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Mühlbauer M, Cheely AW, Yenugu S, Jobin C. Regulation and functional impact of lipopolysaccharide induced Nod2 gene expression in the murine epididymal epithelial cell line PC1. Immunology 2008; 124:256-64. [PMID: 18284470 DOI: 10.1111/j.1365-2567.2007.02763.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Epididymitis represents a serious threat to male fertility and usually develops following secondary bacterial infection of the epididymis such as urinary tract infections or sexually transmitted diseases. Surprisingly, very little is known about the innate host response triggered by bacterial infection in the male reproductive tract. In this study we investigated the regulation and function of Nod2 in epididymal epithelial cells following lipopolysaccharide (LPS) stimulation. The immortalized epididymal epithelial cell line PC1 (proximal caput 1) constitutively expressed Toll-like receptor 4, MD-2, CD-14 but not Nod2 messenger RNA. Lipopolysaccharide (LPS; 0.5 microg/ml) rapidly induced I kappaB phosphorylation and degradation, RelA nuclear translocation and phosphorylation, which correlated with enhanced transcriptional activity (four-fold) in PC1 cells. The LPS and lipid A rapidly (1 hr) induced Nod2 messenger RNA accumulation in a dose-dependent manner. RelA and RNApolII recruitment to the Nod2 gene promoter was enhanced in LPS-stimulated cells. Molecular blockade of nuclear factor-kappaB signalling with adenovirus 5 (Ad5) I kappaB AA or adenovirus 5 double-negative (Ad5dn) IKK beta prevented LPS-induced Nod2 gene expression. Functionally, Nod2 upregulation enhanced muramyl dipeptide (MDP) -induced tumour necrosis factor messenger RNA accumulation in PC1 cells. We conclude that epididymal epithelial cells mount an innate response following LPS exposure which leads to upregulation of Nod2 and enhanced responsiveness to the microbial product MDP. The rapid Nod2 upregulation in epididymal epithelial cells is probably part of a complex innate host response aimed at protecting the male reproductive tract from the deleterious impact of bacteria.
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Affiliation(s)
- Marcus Mühlbauer
- Department of Medicine and Center for GI Biology and Diseases, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
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202
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Abtin A, Eckhart L, Mildner M, Gruber F, Schröder JM, Tschachler E. Flagellin is the principal inducer of the antimicrobial peptide S100A7c (psoriasin) in human epidermal keratinocytes exposed to Escherichia coli. FASEB J 2008; 22:2168-76. [PMID: 18263703 DOI: 10.1096/fj.07-104117] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Epidermal keratinocytes (KCs) express antimicrobial peptides as a part of the innate immune response. It has recently been shown that the culture supernatant of Escherichia coli induces the expression of S100A7c (psoriasin) in KCs and that S100A7c efficiently kills E. coli. Here we have investigated which of the microbial components triggers the up-regulation of S100A7c expression. Exposure of human primary KCs to ligands of the human Toll-like receptors (TLRs) revealed that only the TLR5 ligand flagellin strongly induced the expression of S100A7c mRNA and protein, whereas all other TLR ligands had no significant effect. In contrast to the supernatant from flagellated wild-type (WT) E. coli, the supernatant of a flagellin-deficient E. coli strain (DeltaFliC) did not induce S100A7c expression. Small interfering RNA-mediated knockdown of TLR5 expression suppressed the ability of KCs to up-regulate S100A7c expression in response to both flagellin and WT E. coli supernatant. Taken together, our data demonstrate that bacterial flagellin is essential and sufficient for the induction of S100A7c expression in KCs by E. coli.
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Affiliation(s)
- Arby Abtin
- Department of Dermatology, Medical University of Vienna, Waehringer Guertal 18-20, 1090 Vienna, Austria
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203
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Adams RJ, Heazlewood SP, Gilshenan KS, O'Brien M, McGuckin MA, Florin THJ. IgG antibodies against common gut bacteria are more diagnostic for Crohn's disease than IgG against mannan or flagellin. Am J Gastroenterol 2008; 103:386-96. [PMID: 17924999 DOI: 10.1111/j.1572-0241.2007.01577.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
INTRODUCTION Antibodies to baker's yeast (mannan) have been widely used to aid in diagnosis of Crohn's disease. Recently, there has been interest in antibodies against a flagellin from Clostridium coccoides subphylum. We hypothesized that reactivity with these antigens is a surrogate marker for a generalized increased IgG response against intestinal microbiota in Crohn's disease. METHODS We compared the diagnostic utility of IgG antibodies against flagellin and mannan with two complex surface antigen preparations, one derived from B. vulgatus (Bv), the other from over 20 common mucosa-associated microbiota, a multibacterial membrane preparation (MBP). IgG antibodies were measured in sera from two age- and sex-matched populations: 120 Crohn's patients (CD) and 160 gastroenterology controls (CON) comprising 40 ulcerative colitis (UC) and 120 non-IBD patients. RESULTS IgG was elevated against all antigen preparations in Crohn's but statistical analysis of receiver operator characteristic (ROC) plots showed that IgG against the complex antigen preparations MBP and Bv had better diagnostic accuracy to distinguish the two populations (CD and CON) than IgG against mannan (P < or = 0.01) or flagellin (P < or = 0.04). Concentrations of antibody reactive with distinct individual antigens correlated weakly. DISCUSSION The findings support our hypothesis that measurement of IgG reactivity against individual antigens gives an indication of a generalized increased IgG response against individual intestinal microbiota in Crohn's, rather than measuring specific immune responses important for pathogenesis. The data are consistent with either a mucosal defect that facilitates increased exposure to microbial antigens or an altered immune response, both of which could occur due to known genetic and molecular defects in Crohn's disease.
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Affiliation(s)
- Rachel J Adams
- IBD Team, Mucosal Diseases Program, Mater Medical Research Institute, South Brisbane, Australia
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204
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Sirard JC, Vignal C, Dessein R, Chamaillard M. Nod-like receptors: cytosolic watchdogs for immunity against pathogens. PLoS Pathog 2008; 3:e152. [PMID: 18166077 PMCID: PMC2156082 DOI: 10.1371/journal.ppat.0030152] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
In mammals, tissue-specific sets of pattern-recognition molecules, including Nod-like receptors (NLR), enable concomitant and sequential detection of microbial-associated molecular patterns from both the extracellular and intracellular microenvironment. Repressing and de-repressing the cytosolic surveillance machinery contributes to vital immune homeostasis and protective responses within specific tissues. Conversely, defective biology of NLR drives the development of recurrent infectious, autoimmune and/or inflammatory diseases by failing to mount barrier functions against pathogens, to tolerate commensals, and/or to instruct the adaptive immune response against microbes. Better decoding microbial strategies that are evolved to circumvent NLR sensing will provide clues for the development of rational therapies aimed at curing and/or preventing common and emerging immunopathologies.
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205
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Nalubamba KS, Gossner AG, Dalziel RG, Hopkins J. Differential expression of pattern recognition receptors during the development of foetal sheep. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2008; 32:869-874. [PMID: 18262265 DOI: 10.1016/j.dci.2007.12.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2007] [Revised: 12/12/2007] [Accepted: 12/25/2007] [Indexed: 05/25/2023]
Abstract
Pattern recognition receptors (PRRs) play a crucial role in the initiation of the adaptive immune response. Immunological competence of foetal lambs occurs progressively throughout gestation, and in order to understand the role played by PRRs in foetal immunological competence, we quantified transcript expression, in the skin and spleen, of the TLRs, key C-type lectins and CARD15 during the critical second trimester. These data show that lambs express the same spectrum of PRRs as the adult but that the level of expression for most is dependent on developmental age. Key findings include: TLR1 and TLR5 are expressed at high levels in the foetus but are low in the adult; in contrast, TLR4, CD14 and CARD15 increase with age. In addition, TLR9 and TLR10 are expressed by the spleen and not the skin, while CARD15 is low in the spleen and high in the skin.
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Affiliation(s)
- King S Nalubamba
- Centre of Infectious Diseases, Royal (Dick) School of Veterinary Studies, University of Edinburgh, Summerhall, Edinburgh EH9 1QH, UK
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206
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Recipient NOD2/CARD15 Variants: A Novel Independent Risk Factor for the Development of Bronchiolitis Obliterans after Allogeneic Stem Cell Transplantation. Biol Blood Marrow Transplant 2008; 14:67-74. [DOI: 10.1016/j.bbmt.2007.09.009] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2007] [Accepted: 09/20/2007] [Indexed: 01/07/2023]
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207
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Röhrl J, Yang D, Oppenheim JJ, Hehlgans T. Identification and Biological Characterization of Mouse beta-defensin 14, the orthologue of human beta-defensin 3. J Biol Chem 2007; 283:5414-9. [PMID: 18167348 DOI: 10.1074/jbc.m709103200] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
beta-Defensins are small antimicrobial polypeptides that are mainly expressed by epithelial cells and play an important role in the antimicrobial innate immune response. In addition to the direct microbicidal effects of these polypeptides, it became evident that certain members of the beta-defensin super family have the capacity to promote local innate inflammatory and systemic adaptive immune responses by interacting with the CC-chemokine receptor CCR6. We have identified mouse beta-defensin 14 (mBD14, Defb14) as an orthologue of human beta-defensin 3 (hBD3 or DEFB103). Based on primary structural analysis, mBD14 demonstrates greater (68%) homology to its human orthologue, containing three conserved cystein linkages, characteristic for the beta-defensin super family. mBD14 is expressed in a wide variety of tissues including spleen, colon, and tissues of the upper and lower respiratory tract. Interestingly, we also detected mBD14 expression in immature CD11c+ bone marrow-derived dendritic cells. The expression of mBD14 can be induced by Toll-like receptor agonists such as lipopolysaccharide and poly(I:C) and by pro-inflammatory stimuli e.g. tumor necrosis factor and interferon-gamma. Furthermore, expression of mBD14 seems to be regulated by activation of the intracellular pattern recognition receptor NOD2/CARD15 as revealed by reporter gene analysis. We prepared a recombinant mBD14-Ig fusion protein that retained potent antimicrobial activity against several Escherichia coli strains but not against various Gram-positive Staphylococcus aureus strains. hBD3 and also the newly identified mBD14 were chemotactic for cells expressing the mouse CC-chemokine receptor CCR6. In addition, both hBD3 and mBD14 were chemotactic for freshly isolated mouse resident peritoneal cells. Thus, mBD14, based on structural and functional similarities, appears to be an orthologue of hBD3.
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Affiliation(s)
- Johann Röhrl
- Institute of Immunology University of Regensburg, D-93042 Regensburg, Germany
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208
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Hasegawa M, Fujimoto Y, Lucas PC, Nakano H, Fukase K, Núñez G, Inohara N. A critical role of RICK/RIP2 polyubiquitination in Nod-induced NF-kappaB activation. EMBO J 2007; 27:373-83. [PMID: 18079694 DOI: 10.1038/sj.emboj.7601962] [Citation(s) in RCA: 394] [Impact Index Per Article: 23.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2007] [Accepted: 11/23/2007] [Indexed: 01/01/2023] Open
Abstract
Nod1 and Nod2 are intracellular proteins that are involved in host recognition of specific bacterial molecules and are genetically associated with several inflammatory diseases. Nod1 and Nod2 stimulation activates NF-kappaB through RICK, a caspase-recruitment domain-containing kinase. However, the mechanism by which RICK activates NF-kappaB in response to Nod1 and Nod2 stimulation is unknown. Here we show that RICK is conjugated with lysine-63-linked polyubiquitin chains at lysine 209 (K209) located in its kinase domain upon Nod1 or Nod2 stimulation and by induced oligomerization of RICK. Polyubiquitination of RICK at K209 was essential for RICK-mediated IKK activation and cytokine/chemokine secretion. However, RICK polyubiquitination did not require the kinase activity of RICK or alter the interaction of RICK with NEMO, a regulatory subunit of IkappaB kinase (IKK). Instead, polyubiquitination of RICK was found to mediate the recruitment of TAK1, a kinase that was found to be essential for Nod1-induced signaling. Thus, RICK polyubiquitination links TAK1 to IKK complexes, a critical step in Nod1/Nod2-mediated NF-kappaB activation.
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Affiliation(s)
- Mizuho Hasegawa
- Department of Pathology, The University of Michigan Medical School, Ann Arbor, MI 48109, USA
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209
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Rogler G. The effects of NOD2/CARD15 mutations on the function of the intestinal barrier. J Crohns Colitis 2007; 1:53-60. [PMID: 21172185 DOI: 10.1016/j.crohns.2007.08.008] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/16/2007] [Accepted: 08/16/2007] [Indexed: 02/08/2023]
Abstract
NOD2 variants have been identified to be a susceptibility factor for Crohn's disease. The NOD2 protein is an intracellular sensor of the bacterial wall product muramyl dipeptide (MDP) and activates the transcription factor NF-kappaB upon MDP-binding. NOD2 variants are associated with reduced NF-kappaB activation and reduced production of epithelial derived antibacterial peptides such as defensins. A reduced expression of defensins is described and found in patients with Crohn's disease and ulcerative colitis especially when NOD2 variants are present. Furthermore recent evidence from mouse models suggests that the ability of intestinal epithelial cells to activate NF-kappaB upon bacterial stimulation protects from mucosal inflammation. Taken together these data indicate that NOD2 mediated NF-kappaB activation, subsequent induction of anti-microbial peptides such as defensins and induction of cytokine expression are essential for the function of the intestinal barrier and for the prevention of bacterial translocation. The data indicate why a defect in the induction of this acute defense response is associated with chronic inflammation. Invading bacteria that cannot be readily detected and eliminated may start a backup mechanism of inflammation finally resulting in chronic inflammatory reaction followed by further impairment of the mucosal barrier.
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Affiliation(s)
- Gerhard Rogler
- Clinic for Gastroenterology and Hepatology, Department of Internal Medicine, University Hospital Zürich, Rämistrasse 100, 8091 Zürich, Switzerland
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210
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Imanguli MM, Atkinson JC, Harvey KE, Hoehn GT, Ryu OH, Wu T, Kingman A, Barrett AJ, Bishop MR, Childs RW, Fowler DH, Pavletic SZ, Hart TC. Changes in salivary proteome following allogeneic hematopoietic stem cell transplantation. Exp Hematol 2007; 35:184-92. [PMID: 17258067 PMCID: PMC1832107 DOI: 10.1016/j.exphem.2006.10.009] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2006] [Revised: 10/18/2006] [Accepted: 10/18/2006] [Indexed: 11/27/2022]
Abstract
OBJECTIVE Allogeneic hematopoietic stem cell transplantation (allo-HCT) is frequently complicated by severe infections and graft-vs-host disease (GVHD). Saliva contains many components of adaptive and innate immune response crucial for local host defenses. Changes in salivary constituents could reflect systemic processes such as immune reconstitution and development of GVHD that occur posttransplant. This study was an initial evaluation of salivary protein changes that occur after allo-HCT. PATIENTS AND METHODS Serially collected saliva samples from 41 patients undergoing allo-HCT were evaluated. Changes in salivary proteome were initially examined by SELDI-TOF mass spectrometry. Individual protein changes were identified by 2-dimensional differential in-gel electrophoresis (2D-DIGE) with subsequent MS/MS sequencing and ELISA. RESULTS Significant increases and decreases in multiple salivary proteins that lasted at least 2 months posttransplant were detected by SELDI-TOF mass spectrometry. Lactoferrin and secretory leukocyte protease inhibitor demonstrated elevations 1 month post-HCT that persisted at least 6 months. Secretory IgA (sIgA) levels were decreased 1 month posttransplant, with recovery at approximately 6 months. Levels of salivary beta(2)-microglobulin were elevated at 6 months and correlated with sIgA levels. CONCLUSION Allo-HCT is associated with long-term changes in several salivary proteins important for innate immune responses. These results support further studies on the association of salivary proteins with posttransplant complications including infections and GVHD.
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Affiliation(s)
- Matin M Imanguli
- Clinical Research Core, National Institutes of Health, Bethesda, MD 20892, USA
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211
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Fritz JH, Le Bourhis L, Magalhaes JG, Philpott DJ. Innate immune recognition at the epithelial barrier drives adaptive immunity: APCs take the back seat. Trends Immunol 2007; 29:41-9. [PMID: 18054284 DOI: 10.1016/j.it.2007.10.002] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2007] [Revised: 10/29/2007] [Accepted: 10/29/2007] [Indexed: 01/07/2023]
Abstract
Innate immune recognition of microbe-associated molecular patterns by multiple families of pattern-recognition molecules such as Toll-like receptors and Nod-like receptors instructs the innate and adaptive immune system to protect the host from pathogens while also acting to establish a beneficial mutualism with commensal organisms. Although this task has been thought to be performed mainly by specialized antigen-presenting cells such as dendritic cells, recent observations point to the idea that innate immune recognition by stromal cells has important implications for the regulation of mucosal homeostasis as well as for the initiation of innate and adaptive immunity.
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Affiliation(s)
- Jörg H Fritz
- University of Toronto, Department of Immunology, Medical Sciences Building, 1 King's College Circle, Toronto, Ontario M5S 1A8, Canada
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212
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Chronic stimulation of Nod2 mediates tolerance to bacterial products. Proc Natl Acad Sci U S A 2007; 104:19440-5. [PMID: 18032608 DOI: 10.1073/pnas.0706097104] [Citation(s) in RCA: 206] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The Toll-like receptor (TLR) and nucleotide-binding oligomerization domain (Nod) families of proteins are critical for bacterial recognition, and, acutely, this frequently leads to proinflammatory responses. Polymorphisms in Nod2 (CARD 15) are associated with an increased likelihood of developing Crohn's disease. However, it is not yet clear how Nod2 dysfunctions lead to defects in human intestinal immune homeostasis. Studies to date have focused on functions after acute, rather than chronic, Nod2 stimulation. However, the intestine is an environment of chronic bacterial product exposure with tolerance to luminal flora. We therefore hypothesized that long-term Nod2 stimulation contributes to down-regulation of inflammatory responses from innate immune receptors. We found that pretreatment with muramyl dipeptide (MDP), a ligand for Nod2, significantly decreased production of the proinflammatory cytokines TNF-alpha, IL-8, and IL-1beta upon Nod2, TLR4, and TLR2 restimulation in primary human monocyte-derived macrophages from a large cohort of individuals. Importantly, TNF-alpha-induced production of proinflammatory cytokines remained intact in these same cells. MDP-stimulated macrophages from Crohn's disease-relevant Leu1007insC Nod2 homozygote individuals were deficient in their ability to cross-tolerize to subsequent treatment with TLR2 and TLR4 ligands. We show that acute Nod2 stimulation induced IRAK-1 activation, and that chronic MDP treatment down-regulated IRAK-1 activation upon Nod2 or TLR4 restimulation. In a subset of individuals, chronic Nod2 stimulation induced expression of the IRAK-1 inhibitory protein IRAK-M. Significantly, intestinal macrophages exhibit tolerance to MDP per production of inflammatory cytokines. These results illustrate a role for chronic stimulation of Nod2 in mediating tolerance to bacterial products.
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213
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El Mokhtari NE, Ott SJ, Nebel A, Schäfer A, Rosenstiel P, Förster M, Nothnagel M, Simon R, Schreiber S. Role of NOD2/CARD15 in coronary heart disease. BMC Genet 2007; 8:76. [PMID: 17980027 PMCID: PMC2204032 DOI: 10.1186/1471-2156-8-76] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2007] [Accepted: 11/02/2007] [Indexed: 01/07/2023] Open
Abstract
BACKGROUND Bacterial DNA has been repeatedly detected in atheromatous lesions of coronary heart disease (CHD) patients. Phylogenetic signatures in the atheroma lesions that are similar to those of bacterial biofilms on human barrier organs, including the respiratory or gastrointestinal tract, raise the question of a defective barrier function in CHD. NOD2 plays a major role in defense against bacterial invasion. Genetic variation in the CARD15 gene, which encodes NOD2, was previously shown to result in a barrier defect that causes chronic inflammatory disorders (e.g. Crohn disease). In the present study, we investigated the possible involvement of NOD2/CARD15 in the pathology of CHD by i) analyzing the local expression of NOD2 in atherectomy versus healthy tissue (n = 5 each) using histochemical immunofluorescence and ii) by testing the three major functional CARD15 variants (R702W, G908R and 1007fs) for association with early-onset CHD in 900 German patients and 632 healthy controls. RESULTS In atherectomy tissue of CHD patients, NOD2 was detected in inflammatory cells at the luminal sides of the lesions. However, the allele and genotype frequencies of the three major CARD15 polymorphisms did not differ between CHD patients and controls. CONCLUSION The NOD2 up-regulation in atheroma lesions indicates an involvement of this protein in the pathology of CHD. Although NOD2 could be important in local immune response mechanisms, none of the analyzed CARD15 variants seem to play a significant role in the etiology of CHD.
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214
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Kim JY, Omori E, Matsumoto K, Núñez G, Ninomiya-Tsuji J. TAK1 is a central mediator of NOD2 signaling in epidermal cells. J Biol Chem 2007; 283:137-144. [PMID: 17965022 DOI: 10.1074/jbc.m704746200] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Muramyl dipeptide (MDP) is a peptidoglycan moiety derived from commensal and pathogenic bacteria, and a ligand of its intracellular sensor NOD2. Mutations in NOD2 are highly associated with Crohn disease, which is characterized by dysregulated inflammation in the intestine. However, the mechanism linking abnormality of NOD2 signaling and inflammation has yet to be elucidated. Here we show that transforming growth factor beta-activated kinase 1 (TAK1) is an essential intermediate of NOD2 signaling. We found that TAK1 deletion completely abolished MDP-NOD2 signaling, activation of NF-kappaB and MAPKs, and subsequent induction of cytokines/chemokines in keratinocytes. NOD2 and its downstream effector RICK associated with and activated TAK1. TAK1 deficiency also abolished MDP-induced NOD2 expression. Because mice with epidermis-specific deletion of TAK1 develop severe inflammatory conditions, we propose that TAK1 and NOD2 signaling are important for maintaining normal homeostasis of the skin, and its ablation may impair the skin barrier function leading to inflammation.
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Affiliation(s)
- Jae-Young Kim
- Department of Environmental and Molecular Toxicology, North Carolina State University, Raleigh, North Carolina 27695
| | - Emily Omori
- Department of Environmental and Molecular Toxicology, North Carolina State University, Raleigh, North Carolina 27695
| | - Kunihiro Matsumoto
- Department of Molecular Biology, Graduate School of Science, Nagoya University, Nagoya, 464-8602 Japan; Solution Oriented Research for Science and Technology (SORST), Japan Science and Technology Agency, Japan
| | - Gabriel Núñez
- Department of Pathology and Comprehensive Cancer Center, University of Michigan, Ann Arbor, Michigan 48109
| | - Jun Ninomiya-Tsuji
- Department of Environmental and Molecular Toxicology, North Carolina State University, Raleigh, North Carolina 27695.
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215
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Werts C, le Bourhis L, Liu J, Magalhaes JG, Carneiro LA, Fritz JH, Stockinger S, Balloy V, Chignard M, Decker T, Philpott DJ, Ma X, Girardin SE. Nod1 and Nod2 induce CCL5/RANTES through the NF-kappaB pathway. Eur J Immunol 2007; 37:2499-508. [PMID: 17705131 DOI: 10.1002/eji.200737069] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The Nod-like receptor proteins Nod1 and Nod2 participate in innate immune responses against bacteria through intracellular detection of peptidoglycan, a component of bacterial cell wall. Recent evidence has demonstrated that Nod1 stimulates the release of chemokines that attract neutrophils at the site of infection, such as CXCL8/IL-8 in humans, and CXCL1/keratinocyte-derived chemokine and CXCL2/MIP-2 in mice. We aimed to determine whether Nod proteins could trigger the release of CCL5/RANTES, a chemokine known to attract a number of immune cells, but not neutrophils. Our results demonstrate that activation of both Nod1 and Nod2 results in substantial secretion of CCL5 by murine macrophages. Moreover, in vivo, the intraperitoneal injection of murine Nod1 or Nod2 agonists resulted in a rapid secretion of CCL5 into the bloodstream. We also observed that Nod-dependent secretion of CCL5 did not correlate with the induction of the interferon-beta pathway, a major signaling cascade for the activation of CCL5 by viruses. In contrast, we identified a key role of the NF-kappaB pathway in Nod-dependent stimulation of the CCL5 promoter. Together, these results identify a novel target downstream of Nod1 and Nod2, which is likely to play a key role in orchestrating the global Nod-dependent immune defense during bacterial infections.
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Affiliation(s)
- Catherine Werts
- Unité de Recherche Réponses Précoces aux Parasites et Immunopathologie, Institut Pasteur, Paris, France.
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216
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Carter J, Churchill AJ, Gorman C, Haynes R. A case of bilateral endophthalmitis and carriage of beta-defensin 1 44CC genotype. Br J Ophthalmol 2007; 91:1249-50. [PMID: 17709589 PMCID: PMC1954909 DOI: 10.1136/bjo.2006.111708] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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217
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Abstract
Defensins are antimicrobial peptides produced by professional phagocytes, Paneth cells, and intestinal epithelial cells. In addition to their potent antimicrobial activity, defensins can also modulate the function and movement of neutrophils, monocytes, T-lymphocytes, dendritic cells, and epithelial cells. Paneth cells are equipped with multiple defensins and antimicrobial proteins and usually reside in the small intestine. This review highlights the diverse functions of defensins and changes in defensin expression and Paneth cell proliferation in Crohn's disease, ulcerative colitis, and animal models of inflammatory bowel disease. Current data favor the hypothesis that defensins and Paneth cells may play important roles in the maintenance of intestinal immune homeostasis through 2 distinct mechanisms. The first mechanism is to act as effector molecules and cells against pathogenic microbes, while the second is to regulate host immune cell functions.
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Affiliation(s)
- Jishu Shi
- Department of Anatomy, Physiology and Pharmacology, Auburn University, Auburn, Alabama 36849, USA.
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218
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McGonagle D, Savic S, McDermott MF. The NLR network and the immunological disease continuum of adaptive and innate immune-mediated inflammation against self. Semin Immunopathol 2007; 29:303-13. [PMID: 17805542 DOI: 10.1007/s00281-007-0084-1] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2007] [Accepted: 07/09/2007] [Indexed: 12/31/2022]
Abstract
The nucleotide-binding domain, leucine-rich repeat containing family (NLR) network has provided pivotal genetic and molecular insights into diseases that were hitherto regarded as autoimmune. The NLR-related disorders include rare monogenic autoinflammatory diseases collectively termed cryopyrin-associated periodic syndromes, Crohn's disease which is a common polygenic disease and also an association at the mechanistic level with gout and pseudogout. Unlike the classical autoimmune diseases where disease immunopathogenesis is played out primarily in the primary and secondary lymphoid organs, the immunopathogenesis of the NLR-related disorders is played out in the tissues where inflammation arises. As the genetic mutations or molecular cascades associated with the NLR-related disorders have a widespread cellular distribution, it has been somewhat enigmatic why these disorders attack certain territories, but not others. This implies that tissue-specific factors in the target organs themselves contribute to disease expression. Such examples include the high abundance of NOD2 expressing cells in the part of the gut most typically afflicted by Crohn's disease and the preferential deposition of crystals in the joints to where inflammation localises in gout and pseudogout. The NLR network is associated principally with increases in TNF or IL-1 production, both of which are key players in innate immunity. Therefore, the NLR network identifies at the genetic and molecular level a robust paradigm for innate immune activation against self. This tissue-specific-factor-associated inflammation is the diametric opposite of classical autoimmunity. Of note, the MHC class-I-associated diseases including psoriasis (HLA-Cw6) and ankylosing spondylitis (HLA-B27) show striking clinical overlaps with Crohn's disease and also some rare monogenic diseases. Thus, the NLR innate immune pathway allows the full spectrum of inflammation against self to be viewed along an immunological disease continuum with autoantibody-associated disease at one end, innate immune diseases at the other and MHC class-1-related disorders as an intermediate.
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Affiliation(s)
- Dennis McGonagle
- The Leeds Institute of Molecular Medicine, Wellcome Trust Brenner Building, St James's University Hospital, The University of Leeds, Leeds, UK.
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219
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Menendez A, Brett Finlay B. Defensins in the immunology of bacterial infections. Curr Opin Immunol 2007; 19:385-91. [PMID: 17702560 DOI: 10.1016/j.coi.2007.06.008] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2007] [Revised: 06/15/2007] [Accepted: 06/29/2007] [Indexed: 12/31/2022]
Abstract
Defensins are a component of the host response against bacterial infections. Multiple studies suggest a linked upregulation of beta-defensins and pro-inflammatory cytokines expression in various tissues, as well as the possibility of mutual induction. Recent data demonstrate the importance of nucleotide-binding oligomerization proteins for the expression of defensins, and associate low levels of alpha-defensins expression by intestinal Paneth cells with susceptibility to Crohn's disease of the ileum. A novel anti-toxin activity has been identified for several alpha- and theta-defensins, expanding the repertoire of the antimicrobial functions of defensins. It has been shown that bacterial proteins can inactivate the action of defensins, and that pathogen type III secretion systems (T3SS) manipulate defensins expression via T3SS-mediated inhibition of the NF-kappaB pathway.
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Affiliation(s)
- Alfredo Menendez
- Michael Smith Laboratories, The University of British Columbia, 301-2185 East Mall, Vancouver, BC, Canada V6T 1Z4
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220
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Tattoli I, Travassos LH, Carneiro LA, Magalhaes JG, Girardin SE. The Nodosome: Nod1 and Nod2 control bacterial infections and inflammation. Semin Immunopathol 2007; 29:289-301. [PMID: 17690884 DOI: 10.1007/s00281-007-0083-2] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2007] [Accepted: 07/06/2007] [Indexed: 12/21/2022]
Abstract
Toll-like receptors (TLRs) and the nucleotide-binding domain, leucine rich repeat containing family (or Nod-like receptors, NLRs) are two important families of microbial sensors that are membrane-associated and cytosolic molecules, respectively. The Nod proteins Nod1 and Nod2 are two NLR family members that trigger immune defense in response to bacterial peptidoglycan. Nod proteins fight off bacterial infections by stimulating proinflammatory signaling and cytokine networks and by inducing antimicrobial effectors, such as nitric oxide and antimicrobial peptides. Nod1 is also critically implicated in shaping adaptive immune responses towards bacterial-derived constituents. In addition, recent evidence has demonstrated that mutations in Nod1 and Nod2 are associated with a number of human inflammatory disorders, including Crohn's disease, Blau syndrome, early-onset sarcoidosis, and atopic diseases. Together, Nod1 and Nod2 represent central players in the control of immune responses to bacterial infections and inflammation.
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Affiliation(s)
- Ivan Tattoli
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Medical Sciences Building, Toronto, ON, Canada
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221
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Ferwerda G, Kullberg BJ, de Jong DJ, Girardin SE, Langenberg DML, van Crevel R, Ottenhoff THM, Van der Meer JWM, Netea MG. Mycobacterium paratuberculosis is recognized by Toll-like receptors and NOD2. J Leukoc Biol 2007; 82:1011-8. [PMID: 17652449 DOI: 10.1189/jlb.0307147] [Citation(s) in RCA: 107] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Mycobacterium paratuberculosis has been suggested to be involved in the pathogenesis of Crohn's disease (CD). The importance of microorganisms in CD is supported by the association of CD with mutations in the intracellular pathogen recognition receptor (PRR) nucleotide-binding oligomerization domain 2 (NOD2). The aim of this study is to investigate the PRR involved in the recognition of M. paratuberculosis. Methods used include in vitro stimulation of transfected cell lines, murine macrophages, and human PBMC. M. paratuberculosis stimulated human TLR2 (hTLR2)-Chinese hamster ovary (CHO) cells predominantly and hTLR4-CHO cells modestly. Macrophages from TLR2 and TLR4 knockout mice produced less cytokines compared with controls after stimulation with M. paratuberculosis. TLR4 inhibition in human PBMC reduced cytokine production only after stimulation with live M. paratuberculosis. TLR-induced TNF-alpha, IL-1beta, and IL-10 production is mediated through MyD88, whereas Toll-IL-1R domain-containing adaptor inducing IFN-beta (TRIF) promoted the release of IL-1beta. hNOD2-human embryo kidney (HEK) cells, but not hNOD1-HEK cells, responded to stimulation with M. paratuberculosis. PBMC of individuals homozygous for the 3020insC NOD2 mutation showed a 70% defective cytokine response after stimulation with M. paratuberculosis. These results demonstrate that TLR2, TLR4, and NOD2 are involved in the recognition of M. paratuberculosis by the innate immune system.
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Affiliation(s)
- Gerben Ferwerda
- Department of Internal Medicine and Nijmegen University Center for Infectious Diseases, Radboud University Nijmegen Medical Center, Geert Grooteplein Zuid 8, 6525 GA Nijmegen, The Netherlands
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222
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Jones G. Susceptibility to asthma and eczema from mucosal and epidermal expression of distinctive genes. Curr Allergy Asthma Rep 2007; 7:11-7. [PMID: 17504656 DOI: 10.1007/s11882-007-0025-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The past several years have seen an increase in the rate at which genes that are associated with allergic asthma and eczema are discovered. This review -examines genetic association, gene expression, and functional studies that have identified genes that are expressed in the epithelial cells of the skin and lung and are involved in the pathogenesis of allergic asthma and eczema. This includes the genes encoding thymic stromal lympho-poietin (TSLP) and suppressor of cytokine signaling (SOCS3) that are involved in the activation of T-helper 2 cells, the microbial pattern recognition receptors nucleotide-binding oligomerization domain (NOD) genes (CARD4 and CARD15), Toll-like receptors (TLR2 and TLR4), and filaggrin, a protein required for effective barrier defense of the skin. Therefore, the development of allergic disease involves both the adaptive and innate immune systems, and the expression of these genes in the skin and lungs suggests a link to environmental -triggers at body surfaces.
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Affiliation(s)
- Graham Jones
- Institute for Immunology and Allergy Research, ICPMR Building, Westmead Hospital, Westmead, NSW, 2145, Australia.
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223
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Ferrero-Miliani L, Nielsen OH, Andersen PS, Girardin SE. Chronic inflammation: importance of NOD2 and NALP3 in interleukin-1beta generation. Clin Exp Immunol 2007; 147:227-35. [PMID: 17223962 PMCID: PMC1810472 DOI: 10.1111/j.1365-2249.2006.03261.x] [Citation(s) in RCA: 570] [Impact Index Per Article: 33.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Inflammation is part of the non-specific immune response that occurs in reaction to any type of bodily injury. In some disorders, the inflammatory process - which under normal conditions is self-limiting - becomes continuous and chronic inflammatory diseases might develop subsequently. Pattern recognition molecules (PRMs) represent a diverse collection of molecules responsible for sensing danger signals, and together with other immune components they are involved in the first line of defence. NALP3 and NOD2, which belong to a cytosolic subgroup of PRMs, dubbed Nod-like-receptors (NLRs), have been associated recently with inflammatory diseases, specifically Crohn's disease and Blau syndrome (NOD2) and familial cold autoinflammatory syndrome, Muckle-Wells syndrome and chronic infantile neurological cutaneous and articular syndrome (NALP3). The exact effects of the defective proteins are not fully understood, but activation of nuclear factor (NF)-kappaB, transcription, production and secretion of interleukin (IL)-1beta and activation of the inflammasome are some of the processes that might hold clues, and the present review will provide a thorough update in this area.
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Affiliation(s)
- L Ferrero-Miliani
- Department of Gastroenterology, Herlev Hospital, University of Copenhagen, Denmark.
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224
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Van Limbergen J, Russell RK, Nimmo ER, Ho GT, Arnott ID, Wilson DC, Satsangi J. Genetics of the innate immune response in inflammatory bowel disease. Inflamm Bowel Dis 2007; 13:338-55. [PMID: 17206667 DOI: 10.1002/ibd.20096] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The discovery of nucleotide-binding oligomerization domain 2/caspase recruitment domain-containing protein 15 (NOD2/CARD15) as the first susceptibility gene in Crohn's disease (CD) has shifted the focus of research into the pathogenesis of inflammatory bowel disease (IBD) firmly to the innate immune response and the integrity of the epithelial barrier. The subsequent implication in IBD of variant alleles of OCTN, DLG5, MDR1, and TLRs has provided further support for a new, more complex model of innate immunity function in the gastrointestinal tract. In this review, we examine the recent advances in our understanding of the influence of genetics of the innate immune response on IBD. We will focus on germline variation of genes encoding pathogen-recognition receptors, proteins involved in epithelial homeostasis and secreted antimicrobial proteins.
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Affiliation(s)
- Johan Van Limbergen
- Gastrointestinal Unit, Molecular Medicine Centre, University of Edinburgh, Western General Hospital, Crewe Road South, Edinburgh EH4 2XU, UK.
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225
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Lu X, Kurago Z, Brogden KA. Effects of polymicrobial communities on host immunity and response. FEMS Microbiol Lett 2007; 265:141-50. [PMID: 17081199 DOI: 10.1111/j.1574-6968.2006.00485.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Microorganisms grow as members of microbial communities in unique niches, such as the mucosal surfaces of the human body. These microbial communities, containing both commensals and opportunistic pathogens, serve to keep individual pathogens 'in check' through a variety of mechanisms and complex interactions, both between the microorganisms themselves and the microorganisms and the host. Recent studies shed new light on the diversity of microorganisms that form the human microbial communities and the interactions these microbial communities have with the host to stimulate immune responses. This occurs through their recognition by dendritic cells or their ability to induce differential cytokine and defensin profiles. The differential induction of defensins by commensals and pathogens and the ability of the induced defensins to interact with the antigens from these microorganisms may attenuate proinflammatory signaling and trigger adaptive immune responses to microbial antigens in a multistep process. Such an activity may be a mechanism that the host uses to sense what is on its mucosal surfaces, as well as to differentiate among commensals and pathogens.
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Affiliation(s)
- Xiaoying Lu
- Department of Periodontics and Dows Institute for Dental Research, N401, College of Dentistry, The University of Iowa, Iowa City, IA 52242, USA
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226
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Keller MJ, Guzman E, Hazrati E, Kasowitz A, Cheshenko N, Wallenstein S, Cole AL, Cole AM, Profy AT, Wira CR, Hogarty K, Herold BC. PRO 2000 elicits a decline in genital tract immune mediators without compromising intrinsic antimicrobial activity. AIDS 2007; 21:467-76. [PMID: 17301565 DOI: 10.1097/qad.0b013e328013d9b5] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
OBJECTIVE Vaginal microbicides should protect against infection without disrupting the mucosal environment or its mediators of host defense. The objective of this study was to examine the effect of 14 daily applications of 0.5% PRO 2000 or placebo gel on mediators of mucosal immunity and intrinsic antimicrobial activity. DESIGN AND METHODS A randomized, prospective, double-blind, placebo-controlled study was conducted among 24 healthy, abstinent women. Levels of cytokines, chemokines, defensins, and other protective factors and intrinsic antimicrobial activity were determined in cervicovaginal lavage samples collected on study days 0, 7, 14, and 21. RESULTS No increase in pro-inflammatory cytokines was observed. Rather cytokines and protective factors including interleukin (IL)-1 receptor antagonist, immunoglobulins and human beta-defensin 2 were lower in the drug compared with the placebo group. All of the mediators returned towards baseline on day 21. Women who were cycling had lower levels of most proteins on study days 7 and/or 14 compared with women on oral contraceptives; however, the magnitude of decline was greater in women who received PRO 2000 compared with placebo gel. The reduction in protective factors was not associated with a loss in the intrinsic anti-viral (HIV or herpes simplex virus) activity or anti-bacterial activity (Escherichia coli or Staphylococcus aureus). CONCLUSION In contrast to experience with nonoxynol-9, PRO 2000 did not trigger an inflammatory response in cervicovaginal secretions. There was a modest reduction in mucosal immune mediators, but this loss was not associated with a reduction in intrinsic antimicrobial activity.
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Affiliation(s)
- Marla J Keller
- Department of Medicine, Mount Sinai School of Medicine, New York, New York 10029, USA
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227
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Schlee M, Wehkamp J, Altenhoefer A, Oelschlaeger TA, Stange EF, Fellermann K. Induction of human beta-defensin 2 by the probiotic Escherichia coli Nissle 1917 is mediated through flagellin. Infect Immun 2007; 75:2399-407. [PMID: 17283097 PMCID: PMC1865783 DOI: 10.1128/iai.01563-06] [Citation(s) in RCA: 221] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Human beta-defensin 2 (hBD-2) is an inducible antimicrobial peptide synthesized by the epithelium to counteract bacterial adherence and invasion. Proinflammatory cytokines, as well as certain bacterial strains, have been identified as potent endogenous inducers. Recently, we have found that hBD-2 induction by probiotic Escherichia coli Nissle 1917 was mediated through NF-kappaB- and AP-1-dependent pathways. The aim of the present study was to identify the responsible bacterial factor. E. coli Nissle 1917 culture supernatant was found to be more potent than the pellet, indicating a soluble or shed factor. Chemical analysis demonstrated the factor to be heat resistant and proteinase digestible. Several E. coli Nissle 1917 deletion mutants were constructed and tested for their ability to induce hBD-2 expression in Caco-2 cells. Deletion mutants for flagellin specifically exhibited an impaired immunostimulatory capacity. Reinsertion of the flagellin gene restored the induction capacity to normal levels. Isolated flagellin from E. coli Nissle 1917 and from Salmonella enterica serovar Enteritidis induced hBD-2 mRNA significantly in contrast to the flagellin of the apathogenic E. coli strain ATCC 25922. H1 flagellin antiserum abrogated hBD-2 expression induced by flagellin as well as E. coli Nissle 1917 supernatant, confirming that flagellin is the major stimulatory factor of E. coli Nissle 1917.
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Affiliation(s)
- Miriam Schlee
- Dr. Margarete Fischer Bosch Institute of Clinical Pharmacology, Stuttgart, Germany
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228
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Abstract
Research into intracellular sensing of microbial products is an up and coming field in innate immunity. Nod1 and Nod2 are members of the rapidly expanding family of NACHT domain-containing proteins involved in intracellular recognition of bacterial products. Nods proteins are involved in the cytosolic detection of peptidoglycan motifs of bacteria, recognized through the LRR domain. The role of the NACHT-LRR system of detection in innate immune responses is highlighted at the mucosal barrier, where most of the membranous Toll like receptors (TLRs) are not expressed, or with pathogens that have devised ways to escape TLR sensing. For a given pathogen, the sum of the pathways induced by the recognition of the different "pathogen associated molecular patterns" (PAMPs) by the different pattern recognition receptors (PRRs) trigger and shape the subsequent innate and adaptive immune responses. Knowledge gathered during the last decade on PRR and their agonists, and recent studies on bacterial infections provide new insights into the immune response and the pathogenesis of human infectious diseases.
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Affiliation(s)
- Lionel Le Bourhis
- Innate Immunity and Signalisation, Institut Pasteur, 28, Rue du Dr. Roux, 75724 Paris Cedex 15, France
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229
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Abstract
PURPOSE OF REVIEW This review describes recent progress in our understanding of defensins and their contributions to innate immunity. Defensins are small, cysteine-rich endogenous antibiotic peptides. Human neutrophils contain large amounts of three alpha-defensins (HNP-1-HNP-3), and smaller amounts of a fourth, HNP-4. Monocytes and macrophages generally lack defensins, but they release messengers that induce the synthesis of beta-defensins in epithelial cells. RECENT FINDINGS In addition to their antimicrobial and immunomodulatory effects, HNP-1-HNP-3 possess antiviral and toxin-neutralizing properties. Induction of beta-defensins in epithelial cells is mediated by cell-surface Toll-like receptors or cytoplasmic peptidoglycan receptors that can recognize pathogen-associated molecules. Mutations in Nod2, a cytoplasmic peptidoglycan receptor, are associated with reduced levels of intestinal alpha-defensins and ileal Crohn's disease. Human defensin genes show marked copy-number polymorphism. High level constitutive expression of defensins may afford protection against HIV-1 and other defensin-sensitive pathogens. Theta-defensins (cyclic octadecapeptides found in nonhuman primates) have impressive antiviral and antitoxic properties. SUMMARY The multiple properties of defensins contribute to human innate immunity against bacteria, bacterial toxins, and viruses.
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Affiliation(s)
- Robert I Lehrer
- David Geffen School of Medicine at UCLA, Los Angeles, California 90095, USA.
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230
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Hazrati E, Galen B, Lu W, Wang W, Ouyang Y, Keller MJ, Lehrer RI, Herold BC. Human α- and β-Defensins Block Multiple Steps in Herpes Simplex Virus Infection. THE JOURNAL OF IMMUNOLOGY 2006; 177:8658-66. [PMID: 17142766 DOI: 10.4049/jimmunol.177.12.8658] [Citation(s) in RCA: 193] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
This study examined the ability of nine human defensins (HD) to protect against herpes simplex virus infection. Noncytotoxic concentrations of all six alpha-defensins (HNP1-4, HD5, and HD6) and human beta-defensin (hBD) 3 inhibited HSV infection. Two other beta-defensins, hBD1 and 2, lacked this protective activity. Synchronized assays revealed that HNP-4, HD6, and hBD3 acted primarily by preventing binding and entry, whereas HNP1-3 and HD5 also inhibited postentry events. Even when added several hours after entry, substantial reduction in viral gene expression ensued. Human cervical epithelial cells incubated with HNP-1 or HD5 accumulated the peptides intracellularly. Surface plasmon resonance studies revealed that HNPs 1, 2, 3, and HD5 bound HSV glycoprotein B (gB) with high affinity, but showed minimal binding to heparan sulfate, the receptor for attachment. In contrast, HNP-4 and HD6 bound heparan sulfate, but not gB. HBD3 bound both gB and heparan sulfate, but hBD1 and hBD2 bound neither. Admixture of HD5 with hydroxyethylcellulose significantly protected mice from a viral challenge lethal to controls receiving an inactive peptide or hydroxyethylcellulose alone. These findings demonstrate that HDs act at multiple steps in the HSV life cycle and support the development of defensins or defensin-like peptides as microbicides.
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Affiliation(s)
- Ehsan Hazrati
- Department of Pediatrics, Mount Sinai School of Medicine, 1 Gustave L. Levy Place, New York, NY 10029, USA
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231
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Abstract
PURPOSE OF REVIEW Inflammatory bowel disease is thought to result from an abnormal response to the gut microbiota. This review discusses advances in knowledge of the changes in gut microbiota and host response in inflammatory bowel disease. RECENT FINDINGS Approximately 15% of Crohn's disease cases in western populations result from mutations in NOD2/CARD15. This disease leads to defective intestinal defensin production and defective monocyte interleukin-8 response to bacterial peptidoglycan. A similar defective interleukin-8 response and consequent delayed neutrophil recruitment have also been shown in patients with Crohn's disease who do not have the NOD2 mutation. A consequence seems to be the accumulation in tissue of macrophages containing various bacteria, perhaps particularly Escherichia coli. In keeping with this patients with Crohn's disease have circulating antibodies against bacterial flagellar proteins of enterobacteria and clostridia. In ulcerative colitis, there is less evidence for invasion by or immune response to bacteria but changes in gut microbiota include a relative deficiency of bifidobacteria. There is considerable interest in probiotic or prebiotic therapies although so far little evidence for their efficacy. SUMMARY Molecular techniques are giving us better insight into the gut microbiota in inflammatory bowel disease that should translate into improved therapies.
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Affiliation(s)
- Sreedhar Subramanian
- Division of Gastroenterology, School of Clinical Sciences, University of Liverpool, Liverpool, UK
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232
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Abstract
PURPOSE OF REVIEW To review recently published studies presenting novel and relevant information on Paneth cells and their function. RECENT FINDINGS Paneth cells are secretory epithelial cells which are predominantly found in the small-intestinal crypts of Lieberkühn. Their most abundant products are alpha-defensins, which are endogenous antibiotics with activity against gram-negative and gram-positive bacteria, fungi, viruses and protozoa. The differentiation from stem-cell progenitors to Paneth cells is regulated by Wnt signalling via a complex gene programme, terminally including defensins. A disturbance of Paneth-cell differentiation and function may predispose to intestinal infections and appears to be a critical factor in the pathogenesis of ileal Crohn's disease, an inflammatory disease of the intestinal tract. SUMMARY It is conceivable that these recent findings together with a better understanding of underlying mechanisms involved in the regulation and biology of Paneth cells will open up new therapeutic avenues for preventing infection as well as for causally treating inflammatory bowel diseases.
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Affiliation(s)
- Jan Wehkamp
- Robert Bosch Hospital and Dr Margarete Fischer-Bosch Institute of Clinical Pharmacology, Stuttgart, Germany.
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233
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Franchi L, McDonald C, Kanneganti TD, Amer A, Núñez G. Nucleotide-binding oligomerization domain-like receptors: intracellular pattern recognition molecules for pathogen detection and host defense. THE JOURNAL OF IMMUNOLOGY 2006; 177:3507-13. [PMID: 16951308 DOI: 10.4049/jimmunol.177.6.3507] [Citation(s) in RCA: 108] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The nucleotide binding oligomerization domain-like receptor (NLR) family of pattern recognition molecules is involved in a diverse array of processes required for host immune responses against invading pathogens. Unlike TLRs that mediate extracellular recognition of microbes, several NLRs sense pathogens in the cytosol and upon activation induce host defense signaling pathways. Although TLRs and NLRs differ in their mode of pathogen recognition and function, they share similar domains for microbial sensing and cooperate to elicit immune responses against the pathogen. Genetic variation in several NLR genes is associated with the development of inflammatory disorders or increased susceptibility to microbial infection. Further understanding of NLRs should provide critical insight into the mechanisms of host defense and the pathogenesis of inflammatory diseases.
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Affiliation(s)
- Luigi Franchi
- Department of Pathology and Comprehensive Cancer Center, University of Michigan Medical School, Ann Arbor, MI 48109, USA
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234
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Peyrin-Biroulet L, Vignal C, Dessein R, Simonet M, Desreumaux P, Chamaillard M. NODs in defence: from vulnerable antimicrobial peptides to chronic inflammation. Trends Microbiol 2006; 14:432-8. [PMID: 16942880 DOI: 10.1016/j.tim.2006.08.008] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2006] [Revised: 07/28/2006] [Accepted: 08/15/2006] [Indexed: 12/24/2022]
Abstract
Defensins and cathelicidins are prevalent and essential gastrointestinal cationic antimicrobial peptides (CAPs). However, these defensive peptides are not infallible because certain enteropathogens can overcome their protective function. Furthermore, impaired defensin synthesis has been linked to the occurrence of Crohn's disease (CD), a chronic inflammatory bowel disease. Recently, defective bacterial sensing through NOD1 and NOD2 has been related to reduced defensin production, CD predisposition and susceptibility to enteric infection. Hence, we propose that microbial sensors at the gut interface monitor the levels of these effector peptides, which might function as "danger" signals to confer tolerance and alert immunocytes. Further work is required to clarify how gastrointestinal CAPs are regulated and to assess their role in maintaining epithelial homeostasis and triggering adaptive immunity.
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Affiliation(s)
- Laurent Peyrin-Biroulet
- INSERM U795, University of Lille 2, Huriez Hospital, Digestive Tract Diseases and Nutrition Department, F-59037 Lille, France
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235
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Menzies BE, Kenoyer A. Signal transduction and nuclear responses in Staphylococcus aureus-induced expression of human beta-defensin 3 in skin keratinocytes. Infect Immun 2006; 74:6847-54. [PMID: 16954397 PMCID: PMC1698080 DOI: 10.1128/iai.00389-06] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The human beta-defensin 3 (hBD-3) is an inducible epithelial peptide antibiotic that has potent antistaphylococcal activity. Infection of skin epithelial cells with viable Staphylococcus aureus, a common skin pathogen, induces increased gene expression of hBD-3 and other antimicrobial peptides. The aim of this study was to identify signaling pathways and nuclear responses that contribute to the gene expression of hBD-3 in primary human keratinocytes upon contact with S. aureus. Increased hBD-3 peptide was observed by immunofluorescence microscopy in keratinocytes exposed to S. aureus and to lipoteichoic acid (LTA). Both are ligands for the cell surface Toll-like receptor 2 (TLR2), and thus the contribution of TLR2 signaling in hBD-3 expression was examined. Functional inhibition of TLR2 prior to S. aureus stimulation significantly decreased hBD-3 mRNA levels by 37%, attesting to the involvement of this surface receptor in the initial recognition and downstream signaling for hBD-3 expression. Treatment of keratinocytes with a p38 mitogen-activated protein kinase (MAPK) inhibitor prior to either S. aureus or LTA stimulation was associated with reduced hBD-3 mRNA transcripts and peptide. We also propose a role for the MAPK-regulated transcriptional activating protein 1 in S. aureus-induced hBD-3 gene expression. Combined, these studies indicate a role for TLR2 signaling and MAPK activation in the upregulation of hBD-3 and demonstrate the innate immune capacity of skin keratinocytes under conditions of S. aureus challenge to enhance the local expression of this antistaphylococcal peptide antibiotic.
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Affiliation(s)
- Barbara E Menzies
- Department of Veterans Affairs S-111-ID, Puget Sound Health Care System, 1660 S. Columbian Way, Seattle, WA 98108, USA.
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236
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Abstract
Inflammatory bowel diseases, ulcerative colitis, and Crohn’s disease, are chronic intestinal disorders of unknown etiology in which in genetically susceptible individuals, the mucosal immune system shows an aberrant response towards commensal bacteria. The gastrointestinal tract has developed ingenious mechanisms to coexist with its autologous microflora, but rapidly responds to invading pathogens and then returns to homeostasis with its commensal bacteria after the pathogenic infection is cleared. In case of disruption of this tightly-regulated homeostasis, chronic intestinal inflammation may be induced. Previous studies showed that some commensal bacteria are detrimental while others have either no influence or have a protective action. In addition, each host has a genetically determined response to detrimental and protective bacterial species. These suggest that therapeutic manipulation of imbalance of microflora can influence health and disease. This review focuses on new insights into the role of commensal bacteria in gut health and disease, and presents recent findings in innate and adaptive immune interactions. Therapeutic approaches to modulate balance of intestinal microflora and their potential mechanisms of action are also discussed.
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Affiliation(s)
- Akira Andoh
- Department of Internal Medicine, Shiga University of Medical Science, Seta Tukinowa, Otsu 520-2192, Japan.
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237
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Abstract
Polymorphisms in NOD2 (CARD15) are associated with ileal and ileocolonic Crohn's disease, increased mortality from graft-versus-host disease, and Blau syndrome. NOD2 activation by peptidoglycan components initiates various signaling pathways and CD-associated NOD2 mutations are associated with decreased activation of NF-kappaB. NOD2 may be important for both initial defenses against commensal and pathogenic bacteria and tolerance mechanisms for maintaining controlled activation of the intestinal immune system. Significant progress has been made in defining NOD2 signaling partners and pathways and functional consequences of NOD2 mutations with respect to its activation, expression, signaling, synergistic effects with Toll-like receptor signaling, and antimicrobial effects. However, NOD2 contributions to human intestinal inflammation are complex and incompletely understood. Improved understanding of NOD2-mediated pathways may lead to identification of other molecules that can also contribute to the development of Crohn's disease in humans.
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Affiliation(s)
- Clara Abraham
- Department of Medicine, Section of Gastroenterology, University of Chicago, Chicago, Illinois 60637, USA.
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238
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Abstract
Recent advances in the field of inflammatory bowel disease (IBD) genetics have enabled the definition and refinement of multiple IBD susceptibility loci and the identification of gene variants within such regions showing association with Crohn's disease (CD) and/or ulcerative colitis (UC). Most notable among the newly defined genetic determinants of IBD are specific variants in the CARD15 gene, which have been shown widely to influence both susceptibility and phenotype in CD. These genetic data have inspired intensive studies of CARD15 biologic functions and the information emerging from these analyses has already substantively enhanced understanding of the signaling pathways coupling bacterial pathogens to the host immune response. Genetic data implicating various other signaling effectors in IBD susceptibility have similarly focused attention on the molecular pathways driven or regulated by these proteins and the biochemical events linking effector/pathway dysfunction to intestinal inflammation and disease. In this review, progress in defining the genetic determinants of IBD is described with an emphasis on the impact of such knowledge on understanding of IBD molecular pathophysiology.
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Affiliation(s)
- Katherine Anne Siminovitch
- Department of Medicine, University of Toronto, Mount Sinai Hospital Samuel Lunenfeld and Toronto General Hospital Research Institutes, 600 University Avenue, Room 778D, Toronto, Ont., Canada M5G 1X5.
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