Supplementation of the diet with Salecan attenuates the symptoms of colitis induced by dextran sulphate sodium in mice

Iron chelation and supplementation: A comparison in the management of inflammatory bowel disease using drosophila

AIMS

Inflammatory Bowel Disease (IBD) is associated with systemic iron deficiency and has been managed with iron supplements which cause adverse side effects. Conversely, some reports highlight iron depletion to ameliorate IBD. The underlying intestinal response and comparative benefit of iron depletion and supplementation in IBD is unknown. The aims of this work were to characterize and compare the effects of iron supplementation and iron depletion in IBD.

MAIN METHODS

IBD was induced in Drosophila melanogaster using 3 % dextran sodium sulfate (DSS) in diet for 7 days. Using this model, we investigated the impacts of acute iron depletion (using bathophenanthroline disulfonate, BPS) and supplementation (using ferrous sulphate, FS), before and after IBD induction, on gut iron homeostasis, cell death, gut permeability, inflammation, antioxidant defence, antimicrobial response and several fly phenotypes.

KEY FINDINGS

DSS decreased fly mass (p < 0.001), increased gut permeability (p < 0.001) and shortened lifespan (p = 0.035) compared to control. The DSS-fed flies also showed significantly elevated lipid peroxidation (p < 0.001), and the upregulated expression of apoptotic marker- drice (p < 0.001), tight junction protein - bbg (p < 0.001), antimicrobial peptide - dpta (p = 0.002) and proinflammatory cytokine - upd2 (p < 0.001). BPS significantly (p < 0.05) increased fly mass and lifespan, decreased gut permeability, decreased lipid peroxidation and decreased levels of drice, bbg, dpta and upd2 in IBD flies. This iron chelation (using BPS) showed better protection from DSS-induced IBD than iron supplementation (using FS). Preventive and curative interventions, by BPS or FS, also differed in outcomes.

SIGNIFICANCE

This may inform precise management strategies aimed at tackling IBD and its recurrence.

Salecan confers anti-inflammatory effects in liver injury via regulating gut microbiota and its metabolites

Salecan, a natural β-glucan and one of the novel food ingredients approved in China, has been shown a variety of positive health effects, yet the mechanism of liver injury remains poorly understood. In addition, β-glucan could induce the shifts in gut microbiota, however, whether modulation of gut microbiota by β-glucan is associated with their positive health effects remain elusive. Here, the anti-inflammatory effects and the underlying mechanism of Salecan supplementation in CCl4-induced liver injury were investigated. After 8 weeks of treatment, we observed that Salecan alleviated liver injury by regulating inflammatory response and M2 macrophage polarization. In addition, Salecan treatment modulated the composition of gut microbiota and antibiotic cocktail treatment indicated that the hepatoprotective effect of Salecan was dependent on the gut microbiota. Fecal microbiota transplantation was used to further verify the mechanism, and we confirmed that microbial colonization partially alleviated liver injury. Besides, microbiota-derived metabolites of Salecan also contributed to the hepatoprotective and anti-inflammatory effect of Salecan against liver injury. These findings supported that Salecan intervention attenuated liver injury by regulating gut microbiota and its metabolites.

Salecan ameliorates liver injury by regulating gut microbiota and its metabolites

Salecan ameliorates liver injury by regulating oxidative stress and the gut microbiota.

A water-soluble β-glucan improves growth performance by altering gut microbiome and health in weaned pigs

Beta-glucan has been shown to have a beneficial effect on gastrointestinal health. This experiment was conducted to investigate the effects of β-glucan isolated from Agrobacterium sp. ZX09 on growth performance and intestinal health of weaning pigs. A total of 108 weaned pigs (21 d of age; 6.05 ± 0.36 kg) were randomly divided into 3 groups (6 pens/group; 6 pigs/pen), and the groups were each treated with the following diets: 1) basal diet, 2) basal diet supplemented with 20 mg/kg olaquindox, 3) basal diet supplemented with 200 mg/kg β-glucan, for 21 d. Compared with the control group, pigs fed with 200 mg/kg β-glucan had greaterBW, average daily gain and duodenal villus height to crypt depth ratio (P < 0.05). Olaquindox increased the duodenal or jejunal villus height of pigs compared with β-glucan. Compared with the control group, β-glucan tended to increase the occludin mRNA expression in the jejunum (0.05 < P < 0.10). Beta-glucan enriched the beneficial microbiota in the ileum of pigs (P < 0.05). In conclusion, β-glucan may promote growth performance by improving intestinal health and increasing beneficial microbiota of weaned pigs. The study results will provide valuable theoretical guidance for the utilization of β-glucan in weaned pigs.

Dietary Curdlan Enhances Bifidobacteria and Reduces Intestinal Inflammation in Mice

β-glucan consumption is known for its beneficial health effects, but the mode of action is unclear. While humans and mice lack the required enzymes to digest β-glucans, certain intestinal microbes can digest β-glucans, triggering gut microbial changes. Curdlan, a particulate β-glucan isolated from Alcaligenes faecalis, is used as a food additive. In this study we determined the effect of curdlan intake in mice on the intestinal microbiota and dextran sodium sulfate (DSS)-induced intestinal inflammation. The effect of curdlan on the human intestinal microbiota was assessed using i-screen, an assay for studying anaerobic microbial interactions. Mice received oral gavage with vehicle or curdlan for 14 days followed by DSS for 7 days. The curdlan-fed group showed reduced weight loss and colonic inflammation compared to the vehicle-fed group. Curdlan intake did not induce general microbiota community changes, although a specific Bifidobacterium, closely related to Bifidobacterium choerinum, was observed to be 10- to 100-fold more prevalent in the curdlan-fed group under control and colitis conditions, respectively. When tested in i-screen, curdlan induced a global change in the microbial composition of the healthy intestinal microbiota from a human. Overall, these results suggest that dietary curdlan induces microbiota changes that could reduce intestinal inflammation.

Pretreatment with Yeast-Derived Complex Dietary Polysaccharides Suppresses Gut Inflammation, Alters the Microbiota Composition, and Increases Immune Regulatory Short-Chain Fatty Acid Production in C57BL/6 Mice

BACKGROUND

β-Glucans (BGs), a group of complex dietary polysaccharides (CDPs), are available as dietary supplements. However, the effects of orally administered highly purified BGs on gut inflammation are largely unknown.

OBJECTIVES

The aim of this study was to investigate the impact of orally administering highly purified, yeast-derived BG (YBG; β-1,3/1,6-d-glucan) on susceptibility to colitis.

METHODS

Eight-week-old C57BL/6 (B6) mice were used in a series of experiments. Experiment (Expt) 1: male and female mice were treated every day, for 40 d, with saline (control) or 250 μg YBG, followed by 2.5% (wt:vol) dextran sulfate sodium (DSS) in drinking water during days 30-35; and colitis severity and intestinal immune phenotype were determined. Expt 2: female B6 mice were treated with saline or YBG for 30 d and intestinal immune phenotype, gut microbiota composition, and fecal SCFA concentrations were determined. Expt 3: female B6 mice were treated as in Expt 2, given drinking water with or without antibiotics [Abx; ampicillin (1 g/L), vancomycin (0.5 g/L), neomycin (1 g/L), and metronidazole (1 g/L)] during days 16-30, and gut immune phenotype and fecal SCFA concentrations were determined. Expt 4: female B6 Foxp3-green fluorescent protein (-GFP) reporter mice were treated as in Expt 3, and intestinal T-regulatory cell (Treg) frequencies and immune phenotypes were determined. Expt 5: female mice were treated as in Expt 1, given drinking water with or without antibiotics during days 16-40, and colitis severity and intestinal cytokine production were determined.

RESULTS

Compared with controls, the YBG group in Expt 1 exhibited suppressive effects on features of colitis, such as loss of body weight (by 47%; P < 0.001), shortening of colon (by 24%; P = 0.016), and histopathology severity score (by 45%; P = 0.01). The YBG group of Expt 2 showed a shift in the abundance of gut microbiota towards Bacteroides (by 16%; P = 0.049) and Verrucomicrobia (mean ± SD: control = 7.8 ± 0.44 vs. YBG = 21.0 ± 9.6%) and a reduction in Firmicutes (by 66%; P < 0.001). The YBG group also showed significantly higher concentrations of fecal SCFAs such as acetic (by 37%; P = 0.016), propionic (by 47%; P = 0.026), and butyric (by 57%; P = 0.013) acids. Compared with controls, the YBG group of Expt 2 showed higher frequencies of Tregs (by 32%; P = 0.043) in the gut mucosa. Depletion of gut microbiota in the YBG group of mice caused diminished fecal SCFA concentrations (Expt 3) and intestinal Treg frequencies (Expt 4). Compared with the YBG group, the YBG-(Abx) group of Expt 5 showed aggravated colitis features including loss of body weight (by >100%; P < 0.01) and colonic inflammation score (by 42%; P = 0.04).

CONCLUSIONS

Studies using B6 mice show that dietary BGs are beneficial for promoting intestinal health when the gut microbiota is intact. However, these CDPs may produce adverse effects if gut microbiota is compromised.

Dietary leonurine hydrochloride supplementation attenuates lipopolysaccharide challenge-induced intestinal inflammation and barrier dysfunction by inhibiting the NF-κB/MAPK signaling pathway in broilers

This study was performed to evaluate the beneficial effects of dietary leonurine hydrochloride (LH) supplementation on intestinal morphology and barrier integrity and further illuminate its underlying antioxidant and immunomodulatory mechanisms in lipopolysaccharide (LPS)-treated broilers. A total of 120 1-d-old male broilers (Ross 308) were assigned to 4 treatment groups with 6 replicates of 5 birds per cage. The experiment was designed in a 2 × 2 factorial arrangement with LH (0 or 120 mg/kg) and LPS (injection of saline or 1.5 mg/kg body weight) as treatments. On days 14, 16, 18, and 20 of the trial, broilers were intraperitoneally injected with LPS or physiological saline. Compared with the control group, LPS-challenged broilers showed impaired growth performance (P < 0.05) from day 15 to day 21 of the trial, increased serum diamine oxidase (DAO) and D-lactic acid (D-LA) levels coupled with reduced glutathione (GSH) content and total superoxide dismutase (T-SOD) activity (duodenal and jejunal mucosa), reduced malondialdehyde (MDA) content (duodenal, jejunal, and ileal mucosa), and compromised morphological structure of the duodenum and jejunum. Additionally, LPS challenge increased (P < 0.05) the mRNA expression of proinflammatory cytokine genes and reduced tight junction (TJ) protein expression in the jejunum. However, dietary LH prevented LPS-induced reductions in average daily gain (ADG) and average daily feed intake (ADFI) in broilers. It also alleviated LPS challenge-induced increases in serum DAO levels, MDA content (duodenal and jejunal mucosa), and jejunal crypt depth (P < 0.05) but reduced villus height, GSH content (jejunal mucosa), and T-SOD activity (duodenal and jejunal mucosa) (P < 0.05). Additionally, LH supplementation significantly downregulated the mRNA expression of nuclear factor (NF)-κB, cyclooxygenase-2 (COX-2), and proinflammatory cytokines (TNF-α, IL-1β, and IL-6) and upregulated the mRNA expression of zonula occludens-1 (ZO-1) and Occludin in the jejunal mucosa induced by LPS (P < 0.05). On the other hand, LH administration prevented LPS-induced activation of the p38, extracellular signal-regulated kinase (ERK) and c-Jun N-terminal kinase (JNK) mitogen-activated protein kinases (MAPKs) and attenuated IkB alpha (IκBα) phosphorylation and nuclear translocation of NF-κB (p65) in the jejunal mucosa. In conclusion, dietary LH supplementation attenuates intestinal mucosal disruption mainly by accelerating the expression of TJ proteins and inhibiting activation of the NF-κB/MAPK signaling pathway.

Synthesis and Evaluation of Oligomeric Thioether-Linked Carbacyclic β-(1→3)-Glucan Mimetics

Extrapolating from lessons learnt with previous low-molecular-weight β-(1→3)-glucan mimetics, we designed a series of minimal 2,4-dideoxy-thioether-linked carbacyclic β-(1→3)-glucan mimetics and synthesized di-, tri-, and tetramers in an enantiomerically pure form by an iterative sequence based on a simple building block readily available from commercial ( S)-(-)-3-cyclohexenecarboxylic acid. These substances were screened for their ability to inhibit anti-CR3-fluorescein isothiocyanate (FITC) staining of human neutrophils and anti-Dectin-1-FITC staining of mouse macrophages as well as for their ability to stimulate phagocytosis and pinocytosis. In each assay, the synthetic compounds displayed comparable activity to the corresponding native β-(1→3)-glucans, laminaritriose, and tetraose, suggesting that the exploitation of hydrophobic patches in the lectin-binding domains of CR3 and Dectin-1 is a promising strategy for the development of small-molecule analogues of β-(1→3)-glucans.

Trained Innate Immunity and Its Implications for Mucosal Immunity and Inflammation

The long-standing dogma that immunological memory is the exclusive prerogative of the adaptive immune system has been challenged by emerging evidence that innate immunity can also maintain memory of past events. Such immunological imprinting takes two forms, trained innate immunity and tolerance. Trained immunity involves metabolic and epigenetic adaptations in innate immune cells and their progenitors in the bone marrow upon exposure to certain microbial and/or inflammatory stimuli so that the "trained" cells would be poised to respond much faster and stronger to a subsequent challenge (e.g., a new infection that is not necessarily the same as the earlier one). Conversely, tolerance leads to attenuated immune responses to secondary stimuli. This review focuses on trained immunity and discusses evidence for its existence from lower organisms to humans, its mechanistic underpinnings, and its translational ramifications. Although trained immunity can be considered as an evolutionarily conserved beneficial response against reinfections, in the setting of modern societies with high prevalence of chronic mucosal and systemic inflammatory diseases, trained immunity could also promote maladaptive immune responses that aggravate pathology. Thus, depending on context, innate immune memory could be therapeutically manipulated using defined agonists to either promote innate immune responses (particularly useful for the treatment of infections or chemotherapy-induced myelosuppression) or suppress excessive inflammation in inflammatory and autoimmune diseases.

Synthesis and Evaluation of 1,5-Dithia-d-laminaribiose, Triose, and Tetraose as Truncated β-(1→3)-Glucan Mimetics

The preparation and characterization of a series of di-, tri-, and tetrasaccharide analogues of β-(1→3)-glucans is described in which each pyranoside ring is replaced by a 5-thiopyranosyl ring and each glycosidic oxygen by a thioether. These oligomeric 1,5-dithio-d-glucopyranose derivatives were shown to inhibit the staining of human neutrophils and of mouse macrophages by fluorescent anti-CR3 and anti-Dectin-1 antibodies, respectively. The compounds were also demonstrated to stimulate phagocytosis and pinocytosis indicative of binding to the carbohydrate binding domains of complement receptor 3 (CR3) and Dectin-1. Activity in all three assays was optimum at the level of the trisaccharide mimic, suggesting that, while the replacement of ethereal oxygens by thioethers results in a greater affinity for the aromatic lined hydrophobic binding pockets, the presence of multiple longer C-S bonds eventually results in a mismatch and a loss of affinity.

β-glucan Salecan Improves Exercise Performance and Displays Anti-Fatigue Effects through Regulating Energy Metabolism and Oxidative Stress in Mice

Fatigue induced by prolonged exercise not only leads to the decrease of exercise capacity, but also might be the cause of many diseases. In consideration of the side effects of pharmacological drugs, dietary supplements seem to be a better choice to ameliorate exercise-induced fatigue. The present study aimed to investigate the anti-fatigue effect of Salecan, a novel water-soluble β-glucan, during exercise and explore the underlying mechanisms. Male Institute of Cancer Research (ICR) mice were divided into five groups, including the Rest group and the other four Swim-groups treated with Salecan at 0, 25, 50, and 100 mg/kg/day for four weeks. Salecan treatment markedly increased the exhaustive swimming time of mice in the forced swimming test. Exercise fatigue and injury-related biochemical biomarkers including lactate, blood urea nitrogen (BUN), creatinine kinase (CK), alanine transaminase (ALT), and aspartate transaminase (AST) were ameliorated by Salecan. Salecan reversed the decreased serum glucose levels and glycogen contents caused by exercise. In addition, Salecan improved oxidative stress induced by exercise through regulating Nrf2/HO–1/Trx signaling pathway. Thus, the beneficial effects of Salecan against fatigue may be due to its positive effects on energy metabolism and antioxidation defence. Our results suggest that Salecan could be a novel potential candidate for anti-fatigue dietary supplements.

Rosmarinus officinalis L. extract ameliorates intestinal inflammation through MAPKs/NF-κB signaling in a murine model of acute experimental colitis

We investigated the anti-inflammatory and anti-colitis effects of Rosmarinus officinalis L. extract (RE) by using both in vitro LPS-activated mouse RAW 264.7 macrophages and in vivo dextran sulfate sodium (DSS)-induced experimental murine colitis and suggested the underlying possible mechanisms. Liquid Chromatography-Mass Spectrometry (LC-MS) analysis was performed to identify the major components present in the RE. The clinical signs, biochemistry, immunoblot, ELISA and histology in colon tissues were assessed in order to elucidate the beneficial effect of RE. RE suppressed the LPS-induced pro-inflammatory cytokine production and the expressions of inflammatory proteins in macrophages. Administration of RE (50 and 100 mg kg(-1)) also significantly reduced the severity of DSS-induced murine colitis, as assessed by the clinical symptoms, colon length and histology. RE administration prevented the DSS-induced activation of p38, ERK and JNK MAPKs, attenuated IκBα phosphorylation and subsequent nuclear translocation and DNA binding of NF-κB (p65). RE also suppressed the COX-2 and iNOS expressions, decreased the levels of TNF-α and IL-6 cytokines and the myeloperoxidase activity in the colon tissue. Histological observation revealed that RE administration alleviated mucosal damage and inflammatory cell infiltration induced by DSS in the colon tissue. Hence, RE could be used as a new preventive and therapeutic food ingredient or as a dietary supplement for inflammatory bowel disease.

Salecan protected against concanavalin A-induced acute liver injury by modulating T cell immune responses and NMR-based metabolic profiles

Salecan, a water-soluble extracellular β-glucan produced by Agrobacterium sp. ZX09, has been reported to exhibit a wide range of biological effects. The aims of the present study were to investigate the protective effect of salecan against Concanavalin A (ConA)-induced hepatitis, a well-established animal model of immune-mediated liver injury, and to search for possible mechanisms. C57BL/6 mice were pretreated with salecan followed by ConA injection. Salecan treatment significantly reduced ConA-induced acute liver injury, and suppressed the expression and secretion of inflammatory cytokines including interferon (IFN)-γ, interleukin (IL)-6 and IL-1β in ConA-induced liver injury model. The high expression levels of chemokines and adhesion molecules such as MIP-1α, MIP-1β, ICAM-1, MCP-1 and RANTES in the liver induced by ConA were also down-regulated after salecan treatment. Salecan inhibited the infiltration and activation of inflammatory cells, especially T cells, in the liver induced by ConA. Moreover, salecan reversed the metabolic profiles of ConA-treated mice towards the control group by partly recovering the metabolic perturbations induced by ConA. Our results suggest the preventive and therapeutic potential of salecan in immune-mediated hepatitis.

Smart Macroporous Salecan/Poly(N,N-diethylacrylamide) Semi-IPN Hydrogel for Anti-Inflammatory Drug Delivery

Poly(N,N-diethylacrylamide) is not only a thermosensitive polymer, but also a good hydrogen bond acceptor. Therefore, drugs with carboxyl groups can serve as hydrogen bond donors and form interactions with the tertiary amide groups in N,N-diethylacrylamide. Herein, we report a novel drug delivery system for anionic drugs composed of poly(N,N-diethylacrylamide) and salecan. Salecan was used to improve the hydrophilicity and accelerate the responsive rate of this system. As expected, salecan-enriched hydrogels exhibited higher swelling ratios and were more sensitive to temperature. Moreover, scanning electron microscopy images showed that the hydrogels are superporous structures, with pore-sizes that increase with salecan concentration. The swelling ratios decreased continuously with the increase of temperature in the range 25-37 °C. MTT assay for cell viability and cell adhesion studies confirm the cell compatibility of the system. Delivery tests using diclofenac sodium, an anti-inflammatory drug, indicate that the thermosensitive property of this system is favorable for anionic drug delivery. Interestingly, the release rates of diclofenac sodium from the hydrogels were temperature dependent, with higher temperatures contributing toward faster release rate.

Salecan Enhances the Activities of β-1,3-Glucanase and Decreases the Biomass of Soil-Borne Fungi

Salecan, a linear extracellular polysaccharide consisting of β-1,3-D-glucan, has potential applications in the food, pharmaceutical and cosmetic industries. The objective of this study was to evaluate the effects of salecan on soil microbial communities in a vegetable patch. Compositional shifts in the genetic structure of indigenous soil bacterial and fungal communities were monitored using culture-dependent dilution plating, culture-independent PCR-denaturing gradient gel electrophoresis (DGGE) and quantitative PCR. After 60 days, soil microorganism counts showed no significant variation in bacterial density and a marked decrease in the numbers of fungi. The DGGE profiles revealed that salecan changed the composition of the microbial community in soil by increasing the amount of Bacillus strains and decreasing the amount of Fusarium strains. Quantitative PCR confirmed that the populations of the soil-borne fungi Fusarium oxysporum and Trichoderma spp. were decreased approximately 6- and 2-fold, respectively, in soil containing salecan. This decrease in the amount of fungi can be explained by salecan inducing an increase in the activities of β-1,3-glucanase in the soil. These results suggest the promising application of salecan for biological control of pathogens of soil-borne fungi.