501
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Kaser A, Blumberg RS. Autophagy, microbial sensing, endoplasmic reticulum stress, and epithelial function in inflammatory bowel disease. Gastroenterology 2011; 140:1738-47. [PMID: 21530740 PMCID: PMC4592160 DOI: 10.1053/j.gastro.2011.02.048] [Citation(s) in RCA: 116] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/12/2010] [Revised: 02/09/2011] [Accepted: 02/10/2011] [Indexed: 12/13/2022]
Abstract
Increasing evidence has emerged that supports an important intersection between 3 fundamental cell biologic pathways in the pathogenesis of inflammatory bowel disease. These include the intersection between autophagy, as revealed by the original identification of ATG16L1 and IRGM as major genetic risk factors for Crohn's disease, and intracellular bacterial sensing, as shown by the importance of NOD2 in autophagy induction upon bacterial entry into the cell. A pathway closely linked to autophagy and innate immunity is the unfolded protein response, initiated by endoplasmic reticulum stress due to the accumulation of misfolded proteins, which is genetically related to ulcerative colitis and Crohn's disease (XBP1 and ORMDL3). Hypomorphic ATG16L1, NOD2, and X box binding protein-1 possess the common attribute of profoundly affecting Paneth cells, specialized epithelial cells at the bottom of intestinal crypts involved in antimicrobial function. Together with their functional juxtaposition in the environmentally exposed intestinal epithelial cell, their remarkable functional convergence on Paneth cells and their behavior in response to environmental factors, including microbes, these 3 pathways are of increasing importance to understanding the pathogenesis of inflammatory bowel disease. Moreover, in conjunction with studies that model deficient nuclear factor-κB function, these studies suggest a central role for altered intestinal epithelial cell function as one of the earliest events in the development of inflammatory bowel disease.
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Affiliation(s)
- Arthur Kaser
- Division of Gastroenterology and Hepatology, Department of Medicine, University of Cambridge, Addenbrooke’s Hospital, Cambridge, United Kingdom,Department of Medicine II, Innsbruck Medical University, Innsbruck, Austria
| | - Richard S. Blumberg
- Division of Gastroenterology, Hepatology and Endoscopy, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts
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502
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Abstract
Interferon regulatory factor 7 (IRF7) was originally identified in the context of Epstein-Barr virus (EBV) infection, and has since emerged as the crucial regulator of type I interferons (IFNs) against pathogenic infections, which activate IRF7 by triggering signaling cascades from pathogen recognition receptors (PRRs) that recognize pathogenic nucleic acids. Moreover, IRF7 is a multifunctional transcription factor, underscored by the fact that it is associated with EBV latency, in which IRF7 is induced as well as activated by the EBV principal oncoprotein latent membrane protein-1 (LMP1). Aberrant production of type I IFNs is associated with many types of diseases such as cancers and autoimmune disorders. Thus, tight regulation of IRF7 expression and activity is imperative in dictating appropriate type I IFN production for normal IFN-mediated physiological functions. Posttranslational modifications have important roles in regulation of IRF7 activity, exemplified by phosphorylation, which is indicative of its activation. Furthermore, mounting evidence has shed light on the importance of regulatory ubiquitination in activation of IRF7. Albeit these exciting findings have been made in the past decade since its discovery, many questions related to IRF7 remain to be addressed.
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503
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Dectin-1 and NOD2 mediate cathepsin activation in zymosan-induced arthritis in mice. Inflamm Res 2011; 60:705-14. [PMID: 21424514 DOI: 10.1007/s00011-011-0324-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2011] [Revised: 02/23/2011] [Accepted: 02/28/2011] [Indexed: 01/29/2023] Open
Abstract
OBJECTIVE Activation of pattern recognition receptors (PRR) may contribute to arthritis. Here, we elucidated the role of NOD2, a genetic cause of inflammatory arthritis, and several other PRR in a murine model of inflammatory arthritis. METHODS The roles of CR3, TLR2, MyD88, NOD1, NOD2, Dectin-1 and Dectin-2 were tested in vivo in arthritis elicited by intra-articular injections of zymosan, the fungal cell wall components curdlan, laminarin and mannan, and the bacterial cell wall peptidoglycan. RESULTS Dectin-1, and to a lesser extent Dectin-2, contributed to arthritis. TLR2, MyD88 and CR3 played non-essential roles. Observations based on injection of curdlan, laminarin or mannan supported the dominant role of the Dectin-1 pathway in the joint. We demonstrated differential roles for NOD1 and NOD2 and identified NOD2 as a novel and essential mediator of zymosan-induced arthritis. CONCLUSIONS Together, Dectin-1 and NOD2 are critical, sentinel receptors in the arthritogenic effects of zymosan. Our data identify a novel role for NOD2 during inflammatory responses within joints.
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504
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Sumpter R, Levine B. Selective autophagy and viruses. Autophagy 2011; 7:260-5. [PMID: 21150267 PMCID: PMC3060412 DOI: 10.4161/auto.7.3.14281] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2010] [Revised: 11/23/2010] [Accepted: 11/24/2010] [Indexed: 01/20/2023] Open
Abstract
In recent years, the process of selective autophagy has received much attention with respect to the clearance of protein aggregates, damaged mitochondria and bacteria. However, until recently, there have been virtually no studies on the selective autophagy of viruses, although they are perhaps one of the most ubiquitous unwanted constituents in human cells. Recently, we have shown that the ability of neuronal Atg5 to protect against lethal Sindbis virus central nervous system (CNS) infection in mice is associated with impaired viral capsid clearance, increased p62 accumulation and increased neuronal cell death. In vitro, we showed that p62 interacts with the Sindbis capsid protein and targets it for degradation in autophagosomes. Herein, we review these findings and broadly speculate about potential roles of selective viral autophagy in the regulation of host immunity and viral pathogenesis.
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Affiliation(s)
- Rhea Sumpter
- Department of Internal Medicine University of Texas Southwestern Medical Center; Dallas, TX USA
| | - Beth Levine
- Department of Internal Medicine University of Texas Southwestern Medical Center; Dallas, TX USA
- Department of Microbiology University of Texas Southwestern Medical Center; Dallas, TX USA
- Howard Hughes Medical Institute; University of Texas Southwestern Medical Center; Dallas, TX USA
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505
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506
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Billmann-Born S, Till A, Arlt A, Lipinski S, Sina C, Latiano A, Annese V, Häsler R, Kerick M, Manke T, Seegert D, Hanidu A, Schäfer H, van Heel D, Li J, Schreiber S, Rosenstiel P. Genome-wide expression profiling identifies an impairment of negative feedback signals in the Crohn's disease-associated NOD2 variant L1007fsinsC. THE JOURNAL OF IMMUNOLOGY 2011; 186:4027-38. [PMID: 21335489 DOI: 10.4049/jimmunol.1000085] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
NOD2 is an intracellular receptor for the bacterial cell wall component muramyl dipeptide (MDP), and variants of NOD2 are associated with chronic inflammatory diseases of barrier organs (e.g., Crohn's disease, asthma, and atopic eczema). It is known that activation of NOD2 induces a variety of inflammatory and antibacterial factors. The exact transcriptomal signatures that define the cellular programs downstream of NOD2 activation and the influence of the Crohn-associated variant L1007fsinsC are yet to be defined. To describe the MDP-induced activation program, we analyzed the transcriptomal reactions of isogenic HEK293 cells expressing NOD2(wt) or NOD2(L1007fsinsC) to stimulation with MDP. Importantly, a clear loss of function could be observed in the cells carrying the Crohn-associated variant L1007fsinsC, whereas the NOD2(wt) cells showed differential regulation of growth factors, chemokines, and several antagonists of NF-κB (e.g., TNFAIP3 [A20] and IER3). This genotype-dependent regulation pattern was confirmed in primary human myelomonocytic cells. The influence of TNFAIP3 and IER3 in the context of NOD2 signaling was characterized, and we could validate the predicted role as inhibitors of NOD2-induced NF-κB activation. We show that IER3 impairs the protective effect of NOD2(wt) against bacterial cytoinvasion. These results further our understanding of NOD2 as a first-line defense molecule and emphasize the importance of simultaneous upregulation of counterregulatory anti-inflammatory factors as an integral part of the NOD2-induced cellular program. Lack of these regulatory events due to the L1007fsinsC variant may pivotally contribute to the induction and perpetuation of chronic inflammation.
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Affiliation(s)
- Susanne Billmann-Born
- Institute of Clinical Molecular Biology, Christian-Albrechts-University, 24105 Kiel, Germany
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507
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Wang G, Chen G, Zheng D, Cheng G, Tang H. PLP2 of mouse hepatitis virus A59 (MHV-A59) targets TBK1 to negatively regulate cellular type I interferon signaling pathway. PLoS One 2011; 6:e17192. [PMID: 21364999 PMCID: PMC3041802 DOI: 10.1371/journal.pone.0017192] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2010] [Accepted: 01/24/2011] [Indexed: 12/20/2022] Open
Abstract
Background Coronaviruses such as severe acute respiratory syndrome (SARS) coronavirus (SCoV) and mouse hepatitis virus A59 (MHV-A59) have evolved strategies to disable the innate immune system for productive replication and spread of infection. We have previously shown that papain-like protease domain 2 (PLP2), a catalytic domain of the nonstructural protein 3 (nsp3) of MHV-A59, encodes a deubiquitinase (DUB) and inactivates IFN regulatory factor 3 (IRF3) thereby the type I interferon (IFN) response. Principal Findings Here we provide further evidence that PLP2 may also target TANK-binding kinase-1 (TBK1), the upstream kinase of IRF3 in the IFN signaling pathway. Overexpression experiments showed that PLP2 deubiquitinated TBK1 and reduced its kinase activity, hence inhibited IFN-β reporter activity. Albeit promiscuous in deubiquitinating cellular proteins, PLP2 inactivated TBK1 and IFN-β response in TNF receptor associated factor 3 (TRAF3) deficient cells, suggesting that targeting TBK1 would be sufficient for PLP2 to inhibit IRF3 activation. This notion was further supported by in vitro kinase assays, in which prior treatment of TBK1 with PLP2 inhibited its kinase activity to phosphorylate IRF3. Intriguing enough, results of PLP2 overexpression system and MHV-A59 infection system proved that PLP2 formed an inactive complex with TBK1 and IRF3 in the cytoplasm and the presence of PLP2 stabilized the hypo-phosphorylated IRF3-TBK1 complex in a dose-dependent manner. Conclusions These results suggest that PLP2 not only inactivates TBK1, but also prevents IRF3 nuclear translocation hence inhibits IFN transcription activation. Identification of the conserved DUB activity of PLP2 in suppression of IFN signaling would provide a useful clue to the development of therapeutics against coronaviruses infection.
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Affiliation(s)
- Gang Wang
- Key Laboratory of Infection and Immunity, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
- Research Network of Immunity and Health, Beijing Institutes of Life Science, Chinese Academy of Sciences, Beijing, China
- Graduate University, Chinese Academy of Sciences, Beijing, China
| | - Gang Chen
- Key Laboratory of Infection and Immunity, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Dahai Zheng
- Key Laboratory of Infection and Immunity, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Genhong Cheng
- Department of Microbiology, Immunology and Molecular Genetics, University of California Los Angeles, Los Angeles, California, United States of America
| | - Hong Tang
- Key Laboratory of Infection and Immunity, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
- Research Network of Immunity and Health, Beijing Institutes of Life Science, Chinese Academy of Sciences, Beijing, China
- * E-mail:
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508
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Zurek B, Proell M, Wagner RN, Schwarzenbacher R, Kufer TA. Mutational analysis of human NOD1 and NOD2 NACHT domains reveals different modes of activation. Innate Immun 2011; 18:100-11. [PMID: 21310790 DOI: 10.1177/1753425910394002] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Nucleotide-binding oligomerization domain-containing protein (NOD)1 and NOD2 are intracellular pattern recognition receptors (PRRs) of the nucleotide-binding domain and leucine-rich repeat containing (NLR) gene family involved in innate immune responses. Their centrally located NACHT domain displays ATPase activity and is necessary for activation and oligomerization leading to inflammatory signaling responses. Mutations affecting key residues of the ATPase domain of NOD2 are linked to severe auto-inflammatory diseases, such as Blau syndrome and early-onset sarcoidosis. By mutational dissection of the ATPase domain function, we show that the NLR-specific extended Walker B box (DGhDE) can functionally replace the canonical Walker B sequence (DDhWD) found in other ATPases. A requirement for an intact Walker A box and the magnesium-co-ordinating aspartate of the classical Walker B box suggest that an initial ATP hydrolysis step is necessary for activation of both NOD1 and NOD2. In contrast, a Blau-syndrome associated mutation located in the extended Walker B box of NOD2 that results in higher autoactivation and ligand-induced signaling does not affect NOD1 function. Moreover, mutation of a conserved histidine in the NACHT domain also has contrasting effects on NOD1 and NOD2 mediated NF-κB activation. We conclude that these two NLRs employ different modes of activation and propose distinct models for activation of NOD1 and NOD2.
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Affiliation(s)
- Birte Zurek
- Institute for Medical Microbiology, Immunology and Hygiene, University of Cologne, Cologne, Germany
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509
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The IRF-3/Bax-mediated apoptotic pathway, activated by viral cytoplasmic RNA and DNA, inhibits virus replication. J Virol 2011; 85:3708-16. [PMID: 21307205 DOI: 10.1128/jvi.02133-10] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Induction of apoptosis in cells infected by Sendai virus (SeV), which triggers the cytosolic RIG-I pathway, requires the presence of interferon regulatory factor 3 (IRF-3). Independent of IRF-3's transcriptional role, a novel IRF-3 activation pathway causes its interaction with the proapoptotic protein Bax and its mitochondrial translocation to induce apoptosis. Here we report that two other RNA viruses, vesicular stomatitis virus (VSV) and encephalomyocarditis virus (EMCV), may also activate the same pathway. Moreover, cytosolic DNA, produced by adenovirus or introduced by transfection, activated the pathway in an RNA polymerase III-dependent fashion. To evaluate the contribution of this newly discovered apoptotic pathway to the host's overall antiviral response, we measured the efficiencies of replication of various viruses in vitro and viral pathogenesis in vivo, using cells and mice that are selectively deficient in components required for the apoptotic pathway of IRF-3. Our results clearly demonstrate that the IRF-3/Bax-mediated apoptotic signaling branch contributes significantly to the host's protection from viral infection and consequent pathogenesis.
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510
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Packwood K, Drewe E, Staples E, Webster D, Witte T, Litzman J, Egner W, Sargur R, Sewell W, Lopez-Granados E, Seneviratne SL, Powell RJ, Ferry BL, Chapel HM. NOD2 polymorphisms in clinical phenotypes of common variable immunodeficiency disorders. Clin Exp Immunol 2011; 161:536-41. [PMID: 20646002 DOI: 10.1111/j.1365-2249.2010.04216.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Common variable immunodeficiency disorders (CVIDs) are a heterogeneous group of diseases characterized by hypogammaglobulinaemia and consequent susceptibility to infection. CVID patients commonly develop a variety of additional manifestations for which the causative factors are not fully understood. Two such manifestations are granulomatous disease and enteropathy. Because the ability to predict complications would aid clinical management, we continue to search for possible disease modifier genes. NOD2 acts a microbial sensor and is involved in proinflammatory signalling. Particular mutations of the NOD2 gene are associated with Crohn's disease including gly908arg, leu1007finsc and arg702trp polymorphisms. We hypothesized that NOD2 polymorphisms may be a disease modifier gene towards an enteropathic or granulomatous phenotype within CVIDs. Sequence-specific primers returned genotypes for 285 CVID patients from centres across the United Kingdom and Europe. We present the frequencies of the different phenotypes of patients within our international cohort. Arg702trp polymorphisms were significantly less frequent than wild-type (WT) (P = 0·038) among international CVID patients with splenomegaly. Gly908arg polymorphisms were more prevalent than WT in UK patients with autoimmune disorders (P = 0·049) or enteropathy (P = 0·049). NOD2 polymorphisms were not more prevalent than WT in CVID patients with clinical phenotypes of granulomata. UK allele frequencies of 0·014, 0·056 and 0·026 were found for gly908arg, arg702trp and leu1007finsc NOD2 polymorphisms, respectively. These do not differ significantly from UK immunocompetent controls confirming, as expected, that in addition these NOD2 polymorphisms do not confer susceptibility to CVIDs per se.
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Affiliation(s)
- K Packwood
- Department of Immunology, Oxford Radcliffe Hospitals, Oxford, UK.
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511
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Affiliation(s)
- Paul Henderson
- Address for correspondence: Dr P Henderson, Department of Child Life and Health, University of Edinburgh, 20 Sylvan Place, Edinburgh EH9 1UW.
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512
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Echchgadda I, Chang TH, Sabbah A, Bakri I, Ikeno Y, Hubbard GB, Chatterjee B, Bose S. Oncolytic targeting of androgen-sensitive prostate tumor by the respiratory syncytial virus (RSV): consequences of deficient interferon-dependent antiviral defense. BMC Cancer 2011; 11:43. [PMID: 21276246 PMCID: PMC3038980 DOI: 10.1186/1471-2407-11-43] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2010] [Accepted: 01/28/2011] [Indexed: 11/12/2022] Open
Abstract
Background Oncolytic virotherapy for cancer treatment utilizes viruses for selective infection and death of cancer cells without any adverse effect on normal cells. We previously reported that the human respiratory syncytial virus (RSV) is a novel oncolytic virus against androgen-independent PC-3 human prostate cancer cells. The present study extends the result to androgen-dependent prostate cancer, and explores the underlying mechanism that triggers RSV-induced oncolysis of prostate cancer cells. Methods The oncolytic effect of RSV on androgen-sensitive LNCaP human prostate cancer cells and on androgen-independent RM1 murine prostate cancer cells was studied in vitro in culture and in vivo in a xenograft or allograft tumor model. In vitro, cell viability, infectivity and apoptosis were monitored by MTT assay, viral plaque assay and annexin V staining, respectively. In vivo studies involved virus administration to prostate tumors grown in immune compromised nude mice and in syngeneic immune competent C57BL/6J mice. Anti-tumorogenic oncolytic activity was monitored by measuring tumor volume, imaging bioluminescent tumors in live animals and performing histopathological analysis and TUNEL assay with tumors Results We show that RSV imposes a potent oncolytic effect on LNCaP prostate cancer cells. RSV infectivity was markedly higher in LNCaP cells compared to the non-tumorigenic RWPE-1 human prostate cells. The enhanced viral burden led to LNCaP cell apoptosis and growth inhibition of LNCaP xenograft tumors in nude mice. A functional host immune response did not interfere with RSV-induced oncolysis, since growth of xenograft tumors in syngeneic C57BL/6J mice from murine RM1 cells was inhibited upon RSV administration. LNCaP cells failed to activate the type-I interferon (IFNα/β)-induced transcription factor STAT-1, which is required for antiviral gene expression, although these cells could produce IFN in response to RSV infection. The essential role of IFN in restricting infection was further borne out by our finding that neutralizing IFN activity resulted in enhanced RSV infection in non-tumorigenic RWPE-1 prostate cells. Conclusions We demonstrated that RSV is potentially a useful therapeutic tool in the treatment of androgen-sensitive and androgen-independent prostate cancer. Moreover, impaired IFN-mediated antiviral response is the likely cause of higher viral burden and resulting oncolysis of androgen-sensitive prostate cancer cells.
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Affiliation(s)
- Ibtissam Echchgadda
- Department of Microbiology and Immunology, The University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, MC-7758, San Antonio, TX 78229, USA
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513
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Shaw MH, Kamada N, Warner N, Kim YG, Nuñez G. The ever-expanding function of NOD2: autophagy, viral recognition, and T cell activation. Trends Immunol 2011; 32:73-9. [PMID: 21251876 DOI: 10.1016/j.it.2010.12.007] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2010] [Revised: 12/20/2010] [Accepted: 12/21/2010] [Indexed: 02/07/2023]
Abstract
The identification of several families of innate pattern recognition receptors has greatly enhanced our understanding of the host innate immune response against a variety of pathogens. One such family of innate receptors is the nucleotide-binding domain and leucine rich repeat containing receptors (NLRs). NOD2 has been characterized as a cytosolic sensor of bacteria peptidoglycan (PGN). For almost 10 years, NOD2 was assigned with the function of mediating the RICK- and nuclear factor-κB induced proinflammatory response triggered by PGN. Recent studies have extended the biological activity of NOD2 to include the induction of autophagy and antiviral responses, as well as mediating direct T cell activation. Here, we highlight and discuss these new findings in the context of immune activation and pathogen detection.
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Affiliation(s)
- Michael H Shaw
- Department of Pathology and Comprehensive Cancer Center, University of Michigan Medical School, Ann Arbor, MI 48109, USA
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514
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Fitch PM, Henderson P, Schwarze J. Respiratory and gastrointestinal epithelial modulation of the immune response during viral infection. Innate Immun 2011; 18:179-89. [PMID: 21239454 DOI: 10.1177/1753425910391826] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Respiratory and enteric viral infections cause significant morbidity and mortality world-wide and represent a major socio-economic burden. Many of these viruses have received unprecedented public and media interest in recent years. A popular public misconception is that viruses are a threat to which the human body has only limited defences. However, the majority of primary and secondary exposures to virus are asymptomatic or induce only minor symptoms. The mucosal epithelial surfaces are the main portal of entry for viral pathogens and are centrally involved in the initiation, maintenance and polarisation of the innate and adaptive immune response to infection. This review describes the defences employed by the epithelium of the respiratory and gastrointestinal tracts during viral infections with focus on epithelial modulation of the immune response at the innate/adaptive interface.
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Affiliation(s)
- Paul M Fitch
- Centre for Inflammation Research, Queen’s Medical Research Institute, University of Edinburgh, UK
| | - Paul Henderson
- Centre for Inflammation Research, Queen’s Medical Research Institute, University of Edinburgh, UK
- Department of Child Life and Health, University of Edinburgh, UK
| | - Jürgen Schwarze
- Centre for Inflammation Research, Queen’s Medical Research Institute, University of Edinburgh, UK
- Department of Child Life and Health, University of Edinburgh, UK
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515
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Barbalat R, Ewald SE, Mouchess ML, Barton GM. Nucleic acid recognition by the innate immune system. Annu Rev Immunol 2011; 29:185-214. [PMID: 21219183 DOI: 10.1146/annurev-immunol-031210-101340] [Citation(s) in RCA: 446] [Impact Index Per Article: 34.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Receptors of the innate immune system recognize conserved microbial features and provide key signals that initiate immune responses. Multiple transmembrane and cytosolic receptors have evolved to recognize RNA and DNA, including members of the Toll-like receptor and RIG-I-like receptor families and several DNA sensors. This strategy enables recognition of a broad range of pathogens; however, in some cases, this benefit is weighed against the cost of potential self recognition. Recognition of self nucleic acids by the innate immune system contributes to the pathology associated with several autoimmune or autoinflammatory diseases. In this review, we highlight our current understanding of nucleic acid sensing by innate immune receptors and discuss the regulatory mechanisms that normally prevent inappropriate responses to self.
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Affiliation(s)
- Roman Barbalat
- Division of Immunology & Pathogenesis, Department of Molecular and Cell Biology, University of California, Berkeley, 94720-3200, USA
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516
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Abstract
The mammalian immune system comprises an adaptive and an innate component. The innate immune system employs a limited number of germ-line-encoded pattern-recognition receptors (PRRs) that recognize invariant pathogen-associated molecular patterns (PAMPs). In contrast, the adaptive immune system depends on the generation of a diverse repertoire of antigen receptors on T and B lymphocytes and subsequent activation and clonal expansion of cells carrying the appropriate antigen-specific receptors. Induction of adaptive immunity not only depends on direct antigen recognition by the antigen receptors but also relies on essential signals that are delivered by the innate immune system. In recent years, we have witnessed the discovery of a still expanding array of different PRR systems that govern the generation of adaptive immunity. Here, we review our current understanding of innate control of adaptive immunity. In particular, we discuss how PRRs initiate adaptive immune responses in general, discuss specific mechanisms that shape the ensuing T and B cell responses, and highlight open questions that are still awaiting answers.
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Affiliation(s)
- Dominik Schenten
- Howard Hughes Medical Institute, Department of Immunobiology, School of Medicine, Yale University, New Haven, Connecticut, USA
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517
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Henderson P, van Limbergen JE, Wilson DC, Satsangi J, Russell RK. Genetics of childhood-onset inflammatory bowel disease. Inflamm Bowel Dis 2011; 17:346-61. [PMID: 20839313 DOI: 10.1002/ibd.21283] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Nearly a third of inflammatory bowel disease (IBD) patients present in childhood or adolescence, with epidemiological and natural history studies clearly demonstrating a rising incidence in this population. Although early-onset disease has a distinct phenotype, such as more extensive disease at onset and rapid progression, two recent genome-wide association studies (GWAS) carried out exclusively in this age group have demonstrated marked genetic similarities to adult disease. Although these parallels exist, this review will focus on the novel regions associated with early-onset IBD susceptibility identified by these early-onset GWAS. These new loci reaffirm the dysregulated pathways previously implicated in adult IBD pathogenesis and provide further insight into the pathophysiology of intestinal inflammation. The newly identified loci and expression data suggest mutations in genes encoding IL-27, which is involved in Th17 effector cell physiology; MTMR3, which we demonstrate is an essential component of autophagy; and CAPN10, which is necessary in regulating endoplasmic reticulum stress. In addition, the roles of PSMG1, TNFRSF6B, ZMIZ1 and SMAD3 are also discussed in relation to abnormal protein degradation and the secondary immune response. It is clear that with increasing technology our understanding of IBD pathogenesis is deepening at the genomic level and that the use of early patient selection coupled with ongoing work on therapeutic targets will lead to improved disease-modifying treatments in the near future.
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Affiliation(s)
- Paul Henderson
- Department of Paediatric Gastroenterology, Hepatology and Nutrition, Royal Hospital for Sick Children, Edinburgh, UK.
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518
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Abstract
Inflammasome activation leads to caspase-1 activation, which causes the maturation and secretion of pro-IL-1β and pro-IL-18 among other substrates. A subgroup of the NLR (nucleotide-binding domain, leucine-rich repeat containing) proteins are key mediators of the inflammasome. Studies of gene-deficient mice and cells have implicated NLR inflammasomes in a host of responses to a wide range of microbial pathogens, inflammatory diseases, cancer, and metabolic and autoimmune disorders. Determining exactly how the inflammasome is activated in these diseases and disease models remains a challenge. This review presents and integrates recent progress in the field.
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Affiliation(s)
- Beckley K Davis
- Department of Microbiology and Immunology, Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, 27599, USA.
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519
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Abstract
Since the discovery of the protein "interferon" over 50 years ago, IFNβ, an antiviral cytokine, has been well studied. In particular, the pathways inducing this cytokine during viral infection have been characterized, leading to the discovery of a multitude of pattern recognition receptors. IFNβ is also induced during bacterial infection, following recognition of bacterial ligands by the host viral and DNA sensors. However, the function of IFNβ during bacterial infection is variable and sometimes detrimental to the host. This review discusses the currently identified receptors and pathways engaged in IFNβ induction during infection, with emphasis on the role of IFNβ during bacterial infection.
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Affiliation(s)
- Uma Nagarajan
- Division of Pediatric Infectious Diseases, University of Arkansas for Medical Sciences, Arkansas Children's Hospital Research Institute, Little Rock, AR 72202, USA.
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520
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Chakrabarti A, Jha BK, Silverman RH. New insights into the role of RNase L in innate immunity. J Interferon Cytokine Res 2010; 31:49-57. [PMID: 21190483 DOI: 10.1089/jir.2010.0120] [Citation(s) in RCA: 229] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The interferon (IFN)-inducible 2'-5'-oligoadenylate synthetase (OAS)/RNase L pathway blocks infections by some types of viruses through cleavage of viral and cellular single-stranded RNA. Viruses induce type I IFNs that initiate signaling to the OAS genes. OAS proteins are pathogen recognition receptors for the viral pathogen-associated molecular pattern, double-stranded RNA. Double-stranded RNA activates OAS to produce p(x)5'A(2'p5'A)(n); x = 1-3; n > 2 (2-5A) from ATP. Upon binding 2-5A, RNase L is converted from an inactive monomer to a potently active dimeric endoribonuclease for single-stranded RNA. RNase L contains, from N- to C-terminus, a series of 9 ankyrin repeats, a linker, several protein kinase-like motifs, and a ribonuclease domain homologous to Ire1 (involved in the unfolded protein response). In the past few years, it has become increasingly apparent that RNase L and OAS contribute to innate immunity in many ways. For example, small RNA cleavage products produced by RNase L during viral infections can signal to the retinoic acid-inducible-I like receptors to amplify and perpetuate signaling to the IFN-β gene. In addition, RNase L is now implicated in protecting the central nervous system against viral-induced demyelination. A role in tumor suppression was inferred by mapping of the RNase L gene to the hereditary prostate cancer 1 (HPC1) gene, which in turn led to discovery of the xenotropic murine leukemia-related virus. A broader role in innate immunity is suggested by involvement of RNase L in cytokine induction and endosomal pathways that suppress bacterial infections. These newly described findings about RNase L could eventually provide the basis for developing broad-spectrum antimicrobial drugs.
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Affiliation(s)
- Arindam Chakrabarti
- Department of Cancer Biology, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio 44195, USA
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521
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What is new with Nods? Curr Opin Immunol 2010; 23:29-34. [PMID: 21190821 DOI: 10.1016/j.coi.2010.12.003] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2010] [Revised: 12/02/2010] [Accepted: 12/06/2010] [Indexed: 01/01/2023]
Abstract
Over the last few years, much research has focused on determining the function of members of the cytosolic Nod-like receptor (NLR) family in terms of their triggers and the signaling pathways that they control. Members of this family include the NLRP proteins, which play a role in sensing both microbial and danger signals and triggering the caspase-1 dependent inflammasome, and the Nod subfamily characterized by proteins with a caspase-activating and recruitment domain (CARD) or a so-called 'X' domain. Nod1, Nod2, NLRX1 and NLRC5 are all members of this subfamily and in this review, we will focus on recent work that has shown the importance of these molecules in both pathogen sensing and regulation of innate and adaptive immunity.
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522
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Briggs CM, Holder RC, Reid SD, Parks GD. Activation of human macrophages by bacterial components relieves the restriction on replication of an interferon-inducing parainfluenza virus 5 (PIV5) P/V mutant. Microbes Infect 2010; 13:359-68. [PMID: 21185944 DOI: 10.1016/j.micinf.2010.12.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2010] [Revised: 12/04/2010] [Accepted: 12/15/2010] [Indexed: 12/26/2022]
Abstract
Macrophages regulate immune responses during many viral infections, and can be a major determinant of pathogenesis, virus replication and immune response to infection. Here, we have addressed the question of the outcome of infection of primary human macrophages with parainfluenza virus 5 (PIV5) and a PIV5 mutant (P/V-CPI-) that is unable to counteract interferon (IFN) responses. In cultures of naïve monocyte-derived macrophages (MDMs), WT PIV5 established a highly productive infection, whereas the P/V-CPI- mutant was restricted for replication in MDMs by IFN-beta. Restricted replication in vitro was relieved in MDM that had been activated by prior exposure to heat killed Gram positive bacteria, including Listeria monocytogenes, Streptococcus pyogenes, and Bacillus anthracis. Enhanced replication of the P/V mutant in MDM previously activated by bacterial components correlated with a reduced ability to produce IFN-beta in response to virus infection, whereas IFN signaling was intact. Activated MDM were found to upregulate the synthesis of IRAK-M, which has been previously shown to negatively regulate factors involved in TLR signaling and IFN-beta production. We discuss these results in terms of the implications for mixed bacteria-virus infections and for the use of live RNA virus vectors that have been engineered to be attenuated for IFN sensitivity.
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Affiliation(s)
- Caitlin M Briggs
- Department of Microbiology and Immunology, Wake Forest University, School of Medicine, Medical Center Blvd., Winston-Salem, NC 27157-1064, United States
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523
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Cheng G, Wang LCS, Fridlender ZG, Cheng GS, Chen B, Mangalmurti NS, Saloura V, Yu Z, Kapoor V, Mozdzanowska K, Moon E, Sun J, Kreindler JL, Cohen NA, Caton AJ, Erikson J, Albelda SM. Pharmacologic activation of the innate immune system to prevent respiratory viral infections. Am J Respir Cell Mol Biol 2010; 45:480-8. [PMID: 21148741 DOI: 10.1165/rcmb.2010-0288oc] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Drugs that can rapidly inhibit respiratory infection from influenza or other respiratory pathogens are needed. One approach is to engage primary innate immune defenses against viral infection, such as activating the IFN pathway. In this study, we report that a small, cell-permeable compound called 5,6-di-methylxanthenone-4-acetic acid (DMXAA) can induce protection against vesicular stomatitis virus in vitro and H1N1 influenza A virus in vitro and in vivo through innate immune activation. Using the mouse C10 bronchial epithelial cell line and primary cultures of nasal epithelial cells, we demonstrate DMXAA activates the IFN regulatory factor-3 pathway leading to production of IFN-β and subsequent high-level induction of IFN-β-dependent proteins, such as myxovirus resistance 1 (Mx1) and 2',5'-oligoadenylate synthetase 1 (OAS1). Mice treated with DMXAA intranasally elevate mRNA/protein expression of Mx1 and OAS1 in the nasal mucosa, trachea, and lung. When challenged intranasally with a lethal dose of H1N1 influenza A virus, DMXAA reduced viral titers in the lungs and protected 80% of mice from death, even when given at 24 hours before infection. These data show that agents, like DMXAA, that can directly activate innate immune pathways, such as the IFN regulatory factor-3/IFN-β system, in respiratory epithelial cells can be used to protect from influenza pneumonia and potentially in other respiratory viral infections. Development of this approach in humans could be valuable for protecting health care professionals and "first responders" in the early stages of viral pandemics or bioterror attacks.
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Affiliation(s)
- Guanjun Cheng
- Thoracic Oncology Research Laboratory, 1015F ARC, University of Pennsylvania, 3615 Civic Center Boulevard, Philadelphia, PA 19104-4318, USA
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524
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Jiang J, Tang H. Mechanism of inhibiting type I interferon induction by hepatitis B virus X protein. Protein Cell 2010; 1:1106-17. [PMID: 21213104 PMCID: PMC4875076 DOI: 10.1007/s13238-010-0141-8] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2010] [Accepted: 12/02/2010] [Indexed: 12/21/2022] Open
Abstract
Hepatitis B virus (HBV) is regarded as a stealth virus, invading and replicating efficiently in human liver undetected by host innate antiviral immunity. Here, we show that type I interferon (IFN) induction but not its downstream signaling is blocked by HBV replication in HepG2.2.15 cells. This effect may be partially due to HBV X protein (HBx), which impairs IFNβ promoter activation by both Sendai virus (SeV) and components implicated in signaling by viral sensors. As a deubiquitinating enzyme (DUB), HBx cleaves Lys63-linked polyubiquitin chains from many proteins except TANK-binding kinase 1 (TBK1). It binds and deconjugates retinoic acid-inducible gene I (RIG I) and TNF receptor-associated factor 3 (TRAF3), causing their dissociation from the downstream adaptor CARDIF or TBK1 kinase. In addition to RIG I and TRAF3, HBx also interacts with CARDIF, TRIF, NEMO, TBK1, inhibitor of kappa light polypeptide gene enhancer in B-cells, kinase epsilon (IKKi) and interferon regulatory factor 3 (IRF3). Our data indicate that multiple points of signaling pathways can be targeted by HBx to negatively regulate production of type I IFN.
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Affiliation(s)
- Junyi Jiang
- Key laboratory of Infection and Immunity of Chinese Academy of Sciences, Institute of Biophysics, Beijing, 100101 China
- Graduate School of Chinese Academy of Sciences, Beijing, 100049 China
| | - Hong Tang
- Key laboratory of Infection and Immunity of Chinese Academy of Sciences, Institute of Biophysics, Beijing, 100101 China
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525
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Lafferty EI, Qureshi ST, Schnare M. The role of toll-like receptors in acute and chronic lung inflammation. JOURNAL OF INFLAMMATION-LONDON 2010; 7:57. [PMID: 21108806 PMCID: PMC3003652 DOI: 10.1186/1476-9255-7-57] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/07/2010] [Accepted: 11/25/2010] [Indexed: 12/13/2022]
Abstract
By virtue of its direct contact with the environment, the lung is constantly challenged by infectious and non-infectious stimuli that necessitate a robust yet highly controlled host response coordinated by the innate and adaptive arms of the immune system. Mammalian Toll-like receptors (TLRs) function as crucial sentinels of microbial and non-infectious antigens throughout the respiratory tract and mediate host innate immunity. Selective induction of inflammatory responses to harmful environmental exposures and tolerance to innocuous antigens are required to maintain tissue homeostasis and integrity. Conversely, dysregulated innate immune responses manifest as sustained and self-perpetuating tissue damage rather than controlled tissue repair. In this article we review aspects of Toll-like receptor function that are relevant to the development of acute lung injury and chronic obstructive lung diseases as well as resistance to frequently associated microbial infections.
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Affiliation(s)
- Erin I Lafferty
- Division of Experimental Medicine, McGill University, Montréal, Québec H3A 1A3, Canada.
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526
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Duan W, Mehta AK, Magalhaes JG, Ziegler SF, Dong C, Philpott DJ, Croft M. Innate signals from Nod2 block respiratory tolerance and program T(H)2-driven allergic inflammation. J Allergy Clin Immunol 2010; 126:1284-93.e10. [PMID: 21051079 DOI: 10.1016/j.jaci.2010.09.021] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2010] [Revised: 09/08/2010] [Accepted: 09/14/2010] [Indexed: 12/14/2022]
Abstract
BACKGROUND Airway tolerance is critical for protecting the lung from inflammatory disease driven by allergens. However, factors that disrupt tolerance processes and then lead to susceptibility to developing allergic asthma remain elusive. OBJECTIVE To investigate whether recognition of bacterial microbial-associated molecular patterns in the lung may result in susceptibility to developing allergic reactions, and to understand the molecular mechanisms by which such triggers block natural tolerance. METHODS Ligands of intracellular microbial-associated molecular pattern recognition receptors-the nucleotide-binding oligomerization domain (Nod)-like receptors, Nod1 and Nod2-were given intranasally with antigen, and their ability to modulate airway tolerance was analyzed. RESULTS Intranasal Nod2 ligand rapidly induced lung expression of the innate cytokines thymic stromal lymphopoietin and IL-25, and thymic stromal lymphopoietin promoted expression of OX40 ligand, a T-cell-costimulatory ligand, on lung CD11c(+)CD11b(+) cells and B220(+) cells. Together these 3 molecules blocked the generation of antigen-specific CD4(+)forkhead box protein 3(+) adaptive regulatory T cells and concomitantly drove IL-4-producing CD4 T cells. By altering the regulatory T/T(H)2-cell balance, tolerance was blocked, and sensing of Nod2 ligand resulted in subsequent susceptibility to developing eosinophil-dominated airway inflammation. CONCLUSION We show that a Nod-like receptor is a novel, previously unrecognized, pathway that adversely links innate and adaptive immunity and leads to allergic disease and asthmatic lung inflammation.
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Affiliation(s)
- Wei Duan
- Division of Molecular Immunology, La Jolla Institute for Allergy and Immunology, La Jolla, CA 92037, USA
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527
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Fritz T, Niederreiter L, Tilg H, Blumberg RS, Kaser A. Controversy over NOD2, inflammation, and defensins. Inflamm Bowel Dis 2010; 16:1996-8. [PMID: 20128000 PMCID: PMC4592164 DOI: 10.1002/ibd.21213] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Simms LA, Doecke JD, Walsh MD, et al. Reduced alpha-defensin expression is associated with inflammation and not NOD2 mutation status in ileal Crohn’s disease. Gut. 2008;57:903–910.
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Affiliation(s)
- Teresa Fritz
- Department of Medicine II, Innsbruck Medical University, Innsbruck, Austria
| | - Lukas Niederreiter
- Department of Medicine II, Innsbruck Medical University, Innsbruck, Austria
| | - Herbert Tilg
- Department of Medicine II, Innsbruck Medical University, Innsbruck, Austria
| | - Richard S. Blumberg
- Division of Gastroenterology, Hepatology and Endoscopy, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts
| | - Arthur Kaser
- Department of Medicine II, Innsbruck Medical University, Innsbruck, Austria
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528
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Mucolytic bacteria with increased prevalence in IBD mucosa augment in vitro utilization of mucin by other bacteria. Am J Gastroenterol 2010; 105:2420-8. [PMID: 20648002 DOI: 10.1038/ajg.2010.281] [Citation(s) in RCA: 958] [Impact Index Per Article: 68.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
OBJECTIVES Mucosa-associated bacteria are increased in inflammatory bowel disease (IBD), which suggests the possibility of an increased source of digestible endogenous mucus substrate. We hypothesized that mucolytic bacteria are increased in IBD, providing increased substrate to sustain nonmucolytic mucosa-associated bacteria. METHODS Mucolytic bacteria were characterized by the ability to degrade human secretory mucin (MUC2) in pure and mixed anaerobic cultures. Real-time PCR was used to enumerate mucosa-associated mucolytic bacteria in 46 IBD and 20 control patients. Bacterial mucolytic activity was tested in vitro using purified human MUC2. RESULTS We confirm increased total mucosa-associated bacteria 16S rRNA gene in macroscopically and histologically normal intestinal epithelium of both Crohn's disease (CD) (mean 1.9-fold) and ulcerative colitis (UC) (mean 1.3-fold). We found a disproportionate increase in some mucolytic bacteria. Mean Ruminococcus gnavus were increased >4-fold and Ruminococcus torques ∼100-fold in macroscopically and histologically normal intestinal epithelium of both CD and UC. The most abundantly detected mucolytic bacterium in controls, Akkermansia muciniphila, was reduced many fold in CD and in UC. Coculture of A. muciniphila with MUC2 as the sole carbon source led to reduction in its abundance while it augmented growth of other bacteria. CONCLUSIONS Mucolytic bacteria are present in healthy humans, where they are an integral part of the mucosa-associated bacterial consortium. The disproportionate increase in R. gnavus and R. torques could explain increased total mucosa-associated bacteria in IBD.
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529
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Genomic profiling of tumor necrosis factor alpha (TNF-alpha) receptor and interleukin-1 receptor knockout mice reveals a link between TNF-alpha signaling and increased severity of 1918 pandemic influenza virus infection. J Virol 2010; 84:12576-88. [PMID: 20926563 DOI: 10.1128/jvi.01310-10] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
The influenza pandemic of 1918 to 1919 was one of the worst global pandemics in recent history. The highly pathogenic nature of the 1918 virus is thought to be mediated in part by a dysregulation of the host response, including an exacerbated proinflammatory cytokine response. In the present study, we compared the host transcriptional response to infection with the reconstructed 1918 virus in wild-type, tumor necrosis factor (TNF) receptor-1 knockout (TNFRKO), and interleukin-1 (IL-1) receptor-1 knockout (IL1RKO) mice as a means of further understanding the role of proinflammatory cytokine signaling during the acute response to infection. Despite reported redundancy in the functions of IL-1β and TNF-α, we observed that reducing the signaling capacity of each of these molecules by genetic disruption of their key receptor genes had very different effects on the host response to infection. In TNFRKO mice, we found delayed or decreased expression of genes associated with antiviral and innate immune signaling, complement, coagulation, and negative acute-phase response. In contrast, in IL1RKO mice numerous genes were differentially expressed at 1 day postinoculation, including an increase in the expression of genes that contribute to dendritic and natural killer cell processes and cellular movement, and gene expression profiles remained relatively constant at later time points. We also observed a compensatory increase in TNF-α expression in virus-infected IL1RKO mice. Our data suggest that signaling through the IL-1 receptor is protective, whereas signaling through the TNF-α receptor increases the severity of 1918 virus infection. These findings suggest that manipulation of these pathways may have therapeutic benefit.
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531
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532
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Abstract
The immune response to viral infections is determined by a complex interplay between the pathogen and the host. Innate immune cells express a set of cytosolic sensors to detect viral infection. Recognition by these sensors induces the production of type I interferons and the assembly of inflammasome complexes that activate caspase-1, leading to production of interleukin-1β (IL-1β) and IL-18. Here, I discuss recent progress in our understanding of the central roles of NOD-like receptors (NLRs) and inflammasomes in the immune response during viral infections. This information will improve our understanding of host defence mechanisms against viruses and provide new avenues for interfering in the pathogenesis of infectious diseases.
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533
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Affiliation(s)
- Rongtuan Lin
- Terry Fox Molecular Oncology Group, Lady Davis Institute for Medical Research, McGill University, Montreal, Canada.
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534
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Li XL, Ezelle HJ, Hsi TY, Hassel BA. A central role for RNA in the induction and biological activities of type 1 interferons. WILEY INTERDISCIPLINARY REVIEWS-RNA 2010; 2:58-78. [PMID: 21956969 DOI: 10.1002/wrna.32] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
In mammals the type 1 interferon (IFN) system functions as the primary innate antiviral defense and more broadly as a stress response and regulator of diverse homeostatic mechanisms. RNA plays a central role in the induction of IFN and in its biologic activities. Cellular toll-like receptors (TLR), RIG-I-like receptors (RLR), and nucleotide organization domain-like receptors (NLR) sense pathogen- and danger-associated RNAs as nonself based on structural features and subcellular location that distinguish them from ubiquitous host RNAs. Detection of nonself RNAs activates signaling pathways to induce IFN transcription and secretion. In turn, IFN binds cell surface receptors to initiate signaling that results in the induction of IFN-stimulated genes (ISGs) that mediate its biologic activities. RNA also plays a critical role in this effector phase of the IFN system, serving as an activator of enzyme activity for protein kinase RNA-dependent (PKR) and oligoadenylate synthetase (OAS), and as a substrate for 2('), 5(') -linked oligoadenylate dependant-endoribonuclease (RNase-L). In contrast to the transcriptional response induced by RNA receptors, these key ISGs mediate their activities primarily through post transcriptional mechanisms to regulate the translation and stability of host and microbial RNAs. Together RNA-sensing and RNA-effector molecules comprise a network of coordinately regulated proteins with integrated feedback and feed-forward loops that tightly regulate the cellular response to RNA. This stringent regulation is essential to prevent deleterious effects of uncontrolled IFN expression and effector activation. In light of this extensive crosstalk, targeting key mediators of the cellular response to RNA represents a viable strategy for therapeutic modulation of immune function and treatment of diseases in which this response is dysregulated (e.g., cancer).
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Affiliation(s)
- Xiao-Ling Li
- Marlene and Stewart Greenebaum Cancer Center, University of Maryland School of Medicine, Baltimore, MD, USA
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535
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Abstract
Viruses are detected by the innate immune system, leading to the initiation of the anti-viral immune response via the production of type I interferons and inflammatory cytokines such as interleukin-1. Remarkable progress has been made over the past few years towards understanding the contribution of Toll-like receptors, RIG-I like receptors, NOD-like receptors and HIN-200 family members to viral detection. Furthermore, new complexities in the signaling pathways activated by these receptors continue to be revealed. Together, these new insights are leading to therapeutically useful information in the fight against viruses.
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Affiliation(s)
- Luke A J O'Neill
- Immunology Research Centre, School of Biochemistry and Immunology, Trinity College Dublin, Dublin 2, Ireland.
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536
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Lecat A, Piette J, Legrand-Poels S. The protein Nod2: an innate receptor more complex than previously assumed. Biochem Pharmacol 2010; 80:2021-31. [PMID: 20643110 DOI: 10.1016/j.bcp.2010.07.016] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2010] [Revised: 07/02/2010] [Accepted: 07/08/2010] [Indexed: 02/08/2023]
Abstract
For almost 10 years, Nod2 has been known as a cytosolic innate receptor able to sense peptidoglycan from Gram-positive and -negative bacteria and to trigger RIP2- and NF-κB-mediated pro-inflammatory and antibacterial response. Mutations in the gene encoding Nod2 in humans have been associated with Crohn's disease (CD). Mechanisms by which Nod2 variants can lead to CD development are still under investigation. The most admitted hypothesis suggests that the impaired function of Nod2 variants in intestinal epithelial and phagocytic cells results in deficiencies in epithelial-barrier function which subsequently lead to increased bacterial invasion and inflammation at intestinal sites. Very recent results have just reinforced this hypothesis by demonstrating that Nod2 wild-type (unlike Nod2 variants) could mediate autophagy, allowing an efficient bacterial clearance and adaptative immune response. Other recent data have attributed new roles to Nod2. Indeed, Nod2 has been shown to activate antiviral innate immune responses involving IRF3-dependent IFN-β production after viral ssRNA recognition through a RIP2-independent mechanism requiring the mitochondrial adaptor protein MAVS. Recently, Nod2 has been also shown to be exquisitely tuned to detect mycobacterial infections and mount a protective immunity against these pathogens.
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Affiliation(s)
- Aurore Lecat
- Laboratory of Virology and Immunology, GIGA-Research, GIGA B34, University of Liège, 4000 Liège, Belgium
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537
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Cadwell K, Patel KK, Maloney NS, Liu TC, Ng ACY, Storer CE, Head RD, Xavier R, Stappenbeck TS, Virgin HW. Virus-plus-susceptibility gene interaction determines Crohn's disease gene Atg16L1 phenotypes in intestine. Cell 2010; 141:1135-45. [PMID: 20602997 DOI: 10.1016/j.cell.2010.05.009] [Citation(s) in RCA: 682] [Impact Index Per Article: 48.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2009] [Revised: 02/26/2010] [Accepted: 04/19/2010] [Indexed: 02/07/2023]
Abstract
It is unclear why disease occurs in only a small proportion of persons carrying common risk alleles of disease susceptibility genes. Here we demonstrate that an interaction between a specific virus infection and a mutation in the Crohn's disease susceptibility gene Atg16L1 induces intestinal pathologies in mice. This virus-plus-susceptibility gene interaction generated abnormalities in granule packaging and unique patterns of gene expression in Paneth cells. Further, the response to injury induced by the toxic substance dextran sodium sulfate was fundamentally altered to include pathologies resembling aspects of Crohn's disease. These pathologies triggered by virus-plus-susceptibility gene interaction were dependent on TNFalpha and IFNgamma and were prevented by treatment with broad spectrum antibiotics. Thus, we provide a specific example of how a virus-plus-susceptibility gene interaction can, in combination with additional environmental factors and commensal bacteria, determine the phenotype of hosts carrying common risk alleles for inflammatory disease.
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Affiliation(s)
- Ken Cadwell
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO 63110, USA
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538
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Vandevenne P, Sadzot-Delvaux C, Piette J. Innate immune response and viral interference strategies developed by human herpesviruses. Biochem Pharmacol 2010; 80:1955-72. [PMID: 20620129 DOI: 10.1016/j.bcp.2010.07.001] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2010] [Revised: 07/01/2010] [Accepted: 07/01/2010] [Indexed: 12/24/2022]
Abstract
Viruses are by far the most abundant parasites on earth and they have been found to infect animals, plants and bacteria. However, different types of viruses can only infect a limited range of hosts and many are species-specific. Herpesviruses constitute a large family of DNA viruses that cause diseases in animals, including humans and that are known to undergo lytic or latent infections. Consequently, they developed numerous strategies to counteract host antiviral responses to escape immune surveillance. Innate immune response constitutes the first line of host defence that limits the viral spread and also plays an important role in the activation of adaptive immune response. Viral components are recognized by specific host Pathogen Recognition Receptors (PRRs) which trigger the activation of IRF3, NF-κB and AP-1, three regulators of IFN-β expression. IFN-β is responsible for the induction of Interferon-Stimulated Genes (ISGs) that encode antiviral effectors important to limit the viral spread and to establish an antiviral state as well in the infected cells as in the neighbouring non-infected cells. In this review, we will summarize how host cells recognize viral components and activate downstream signalling pathways leading to the production of IFN-β and ISGs. We will also review the most recent findings in Herpesviruses-encoded proteins involved in host immune evasion.
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Affiliation(s)
- Patricia Vandevenne
- Laboratory of Virology and Immunology, GIGA-Research B34, University of Liège, B-4000 Liège, Belgium
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539
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Neerincx A, Lautz K, Menning M, Kremmer E, Zigrino P, Hösel M, Büning H, Schwarzenbacher R, Kufer TA. A role for the human nucleotide-binding domain, leucine-rich repeat-containing family member NLRC5 in antiviral responses. J Biol Chem 2010; 285:26223-32. [PMID: 20538593 DOI: 10.1074/jbc.m110.109736] [Citation(s) in RCA: 133] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Proteins of the nucleotide-binding domain, leucine-rich repeat (NLR)-containing family recently gained attention as important components of the innate immune system. Although over 20 of these proteins are present in humans, only a few members including the cytosolic pattern recognition receptors NOD1, NOD2, and NLRP3 have been analyzed extensively. These NLRs were shown to be pivotal for mounting innate immune response toward microbial invasion. Here we report on the characterization of human NLRC5 and provide evidence that this NLR has a function in innate immune responses. We found that NLRC5 is a cytosolic protein expressed predominantly in hematopoetic cells. NLRC5 mRNA and protein expression was inducible by the double-stranded RNA analog poly(I.C) and Sendai virus. Overexpression of NLRC5 failed to trigger inflammatory responses such as the NF-kappaB or interferon pathways in HEK293T cells. However, knockdown of endogenous NLRC5 reduced Sendai virus- and poly(I.C)-mediated type I interferon pathway-dependent responses in THP-1 cells and human primary dermal fibroblasts. Taken together, this defines a function for NLRC5 in anti-viral innate immune responses.
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Affiliation(s)
- Andreas Neerincx
- Institute for Medical Microbiology, Immunology and Hygiene, University of Cologne, Cologne, Germany
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540
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Brennan K, Bowie AG. Activation of host pattern recognition receptors by viruses. Curr Opin Microbiol 2010; 13:503-7. [PMID: 20538506 DOI: 10.1016/j.mib.2010.05.007] [Citation(s) in RCA: 102] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2010] [Accepted: 05/18/2010] [Indexed: 12/25/2022]
Abstract
Viral recognition by the host innate immune system has become an exciting and growing area of research focus in recent years. It is now apparent that multiple pattern recognition receptor (PRR) families, including Toll-like receptors (TLRs), RIG-I-like receptors (RLRs) and NOD-like receptors (NLRs), contribute significantly to viral detection by sensing viral proteins and nucleic acids, leading to induction of cytokines and type I interferons (IFNs). Of particular current interest is the sensing of viral DNA within infected cells, since the PRRs responsible for this are only partially defined. Recently RNA polymerase III (Pol III) was shown to transcribe some viral DNAs into RNA for detection by RIG-I, leading to IFN induction. Another novel mechanism of viral DNA recognition unveiled, leading to proinflammatory cytokine production, involves the PYHIN family member AIM2.
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Affiliation(s)
- Kiva Brennan
- School of Biochemistry & Immunology, Trinity College Dublin, Dublin 2, Ireland
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541
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Abstract
Unanchored chains of ubiquitin molecules control a cell signaling pathway that responds to viral infection.
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Affiliation(s)
- Kislay Parvatiyar
- Department of Microbiology and Immunology, Sylvester Comprehensive Cancer Center, Miller School of Medicine, University of Miami, Miami, FL 33136, USA
| | - Edward W. Harhaj
- Department of Microbiology and Immunology, Sylvester Comprehensive Cancer Center, Miller School of Medicine, University of Miami, Miami, FL 33136, USA
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542
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Blanco JCG, Boukhvalova MS, Shirey KA, Prince GA, Vogel SN. New insights for development of a safe and protective RSV vaccine. HUMAN VACCINES 2010; 6:482-92. [PMID: 20671419 PMCID: PMC2965816 DOI: 10.4161/hv.6.6.11562] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Respiratory Syncytial Virus (RSV) is the leading cause of pneumonia and bronchiolitis in infants and children <1 year old, resulting in significant morbidity and mortality worldwide. There is currently no RSV vaccine. In the 1960s, a formalin-inactivated RSV (FI-RSV) vaccine trial led to exacerbated disease upon natural infection of vaccinees, including two deaths. The causes involved in the disastrous results of these vaccine trials are still unclear but they remain the engine for searching new avenues to develop a safe vaccine that can provide long-term protection against this important pathogen. This article reviews some of the early history of RSV vaccine development,as well as more recent information on the interaction between RSV and the host innate and adaptive immune responses. A safe and efficacious vaccine for RSV will require "re-education" of the host immune response against RSV to prevent vaccine-enhanced or severe RSV disease.
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543
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McGuckin MA, Eri RD, Das I, Lourie R, Florin TH. ER stress and the unfolded protein response in intestinal inflammation. Am J Physiol Gastrointest Liver Physiol 2010; 298:G820-32. [PMID: 20338921 DOI: 10.1152/ajpgi.00063.2010] [Citation(s) in RCA: 145] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Endoplasmic reticulum (ER) stress is a phenomenon that occurs when excessive protein misfolding occurs during biosynthesis. ER stress triggers a series of signaling and transcriptional events known as the unfolded protein response (UPR). The UPR attempts to restore homeostasis in the ER but if unsuccessful can trigger apoptosis in the stressed cells and local inflammation. Intestinal secretory cells are susceptible to ER stress because they produce large amounts of complex proteins for secretion, most of which are involved in mucosal defense. This review focuses on ER stress in intestinal secretory cells and describes how increased protein misfolding could occur in these cells, the process of degradation of misfolded proteins, the major molecular elements of the UPR pathway, and links between the UPR and inflammation. Evidence is reviewed from mouse models and human inflammatory bowel diseases that ties ER stress and activation of the UPR with intestinal inflammation, and possible therapeutic approaches to ameliorate ER stress are discussed.
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Affiliation(s)
- Michael A McGuckin
- Mucosal Diseases Program, Mater Medical Research Institute, Mater Health Services, South Brisbane, Qld 4029, Australia.
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544
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Abstract
Insights into inflammatory bowel disease (IBD) are advancing rapidly owing to immunologic investigations of a plethora of animal models of intestinal inflammation, ground-breaking advances in the interrogation of diseases that are inherited as complex genetic traits, and the development of culture-independent methods to define the composition of the intestinal microbiota. These advances are bringing a deeper understanding to the genetically determined interplay between the commensal microbiota, intestinal epithelial cells, and the immune system and the manner in which this interplay might be modified by relevant environmental factors in the pathogenesis of IBD. This review examines these interactions and, where possible, potential lessons from IBD-directed, biologic therapies that may allow for elucidation of pathways that are central to disease pathogenesis in humans.
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Affiliation(s)
- Arthur Kaser
- Department of Medicine II, Medical University Innsbruck, Austria
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545
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Abstract
Insights into inflammatory bowel disease (IBD) are advancing rapidly owing to immunologic investigations of a plethora of animal models of intestinal inflammation, ground-breaking advances in the interrogation of diseases that are inherited as complex genetic traits, and the development of culture-independent methods to define the composition of the intestinal microbiota. These advances are bringing a deeper understanding to the genetically determined interplay between the commensal microbiota, intestinal epithelial cells, and the immune system and the manner in which this interplay might be modified by relevant environmental factors in the pathogenesis of IBD. This review examines these interactions and, where possible, potential lessons from IBD-directed, biologic therapies that may allow for elucidation of pathways that are central to disease pathogenesis in humans.
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Affiliation(s)
- Arthur Kaser
- Department of Medicine II, Medical University Innsbruck, Austria
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546
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Abstract
Type I interferons (IFNs) are secreted cytokines that orchestrate diverse immune responses to infection. Although typically considered to be most important in the response to viruses, type I IFNs are also induced by most, if not all, bacterial pathogens. Although diverse mechanisms have been described, bacterial induction of type I IFNs occurs upon stimulation of two main pathways: (i) Toll-like receptor (TLR) recognition of bacterial molecules such as lipopolysaccharide (LPS); (ii) TLR-independent recognition of molecules delivered to the host cell cytosol. Cytosolic responses can be activated by two general mechanisms. First, viable bacteria can secrete stimulatory ligands into the cytosol via specialized bacterial secretion systems. Second, ligands can be released from bacteria that lyse or are degraded. The bacterial ligands that induce the cytosolic pathways remain uncertain in many cases, but appear to include various nucleic acids. In this review, we discuss recent advances in our understanding of how bacteria induce type I interferons and the roles type I IFNs play in host immunity.
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Affiliation(s)
- Kathryn M Monroe
- Division of Immunology and Pathogenesis, Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA
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547
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Kumagai Y, Akira S. Identification and functions of pattern-recognition receptors. J Allergy Clin Immunol 2010; 125:985-92. [DOI: 10.1016/j.jaci.2010.01.058] [Citation(s) in RCA: 147] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2009] [Revised: 01/08/2010] [Accepted: 01/12/2010] [Indexed: 12/25/2022]
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548
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Charrière GM, Ip WE, Dejardin S, Boyer L, Sokolovska A, Cappillino MP, Cherayil BJ, Podolsky DK, Kobayashi KS, Silverman N, Lacy-Hulbert A, Stuart LM. Identification of Drosophila Yin and PEPT2 as evolutionarily conserved phagosome-associated muramyl dipeptide transporters. J Biol Chem 2010; 285:20147-54. [PMID: 20406817 DOI: 10.1074/jbc.m110.115584] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
NOD2 (nucleotide-binding oligomerization domain containing 2) is an important cytosolic pattern recognition receptor that activates NF-kappaB and other immune effector pathways such as autophagy and antigen presentation. Despite its intracellular localization, NOD2 participates in sensing of extracellular microbes such as Staphylococcus aureus. NOD2 ligands similar to the minimal synthetic ligand muramyl dipeptide (MDP) are generated by internalization and processing of bacteria in hydrolytic phagolysosomes. However, how these derived ligands exit this organelle and access the cytosol to activate NOD2 is poorly understood. Here, we address how phagosome-derived NOD2 ligands access the cytosol in human phagocytes. Drawing on data from Drosophila phagosomes, we identify an evolutionarily conserved role of SLC15A transporters, Drosophila Yin and PEPT2, as MDP transporters in fly and human phagocytes, respectively. We show that PEPT2 is highly expressed by human myeloid cells. Ectopic expression of both Yin and PEPT2 increases the sensitivity of NOD2-dependent NF-kappaB activation. Additionally, we show that PEPT2 associates with phagosome membranes. Together, these data identify Drosophila Yin and PEPT2 as evolutionarily conserved phagosome-associated transporters that are likely to be of particular importance in delivery of bacteria-derived ligands generated in phagosomes to cytosolic sensors recruited to the vicinity of these organelles.
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Affiliation(s)
- Guillaume M Charrière
- Developmental Immunology, Massachusetts General Hospital/Harvard Medical School, 55 Fruit St., Boston, MA 02114, USA
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549
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Sumpter R, Levine B. Autophagy and innate immunity: triggering, targeting and tuning. Semin Cell Dev Biol 2010; 21:699-711. [PMID: 20403453 DOI: 10.1016/j.semcdb.2010.04.003] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2010] [Revised: 04/06/2010] [Accepted: 04/08/2010] [Indexed: 02/06/2023]
Abstract
Autophagy is a conserved catabolic stress response pathway that is increasingly recognized as an important component of both innate and acquired immunity to pathogens. The activation of autophagy during infection not only provides cell-autonomous protection through lysosomal degradation of invading pathogens (xenophagy), but also regulates signaling by other innate immune pathways. This review will focus on recent advances in our understanding of three major areas of the interrelationship between autophagy and innate immunity, including how autophagy is triggered during infection, how invading pathogens are targeted to autophagosomes, and how the autophagy pathway participates in "tuning" the innate immune response.
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Affiliation(s)
- Rhea Sumpter
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
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550
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Shaw PJ, Lamkanfi M, Kanneganti TD. NOD-like receptor (NLR) signaling beyond the inflammasome. Eur J Immunol 2010; 40:624-7. [PMID: 20201016 DOI: 10.1002/eji.200940211] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Recent years have witnessed a marked progress in our knowledge of NOD-like receptors (NLR), intracellular sensors with central roles in innate and adaptive immunity. A majority of the research has focused on caspase-1 inflammasomes. However, several members of the mammalian NLR family exert important roles in immunity beyond inflammasome signaling. Here we highlight the emerging roles of several of these NLR.
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Affiliation(s)
- Patrick J Shaw
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN 38105-2794, USA
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