Innate Immune Training of Granulopoiesis Promotes Anti-tumor Activity.

Trained innate immunity, induced via modulation of mature myeloid cells or their bone marrow progenitors, mediates sustained increased responsiveness to secondary challenges. Here, we investigated whether anti-tumor immunity can be enhanced through induction of trained immunity. Pre-treatment of mice with ß-glucan, a fungal-derived prototypical agonist of trained immunity, resulted in diminished tumor growth. The anti-tumor effect of ß-glucan-induced trained immunity was associated with transcriptomic and epigenetic rewiring of granulopoiesis and neutrophil reprogramming toward an anti-tumor phenotype; this process required type I interferon signaling irrespective of adaptive immunity in the host. Adoptive transfer of neutrophils from ß-glucan-trained mice to naive recipients suppressed tumor growth in the latter in a ROS-dependent manner. Moreover, the anti-tumor effect of ß-glucan-induced trained granulopoiesis was transmissible by bone marrow transplantation to recipient naive mice. Our findings identify a novel and therapeutically relevant anti-tumor facet of trained immunity involving appropriate rewiring of granulopoiesis.

Modulation of Myelopoiesis Progenitors Is an Integral Component of Trained Immunity.

Trained innate immunity fosters a sustained favorable response of myeloid cells to a secondary challenge, despite their short lifespan in circulation. We thus hypothesized that trained immunity acts via modulation of hematopoietic stem and progenitor cells (HSPCs). Administration of ß-glucan (prototypical trained-immunity-inducing agonist) to mice induced expansion of progenitors of the myeloid lineage, which was associated with elevated signaling by innate immune mediators, such as IL-1ß and granulocyte-macrophage colony-stimulating factor (GM-CSF), and with adaptations in glucose metabolism and cholesterol biosynthesis. The trained-immunity-related increase in myelopoiesis resulted in a beneficial response to secondary LPS challenge and protection from chemotherapy-induced myelosuppression in mice. Therefore, modulation of myeloid progenitors in the bone marrow is an integral component of trained immunity, which to date, was considered to involve functional changes of mature myeloid cells in the periphery.

ß-Glucan Reverses the Epigenetic State of LPS-Induced Immunological Tolerance.

Innate immune memory is the phenomenon whereby innate immune cells such as monocytes or macrophages undergo functional reprogramming after exposure to microbial components such as lipopolysaccharide (LPS). We apply an integrated epigenomic approach to characterize the molecular events involved in LPS-induced tolerance in a time-dependent manner. Mechanistically, LPS-treated monocytes fail to accumulate active histone marks at promoter and enhancers of genes in the lipid metabolism and phagocytic pathways. Transcriptional inactivity in response to a second LPS exposure in tolerized macrophages is accompanied by failure to deposit active histone marks at promoters of tolerized genes. In contrast, ß-glucan partially reverses the LPS-induced tolerance in vitro. Importantly, ex vivo ß-glucan treatment of monocytes from volunteers with experimental endotoxemia re-instates their capacity for cytokine production. Tolerance is reversed at the level of distal element histone modification and transcriptional reactivation of otherwise unresponsive genes. VIDEO ABSTRACT.

Utilization of dietary mixed-linkage ß-glucans by the Firmicute Blautia producta.

The ß-glucans are structurally varied, naturally occurring components of the cell walls, and storage materials of a variety of plant and microbial species. In the human diet, mixed-linkage glucans [MLG - ß-(1,3/4)-glucans] influence the gut microbiome and the host immune system. Although consumed daily, the molecular mechanism by which human gut Gram-positive bacteria utilize MLG largely remains unknown. In this study, we used Blautia producta ATCC 27340 as a model organism to develop an understanding of MLG utilization. B. producta encodes a gene locus comprising a multi-modular cell-anchored endo-glucanase (BpGH16MLG), an ABC transporter, and a glycoside phosphorylase (BpGH94MLG) for utilizing MLG, as evidenced by the upregulation of expression of the enzyme- and solute binding protein (SBP)-encoding genes in this cluster when the organism is grown on MLG. We determined that recombinant BpGH16MLG cleaved various types of ß-glucan, generating oligosaccharides suitable for cellular uptake by B. producta. Cytoplasmic digestion of these oligosaccharides is then performed by recombinant BpGH94MLG and ß-glucosidases (BpGH3-AR8MLG and BpGH3-X62MLG). Using targeted deletion, we demonstrated BpSBPMLG is essential for B. producta growth on barley ß-glucan. Furthermore, we revealed that beneficial bacteria, such as Roseburia faecis JCM 17581T, Bifidobacterium pseudocatenulatum JCM 1200T, Bifidobacterium adolescentis JCM 1275T, and Bifidobacterium bifidum JCM 1254, can also utilize oligosaccharides resulting from the action of BpGH16MLG. Disentangling the ß-glucan utilizing the capability of B. producta provides a rational basis on which to consider the probiotic potential of this class of organism.

The effect of Schizophyllan on the differentiation of osteoclasts and osteoblasts.

Schizophyllan (SPG), a ß-glucan from Schizophyllum commune, is recognized for its antioxidant, immunoregulatory, and anticancer activities. In this study, its effects on bone cells, particularly osteoclasts and osteoblasts, were examined. We demonstrated that SPG dose-dependently inhibited osteoclastogenesis and reduced gene expression associated with osteoclast differentiation. SPG also decreased bone resorption and F-actin ring formation. This inhibition could have been due to the downregulation of transcription factors c-Fos and nuclear factor of activated T cells 1 (NFATc1) via the MAPKs (JNK and p38), IκBα, and PGC1ß/PPARγ pathways. In coculture, SPG lowered osteoclastogenic activity in calvaria-derived osteoblasts by reducing macrophage colony-stimulating factor (M-CSF) and receptor activator of nuclear factor-κB ligand (RANKL) expression. In addition, SPG slightly enhanced osteoblast differentiation, as evidenced by increased differentiation marker gene expression and alizarin red staining. It also exhibited antiresorptive effects in a lipopolysaccharide-induced calvarial bone loss model. These results indicated a dual role of SPG in bone cell regulation by suppressing osteoclastogenesis and promoting osteoblast differentiation. Thus, SPG could be a therapeutic agent for bone resorption-related diseases such as osteoporosis, rheumatoid arthritis, and periodontitis.

ß-1,3-Glucan recognition by Acanthamoeba castellanii as a putative mechanism of amoeba-fungal interactions.

In this study, we conducted an in-depth analysis to characterize potential Acanthamoeba castellanii (Ac) proteins capable of recognizing fungal ß-1,3-glucans. Ac specifically anchors curdlan or laminarin, indicating the presence of surface ß-1,3-glucan-binding molecules. Using optical tweezers, strong adhesion of laminarin- or curdlan-coated beads to Ac was observed, highlighting their adhesive properties compared to controls (characteristic time τ of 46.9 and 43.9 s, respectively). Furthermore, Histoplasma capsulatum (Hc) G217B, possessing a ß-1,3-glucan outer layer, showed significant adhesion to Ac compared to a Hc G186 strain with an α-1,3-glucan outer layer (τ of 5.3 s vs τ 83.6 s). The addition of soluble ß-1,3-glucan substantially inhibited this adhesion, indicating the involvement of ß-1,3-glucan recognition. Biotinylated ß-1,3-glucan-binding proteins from Ac exhibited higher binding to Hc G217B, suggesting distinct recognition mechanisms for laminarin and curdlan, akin to macrophages. These observations hinted at the ß-1,3-glucan recognition pathway's role in fungal entrance and survival within phagocytes, supported by decreased fungal viability upon laminarin or curdlan addition in both phagocytes. Proteomic analysis identified several Ac proteins capable of binding ß-1,3-glucans, including those with lectin/glucanase superfamily domains, carbohydrate-binding domains, and glycosyl transferase and glycosyl hydrolase domains. Notably, some identified proteins were overexpressed upon curdlan/laminarin challenge and also demonstrated high affinity to ß-1,3-glucans. These findings underscore the complexity of binding via ß-1,3-glucan and suggest the existence of alternative fungal recognition pathways in Ac.IMPORTANCEAcanthamoeba castellanii (Ac) and macrophages both exhibit the remarkable ability to phagocytose various extracellular microorganisms in their respective environments. While substantial knowledge exists on this phenomenon for macrophages, the understanding of Ac's phagocytic mechanisms remains elusive. Recently, our group identified mannose-binding receptors on the surface of Ac that exhibit the capacity to bind/recognize fungi. However, the process was not entirely inhibited by soluble mannose, suggesting the possibility of other interactions. Herein, we describe the mechanism of ß-1,3-glucan binding by A. castellanii and its role in fungal phagocytosis and survival within trophozoites, also using macrophages as a model for comparison, as they possess a well-established mechanism involving the Dectin-1 receptor for ß-1,3-glucan recognition. These shed light on a potential parallel evolution of pathways involved in the recognition of fungal surface polysaccharides.

PET imaging of Aspergillus infection using Zirconium-89 labeled anti-ß-glucan antibody fragments.

PURPOSE: Invasive fungal diseases, such as pulmonary aspergillosis, are common life-threatening infections in immunocompromised patients and effective treatment is often hampered by delays in timely and specific diagnosis. Fungal-specific molecular imaging ligands can provide non-invasive readouts of deep-seated fungal pathologies. In this study, the utility of antibodies and antibody fragments (Fab) targeting ß-glucans in the fungal cell wall to detect Aspergillus infections was evaluated both in vitro and in preclinical mouse models. METHODS: The binding characteristics of two commercially available ß-glucan antibody clones and their respective antigen-binding Fabs were tested using biolayer interferometry (BLI) assays and immunofluorescence staining. In vivo binding of the Zirconium-89 labeled antibodies/Fabs to fungal pathogens was then evaluated using PET/CT imaging in mouse models of fungal infection, bacterial infection and sterile inflammation. RESULTS: One of the evaluated antibodies (HA-ßG-Ab) and its Fab (HA-ßG-Fab) bound to ß-glucans with high affinity (KD = 0.056 & 21.5 nM respectively). Binding to the fungal cell wall was validated by immunofluorescence staining and in vitro binding assays. ImmunoPET imaging with intact antibodies however showed slow clearance and high background signal as well as nonspecific accumulation in sites of infection/inflammation. Conversely, specific binding of [89Zr]Zr-DFO-HA-ßG-Fab to sites of fungal infection was observed when compared to the isotype control Fab and was significantly higher in fungal infection than in bacterial infection or sterile inflammation. CONCLUSIONS: [89Zr]Zr-DFO-HA-ßG-Fab can be used to detect fungal infections in vivo. Targeting distinct components of the fungal cell wall is a viable approach to developing fungal-specific PET tracers.

Microglia-Dependent Reversal of Depression-Like Behaviors in Chronically Stressed Mice by Administration of a Specific Immuno-stimulant ß-Glucan.

In recent years, the decline of microglia in the hippocampus has been shown to play a role in the development of depression, and its reversal shows marked antidepressant-like effects. ß-glucan is a polysaccharide from Saccharomyces cerevisiae and has numerous beneficial effects on the nervous system, including improving axon regeneration and cognition. Considering its immuno-stimulatory activities in cultured microglia and brain tissues, we hypothesize that ß-glucan may be a potential candidate to correct the functional deficiency of microglia and thereby alleviate depression-like behaviors in chronically stressed animals. An expected, our results showed that a single injection of ß-glucan 5 h before behavioral tests at a dose of 10 or 20 mg/kg, but not at a dose of 5 mg/kg, reversed the depression-like behavior induced by chronic stress in mice in the tail suspension test, forced swimming test, and sucrose preference test. The effect of ß-glucan (20 mg/kg) also showed time-dependent properties that were statistically significant 5 and 8, but not 3, hours after drug injection and persisted for at least 7 days. Fourteen days after ß-glucan injection, no antidepressant-like effect was observed anymore. However, this effect was overcome by a second ß-glucan injection (20 mg/kg) 14 days after the first ß-glucan injection. Stimulation of microglia appeared to mediate the antidepressant-like effect of ß-glucan, because both inhibition of microglia and their depletion prevented the antidepressant-like effect of ß-glucan. Based on these effects of ß-glucan, ß-glucan administration could be developed as a new strategy for the treatment of depression.

Alteration of ß-glucan in the emerging fungal pathogen Candida auris leads to immune evasion and increased virulence.

Candida auris is an emerging pathogenic yeast that has been categorized as a global public health threat and a critical priority among fungal pathogens. Despite this, the immune response against C. auris infection is still not well understood. Hosts fight Candida infections through the immune system that recognizes pathogen-associated molecular patterns such as ß-glucan, mannan, and chitin on the fungal cell wall. In this study, levels of ß-glucan and mannan exposures in C. auris grown under different physiologically relevant stimuli were quantified by flow cytometry-based analysis. Lactate, hypoxia, and sublethal concentration of fluconazole trigger a decrease in surface ß-glucan while low pH triggers an increase in ß-glucan. There is no inverse pattern between exposure levels of ß-glucan and mannan in the cell wall architecture among the three clades. To determine the effect of cell wall remodeling on the immune response, a phagocytosis assay was performed, followed by quantification of released cytokines by ELISA. Lactate-induced decrease in ß-glucan leads to reduced uptake of C. auris by PMA-differentiated THP-1 and RAW 264.7 macrophages. Furthermore, reduced production of CCL3/MIP-1⍺ but not TNF-⍺ and IL-10 were observed. An in vivo infection analysis using silkworms reveals that a reduction in ß-glucan triggers an increase in the virulence of C. auris. This study demonstrates that ß-glucan alteration occurs in C. auris and serves as an escape mechanism from immune cells leading to increased virulence.

Saccharomyces cerevisiae ß-glucan improves the response of trained macrophages to severe P. aeruginosa infections.

OBJECTIVE P. AERUGINOSA: (PA), the major pathogen of lung cystic fibrosis (CF), polarizes macrophages into hyperinflammatory tissue damaging phenotype. The main aim of this study was to verify whether training of macrophages with ß-glucan might improve their response to P. aeruginosa infections. METHODS: To perform this task C57BL/6 mice sensitive to infections with P. aeruginosa were used. Peritoneal macrophages were trained with Saccharomyces cerevisiae ß-glucan and exposed to PA57, the strong biofilm-forming bacterial strain isolated from the patient with severe lung CF. The release of cytokines and the expression of macrophage phenotypic markers were measured. A quantitative proteomic approach was used for the characterization of proteome-wide changes in macrophages. The effect of in vivo ß-glucan-trained macrophages in the air pouch model of PA57 infection was investigated. In all experiments the effect of trained and naïve macrophages was compared. RESULTS: Trained macrophages acquired a specific phenotype with mixed pro-inflammatory and pro-resolution characteristics, however they retained anti-bacterial properties. Most importantly, transfer of trained macrophages into infected air pouches markedly ameliorated the course of infection. PA57 bacterial growth and formation of biofilm were significantly suppressed. The level of serum amyloid A (SAA), a systemic inflammation biomarker, was reduced. CONCLUSIONS: Training of murine macrophages with S. cerevisiae ß-glucan improved macrophage defense properties along with inhibition of secretion of some detrimental inflammatory agents. We suggest that training of macrophages with such ß-glucans might be a new therapeutic strategy in P. aeruginosa biofilm infections, including CF, to promote eradication of pathogens and resolution of inflammation.

Physical impediment to sodium houttuyfonate conversely reinforces ß-glucan exposure stimulated innate immune response to Candida albicans.

Candida albicans is a dimorphic opportunistic pathogen in immunocompromised individuals. We have previously demonstrated that sodium houttuyfonate (SH), a derivative of medicinal herb Houttuynia cordata Thunb, was effective for antifungal purposes. However, the physical impediment of SH by C. albicans ß-glucan may weaken the antifungal activity of SH. In this study, the interactions of SH with cell wall (CW), extracellular matrix (EM), CW ß-glucan, and a commercial ß-glucan zymosan A (ZY) were inspected by XTT assay and total plate count in a standard reference C. albicans SC5314 as well as two clinical fluconazole-resistant strains Z4935 and Z5172. After treatment with SH, the content and exposure of CW ß-glucan, chitin, and mannan were detected, the fungal clearance by phagocytosis of RAW264.7 and THP-1 was examined, and the gene expressions and levels of cytokines TNF-ɑ and IL-10 were also monitored. The results showed that SH could be physically impeded by ß-glucan in CW, EM, and ZY. This impediment subsequently triggered the exposure of CW ß-glucan and chitin with mannan masked in a time-dependent manner. SH-induced ß-glucan exposure could significantly enhance the phagocytosis and inhibit the growth of C. albicans. Meanwhile, the SH-pretreated fungal cells could greatly stimulate the cytokine gene expressions and levels of TNF-ɑ and IL-10 in the macrophages. In sum, the strategy that the instant physical impediment of C. albicans CW to SH, which can induce the exposure of CW ß-glucan may be universal for C. albicans in response to physical deterrent by antifungal drugs.

GFPBW1, a ß-glucan from Grifola frondosa as vaccine adjuvant: APCs activation and maturation.

Adjuvants for vaccines with characteristics of improving adaptive immunity particularly via leverage of antigen presenting cells (APCs) are currently lacking. In a previous work we obtained a new soluble 300 kDa homogeneous ß-glucan named GFPBW1 from the fruit bodies of Granola frondosa. GFPBW1 could activate macrophages by targeting dendritic cell associated C-type lectin 1 (Dectin-1)/Syk/NF-κB signaling to achieve antitumour effects. In this study the adjuvant effects of GFPBW1 were explored with OVA-antigen and B16-OVA tumor model. We showed that GFPBW1 (5, 50, 500 µg/mL) dose-dependently promoted activation and maturation of APCs in vitro by increasing CD80, CD86 and MHC II expression. We immunized female mice with OVA in combination with GFPBW1 (50 or 300 µg) twice with an interval of two weeks. GFPBW1 markedly and dose-dependently increased OVA-specific antibody titers of different subtypes including IgG1, IgG2a, IgG2b and IgG3, suggesting that it could serve as an adjuvant for both Th1 and Th2 type immune responses. Furthermore, GFPBW1 in combination with aluminum significantly increased the titers of OVA-specific IgG2a and IgG2b, but not those of IgG1, suggesting that GFPBW1 could be used as a co-adjuvant of aluminum to compensate for Th1 deficiency. For mice immunized with OVA plus GFPBW1, no obvious pathological injury was observed in either major organs or injection sites, and no abnormalities were noted for any of the hematological parameters. When GFPBW1 served as an adjuvant in the B16-OVA cancer vaccine models, it could accomplish entire tumor suppression with preventive vaccines, and enhance antitumour efficacy with therapeutic vaccines. Differentially expressed genes were found to be enriched in antigen processing process, specifically increased tumor infiltration of DCs, B1 cells and plasma cells in the OVA plus GFPBW1 group, in accordance with its activation and maturation function of APCs. Collectively, this study systematically describes the properties of GFPBW1 as a novel potent and safe adjuvant and highlights its great potential in vaccine development.

Maitake Beta-Glucan Enhances the Therapeutic Effect of Trastuzumab via Antibody-Dependent Cellular Cytotoxicity and Complement-Dependent Cytotoxicity.

Trastuzumab, an anti-HER2 monoclonal antibody, is the mainstay treatment for of HER2-positive breast cancer. However, trastuzumab resistance is often observed during treatment. Therefore, new therapeutic strategies are needed to enhance the clinical benefits of trastuzumab. Maitake ß-glucan MD-Fraction, isolated from Grifola frondosa, inhibits tumor growth by enhancing immune responses. In this study, we examined the effect of MD-Fraction on trastuzumab treatment of HER2-positive breast cancer. MD-Fraction did not directly inhibit the survival of HER2-positive breast cancer cells, alone or in the presence of trastuzumab in vitro. In HER2-positive xenograft models, the combination of MD-Fraction and trastuzumab was more effective than trastuzumab alone. Peripheral blood lymphocytes and splenic natural killer cells isolated from BALB/c nu/nu mice treated with MD-Fraction showed enhanced trastuzumab-induced antibody-dependent cellular cytotoxicity (ADCC) ex vivo. MD-Fraction-treated macrophages and neutrophils did not show enhanced trastuzumab cytotoxicity in the presence of heat-inactivated serum, but they showed enhanced cytotoxicity in the presence of native serum. These results suggest that MD-Fraction-treated macrophages and neutrophils enhance trastuzumab-induced complement-dependent cellular cytotoxicity (CDCC). Treatment of HER2-positive breast cancer cells with MD-Fraction in the presence of trastuzumab and native serum increased C3a release and tumor cell lysis in a dose-dependent manner, indicating that MD-Fraction enhanced trastuzumab-induced complement-dependent cytotoxicity (CDC) by activating the complement system. This study demonstrates that the combination of trastuzumab and MD-Fraction exerts a greater antitumor effect than trastuzumab alone by enhancing ADCC, CDCC, and CDC in HER2-positive breast cancer.

Attenuation of inflammatory bowel disease by oral administration of mucoadhesive polydopamine-coated yeast ß-glucan via ROS scavenging and gut microbiota regulation.

Treatment for inflammatory bowel disease (IBD) is challenging since current anti-inflammatory and immunosuppressive therapies do not address the underlying causes of the illness, which include increased levels of reactive oxygen species (ROS) and dysbiosis of the gut commensal microbiota. Additionally, these treatments often have systemic off-target effects and adverse side effects. In this study, we have developed a prebiotic yeast ß-glucan nanocomplex coated with bio-adhesive polydopamine (YBNs@PDA) to effectively prolong their retention time in the gastrointestinal (GI) tract. The oral administration of YBNs@PDA restored the epithelium barriers, reduced ROS levels, and minimized systemic drug exposure while improved therapeutic efficacy in an acute colitis mouse model. Furthermore, 16S ribosomal RNA genes sequencing demonstrated a higher richness and diversity in gut microflora composition following the treatments. In particular, YBNs@PDA markedly augmented the abundance of Lachnospiraceae NK4A136 and Bifidobacterium, both of which are probiotics with crucial roles in relieving colitis via retaining gut homeostasis. Cumulatively, these results demonstrate that the potential of YBNs@PDA as a novel drug-free, ROS-scavenging and gut microbiota regulation nanoplatform for the treatment of GI disorders.

QTL Analysis of ß-Glucan Content and Other Grain Traits in a Recombinant Population of Spring Barley.

Barley with high grain ß-glucan content is valuable for functional foods. The identification of loci for high ß-glucan content is, thus, of great importance for barley breeding. Segregation mapping for the content in ß-glucan and other barley grain components (starch, protein, lipid, ash, phosphorous, calcium, sodium) was performed using the progeny of the cross between Glacier AC38, a mutant with high amylose, and CDC Fibar, a high ß-glucan waxy cultivar. The offspring of this cross showed transgressive segregation for ß-glucan content. Linkage analysis based on single-nucleotide polymorphism (SNP) molecular markers was used for the genotyping of the parents and recombinant inbred lines (RILs). Two Quantitative Trait Loci (QTL) for ß-glucan content and several QTL for other grain components were found. The former ones, located on chromosomes 1H and 7H, explained 27.9% and 27.4% of the phenotypic variance, respectively. Glacier AC38 provided the allele for high ß-glucan content at the QTL on chromosome 1H, whereas CDC Fibar contributed the allele at the QTL on chromosome 7H. Their recombination resulted in a novel haplotype with higher ß-glucan content, up to 18.4%. Candidate genes are proposed for these two QTL: HvCslF9, involved in ß-glucan biosynthesis, for the QTL on chromosome 1H; Horvu_PLANET_7H01G069300, a gene encoding an ATP-Binding Cassette (ABC) transporter, for the QTL on chromosome 7H.

Structural Characterization and Antioxidant Activity of ß-Glucans from Highland Barley Obtained with Ultrasonic-Microwave-Assisted Extraction.

In order to efficiently extract ß-glucan from highland barley (HBG) and study its structural characterization and antioxidant activity, ultrasonic-microwave-assisted extraction (UME) was optimized by the response surface method (RSM). Under the optimal extraction conditions of 25.05 mL/g liquid-solid ratio, 20 min ultrasonic time, and 480 W microwave intensity, the DPPH radical scavenging activity of HBG reached 25.67%. Two polysaccharide fractions were purified from HBG, namely HBG-1 and HBG-2. Structural characterization indicated that HBG-1 and HBG-2 had similar functional groups, glycosidic linkages, and linear and complex chain conformation. HBG-1 was mainly composed of glucose (98.97%), while HBG-2 primarily consisted of arabinose (38.23%), galactose (22.01%), and xylose (31.60%). The molecular weight of HBG-1 was much smaller than that of HBG-2. Both HBG-1 and HBG-2 exhibited concentration-dependent antioxidant activity, and HBG-1 was more active. This study provided insights into the efficient extraction of HBG and further investigated the structure and antioxidant activities of purified components HBG-1 and HBG-2. Meanwhile, the results of this study imply that HBG has the potential to be an antioxidant in foods and cosmetics.

Preparation of a Novel Oat ß-Glucan-Chromium(III) Complex and Its Hypoglycemic Effect and Mechanism.

This study synthesized a novel oat ß-glucan (OBG)-Cr(III) complex (OBG-Cr(III)) and explored its structure, inhibitory effects on α-amylase and α-glucosidase, and hypoglycemic activities and mechanism in vitro using an insulin-resistant HepG2 (IR-HepG2) cell model. The Cr(III) content in the complex was found to be 10.87%. The molecular weight of OBG-Cr(III) was determined to be 7.736 × 104 Da with chromium ions binding to the hydroxyl groups of OBG. This binding resulted in the increased asymmetry and altered spatial conformation of the complex along with significant changes in morphology and crystallinity. Our findings demonstrated that OBG-Cr(III) exhibited inhibitory effects on α-amylase and α-glucosidase. Furthermore, OBG-Cr(III) enhanced the insulin sensitivity of IR-HepG2 cells, promoting glucose uptake and metabolism more efficiently than OBG alone. The underlying mechanism of its hypoglycemic effect involved the modulation of the c-Cbl/PI3K/AKT/GLUT4 signaling pathway, as revealed by Western blot analysis. This research not only broadened the applications of OBG but also positioned OBG-Cr(III) as a promising Cr(III) supplement with enhanced hypoglycemic benefits.

Structural and rheological characterization of water-soluble and alkaline-soluble fibers from hulless barley.

BACKGROUND: Highland hulless barley has garnered attention as a promising economic product and a potential healthy food ingredient. The present study aimed to comprehensively investigate the molecular structure of extractable fibers obtained from a specific highland hulless barley. Water-soluble fiber (WSF) and alkaline-soluble fiber (ASF) were extracted using enzymatic digestion and an alkaline method, respectively. The purified fibers underwent a thorough investigation for their structural characterization. RESULTS: The monosaccharide composition revealed that WSF primarily consisted of glucose (91.7%), whereas ASF was composed of arabinose (54.5%) and xylose (45.5%), indicating the presence of an arabinoxylan molecule with an A/X ratio of 1.2. The refined structural information was further confirmed through methylation, 1 H NMR and Fourier-transform infrared spectroscopy analyses. WSF fiber exclusively exhibited α-anomeric patterns, suggesting it was an α-glucan. It has a low molecular weight of 5 kDa, as determined by gel permeation chromatography. Conversely, ASF was identified as a heavily branched arabinoxylan with 41.55% of '→2,3,4)-Xylp-(1→' linkages. ASF and WSF exhibited notable differences in their morphology, water absorption capabilities and rheological properties. CONCLUSION: Based on these findings, molecular models of WSF and ASF were proposed. The deep characterization of these fiber structures provides valuable insights into their physicochemical and functional properties, thereby unlocking their potential applications in the food industry. © 2023 Society of Chemical Industry.

Higher intake of ß-glucan impairs reproduction in a female teleost, Tor putitora (Hamilton, 1822).

Although the immuno-modulatory and stress-relieving properties of ß-glucan is well elucidated in humans and other animal models, including fish, its role as a dietary supplement on reproduction is extremely scarce. Therefore, in this study, adult female fish were fed one of four test diets having 0 (control), 0.5, 1, and 1.5% ß-D-glucan for 130 days and its effect on reproductive performance, ovarian and liver histology, sex hormones, and transcript abundance of selected reproduction-related genes was assessed. Low dietary intake of ß-glucan improved fertilization and hatching rates (p<0.05). The relative fecundity and percentage of spawning females were higher (non-significant) in 0.5% ß-glucan-fed groups. Surprisingly, even after 130 days, spawning did not occur in 1.5% ß-glucan-fed individuals. Irrespective of ß-glucan intake, all the brooders recorded similar plasma 17ß-estradiol and maturation-inducing hormone (p>0.05). Higher intake of ß-glucan (1.5%) upregulated aromatase genes without a parallel increase in 17ß-estradiol. However, plasma vitellogenin increased with increasing ß-glucan up to 1.0% then declined at 1.5% (p<0.05). The fish that received control, 0.5, and 1.5% ß-glucan recorded similar vitellogenin levels in their plasma. Significantly higher plasma cortisol was evidenced in 1.5% ß-glucan fed brooders (p<0.05). Histologically, higher follicular atresia and leaking of yolk material was evidenced in 1.5% ß-glucan-fed group. Liver histology revealed the highest nutrient/lipid accumulation in fish that received 1.0% and 1.5% ß-glucan. This study demonstrated the stimulatory effect of ß-glucan intake at a lower dose (0.5%) on reproduction. However, higher intake (1.5%) could perturb normal reproductive function in a fish model and caused an increased number of atretic follicles leading to spawning/reproductive failure.

Long- and short-term dietary ß-glucan improves intestinal health and disease resistance in pearl gentian grouper (Epinephelus lanceolatus♂ × Epinephelus fuscoguttatus♀).

ß-Glucans are immunostimulants and are widely used in aquaculture industry. The present study was conducted to evaluate the effects of different periods of ß-glucan management on growth performance, intestinal health, and disease resistance in pearl gentian grouper (Epinephelus lanceolatus♂ × Epinephelus fuscoguttatus♀). A commercial feed was used as control diet (CD), and the ß-glucan diet (ßD) was based on CD and further supplemented with 0.1% ß-glucan. Grouper in control and long-term ß-glucan diet (LGD) groups were fed with CD and ßD for 8 weeks, respectively. Groupers in short-term ß-glucan diet (SGD) group were fed with CD for the first 4 weeks and ßD for the last 4 weeks. We found that LGD and SGD had no effect on growth performance but reduced the mortalities of grouper after challenging with Vibrio harveyi. In addition, both LGD and SGD increased intestinal morphology, enhanced antioxidant capacity, enhanced immunity, inhibited apoptosis, altered the transcriptional profile, and activated mitogen-activated protein kinase (MAPK) and nuclear factor kappa-B (NF-κB) signaling pathway in the intestine of grouper. Furthermore, the effect of LGD on most of the above parameters was comparable to that of SGD. In conclusion, LGD and SGD did not affect growth rate parameters but enhanced the intestinal health and disease resistance of pearl gentian grouper.