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Remo Frei,
Ruth Ferstl,
Patrycja Konieczna,
Mario Ziegler,
Tunde Simon,
Tulia Mateus Rugeles,
Susanne Mailand,
Takeshi Watanabe,
Roger Lauener,
Cezmi A Akdis, Liam O'Mahony
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ABSTRACT: BACKGROUND: The induction of tolerance and protective immunity to microbes is significantly influenced by host- and microbiota-derived metabolites, such as histamine. OBJECTIVE: We sought to identify the molecular mechanisms for histamine-mediated modulation of pattern recognition receptor signaling. METHODS: Human monocyte-derived dendritic cells (MDDCs), myeloid dendritic cells, and plasmacytoid dendritic cells were examined. Cytokine secretion, gene expression, and transcription factor activation were measured after stimulation with microbial ligands and histamine. Histamine receptor 2 (H2R)-deficient mice, histamine receptors, and their signaling pathways were investigated. RESULTS: Histamine suppressed MDDC chemokine and proinflammatory cytokine secretion, nuclear factor κB and activator protein 1 activation, mitogen-activated protein kinase phosphorylation, and TH1 polarization of naive lymphocytes, whereas IL-10 secretion was enhanced in response to LPS and Pam3Cys. Histamine also suppressed LPS-induced myeloid dendritic cell TNF-α secretion and suppressed CpG-induced plasmacytoid dendritic cell IFN-α gene expression. H2R signaling through cyclic AMP and exchange protein directly activated by cyclic AMP was required for the histamine effect on LPS-induced MDDC responses. Lactobacillus rhamnosus, which secretes histamine, significantly suppressed Peyer patch IL-2, IL-4, IL-5, IL-12, TNF-α, and GM-CSF secretion in wild-type but not H2R-deficient animals. CONCLUSION: Both host- and microbiota-derived histamine significantly alter the innate immune response to microbes through H2R.
The Journal of allergy and clinical immunology 03/2013; · 9.17 Impact Factor
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ABSTRACT: There is increasing interest in the administration of microbes or microbial metabolites for the prevention and treatment of aberrant inflammatory activity. The protective effects associated with these microbes are mediated by multiple mechanisms involving epithelial cells, DCs and T cells, but most data are derived from animal models. In this addendum, we summarize our recent data, showing that oral consumption of Bifidobacterium infantis 35624 is associated with enhanced IL-10 secretion and Foxp3 expression in human peripheral blood. In addition, we discuss the potential DC subset-specific mechanisms, which could contribute to DC(REG) and T(REG) programming by specific gut microbes.
Gut Microbes 05/2012; 3(3):261-6.
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ABSTRACT: Salmonella-induced damage to the small intestine may decrease the villi-associated enzyme activity, causing malabsorption of nutrients and diarrhea, and thus contribute to the symptoms of infection. The objective of this study was to determine the mechanism by which different doses and durations of Salmonella infection and lipopolysaccharide (LPS) affect brush border enzyme activity in the mouse, and to determine if the probiotic Bifidobacterium longum subspecies infantis 35624 could attenuate the intestinal damage.
BALB/c mice were challenged with Salmonella enterica serovar Typhimurium UK1 at various doses (10(2)-10(8) colony-forming unit (CFU)) and durations (10(6) CFU for 1-6 days). Mice were also treated with B. longum subsp. infantis 35624 for 2 weeks before and during a 6-day S. Typhimurium challenge (10(6) CFU), or before injection of LPS. The small intestine was assessed for morphological changes, mRNA expression of cytokines, and activity of the brush border enzymes sucrase-isomaltase, maltase, and alkaline phosphatase.
S. Typhimurium infection significantly reduced the activity of all brush border enzymes in a dose- and time-dependent manner (P<0.05). This also occurred following injection of LPS. Pre-treatment with B. longum subsp. infantis 35624 prevented weight loss, protected brush border enzyme activity, reduced the small intestinal damage, and inhibited the increase in interleukin (IL)-10 and IL-8 expression due to Salmonella challenge.
Salmonella infection reduces the small intestinal brush border enzyme activity in mice, with the level of reduction and associated weight loss increasing with dose and duration of infection. B. longum subsp. infantis 35624 treatment attenuated the effect of Salmonella infection on brush border enzyme activity and weight loss, which may be due to modulation of the host immune response.
Clinical and translational gastroenterology. 01/2012; 3:e15.
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ABSTRACT: Histamine influences many cell types involved in the regulation of innate and adaptive immune responses including antigen-presenting cells (APCs), Natural Killer (NK) cells, epithelial cells, T lymphocytes and B lymphocytes. These cells express histamine receptors (HRs) and also secrete histamine, which can selectively recruit the major effector cells into tissue sites and affect their maturation, activation, polarization and effector functions leading to tolerogenic or pro-inflammatory responses. Histamine and its four receptors represent a complex system of immunoregulation with distinct effects of receptor subtypes and their differential expression, which changes according to the stage of cell differentiation as well as micro-environmental influences. In this review, we discuss histamine receptor expression and differential activation of cells within both the innate and adaptive immune response and the signal transduction mechanisms which influence their activity.
Frontiers in Bioscience 01/2012; 17:40-53. · 3.52 Impact Factor
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ABSTRACT: Intestinal homoeostasis is dependent on immunological tolerance to the microbiota.
To (1) determine if a probiotic could induce Foxp3 T cells in humans; (2) to elucidate the molecular mechanisms, which are involved in the induction of Foxp3 T cells by human dendritic cells.
Cytokine secretion and Foxp3 expression were assessed in human volunteers following Bifidobacterium infantis feeding. Monocyte-derived dendritic cells (MDDCs), myeloid dendritic cells (mDCs) and plasmacytoid dendritic cells (pDCs) were incubated in vitro with B. infantis and autologous lymphocytes. Transcription factor expression, costimulatory molecule expression, cytokine secretion, retinoic acid and tryptophan metabolism were analysed.
Volunteers fed B. infantis displayed a selective increase in secretion of interleukin (IL)-10 and enhanced Foxp3 expression in peripheral blood. In vitro, MDDCs, mDCs and pDCs expressed indoleamine 2,3-dioxygenase and secreted IL-10, but not IL-12p70, in response to B. infantis. MDDC and mDC IL-10 secretion was Toll-like receptor (TLR)-2/6 dependent, while pDC IL-10 secretion was TLR-9 dependent. In addition, MDDCs and mDCs expressed RALDH2, which was TLR-2 and DC-SIGN dependent. B. infantis-stimulated MDDCs, mDCs and pDCs induced T cell Foxp3 expression. TLR-2, DC-SIGN and retinoic acid were required for MDDC and mDC induction of Foxp3 T cells, while pDCs required indoleamine 2,3-dioxygenase.
B. infantis administration to humans selectively promotes immunoregulatory responses, suggesting that this microbe may have therapeutic utility in patients with inflammatory disease. Cross-talk between multiple pattern-recognition receptors and metabolic pathways determines the innate and subsequent T regulatory cell response to B. infantis. These findings link nutrition, microbiota and the induction of tolerance within the gastrointestinal mucosa.
Gut 11/2011; 61(3):354-66. · 10.11 Impact Factor
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ABSTRACT: Histamine is a biogenic amine with extensive effects on many cell types, including important immunologic cells, such as antigen-presenting cells, natural killer cells, epithelial cells, and T and B lymphocytes. Histamine and its 4 receptors represent a complex system of immunoregulation with distinct effects dependent on receptor subtypes and their differential expression. These are influenced by the stage of cell differentiation, as well as microenvironmental influences, leading to the selective recruitment of effector cells into tissue sites accompanied by effects on cellular maturation, activation, polarization, and effector functions, which lead to tolerogenic or proinflammatory responses. In this review we discuss the regulation of histamine secretion, receptor expression, and differential activation of cells within both the innate and adaptive immune responses. It is clear that the effects of histamine on immune homeostasis are dependent on the expression and activity of the 4 currently known histamine receptors, and we also recognize that 100 years after the original identification of this biogenic amine, we still do not fully understand the complex regulatory interactions between histamine and the host immune response to everyday microbial and environmental challenges.
The Journal of allergy and clinical immunology 08/2011; 128(6):1153-62. · 9.17 Impact Factor
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The Journal of allergy and clinical immunology 06/2011; 127(6):1541-2. · 9.17 Impact Factor
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Hiroyuki Fujita,
Maciej Chalubinski,
Claudio Rhyner,
Philippe Indermitte,
Norbert Meyer,
Ruth Ferstl,
Angela Treis,
Enrique Gomez,
Ahmet Akkaya, Liam O'Mahony,
Mübeccel Akdis,
Cezmi A Akdis
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ABSTRACT: Increased airway smooth muscle (ASM) mass is an essential component of airway remodeling and asthma development, and there is no medication specifically against it. Tight junction (TJ) proteins, which are expressed in endothelial and epithelial cells and affect tissue integrity, might exist in other types of cells and display additional functions in the asthmatic lung.
The aim of this study was to investigate the existence, regulation, and function of TJ proteins in ASM in asthmatic patients.
The expression and function of TJ proteins in primary ASM cell lines, human bronchial biopsy specimens, and a murine model of asthma were analyzed by means of RT-PCR, multispectral imaging flow cytometry, immunohistochemistry, Western blotting, 5-(and-6)-carboxyfluorescein diacetate succinimidyl ester staining, tritiated thymidine incorporation, wound-healing assay, and luminometric bead array.
Increased claudin-1 expression was observed in ASM of asthmatic patients, as well as in a murine model of asthma-like airway inflammation. Whereas IL-1β and TNF-α upregulated claudin-1 expression, it was downregulated by the T(H)2 cytokines IL-4 and IL-13 in primary human ASM cells. Claudin-1 was localized to the nucleus and cytoplasm but not to the cell surface in ASM cells. Claudin-1 played a central role in ASM cell proliferation, as demonstrated by increased ASM cell proliferation seen with overexpression and decreased proliferation seen with small interfering RNA knockdown of claudin-1. Overexpression of claudin-1 induced vascular endothelial growth factor and downregulated IL-6, IL-8, and IFN-γ-induced protein 10 production by ASM cells. Claudin-1 upregulation by IL-1β or TNF-α was suppressed by dexamethasone but not by rapamycin, FK506, or salbutamol.
These results demonstrate that claudin-1 might play a role in airway remodeling in asthmatic patients by means of regulation of ASM cell proliferation, angiogenesis, and inflammation.
The Journal of allergy and clinical immunology 06/2011; 127(6):1612-21.e8. · 9.17 Impact Factor
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Mübeccel Akdis,
Simone Burgler,
Reto Crameri,
Thomas Eiwegger,
Hiroyuki Fujita,
Enrique Gomez,
Sven Klunker,
Norbert Meyer, Liam O'Mahony,
Oscar Palomares,
Claudio Rhyner,
Nadia Ouaked,
Nadia Quaked,
Anna Schaffartzik,
Willem Van De Veen,
Sabine Zeller,
Maya Zimmermann,
Cezmi A Akdis
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ABSTRACT: Advancing our understanding of mechanisms of immune regulation in allergy, asthma, autoimmune diseases, tumor development, organ transplantation, and chronic infections could lead to effective and targeted therapies. Subsets of immune and inflammatory cells interact via ILs and IFNs; reciprocal regulation and counter balance among T(h) and regulatory T cells, as well as subsets of B cells, offer opportunities for immune interventions. Here, we review current knowledge about ILs 1 to 37 and IFN-γ. Our understanding of the effects of ILs has greatly increased since the discoveries of monocyte IL (called IL-1) and lymphocyte IL (called IL-2); more than 40 cytokines are now designated as ILs. Studies of transgenic or knockout mice with altered expression of these cytokines or their receptors and analyses of mutations and polymorphisms in human genes that encode these products have provided important information about IL and IFN functions. We discuss their signaling pathways, cellular sources, targets, roles in immune regulation and cellular networks, roles in allergy and asthma, and roles in defense against infections.
The Journal of allergy and clinical immunology 03/2011; 127(3):701-21.e1-70. · 9.17 Impact Factor
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ABSTRACT: We have previously demonstrated that oral administration of a metabolically active Bifidobacterium breve strain, with ability to form cis-9, trans-11 conjugated linoleic acid (CLA), resulted in modulation of the fatty acid composition of the host, including significantly elevated concentrations of c9, t11 CLA and omega-3 (n-3) fatty acids in liver and adipose tissue. In this study, we investigated whether a recombinant lactobacillus expressing linoleic acid isomerase (responsible for production of t10, c12 CLA) from Propionibacterium acnes (PAI) could influence the fatty acid composition of different tissues in a mouse model. Linoleic-acid-supplemented diets (2 %, w/w) were fed in combination with either a recombinant t10, c12 CLA-producing Lactobacillus paracasei NFBC 338 (Lb338), or an isogenic (vector-containing) control strain, to BALB/c mice for 8 weeks. A third group of mice received linoleic acid alone (2 %, w/w). Tissue fatty acid composition was assessed by GLC at the end of the trial. Ingestion of the strain expressing linoleic acid isomerase was associated with a 4-fold increase (P<0.001) in t10, c12 CLA in adipose tissues of the mice when compared with mice that received the isogenic non-CLA-producing strain. The livers of the mice that received the recombinant CLA-producing Lb338 also contained a 2.5-fold (albeit not significantly) higher concentration of t10, c12 CLA, compared to the control group. These data demonstrate that a single gene (encoding linoleic acid isomerase) expressed in an intestinal microbe can influence the fatty acid composition of host fat.
Microbiology 02/2011; 157(Pt 2):609-15. · 3.06 Impact Factor
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Carola T Murphy,
Gerard Moloney,
John Macsharry,
Andrea Haynes,
Emilie Faivre,
Aoife Quinlan,
Peter G McLean,
Kevin Lee, Liam O'Mahony,
Fergus Shanahan,
Silvia Melgar,
Kenneth Nally
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ABSTRACT: Leukocyte trafficking is a therapeutic target in IBD. The integrins α₄β and α₄β₁ regulate leukocyte migration into tissues and lymphoid organs. Current strategies rely on biologics, such as mAb, to inhibit leukocyte recruitment. Here we show the in vivo therapeutic effects of a small molecule α4-integrin antagonist (GSK223618A) in a leukocyte-trafficking model and a murine model of colitis. Leukocytes isolated from MLNs of transgenic β-actin-luc+ mice were injected i.v. into recipients with DSS-induced colitis. Recipient mice were orally gavaged with vehicle or an α₄-integrin antagonist 1 h pre-adoptive transfer, followed by bioluminescence whole body and ex vivo organ imaging 4 h post-transfer. To confirm its therapeutic effect, the α₄-integrin antagonist was given orally twice daily for 6 days to mice with DSS-induced colitis, starting on Day 3. Clinical, macroscopic, and histological signs of inflammation were assessed and gene-expression profiles analyzed. Using bioluminescence imaging, we tracked and quantified leukocyte migration to the inflamed gut and demonstrated its inhibition by a small molecule α₄-integrin antagonist. Additionally, the therapeutic effect of the antagonist was confirmed in DSS-induced colitis in terms of clinical, macroscopic, and histological signs of inflammation. Gene expression analysis suggested enhancement of tissue healing in compound-treated animals. Inhibition of leukocyte trafficking using small molecule integrin antagonists is a promising alternative to large molecule biologics. Furthermore, in vivo bioluminescence imaging is a valuable strategy for preclinical evaluation of potential therapeutics that target leukocyte trafficking in inflammatory diseases.
Journal of leukocyte biology 12/2010; 88(6):1271-8. · 4.99 Impact Factor
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ABSTRACT: Experimental and clinical studies suggest an association between small intestinal bacterial overgrowth (SIBO) and nonalcoholic steatohepatitis (NASH). Liver injury and fibrosis could be related to exposure to bacterial products of intestinal origin and, most notably, endotoxin, including lipopolysaccharide (LPS).
To compare the prevalence of SIBO and its relationships to LPS receptor levels and systemic cytokines in NASH patients and healthy control subjects.
Eighteen NASH patients (eight males) and 16 age-matched and gender-matched healthy volunteers were studied. SIBO was assessed by the lactulose breath hydrogen test (LHBT), plasma lipopolysaccharide binding protein (LBP) levels by ELISA, and expression (as a percentage) of TLR-2 and 4 on CD14-positive cells by flow cytometry. Pro-inflammatory cytokines (IL-1β, IL-6, IL-8, and TNF-α) were measured in plasma.
SIBO was more common in NASH patients than control subjects (77.78% vs. 31.25%; P < 0.0001). LBP levels and TLR-2 expression were similar in both groups, TLR-4/MD-2 expression on CD14 positive cells was higher among NASH patients: expression, mean ± SEM, NASH vs. control: 20.95 ± 2.91% vs. 12.73 ± 2.29%, P < 0.05. Among the examined cytokines, only IL-8 levels were significantly higher in patients than control (P = 0.04) and correlated positively with TLR-4 expression (r = 0.5123, P = 0.036).
NASH patients have a higher prevalence of small intestinal bacterial overgrowth which is associated with enhanced expression of TLR-4 and release of IL-8. SIBO may have an important role in NASH through interactions with TLR-4 and induction of the pro-inflammatory cytokine, IL-8.
Digestive Diseases and Sciences 11/2010; 56(5):1524-34. · 2.12 Impact Factor
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ABSTRACT: Recently, we reported that administration of Bifidobacteria resulted in increased concentrations of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in murine adipose tissue [1]. The objective of this study was to assess the impact of co-administration of Bifidobacterium breve NCIMB 702258 and the substrate for EPA, alpha-linolenic acid, on host fatty acid composition. alpha-Linolenic acid-supplemented diets (1%, wt/wt) were fed to mice (n = 8), with or without B. breve NCIMB 702258 (daily dose of 10(9) microorganisms) for 8 weeks. Two further groups received either supplement of B. breve alone or unsupplemented diet. Tissue fatty acid composition was assessed by gas liquid chromatography. Dietary supplementation of alpha-linolenic acid resulted in higher (P < 0.05) alpha-linolenic acid and EPA concentrations in liver and adipose tissue and lower (P < 0.05) arachidonic acid in liver, adipose tissue and brain compared with mice that did not receive alpha-linolenic acid. Supplementation with B. breve NCIMB 702258 in combination with alpha-linolenic acid resulted in elevated (P < 0.05) liver EPA concentrations compared with alpha-linolenic acid supplementation alone. Furthermore, the former group had higher (P < 0.05) DHA in brain compared with the latter group. These results suggest a role for interactions between fatty acids and commensals in the gastrointestinal tract. This interaction between administered microbes and fatty acids could result in a highly effective nutritional approach to the therapy of a variety of inflammatory and neurodegenerative conditions.
Lipids 05/2010; 45(5):429-36. · 2.13 Impact Factor
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ABSTRACT: Do gastrointestinal symptoms in patients with inflammatory bowel disease (IBD) in apparent remission reflect the coexistence of irritable bowel syndrome (IBS) or subclinical inflammation? The aims of this study were as follows: (i) to prospectively determine the prevalence of IBS symptoms in IBD patients in remission; and (ii) to determine whether IBS symptoms correlate with levels of fecal calprotectin.
Remission was defined by physician assessment: Crohn's disease (CD) activity index <or=150 and ulcerative colitis disease activity index <or=3, and serum C-reactive protein <10, while off corticosteroids or biologics. Quality of life (QOL) (by inflammatory bowel disease questionnaire), the hospital anxiety and depression scale (HAD), and fecal calprotectin were measured.
Rome II criteria for IBS were fulfilled in 37/62 (59.7%) of CD patients and by 17/44 (38.6%) of those with ulcerative colitis (UC). However, fecal calprotectin was significantly elevated above the upper limit of normal in both IBD patient groups, indicating the presence of occult inflammation. Furthermore, calprotectin levels were significantly higher in CD and UC patients with criteria for IBS than in those without IBS-type symptoms. QOL scores were lower and HAD scores higher among UC patients with IBS symptoms in comparison to those who did not have IBS symptoms.
IBS-like symptoms are common in patients with IBD who are thought to be in clinical remission, but abnormal calprotectin levels suggest that the mechanism in most cases is likely to be occult inflammation rather than coexistent IBS.
The American Journal of Gastroenterology 04/2010; 105(8):1788, 1789-94; quiz 1795. · 7.28 Impact Factor
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ABSTRACT: The immune response is a tightly regulated process, which normally results in protection from infection and tolerance of innocuous environmental antigens. However, in allergic disease, the activated immune response results in a chronic pro-inflammatory state characterized by antibody secretion (IgE) and T cell activation to normally well-tolerated antigens. Currently, the treatment of allergic disease is focused on the suppression of key inflammatory mediators or inflammatory cell populations and include anti-histamines, anti-leukotrienes, β2 adrenergic receptor agonists and corticosteroids. However, these approaches only provide a temporary suppression of disease symptoms. Successful long-term treatment can only be provided by allergen-specific immunotherapy (allergen-SIT), which restores normal immunity against allergens. This review will discuss novel approaches to the management of allergy and asthma by targeting the T regulatory cell via modulation of the commensal microbiota and allergen-SIT.
Autoimmunity 04/2010; 43(7):493-503. · 2.47 Impact Factor
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ABSTRACT: Although probiotics are generally considered to be safe, their increasingly widespread use warrants better understanding of their risks in companion animals. This study evaluated the safety and tolerance of dietary supplementation with a canine-derived probiotic, Bifidobacterium animalis strain AHC7 (Prostora, Procter & Gamble Pet Care), fed to growing beagles beginning at approximately 6 months of age (11 males; 9 females). Probiotic B. animalis AHC7 administered orally once per day at a dose of up to 5 x 1010 colony-forming units for at least 12 consecutive weeks was well tolerated with no safety concerns.
Veterinary therapeutics: research in applied veterinary medicine 01/2010; 11(3):E1-E14. · 1.69 Impact Factor
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David O'Mahony,
Sharon Murphy,
Thomas Boileau,
Jeansoon Park,
Frances O'Brien,
David Groeger,
Patrycja Konieczna,
Mario Ziegler,
Paul Scully,
Fergus Shanahan,
Barry Kiely, Liam O'Mahony
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ABSTRACT: Bifidobacteria and lactobacilli are among the early and important colonizers of the gastrointestinal tract and are generally considered to be part of a normal, healthy microbiota. It is believed that specific strains within the microbiota can influence host immune-reactivity and may play a role in protection from infection and aberrant inflammatory activity. One such strain, Bifidobacterium animalis AHC7, has been previously shown to protect against Salmonella typhimurium infection in mice and helps resolve acute idiopathic diarrhea in dogs. The aim of this study was to investigate the potential molecular and cellular mechanisms underpinning the Bifidobacterium animalis AHC7 protective effect.
Following 4 hours of infection with Salmonella typhimurium, NF-κB activation was significantly elevated in vivo in placebo and Enterococcus faecium-fed animals while Bifidobacterium animalis AHC7 consumption significantly attenuated the NF-κB response. In vitro anti-CD3/CD28 stimulated Peyer's patch cells secreted significantly less TNF-α and IFN-γ following Bifidobacterium animalis AHC7 consumption. Stimulated cells released more IL-12p70 but this difference did not reach statistical significance. No alteration in mucosal IL-6, IL-10 or MCP-1 levels were observed. No statistically significant change in the cytokine profile of mesenteric lymph node cells was noted. In vitro, Bifidobacterium animalis AHC7 was bound by dendritic cells and induced secretion of both IL-10 and IL-12p70. In addition, co-culture of CD4+ T cells with Bifidobacterium animalis AHC7-stimulated dendritic cells resulted in a significant increase in CD25+Foxp3+ T cell numbers.
Bifidobacterium animalis AHC7 exerts an anti-inflammatory effect via the attenuation of pro-inflammatory transcription factor activation in response to an infectious insult associated with modulation of pro-inflammatory cytokine production within the mucosa. The cellular mechanism underpinning Bifidobacterium animalis AHC7 mediated attenuation of NF-κB activation may include recognition of the bacterium by dendritic cells and induction of CD25+Foxp3+ T cells.
BMC Immunology 01/2010; 11:63. · 2.53 Impact Factor
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ABSTRACT: Crohn's disease (CD) is a multifactorial syndrome with genetic and environmental contributions. Mycobacterium avium subspecies paratuberculosis (MAP) has been frequently isolated from mucosal tissues of patients with CD but the cellular immune response to this bacterium has been poorly described. Our aim was to examine the influence of MAP on T-cell proliferation and cytokine responses in patients with inflammatory bowel disease (IBD).
Peripheral blood mononuclear cells (PBMCs) and mesenteric lymph node cells (MLNCs) were obtained from IBD patients and non-IBD controls. PBMC T-cell proliferation in response to MAP was determined using CFSE labeling and flow cytometry. The specificity of cytokine responses to MAP was controlled by parallel exposure to Listeria monocytogenes (LM) or Salmonella typhimurium (ST).
Coincubation of PBMCs with MAP induced significantly more T-cell proliferation (P < 0.0001) in PBMCs isolated from CD patients compared to PBMCs obtained from ulcerative colitis (UC) patients or healthy volunteers. In addition, PBMCs from CD patients secreted significantly higher (P < 0.05) levels of tumor necrosis factor-alpha (TNF-alpha; 2302 +/- 230 pg/mL) and interleukin (IL)-10 (299 +/- 48 pg/mL) in response to MAP compared to UC patients (TNF-alpha: 1219 +/- 411 pg/mL; IL-10: 125 +/- 19 pg/mL) and controls (TNF-alpha: 1447 +/- 173 pg/mL; IL-10: 127 +/- 12 pg/mL). No difference in cytokine responses was observed in response to LM or ST. MLNCs from both CD and UC patients secreted significantly more TNF-alpha and IL-8 in response to MAP compared to MLNCs from non-IBD control patients.
Increased proliferation of T cells and an altered cytokine response suggest that prior exposure to MAP and engagement of the immune system is common in patients with CD. This does not imply causation but does support further examination of this bacterium as an environmental modifying factor.
Inflammatory Bowel Diseases 10/2009; 16(2):296-304. · 4.86 Impact Factor
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ABSTRACT: Human intestinal epithelial cells (IECs) secrete the chemokine CCL20 in response to infection by various enteropathogenic bacteria or exposure to bacterial flagellin. CCL20 recruits immature dendritic cells and lymphocytes to target sites. Here we investigated IEC responses to various pathogenic and commensal bacteria as well as the modulatory effects of commensal bacteria on pathogen-induced CCL20 secretion. HT-29 human IECs were incubated with commensal bacteria (Bifidobacterium infantis or Lactobacillus salivarius), or with Salmonella typhimurium, its flagellin, Clostridium difficile, Mycobacterium paratuberculosis, or Mycobacterium smegmatis for varying times. In some studies, HT-29 cells were pre-treated with a commensal strain for 2 hr prior to infection or flagellin stimulation. CCL20 and interleukin (IL)-8 secretion and nuclear factor (NF)-kappaB activation were measured using enzyme-linked immunosorbent assays.
Compared to untreated cells, S. typhimurium, C. difficile, M. paratuberculosis, and flagellin activated NF-kappaB and stimulated significant secretion of CCL20 and IL-8 by HT-29 cells. Conversely, B. infantis, L. salivarius or M. smegmatis did not activate NF-kappaB or augment CCL20 or IL-8 production. Treatment with B. infantis, but not L. salivarius, dose-dependently inhibited the baseline secretion of CCL20. In cells pre-treated with B. infantis, C. difficile-, S. typhimurium-, and flagellin-induced CCL20 were significantly attenuated. B. infantis did not limit M. Paratuberculosis-induced CCL20 secretion.
This study is the first to demonstrate that a commensal strain can attenuate CCL20 secretion in HT-29 IECs. Collectively, the data indicate that M. paratuberculosis may mediate mucosal damage and that B. infantis can exert immunomodulatory effects on IECs that mediate host responses to flagellin and flagellated enteric pathogens.
BMC Immunology 10/2009; 10:54. · 2.53 Impact Factor
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ABSTRACT: The vagus nerve is a conduit for bidirectional signaling between the brain and the viscera. Vagal signaling has been shown to downregulate gastrointestinal inflammation, and the mechanism is thought to involve acetylcholine binding to the alpha-7 subunit of the nicotinic acetylcholine receptor on macrophages. The aims of this study were to quantify the impact of vagotomy in vivo by visualizing nuclear factor (NF)-kappaB activity and to determine if the proinflammatory impact of vagotomy could be transferred by lymphocytes. Real-time biophotonic imaging revealed that subdiaphragmatic vagotomy resulted in increased levels of NF-kappaB in vivo. NF-kappaB activation was further exaggerated in vivo following exposure to 4% DSS for 5 days. Vagotomized animals also exhibited higher disease activity scores and secreted more proinflammatory cytokines. Adoptive transfer of CD4(+) T cells from vagotomized animals (but not CD4(+) T cells from sham-operated controls) to naive dextran sulfate sodium (DSS)-treated recipients resulted in increased inflammatory scores. Further examination of the CD4(+) T cells revealed that adoptive transfer of the CD25(-) population alone from vagotomized donors (but not sham-operated donors) was sufficient to aggravate colitis in DSS-treated recipients. Increased DSS-induced inflammation was associated with reduced CD4(+)CD25(+)Foxp3(+) regulatory T cell numbers in recipients. This study clearly demonstrates the ability of the vagus nerve to modulate activity of the proinflammatory transcription factor NF-kappaB in vivo. The proinflammatory effect of vagotomy is transferable using splenic T cells and highlights a previously unappreciated cellular mechanism for linking central parasympathetic processes with mucosal inflammation and immune homeostasis.
AJP Regulatory Integrative and Comparative Physiology 09/2009; 297(4):R1118-26. · 3.34 Impact Factor
