Cereal β-glucan immune modulating activity depends on the polymer fine structure

Barley as a production platform for oral vaccines in sustainable fish aquaculture

Vaccination is the most effective measure to prevent disease outbreaks in fish aquaculture, with oral vaccine administration emerging as the most practical approach. However, oral vaccines face a notable limitation due to insufficient stimulation of the complex gut-associated lymphoid tissue caused by factors such as vaccine degradation, poor absorption, and recognition by the immune cells. An innovative solution to these limitations lies in the plant-based production of recombinant vaccines. Plant cells enable the production and targeted storage of recombinant vaccines in specific cell organelles which ensure superior protection from degradation and contain natural compounds acting as adjuvants. Our study explores the potential of barley (Hordeum vulgare), a globally significant cereal crop, for producing orally administered subunit vaccines against viral infections affecting economically important fish species in the Salmonidae and Cyprinidae families. Through Agrobacterium-mediated transformation of immature barley embryos, we have generated homozygous T2 generation of transgenic barley expressing recombinant antigens of spring viremia of carp virus and infectious salmon anaemia virus. The expression of these plant-based recombinant vaccines was confirmed by immunodetection, which was supported by fluorescence observation, specifically in the seed endosperm. The antigenicity of transgenic plant material containing recombinant antigens was evaluated using an intubation model of common carp (Cyprinus carpio), revealing a substantial upregulation of the immunoglobulin transcripts in both systemic and mucosal tissues over a period of 28 days following a single dose of transgenic antigens. Collectively, these results underscore the potential of barley-based recombinant vaccines for disease prevention in fish aquaculture.

Perspectives in the Application of High, Medium, and Low Molecular Weight Oat β-d-Glucans in Dietary Nutrition and Food Technology-A Short Overview

For centuries human civilization has cultivated oats, and now they are consumed in various forms of food, from instant breakfasts to beverages. They are a nutrient-rich food containing linear mixed-linkage (1 → 3) (1 → 4)-β-d-glucans, which are relatively well soluble in water and responsible for various biological effects: the regulation of the blood cholesterol level, as well as being anti-inflammatory, prebiotic, antioxidant, and tumor-preventing. Numerous studies, especially in the last two decades, highlight the differences in the biological properties of the oat β-d-glucan fractions of low, medium, and high molecular weight. These fractions differ in their features due to variations in bioavailability related to the rheological properties of these polysaccharides, and their association with food matrices, purity, and mode of preparation or modification. There is strong evidence that, under different conditions, the molecular weight may determine the potency of oat-extracted β-d-glucans. In this review, we intend to give a concise overview of the properties and studies of the biological activities of oat β-d-glucan preparations depending on their molecular weight and how they represent a prospective ingredient of functional food with the potential to prevent or modulate various pathological conditions.

Effects of functional ingredients on gut inflammation in Atlantic salmon (Salmo salar L)

Functional feed ingredients are frequently used in feeds for Atlantic salmon, often claimed to improve immune functions in the intestine and reduce severity of gut inflammation. However, documentation of such effects is, in most cases, only indicative. In the present study effects of two packages of functional feed ingredients commonly used in salmon production, were evaluated employing two inflammation models. One model employed soybean meal (SBM) as inducer of a severe inflammation, the other a mixture of corn gluten and pea meal (CoPea) inducing mild inflammation. The first model was used to evaluate effects of two packages of functional ingredients: P1 containing butyrate and arginine, and P2 containing β-glucan, butyrate, and nucleotides. In the second model only the P2 package was tested. A high marine diet was included in the study as a control (Contr). The six diets were fed to salmon (average weight of 177g) in saltwater tanks (57 fish per tank), in triplicate, for 69 days (754 ddg). Feed intake was recorded. The growth rate of the fish was high, highest for the Contr (TGC: 3.9), lowest for SBM fed fish (TGC: 3.4). Fish fed the SBM diet showed severe symptoms of inflammation in the distal intestine as indicated by histological, biochemical, molecular, and physiological biomarkers. The number of differently expressed genes (DEG) between the SBM and Contr fed fish was 849 and comprised genes indicating alteration in immune functions, cellular and oxidative stress, and nutrient digestion, and transport functions. Neither P1 nor P2 altered the histological and functional symptoms of inflammation in the SBM fed fish importantly. Inclusion of P1 altered expression of 81 genes, inclusion of P2 altered 121 genes. Fish fed the CoPea diet showed minor signs of inflammation. Supplementation with P2 did not change these signs. Regarding composition of the microbiota in digesta from the distal intestine, clear differences regarding beta-diversity and taxonomy between Contr, SBM, and CoPea fed fish were observed. In the mucosa the microbiota differences were less clear. The two packages of functional ingredients altered microbiota composition of fish fed the SBM and the CoPea diet towards that of fish fed the Contr diet.

Investigation of the Effects of Monomeric and Dimeric Stilbenoids on Bacteria-Induced Cytokines and LPS-Induced ROS Formation in Bone Marrow-Derived Dendritic Cells

Stilbenoids are anti-inflammatory and antioxidant compounds, with resveratrol being the most investigated molecule in this class. However, the actions of most other stilbenoids are much less studied. This study compares five monomeric (resveratrol, piceatannol, pterostilbene, pinostilbene, and trimethoxy-resveratrol) and two dimeric (dehydro-δ-viniferin and trans-δ-viniferin) stilbenoids for their capability to modulate the production of bacteria-induced cytokines (IL-12, IL-10, and TNF-α), as well as lipopolysaccharide (LPS)-induced reactive oxygen species (ROS), in murine bone marrow-derived dendritic cells. All monomeric species showed dose-dependent inhibition of E. coli-induced IL-12 and TNF-α, whereas only resveratrol and piceatannol inhibited IL-10 production. All monomers, except trimethoxy-resveratrol, inhibited L. acidophilus-induced IL-12, IL-10, and TNF-α production. The dimer dehydro-δ-viniferin remarkably enhanced L. acidophilus-induced IL-12 production. The contrasting effect of resveratrol and dehydro-δ-viniferin on IL-12 production was due, at least in part, to a divergent inactivation of the mitogen-activated protein kinases by the two stilbenoids. Despite having moderate to high total antioxidant activity, dehydro-δ-viniferin was a weak inhibitor of LPS-induced ROS formation. Conversely, resveratrol and piceatannol potently inhibited LPS-induced ROS formation. Methylated monomers showed a decreased antioxidant capacity compared to resveratrol, also depending on the methylation site. In summary, the immune-modulating effect of the stilbenoids depends on both specific structural features of tested compounds and the stimulating bacteria.

Microbial exopolysaccharides-β-glucans-as promising postbiotic candidates in vaccine adjuvants

The urgent task of creating new, enhanced adjuvants is closely related to our comprehension of their mechanisms of action. A few adjuvants have shown sufficient efficacy and low toxicity to be allowed for use in human vaccines, despite the fact that they have a long history and an important function. Adjuvants have long been used without a clear understanding of how precisely they augment the immune response. The rational production of stronger and safer adjuvants has been impeded by this lack of information, which necessitates more mechanistic research to support the development of vaccines. Carbohydrate structures-polygalactans, fructans, β-D-glucans, α-D-glucans, D-galactose, and D-glucose-are desirable candidates for the creation of vaccine adjuvants and immunomodulators because they serve important functions in nature and are often biocompatible, safe, and well tolerated. In this review, we have discussed recent advances in microbial-derived carbohydrate-based adjuvants, their immunostimulatory activity, and the implications of this for vaccine development, along with the critical view on the microbial sources, chemical composition, and biosynthetic pathways.

Structure and function of non-digestible carbohydrates in the gut microbiome

Together with proteins and fats, carbohydrates are one of the macronutrients in the human diet. Digestible carbohydrates, such as starch, starch-based products, sucrose, lactose, glucose and some sugar alcohols and unusual (and fairly rare) α-linked glucans, directly provide us with energy while other carbohydrates including high molecular weight polysaccharides, mainly from plant cell walls, provide us with dietary fibre. Carbohydrates which are efficiently digested in the small intestine are not available in appreciable quantities to act as substrates for gut bacteria. Some oligo- and polysaccharides, many of which are also dietary fibres, are resistant to digestion in the small intestines and enter the colon where they provide substrates for the complex bacterial ecosystem that resides there. This review will focus on these non-digestible carbohydrates (NDC) and examine their impact on the gut microbiota and their physiological impact. Of particular focus will be the potential of non-digestible carbohydrates to act as prebiotics, but the review will also evaluate direct effects of NDC on human cells and systems.

Noni (Morinda citrifolia L.) Fruit Polysaccharides Regulated IBD Mice Via Targeting Gut Microbiota: Association of JNK/ERK/NF-κB Signaling Pathways

Inflammatory bowel disease (IBD) is a disease characterized by intestinal inflammation with immune dysregulation and intestinal microecological imbalance. In a dextran sulfate sodium salt (DSS)-induced IBD mouse model, noni (Morinda citrifolia L.) fruit polysaccharides (NFP) with homogalacturonan and rhamnogalacturonan-I domain decreased the concentration of serum LPS, TNF-α, and IL-17 by 84, 42, and 65%, respectively. It was abolished when intestinal microbiota were depleted by antibiotics. Sequencing analysis of gut microbiota showed an attenuated disruption of the microbial composition in the DSS+NFP group. Targeted metabolomic analysis revealed that NFP upregulated the content of acetic acid, propionic acid, and butyric acid by onefold but reduced isobutyric acid and isovaleric acid contents. NFP also inhibited JNK, ERK, and NF-κB phosphorylation of IBD mice. Taken together, the mechanism of NFP alleviating IBD is related to the intestinal microecological balance to inhibit inflammatory signaling pathways. This study provides a basis for NFP as a cheap intervention for the prevention and treatment of IBD patients.

Strategies to Increase the Biological and Biotechnological Value of Polysaccharides from Agricultural Waste for Application in Healthy Nutrition

Nowadays, there is a growing interest in the extraction and identification of new high added-value compounds from the agro-food industry that will valorize the great amount of by-products generated. Many of these bioactive compounds have shown beneficial effects for humans in terms of disease prevention, but they are also of great interest in the food industry due to their effect of extending the shelf life of foods by their well-known antioxidant and antimicrobial activity. For this reason, an additional research objective is to establish the best conditions for obtaining these compounds from complex by-product structures without altering their activity or even increasing it. This review highlights recent work on the identification and characterization of bioactive compounds from vegetable by-products, their functional activity, new methodologies for the extraction of bioactive compounds from vegetables, possibly increasing their biological activity, and the future of the global functional food and nutraceuticals market.

Anti-Inflammatory Activity of Oat Beta-Glucans in a Crohn's Disease Model: Time- and Molar Mass-Dependent Effects

BACKGROUND

The incidence of Crohn's disease (CD) is increasing worldwide, and it has currently become a serious public health issue in society. The treatment of CD continues throughout a patient's lifetime, and therefore, it is necessary to develop new, effective treatment methods, including dietotherapy. The present study aimed to determine the effects of consumption of oat beta-glucans with different molar mass on colon inflammation (colitis) in the early stages of 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced CD in an animal model.

METHODS

Sprague-Dawley rats (control and TNBS-induced CD) were divided into three dietary groups and fed for 3 days (reflecting acute inflammation) or 7 days (reflecting remission) with a feed containing 1% low (βGl) or high (βGh) molar mass oat beta-glucan or a feed without this polysaccharide. The level of colon inflammatory markers and the expression of cytokines and their receptor genes were measured by ELISA and RT-PCR methods, respectively.

RESULTS

Acute inflammation or remission (3 or 7 days after TNBS administration, respectively) stages of experimentally induced CD were characterized by an increase in the level of inflammatory markers (IL-1, IL-6, IL-10, IL-12, TNF-α, CRP, MPO, COX, and PGE2) and the disruption of some cytokine signaling pathways as well as macro- and microscopic changes of colon tissue. The consumption of oat beta-glucans reduced the level of inflammatory markers and recovered the signaling pathways and histological changes, with stronger effects of βGl after 7 days of colitis.

CONCLUSIONS

Dietary oat beta-glucans can reduce colitis at the molecular and organ level and accelerate CD remission.

An overview on interactions between natural product-derived β-glucan and small-molecule compounds

β-Glucans are widely found in plants and microorganisms, which has a variety of functional activities. During production and application, interactions with other components have a great influence on the structure and functional properties of β-glucan. In this paper, interactions (including non-covalent interaction and free-radical reaction) between natural product derived β-glucan and ascorbic acid, polyphenols, bile acids/salts, metal ion or other compounds were summarized. Besides, the mechanism and influence factors of interactions between β-glucan and small-molecule compounds, and their effects on the functional properties of β-glucan were detailed. This review aims to develop an understanding and practical suggestions on interactions between β-glucan and small-molecule compounds, which is expected to provide a useful reference for processing and application.

Microbiota-dependent and -independent effects of dietary fibre on human health

Dietary fibre, such as indigestible oligosaccharides and polysaccharides, occurs in many foods and has gained considerable importance related to its beneficial effects on host health and specific diseases. Dietary fibre is neither digested nor absorbed in the small intestine and modulates the composition of the gut microbiota. New evidence indicates that dietary fibre also interacts directly with the epithelium and immune cells throughout the gastrointestinal tract by microbiota-independent effects. This review focuses on how dietary fibre improves human health and the reported health benefits that are connected to molecular pathways, in (a) a microbiota-independent manner, via interaction with specific surface receptors on epithelial and immune cells regulating intestinal barrier and immune function, and (b) a microbiota-dependent manner via maintaining intestinal homeostasis by promoting beneficial microbes, including Bifidobacteria and Lactobacilli, limiting the growth, adhesion, and cytotoxicity of pathogenic microbes, as well as stimulating fibre-derived microbial short-chain fatty acid production. LINKED ARTICLES: This article is part of a themed section on The Pharmacology of Nutraceuticals. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v177.6/issuetoc.

β-glucans as potential immunoadjuvants: A review on the adjuvanticity, structure-activity relationship and receptor recognition properties

β-glucans, a group of polysaccharides exist in many organism species such as mushrooms, yeasts, oats, barley, seaweed, but not mammalians, have a variety of biological activities and applications in drugs and other healthcare products. In recent years, β-glucans have been studied as adjuvants in anti-infection vaccines as well as immunomodulators in anti-cancer immunotherapy. β-glucans can regulate immune responses when administered alone and can connect innate and adaptive immunity to improve immunogenicity of vaccines. When β-glucans act as immunostimulants or adjuvants, a set of receptors have been revealed to recognize β-glucans, including dectin-1, complement receptor 3 (CR3), CD5, lactosylceramide, and so on. Therefore, this review is mainly focused on the application of β-glucans as immune adjuvants, the receptors of β-glucans, as well as their structure and activity relationship which will benefit future research of β-glucans.

Arabinoxylan hydrolyzates as immunomodulators in Caco-2 and HT-29 colon cancer cell lines

The use of plant derived polysaccharides as health promoters has gained immense interest in the past few years. Arabinoxylan (AX) is the predominant non-starch polysaccharide in cereals and grasses including wheat. The current research aimed to investigate the structure-function relationship of arabinoxylan hydrolyzates (AXH), obtained by the enzymatic hydrolysis of AX using xylanase and arabinofuranosidase as immunomodulators in two colon cancer cell lines: Caco-2 and HT-29. Fine structural details had a strong correlation with the immunological properties of the wheat AXH. As a general trend, as the presence of arabinose substitution increased in the AXH, the production of proinflammatory cytokines, IL-8 and TNF-α, decreased in both cell lines. Thus, AXH with a higher degree of arabinose substitution might be better adept in lowering inflammation in colon cancer cells.

Complementary effects of cereal and pulse polyphenols and dietary fiber on chronic inflammation and gut health

Cereal grains and grain pulses are primary staples often consumed together, and contribute a major portion of daily human calorie and protein intake globally. Protective effects of consuming whole grain cereals and grain pulses against various inflammation-related chronic diseases are well documented. However, potential benefits of combined intake of whole cereals and pulses beyond their complementary amino acid nutrition is rarely considered in literature. There is ample evidence that key bioactive components of whole grain cereals and pulses are structurally different and thus may be optimized to provide synergistic/complementary health benefits. Among the most important whole grain bioactive components are polyphenols and dietary fiber, not only because of their demonstrated biological function, but also their major impact on consumer choice of whole grain/pulse products. This review highlights the distinct structural differences between key cereal grain and pulse polyphenols and non-starch polysaccharides (dietary fiber), and the evidence on specific synergistic/complementary benefits of combining the bioactive components from the two commodities. Interactive effects of the polyphenols and fiber on gut microbiota and associated benefits to colon health, and against systemic inflammation, are discussed. Processing technologies that can be used to further enhance the interactive benefits of combined cereal-pulse bioactive compounds are highlighted.

Barley beta-glucans varying in molecular mass and oligomer structure affect cecal fermentation and microbial composition but not blood lipid profiles in hypercholesterolemic rats

There is an unmet need for appealing and functional barley β-glucan (BG) food matrices that can provide sufficient and active BG doses to consumers.

Arabinoxylans, gut microbiota and immunity

Arabinoxylan (AX) is a non-starch polysaccharide found in many cereal grains and is considered as a dietary fiber. Despite their general structure, there is structural heterogeneity among AX originating from different botanical sources. Furthermore, the extraction procedure and hydrolysis by xylolytic enzymes can further render differences to theses AX. The aim of this review was to address the effects of AX on the gut bacteria and their immunomodulatory properties. Given the complex structure of AX, we also aimed to discuss how the structural heterogeneity of AX affects its role in bacterial growth and immunomodulation. The existing literature indicates the role of fine structural details of AX on its potential as polysaccharides that can impact the gut associated microbial growth and immune system.

Sugar-coated: exopolysaccharide producing lactic acid bacteria for food and human health applications

The human enteric microbiome represents a veritable organ relied upon by the host for a range of metabolic and homeostatic functions.