Administration Of Β-glucan Research Articles

β-glucan mitigation on toxicological effects in monocytes/macrophages of Nile tilapia (Oreochromis niloticus) following copper exposure

The protective effect of β-glucan against toxicological effects caused by copper oxide nanoparticles (Cu NPs) and copper ions (Cu ions) were studied in monocytes/macrophages (MO/MФ) of Nile tilapia (Oreochromis niloticus). Our results demonstrated that CuO NPs and Cu ions exposure aroused strong oxidative lesion in MO/MФ by detection of cellular reactive oxygen species (ROS) and reduced glutathione (GSH), as well as identification of several antioxidant-related cytokines. Meanwhile, the serious pro-inflammatory responses were accompanied during the processes of oxidative lesion by TNFα, IL-1β, and IL-6 genes validation. Copper induced MO/MФ underwent apoptosis through mitochondrial signaling pathway by mitochondrial membrane potential (ΔΨm) detection and Bax, Bcl-2, Cyt-c, Apaf-1, Caspase 9, Caspase 3 genes validation. Furthermore, the phagocytic abilities were inhibition in MO/MФ by evaluation of microspheres (0.5 and 1.0 μm beads) and bioparticles (S. agalactiae and A. hydrophila) uptake and LPS-induced NO production. However, β-glucan might participate in immunomodulation through C-type lectin receptor (CLR) and complement receptor 3 (CR3) to suppress pro-inflammatory responses, thereby revered all the copper induced aforementioned adverse effects in MO/MΦ. Taken together, our results provide insights on the mechanisms through β-glucan administration to mitigate toxicological effects of CuO NPs and Cu ions exposure to the MO/MΦ, which will benefit aspects related to fish farming and aquaculture production.

Impact of Prebiotic β-glucan Treatment at Juvenile Age on the Gut Microbiota Composition and the Eventual Type 1 Diabetes Onset in Non-obese Diabetic Mice.

Complex dietary polysaccharides such as β-glucans are widely used for their anti-inflammatory properties. We reported before that oral administration of Yeast β-glucan (YBG) in adult mice can help delay type 1 diabetes (T1D) onset and suppress gut inflammation through modulation of the structure and function of gut microbiota. Since juvenile age is characterized by profoundly changing immature gut microbiota, we examined the impact of oral treatment with YBG in non-obese diabetic (NOD) mice at this age. Juvenile mice that received daily oral administration of YBG starting at 15 days of age for 7 or 30 days were examined for changes in gut microbiota, immune characteristics, and T1D incidence. Mice that received YBG for 30 days but not 7 days, showed considerable changes in the composition and diversity of fecal microbiota as compared to controls. Predictive functional analysis, based on 16S rDNA sequences, revealed overrepresentation of glycan biosynthesis and metabolism, energy metabolism, and fatty acid biosynthesis pathways in mice that received YBG for 30 days. Immune phenotype of the colon showed skewing toward immune regulatory and Th17 cytokines with increases in IL-10, IL-17, and IL-21 and a decrease in TNF-α, although increases in some pro-inflammatory cytokines (IL-1b, IFN-γ) were observed. Most importantly, mice that received YBG treatment for 30 days showed significantly suppressed insulitis and delayed onset of hyperglycemia compared to controls. Overall, this study suggests that oral consumption of YBG beginning at pre-diabetic juvenile ages could have positive maturational changes to gut microbiota and immune functions and could result in a delay in the disease onset in those who are pre-disposed to T1D.

Structural Studies of Water-Insoluble β-Glucan from Oat Bran and Its Effect on Improving Lipid Metabolism in Mice Fed High-Fat Diet.

Water-insoluble β-glucan has been reported to have beneficial effects on human health. However, no studies have thoroughly characterized the structure and function of water-insoluble β-glucan in oat bran. Thus, the structure and effect of water-insoluble β-glucan on weight gain and lipid metabolism in high-fat diet (HFD)-fed mice were analyzed. First, water-insoluble β-glucan was isolated and purified from oat bran. Compared with water-soluble β-glucan, water-insoluble β-glucan had higher DP3:DP4 molar ratio (2.12 and 1.67, respectively) and molecular weight (123,800 and 119,200 g/mol, respectively). Notably, water-insoluble β-glucan exhibited more fibrous sheet-like structure and greater swelling power than water-soluble β-glucan. Animal experiments have shown that oral administration of water-insoluble β-glucan tended to lower the final body weight of obese mice after 10 weeks treatment. In addition, water-insoluble β-glucan administration significantly improved the serum lipid profile (triglyceride, total cholesterol, high-density lipoprotein cholesterol, and low-density lipoprotein cholesterol levels) and epididymal adipocytes size. What is more, water-insoluble β-glucan reduced the accumulation and accelerated the decomposition of lipid in liver. In conclusion, water-insoluble β-glucan (oat bran) could alleviate obesity in HFD-fed mice by improving blood lipid level and accelerating the decomposition of lipid.

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.

Circadian disruption-induced metabolic syndrome in mice is ameliorated by oat β-glucan mediated by gut microbiota

Circadian disruption-induced metabolic syndrome (CDIMS) involves body weight gain, changes in blood profile and gut microbiota. In this study, CDIMS was induced by shifted light dark cycle (SLDC) in C57BL/6J mice. Dietary intervention by oral administration of oat β-glucan (a polymeric prebiotic) alleviated CDIMS when compared to chicory inulin/fructan (an oligomeric prebiotic) and melatonin (a chronobiotic). Oat β-glucan reversed the increase in body weight, liver weight-to-body weight ratio and plasma leptin concentration as well as restored glucose tolerance. In altering gut microbiota, oat β-glucan increased the species richness, reversed the populations of 7 bacterial genera and increased butyrate producers including Ruminococcaceae and Lachnospiraceae which enhance gut barrier protection and regulate glucose homeostasis. Correlation analysis demonstrated the linking of the alleviation of CDIMS by prebiotics and melatonin with different microbial metabolic pathways involved in energy metabolism, biosynthesis of metabolites, metabolism of cofactors and vitamins and endocrine synthesis.

Biological Effects of β-Glucans on Osteoclastogenesis.

Although the anti-tumor and anti-infective properties of β-glucans have been well-discussed, their role in bone metabolism has not been reviewed so far. This review discusses the biological effects of β-glucans on bone metabolisms, especially on bone-resorbing osteoclasts, which are differentiated from hematopoietic precursors. Multiple immunoreceptors that can recognize β-glucans were reported to be expressed in osteoclast precursors. Coordinated co-stimulatory signals mediated by these immunoreceptors are important for the regulation of osteoclastogenesis and bone remodeling. Curdlan from the bacterium Alcaligenes faecalis negatively regulates osteoclast differentiation in vitro by affecting both the osteoclast precursors and osteoclast-supporting cells. We also showed that laminarin, lichenan, and glucan from baker’s yeast, as well as β-1,3-glucan from Euglema gracilisas, inhibit the osteoclast formation in bone marrow cells. Consistent with these findings, systemic and local administration of β-glucan derived from Aureobasidium pullulans and Saccharomyces cerevisiae suppressed bone resorption in vivo. However, zymosan derived from S. cerevisiae stimulated the bone resorption activity and is widely used to induce arthritis in animal models. Additional research concerning the relationship between the molecular structure of β-glucan and its effect on osteoclastic bone resorption will be beneficial for the development of novel treatment strategies for bone-related diseases.

β‐glucan therapy converts the inhibition of myeloid‐derived suppressor cells in oral cancer patients

The myeloid-derived suppressor cells (MDSCs) frequently have a high expansion in cancer patients. This research explored whether administration of β-glucan could increase anti-tumor immunity in oral squamous cell carcinoma (OSCC) patients. This study evaluated the MDSC level of circulating blood as CD33+ /CD11b+ /HLA-DR-/low by flow cytometry in 30 healthy donors (HDs, group I), in 48 oral squamous cell carcinoma (OSCC) patients before and after 14-day preoperative administration of β-glucan (group II), and in 52 OSCC patients without taking β-glucan (group III). A significantly higher mean MDSC level was observed in 100 OSCC patients than in 30 HDs (p<.001). There was a significant reduction of the mean MDSC level in group II patients after taking β-glucan (p<.001). Moreover, we discovered a significantly higher recurrence-free survival (RFS) in group II than in group III patients (p=.026). Finally, the multivariate Cox regression further identified the MDSC level ≤1% and administration of β-glucan as more favorable prognostic factors for OSCC patients. Preoperative administration of β-glucan can augment anti-tumor immunity and increase RFS rate via subversion of suppressive function of MDSC in OSCC patients.

Fungal beta-glucans as adjuvants for treating cancer patients – A systematic review of clinical trials

Fungal β-glucans have been considered as biological response modifiers (BRMs) promoting stimulation of immune system according to numerous scientific publications performed invitro and invivo. Some clinical trials involving such compounds started to be published since 1980's. This systematic review aimed to compile and compare clinical studies using these β-glucans as adjuvants on patients undergoing cancer treatment. Healthy subjects and β-glucans from other sources were excluded. It was developed according to PRISMA-P guidelines (PROSPERO registered n. CRD42020151539), using PICO criteria and the following databases: PubMed, Scielo and LILACS. We found 1018 articles and after removing duplicated records, select by title/abstract and full-text, only 9 studies remained and 7 more were manually added, totalizing 16 trials involving 1650 patients, with arm sizes varying from 9 until 200 patients. The selected studies (published since 1992-2018) included subjects with diagnosis of 9 types of cancer. The studies used different sources of β-glucans, such as yeast (Saccharomyces cerevisiae), mushrooms (Lentinula edodes and Schizophyllum commune) and non-described fungal sources. It was observed that the administration of β-glucan is safe and well-tolerated. Most of the trials pointed that concomitant administration of β-glucan with chemo or radiotherapy reduced the immune depression caused by such treatments and/or accelerated the recovery of white blood cells counts. However, some articles also commented that no statistical difference was encountered between β-glucan treated vs. control groups, which gives a controversial conclusion about the β-glucan effects. The great diversity among the methodology studies and insufficient information was an impeditive for achieving profound statistical analysis, therefore a narrative report of the included studies was performed indicating that further evidences are required to determine the efficacy of this adjuvant in the cancer treatment.

Development of Fish Immunity and the Role of β-Glucan in Immune Responses.

Administration of β-glucans through various routes, including immersion, dietary inclusion, or injection, have been found to stimulate various facets of immune responses, such as resistance to infections and resistance to environmental stress. β-Glucans used as an immunomodulatory food supplement have been found beneficial in eliciting immunity in commercial aquaculture. Despite extensive research involving more than 3000 published studies, knowledge of the receptors involved in recognition of β-glucans, their downstream signaling, and overall mechanisms of action is still lacking. The aim of this review is to summarize and discuss what is currently known about of the use of β-glucans in fish.

β-Glucan improved the immunity, hepato-renal, and histopathology disorders induced by chlorpyrifos in Nile tilapia

This study aimed at investigating the potential role of β-glucan in improving the immunity, anti-inflammatory and histopathology disorders induced by chlorpyrifos in Nile tilapia. Fish were allocated in four group where the control fed the basal diet without chlorpyrifos toxicity and chlorpyrifos group fed the basal diet and subjected to chlorpyrifos (15 μg/L water). The third group fed dietary β-glucan (1 g/kg diet) without chlorpyrifos toxicity and the fourth group fed dietary β-glucan and exposed to chlorpyrifos (β-glucan/chlorpyrifos). Results revealed that the exposure to chlorpyrifos tended to decrease final body weight (FBW), weight gain (WG), specific growth rate (SGR), and survival but increased the feed intake (FI) and feed conversion ratio (FCR). Administration of β-glucan tended to increase FBW, WG, SGR, survival, and FI but did not change the FCR. Exposure to chlorpyrifos did not change the blood alkaline phosphatase (ALP) but increased aspartate aminotransferase (AST), alkaline phosphatase (ALP), and cortisol levels whereas β-glucan administration markedly decreased ALP, AST, ALT, and cortisol levels and β-glucan/chlorpyrifos treatment declined the levels of these variable close to the baseline values. Compared to the control, chlorpyrifos administration tended to decrease the lysozyme and phagocytic index but no change was observed in phagocytic activity. β-Glucan administration greatly increased the levels of lysozyme, phagocytic activity and phagocytic index, and β-glucan tended to alleviate the negative effect of chlorpyrifos on the mentioned parameters. The chlorpyrifos exposure caused congestion and telangiectasia in gills, catarrhal enteritis followed by degeneration and sloughing of the apical part of the intestinal villi with diffused lymphocytic infiltration, and fatty degeneration and vacuolation of hepatocytes in addition to congestion of blood sinusoids in liver. However, the histopathological structure of these organs was normal with dietary β-glucan. In conclusion, β-glucan administration alleviated the adverse effects of chlorpyrifos on the immune and anti-inflammatory response as well as histopathology of gills, liver, and intestine of Nile tilapia.

β-Glucan as Trained Immunity-Based Adjuvants for Rabies Vaccines in Dogs.

The mechanisms of trained immunity have been extensively described in vitro and the beneficial effects are starting to be deciphered in in vivo settings. Prototypical compounds inducing trained immunity, such as β-glucans, act through epigenetic reprogramming and metabolic changes of innate immune cells. The recent advances in this field have opened new areas for the development of Trained immunity-based adjuvants (TIbAs). In this study, we assessed in dogs the potential immune training effects of β-glucans as well as their capacity to enhance the adaptive immune response of an inactivated rabies vaccine (Rabisin®). Injection of β-glucan from Euglena gracilis was performed 1 month before vaccination with Rabisin® supplemented or not with the same β-glucan used as adjuvant. Trained innate immunity parameters were assessed during the first month of the trial. The second phase of the study was focused on the ability of β-glucan to enhance adaptive immune responses measured by multiple immunological parameters. B and T-cell specific responses were monitored to evaluate the immunogenicity of the rabies vaccine adjuvanted with β-glucan or not. Our preliminary results support that adjuvantation of Rabisin® vaccine with β-glucan elicit a higher B-lymphocyte immune response, the prevailing factor of protection against rabies. β-glucan also tend to stimulate the T cell response as shown by the cytokine secretion profile of PBMCs re-stimulated ex vivo. Our data are providing new insights on the impact of trained immunity on the adaptive immune response to vaccines in dogs. The administration of β-glucan, 1 month before or simultaneously to Rabisin® vaccination give promising results for the generation of new TIbA candidates and their potential to provide increased immunogenicity of specific vaccines.

Novel Antihypertension Mechanism of β-Glucan by Corin and ANP-Mediated Natriuresis in Mice

Many of the β-glucans are known to have antihypertensive activities, but, except for angiotensin-converting enzyme II inhibition, the underlying mechanisms remain unclear. Corin is an atrial natriuretic peptide (ANP)-converting enzyme. Activated corin cleaves pro-ANP to ANP, which regulates water–sodium balance and lowers blood pressure. Here, we reported a novel antihypertensive mechanism of β-glucans, involved with corin and ANP in mice. We showed that multiple oral administrations of β-glucan induced the expression of corin and ANP, and also increased natriuresis in mice. Microarray analysis showed that corin gene expression was only upregulated in mice liver by multiple, not single, oral administrations of the β-glucan fraction of Phellinus baumii (BGF). Corin was induced in liver and kidney tissues by the β-glucans from zymosan and barley, as well as by BGF. In addition to P. baumii, β-glucans from two other mushrooms, Phellinus linteus and Ganoderma lucidum, also induced corin mRNA expression in mouse liver. ELISA immunoassays showed that ANP production was increased in liver tissue by all the β-glucans tested, but not in the heart and kidney. Urinary sodium excretion was significantly increased by treatment with β-glucans in the order of BGF, zymosan, and barley, both in 1% normal and 10% high-sodium diets. In conclusion, we found that the oral administration of β-glucans could induce corin expression, ANP production, and sodium excretion in mice. Our findings will be helpful for investigations of β-glucans in corin and ANP-related fields, including blood pressure, salt–water balance, and circulation.

β-glucan administration improves growth performance and gut health in New Zealand White and APRI rabbits with different breed responses.

This study investigated the effects of oral administration of β-glucan 1,3 (pharmaceutical grade 10%) on growth performance and carcass traits in two breeds of weanling rabbits adapted to survive in Egypt, New Zealand White (NZW) and Animal Production Research Institute (APRI) rabbits, with special attention to relative mRNA expression of interleukins and antioxidant enzyme genes, biochemical, and histological alterations. Oral administration of β-glucan with doses 0.25 and 0.5 ml per one-liter of drinking water significantly accelerated body weight gain (BWG) in both rabbits’ breeds, reduced total feed consumption (FC), and reduced feed conversion ratio (FCR), especially the 0.5 ml per one-liter dose in both rabbit breeds. There are remarkable differences in all the growth performance traits due to breed effect. The interaction effect between β-glucan and breed significantly improved BWG, FC, and FCR. There were non-significant differences in all carcass traits studied due to oral administration of β-glucan with both doses, except in dressing percentages. The highest of the dressing percentages were observed at doses 0.25 ml per one-liter (51%) and 0.5 ml per one-liter (52%) compared with control (50%). Our findings show significant variations in the final BW, total daily gain, feed consumption, and total feed conversion ratio between NZW and APRI rabbits. Absence of significant differences in the hot carcass weight and dressing percentage between the genetic groups had been reported in this study. Supplementing NZW and APRI rabbits with β-glucan increased blood total protein and globulin. The duodenal villi dimensions, splenic lymphoid diameter, muscular fiber diameter, and muscular glycogen areas were significantly increased by β-glucan administration. Expression of intestinal interleukin-18 (IL-18) in NZW rabbits treated with 0.25 and 0.5 doses of β-glucan was significantly upregulated and enhanced the immune response. β-glucan upregulated the expression of intestinal occludin mRNA particularly at dose 0.5 β-glucan as well as upregulated intestinal superoxide dismutase 1 (SOD1) and glutathione peroxidase 1 (GPx1), which modulates anti-inflammatory and antioxidant properties. In conclusion, oral administration of β-glucan at a dose of 0.25 or 0.5 ml per one-liter drinking water provided beneficial effects in the growth performance and health status of rabbits.

Effect of β-glucan in water on growth performance, blood status and intestinal microbiota in tilapia under hypoxia

In the present study, the effects of β-glucan administration in water on growth performance and blood status (hematological indexes, immunological and biochemical parameters) were evaluated in Nile tilapia fingerlings (Oreochromis niloticus) under hypoxia-induced stress. In parallel, effect of this prebiotic (beta-glucan) was evaluated on gut microbiota diversity (16S rRNA gene) under normal oxygenation condition. Three treatments were implemented according to beta-glucan water supplementation: 0 (control), 0.1 and 0.3 mg L−1. Blood was collected before hypoxic challenge (BHC) and 9 h after hypoxic challenge (AHC). No significant differences were observed according to growh performance parameters. A significant increase in erythrocyte number and decrease in mean corpuscular volume (P < 0.05) were identified in control group when were under hypoxia. The plasma glucose level was higher in the 0.3 group than in the 0.1 group BHC; however, for all groups, the glucose level increased markedly AHC, and then receded seven days AHC (7AHC, P < 0.05). Total protein, serum lysozyme, plasma lactate, triglyceride, and cholesterol concentrations did not differ between groups. Comparison of the two β-glucan concentrations indicated that the 0.3 mg L−1 concentration promoted an increase in lymphocyte count. The 0.1 group showed the highest survival rate 7 days after hypoxia. Metagenomic analysis revealed a greater number of operational taxonomic units (OTUs) in the 0.1 and 0.3 groups. The Chao richness value was higher in the 0.1 group than in the control group (P < 0.05), with a greater abundance observed for members of the Vibrionaceae family. It is concluded that the concentration of 0.1 mg L−1 was able to increase tolerance to hypoxia, increasing the survival rate and regulating glucose levels. The concentration of 0.3 mg L−1 modulated hematological responses under stress and increased the lymphocyte count before hypoxic challenge.

β-Glucan Induces Protective Trained Immunity against Mycobacterium tuberculosis Infection: A Key Role for IL-1

Summaryβ-glucan is a potent inducer of epigenetic and functional reprogramming of innate immune cells, a process called “trained immunity,” resulting in an enhanced host response against secondary infections. We investigate whether β-glucan exposure confers protection against pulmonary Mycobacterium tuberculosis (Mtb) infection. β-glucan induces trained immunity via histone modifications at gene promoters in human monocytes, which is accompanied by the enhanced production of proinflammatory cytokines upon secondary Mtb challenge and inhibition of Mtb growth. Mice treated with β-glucan are significantly protected against pulmonary Mtb infection, which is associated with the expansion of hematopoietic stem and progenitor cells in the bone marrow and increased myelopoiesis. The protective signature of β-glucan is mediated via IL-1 signaling, as β-glucan shows no protection in mice lacking a functional IL-1 receptor (IL1R−/−). The administration of β-glucan may be used as a novel strategy in the treatment of mycobacterial infections and possibly as an adjuvant to improve anti-tuberculosis vaccines.

The preventable efficacy of β-glucan against leptospirosis.

Leptospirosis, caused by pathogenic Leptospira species, has emerged as an important neglected zoonotic disease. Few studies have reported the preventable effects of immunoregulators, except for antibiotics, against leptospirosis. Generally, immunostimulatory agents are considered effective for enhancing innate immune responses. Many studies have found that beta-glucan (β-glucan) could be a potent and valuable immunostimulant for improving immune responses and controlling diseases. In this study, we investigated the preventable role of β-glucan against Leptospira infection in hamsters. First, β-glucan was administered 24 h prior to, during and after infection. The results showed that β-glucan increased the survival rate to 100%, alleviated tissue injury, and decreased leptospire loads in target organs. Additionally, we found using quantitative real-time PCR that application of β-glucan significantly enhanced the expression of Toll-like receptor (TLR) 2, interleukin (IL)-1β and iNOS at 2 dpi (days post infection) and reduced the increase of TLR2, IL-1β and iNOS induced by Leptospira at 5 dpi. Furthermore, to induce memory immunity, β-glucan was administered 5 days prior to infection. β-Glucan also significantly increased the survival rates and ameliorated pathological damage to organs. Moreover, we demonstrated that β-glucan-trained macrophages exhibited elevated expression of proinflammatory cytokines (IL-1β and IL-6) in vitro, indicating that β-glucan induces an enhanced inflammatory response against Leptospira infection. These results indicate that administration of β-glucan and other immunostimulants could be potential valuable options for the control of Leptospira infection.

In vivo administration of LPS and β-glucan generates the expression of a serum lectin and its cellular receptor in Cherax quadricarinatus

In crustaceans, it has been suggested that specific protection against pathogens could be triggered by vaccines and biological response modifiers; although the specific mechanisms of this protection have not been clarified yet. In the crayfish Cherax quadricarinatus, a humoral lectin (CqL) binds its own granular hemocytes through a specific receptor (CqLR) and increases the production of reactive oxygen species (ROS). In the present study, we challenged in vivo crayfishes with immunostimulants, β-glucan (200 μg/kg) or LPS (20 μg/kg), and identified the participation of cellular and humoral mechanisms. The stimulants generated a complex modification in the total hemocytes count (THC), as well as in the proportion of hemocyte subsets. At 2 h after the challenge, the largest value in THC was observed in either challenged crayfishes. Furthermore, at the same time, hyaline hemocytes were the most abundant subset in the hemolymph; after 6 h, granular hemocytes (GH) were the most abundant hemocyte subset. It has been observed that a specific subset of GH possesses a CqLR that has been related to ROS production. After 2 and 6 h of the β-glucan challenge, a significant increase in CqLR expression was observed in the three circulating hemocyte subsets; also, an increased expression of CqL was detected in a granular hemocytes sub-population. After 2 and 6 h of stimulation, the specific activity of the serum lectin challenged with β-glucan was 250% and 160% higher than in the LPS-treated-group, respectively (P < 0.05). Hemocytes from challenged crayfishes were stimulated ex vivo with CqL, ROS production was 180% higher in hemocytes treated with β-glucan + CqL than in hemocytes treated with LPS + CqL (P < 0.05). The results evidence the effectivity of immune stimulators to activate specific crayfish defense mechanisms, the participation of CqL and its receptor (CqLR) could play an important role in the regulation of immune cellular functions, like ROS production, in Cherax quadricarinatus.

Hypolipidemic effects of barley-β-glucan in experimentally induced hyperlipidemic rats

Hyperlipidemia is one of the major risk factors for heart disease. One way to reduce the risk of developing the disease is to lower serum cholesterol levels by making dietary changes. Beta-glucan are glucose polymers present in cereal grains as barley,consumption of the whole grain or concentrated β-glucan preparation has been shown to lower blood lipid profile and atherogenic ratios. Fifty male albino rats were assigned into five groups. The control groupreceived standard diet, the hyperlipidemic group fed 1% cholesterol and 20% coconut oil in the dietfor 8 weeks. The β-glucan treated group received high fat diet for 4 weeks then high fat diet plus barley β-glucan 10 mg/rats given orally for more 4 weeks. The β-glucan protected group received standard diet +10 mg/rat barley β-glucan for 2 weeks then high fat diet + barley β-glucan 10 mg/rat for another 8 weeks. The β-glucan group received standard diet + barley β-glucan 10 mg/rat for 8 weeks. The hyperlipidemicrats showed an increase in lipid profile, total lipid, phospholipids, atherogenic ratios, liver enzymes, kidney functions and glucose and a decrease in HDL-C and albumin compared with the control group. Moreover histological examination of liver tissue of hyperlipidemic rats showed fatty hepatocytes compared with the control. Administration of barley β-glucan 10 mg/rat in treated and protected groups ameliorated the levels of lipids, atherogenic ratios, liver functions, kidney functions and glucose. In addition, the liver tissues showed improved pathological alterations.

Hematoprotective effects and antioxidant properties of β-glucan and vitamin C against acetaminophen-induced toxicity: an experimental study in rats

Acetaminophen is widely used as an over-the-counter analgesic and antipyretic drug. The aim of the present study was to investigate the pro-oxidative effects of acetaminophen (300 mg/kg/day i.p.) and antioxidative effects of β-glucan (4 mg/kg/day i.p.) and/or vitamin C (100 mg/kg/day i.p.) on the blood parameters of treated rats. After 3 days of treatment, hematological and parameters of redox status were measured. Exposure of rats to acetaminophen caused significant changes in some hematological parameters and the glutathione redox cycle, leading to an increased concentration of oxidative stress parameters and the formation of lipid peroxidation, while the activities of antioxidant enzymes were decreased. Administration of β-glucan and/or vitamin C reduced lipid peroxidation and restored the levels of examined hematological and oxidative stress parameters and improved the activities of antioxidant enzymes. Obtained results demonstrated that acetaminophen has significant pro-oxidative effects and may disrupt redox balance in blood of rats, while the combination of β-glucan and/or vitamin C amplified the antioxidant defense potential and exhibited a strong hematoprotective activity against acetaminophen-induced toxicity. Therefore, β-glucan and vitamin C co-treatment may be a promising therapeutic option for the treatment of acute acetaminophen hematotoxicity.

Discontinuous Administration of β-glucan is Effective for Preventing Immune Fatigue in Litopenaeus vannamei

β-glucan is an effective, available immunostimulant that has been successfully used to improve the immune defense of shrimp against pathogenic infection. However, the long-term continuous use of β-glucan can lead to immune fatigue, and intermittent feeding may be an effective way of avoiding this phenomenon. A 60-day growth trial was conducted to compare the effects of different feeding strategies of diets containing 200 mg/kg β-glucan on the growth and immune system of the Pacific white shrimp Litopenaeus vannamei. The results showed that either continuous feeding or intermittent feeding of diets containing 200 mg/kg β-glucan did not promote the growth of L. vannamei. However, the levels of superoxide dismutase, alkaline phosphatase, and acid phosphatase in the hepatopancreas of L. vannamei in the intermittent feeding group were significantly higher than those in the control and continuous feeding groups. Expression levels of the genes encoding LPS/β-glucan binding protein, superoxide dismutase, lysozyme, penaeid in-3a, and catalase were also significantly upregulated in the intermittent feeding group, whereas most of the immune parameters in the continuous feeding group were not significantly different from those of the control group. After artificial infection with Vibrio parahaemolyticus, the average mortality rates in the control group, the continuous feeding group, and the intermittent feeding group were 76.67%, 78.89%, and 45.56%, respectively. The results indicated that the addition of 200 mg/kg β-glucan to the diet did not promote the growth of L. vannamei, but the strategy of intermittent feeding effectively prevented immune fatigue and enhanced disease resistance, perhaps by increasing nonspecific immunity in L. vannamei.