysaccharide from Ganoderma applanatum as a promising bioactive compound with cytostatic and antibacterial properties

A new exopolysaccharide preparation isolated from stationary cultures of the white rot fungus Ganoderma applanatum (GpEPS) was tested in terms of its bioactive properties including its cytotoxic and immunostimulatory effect. The results indicate that the tested GpEPS (at concentrations above 22.85 µg/mL and 228.5 µg/mL) may exhibit selective activity against tumor cells (cell lines SiHa) and stimulate production of TNF-α THP-1-derived macrophages at the level of 752.17 pg/mL. The GpEPS showed antibacterial properties against Staphyloccoccus aureus and a toxic effect against Vibrio fischeri cells (82.8% cell damage). High cholesterol-binding capacity and triglycerides-binding capacity (57.9% and 41.6% after 24 h of incubation with the tested substances, resp.) were also detected for the investigated samples of GpEPS.

Effect of seaweed-derived laminarin and fucoidan and zinc oxide on gut morphology, nutrient transporters, nutrient digestibility, growth performance and selected microbial populations in weaned pigs

In the present study, two experiments were conducted to (1) evaluate the effect of laminarin and/or fucoidan on ileal morphology, nutrient transporter gene expression and coefficient of total tract apparent digestibility (CTTAD) of nutrients and (2) determine whether laminarin inclusion could be used as an alternative to ZnO supplementation in weaned pig diets. Expt 1 was designed as a 2 × 2 factorial arrangement, comprising four dietary treatments (n 7 replicates, weaning age 24 d, live weight 6·9 kg). The dietary treatments were as follows: (1) basal diet; (2) basal diet+300 ppm laminarin; (3) basal diet+240 ppm fucoidan; (4) basal diet+300 ppm laminarin and 240 ppm fucoidan. There was an interaction between laminarin and fucoidan on the CTTAD of gross energy (GE) (P< 0·05) and the expression of sodium-glucose-linked transporter 1 (SGLT1/SLC5A1) and GLUT1/SLC2A1 and GLUT2/SLC2A2 (P< 0·05) in the ileum. The laminarin diet increased the CTTAD of GE and increased the expression of SGLT1, GLUT1 and GLUT2 compared with the basal diet. However, there was no effect of laminarin supplementation on these variables when combined with fucoidan. Expt 2 was designed as a complete randomised design (n 8 replicates/treatment, weaning age 24 d, live weight 7·0 kg), and the treatments were (1) basal diet, (2) basal diet and laminarin (300 ppm), and (3) basal diet and ZnO (3100 ppm, 0-14 d, and 2600 ppm, 15-32 d post-weaning). The laminarin diet increased average daily gain and gain:feed ratio compared with the basal diet during days 0-32 post-weaning (P< 0·01) and had an effect similar to the ZnO diet. These results demonstrate that laminarin provides a dietary means to improve gut health and growth performance post-weaning.

Immune-modulatory effects of dietary Yeast Beta-1,3/1,6-D-glucan

Beta-glucans are a heterogeneous group of natural polysaccharides mostly investigated for their immunological effects. Due to the low systemic availability of oral preparations, it has been thought that only parenterally applied beta-glucans can modulate the immune system. However, several in vivo and in vitro investigations have revealed that orally applied beta-glucans also exert such effects. Various receptor interactions, explaining possible mode of actions, have been detected. The effects mainly depend on the source and structure of the beta-glucans. In the meantime, several human clinical trials with dietary insoluble yeast beta-glucans have been performed. The results confirm the previous findings of in vivo studies. The results of all studies taken together clearly indicate that oral intake of insoluble yeast beta-glucans is safe and has an immune strengthening effect.

Concentration variation and molecular characteristics of soluble (1,3;1,6)-β-D-glucans in submerged cultivation products of Ganoderma lucidum mycelium

(1,3)-β-D-Glucans with (1,6)-β-D-glucosyl branches are bioactive polysaccharides in fruiting bodies and mycelia of Ganoderma lucidum, a mushroom used in traditional Chinese medicine. Submerged cultivation of mycelium is one of the more efficient means of generating polysaccharides from this fungus. Twelve mycelium samples examined in this study demonstrated the quantitative and qualitative molecular characteristics of soluble (1,3;1,6)-β-D-glucans. It was observed that the concentration of soluble (1,3;1,6)-β-D-glucan varied substantially from 1.3 to 79.9 mg/dL. (1,3;1,6)-β-D-Glucans also preserved their molecular characteristics with degrees of branching (DB) of 0.21-0.36 and molecular masses of 10(5)-10(6) g/mol for those samples with substantial quantities of β-D-glucan. Using the high aggregating tendency of these molecules, (1,3;1,6)-β-D-glucans were successfully purified via fractional precipitation with 35% (v/v) ethanol. (1,3;1,6)-β-D-Glucan was proposed as a putative bioactive marker for immunomodulation because it was the most abundant polysaccharide in G. lucidum mycelium products to stimulate macrophage RAW 264.7 cells to release TNF-α.

β-Glucan supplementation, allergy symptoms, and quality of life in self-described ragweed allergy sufferers

This randomized, placebo-controlled, double-blind study compared the effects of daily supplementation for 4 week with 250 mg Wellmune WGP® β-1,3/1,6-Glucan (WGP) with placebo 250 mg/day (rice flour) on physical and psychological health attributes of self-described “moderate” ragweed allergy sufferers. Study participants (mean age = 36 ± 9 year; range 18–53 year) were recruited before the beginning of ragweed season (September) in Northeastern Ohio. Serum IgE concentration, allergy symptoms [via self-report, Visual Analog Scale (VAS), and Rhinoconjunctivitis Quality of Life Questionnaire (RQLQ)], psychological well-being [Profile of Mood States (POMS)], and physical function (RAND SF-36 Medical Outcomes Study) were measured immediately prior to and after supplementation with WGP (n = 24) or placebo (n = 24) for 4 weeks. Data were analyzed using repeated measures analyses of variance (ANOVA). Compared with placebo, WGP reduced total allergy symptoms (28%), symptom severity (52%), and symptom rating on the VAS (37%) (P < 0.05), but had no effect on serum IgE levels. As measured by the POMS, WGP increased participants' rating of vigor (10%), but reduced tension (34%), depression (45%), anger (41%), fatigue (38%), and confusion (34%) (P < 0.05). Study participants given WGP reported increased physical health (11%), energy (19%), and emotional well-being (7%) compared with study participants given the placebo (RAND SF-36 Medical Outcomes Study). The WGP group also reported decreased sleep problems (53%), reduced nasal symptoms (59%), eye symptoms (57%), non-nasal symptoms (50%), activities (53%), emotions (57%), and improved quality of life (QOL) (56%), as well as improved global mood state (13%). Supplementation with WGP for 4 weeks improved allergy symptoms, overall physical health, and emotional well-being compared with placebo in self-described “moderate” ragweed allergy sufferers during ragweed allergy season.

Novel structural features in Candida albicans hyphal glucan provide a basis for differential innate immune recognition of hyphae versus yeast

The innate immune system differentially recognizes Candida albicans yeast and hyphae. It is not clear how the innate immune system effectively discriminates between yeast and hyphal forms of C. albicans. Glucans are major components of the fungal cell wall and key fungal pathogen-associated molecular patterns. C. albicans yeast glucan has been characterized; however, little is known about glucan structure in C. albicans hyphae. Using an extraction procedure that minimizes degradation of the native structure, we extracted glucans from C. albicans hyphal cell walls. (1)H NMR data analysis revealed that, when compared with reference (1→3,1→6) β-linked glucans and C. albicans yeast glucan, hyphal glucan has a unique cyclical or "closed chain" structure that is not found in yeast glucan. GC/MS analyses showed a high abundance of 3- and 6-linked glucose units when compared with yeast β-glucan. In addition to the expected (1→3), (1→6), and 3,6 linkages, we also identified a 2,3 linkage that has not been reported previously in C. albicans. Hyphal glucan induced robust immune responses in human peripheral blood mononuclear cells and macrophages via a Dectin-1-dependent mechanism. In contrast, C. albicans yeast glucan was a much less potent stimulus. We also demonstrated the capacity of C. albicans hyphal glucan, but not yeast glucan, to induce IL-1β processing and secretion. This finding provides important evidence for understanding the immune discrimination between colonization and invasion at the mucosal level. When taken together, these data provide a structural basis for differential innate immune recognition of C. albicans yeast versus hyphae.

Utility of (1-3)-β-D-glucan testing for diagnostics and monitoring response to treatment during the multistate outbreak of fungal meningitis and other infections

BACKGROUND

 The 2012 outbreak of fungal meningitis associated with contaminated methylprednisolone produced by a compounding pharmacy has resulted in >750 infections. An important question facing patients and clinicians is the duration of antifungal therapy. We evaluated (1-3)-β-d-glucan (BDG) as a marker for monitoring response to treatment.

METHODS

 We determined sensitivity and specificity of BDG testing using the Fungitell assay, by testing 41 cerebrospinal fluid (CSF) specimens from confirmed cases of fungal meningitis and 66 negative control CSF specimens. We also assessed whether BDG levels correlate with clinical status by using incident samples from 108 case patients with meningitis and 20 patients with serially collected CSF.

RESULTS

 A cutoff value of 138 pg/mL provided 100% sensitivity and 98% specificity for diagnosis of fungal meningitis in this outbreak. Patients with serially collected CSF were divided into 2 groups: those in whom BDG levels declined with treatment and those in whom BDG remained elevated. Whereas most patients with a decline in CSF BDG had clinical improvement, all 3 patients with continually elevated BDG had poor clinical outcomes (stroke, meningitis relapse, or development of new disease).

CONCLUSIONS

 Our data suggest that measuring BDG in CSF is a highly sensitive test for diagnosis of fungal meningitis in this outbreak. Analysis of BDG levels in serially collected CSF demonstrated that BDG may correlate with clinical response. Routine measurement of BDG in CSF may provide useful adjunctive data for the clinical management of patients with outbreak-associated meningitis.

Effect of dietary laminarin and fucoidan on selected microbiota, intestinal morphology and immune status of the newly weaned pig

A 2 × 2 factorial experiment was conducted to investigate the interactions between laminarin (LAM; 0 and 300 parts per million (ppm)) and fucoidan (FUC; 0 and 240 ppm) levels on intestinal morphology, selected microbiota and inflammatory cytokine gene expression in the weaned pig. There was an interaction between LAM and FUC supplementation on the Enterobacteriaceae population (P< 0·05) and the abundance of attaching and effacing Escherichia coli (AEEC) strains (P< 0·05) in the colon. Pigs offered the FUC diet had a reduced Enterobacteriaceae population compared with pigs offered the basal diet. However, the effect of FUC on the Enterobacteriaceae population was not observed when combined with LAM. Pigs offered the LAM diet had reduced abundance of AEEC strains compared with pigs offered the basal diet. However, there was no effect of LAM on the abundance of AEEC strains when combined with FUC. There was an interaction between LAM and FUC supplementation on villous height (P< 0·01) and the villous height:crypt depth ratio (P< 0·01) in the duodenum. Pigs offered the LAM or FUC diet had an increased villous height and villous height:crypt depth ratio compared with pigs offered the basal diet. However, there was no effect of the LAM and FUC combination diet on intestinal morphology. Pigs offered the LAM-supplemented diets had a lower IL-6 (P< 0·05), IL-17A (P< 0·01) and IL-1β (P< 0·01) mRNA expression in the colon compared with pigs offered the diets without LAM. In conclusion, supplementation with either LAM or FUC alone modified intestinal morphology and selected intestinal microbiota, but these effects were lost when offered in combination.

Immunostimulatory activities of β-d-glucan from Ganoderma Lucidum

A water-insoluble β-(1 → 3)-D-glucan (GLPs) with few branches at C-6 and C-2 positions was extracted from the fruit body of Ganoderma Lucidum by 1M NaOH at 40 °C. By the striking inhibition of NO and TNF-α production, GLPs showed significant anti-inflammation activity against LPS induced Raw 264.7 cells. Results of RT-PCR revealed the down regulation of iNOS and TNF-α mRNA gene expression. GLPs severely inhibited the phosphorylation of IκBα and JNK1/2, while the ERK1/2 and p38 were not apparently affected by GLPs. The neutralizing antibodies against dectin-1 and TLR-4, respectively, did not affect GLPs-mediated inhibition of NO production. But neutralizing of TLR2 affected the inhibition of NO. All of these results revealed that GLPs can inhibit the inflammation of Raw 264.7 cell induced by LPS at least partially attributed to the blocking of NF-κB and JNK MAPK, and TLR2 plays a major role in GLPs anti-inflammation activity.

Characterization of a β-1,3-glucan recognition protein from the beet armyworm, Spodoptera exigua (Insecta: Lepidoptera: Noctuidae)

The β-1,3-glucan recognition protein gene from Spodoptera exigua (SeβGRP) was cloned and characterized. The cDNA of this gene is 1 644 nucleotides in length and the predicted polypeptide is 491 amino acids (aa) in length, with a calculated molecular mass of 54.8 kDa. The first 22 aa encode a predicted secretion signal peptide. A BLAST search, multiple sequence alignment, and phylogenetic analysis of the aa sequence of SeβGRP revealed that this protein is most similar to the β-1,3-glucan recognition protein (βGRP) family of pattern recognition proteins. Using reverse-transcription polymerase chain reaction, we detected the presence of SeβGRP transcripts in the egg, larval, pupal, and adult stages of S. exigua. In addition, the SeβGRP transcript was expressed in all the tissues examined including the brain, hemocytes, fat body, intestine, and cuticle. There were no changes in SeβGRP mRNA levels in larvae infected with ultraviolet (UV)-killed Escherichia coli DH5α compared with the control larvae inoculated with the water; however, SeβGRP mRNA levels were markedly elevated 4-8 h after infection and slightly induced 12-24 h after infection in larvae injected with UV-killed Fusarium oxysporum. This may be because β-1,3-glucan is the main component of the cell wall of F. oxysporum, but not E. coli DH5α.

Beta-glucan feeding effect on biochemical and immune responses in vaccinated and non-vaccinated piglets against proliferative enteropathy

The aim of this study was to compare the results of active non-specific immuno-modulation in form of feeding food additive based on beta-glucan to pregnant sows and consecutive specific immuno-modulation by vaccination of their sucklings. Experimental sows were fed feedstuff with preparation on basis of beta-glucan at a 5% concentration from day 14 before parturition until the weaning of piglets; control sows were fed standard feedstuff only. Sucklings were vaccinated with a single dose of 2 ml of oral vaccine Enterisol® Ileitis one week before weaning. Collection of biological material was done 3 × in sows and 5 × in sucklings. Post-vaccination examination of blood serum for antibodies against L. intracellularis in sucklings in experimental and control groups was negative, probably due to insufficiently long period of rejection of antibiotics-medicated feedstuff and by chlorinated water. With the exception of immunological profile, no essential changes were recorded in the dynamics of other indices of examined profiles in groups of sows in relation to immune-modulation. In groups of sucklings from sows fed beta-glucan supplemented feedstuff significant changes were determined for various indices compared with sucklings from sows fed standard foodstuff. This is the first similar study in pig herds in Slovakia.

Analysis of bacterial community shifts in the gastrointestinal tract of pigs fed diets supplemented with β-glucan from Laminaria digitata, Laminaria hyperborea and Saccharomyces cerevisiae

This study was designed to evaluate the effects of algal and yeast β-glucans on the porcine gastrointestinal microbiota, specifically the community of Lactobacillus, Bifidobacterium and coliforms. A total of 48 pigs were fed four diets over a 28-day period to determine the effect that each had on these communities. The control diet consisted of wheat and soya bean meal. The remaining three diets contained wheat and soya bean meal supplemented with β-glucan at 250 g/tonne from Laminaria digitata, Laminaria hyperborea or Saccharomyces cerevisiae. Faecal samples were collected from animals before feeding each diet and after the feeding period. The animals were slaughtered the following day and samples were collected from the stomach, ileum, caecum, proximal colon and distal colon. Alterations in Lactobacillus in the gastrointestinal tract (GIT) were analysed using denaturing gradient gel electrophoresis (DGGE) profiles generated by group-specific 16S rRNA gene PCR amplicons. Plate count analysis was also performed to quantify total coliforms. DGGE profiles indicated that all β-glucan diets provoked the emergence of a richer community of Lactobacillus. The richest community of lactobacilli emerged after feeding L. digitata (LD β-glucan). Plate count analysis revealed that the L. hyperborea (LH β-glucan) diet had a statistically significant effect on the coliform counts in the proximal colon in comparison with the control diet. β-glucan from L. digitata and S. cerevisiae also generally reduced coliforms but to a lesser extent. Nevertheless, the β-glucan diets did not significantly reduce levels of Lactobacillus or Bifidobacterium. DGGE analysis of GIT samples indicated that the three β-glucan diets generally promoted the establishment of a more varied range of Lactobacillus species in the caecum, proximal and distal colon. The LH β-glucan had the most profound reducing effect on coliform counts when compared with the control diet and diets supplemented with L. digitata and S. cerevisiae β-glucans.

The effects of liquid versus spray-dried Laminaria digitata extract on selected bacterial groups in the piglet gastrointestinal tract (GIT) microbiota

In this study, the effects of supplementing animal feed with a liquid and spray-dried fucoidan and laminarin extract, derived from the seaweed Laminaria digitata on the porcine gastrointestinal microbiota, specifically the communities of Lactobacillus, Bifidobacterium and enterobacteria were evaluated. Twenty four piglets were fed one of three diets over a 21-day period to determine the effect that each had on the bacterial communities. The dietary treatments were as follows; (1) control diet, (2) control diet plus spray-dried formulation of laminarin fucoidan (L/F-SD) extract, (3) control diet plus a liquid formulation of (L/F-WS) extract. Control diet consisted of wheat, soya bean meal, soya oil and a vitamin and mineral mixture. The L/F-SD and L/F-WS supplemented diets had equal proportion of 500 ppm laminarin and fucoidan. At the end of the 21 day feeding period all animals were sacrificed and samples were collected from the ileum, caecum and colon. Counts were determined for Lactobacillus, Bifidobacterium and enterobacteria. Plate count analysis revealed that the L/F-SD diet caused a statistically significant 1.5 log and 2 log increases in the Lactobacillus and Bifidobacterium counts of ileum samples respectively. A greater difference was observed with the L/F-WS diet in that Lactobacillus and Bifidobacterium increased by 2 log and 3 log respectively. Alterations in the Lactobacillus species composition of the gastrointestinal tract (GIT) were analysed using specific PCR - denaturing gradient gel electrophoresis (PCR-DGGE). The DGGE profiles indicated that Lactobacillus species richness decreased along the gastrointestinal tract i.e. the number of dominant species detected in the colon was less than those detected in the ileum and caecum irrespective of the diet consumed. Consumption of both the L/F-SD and L/F-WS diets resulted in a richer Lactobacillus species composition in the ileum, with the L/F-SD diet being associated the emergence of Lactobacillus agilis in the colon. The study indicated that the L/F-WS extract was superior to the L/F-SD extract in increasing the titre of beneficial bacteria in the gastrointestinal tract (GIT).

The physicochemical properties of a new class of anticancer fungal polysaccharides: a comparative study

The structural and physicochemical properties of polysaccharides isolated from fungi with anticancer properties were investigated. The majority of the polysaccharides considered, have the β-d-Glcp component mostly connected by 1→3 and 1→6 linkages in the backbones and the short branches, respectively. The established parameters of lead-like, drug-like and of known dug space (KDS) were used and the repeating units of the polysaccharides exhibit some overlap with these. It was found that a unique region of chemical space is occupied by the polysaccharides, with MW: 1.0 x 10(5) to 2.5 x 10(5) g mol(-1); LogP: -3.0 x 10(3) to -1.0 x 10(3); HD: 1.0 x 10(3) to 5.0 x 10(3); HA: 5.0 x 10(3) to 1.0 x 10(4); PSA: 5.0 x 10(4) to 1.0 x 10(5) and RB: 5.0 x 10(3) to 1.0 x 10(4). These findings can be exploited in antitumor drug discovery projects.

Genetic basis for recurrent vulvo-vaginal candidiasis

Vulvovaginal candidiasis (VVC) is a frequent disease affecting more than 75% of all women at least once in their lifetime. Up to 8% of them suffer from recurrent VVC (RVVC) characterized by at least three episodes each year. Several risk factors, such as antibiotic use, diabetes, or pregnancy, are known, but the vast majority of women with RVVC develop the infection without having any risk factor, implying that a genetic component most likely plays an important role in the susceptibility to RVVC. This review summarizes the immunogenetic alterations that lead to an increased susceptibility to vaginal infections with Candida albicans. Different mutations and polymorphisms in innate immune genes alter the mucosal immune response against fungi and are likely to have an important role in susceptibility to RVVC. A better understanding of the genetic and immunological mechanisms leading to RVVC is important for both the understanding of the pathophysiology of the disease and the design of novel therapeutic strategies.

Mannosyl-recognizing receptors induce an M1-like phenotype in macrophages of susceptible mice but an M2-like phenotype in mice resistant to a fungal infection

In addition to alpha1,3 glucan, mannan and mannan-linked proteins are expressed in the outer layer of Paracoccidioides brasiliensis yeasts. The recognition of mannosyl residues by multiple pathogen recognition receptors, such as the mannose receptor (MR), complement receptor 3 (CR3) and toll-like receptor 4 (TLR4) on macrophage membranes can influence macrophage activation and the mechanisms of innate immunity against fungal pathogens. The aim of this study was to clarify the role of these receptors in the interaction between P. brasiliensis and macrophages from resistant (A/J) and susceptible (B10.A) mice. Therefore, the phagocytic, fungicidal and secretory abilities of macrophages were evaluated in the presence of mannan and antibodies against MR, CR3 and TLR4. We verified that mannan increased and anti-MR antibody decreased the killing ability and nitric oxide production of macrophages. The specific blockade of MR, CR3 and TLR4 by monoclonal antibodies impaired fungal recognition and modulated the production of cytokines. Mannan or P. brasiliensis induced decreased expression of MR and TLR2 on A/J macrophages, whereas CR3, TLR4 and TLR2 were reduced on B10.A cells. Importantly, both mannan and P. brasiliensis induced the production of IL-12 by B10.A macrophages, whereas TGF-β, TNF-α and IL-6 were produced by A/J cells. In addition, B10.A macrophages exhibited a prevalent expression of inducible NO-synthase and SOCS3 (suppressor of cytokine signaling-3), indicating a pro-inflammatory, "M1-like" differentiation. In contrast, the elevated expression of arginase-1, found in inflammatory zone-1 (FIZZ1), YM1 (CHI313, chitinase-like lectin), and SOCS1, typical markers of alternatively activated macrophages, indicates a prevalent "M2-like" differentiation of A/J macrophages. In conclusion, our data reveal that several mannosyl-recognizing receptors coordinate the apparently paradoxical innate response to paracoccidioidomycosis, in which resistance is initially mediated by alternatively activated phagocytes and tolerance to fungal growth, whereas susceptibility is linked to classically activated macrophages and the efficient control of fungal growth.

Serum (1→3)-β-D-glucan levels in HIV-infected individuals are associated with immunosuppression, inflammation, and cardiopulmonary function

BACKGROUND

Translocation of gastrointestinal bacteria in HIV-infected individuals is associated with systemic inflammation, HIV progression, mortality, and comorbidities. HIV-infected individuals are also susceptible to fungal infection and colonization, but whether fungal translocation occurs and influences HIV progression or comorbidities is unknown.

METHODS

Serum (1→3)-β-D-glucan (BG) was measured by a Limulus Amebocyte Lysate assay (Fungitell) in 132 HIV-infected outpatients. Selected plasma cytokines and markers of peripheral T-cell activation were measured. Pulmonary function testing and Doppler echocardiography were performed. Relationship of high (≥40 pg/mL) and low (<40 pg/mL) levels of BG with HIV-associated variables, inflammation markers, and pulmonary function and pulmonary hypertension measures were determined.

RESULTS

Forty-eight percent of patients had detectable BG, and 16.7% had high levels. Individuals with high BG were more likely to have CD4 counts less than 200 cells/μL (31.8% vs. 8.4%, P = 0.002), had higher log10 HIV viral levels (2.85 vs. 2.13 log copies/mL, P = 0.004), and were less likely to use antiretroviral therapy (68.2% vs. 90.0%, P = 0.006). Plasma IL-8 (P = 0.033), TNF-α (P = 0.029), and CD8CD38 (P = 0.046) and CD8HLA-DR (P = 0.029) were also increased with high levels. Abnormalities in diffusing capacity (P = 0.041) and in pulmonary artery pressures (P = 0.006 for pulmonary artery systolic pressure and 0.013 for tricuspid regurgitant velocity) were more common in those with high BG.

CONCLUSIONS

We found evidence of peripheral fungal cell wall polysaccharides in an HIV-infected cohort. We also demonstrated an association between high serum BG, HIV-associated immunosuppression, inflammation, and cardiopulmonary comorbidity. These results implicate a new class of pathogen in HIV-associated microbial translocation and suggest a role in HIV progression and comorbidities.

Immunomodulatory effect of pleuran (β-glucan from Pleurotus ostreatus) in children with recurrent respiratory tract infections

OBJECTIVES

Recurrent respiratory tract infections (RRTIs) represent a very important problem in daily clinical practice because of their significant contribution to morbidity in children. Several natural nutritional supplements have been used in the prevention of RRTIs, but the clinical efficacy of only a few preparations is supported by scientific evidence.

MATERIALS AND METHODS

In a double-blind, placebo-controlled, randomised, multicentre study, we have observed a group of 175 children (aged 5.65 ± 2.39 years) with more than 5 respiratory infections that occurred during the 12 months prior to the beginning of the study. Children were randomised into an active group, treated with Imunoglukan P4H® syrup (with pleuran-β-glucan from Pleurotus ostreatus and vitamin C), or a placebo group (vitamin C only). During the 3 visits, within a 12-month period, questionnaires were completed, and blood samples were examined for immune parameters.

RESULTS

In the active group, 36% of the children did not suffer from any respiratory infections throughout the treatment, compared to 21% in the placebo group (p<0.05). Imunoglukan P4H® also significantly decreased the frequency of flu and flu-like disease and the number of lower respiratory tract infections. Imunoglukan P4H® treatment resulted in a statistically significant modulation of humoral and cellular immunity.

CONCLUSIONS

Results from this study demonstrate that Imunoglukan P4H® is effective in the prevention of RRTIs in children. Furthermore, our results also revealed complex immunomodulatory activity of this product. This is the first double-blind, placebo-controlled study in children with RRTIs that has addressed the preventive effects of pleuran on morbidity caused by respiratory infections.

Brucella β 1,2 cyclic glucan is an activator of human and mouse dendritic cells

Bacterial cyclic glucans are glucose polymers that concentrate within the periplasm of alpha-proteobacteria. These molecules are necessary to maintain the homeostasis of the cell envelope by contributing to the osmolarity of Gram negative bacteria. Here, we demonstrate that Brucella β 1,2 cyclic glucans are potent activators of human and mouse dendritic cells. Dendritic cells activation by Brucella β 1,2 cyclic glucans requires TLR4, MyD88 and TRIF, but not CD14. The Brucella cyclic glucans showed neither toxicity nor immunogenicity compared to LPS and triggered antigen-specific CD8⁺ T cell responses in vivo. These cyclic glucans also enhanced antigen-specific CD4⁺ and CD8⁺ T cell responses including cross-presentation by different human DC subsets. Brucella β 1,2 cyclic glucans increased the memory CD4⁺ T cell responses of blood mononuclear cells exposed to recombinant fusion proteins composed of anti-CD40 antibody and antigens from both hepatitis C virus and Mycobacterium tuberculosis. Thus cyclic glucans represent a new class of adjuvants, which might contribute to the development of effective antimicrobial therapies.

Vaccination is one of the key strategies to fight against infectious diseases though numerous diseases remain without appropriate vaccines. The challenge is to generate potent vaccines capable of inducing long-lasting immunity in humans. Successful vaccines include adjuvants that enhance and appropriately skew the immune response to given antigens. The development of new adjuvants for human vaccines has become an expanding field of research. Here we show that bacterial cyclic β-glucans can be used to enhance cellular immunity by activation of dendritic cells, from both mice and humans. In particular, Cyclic-β glucans enhance the in vitro memory CD4+ T cell responses of patients suffering from hepatitis C and tuberculosis. Thus cyclic-β glucans are new adjuvants, which might be used in vaccines.

The effects of seaweed extract inclusion on gut morphology, selected intestinal microbiota, nutrient digestibility, volatile fatty acid concentrations and the immune status of the weaned pig

An experiment (complete randomised design) was conducted to investigate the effects of Laminaria hyperborea and Laminaria digitata seaweed extract inclusion on gut morphology, selected intestinal microbiota populations, volatile fatty acid concentrations and the immune status of the weaned pig. Twenty-eight piglets (24 days of age, 6.5 ± 1.4 kg live weight) were assigned to one of four dietary treatments for 7 days and then sacrificed: (T1) basal diet (control); (T2) basal diet and 1.5 g/kg L. hyperborea seaweed extract; (T3) basal diet and 1.5 g/kg L. digitata seaweed extract; and (T4) basal diet and 1.5 g/kg of a combination of L. hyperborea and L. digitata seaweed extract. The seaweed extract contained both laminarin and fucoidan. Digesta samples were taken from the caecum and colon to measure the enterobacteria, bifidobacteria and lactobacilli populations and for volatile fatty acid analysis. Tissue samples were taken from the duodenum, jejunum and ileum for morphological examination. Blood samples were taken to determine the cytokine gene expression profile and to measure the phagocytotic capacity of the blood. Pigs offered diets containing L. hyperborea seaweed extract had less bifidobacteria in the colon (P < 0.05) and lactobacilli in the caecum (P < 0.05) and colon (P < 0.001). The inclusion of L. digitata seaweed extract resulted in lower populations of enterobacteria in the caecum and colon (P < 0.01), bifidobacteria in the caecum (P < 0.05), and lactobacilli in the caecum (P < 0.05) and colon (P < 0.001). Pigs offered the combination of L. hyperborea and L. digitata seaweed extracts had less enterobacteria (P < 0.05) and lactobacilli (P < 0.01) in the caecum and colon. Pigs offered the L. digitata-supplemented diet had a reduced villous height in the duodenum and jejunum (P < 0.05). The inclusion of the L. digitata seaweed extract increased the molar proportion of butyric acid in the colon (P < 0.05). There was a significant reduction in the ammonia concentration in the colon with the inclusion of L. hyperborea (P < 0.01) and L. digitata (P < 0.05) seaweed extracts. An increase in the expression of the Interleukin-8 mRNA was observed on day 6 with the supplementation of the combination of L. hyperborea and L. digitata seaweed extract (P < 0.05). The inclusion of L. hyperborea seaweed extract resulted in an increase in total monocyte number (P < 0.05). In conclusion, the supplementation of L. hyperborea and L. digitata seaweed extract alone and in combination reduced the enterobacteria, bifidobacteria and lactobacilli populations in the caecum and colon, while only marginal effects on the immune response was observed.

The effect of dietary laminarin and fucoidan in the diet of the weanling piglet on performance, selected faecal microbial populations and volatile fatty acid concentrations

A 2 × 2 factorial experiment (n = 12 replicates per treatment, 4 pigs per replicate) was performed to investigate the effects of seaweed extracts, laminarin (derived ß-glucans) and fucoidan (sulphated polysaccharides), independently or in combination on post-weaning piglet performance and selected microbial populations. At weaning, the piglets (24 days of age, 6.4 kg live weight) were assigned to one of the four dietary treatments: (T1) basal diet, (T2) basal diet with 300 p.p.m. laminarin, (T3) basal diet with 240 p.p.m. fucoidan, (T4) basal diet with 300 p.p.m. laminarin and 240 p.p.m. fucoidan. Pigs offered diets supplemented with laminarin had an increased daily gain (P < 0.01), and gain-to-feed ratio (P < 0.05) compared to pigs offered diets without laminarin supplementation during the experimental period (days 0 to 21). Pigs offered laminarin-supplemented diets had an increased faecal dry matter and reduced diarrhoea (P < 0.05) during the critical 7 to 14 day period. Pigs offered diets containing laminarin had reduced faecal Escherichia coli populations. There was a significant interaction (P < 0.01) on faecal Lactobacilli populations between laminarin and fucoidan. Pigs offered the fucoidan diet had an increased Lactobacilli population compared to pigs offered the basal diet. However, there was no effect of fucoidan on faecal Lactobacilli populations when laminarin was added. Overall, the reduction in E. coli population and the increase in daily gain suggest that laminarin may provide a dietary means to improve gut health after weaning.

Effect of purified β-glucans derived from Laminaria digitata, Laminaria hyperborea and Saccharomyces cerevisiae on piglet performance, selected bacterial populations, volatile fatty acids and pro-inflammatory cytokines in the gastrointestinal tract of pigs

β-Glucans have been identified as natural biomolecules with immunomodulatory activity. The first objective of the present study was to compare the effects of purified β-glucans derived from Laminaria digitata, L. hyperborea and Saccharomyces cerevisiae on piglet performance, selected bacterial populations and intestinal volatile fatty acid (VFA) production. The second aim was to compare the gene expression profiles of the markers of pro- and anti-inflammation in both unchallenged and lipopolysaccharide (LPS)-challenged ileal and colonic tissues. β-Glucans were included at 250 mg/kg in the diets. The β-glucans derived from L. hyperborea, L. digitata and S. cerevisiae all reduced the Enterobacteriaceae population (P<0·05) without influencing the lactobacilli and bifidobacteria populations (P>0·05) in the ileum and colon. There was a significant interaction between gastrointestinal region and β-glucan source in the expression of cytokine markers, IL-1α (<0·001), IL-10 (P<0·05), TNF-α (P<0·05) and IL-17A (P<0·001). β-Glucans did not stimulate any pro- or anti-inflammatory cytokine markers in the ileal epithelial cells. In contrast, the expression of a panel of pro- and anti-inflammatory cytokines (IL-1α, IL-10, TNF-α and IL-17A) was down-regulated in the colon following exposure to β-glucans from all the three sources. However, the data suggest that the soluble β-glucans derived from L. digitata may be acting via a different mechanism from the insoluble β-glucans derived from L. hyperborea and S. cerevisiae, as the VFA profile was different in the L. digitata-treated animals. There was an increase in IL-8 gene expression (P<0·05) in the gastrointestinal tract from the animals exposed to L. digitata following an LPS ex vivo challenge that was not evident in the other two treatment groups. In conclusion, β-glucans from both seaweed and yeast sources reduce Enterobacteriaceae counts and pro-inflammatory markers in the colon, though the mechanisms of action may be different between the soluble and insoluble fibre sources.

Transcriptional regulation of cytokines in the intestine of Atlantic cod fed yeast derived mannan oligosaccharide or β-glucan and challenged with Vibrio anguillarum

Immunomodulatory feed additives are expected to exert their primary influence at the intestinal level through the expression of cytokines, which in turn affect the immune responses in fish. In two separate experiments a yeast-derived mannan oligosaccharide product (YM) or a purified β-glucan (BG) product were fed to Atlantic cod (Gadus morhua L.) for 5 weeks, after which they were bath-challenged with a bacterial pathogen--Vibrio anguillarum. The transcription of selected cytokines (proinflammatory--il1b, il8, ifng; anti-inflammatory--il10) in different intestinal segments was analysed using qPCR. In the case of YM study, the effect of the compound was observed in both the posterior intestine and rectum of Atlantic cod, upon challenge with the pathogen. iIl1b expression in the posterior intestine and rectum of post-challenge fish was significantly higher than that of pre-challenge fish. In the case of il8 the difference was confined to rectum. The expression of ifng was altered only in the anterior intestine upon YM feeding. In the BG trial, the additive had a differential effect on the expression of the cytokine genes. In anterior intestine and rectum, the purified β-glucan additive significantly elevated the expression of il1b when challenged with V. anguillarum. An effect of BG on the anti-inflammatory cytokine il10 was visible in the rectum after the pathogen challenge. The differential responses of cytokines in the intestine of fish upon exposure to V. anguillarum suggest that both mannan oligosaccharides and β-glucans impact the ability of Atlantic cod to respond to the pathogen.

Immunostimulatory Effects of β-glucan Purified from Paenibacillus polymyxa JB115 on Mouse Splenocytes

We investigated the effects of β-glucan purified from Paenibacillus polymyxa JB115 on the viability and proliferation of splenocytes. Splenocytes play a critical role in host immunity. MTT assays and trypan blue exclusion tests revealed that β-glucan significantly promoted the viability and proliferation of splenocytes over a range of concentrations. However, there was no specific subset change. β-glucan protected splenocytes from cytokine withdrawal-induced spontaneous cell death. For further mechanistic studies, ELISA assay revealed that β-glucan enhanced the expression of anti-apoptotic molecules and interleukin 7 (IL-7), a cytokine critical for lymphocyte survival. We also investigated the IL-2 dependency of β-glucan-treated splenocytes to determine if treated cells could still undergo clonal expansion. In flow cytometric analysis, β-glucan induced increased levels of the activation marker CD25 on the surface of splenocytes and β-glucan-treated splenocytes showed higher proliferation rates in response to IL-2 treatment. This study demonstrates that β-glucan can enhance the survival of splenocytes and provides valuable information to broaden the use of β-glucan in research fields.

The modular nature of dendritic cell responses to commensal and pathogenic fungi

The type of adaptive immune response following host-fungi interaction is largely determined at the level of the antigen-presenting cells, and in particular by dendritic cells (DCs). The extent to which transcriptional regulatory events determine the decision making process in DCs is still an open question. By applying the highly structured DC-ATLAS pathways to analyze DC responses, we classified the various stimuli by revealing the modular nature of the different transcriptional programs governing the recognition of either pathogenic or commensal fungi. Through comparison of the network parts affected by DC stimulation with fungal cells and purified single agonists, we could determine the contribution of each receptor during the recognition process. We observed that initial recognition of a fungus creates a temporal window during which the simultaneous recruitment of cell surface receptors can intensify, complement and sustain the DC activation process. The breakdown of the response to whole live cells, through the purified components, showed how the response to invading fungi uses a set of specific modules. We find that at the start of fungal recognition, DCs rapidly initiate the activation process. Ligand recognition is further enhanced by over-expression of the receptor genes, with a significant correspondence between gene expression and protein levels and function. Then a marked decrease in the receptor levels follows, suggesting that at this moment the DC commits to a specific fate. Overall our pathway based studies show that the temporal window of the fungal recognition process depends on the availability of ligands and is different for pathogens and commensals. Modular analysis of receptor and signalling-adaptor expression changes, in the early phase of pathogen recognition, is a valuable tool for rapid and efficient dissection of the pathogen derived components that determine the phenotype of the DC and thereby the type of immune response initiated.