Co-evolution of the humoral immune and serotonergic systems in chickens selected for high or low blood antibody titer response to sheep red blood cells

Serotonin is a potent immunomodulatory neurohormone. Activities of the serotonergic and immune systems are often reported together in poultry studies with unidirectional analyses focused on serotonergic signaling mediating immune response. Considering serotonin's relevance across a range of immune-related poultry topics, elucidation of whether the immune system affects the serotonergic system can provide valuable insights into the bi-directionality of poultry neuroendocrine-immune interactions. The present study sought to determine whether selection for divergence in blood antibody titers to a non-pathogenic antigen coincides with parallel changes in the chicken's serotonergic system over the life of the bird. We utilized generations 49 and 50 male and female White Leghorn chickens (n = 10-12/chickens/line/sex/age) that have been selected long-term for high (HAS) or low (LAS) blood antibody response to intravenous sheep red blood cell injection. Because serotonin is predominantly produced in the gut and acts as an interkingdom signaling molecule, the first experiment sampled cecal tissue and luminal content samples from male and female HAS and LAS chickens at 293 days of age. In the second experiment, cecal tissue and luminal content, as well as plasma, were collected from HAS and LAS chickens at 28 and 56 days of age. Serotonin and its main metabolite, 5-hydroxyindoleacetic acid (5-HIAA), concentrations were determined in cecal tissue, luminal content, and plasma samples. Immunoglobulins IgA and IgY concentrations were analyzed in cecal luminal content or plasma, respectively. The HAS chickens had lower (p < 0.05) cecal IgA concentrations but higher (p < 0.05) plasma IgY concentrations than LAS chickens, suggesting a compensatory response within the intestinal tract following selection for high or low blood antibody titers. Serotonin and 5-HIAA concentrations in the ceca and plasma diverged (p < 0.05) in a pattern that mirrored ceca IgA and plasma IgY differences according to genetic line. The results from this study demonstrate that evolutionary selection pressure for humoral immune response in chickens causes responses in the serotonergic system at both enteric and systemic levels.

Preventing bacterial disease in poultry in the post-antibiotic era: a case for innate immunity modulation as an alternative to antibiotic use

The widespread use of antibiotics in the poultry industry has led to the emergence of antibiotic-resistant bacteria, which pose a significant health risk to humans and animals. These public health concerns, which have led to legislation limiting antibiotic use in animals, drive the need to find alternative strategies for controlling and treating bacterial infections. Modulation of the avian innate immune system using immunostimulatory compounds provides a promising solution to enhance poultry immune responses to a broad range of bacterial infections without the risk of generating antibiotic resistance. An array of immunomodulatory compounds have been investigated for their impact on poultry performance and immune responses. However, further research is required to identify compounds capable of controlling bacterial infections without detrimentally affecting bird performance. It is also crucial to determine the safety and effectiveness of these compounds in conjunction with poultry vaccines. This review provides an overview of the various immune modulators known to enhance innate immunity against avian bacterial pathogens in chickens, and describes the mechanisms involved.

Efficacy of a Synergistic Blend of Organic Acids and ß-1,4 Mannobiose on Cecal Salmonella Counts and Growth Performance in Salmonella Challenged Broiler Chickens: A Meta-Analysis

This study aimed at investigating the effect of a functional synergistic feed additive blend, containing organic acids and ß-1,4 mannobiose, on cecal Salmonella counts and growth performance of broiler chickens. A meta-analysis combining 13 individual studies, executed in Salmonella-challenged broilers comparing a control diet with and without the synergistic blend, was performed. Cecal Salmonella colonies and overall growth performance were measured. Raw data from all studies were combined and analyzed using PROC MIXED in SAS, taking the within and between-study variation into account. In the first 14 days post-inoculation (DPI), cecal Salmonella was reduced by 0.429 log CFU/g (p = 0.011, n = 10 comparisons from five studies) when feeding the synergistic blend compared to the control group. During 15-34 DPI, the overall means were not different between treatments (0.069 log CFU/g; p = 0.519, n = 12 comparisons from eight studies). The feed conversion ratio was improved when feeding the synergistic blend compared to the control diet (1.474 vs. 1.482, respectively; p = 0.002). In conclusion, feeding a synergistic blend, containing organic acids and ß-1,4 mannobiose amongst other ingredients, reduced cecal Salmonella counts during the first 14 DPI and improved growth performance of Salmonella challenged broilers compared to a control diet.

Prebiotics: A Potential Treatment Strategy for the Chemotherapy-damaged Gut?

Mucositis, characterized by ulcerative lesions along the alimentary tract, is a common consequence of many chemotherapy regimens. Chemotherapy negatively disrupts the intestinal microbiota, resulting in increased numbers of potentially pathogenic bacteria, such as Clostridia and Enterobacteriaceae, and decreased numbers of "beneficial" bacteria, such as Lactobacilli and Bifidobacteria. Agents capable of restoring homeostasis in the bowel microbiota could, therefore, be applicable to mucositis. Prebiotics are indigestible compounds, commonly oligosaccharides, that seek to reverse chemotherapy-induced intestinal dysbiosis through selective colonization of the intestinal microbiota by probiotic bacteria. In addition, evidence is emerging that certain prebiotics contribute to nutrient digestibility and absorption, modulate intestinal barrier function through effects on mucin expression, and also modify mucosal immune responses, possibly via inflammasome-mediated processes. This review examines the known mechanisms of prebiotic action, and explores their potential for reducing the severity of chemotherapy-induced mucositis in the intestine.

Dietary Mannan Oligosaccharides: Counteracting the Side Effects of Soybean Meal Oil Inclusion on European Sea Bass (Dicentrarchus labrax) Gut Health and Skin Mucosa Mucus Production?

The main objective of this study was to assess the effects of 4 g kg(-1) dietary mannan oligosaccharides (MOS) inclusion in soybean oil (SBO)- and fish oil (FO)-based diets on the gut health and skin mucosa mucus production of European sea bass juveniles after 8 weeks of feeding. Dietary MOS, regardless of the oil source, promoted growth. The intestinal somatic index was not affected, however dietary SBO reduced the intestinal fold length, while dietary MOS increased it. The dietary oil source fed produced changes on the posterior intestine fatty acid profiles irrespective of MOS dietary supplementation. SBO down-regulated the gene expression of TCRβ, COX2, IL-1β, TNFα, IL-8, IL-6, IL-10, TGFβ, and Ig and up-regulated MHCII. MOS supplementation up-regulated the expression of MHCI, CD4, COX2, TNFα, and Ig when included in FO-based diets. However, there was a minor up-regulating effect on these genes when MOS was supplemented in the SBO-based diet. Both dietary oil sources and MOS affected mean mucous cell areas within the posterior gut, however the addition of MOS to a SBO diet increased the mucous cell size over the values shown in FO fed fish. Dietary SBO also trends to reduce mucous cell density in the anterior gut relative to FO, suggesting a lower overall mucosal secretion. There are no effects of dietary oil or MOS in the skin mucosal patterns. Complete replacement of FO by SBO, modified the gut fatty acid profile, altered posterior gut-associated immune system (GALT)-related gene expression and gut mucous cells patterns, induced shorter intestinal folds and tended to reduce European sea bass growth. However, when combined with MOS, the harmful effects of SBO appear to be partially balanced by moderating the down-regulation of certain GALT-related genes involved in the functioning of gut mucous barrier and increasing posterior gut mucous cell diffusion rates, thus helping to preserve immune homeostasis. This denotes the importance of a balanced dietary n-3/n-6 ratio for an appropriate GALT-immune response against MOS in European sea bass juveniles.

Prebiotics and gut microbiota in chickens

Prebiotics are non-digestible feed ingredients that are metabolized by specific members of intestinal microbiota and provide health benefits for the host. Fermentable oligosaccharides are best known prebiotics that have received increasing attention in poultry production. They act through diverse mechanisms, such as providing nutrients, preventing pathogen adhesion to host cells, interacting with host immune systems and affecting gut morphological structure, all presumably through modulation of intestinal microbiota. Currently, fructooligosaccharides, inulin and mannanoligosaccharides have shown promising results while other prebiotic candidates such as xylooligosaccharides are still at an early development stage. Despite a growing body of evidence reporting health benefits of prebiotics in chickens, very limited studies have been conducted to directly link health improvements to prebiotic-dependent changes in the gut microbiota. This article visits the current knowledge of the chicken gastrointestinal microbiota and reviews most recent publications related to the roles played by prebiotics in modulation of the gut microbiota and immune functions. Progress in this field will help us better understand how the gut microbiota contributes to poultry health and productivity, and support the development of new prebiotic products as an alternative to in-feed antibiotics.

Anti-inflammatory effects of mannanase-hydrolyzed copra meal in a porcine model of colitis

We evaluated the anti-inflammatory activity of mannanase-hydrolyzed copra meal (MNB), including β-1,4-mannobiose (67.8%), in a dextran sodium sulfate (DSS)-induced porcine model of intestinal inflammation. In the DSS-positive control (POS) and MNB treatment (MCM) groups, DSS was first administered to piglets via intragastric catheter for 5 days, followed by 5 days administration of saline or MCM. A negative control group (NEG) received a saline alternative to DSS and MNB. Inflammation was assessed by clinical signs, morphological and histological measurements, gut permeability and neutrophil infiltration. Local production of TNF-α and IL-6 were analyzed by ELISA, colonic and ileal inflammatory gene expressions were assessed by real time RT-PCR, and CD4+CD25+ cell populations were analyzed by flow cytometry. Crypt elongation and muscle thickness, D-mannitol gut permeation, colonic expression of the inflammatory mediators TNF-α and IL-6 and myeloperoxidase activity were significantly lower in the MCM group than in that of POS group. The mRNA levels of ileal IL-1β, IL-6, IL-17 and TNF-α were significantly lower following MCM treatment than with POS treatment.MNB exerts anti-inflammatory activity in vivo, suggesting that MNB is a novel therapeutic that may provide relief to human and animals suffering from intestinal inflammation.

Comparison of gene expression profiles of the jejunum of broilers supplemented with a yeast cell wall-derived mannan oligosaccharide versus bacitractin methylene disalicylate

1. The addition of yeast cell wall (YCW) mannan fractions or low concentrations of antibiotics to the diet of broilers positively affects gut health by improving intestinal cell morphology and improves feed efficiency and performance; however the exact mechanisms are unclear. Based on these production responses, the objective of this study was to compare the effects of supplementing YCW and bacitracin methylene disalicylate (BMD) in the diet on mRNA levels in the jejunum of 6-week-old broilers. 2. Dietary treatments were a maize-soya control diet and the control diet with the addition of YCW or BMD. Birds (n = 7) from each dietary treatment were randomly selected and killed at d 42. Whole jejunum (with serosa) samples were collected for RNA isolation. Gene expression analysis was performed using the AffymetrixGeneChip Chicken Genome Array (Santa Clara, CA, USA). 3. Supplementation with YCW resulted in 928 genes that were significantly changed (456 down-regulated, 472 up-regulated) and supplementation with BMD resulted in 857 genes that significantly changed (408 down-regulated, 449 up-regulated). In addition, 316 genes were significantly changed by both YCW and BMD (146 down-regulated, 170 up-regulated). 4. BMD increased the expression of genes involved in lipid and carbohydrate metabolism and decreased expression of genes associated with T-helper cell pathways. Gene expression profiles from birds fed on diets containing YCW showed changes on a genomic level that correspond to slower gut cell turnover and therefore increased energy preservation for growth. 5. In conclusion, supplementation with BMD or YCW had similar influences on the number of differentially expressed genes in the jejunum. Biological functions common to both YCW and BMD with positive activation scores included antiviral response and antimicrobial response. Genes that were affected by BMD or YCW classified into both different and common biological functions and pathways related to improved metabolism and health in the jejunum.

Effect of dietary mannanase-hydrolysed copra meal on growth performance and intestinal histology in broiler chickens

We investigated mannanase-hydrolysed copra meal (MCM), which contains β-1,4-mannobiose (MNB), for its capacity to improve growth performance and activate intestinal villus function. Seven-day-old chicks were separated into four flocks with an equal mean body weight and then fed a basal diet (control) or a diet supplemented with 0.02% or 0.1% MCM. After 7 weeks, the feed intake and body weight were determined and then used to calculate the feed efficiency (FE). Moreover, the intestinal segments were examined by light microscopy and scanning electron microscopy (SEM) for cellular and morphological changes in the villus. Although feed intake was not significantly different among the experimental groups, the body weight gain and FE were significantly higher in the 0.1% MCM group than in the control group (p < 0.05), while feed intake tended to be higher in the 0.02% and 0.1% MCM groups. The cellular area of the ileum was significantly higher in the 0.02% and 0.1% groups in relation to that in the control group (p < 0.05). Furthermore, the cellular area of the duodenum and the jejunum tended to be higher in the 0.02% and 0.1% MCM groups. For the correlation analysis, a significant correlation was observed between the dosage of MCM and the cell area of the duodenum, jejunum and ileum. Moreover, the number of mitotic cells was higher in the 0.1% MCM group. As shown by SEM, the cells at the villi tips were protuberant in appearance in the 0.02% and 0.1% MCM treatments when compared with the relatively flat cells of the control. On the duodenal villus surface of the 0.1% MCM group, some cells devoid of microvilli were observed, suggesting that the increased protuberance of these cells represents increased absorption activity. Although intestinal villus height and area did not significantly differ among groups, the levels of these parameters tended to increase in the experimental groups relative to the control. The present morphological findings reveal that MNB might be effective for activating intestinal absorptive function, and that the functional activation promotes the growth of the chickens.

Newly Developed Synbiotics and the Chemotherapy-Damaged Gut

Mucositis is a common side-effect of cancer chemotherapy and radiotherapy. Features of mucositis include erythema, ulceration, and inflammation of the gastrointestinal tract accompanied by clinical symptoms of abdominal pain and digestive disturbances. New treatment strategies are required. Experimental evidence is accumulating showing therapeutic promise for new nutraceutical agents including probiotic bacteria, probiotic-derived factors, prebiotics, and plant extracts. However, the targeted development of new combinations of these agents (synbiotics) to combat mucositis remains largely unexplored. The current review addresses the potential for these nutraceutical agents to reduce the severity of chemotherapy-damaged mucositis by strategically aligning their underlying mechanism of action with features of mucositis pathogenesis. The potential for certain plant extracts to act as prebiotics, in combination with probiotics or their derived factors, is further investigated. These unique synbiotic formulations could form the basis of a new naturally sourced adjunctive approach to cancer chemotherapy.

Therapeutic effects of β1, 4 mannobiose in a Balb/c mouse model of intranasally-induced pollen allergy

BACKGROUND

Nutritional prebiotic supplementation represents an attractive approach for interventions of allergy. In this study, the potential therapeutic effect of β-1, 4 mannobiose (MNB) in a murine model of cedar pollinosis was investigated.

METHODS

Groups of Balb/c mice were intranasally sensitized to Japanese cedar pollen extract, and subsequently administered with low or high dose MNB. Both intraperitoneal and intranasal challenges were performed to monitor for clinical signs. Frequency of sneezing was recorded. Serum, spleen and Peyer's patches were collected for various biomarker analyses. Anti-allergic activity of MNB using RBL-2H3 cells was also evaluated.

RESULTS

Significant decrease in sneezing frequency, histamine, interleukin (IL)-4 and IL-17A and increase in TGF-β and IL-10 concentration were exhibited by the MNB-treated mice. However, Cry j1 and Cry j 2-specific IgE activity remained unaltered. The high dose MNB treatment increased total IgA activity and IL-10, TGF-β and FoxP3 and decreased IL-4, IL-17A, and RORγT mRNA expression. Inhibition of activation of RBL-2H3 cells was observed via decrease in histamine, intracellular Ca2+ concentration, and FcεRI mRNA expression.

CONCLUSIONS

We demonstrated the immunomodulatory effects of MNB and conclude that MNB is a potential therapeutic molecular nutritional supplement candidate for treatment of pollen allergy.

Prophylaxis of intranasally induced pollen allergy in a BALB/C mouse model using a potential prebiotic β-1, 4 mannobiose

BACKGROUND

Dietary supplementation with unique prebiotic nondigestible carbohydrates has been shown to suppress allergy. In the present study, the prophylactic efficacy of a disaccharide β-1, 4 mannobiose (MNB) in a BALB/C mouse model of intranasally-induced pollen allergy was characterized.

METHODS

Balb/c mice were pretreated with MNB orally and sensitized with pollen extract intraperitoneally and intranasally and challenged with histamine and crude pollen extract. Outcomes were measured as clinical signs, antibody isotypes, cytokine gene and protein expression patterns.

RESULTS

The MNB-treated mice had lower sneezing frequency as compared to the positive control mice (P < 0.05). The low dose MNB-treated mice had less histamine (P < 0.05). However, the Cry j1 and Cry j 2-specific IgE, IgG, IgG1 and IgG2a antibody activity did not differ between groups (P > 0.05). The MNB-treated mice had increased IFN-γ (P < 0.05), and decreased IL-4 (P < 0.05). Mice in the high dose group had increased IL-10 (P < 0.05). However, TGF-β and IL-17 concentration did not differ between groups (P > 0.05). Both total and Cry j1 and Cry j 2-specific IgA were increased in the high dose group. Real-time RT-PCR analysis indicated that IL-4 and IL-17 mRNA expression were lower in MNB-treated mice (P < 0.05).

CONCLUSIONS

This work provides insights into using MNB as a potential prebiotic immunomodulator via decreased clinical signs, improved type1/type 2 balance, and IgA production, thus validating the potential use of MNB as a prophylactic prebiotic candidate to attenuate allergic response.

β-1,4-mannobiose stimulates innate immune responses and induces TLR4-dependent activation of mouse macrophages but reduces severity of inflammation during endotoxemia in mice

β-1,4-Mannobiose (MNB) has been shown to exert prebiotic activity and modulate mucosal gene expression. In this study, the immune-modulating effect of MNB in healthy and endotoxemic mice and its role in Toll-like receptor (TLR) 2/4-mediated macrophage activation were investigated. Mice were supplemented daily with MNB (0, 5, 10, or 25 mg/kg) for 14 d. To examine the effect of MNB during endotoxemia, mice were supplemented with or without MNB (25 mg/kg) for 14 d, followed by challenge with intraperitoneal LPS or saline. MNB induced expression of both T helper (Th) 1- and Th2-type cytokines in the ileum (P < 0.05) and increased fecal IgA production and splenic NK cell activity (P < 0.05) in healthy mice. In endotoxemic mice, MNB reduced the expression of Tnfa, Il-6, iNos (P < 0.05), and Il-10 (P < 0.05), and reduced LPS-induced weight loss but increased Ifng, Il-12p40, Il-5, and Ifna expression (P < 0.05) and NK cell activity relative to positive control (LPS) mice. Treatment of RAW 264.7 macrophages with MNB induced TNF-α and IL-6 secretion (P < 0.05), and this effect was abrogated by inhibiting TLR4, but not TLR2, signaling. Pretreatment of RAW 264.7 cells with MNB induced tolerance to TLR2 and TLR4 agonists, reducing TNF-α production (P < 0.05) upon secondary stimulation with LPS or lipoteichoic acid. These results indicate that MNB can modulate intestinal and systemic immune responses in healthy and endotoxemic mice and prevent LPS-induced immune suppression, as well as directly stimulating innate immune mechanisms in vitro as a TLR4 agonist.

β 1-4 mannobiose enhances Salmonella-killing activity and activates innate immune responses in chicken macrophages

Salmonella spp. is one of the major causes of food-borne illness in humans, and Salmonella enteritidis (SE) infection in commercial poultry is a world-wide problem. Here we have investigated the in vitro immune-modulating effects of β 1-4 mannobiose (MNB), which was previously found to prevent SE infection in vivo in chickens, using chicken macrophage (MQ-MCSU) cells. Treatment of MQ-NCSU cells with MNB dose-dependently increased both phagocytic activity and Salmonella-killing activity of macrophages, with the highest reduction in SE viability observed at a concentration of 40 μg/ml at 48 h post-infection. Likewise, both hydrogen peroxide (H(2)O(2)) and nitric oxide (NO) production were increased in a dose-dependent manner by MNB. Gene expression analysis of MNB-treated macrophages revealed significant increases in the expression of iNOS, NOX-1, IFN-γ, NRAMP1, and LITAF, genes critical for host defense and antimicrobial activity, when compared to untreated cells. This data confirms that MNB possesses potent innate immune-modulating activities and can up-regulate antibacterial defenses in chicken macrophages.