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Randhawa AK, Hawn TR. Toll-like receptors: their roles in bacterial recognition and respiratory infections. Expert Rev Anti Infect Ther 2008; 6:479-95. [PMID: 18662115 DOI: 10.1586/14787210.6.4.479] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Although respiratory infections cause significant morbidity and mortality throughout the world, the immunologic factors that mediate host susceptibility to these infections remain poorly understood. The lung contains a vast surface at the host-environment interface and acts as a crucial barrier to invading pathogens. The lung is equipped with specialized epithelial and hematopoietic cells, which express pattern recognition receptors that act as both sentinels and mediators of pulmonary innate immunity. Toll-like receptors (TLRs) mediate a particularly critical role in pathogen recognition and subsequent initiation of the host immune response. In this review, we will summarize current knowledge of TLRs and their bacterial ligands and explore their role in respiratory infections. Moreover, we will highlight recent advances in the role of TLRs in pulmonary infections from a human immunogenetics perspective.
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Affiliation(s)
- April Kaur Randhawa
- Department of Medicine/Division of Allergy & Infections Diseases, University of Washington School of Medicine, 1959 NE Pacific Street, Seattle, WA 98195, USA.
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102
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103
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El Chamy L, Leclerc V, Caldelari I, Reichhart JM. Sensing of 'danger signals' and pathogen-associated molecular patterns defines binary signaling pathways 'upstream' of Toll. Nat Immunol 2008; 9:1165-70. [PMID: 18724373 PMCID: PMC2768518 DOI: 10.1038/ni.1643] [Citation(s) in RCA: 149] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2008] [Accepted: 07/11/2008] [Indexed: 11/09/2022]
Abstract
In drosophila, molecular determinants from fungi and Gram-positive bacteria are detected by circulating pattern-recognition receptors. Published findings suggest that such pattern-recognition receptors activate as-yet-unidentified serine-protease cascades that culminate in the cleavage of Spätzle, the endogenous Toll receptor ligand, and trigger the immune response. We demonstrate here that the protease Grass defines a common activation cascade for the detection of fungi and Gram-positive bacteria mediated by pattern-recognition receptors. The serine protease Persephone, shown before to be specific for fungal detection in a cascade activated by secreted fungal proteases, was also required for the sensing of proteases elicited by bacteria in the hemolymph. Hence, Persephone defines a parallel proteolytic cascade activated by 'danger signals' such as abnormal proteolytic activities.
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Affiliation(s)
- Laure El Chamy
- Institut de Biologie Moléculaire et Cellulaire, Centre National de la Recherche Scientifique Unité Propre de Recherche 9022, Université Louis Pasteur, Strasbourg Cedex, France
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104
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Angiotensin-converting enzyme limits inflammation elicited by Trypanosoma cruzicysteine proteases: a peripheral mechanism regulating adaptive immunity via the innate kinin pathway. Biol Chem 2008. [DOI: 10.1515/bc.2008.126_bchm.just-accepted] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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105
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Abstract
PURPOSE OF REVIEW Over the last 2 decades, studies addressing mechanisms of type 1 diabetes have focused primarily on the role of T lymphocytes in disease mechanisms. Recent investigations, however, suggest that the innate immune system plays a key role in promoting the response of autoreactive T cells triggering type 1 diabetes. The discovery of toll-like receptors in the 1990s has led to a better understanding of signaling pathways involved in initiating innate immune pathways and how these pathways may be associated with mechanisms leading to autoimmune disease. This review focuses on recent studies on the role of Toll-like receptors and innate pathways in triggering type 1 diabetes. RECENT FINDINGS Data from animal models of type 1 diabetes provide strong support to the hypothesis that Toll-like receptor-induced innate signaling pathways are involved in the proinflammatory process leading to autoimmune diabetes. Studies performed in peripheral blood cells and sera from patients with type 1 diabetes indicate that aberrant innate functions might exist in such patients, but the relevance of these alterations to the mechanism leading to type 1 diabetes is currently unclear. SUMMARY The discovery that innate signaling pathways are involved in the mechanism that may trigger islet inflammation and destruction holds great promise for the identification of new innate signaling molecules that could be targeted to specifically inhibit the autoimmune process to prevent autoimmune diabetes.
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Affiliation(s)
- Danny Zipris
- Department of Pediatrics, Barbara Davis Center for Childhood Diabetes, University of Colorado, Aurora, Colorado 80045-6511, USA.
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106
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Rallabhandi P, Nhu QM, Toshchakov VY, Piao W, Medvedev AE, Hollenberg MD, Fasano A, Vogel SN. Analysis of proteinase-activated receptor 2 and TLR4 signal transduction: a novel paradigm for receptor cooperativity. J Biol Chem 2008; 283:24314-25. [PMID: 18622013 DOI: 10.1074/jbc.m804800200] [Citation(s) in RCA: 110] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Proteinase-activated receptor 2 (PAR2), a seven-transmembrane G protein-coupled receptor, is activated at inflammatory sites by proteolytic cleavage of its extracellular N terminus by trypsin-like enzymes, exposing a tethered, receptor-activating ligand. Synthetic agonist peptides (AP) that share the tethered ligand sequence also activate PAR2, often measured by Ca2+ release. PAR2 contributes to inflammation through activation of NF-kappaB-regulated genes; however, the mechanism by which this occurs is unknown. Overexpression of human PAR2 in HEK293T cells resulted in concentration-dependent, PAR2 AP-inducible NF-kappaB reporter activation that was protein synthesis-independent, yet blocked by inhibitors that uncouple Gi proteins or sequester intracellular Ca2+. Because previous studies described synergistic PAR2- and TLR4-mediated cytokine production, we hypothesized that PAR2 and TLR4 might interact at the level of signaling. In the absence of TLR4, PAR2-induced NF-kappaB activity was inhibited by dominant negative (DN)-TRIF or DN-TRAM constructs, but not by DN-MyD88, findings confirmed using cell-permeable, adapter-specific BB loop blocking peptides. Co-expression of TLR4/MD-2/CD14 with PAR2 in HEK293T cells led to a synergistic increase in AP-induced NF-kappaB signaling that was MyD88-dependent and required a functional TLR4, despite the fact that AP exhibited no TLR4 agonist activity. Co-immunoprecipitation of PAR2 and TLR4 revealed a physical association that was AP-dependent. The response to AP or lipopolysaccharide was significantly diminished in TLR4(-/-) and PAR2(-/-) macrophages, respectively, and SW620 colonic epithelial cells exhibited synergistic responses to co-stimulation with AP and lipopolysaccharide. Our data suggest a unique interaction between two distinct innate immune response receptors and support a novel paradigm of receptor cooperativity in inflammatory responses.
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Affiliation(s)
- Prasad Rallabhandi
- Department of Microbiology and Immunology, University of Maryland, Baltimore, Maryland 21201, USA
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107
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TLR-4 deficiency protects against focal cerebral ischemia and axotomy-induced neurodegeneration. Neurobiol Dis 2008; 31:33-40. [DOI: 10.1016/j.nbd.2008.03.002] [Citation(s) in RCA: 133] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2007] [Revised: 02/29/2008] [Accepted: 03/13/2008] [Indexed: 01/02/2023] Open
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108
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Melican K, Boekel J, Månsson LE, Sandoval RM, Tanner GA, Källskog O, Palm F, Molitoris BA, Richter-Dahlfors A. Bacterial infection-mediated mucosal signalling induces local renal ischaemia as a defence against sepsis. Cell Microbiol 2008; 10:1987-98. [PMID: 18549455 DOI: 10.1111/j.1462-5822.2008.01182.x] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Ascending urinary tract infections can cause extensive damage to kidney structure and function. We have used a number of advanced techniques including multiphoton microscopy to investigate the crucial early phases of uropathogenic Escherichia coli induced pyelonephritis within a living animal. Our results reveal a previously undescribed innate vascular response to mucosal infection, allowing isolation and eradication of the pathogen. The extremely rapid host response to mucosal infection was highlighted by the triggering of a cascade of events within 3-4 h. Epithelial signalling produced an increase in cellular O(2) consumption and affected microvascular flow by clotting, causing localized ischaemia. Subsequent ischaemic damage affected pathophysiology with actin re-arrangement and epithelial sloughing leading to paracellular bacterial movement. A denuded tubular basement membrane is shown to hinder immediate dissemination of bacteria, giving the host time to isolate the infection by clotting. Suppression of clotting by heparin treatment caused fatal urosepsis. Clinically these findings may be relevant in antibiotics delivery in pyelonephritis patients and to the use of anticoagulants in sepsis.
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Affiliation(s)
- Keira Melican
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
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109
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Ulanova M, Gravelle S, Barnes R. The role of epithelial integrin receptors in recognition of pulmonary pathogens. J Innate Immun 2008; 1:4-17. [PMID: 20375562 PMCID: PMC7190199 DOI: 10.1159/000141865] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2008] [Accepted: 04/30/2008] [Indexed: 12/19/2022] Open
Abstract
Integrins are a large family of heterodimeric transmembrane cell adhesion receptors. During the last decade, it has become clear that integrins significantly participate in various host-pathogen interactions involving pathogenic bacteria, fungi, and viruses. Many bacteria possess adhesins that can bind either directly or indirectly to integrins. However, there appears to be an emerging role for integrins beyond simply adhesion molecules. Given the conserved nature of integrin structure and function, and the diversity of the pathogens which use integrins, it appears that they may act as pattern recognition receptors important for the innate immune response. Several clinically significant bacterial pathogens target lung epithelial integrins, and this review will focus on exploring various structures and mechanisms involved in these interactions.
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Affiliation(s)
- Marina Ulanova
- Northern Ontario School of Medicine, Lakehead University, Thunder Bay, Ont., Canada.
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110
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Huang S, Yuan S, Guo L, Yu Y, Li J, Wu T, Liu T, Yang M, Wu K, Liu H, Ge J, Yu Y, Huang H, Dong M, Yu C, Chen S, Xu A. Genomic analysis of the immune gene repertoire of amphioxus reveals extraordinary innate complexity and diversity. Genome Res 2008; 18:1112-26. [PMID: 18562681 DOI: 10.1101/gr.069674.107] [Citation(s) in RCA: 287] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
It has been speculated that before vertebrates evolved somatic diversity-based adaptive immunity, the germline-encoded diversity of innate immunity may have been more developed. Amphioxus occupies the basal position of the chordate phylum and hence is an important reference to the evolution of vertebrate immunity. Here we report the first comprehensive genomic survey of the immune gene repertoire of the amphioxus Branchiostoma floridae. It has been reported that the purple sea urchin has a vastly expanded innate receptor repertoire not previously seen in other species, which includes 222 toll-like receptors (TLRs), 203 NOD/NALP-like receptors (NLRs), and 218 scavenger receptors (SRs). We discovered that the amphioxus genome contains comparable expansion with 71 TLR gene models, 118 NLR models, and 270 SR models. Amphioxus also expands other receptor-like families, including 1215 C-type lectin models, 240 LRR and IGcam-containing models, 1363 other LRR-containing models, 75 C1q-like models, 98 ficolin-like models, and hundreds of models containing complement-related domains. The expansion is not restricted to receptors but is likely to extend to intermediate signal transducers because there are 58 TIR adapter-like models, 36 TRAF models, 44 initiator caspase models, and 541 death-fold domain-containing models in the genome. Amphioxus also has a sophisticated TNF system and a complicated complement system not previously seen in other invertebrates. Besides the increase of gene number, domain combinations of immune proteins are also increased. Altogether, this survey suggests that the amphioxus, a species without vertebrate-type adaptive immunity, holds extraordinary innate complexity and diversity.
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Affiliation(s)
- Shengfeng Huang
- State Key Laboratory of Biocontrol, Guangdong Key Laboratory of Pharmaceutical Functional Genes, College of Life Sciences, Sun Yat-sen (Zhongshan) University, Guangzhou 510275, People's Republic of China
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111
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Nox enzymes and oxidative stress in the immunopathology of the gastrointestinal tract. Semin Immunopathol 2008; 30:315-27. [PMID: 18521607 DOI: 10.1007/s00281-008-0124-5] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2008] [Accepted: 05/08/2008] [Indexed: 02/07/2023]
Abstract
Chronic inflammation caused by Helicobacter pylori infection or inflammatory bowel disease (IBD) is closely linked to cancer development. Innate immune abnormalities and enhanced production of reactive oxygen species through a phagocyte NADPH oxidase (Nox2) are key issues in understanding the pathogenesis of inflammation-dependent carcinogenesis. Besides Nox2, functionally distinct homologues (Nox1, Nox3, Nox4, Nox5, Duox1, and Duox2) have been identified. Nox1 and Duox2 are highly expressed in the gastrointestinal tract. Although the functional roles of Nox/Duox in the gastrointestinal tract are still unclear, we will review their potential roles in the gastrointestinal immunopathology, particularly in H. pylori-induced inflammation, IBD, and malignancy.
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112
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113
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Schmidt RL, Trejo TR, Plummer TB, Platt JL, Tang AH. Infection-induced proteolysis of PGRP-LC controls the IMD activation and melanization cascades in Drosophila. FASEB J 2008; 22:918-29. [PMID: 18308747 DOI: 10.1096/fj.06-7907com] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The Drosophila immune deficiency (IMD) pathway, homologous to the mammalian tumor necrosis factor (TNF-alpha) signaling pathway, initiates antimicrobial peptide (AMP) production in response to infection by gram-negative bacteria. A membrane-spanning peptidoglycan recognition protein, PGRP-LC, functions as the receptor for the IMD pathway. This receptor is activated via pattern recognition and binding of monomeric peptidoglycan (DAP-type PGN) through the PGRP ectodomain. In this article, we show that the receptor PGRP-LC is down-regulated in response to Salmonella/Escherichia coli infection but is not affected by Staphylococcus infection in vivo, and an ectodomain-deleted PGRP-LC lacking the PGRP domain is an active receptor. We show that the receptor PGRP-LC regulates and integrates two host defense systems: the AMP production and melanization. A working model is proposed in which pathogen invasion and tissue damage may be monitored through the receptor integrity of PGRP-LC after host and pathogen are engaged via pattern recognition. The irreversible cleavage or down-regulation of PGRP-LC may provide an additional cue for the host to distinguish pathogenic microbes from nonpathogenic ones and to subsequently activate multiple host defense systems in Drosophila, thereby effectively combating bacterial infection and initiating tissue repair.
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Affiliation(s)
- Rebecca L Schmidt
- Department of Biochemistry and Molecular Biology, Mayo Clinic College of Medicine, 200 First St. SW, Rochester, MN 55905 USA
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114
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Zipfel C. Pattern-recognition receptors in plant innate immunity. Curr Opin Immunol 2008; 20:10-6. [PMID: 18206360 DOI: 10.1016/j.coi.2007.11.003] [Citation(s) in RCA: 363] [Impact Index Per Article: 22.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2007] [Revised: 11/08/2007] [Accepted: 11/09/2007] [Indexed: 02/02/2023]
Affiliation(s)
- Cyril Zipfel
- The Sainsbury Laboratory, John Innes Centre, Colney Lane, Norwich NR4 7UH, UK.
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115
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Stellato C. Glucocorticoid actions on airway epithelial responses in immunity: functional outcomes and molecular targets. J Allergy Clin Immunol 2008; 120:1247-63; quiz 1264-5. [PMID: 18073120 DOI: 10.1016/j.jaci.2007.10.041] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2007] [Revised: 10/26/2007] [Accepted: 10/29/2007] [Indexed: 12/27/2022]
Abstract
Research on the biology of airway epithelium in the last decades has progressively uncovered the many roles of this cell type during the immune response. Far from the early view of the epithelial layer simply as a passive barrier, the airway epithelium is now considered a central player in mucosal immunity, providing innate mechanisms of first-line host defense as well as facilitating adaptive immune responses. Alterations of the epithelial phenotype are primarily involved in the pathogenesis of allergic airways disease, particularly in severe asthma. Appreciation of the epithelium as target of glucocorticoid therapy has also grown, because of studies defining the pathways and mediators affected by glucocorticoids, and studies illustrating the relevance of the control of the response from epithelium in the overall efficacy of topical and systemic therapy with glucocorticoids. Studies of the mechanism of action of glucocorticoids within the biology of the immune response of the epithelium have uncovered mechanisms of gene regulation involving both transcriptional and posttranscriptional events. The view of epithelium as therapeutic target therefore has plenty of room to evolve, as new knowledge on the role of epithelium in immunity is established and novel pathways mediating glucocorticoid regulation are elucidated.
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Affiliation(s)
- Cristiana Stellato
- Division of Allergy and Clinical Immunology, Johns Hopkins University, Baltimore, MD, USA.
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116
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Mechanisms for Hsp70 secretion: crossing membranes without a leader. Methods 2008; 43:168-75. [PMID: 17920512 DOI: 10.1016/j.ymeth.2007.06.009] [Citation(s) in RCA: 142] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2007] [Accepted: 06/25/2007] [Indexed: 02/02/2023] Open
Abstract
Heat shock protein 70 (Hsp70) is released from cells of many types and plays a significant signaling role, particularly in the inflammatory and immune responses. However, Hsp70 does not contain a consensus secretory signal and thus cannot traverse the plasma membrane by conventional mechanisms. However, Hsp70 can be released from cells by active mechanism that are independent of de novo Hsp70 synthesis or cell death. This pathway is similar to one utilized by the leaderless protein interleukin 1beta. Hsp70 release involves transit through an endolysosomal compartment and is inhibited by lysosomotropic compounds. In addition, the rate of Hsp70 secretion correlates well with the appearance of the lysosomal marker LAMP1 on the cell surface, further suggesting the role for endolysosomes. The entry of Hsp70 into this secretory compartment appears to involve the ABC-family transporter proteins. While the cell signals involved in triggering Hsp70 release through this lysosomal pathway are largely unknown, recent data suggest a regulatory role for extracellular ATP. These mechanisms are also shared by interleukin 1beta secretion. Following release it has been shown that Hsp70 binds to adjacent cells, suggesting that the secreted protein participates in paracrine or autocrine interactions with adjacent cell surfaces. Thus an outline is beginning to of the mechanisms of Hsp70 secretion. Much further study will be required to fully elucidate mechanisms involved in targeting Hsp70 towards the non-canonical secretion pathways and its regulation.
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117
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Molinaro A, Silipo A, Castro CD, Sturiale L, Nigro G, Garozzo D, Bernardini ML, Lanzetta R, Parrilli M. Full structural characterization of Shigella flexneri M90T serotype 5 wild-type R-LPS and its delta galU mutant: glycine residue location in the inner core of the lipopolysaccharide. Glycobiology 2008; 18:260-9. [PMID: 18174310 DOI: 10.1093/glycob/cwm140] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Shigella flexneri is a gram-negative bacterium responsible for serious enteric infections that occur mainly in the terminal ileum and colon. High interest in Shigella, as a human pathogen, is driven by its antibiotic resistance and the necessity to develop a vaccine against its infections. Vaccines of the last generation use carbohydrate moieties of the lipopolysaccharide as probable candidates. For this reason, the primary structure of the core oligosaccharide from the R-LPS produced by S. flexneri M90T serotype 5 using chemical analysis, nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry (MALDI), is herein reported. This is the first time that the core oligosaccharide primary structure by S. flexneri M90T is established in an unambiguous multidisciplinary approach. Chemical and spectroscopical investigation of the de-acetylated LPS showed that the inner core structure is characterized by a L,D-Hep-(1 -->7)-L,D-Hep-(1 -->3)-L,D-Hep-(1 -->5)-[Kdo-(2 -->4)]-Kdo sequence that is the common structural theme identified in Enterobacteriaceae. In particular, in S. flexneri M90T serotype 5 LPS, a glucosamine residue is additionally sitting at O-7 of the last heptose whereas the outer core is characterized by glucose and galactose residues. Also, in order to exactly define the position of glycine that is an integral constituent of the core region of the LPS, we created a S. flexneri M90T delta galU mutant and studied its LOS. In this way it was possible to establish that glycine is sitting at O-6 of the second heptose in the inner core.
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Affiliation(s)
- Antonio Molinaro
- Dipartimento di Chimica Organica e Biochimica, Università degli Studi di Napoli Federico II, Via Cintia 4, I-80126 Napoli, Italy.
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118
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Abstract
The clinical syndrome of sepsis encompasses a highly heterogeneous group of clinical disorders, varying with respect to the site, bacteriology, and even presence of infection and with the clinical syndrome evolving in the host. Clinical trials of strategies to modulate the host response that mediates sepsis were first initiated 25 years ago. A continuing record of disappointment has characterized subsequent work, and only a single new therapy has been licensed for clinical use. Yet, these commercial disappointments obscure a vibrant body of new knowledge that has clarified the biology of the innate immune response whose deranged expression is responsible for sepsis and that has provided important new insights into the failings of the traditional model of clinical research in sepsis. This review highlights advances in basic biology and underlines insights from clinical research that may point to new and more effective ways of translating an understanding of innate immunity into effective treatments for a leading cause of global morbidity and mortality.
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Affiliation(s)
- John C Marshall
- Department of Surgery and Critical Care Medicine, St. Michael's Hospital, University of Toronto, 30 Bond Street, Toronto, Ontario, Canada.
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119
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Carruthers VB, Cotter PA, Kumamoto CA. Microbial pathogenesis: mechanisms of infectious disease. Cell Host Microbe 2007; 2:214-9. [PMID: 18005739 DOI: 10.1016/j.chom.2007.09.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
The FASEB Summer Research Conference on Microbial Pathogenesis: Mechanisms of Infectious Disease was held in Colorado, USA in July 2007. The central theme was the interplay between pathogenic microbes and their mammalian hosts. Here, we review the presented research that highlights this theme, including studies of both short-term and long-term interactions between microbes and their hosts.
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Affiliation(s)
- Vern B Carruthers
- Department of Microbiology and Immunology, University of Michigan, Ann Arbor, MI 48109, USA
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120
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Abstract
Neutrophils constitute the dominant cell in the circulation that mediates the earliest innate immune human responses to infection. The morbidity and mortality from infection rise dramatically in patients with quantitative or qualitative neutrophil defects, providing clinical confirmation of the important role of normal neutrophils for human health. Neutrophil-dependent anti-microbial activity against ingested microbes represents the collaboration of multiple agents, including those prefabricated during granulocyte development in the bone marrow and those generated de novo following neutrophil activation. Furthermore, neutrophils cooperate with extracellular agents as well as other immune cells to optimally kill and degrade invading microbes. This brief review focuses attention on two examples of the integrated nature of neutrophil-mediated anti-microbial action within the phagosome. The importance and complexity of myeloperoxidase-mediated events illustrate a collaboration of anti-microbial responses that are endogenous to the neutrophil, whereas the synergy between the phagocyte NADPH (nicotinamide adenine dinucleotide phosphate) oxidase and plasma-derived group IIA phospholipase A(2) exemplifies the collective effects of the neutrophil with an exogenous factor to achieve degradation of ingested staphylococci.
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Affiliation(s)
- William M Nauseef
- Inflammation Program, Department of Medicine, University of Iowa, Iowa City, IA 52241, USA.
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121
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Hachani A, Biskri L, Rossi G, Marty A, Ménard R, Sansonetti P, Parsot C, Van Nhieu GT, Bernardini ML, Allaoui A. IpgB1 and IpgB2, two homologous effectors secreted via the Mxi-Spa type III secretion apparatus, cooperate to mediate polarized cell invasion and inflammatory potential of Shigella flexenri. Microbes Infect 2007; 10:260-8. [PMID: 18316224 DOI: 10.1016/j.micinf.2007.11.011] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2007] [Revised: 11/25/2007] [Accepted: 11/27/2007] [Indexed: 12/20/2022]
Abstract
Type III secretion systems (T3SS) are present in many pathogenic gram-negative bacteria and mediate the translocation of bacterial effector proteins into host cells. Here, we report the phenotypic characterization of S. flexneri ipgB1 and ipgB2 mutants, in which the genes encoding the IpgB1 and IpgB2 effectors have been inactivated, either independently or simultaneously. Like IpgB1, we found that IpgB2 is secreted by the T3SS and its secretion requires the Spa15 chaperone. Upon infection of semi-confluent HeLa cells, the ipgB2 mutant exhibited the same invasive capacity as the wild-type strain and the ipgB1 mutant was 50% less invasive. Upon infection of polarised Caco2-cells, the ipgB2 mutant did not show a significant defect in invasion and the ipgB1 mutant was slightly more invasive than the wild-type strain. Entry of the ipgB1 ipgB2 mutant in polarized cells was reduced by 70% compared to the wild-type strain. Upon infection of the cornea in Guinea pigs, the ipgB2 mutant exhibited a wild-type phenotype, the ipgB1 mutant was hypervirulent and elicited a more pronounced proinflammatory response, while the ipgB1 ipgB2 mutant was highly attenuated. The attenuated phenotype of the ipgB1 ipgB2 mutant was confirmed using a murine pulmonary model of infection and histopathology and immunochemistry studies.
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Affiliation(s)
- Abderrahman Hachani
- Laboratoire de Bactériologie Moléculaire, Université Libre de Bruxelles (ULB), Faculté de Médecine, Route de Lennik, 808, CP 614 B, 1070 Brussels, Belgium
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122
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Campylobacter jejuni-mediated disease pathogenesis: an update. Trans R Soc Trop Med Hyg 2007; 102:123-9. [PMID: 18023831 DOI: 10.1016/j.trstmh.2007.09.019] [Citation(s) in RCA: 108] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2007] [Revised: 09/20/2007] [Accepted: 09/20/2007] [Indexed: 01/01/2023] Open
Abstract
Infection by Campylobacter jejuni is considered to be the most prevalent cause of bacterial-mediated diarrhoeal disease worldwide. Both in the developing and the developed world, young children remain most susceptible. Although disease is generally mild and self-limiting, severe post-infectious complications such as Gullain-Barré syndrome may occur. Despite the significant health burden caused by the organism, our current understanding of disease pathogenesis remains in its infancy. Elucidation of the genome sequences of many different C. jejuni strains in recent years has started to accelerate research in Campylobacter genetics, pathogenesis and host immunity in response to infection. Campylobacter jejuni is the first prokaryote shown to code for both O- and N-linked glycosylation systems, a feature that is likely to not only modulate bacterial virulence and survival, but also influence host-pathogen interactions and disease outcome. Here recent developments in C. jejuni research, with a particular focus on disease pathogenesis including early host immune responses, are highlighted.
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123
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de Swart RL, van den Hoogen BG, Kuiken T, Herfst S, van Amerongen G, Yüksel S, Sprong L, Osterhaus ADME. Immunization of macaques with formalin-inactivated human metapneumovirus induces hypersensitivity to hMPV infection. Vaccine 2007; 25:8518-28. [PMID: 17996988 DOI: 10.1016/j.vaccine.2007.10.022] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2007] [Revised: 09/27/2007] [Accepted: 10/03/2007] [Indexed: 11/28/2022]
Abstract
Human metapneumovirus (hMPV), a member of the family Paramyxoviridae, is an important cause of acute respiratory tract disease. In the 1960s, vaccination with formalin-inactivated paramyxovirus preparations--respiratory syncytial virus (RSV) and measles virus (MV)--resulted in predisposition for enhanced disease upon natural infection. We have produced a formalin-inactivated hMPV preparation (FI-hMPV), which was used to immunize young cynomolgus macaques. Six days after challenge FI-hMPV-primed monkeys had developed eosinophilic bronchitis and bronchiolitis, indicative of a hypersensitivity response. This study indicates that formalin-inactivated hMPV vaccines have the same propensity to predispose for immune-mediated disease as inactivated RSV and MV vaccines.
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Affiliation(s)
- Rik L de Swart
- Department of Virology, Erasmus MC, P.O. Box 2040, 3000 CA Rotterdam, The Netherlands.
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Folcik VA, An GC, Orosz CG. The Basic Immune Simulator: an agent-based model to study the interactions between innate and adaptive immunity. Theor Biol Med Model 2007; 4:39. [PMID: 17900357 PMCID: PMC2186321 DOI: 10.1186/1742-4682-4-39] [Citation(s) in RCA: 111] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2007] [Accepted: 09/27/2007] [Indexed: 01/10/2023] Open
Abstract
BACKGROUND We introduce the Basic Immune Simulator (BIS), an agent-based model created to study the interactions between the cells of the innate and adaptive immune system. Innate immunity, the initial host response to a pathogen, generally precedes adaptive immunity, which generates immune memory for an antigen. The BIS simulates basic cell types, mediators and antibodies, and consists of three virtual spaces representing parenchymal tissue, secondary lymphoid tissue and the lymphatic/humoral circulation. The BIS includes a Graphical User Interface (GUI) to facilitate its use as an educational and research tool. RESULTS The BIS was used to qualitatively examine the innate and adaptive interactions of the immune response to a viral infection. Calibration was accomplished via a parameter sweep of initial agent population size, and comparison of simulation patterns to those reported in the basic science literature. The BIS demonstrated that the degree of the initial innate response was a crucial determinant for an appropriate adaptive response. Deficiency or excess in innate immunity resulted in excessive proliferation of adaptive immune cells. Deficiency in any of the immune system components increased the probability of failure to clear the simulated viral infection. CONCLUSION The behavior of the BIS matches both normal and pathological behavior patterns in a generic viral infection scenario. Thus, the BIS effectively translates mechanistic cellular and molecular knowledge regarding the innate and adaptive immune response and reproduces the immune system's complex behavioral patterns. The BIS can be used both as an educational tool to demonstrate the emergence of these patterns and as a research tool to systematically identify potential targets for more effective treatment strategies for diseases processes including hypersensitivity reactions (allergies, asthma), autoimmunity and cancer. We believe that the BIS can be a useful addition to the growing suite of in-silico platforms used as an adjunct to traditional research efforts.
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Affiliation(s)
- Virginia A Folcik
- Pulmonary, Allergy, Critical Care and Sleep Medicine Division, Department of Internal Medicine, The Ohio State University College of Medicine, 3102 Cramblett Hall, 456 W.10St., Columbus, Ohio, 43210, USA
| | - Gary C An
- Divison of Trauma/Critical Care, Department of Surgery, Northwestern University Feinberg School of Medicine, 10-105 Galter Pavillion, 201 East Huron, Chicago, IL, 60611, USA
| | - Charles G Orosz
- Department of Surgery/Transplant, The Ohio State University College of Medicine, 350 Means Hall, 1654 Upham Dr., Columbus, Ohio, 43210, USA
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Gibot S, Massin F, Cravoisy A, Barraud D, Nace L, Levy B, Bollaert PE. High-mobility group box 1 protein plasma concentrations during septic shock. Intensive Care Med 2007; 33:1347-53. [PMID: 17525840 DOI: 10.1007/s00134-007-0691-2] [Citation(s) in RCA: 116] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2007] [Accepted: 04/26/2007] [Indexed: 12/20/2022]
Abstract
OBJECTIVE To investigate plasma high-mobility group box 1 protein (HMGB1) concentration and its relationship with organ dysfunction and outcome in septic shock patients. DESIGN AND SETTING Prospective, noninterventional study. Medical adult intensive care unit at a university hospital in France. PATIENTS 42 critically ill patients with septic shock. METHODS Arterial blood was drawn within 12 h of admission for the measurement of plasma HMGB1 concentration by ELISA. Repeated sampling was performed on days 3, 7, and 14. RESULTS Median HMGB1 concentration was 4.4 ng/ml (IQR 1.2-12.5) at admission, with no difference between survivors and nonsurvivors. A positive correlation was observed between HMGB1 and SOFA score and lactate, and procalcitonin concentrations. There was a progressive but statistically nonsignificant decline in HMGB1 concentration among the survivors, while nonsurvivors showed an increase in HMGB1 level between days 1 and 3. SOFA score and lactate and procalcitonin concentrations did not vary significantly between days 1 and 3. When measured on day 3, HMGB1 discriminated survivors from nonsurvivors with 66% sensitivity and 67% specificity, and concentration greater than 4 ng/ml was associated with an odds ratio of death of 5.5 (95% CI 1.3-23.6).
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Affiliation(s)
- Sébastien Gibot
- Hôpital Central, Service de Réanimation Médicale, 29 avenue du Maréchal de Lattre de Tassigny, 54000, Nancy, France.
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de Jonge WJ, Ulloa L. The alpha7 nicotinic acetylcholine receptor as a pharmacological target for inflammation. Br J Pharmacol 2007; 151:915-29. [PMID: 17502850 PMCID: PMC2042938 DOI: 10.1038/sj.bjp.0707264] [Citation(s) in RCA: 467] [Impact Index Per Article: 27.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The physiological regulation of the immune system encompasses comprehensive anti-inflammatory mechanisms that can be harnessed for the treatment of infectious and inflammatory disorders. Recent studies indicate that the vagal nerve, involved in control of heart rate, hormone secretion and gastrointestinal motility, is also an immunomodulator. In experimental models of inflammatory diseases, vagal nerve stimulation attenuates the production of proinflammatory cytokines and inhibits the inflammatory process. Acetylcholine, the principal neurotransmitter of the vagal nerve, controls immune cell functions via the alpha7 nicotinic acetylcholine receptor (alpha7nAChR). From a pharmacological perspective, nicotinic agonists are more efficient than acetylcholine at inhibiting the inflammatory signaling and the production of proinflammatory cytokines. This 'nicotinic anti-inflammatory pathway' may have clinical implications as treatment with nicotinic agonists can modulate the production of proinflammatory cytokines from immune cells. Nicotine has been tested in clinical trials as a treatment for inflammatory diseases such as ulcerative colitis, but the therapeutic potential of this mechanism is limited by the collateral toxicity of nicotine. Here, we review the recent advances that support the design of more specific receptor-selective nicotinic agonists that have anti-inflammatory effects while eluding its collateral toxicity.
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Affiliation(s)
- W J de Jonge
- Department of Gastroenterology, Academic Medical Center, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands.
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Kanzler H, Barrat FJ, Hessel EM, Coffman RL. Therapeutic targeting of innate immunity with Toll-like receptor agonists and antagonists. Nat Med 2007; 13:552-9. [PMID: 17479101 DOI: 10.1038/nm1589] [Citation(s) in RCA: 666] [Impact Index Per Article: 39.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The identification of the antigen recognition receptors for innate immunity, most notably the Toll-like receptors, has sparked great interest in therapeutic manipulation of the innate immune system. Toll-like receptor agonists are being developed for the treatment of cancer, allergies and viral infections, and as adjuvants for potent new vaccines to prevent or treat cancer and infectious diseases. As recognition grows of the role of inappropriate Toll-like receptor stimulation in inflammation and autoimmunity, significant efforts have begun to develop antagonists to Toll-like receptors as well.
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Affiliation(s)
- Holger Kanzler
- Dynavax Technologies, 2929 Seventh Street, Suite 100, Berkeley, California 94710, USA
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Kelly D, King T, Aminov R. Importance of microbial colonization of the gut in early life to the development of immunity. Mutat Res 2007; 622:58-69. [PMID: 17612575 DOI: 10.1016/j.mrfmmm.2007.03.011] [Citation(s) in RCA: 159] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2007] [Revised: 03/27/2007] [Accepted: 03/28/2007] [Indexed: 12/16/2022]
Abstract
The mammalian gastrointestinal tract harbors a complex microbiota consisting of between 500 and 1000 distinct microbial species. Comparative studies based on the germ-free gut have provided clear evidence that the gut microbiota is instrumental in promoting the development of both the gut and systemic immune systems. Early microbial exposure of the gut is thought to dramatically reduce the incidence of inflammatory, autoimmune and atopic diseases further fuelling the scientific viewpoint, that microbial colonization plays an important role in regulating and fine-tuning the immune system throughout life. Recent molecular diversity studies have provided additional evidence that the human gut microbiota is compositionally altered in individuals suffering from inflammatory bowel disorders, suggesting that specific bacterial species are important to maintaining immunological balance and health. New and exciting insights into how gut bacteria modulate the mammalian immune system are emerging. However, much remains to be elucidated about how commensal bacteria influence the function of cells of both the innate and adaptive immune systems in health and disease.
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