Gut Mucosal Immune Responses Research Articles

Systemic exposure to bacterial amyloid curli alters the gut mucosal immune response and the microbiome, exacerbating Salmonella-induced arthritis

ABSTRACT The Salmonella biofilm-associated amyloid protein, curli, is a dominant instigator of systemic inflammation and autoimmune responses following Salmonella infection. Systemic curli injections or infection of mice with Salmonella Typhimurium induce the major features of reactive arthritis, an autoimmune disorder associated with Salmonella infection in humans. In this study, we investigated the link between inflammation and microbiota in exacerbating autoimmunity. We studied C57BL/6 mice from two sources, Taconic Farms and Jackson Labs. Mice from Taconic Farms have been reported to have higher basal levels of the inflammatory cytokine IL − 17 than do mice from Jackson Labs due to the differences in their microbiota. When we systemically injected mice with purified curli, we observed a significant increase in diversity in the microbiota of Jackson Labs mice but not in that of the Taconic mice. In Jackson Labs, mice, the most striking effect was the expansion of Prevotellaceae. Furthermore, there were increases in the relative abundance of the family Akkermansiaceae and decreases in families Clostridiaceae and Muribaculaceae in Jackson Labs mice. Curli treatment led to significantly aggravated immune responses in the Taconic mice compared to Jackson Labs counterparts. Expression and production of IL − 1β, a cytokine known to promote IL − 17 production, as well as expression of Tnfa increased in the gut mucosa of Taconic mice in the first 24 hours after curli injections, which correlated with significant increases in the number of neutrophils and macrophages in the mesenteric lymph nodes. A significant increase in the expression of Ccl3 in colon and cecum of Taconic mice injected with curli was detected. Taconic mice injected with curli also had elevated levels of inflammation in their knees. Overall, our data suggest that autoimmune responses to bacterial ligands, such as curli, are amplified in individuals with a microbiome that promote inflammation.

Specific activation of hypoxia-inducible factor-2α by propionate metabolism via a β-oxidation-like pathway stimulates MUC2 production in intestinal goblet cells

Microbiota-derived short-chain fatty acids (SCFAs) are known to stimulate mucin expression in the intestine, which contributes to the gut mucosal immune responses, and the gut mucosal immune system extends to the brain and other organs through several axes. Hypoxia-inducible factors (HIFs), especially HIF-1α, are known to act as the master regulator of mucin expression, however, underlying mechanism of mucin expression during hypoxia by SCFAs remains unclear. In this study, we investigated the mechanism of MUC2 expression by propionate, an SCFA, in intestinal goblet cells. The real time oxygen consumption rate (OCR) and ATPase activity were measured to investigate the induction of hypoxia by propionate. Using 2-dimensional electrophoresis (2-DE), microarray analysis, and siRNA-induced gene silencing, we found that propionate is metabolized via a β-oxidation-like pathway instead of the vitamin B12-dependent carboxylation pathway (also known as the methylmalonyl pathway). We verified the results by analyzing several intermediates in the pathway using LC-MS and GC-MS. Propionate metabolism via the β-oxidation-like pathway leads to the depletion of oxygen and thereby induces hypoxia. Analysis of HIFs revealed that HIF-2α is the primary HIF whose activation is induced by propionate metabolism in a hypoxic environment and that HIF-2α regulates the expression of MUC2. Thus, hypoxia induced during propionate metabolism via a β-oxidation-like pathway specifically activates HIF-2α, stimulating MUC2 production in LS 174 T goblet cells. Our findings show that propionate-induced selective HIF-2α stimulation contributes to intestinal mucosal defense.

Gut mucosal immune responses and protective efficacy of oral yeast Cyprinid herpesvirus 2 (CyHV-2) vaccine in Carassius auratus gibelio

Cyprinid herpesvirus 2 (CyHV-2) causes herpesviral hematopoietic necrosis (HVHN) disease outbreaks in farmed Cyprinid fish, which leads to serious economic losses worldwide. Although oral vaccination is considered the most suitable strategy for preventing infectious diseases in farmed fish, so far there is no commercial oral vaccine available for controlling HVNN in gibel carp (C. auratus gibelio). In the present study, we developed for the first time an oral vaccine against CyHV-2 by using yeast cell surface display technology and then investigated the effect of this vaccine in gibel carp. Furthermore, the protective efficacy was evaluated by comparing the immune response of a single vaccination with that of a booster vaccination (booster-vaccinated once 2 weeks after the initial vaccination). Critically, the activities of immune-related enzymes and genes expression in vaccine group, especially in the booster vaccine group, were higher than those in the control group. Moreover, strong innate and adaptive immune responses could be elicited in both mucosal and systemic tissues after receipt of the oral yeast vaccine. To further understand the protective efficacy of this vaccine in gibel carp, we successfully developed the challenge model with CyHV-2. Our results showed the relative percent survival was 66.7% in the booster vaccine group, indicating this oral yeast vaccine is a promising vaccine for controlling CyHV-2 disease in gibel carp aquaculture.

Experimental colonization with Blastocystis ST4 is associated with protective immune responses and modulation of gut microbiome in a DSS-induced colitis mouse model

BackgroundBlastocystis is a common gut protistan parasite in humans and animals worldwide, but its interrelationship with the host gut microbiota and mucosal immune responses remains poorly understood. Different murine models of Blastocystis colonization were used to examine the effect of a common Blastocystis subtype (ST4) on host gut microbial community and adaptive immune system.ResultsBlastocystis ST4-colonized normal healthy mice and Rag1−/− mice asymptomatically and was able to alter the microbial community composition, mainly leading to increases in the proportion of Clostridia vadinBB60 group and Lachnospiraceae NK4A136 group, respectively. Blastocystis ST4 colonization promoted T helper 2 (Th2) response defined by interleukin (IL)-5 and IL-13 cytokine production, and T regulatory (Treg) induction from colonic lamina propria in normal healthy mice. Additionally, we observed that Blastocystis ST4 colonization can maintain the stability of bacterial community composition and induce Th2 and Treg immune responses to promote faster recovery from experimentally induced colitis. Furthermore, fecal microbiota transplantation of Blastocystis ST4-altered gut microbiome to colitis mice reduced the severity of colitis, which was associated with increased production of short-chain fat acids (SCFAs) and anti-inflammatory cytokine IL-10.ConclusionsThe data confirm our hypothesis that Blastocystis ST4 is a beneficial commensal, and the beneficial effects of Blastocystis ST4 colonization is mediated through modulating of the host gut bacterial composition, SCFAs production, and Th2 and Treg responses in different murine colonization models.

A182 THE LACK OF CHROMOGRANIN A IMPACTS COLONIC EPITHELIAL CELLS MARKERS IN AN EXPERIMENTAL MODEL OF ULCERATIVE COLITIS

BackgroundUlcerative colitis (UC) is a chronic and acute inflammatory disorder of the colon linked to dysregulated gut mucosal immune response and compromised colonic epithelial barrier function and integrity. Chromogranin-A (CHGA), a pro-peptide secreted by enteroendocrine cells, is highly expressed in colonic tissues of patients with UC. Elevated CHGA has been shown to correlate with UC disease activity and severity. Moreover, complete deletion of CHGA was shown to result in a diminution of pro-inflammatory markers known to disrupt the colonic epithelial barrier function and gut mucosal healing process. However, little is known about the effect of the absence of CHGA on colonic epithelial barrier function and gut mucosal integrity.AimsHere, we characterized the impact of the lack of CHGA on the colonic mucosa and epithelial barrier structure and function using CHGA knockout (CHGA-/-) mice treated with dextran sulfate sodium (DSS) to induce colitis.Methods13–17 weeks old male C57BL/6 wild-type (CHGA+/+) and C57BL/6 CHGA-/- mice were treated for 5 days with 5% DSS to induced acute colitis, control mice received regular water. CHGA mRNA expression, disease activity index (DAI), and macroscopic score (MS) were analyzed. Distal colonic tissues were isolated, and mRNA expression of markers associated with regenerative stem cells (fast-cycling stem cells [Lgr5+] and reserve stem cells [HOPX+] and [LY6a+], Goblet cells functions mucus barrier mucin 2 [MUC2], resistin-like molecule β [RELMβ], WAP 4-disulphide core domain 2 [WFDC2]) and trefoil factor 3 (TFF3) was evaluated by qRT-PCR.ResultsWe validated a beneficial effect of the Lack of CHGA on colitis severity, associated with significantly lower DAI and MS. In colitic CHGA+/+ and CHGA-/- mice, Lgr5+ and HOPX+ were both highly down-regulated, although, compared to CHGA+/+, CHGA-/- mice presented a 10.5fold higher expression of HOPX+. Compared to non-colitic states, Ly6a+ expression was significantly elevated in both colitic CHGA+/+ and CHGA-/- mice, however, no differences in Lgr5+ and Ly6a+ expression were noted between CHGA+/+ and CHGA-/- mice in all conditions. In CHGA+/+ mice, inflammatory conditions led to higher MUC2 and RELMB expression, although, compared to CHGA+/+, these markers were significantly lower in CHGA-/- mice. In colitic conditions, compared to CHGA+/+, CHGA-/- had a significant increase of WFDC2. In non-colitic conditions, mRNA expressions of all markers evaluated between CHGA+/+ and CHGA-/- in this study were unaltered. Finally, no differences were observed in TFF3 gene expression.ConclusionsThese results indicate in the absence of CHGA, the colonic epithelial barrier integrity and function are maintained through the modulation of goblet cells functions and elevated gut mucosa regenerative potential, thus enhancing the mucosal protection to colitis damage.Funding AgenciesCIHR

Host-Viral Interactions in the Pathogenesis of Ulcerative Colitis.

Ulcerative colitis is characterized by relapsing and remitting colonic mucosal inflammation. During the early stages of viral infection, innate immune defenses are activated, leading to the rapid release of cytokines and the subsequent initiation of downstream responses including inflammation. Previously, intestinal viruses were thought to be either detrimental or neutral to the host. However, persisting viruses may have a role as resident commensals and confer protective immunity during inflammation. On the other hand, the dysregulation of gut mucosal immune responses to viruses can trigger excessive, pathogenic inflammation. The purpose of this review is to discuss virus-induced innate immune responses that are at play in ulcerative colitis.

Diet Rich in Simple Sugars Promotes Pro-Inflammatory Response via Gut Microbiota Alteration and TLR4 Signaling.

Diet is a strong modifier of microbiome and mucosal microenvironment in the gut. Recently, components of western-type diets have been associated with metabolic and immune diseases. Here, we studied how high-sugar diet (HSD) consumption influences gut mucosal barrier and immune response under steady state conditions and in a mouse model of acute colitis. We found that HSD significantly increased gut permeability, spleen weight, and neutrophil levels in spleens of healthy mice. Subsequent dextran sodium sulfate administration led to severe colitis. In colon, HSD significantly promoted neutrophil infiltration and increased the levels of IL-6, IL-1β, and TNF-α. Moreover, HSD-fed mice had significantly higher abundance of pathobionts, such as Escherichia coli and Candida, in fecal samples. Although germ-free mice colonized with microbiota of conventionally reared mice that consumed different diets had equally severe colitis, mice colonized with HSD microbiota showed markedly increased infiltration of neutrophils to the gut. The induction of colitis in Toll-like receptor 4 (TLR4)-deficient HSD-fed mice led to significantly milder colitis than in wild-type mice. In conclusion, our results suggested a significant role of HSD in disruption of barrier integrity and balanced mucosal and systemic immune response. In addition, these processes seemed to be highly influenced by resident potentially pathogenic microbiota or metabolites via the TLR4 signaling pathway.

Effects of probiotics on the enhancement of the innate mucosal immune response against pathogenic bacteria.

Background and Objectives:Probiotics have been widely used for host immune system enhancement but with limited knowledge regarding the immunomodulation mechanisms by which they assist the mucosal innate immune response. We investigated the effects of probiotics on the modulation of the innate mucosal immune response particularly in association with Toll-like receptor (TLR)-2, TLR-4 and nuclear factor-kappa B (NF-κB) p65 and p105.Materials and Methods:We randomized 24 male BALB/c mice into four groups. Two groups were administered probiotics for 21 consecutive days; one of these groups was challenged with Lipopolysaccharide (LPS) on day 15. The third group was challenged with only LPS. The fourth group remained untreated. All mice were sacrificed after 21 days. An immunohistochemistry procedure on the ileum was performed and monoclonal antibodies specific for TLR-2, TLR-4 and NF-κB p65 and p105 were used for the analysis of innate lymphoid cells.Results:In the LPS-only treated group, there was a significant decrease in p105, indicating an alternative transcription pathway for the process of pro-inflammatory cytokine production. In the probiotics-only treated group there was significant enhancement of TLR-2 and TLR-4 and NF-κB p65 and p105. When mice treated with probiotics were exposed to LPS, there was a significant decrease in NF-κB p65 and p105, indicating employment of the classical pathway for pro-inflammatory cytokine production.Conclusion:Probiotics can enhance the innate mucosal immune response in healthy mice and can maintain the homeostasis of the gut mucosal immune response against LPS through the activation of the classical NF-κB pathway.

Immunogenicity of Fusion Protein of Cholera Toxin B Subunit-Porphyromonas gingivalis 53-kDa Minor Fimbrial Protein Produced in Nicotiana benthamiana

Porphyromonas gingivalis induces destruction of periodontal tissues that surround and support the teeth, contributing to the development of periodontitis, which eventually results in tooth loss in adults. A 53-kDa protein of P. gingivalis is a major subunit variant protein of minor fimbriae (Mfa1), and is reported to be highly immunogenic and considered as a potential vaccine candidate. The gene encoding 53-kDa protein, was divided into three segments, and each DNA segment was fused to the gene coding for cholera toxin B subunit (CTB) to improve gut mucosal immune responses. The ctb-mfal fusion genes were expressed in the leaf tissues of Nicotiana benthamiana using agroinfiltration. Immunoblot analysis revealed that CTB-Mfa1 fusion proteins were produced in the agroinfiltrated leaves. The interaction of the plant-produced CTB-Mfa1 fusion proteins with GM1-ganglioside, which acts as the binding site for native CTB, was confirmed by GM1-ELISA. Mice immunized orally with the agroinfiltrated leaf powder containing the CTB-Mfa1 fusion proteins elicited serum IgG and fecal IgA antibodies to CTB and Mfa1. These results suggest that CTB-Mfa1 fusion proteins produced in plants can be used as an oral vaccine to control P. gingivalis infection-associated periodontitis.

A Demographic Profile of Inflammatory Bowel Disease in Uttar Karnataka

Inflammatory bowel disease (IBD) results from production of dysregulated gut mucosal immune response to luminal antigens. Scientific literature pertaining to Southern part of Indian is limited, especially with focus on demographic and clinical phenotypes of IBD. Hence, the present study is aimed at evaluating these factors in a geographic area of Uttar Karnataka in two types of IBD- Ulcerative colitis (UC) and Crohn’s disease (CD). Methodology: A retrospective study was done with 91 patients with IBD from 2009 to 2019. Patients were routinely started on treatment with local and systemic 5-aminosalicylic acid derivatives. Different line of therapies was administered to both UC and Crohn’s disease with different drugs or combination of drugs. Results: Of the 91 patients, 85 were having UC and 6 with CD. The mean age of patients with UC and CD was 41.8 years and 52.2 years; male predominance was observed in UC group of patients in contrast to CD group. UC patients were found with Extraintestinal manifestation i.e. Erythema nodosum (0.01%), Type 1 peripheral arthritis (0.01%), Type 2 peripheral arthritis (0.01%). A total of 6 UC patients required surgery for various causes, with the majority being males, including 2 of them who developed cancer. Conclusion: There was a predominance of patients with UC, especially in men. The age, origin and level of education may interfere with early diagnosis. This geographical region survey provides an opportunity for understanding possible etiopathogenetic factors associated with the disease and pattern of treatment.

4,4'-Diaponeurosporene-Producing Bacillus subtilis Promotes the Development of the Mucosal Immune System of the Piglet Gut.

Gut mucosal immune responses are known to act as the first line of defense against invasion of pathogenic microorganisms. Piglets have an incompletely developed gut mucosal immune system, making them sensitive to intestinal infections. Promoting the development of the mucosal immune system will increase the pathogen resistance of piglets. The aim of the present study was to investigate the effect of carotenoid (4,4'-diaponeurosporene)-producing Bacillus subtilis (B.s-Dia) on intestinal mucosal immunity in piglets. We showed that oral administration to piglets of B.s-Dia remarkably improved the development of Peyer's patches (PPs) (P < 0.01), and increased villus height (P < 0.01) and colon crypt depth (P < 0.01). In addition, B.s-Dia also increased the number of intraepithelial lymphocytes (P < 0.01), while Bacillus subtilis (B.s) had no significant influence on it (P > 0.05). Moreover, B.s-Dia also increased the number of SIgA+ cells (P < 0.01). Oral administration of either B.s or B.s-Dia increased the number of CD4+ and CD8+ cells in ileum lamina propria (P < 0.01). These results indicate that B.s-Dia contributes to a higher extent to porcine mucosal immune system development than B.s, and might serve as an immunopotentiator candidate. Anat Rec, 302:1800-1807, 2019. © 2019 American Association for Anatomy.

STING-Mediated Intestinal Barrier Dysfunction Contributes to Lethal Sepsis

Gut integrity is compromised in abdominal sepsis with increased cellular apoptosis and altered barrier permeability. Intestinal epithelial cells (IEC) form a physiochemical barrier that separates the intestinal lumen from the host's internal milieu and is strongly involved in the mucosal inflammatory response and immune response. Recent research indicates the involvement of the stimulator of interferons genes (STING) pathway in uncontrolled inflammation and gut mucosal immune response. We investigated the role of STING signaling in sepsis and intestinal barrier function using intestinal biopsies from human patients with abdominal sepsis and with an established model of abdominal sepsis in mice. In human abdominal sepsis, STING expression was elevated in peripheral blood mononuclear cells and intestinal biopsies compared with healthy controls, and the degree of STING expression in the human intestinal lamina propria correlated with the intestinal inflammation in septic patients. Moreover, elevated STING expression was associated with high levels of serum intestinal fatty acid binding protein that served as a marker of enterocyte damage. In mice, the intestinal STING signaling pathway was markedly activated following the induction of sepsis induced by cecal ligation perforation (CLP). STING knockout mice showed an alleviated inflammatory response, attenuated gut permeability, and decreased bacterial translocation. Whereas mice treated with a STING agonist (DMXAA) developed greater intestinal apoptosis and a more severe systemic inflammatory response. We also showed that blocking TNF or type I interferon signaling suppressed DMXAA-induced systemic shock and IEC apoptosis. In addition, we demonstrated that mitochondrial DNA (mtDNA) was released during sepsis, inducing the intestinal inflammatory response through activating the STING pathway. We finally investigated DNase I administration at 5 hours post CLP surgery, showing that it reduced systemic mtDNA and inflammatory cytokines levels, organ damage, and bacterial translocation, suggesting that inhibition of mtDNA-STING signaling pathway protects against CLP-induced intestinal barrier dysfunction. Our results indicate that the STING signaling pathway can contribute to lethal sepsis by promoting IEC apoptosis and through disrupting the intestinal barrier. Our findings suggest that regulation of the mtDNA-STING pathway may be a promising therapeutic strategy to promote mucosal healing and protect the intestinal barrier in septic patients. Funding Statement: This study was supported by National Natural Science Foundation of China (81571881, 81772052 and 81801971), and Medical Research Program of Jiangsu Commission of Health (H2018058). Declaration of Interests: We declare no potential conflicts of interest concerning the research, authorship, and/or publication of this article. Ethics Approval Statement: This study was carried out according to the Recommendations of Guidelines for Clinical Trials by the Ethics Committee of Jinling Hospital. All animal experiments in our study were carried out according to the principles of the Declaration of Helsinki, and were approved by the Animal Ethical Committee of Jinling Hospital. The protocol was approved by the Ethics Committee of Jinling Hospital. All patients provided written informed consent before any study-related procedure was performed.

Effect of enteral glutamine supplementation for low-birth-weight infants on weight gain patterns and levels of fecal secretory immunoglobulin A.

Glutamine is needed for optimal cell growth and for the immune system, especially in the enterocytes of gut mucosal immune responses. Low birth weight makes infants susceptible to glutamine depletion because nutrition is limited in the first week of life. To determine the effect of enteral glutamine supplementation on weight gain patterns and fecal secretory immunoglobulin A. This study is a double-blind, randomized controlled trial. Infants were randomly assigned to the glutamine group and placebo group. The glutamine group was supplemented with glutamine 400 mg/kg/day for 14 days, and placebo group received glucose 400 mg/kg/day for 14 days. The infants were observed for 30 days. Return-to-birth-weight, weight gain velocity, and fecal secretory immunoglobulin A levels were monitored during the study. Thirty-seven low-birth-weight infants were randomly assigned to the glutamine and placebo groups. The glutamine group had a shorter return-to-birth-weight time than the placebo group (8.1±0.9 vs. 11.0±1.6 days) and faster weight gain velocity (20.0±1.8 vs. 15.5±2.2 g/kg/day) (p<0.001). Secretory immunoglobulin A levels after glutamine supplementation were higher than in the placebo group (0.456±0.057 vs. 0.376±0.035 mg/g) (p<0.001). Levels of secretory immunoglobulin A after treatment in each group were increased. However, there was a significant difference before and after supplementation between the glutamine and placebo groups (0.247±0.024 vs. 0.140±0.016 mg/g) (p<0.001). Enteral glutamine supplementation in low-birth-weight infants accelerates return to birth weight, increases the weight gain velocity, and the levels of fecal secretory immunoglobulin A.

Effect of route of inoculation on innate and adaptive immune responses to porcine epidemic diarrhea virus infection in suckling pigs

The effects of route of administration on systemic and gut mucosal immune responses induced by porcine epidemic diarrhea virus (PEDV) infection in suckling pigs were investigated. Twenty-four conventional 5-day-old suckling piglets were randomly divided into four groups and were inoculated orally, intranasally (I.N.), intramuscularly (I.M.) with PEDV or DMEM (mock). Pigs were monitored daily for clinical signs and fecal viral load. Blood samples were collected at 7, 14, 21 days post infection (dpi) and subjected for the analyses of serum antibody production, T cell and natural killer (NK) cell frequencies, NK cytotoxicity and serum cytokine levels. Oral inoculation led to higher levels of PEDV-specific IgA antibodies in both serum and gut mucosal sites than did other routes of inoculation. Intranasal inoculation elicited significantly higher titers of virus-specific IgG antibodies in serum. PEDV-infected pigs regardless of inoculation routes had significantly lower NK cell frequencies than those of the control pigs at 14 dpi. The orally inoculated pigs had significantly higher CD3+CD8+ T cell frequencies as compared to I.N. or I.M. inoculated pigs at 14 dpi, while there was no significant difference among orally, I.N. or I.M. inoculated pigs and control pigs in CD3+CD4+ T cell frequencies in peripheral blood. PEDV-infected and control pigs had low, but detectable NK cell activities at 14 and 21 dpi, however, NK cell activities were barely detectable at 7 dpi whether the pigs were infected or not. Serum IL-10 levels were induced drastically in orally infected pigs at 7 dpi and then gradually declined. Serum IL-12 levels followed a similar pattern while the fold-change was much lower. In conclusion, oral inoculation may generate more comprehensive immune responses.

Two highly adhesive lactic acid bacteria strains are protective in zebrafish infected with Aeromonas hydrophila by evocation of gut mucosal immunity.

To increase the knowledge of probiotic effects and potential mechanisms, we report on the use of the zebrafish model to investigate the in vivo colonization ability, as well as the protective effects associated with gut mucosal immune barrier and responses against Aeromonas hydrophila infection of previously characterized probiotic lactic acid bacteria (LAB) strains, Bacillus coagulans 09·712 and Lactobacillus plantarum 08·923, in comparison with that of three commercialized strains. The results indicated differential adhesion capabilities, and B. coagulans and Lact. plantarum strains exhibited a more robust adhesion capability based on fluorescence observation. Oral delivery of these two strains in zebrafish greatly improved gut epithelium integrity, as well as reduced recruitment and degranulation of mast cells under Aer. hydrophila challenge. The percentage of intraepithelial lymphocytes (IELs) in probiotic fed groups was significantly higher than those in the control after challenge (P < 0·001). We also found that the abundance of IL-1β mRNA in B. coagulans- and Lact. plantarum-fed groups remarkably decreased as a function of time of post challenge, and that of TNF-α and IL-10 mRNA was high with the probiotic treatment. Our findings indicate highly adhesive strains of B. coagulans 09·712 and Lact. plantarum 08·923 have immunoregulatory and immunoprotective roles in effective stimulation of anti-inflammatory response and barrier regeneration within the mucosa to protect zebrafish against infection. Our work will further support zebrafish as a powerful model to better understand molecular definition of probiotic effects, as well as the probiotic potential of B. coagulans 09·712 and Lact. plantarum 08·923 of interest to the food industry.

Enhanced immune responses of chickens to oral vaccination against infectious bursal disease by ginseng stem-leaf saponins

Infectious bursal disease (IBD), caused by infectious bursal disease virus (IBDV), is an immunosuppressive infectious disease of global economic importance in poultry. This study was designed to evaluate the effect of oral administration of ginseng stem-leaf saponins (GSLS) on humoral and gut mucosal immunity in chickens vaccinated with live IBDV vaccine, and furthermore, to test its protective efficacy against virulent IBDV challenge following vaccination. In experiment 1, chickens were orally administered with GSLS at 5 mg/kg of BW for 7 d, and then immunized with live IBDV vaccine via the oral route. Serum was sampled on 0, 1, 2, 3, 4, and 5 wk postvaccination for detecting antibody titers by ELISA, and intestinal tissues were collected on 0, 1, 3, and 5 wk postvaccination for measurement of IgA-positive cells and intestinal intraepithelial lymphocytes by immunohistochemical and hematoxylin-eosin staining, respectively. Result showed that antibody titers, IgA-positive cells and intestinal intraepithelial lymphocytes were significantly higher in chickens drinking GSLS than the control, suggesting an enhanced effect of GSLS on humoral and gut mucosal immune responses. In experiment 2, chickens were delivered with GSLS and then vaccinated in the same way as in experiment 1. The birds were challenged with virulent IBDV at wk 3 postvaccination. Then the birds were weighed, bled, and necropsied at d 3 postchallenge and the bursae were sampled for gross and histopathological examination. Results demonstrated that GSLS provided a better protection against virulent IBDV challenge following vaccination than the control. In conclusion, oral administration of GSLS enhances both humoral and gut mucosal immune responses to IBDV and offers a better protection against virulent IBDV challenge. Considering its immunomodulatory properties to IBDV vaccine, GSLS might be a promising oral adjuvant for vaccination against infectious diseases in poultry.

Dietary rice bran protects against rotavirus diarrhea and promotes Th1-type immune responses to human rotavirus vaccine in gnotobiotic pigs.

Rice bran (RB) contains a distinct stoichiometry of phytochemicals that can promote gut mucosal immune responses against enteric pathogens. The effects of RB on rotavirus diarrhea and immunogenicity of an attenuated human rotavirus (HRV) vaccine were evaluated in gnotobiotic pigs. The four treatment groups studied were RB plus vaccine, vaccine only, RB only, and mock control. Pigs in the RB groups were fed the amount of RB that replaced 10% of the pigs' total daily calorie intake from milk starting from 5 days of age until they were euthanized. Pigs in the vaccine groups were orally inoculated with two doses of the attenuated HRV vaccine. A subset of pigs from each group was orally challenged with the homologous virulent HRV on postinoculation day 28. Diarrhea and virus shedding were monitored daily from postchallenge day 0 to day 7. RB feeding significantly protected against diarrhea upon virulent HRV challenge and enhanced the protective rate of the vaccine against rotavirus diarrhea. Consistent with protection, RB significantly increased gamma interferon (IFN-γ)-producing CD4(+) and CD8(+) T cell responses in intestinal and systemic lymphoid tissues. Furthermore, RB also increased the number of total IgM- and IgA-secreting cells, total serum IgM, IgG, and IgA titers, and HRV-specific IgA titers in intestinal contents. RB reduced the numbers of intestinal and systemic HRV-specific IgA and IgG antibody-secreting cells and reduced serum HRV-specific IgA and IgG antibody titers before the challenge. These results demonstrate clear beneficial effects of RB in protection against rotavirus diarrhea and stimulation of nonspecific and HRV-specific immune responses, as well as its biased Th1-type adjuvant effect for the vaccine.

Relationship between gut mucosal barrier dysfunction and immune response in patients with early severe acute pancreatitis

Objective To explore the relationship between gut mucosal barrier dysfunction and immune response in patients with early severe acute pancreatitis (SAP).Method 46 patients with early SAP were enrolled into this study from January 2010 to December 2012.Results The levels of endotoxin,the lactulose/mannitol (L/M) ratio,the D (-)-lactate concentration,and the proportion of HLA-DR-positive monocytes all decreased from a high level,while the frequency of Tregs increased during the first 14 days.The Th1/Th2 ratio decreased,with a decreased Th1 and an increased Th2 profile in the first week,but it subsequently increased,with an increased Th1 profile.Conclusions The data from this study showed that immunosuppression and immune imbalance happened in patients with early SAP,and showed a positive relationship with gut mucosal barrier dysfunction in patients with early SAP.Thus,early protection of the function of intestinal mucosal barrier is important in the treatment of SAP. Key words: Severe acute pancreas ; Gut mucosal barrier; Immune response

Impact of oral administration of compost extract on gene expression in the rat gastrointestinal tract

Oral administration of an extract consisting of compost fermented with thermophiles to pigs reduces the incidence of stillbirth and promotes piglet growth. However, the mechanism by which the compost extract modulates the physiological conditions of the animals remains largely unknown. Here, we investigate the effects of compost extract on the physiological responses in the intestine of a mammalian rat model. The level of fecal immunoglobulin A (IgA), which provides protection against pathogens and is secreted from the small intestine, was significantly higher in rats treated with continuous administration of the compost extract than in untreated rats after 2 months, but not after 1 month. However, the fecal IgA level was not significantly different in rats that received the filtered compost extract compared with the untreated rats or the rats that received the compost extract. Gene expression analyses of the small intestine indicated that several immune-related genes were upregulated following compost exposure. Specifically, the expression levels of lymphocyte chemoattractant chemokine CXCL13 and Granzyme B, which is released within cytotoxic T lymphocytes and natural killer cells, increased in the small intestinal tract following compost exposure. Based on these observations, it was postulated that the increased level of fecal IgA following compost exposure was associated with the expression of CXCL13 and Granzyme B in the intestinal tract. Thus, thermophile-fermented compost could contain microbes or substances that activate the rat's gut mucosal immune response.

Immunomodulatory effect of fibres, probiotics and synbiotics in different life-stages.

Chronic diseases associated to modern lifestyle habits are usually related to immune system malfunction. In this context, since diet is very well-known to modulate host resistance to infectious and inflammatory processes, the consumption of fibre and probiotics seems to be a promising nutritional tool for immune system modulation in different populations. Health effects of dietary fibres and probiotics have been extensively documented in numerous epidemiological and intervention studies, especially their beneficial effect on intestinal microbiota with important clinical implications in the prevention and/or treatment of infectious and inflammatory diseases. Mechanisms may include modulation of the functional properties of the microbiota, epithelial cells, dendritic cells and immune cell types. Prebiotics have been extensively reported to affect the composition of the gut microbiota, stimulating directly or indirectly putative beneficial gut commensals other than lactic acid bacteria, opening promising areas of research for the discovery of new probiotic strains and synbiotic combinations. Age-related changes in gut physiology, microbiota and mucosal immune response are well established. Moreover, exposure to different challenges during life such as early encounter of environmental insults in the newborn, infant formula feeding, antibiotic treatment, gastrointestinal diseases and stress, also interferes with the normal development and balance of the healthy gut microbiota. Therefore, the current short review gives an overview of today's main aspects of the effect of fibres, probiotics and synbiotics on the immune system in different life-stages.