Yeast-derived Β-glucan Research Articles

Orally administered yeast-derived β-glucan alleviates mast cell-dependent airway hyperresponsiveness and inflammation in a murine model of asthma.

Particulate β-glucans (WGP) are natural compounds with regulatory roles in various biological processes, including tumorigenesis and inflammatory diseases such as allergic asthma. However, their impact on mast cells (MCs), contributors to airway hyperresponsiveness (AHR) and inflammation in asthma mice, remains unknown. C57BL/6 mice underwent repeated OVA sensitization without alum, followed by Ovalbumin (OVA) challenge. Mice received daily oral administration of WGP (OAW) at doses of 50 or 150 mg/kg before sensitization and challenge. We assessed airway function, lung histopathology, and pulmonary inflammatory cell composition in the airways, as well as proinflammatory cytokines and chemokines in the bronchoalveolar lavage fluid (BALF). The 150 mg/kg OAW treatment mitigated OVA-induced AHR and airway inflammation, evidenced by reduced airway reactivity to aerosolized methacholine (Mch), diminished inflammatory cell infiltration, and goblet cell hyperplasia in lung tissues. Additionally, OAW hindered the recruitment of inflammatory cells, including MCs and eosinophils, in lung tissues and BALF. OAW treatment attenuated proinflammatory tumor necrosis factor (TNF)-α and IL-6 levels in BALF. Notably, OAW significantly downregulated the expression of chemokines CCL3, CCL5, CCL20, CCL22, CXCL9, and CXCL10 in BALF. These results highlight OAW's robust anti-inflammatory properties, suggesting potential benefits in treating MC-dependent AHR and allergic inflammation by influencing inflammatory cell infiltration and regulating proinflammatory cytokines and chemokines in the airways.

Dietary Intake of Yeast-Derived β-Glucan and Rice-Derived Arabinoxylan Induces Dose-Dependent Innate Immune Priming in Mice.

Beta-glucans and arabinoxylans are known for their immunostimulatory properties. However, in vivo these have been documented almost exclusively following parenteral administration, underemphasizing oral intake. C57BL/6 mice are fed either a control diet or a diet supplemented with yeast-derived whole β-glucan particle (yWGP) or with rice-derived arabinoxylan (rice bran-1) at a concentration of 1%, 2.5%, or 5% weight/weight (w/w)for 2 weeks. Thereafter, cells from blood, bone marrow, and spleen are collected for ex vivo stimulation with various microbial stimuli. Dietary intake of yWGP for 2 weeks at concentrations of 1% and 2.5% w/w increases ex vivo cytokine production in mouse blood and bone marrow, whereas 5% w/w yWGP shows no effect. In the spleen, cytokine production remains unaffected by yWGP. At a concentration of 1% w/w, rice bran-1 increases ex vivo cytokine production by whole blood, but 2.5% and 5% w/w cause inhibitory effects in bone marrow and spleen. This study demonstrates that dietary yWGP and rice bran-1 induce immune priming in mouse blood and bone marrow, with the strongest effects observed at 1% w/w. Future human trials should substantiate the efficacy of dietary β-glucans and arabinoxylans to bolster host immunity, focusing on dose optimization.

β-glucans from Agaricus bisporus mushroom products drive Trained Immunity.

Macrofungi, such as edible mushrooms, have been used as a valuable medical resource for millennia as a result of their antibacterial and immuno-modulatory components. Mushrooms contain dietary fibers known as β-glucans, a class of polysaccharides previously linked to the induction of Trained Immunity. However, little is known about the ability of mushroom-derived β-glucans to induce Trained Immunity. Using various powdered forms of the white button mushroom (Agaricus bisporus), we found that mouse macrophages pre-treated with whole mushroom powder (WMP) displayed enhanced responses to restimulation with TLR ligands, being particularly sensitive to Toll-like receptor (TLR)-2 stimulation using synthetic lipopeptides. This trained response was modest compared to training observed with yeast-derived β-glucans and correlated with the amount of available β-glucans in the WMP. Enriching for β-glucans content using either a simulated in-vitro digestion or chemical fractionation retained and boosted the trained response with WMP, respectively. Importantly, both WMP and digested-WMP preparations retained β-glucans as identified by nuclear magnetic resonance analysis and both displayed the capacity to train human monocytes and enhanced responses to restimulation. To determine if dietary incorporation of mushroom products can lead to Trained Immunity in myeloid cells in vivo, mice were given a regimen of WMP by oral gavage prior to sacrifice. Flow cytometric analysis of bone-marrow progenitors indicated alterations in hematopoietic stem and progenitor cells population dynamics, with shift toward myeloid-committed multi-potent progenitor cells. Mature bone marrow-derived macrophages derived from these mice displayed enhanced responses to restimulation, again particularly sensitive to TLR2. Taken together, these data demonstrate that β-glucans from common macrofungi can train innate immune cells and could point to novel ways of delivering bio-available β-glucans for education of the innate immune system.

The effect of yeast-derived β-glucans in reducing the adverse outcome of Lawsonia intracellularis in finishing pigs

IntroductionChronic diarrhoea is one of the most recurrent health issues in pig herds. Among Q9 the causative agents of diarrhoea, Lawsonia intracellularis is quite frequent with worldwide distribution leading to detrimental economical losses, as a result of the poor growth rate of the infected pigs. A growing body of evidence has shown that branched yeast b-glucans are excellent inducers of innate immunity memory in humans and in pigs.MethodsIn this study, yeast branched b-glucans were evaluated as a potential solution to control infection by L. intracellularis in pigs by reducing the shedding of L. intracellularis in the faeces of infected animals. To address this hypothesis, naturally infected grow finishing pigs were divided into two treatment groups (n=80) and fed either with a basal diet (Control) or the same basal diet supplemented with 250 g/ton b-glucans (BG-fed group).ResultsOur results have shown that BG-supplemented pigs during the growing and finishing period had significantly increased body weight (BW) by 4.22 kg on average on day 97 and ADG up to 5.6% over the whole experiment (p<5.0 x 10-2) with no significant increase in ADFI. Similarly, supplementation of pigs with BG during the grow-finish phase has significantly reduced (p<4.0x10-4) faecal shedding of the bacteria in infected pigs on day 97. Furthermore, our results indicate that microbial a-diversity was negatively correlated with the presence of L. intracellularis. Animals fed with yeast BG show a reduction of the two genera Sarcina and Catenibacterium and a deeper analysis indicated that the ratio of Fibrobacter to Lacnospiraceae_AC2044 group could be a potential marker for L. Intracellularis susceptibility.ConclusionThis study demonstrated the beneficial effect of adding branched yeast BG in the diet of grow-finish pigs in reducing the dissemination of L. intracellularis between pigs in a given herd.

Irreversible electroporation augments β-glucan induced trained innate immunity for the treatment of pancreatic ductal adenocarcinoma

BackgroundPancreatic cancer (PC) is a challenging diagnosis that is yet to benefit from the advancements in immuno-oncologic treatments. Irreversible electroporation (IRE), a non-thermal method of tumor ablation, is used in...

Structural identification of active moiety in anti-tumor metastatic polysaccharide purified from fermented barley by sequential enzymatic hydrolysis

The potent anti-cancer metastatic effects induced by the immunostimulatory activities of intravenously administered BF–I, an active polysaccharide purified from fermented barley, were previously evaluated. This study aimed to evaluate the anti-cancer metastatic effect of orally administered BF–I and elucidated the microstructure and active moiety of BF–I using sequential enzymatic hydrolysis. In experiments using Colon26-M3.1 carcinoma, prophylactic oral administration of BF–I potently suppressed lung cancer metastasis. Furthermore, gas chromatography-mass spectrometry analysis of partially methylated alditol acetate showed that BF–I comprised 15 different glycosyl linkages, including 4-linked Xylp (16.1%), terminal Araf (12.4%), 4-linked Glcp (32.8%), 3-linked Glcp (13.5%), 3,6-linked Glcp (1.5%), and 3,6-linked Galp (5.3%). These glycosyl linkage combinations are typical for arabinoxylan, yeast-derived β-glucan, barley-derived β-glucan, and type II arabinogalactan. To clarify the microstructure, BF–I was sequentially degraded via linkage-specific enzymatic hydrolysis using five enzymes. Furthermore, the sugar composition, glycosyl linkage, and reactivity with the β-glucosyl Yariv reagent were analyzed, along with sequencing based on tandem mass spectra of partially degraded fragment fractions. The results confirmed that BF–I comprises a mixture of four different types of polysaccharides (arabinoxylan, yeast-derived β-glucan, barley-derived β-glucan, and type II arabinogalactan) with similar molecular weights. Furthermore, different polysaccharides contribute significantly to cytokine (interleukin-6, -12, and tumor necrosis factor-α) secretion by peritoneal macrophages. Therefore, the potent anti-cancer metastatic activity of BF–I is proposed to be related to the immunostimulatory activities of the four different types of polysaccharides.

A proof of principle study investigating the effects of supplemental concentrated brewer's yeast on markers of gut permeability, inflammation, and fecal metabolites in healthy non-challenged adult sled dogs.

Yeast-derived β-glucans impact immunity, though their effects on gut permeability and inflammation are less understood. Most research has investigated other components of the yeast cell wall, such as the prebiotic mannan- and fructo-oligosaccharides. The objective of this study was to assess the effects of feeding a concentrated yeast product on markers of inflammation (serum amyloid A [SAA] and haptoglobin [Hp]) and oxidative status (malondialdehyde [MDA]), fecal products of fermentation, and gut permeability. Nineteen privately owned domestic Siberian huskies, and one Alaskan husky (9 females: 5 intact, 4 spayed; 11 males: 3 intact, 8 neutered), with an average age of 4.8 ± 2.6 yr and body weight (BW) of 25.6 ± 4.1 kg, were used in this study. Dogs were blocked and randomly allocated to one of two diet groups. Ten dogs received a dry extruded diet. The other 10 received the same diet top dressed with yeast for a daily β-glucan dose of 7 mg/kg BW for 10 wk. Fecal collection, for evaluation of fecal metabolites, and scoring occurred weekly. Gut permeability was assessed using the chromium-labeled ethylenediamine tetra-acetic acid (Cr-EDTA) and iohexol markers prior to the initiation of dietary treatment and after 10 wk of treatment. Blood samples were collected premarker administration and 0.5, 1, 2, 3, 4, 5, and 6 h postadministration. Fasting concentrations of SAA, Hp, and MDA were measured on weeks -1, 2, 4, and 8. Incremental area under the curve (I-AUC) was calculated for serum iohexol and Cr-EDTA concentrations. All data were analyzed using PROC GLIMMIX of SAS with dog as random effect, and week as fixed effect and repeated measure. Dogs receiving treatment tended to have decreased I-AUC of Iohexol (P = 0.10) and Cr-EDTA (P = 0.06) between baseline and cessation of treatment compared to the change over time in I-AUC for control (Ctl) dogs. Treatment dogs had lower Hp concentrations (P ≤ 0.05) than Ctl. There were no differences between treatments for SAA and MDA concentrations (P > 0.05). Fecal arabinose concentrations were greater in treatment (Trt) dogs (P ≤ 0.05) compared to Ctl, though no other fecal metabolites were affected by treatment. There was no difference in the relative frequency of defecations scored at any fecal score between Trt and Ctl dogs, and mean score did not differ between groups (P > 0.10). These data suggest that concentrated brewer's yeast may have the potential to reduce gut permeability without impacting inflammatory status and markers of health in adult dogs.

β-Glucans from Yeast—Immunomodulators from Novel Waste Resources

β-glucans are a large class of complex polysaccharides with bioactive properties, including immune modulation. Natural sources of these compounds include yeast, oats, barley, mushrooms, and algae. Yeast is abundant in various processes, including fermentation, and they are often discarded as waste products. The production of biomolecules from waste resources is a growing trend worldwide with novel waste resources being constantly identified. Yeast-derived β-glucans may assist the host’s defence against infections by influencing neutrophil and macrophage inflammatory and antibacterial activities. β-glucans were long regarded as an essential anti-cancer therapy and were licensed in Japan as immune-adjuvant therapy for cancer in 1980 and new mechanisms of action of these molecules are constantly emerging. This paper outlines yeast β-glucans’ immune-modulatory and anti-cancer effects, production and extraction, and their availability in waste streams.

Yeast beta-glucan mediates histone deacetylase 5-induced angiogenesis in vascular endothelial cells

The role of yeast-derived β-glucan in angiogenesis has not been elucidated because there have been few specific studies on its clinical and physiological significance. Therefore, this study investigated the correlation between β-glucan and histone deacetylase 5 (HDAC5) in human umbilical vein endothelial cells (HUVECs), revealing the role of β-glucan in angiogenesis. We confirmed that HDAC5 was phosphorylated by β-glucan stimulation and released from the nucleus to the cytoplasm. Furthermore, we found that β-glucan-stimulated HDAC5 translocation mediates the transcriptional activation of MEF2. As a result, the expression of KLF2, EGR2, and NR4A2, whose expression is MEF2-dependent and involved in angiogenesis, increased. Thus, we showed the activity of β-glucan in angiogenesis through in vitro and ex vivo assays including cell migration, tube formation, and aortic ring analyses. Specifically, application of an HDAC5 inhibitor repressed MEF2 transcriptional activation in both in vitro and ex vivo angiogenesis. HDAC5 inhibitor LMK235 inhibited the proangiogenic activity of beta-glucan, suggesting that β-glucan induces angiogenesis through HDAC5. These findings suggest that HDAC5 is essential for angiogenesis, and that β-glucan induces angiogenesis. In conclusion, this study demonstrates that β-glucan induces angiogenesis through HDAC5. It also suggests that β-glucan has potential value as a novel therapeutic agent for modulating angiogenesis.

Phase I Trial of Oral Yeast-Derived β-Glucan to Enhance Anti-GD2 Immunotherapy of Resistant High-Risk Neuroblastoma.

Simple SummaryBeta glucans, complex polysaccharides, can prime leukocyte dectin-1 and CR3-receptors and enhance anti-tumor cytotoxicity of monoclonal antibodies. In a phase I study (clinicaltrials.gov NCT00492167), we treated patients with intravenous 3F8 (fixed dose of 10 mg/m2/day × 10 days) and oral BG (dose-escalated from 10–200 mg/kg/day × 17 days in cohorts of 3–6 patients each). Forty-four patients completed 141 cycles of therapy with 3F8 + BG. One patient developed DLT: transient self-limiting hepatic transaminase elevation at a BG dose of 120 mg/kg/day. Overall, 1, 3, 12 and 24 evaluable patients had complete response, partial response, stable and progressive disease, respectively, at the end of treatment. Positive human anti-mouse antibody response and dectin-1 rs3901533 polymorphism were associated with better overall survival. BG dose level and serum BG levels did not correlate with response. BG lacked major toxicity and, in combination with 3F8, demonstrated anti-neuroblastoma activity against resistant disease. The recommended phase II dose was established at 40 mg/kg/day.Beta glucans, complex polysaccharides, prime leukocyte dectin-1 and CR3-receptors and enhance anti-tumor cytotoxicity of complement-activating monoclonal antibodies. We conducted a phase I study (clinicaltrials.gov NCT00492167) to determine the safety of the combination of yeast-derived beta glucan (BG) and anti-GD2 murine monoclonal antibody 3F8 in patients with relapsed or refractory high-risk neuroblastoma. Patients received intravenous 3F8 (fixed dose of 10 mg/m2/day × 10 days) and oral BG (dose-escalated from 10–200 mg/kg/day × 17 days in cohorts of 3–6 patients each). Forty-four patients completed 141 cycles. One patient developed DLT: transient self-limiting hepatic transaminase elevation 5 days after starting BG (120 mg/kg/day). Overall, 1, 3, 12 and 24 evaluable patients had complete response, partial response, stable and progressive disease, respectively, at the end of treatment. Positive human anti-mouse antibody response and dectin-1 rs3901533 polymorphism were associated with better overall survival. BG dose level and serum BG levels did not correlate with response. Progression-free and overall survival at 2 years were 28% and 61%, respectively. BG lacked major toxicity. Treatment with 3F8 plus BG was associated with anti-neuroblastoma responses in patients with resistant disease. Although the maximal tolerated dose for yeast BG was not reached, considering the large volume of oral BG, we recommended 40 mg/kg/day as the phase II dose.

β-Glucan reduces cortisol plasma levels, enhances innate immune system after A. hydrophila inoculation, and has lipolytic effects on the pacu (Piaractus mesopotamicus)

Although β-glucan is a compound widely used to enhance innate immunity in fish, very little is known about its metabolic effects as described in humans and other animals. This study evaluated the effects of dietary β-glucan from Saccharomyces cerevisiae on stress, innate immune and metabolic responses in the pacu (Piaractus mesopotamicus) juveniles. The fish (85.2 ± 24.8 g) were subjected to the following treatments: a) commercial feed CF (0% β-glucan – control); b) CF supplemented with 0.1% β-glucan, and c) CF supplemented with 0.5% β-glucan (eight 130 L tanks/treatment, 72 fish per treatment). The fish were sampled after 15 days of β-glucan administration (basal sampling) to assess the metabolic responses (lipid levels in blood and tissues) and then inoculated with heat-inactivated A. hydrophila to assess the stress and immune responses. For the first time, β-glucan showed a modulatory effect on lipid metabolism in fish. We found a reduction in plasma triglyceride levels, as also in lipid levels in liver, muscle, and visceral depots, in fish fed with β-glucan. The triglyceride levels decreased by 32.9% in fish fed with 0.1% β-glucan, when compared to the control group. Lipid levels decreased by 42.8% and 26.8% in the liver, and by 37.9% and 24.1% in muscle, for fish fed with 0.1% and 0.5% β-glucan, respectively, compared to the control group. Visceral fat decreased by 32.1% and 46.4%, in fish fed with 0.1% and 0.5% β-glucan, respectively. In addition to the lipolytic effect, β-glucan modulated cortisol profile reducing the levels at rest and after inoculation with A. hydrophila bacterin, thereby confirming its immunostimulating action, by increasing the respiratory activity of leukocytes and lysozyme levels 24 h after inoculation. Our results show that, in addition to the immunostimulating action and cortisol reducer effect of the yeast-derived β-glucan, its lipolytic effect is quite promising, as the pacu is considered a fat fish in the market size and a leaner product would bring better features for the consumer.

The Modulating Effect of Dietary Beta-Glucan Supplementation on Expression of Immune Response Genes of Broilers during a Coccidiosis Challenge

Simple SummaryAvian coccidiosis is the leading parasitic disease in the poultry industry and means to control its damages continue to be explored. This study evaluated the feeding effects of a yeast-derived β-glucan on expression of immune response genes in the spleen, thymus, and bursa of commercial broiler chickens during an Eimeria challenge. The study consisted of two dietary treatments (0% or 0.1% β-glucan) each with or without a coccidiosis challenge. There were significant effects from dietary β-glucan, Eimeria challenge, and their interaction for several gene targets in the spleen, thymus, and bursa on days 10 and 14 of age. Based on the current results, supplementation of dietary β-glucan in Eimeria-challenged birds enhanced and modulated the expression of immune response genes during coccidiosis.This study investigated the effects of a yeast-derived β-glucan (Auxoferm YGT) supplementation on mRNA expression of immune response genes in the spleen, thymus, and bursa of broiler chickens during a mixed Eimeria infection. Day (d)-old chicks (n = 1440) were fed diets containing 0% or 0.1% YGT. On d 8 post-hatch, half the replicate pens (n = 8) were challenged with a mixed inoculum of E. acervulina, E. maxima, and E. tenella. On d 10 and d 14 post-hatch, the spleen, thymus, and bursa were collected to evaluate mRNA abundance by quantitative real-time PCR. Data were analyzed using PROC GLIMMIX model (2-way interaction) and differences were established by LS-MEANS with significance reported at p ≤ 0.05. In spleen tissues at d 10, expression of interleukin (IL)-10 and inducible nitric oxide synthase (iNOS) were elevated in both 0.1% YGT-fed challenged and non-challenged birds. In thymus tissues at d 14, expression of IL-10, IL-17F, interferon (IFN)-γ, iNOS, and macrophage migration inhibitory factor (MIF) were elevated in challenged birds fed 0.1% YGT. In bursal tissues at d 10 and d 14, expression of IL-10, IFN-γ, iNOS (d 10 only), and MIF were elevated in 0.1% YGT-fed challenged and non-challenged birds. Dietary β-glucan supplementation to chicken diets modulated their immune response to the Eimeria challenge.

PSVI-24 Immunological Effects of a Purified 1,3/1,6 β-glucan Supplementation in Retorted Canine Diets

Abstract Yeast cell wall products are common functional ingredients capable of “priming” the immune system, specifically in reference to vaccine efficacy. Twenty-four adult, female Beagles were used in a completely randomized design. Three retorted diets were used: control diet (CON), CON plus β-glucan top-dressed daily upon time of feeding (C+B), and CON plus retorted β-glucan included in diet formulation (BG). Following a 7 d adaptation to CON, dogs were fed their respective treatment diets for 42 d and were challenged with an oral Bordetella bronchiseptica vaccine on d 14 with blood collections on d 0, 21, 28, and 42. The objectives of the present study were 1) to evaluate the effects of dietary inclusion of a yeast β-1,3/1,6 glucan (150 ppm) on apparent total tract digestibility (ATTD) of macronutrients, fecal microbiota, and peripheral blood mononuclear cells (PBMC; T-cells, B-cells, and monocytes) of adult dogs and, 2) to test the effects of retorting on the efficacy of these β-glucans. All diets were well-accepted by all dogs. ATTD of both dry matter and crude protein were greater (P < 0.05) for BG than CON and with greater (P < 0.05) energy digestibility for BG than both B+G and CON. Additionally, fecal short-chain and branched-chain fatty acids, ammonia, indole and phenol concentrations did not differ among treatments. No significant treatment by time interactions among treatment groups were observed for any analyzed PBMC. These data suggest that a 150 ppm inclusion of this yeast-derived β-glucan had no detrimental effects on ATTD, fecal characteristics and metabolites, nor any analyzed PBMC; however, due to the absence of differences in immune parameters among treatments, the effect of retorting on the efficacy of this product cannot confidently be assessed with these findings. Higher doses of yeast-derived β-glucan might be needed to elicit an immunological modulation in healthy adult dogs.

Impact of Yeast-Derived β-Glucans on the Porcine Gut Microbiota and Immune System in Early Life.

Piglets are susceptible to infections in early life and around weaning due to rapid environmental and dietary changes. A compelling target to improve pig health in early life is diet, as it constitutes a pivotal determinant of gut microbial colonization and maturation of the host’s immune system. In the present study, we investigated how supplementation of yeast-derived β-glucans affects the gut microbiota and immune function pre- and post-weaning, and how these complex systems develop over time. From day two after birth until two weeks after weaning, piglets received yeast-derived β-glucans or a control treatment orally and were subsequently vaccinated against Salmonella Typhimurium. Faeces, digesta, blood, and tissue samples were collected to study gut microbiota composition and immune function. Overall, yeast-derived β-glucans did not affect the vaccination response, and only modest effects on faecal microbiota composition and immune parameters were observed, primarily before weaning. This study demonstrates that the pre-weaning period offers a ‘window of opportunity’ to alter the gut microbiota and immune system through diet. However, the observed changes were modest, and any long-lasting effects of yeast-derived β-glucans remain to be elucidated.

Conjugation of β-glucans on heat-stable enterotoxin (ST) to enhance the immunogenic response in mouse leucocytes.

Enterotoxigenic Escherichia coli (ETEC) is an important diarrhea-causing pathogen for humans. Heat-stable enterotoxin (ST) plays a crucial role in triggering diarrhea and ETEC pathogenesis. However, ST is a small peptide that lacks immunogenic activity itself but becomes immunogenic when it is coupled to a carrier molecule. In this study, the β-glucans (BG) from yeasts have been used to test their immunomodulatory activity and adjuvant effect on the properties of ST. This study aimed to synthesize and characterize a conjugate of yeast-derived β-glucan with the ST enterotoxin (BG-ST) and evaluate the antigenic and antioxidant activities in mouse splenocytes. Fourier transform infrared spectroscopy and scanning electron microscopy analysis showed new bands and changes in morphology, respectively, confirming ST was successfully coupled to beta glucan. Additionally, according to the enzyme-linked immunosorbent assay (ELISA), conjugation efficiency was almost 90%. Cellular viability, phagocytic cell proportion, and respiratory burst enhanced splenocytes stimulated by BG-ST. In addition, nitric oxide production and antioxidant enzymes increased in cells stimulated with BG-ST, BG and ST. In conclusion, the results revealed the successful conjugation of β-glucan with ST peptide enhancing immune and antioxidant parameters to a greater extent than their individual components.

Differential immunomodulation of porcine bone marrow derived dendritic cells by E. coli Nissle 1917 and β-glucans.

In early life and around weaning, pigs are at risk of developing infectious diseases which compromise animal welfare and have major economic consequences for the pig industry. A promising strategy to enhance resistance against infectious diseases is immunomodulation by feed additives. To assess the immune stimulating potential of feed additives in vitro, bone marrow-derived dendritic cells were used. These cells play a central role in the innate and adaptive immune system and are the first cells encountered by antigens that pass the epithelial barrier. Two different feed additives were tested on dendritic cells cultured from fresh and cryopreserved bone marrow cells; a widely used commercial feed additive based on yeast-derived β-glucans and the gram-negative probiotic strain E. coli Nissle 1917. E. coli Nissle 1917, but not β-glucans, induced a dose-dependent upregulation of the cell maturation marker CD80/86, whereas both feed additives induced a dose-dependent production of pro- and anti-inflammatory cytokines, including TNFα, IL-1β, IL-6 and IL-10. Furthermore, E. coli Nissle 1917 consistently induced higher levels of cytokine production than β-glucans. These immunomodulatory responses could be assessed by fresh as well as cryopreserved in vitro cultured porcine bone marrow-derived dendritic cells. Taken together, these results demonstrate that both β-glucans and E. coli Nissle 1917 are able to enhance dendritic cell maturation, but in a differential manner. A more mature dendritic cell phenotype could contribute to a more efficient response to infections. Moreover, both fresh and cryopreserved bone marrow-derived dendritic cells can be used as in vitro pre-screening tools which enable an evidence based prediction of the potential immune stimulating effects of different feed additives.

Harnessing the power of trained immunity using yeast-derived β-glucan to prevent pancreatic cancer

Abstract Despite the remarkable success of immunotherapy, pancreatic cancer has yet to benefit. This creates a desperate need for therapies that target pancreatic cancer and utilize novel approaches to prevent and treat this lethal disease. Innate immune cells are vital in antitumor immunosurveillance. Recent studies have shown that innate immune cells possess a form of memory termed Trained Immunity (TI), where cells exposed to an initial stimulus undergo epigenetic and metabolic reprograming that causes hyper-responsiveness when exposed to a second signal. It is yet unknown whether inducing TI could protect against tumors, and specifically pancreatic tumors. Here we show that yeast-derived particulate β-glucan, a known TI inducer, results in 90% of an intraperitoneal dose trafficking to the pancreas. This leads to a robust, dose-dependent influx of innate and adaptive immune cells into the pancreas that have enhanced Th1 function. Despite the cellular influx, signs of pancreatitis are absent. In vivo and in vitro studies of β-glucan trained pancreatic macrophages show increased TNFα and IL-6 production when exposed to LPS, pancreatic tumor cells and their supernatant. This indicates that pancreatic macrophages can be trained to protect against pancreatic tumor cells. Depletion of various immune populations suggest that pancreatic macrophages are directly trained by β-glucan, which then stimulate NK and T-cells. In an orthotopic model of pancreatic cancer, β-glucan trained mice show reduced tumor burden and augmented antitumor functions of innate and adaptive cells. Together, this suggests that β-glucan can train pancreatic innate immune cells to have antitumor memory, which can serve as a novel approach to treating pancreatic cancer.

Wheat-derived arabinoxylans reduced M2-macrophage functional activity, but enhanced monocyte-recruitment capacity.

The immunomodulatory properties of non-digestible polysaccharides (NDPs) have been recognized in in vitro and in vivo studies. The latter mostly demonstrated altered frequencies and inflammatory status of immune cells as clinical parameters. Most of the NDP activity will be exerted in the intestine where they can directly interact with macrophages. The predominant macrophage phenotype in the intestine is M2-like, with M1-like macrophages arising during inflammation. Here, we investigated transcriptional and functional impact on these macrophage phenotypes by NDP-treatment (i.e. yeast-derived soluble β-glucan (yeast-βG), apple-derived RG-I (apple-RGI), shiitake-derived β-glucan (shiitake-βG) or wheat-derived arabinoxylan (wheat-AX)). Wheat-AX, and to a lesser extent shiitake-βG and apple-RGI but not yeast-βG, reduced endocytosis and antigen processing capacity of M1- and M2-like macrophages. Moreover, the NDPs, and most notably wheat-AX, strongly induced transcription and secretion of a unique set of cytokines and chemokines. Conditioned medium from wheat-AX-treated M2-like macrophages subsequently demonstrated strongly increased monocyte recruitment capacity. These findings are in line with clinically observed immunomodulatory aspects of NDPs making it tempting to speculate that clinical activity of some NDPs is mediated through enhanced chemoattraction and modifying activity of intestinal immune cells.

Yeast-Derived β-Glucan in Cancer: Novel Uses of a Traditional Therapeutic.

An increased understanding of the complex mechanisms at play within the tumor microenvironment (TME) has emphasized the need for the development of strategies that target immune cells within the TME. Therapeutics that render the TME immune-reactive have a vast potential for establishing effective cancer interventions. One such intervention is β-glucan, a natural compound with immune-stimulatory and immunomodulatory potential that has long been considered an important anti-cancer therapeutic. β-glucan has the ability to modulate the TME both by bridging the innate and adaptive arms of the immune system and by modulating the phenotype of immune-suppressive cells to be immune-stimulatory. New roles for β-glucan in cancer therapy are also emerging through an evolving understanding that β-glucan is involved in a concept called trained immunity, where innate cells take on memory phenotypes. Additionally, the hollow structure of particulate β-glucan has recently been harnessed to utilize particulate β-glucan as a delivery vesicle. These new concepts, along with the emerging success of combinatorial approaches to cancer treatment involving β-glucan, suggest that β-glucan may play an essential role in future strategies to prevent and inhibit tumor growth. This review emphasizes the various characteristics of β-glucan, with an emphasis on fungal β-glucan, and highlights novel approaches of β-glucan in cancer therapy.

Yeast (1 → 3)-(1 → 6)-β-d-glucan alleviates immunosuppression in gemcitabine-treated mice

Gemcitabine (2′-deoxy-2′,2′-difluorocytidine, dFdC) is one of the most effective chemotherapy drugs commonly used for treatment of various tumors. Despite its significant anticancer effects, some adverse effects create obstacles to treatment. The main toxicity of gemcitabine is myelosuppression, which not only reduces patient quality of life, but also hinders further anticancer treatment. In this respect, immunotherapy can address these drawbacks because of its ability to enhance the patient's immune system. To improve immune system function, yeast-derived β-glucans, which are well-known biologic response modifiers, were administered to gemcitabine-treated mice. The in vivo experiment revealed that orally administered yeast (1 → 3)-(1 → 6)-β-d-glucan effectively alleviated myelosuppression associated with gemcitabine-induced pancytopenia. Moreover, analysis of myelopoiesis-related cytokine expression through real-time PCR demonstrated that β-glucan treatment significantly upregulated hematopoietic responses in gemcitabine-treated mice. Furthermore, orally administered β-glucan significantly induced the expression of IFN-γ and IL-2 in splenocytes of gemcitabine-treated mice. It also restored the cytotoxicity of splenocytes against YAC-1 in gemcitabine-treated mice and displayed a positive effect on gemcitabine-damaged bone marrow tissue. In conclusion, yeast β-glucans have the potential to be used as adjuvants for alleviating chemotherapy-induced immunosuppression in patients.