801
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Sanghavi SK, Reinhart TA. Increased expression of TLR3 in lymph nodes during simian immunodeficiency virus infection: implications for inflammation and immunodeficiency. THE JOURNAL OF IMMUNOLOGY 2005; 175:5314-23. [PMID: 16210637 DOI: 10.4049/jimmunol.175.8.5314] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
As pattern recognition receptors, TLRs signal and induce expression of multiple host defense genes including proinflammatory cytokines and chemokines. To investigate the mechanisms of up-regulation of proinflammatory cytokines and chemokines during SIV infection in rhesus macaques, we measured the relative levels of expression of TLRs 1-10 in lymphoid tissues during different stages of SIV infection. By real-time RT-PCR, TLR3 was determined to be up-regulated in macaque lymph nodes (LN) throughout the course of infection, whereas TLR9 was down-regulated during early stages of infection. CXCL9/Mig, CXCL10/IP-10, IFN-gamma, and IFN-alpha mRNAs were also increased during acute SIV infection and AIDS. Treatment of macaque spleen and LN cells with TLR3 and TLR9 ligands led to the induction of these same genes. TLR3 stimulation had disparate effects on viral transcription and viral replication, because poly(I:C), a model TLR3 ligand, stimulated the viral promoter but potently inhibited SIV replication in primary cultures of macaque spleen and LN cells. These findings identify roles for TLR3 inflammation in lymphoid tissues and in the immunopathogenesis of HIV-1/SIV, and suggest that TLR3 ligands could potentially be used to flush out latently infected cells that persist during antiretroviral therapies.
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Affiliation(s)
- Sonali K Sanghavi
- Department of Infectious Diseases and Microbiology, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA 15261, USA
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802
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Garcia-Tapia D, Loiacono CM, Kleiboeker SB. Replication of West Nile virus in equine peripheral blood mononuclear cells. Vet Immunol Immunopathol 2005; 110:229-44. [PMID: 16310859 DOI: 10.1016/j.vetimm.2005.10.003] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2005] [Accepted: 10/05/2005] [Indexed: 10/25/2022]
Abstract
A cell model of primary monocytes and other mononuclear cells isolated from equine blood was used to study the kinetics of West Nile virus (WNV) replication in a natural host. West Nile virus has emerged on the North American continent as a significant cause of morbidity and mortality in a wide range of avian and mammalian species. While other flaviviruses are known to infect monocytes and lymphocytes, the ability of WNV to productively replicate in specific immune cells of peripheral blood has not been assessed. In this study, enriched populations of monocytes and lymphocytes as well as purified monocytes, CD4+, CD8+ and B lymphocytes were obtained from equine blood. Productive WNV replication was demonstrated by viral growth curves, quantitative RT-PCR for WNV RNA, and indirect immunofluorescence detection of a non-structural WNV protein. Enriched and purified monocytes consistently supported productive viral replication in blood from nine of nine horses tested while a minor subset of CD4+ lymphocytes supported productive replication in cells from three of the nine horses tested. Peak viral titers of 3.2-6.6 log10 PFU/ml were reached at 6 days post-inoculation (p.i.) and titers were maintained through 10-15 days p.i. Activation of monocytes with bacterial lipopolysaccharide, which resulted in activation of nuclear transcription factor kappaB (NF-kappaB) plus elevation of nitric oxide and type I interferon levels, reduced or eliminated WNV replication. These results suggest that immune cells of the peripheral blood may serve as target cells for initial replication of WNV and may play a role in subsequent viral dissemination. Furthermore, primary equine immune cell cultures represent a potentially useful model of a natural WNV host when testing compounds such as antivirals for use in WNV treatment.
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Affiliation(s)
- David Garcia-Tapia
- Department of Veterinary Pathobiology, College of Veterinary Medicine, University of Missouri, Columbia, MO 65211, USA
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803
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Samuel MA, Diamond MS. Alpha/beta interferon protects against lethal West Nile virus infection by restricting cellular tropism and enhancing neuronal survival. J Virol 2005; 79:13350-61. [PMID: 16227257 PMCID: PMC1262587 DOI: 10.1128/jvi.79.21.13350-13361.2005] [Citation(s) in RCA: 328] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
West Nile virus (WNV) is a mosquito-borne flavivirus that is neurotropic in humans, birds, and other animals. While adaptive immunity plays an important role in preventing WNV spread to the central nervous system (CNS), little is known about how alpha/beta interferon (IFN-alpha/beta) protects against peripheral and CNS infection. In this study, we examine the virulence and tropism of WNV in IFN-alpha/beta receptor-deficient (IFN- alpha/betaR-/-) mice and primary neuronal cultures. IFN-alpha/betaR-/- mice were acutely susceptible to WNV infection through subcutaneous inoculation, with 100% mortality and a mean time to death (MTD) of 4.6 +/- 0.7 and 3.8+/- 0.5 days after infection with 10(0) and 10(2) PFU, respectively. In contrast, congenic wild-type 129Sv/Ev mice infected with 10(2) PFU showed 62% mortality and a MTD of 11.9 +/- 1.9 days. IFN-alpha/betaR-/- mice developed high viral loads by day 3 after infection in nearly all tissues assayed, including many that were not infected in wild-type mice. IFN-alpha/betaR-/- mice also demonstrated altered cellular tropism, with increased infection in macrophages, B cells, and T cells in the spleen. Additionally, treatment of primary wild-type neurons in vitro with IFN-beta either before or after infection increased neuronal survival independent of its effect on WNV replication. Collectively, our data suggest that IFN-alpha/beta controls WNV infection by restricting tropism and viral burden and by preventing death of infected neurons.
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Affiliation(s)
- Melanie A Samuel
- Department of Molecular Microbiology, Washington University School of Medicine, Campus Box 8051, 660 S. Euclid Ave., St. Louis, MO 63110, USA
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804
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Okahira S, Nishikawa F, Nishikawa S, Akazawa T, Seya T, Matsumoto M. Interferon-beta induction through toll-like receptor 3 depends on double-stranded RNA structure. DNA Cell Biol 2005; 24:614-23. [PMID: 16225392 DOI: 10.1089/dna.2005.24.614] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Type I interferons (IFN-alpha/beta) play an essential role in both innate and adaptive antiviral immune responses. IFN- beta is produced by fibroblasts and myeloid dendritic cells (DCs) upon viral infection or in response to doublestranded RNA (dsRNA). Several intracellular molecules having a dsRNA-binding motif such as dsRNA-dependent protein kinase recognize dsRNA in a sequence-independent manner and induce antiviral innate responses. Toll-like receptor (TLR) 3, a member of TLR family proteins, recognizes extracellular dsRNA and activates NF- kappaB and the IFN-beta promoter leading to the induction of IFN-beta production. Here we analyzed the dsRNA structure capable of inducing TLR3-mediated IFN-beta production using various synthetic RNA duplexes. In contrast to the recognition of dsRNA by intracellular molecules, TLR3 preferentially recognizes polyriboinocinic:polyribocytidylic acid (poly(I:C)) rather than synthetic virus-derived dsRNAs. 2'-O-methyl or 2'-fluoro modification of cytidylic acid abolished the IFN-beta-inducing ability of the poly(I:C) duplex, and these modified dsRNAs inhibited poly(I:C)-induced TLR3-mediated IFN-beta production by fibroblasts and DCs. In addition, poly(dI:dC), a non-IFN inducer, also blocked poly(I:C)-induced IFN-beta induction. Since TLR3 is localized in the intracellular compartment of DCs where signaling occurs, modified dsRNAs may compete with poly(I:C) for binding to the cell-surface receptor that transfers dsRNA into TLR3-enriched vesicles. Thus, TLR3 recognizes a unique dsRNA structure that largely differs from those recognized by other dsRNA-binding proteins.
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Affiliation(s)
- Satoyo Okahira
- Department of Immunology, Osaka Medical Center for Cancer and Cardiovascular Diseases, Higashinari-ku, Osaka, Japan
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805
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Yang K, Puel A, Zhang S, Eidenschenk C, Ku CL, Casrouge A, Picard C, von Bernuth H, Senechal B, Plancoulaine S, Al-Hajjar S, Al-Ghonaium A, Maródi L, Davidson D, Speert D, Roifman C, Garty BZ, Ozinsky A, Barrat FJ, Coffman RL, Miller RL, Li X, Lebon P, Rodriguez-Gallego C, Chapel H, Geissmann F, Jouanguy E, Casanova JL. Human TLR-7-, -8-, and -9-mediated induction of IFN-alpha/beta and -lambda Is IRAK-4 dependent and redundant for protective immunity to viruses. Immunity 2005; 23:465-78. [PMID: 16286015 PMCID: PMC7111074 DOI: 10.1016/j.immuni.2005.09.016] [Citation(s) in RCA: 198] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2005] [Revised: 09/16/2005] [Accepted: 09/22/2005] [Indexed: 12/11/2022]
Abstract
Five TLRs are thought to play an important role in antiviral immunity, sensing viral products and inducing IFN-alpha/beta and -lambda. Surprisingly, patients with a defect of IRAK-4, a critical kinase downstream from TLRs, are resistant to common viruses. We show here that IFN-alpha/beta and -lambda induction via TLR-7, TLR-8, and TLR-9 was abolished in IRAK-4-deficient blood cells. In contrast, IFN-alpha/beta and -lambda were induced normally by TLR-3 and TLR-4 agonists. Moreover, IFN-beta and -lambda were normally induced by TLR-3 agonists and viruses in IRAK-4-deficient fibroblasts. We further show that IFN-alpha/beta and -lambda production in response to 9 of 11 viruses tested was normal or weakly affected in IRAK-4-deficient blood cells. Thus, IRAK-4-deficient patients may control viral infections by TLR-3- and TLR-4-dependent and/or TLR-independent production of IFNs. The TLR-7-, TLR-8-, and TLR-9-dependent induction of IFN-alpha/beta and -lambda is strictly IRAK-4 dependent and paradoxically redundant for protective immunity to most viruses in humans.
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Affiliation(s)
- Kun Yang
- Laboratory of Human Genetics of Infectious Diseases, University of Paris René Descartes INSERM U550, Necker Medical School, 75015 Paris, France
- French-Chinese Laboratory of Genetics and Life Sciences, Rui Jin Hospital, Medical School of Shanghai Jiao Tong University, 200025 Shanghai, China
| | - Anne Puel
- Laboratory of Human Genetics of Infectious Diseases, University of Paris René Descartes INSERM U550, Necker Medical School, 75015 Paris, France
| | - Shenying Zhang
- Laboratory of Human Genetics of Infectious Diseases, University of Paris René Descartes INSERM U550, Necker Medical School, 75015 Paris, France
- French-Chinese Laboratory of Genetics and Life Sciences, Rui Jin Hospital, Medical School of Shanghai Jiao Tong University, 200025 Shanghai, China
| | - Céline Eidenschenk
- Laboratory of Human Genetics of Infectious Diseases, University of Paris René Descartes INSERM U550, Necker Medical School, 75015 Paris, France
| | - Cheng-Lung Ku
- Laboratory of Human Genetics of Infectious Diseases, University of Paris René Descartes INSERM U550, Necker Medical School, 75015 Paris, France
| | - Armanda Casrouge
- Laboratory of Human Genetics of Infectious Diseases, University of Paris René Descartes INSERM U550, Necker Medical School, 75015 Paris, France
| | - Capucine Picard
- Laboratory of Human Genetics of Infectious Diseases, University of Paris René Descartes INSERM U550, Necker Medical School, 75015 Paris, France
- Pediatric Immunology-Hematology, Necker Enfants Malades Hospital, 75015 Paris, France
| | - Horst von Bernuth
- Laboratory of Human Genetics of Infectious Diseases, University of Paris René Descartes INSERM U550, Necker Medical School, 75015 Paris, France
| | - Brigitte Senechal
- Laboratory of Mononuclear Cell Biology, INSERM Avenir, IFR Necker, Necker Hospital, 75015 Paris, France
| | - Sabine Plancoulaine
- Laboratory of Human Genetics of Infectious Diseases, University of Paris René Descartes INSERM U550, Necker Medical School, 75015 Paris, France
| | - Sami Al-Hajjar
- Department of Pediatrics, King Faisal Specialist Hospital and Research Center, Riyadh 11211, Kingdom of Saudi Arabia
| | - Abdulaziz Al-Ghonaium
- Department of Pediatrics, King Faisal Specialist Hospital and Research Center, Riyadh 11211, Kingdom of Saudi Arabia
| | - László Maródi
- Department of Infectiology and Pediatric Immunology, Medical and Health Science Center, University of Debrecen, H-4012 Debrecen, Hungary
| | - Donald Davidson
- Division of Infectious and Immunological Diseases, British Columbia Research Institute for Child and Family Health, Vancouver, British Columbia V5Z 4H4, Canada
| | - David Speert
- Division of Infectious and Immunological Diseases, British Columbia Research Institute for Child and Family Health, Vancouver, British Columbia V5Z 4H4, Canada
| | - Chaim Roifman
- Divison of Immunology/Allergy, Department of Paediatrics, Hospital for Sick Children, University of Toronto, Toronto, Ontario M5G 1X8, Canada
| | - Ben-Zion Garty
- Department of Pediatrics, Schneider Children's Medical Center of Israel, 49202 Petah Tiqva, Israel
| | - Adrian Ozinsky
- Institute for Systems Biology, Seattle, Washington 98103
| | | | | | | | - Xiaoxia Li
- Department of Immunology, Cleveland Clinic Foundation, Cleveland, Ohio 44195
| | - Pierre Lebon
- Department of Virology, Saint Vincent de Paul Hospital, University of Paris René Descartes, 75015 Paris, France
| | - Carlos Rodriguez-Gallego
- Department of Immunology, Gran Canaria Dr Negrin Hospital, 35020 Las Palmas de Gran Canaria, Spain
| | - Helen Chapel
- Department of Immunology, Oxford Radcliffe Hospital, John Radcliffe Campus, Headington, Oxford OX3 9DU, United Kingdom
| | - Frédéric Geissmann
- Laboratory of Mononuclear Cell Biology, INSERM Avenir, IFR Necker, Necker Hospital, 75015 Paris, France
| | - Emmanuelle Jouanguy
- Laboratory of Human Genetics of Infectious Diseases, University of Paris René Descartes INSERM U550, Necker Medical School, 75015 Paris, France
- French-Chinese Laboratory of Genetics and Life Sciences, Rui Jin Hospital, Medical School of Shanghai Jiao Tong University, 200025 Shanghai, China
| | - Jean-Laurent Casanova
- Laboratory of Human Genetics of Infectious Diseases, University of Paris René Descartes INSERM U550, Necker Medical School, 75015 Paris, France
- French-Chinese Laboratory of Genetics and Life Sciences, Rui Jin Hospital, Medical School of Shanghai Jiao Tong University, 200025 Shanghai, China
- Pediatric Immunology-Hematology, Necker Enfants Malades Hospital, 75015 Paris, France
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806
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Town T, Nikolic V, Tan J. The microglial "activation" continuum: from innate to adaptive responses. J Neuroinflammation 2005; 2:24. [PMID: 16259628 PMCID: PMC1298325 DOI: 10.1186/1742-2094-2-24] [Citation(s) in RCA: 333] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2005] [Accepted: 10/31/2005] [Indexed: 12/25/2022] Open
Abstract
Microglia are innate immune cells of myeloid origin that take up residence in the central nervous system (CNS) during embryogenesis. While classically regarded as macrophage-like cells, it is becoming increasingly clear that reactive microglia play more diverse roles in the CNS. Microglial "activation" is often used to refer to a single phenotype; however, in this review we consider that a continuum of microglial activation exists, with phagocytic response (innate activation) at one end and antigen presenting cell function (adaptive activation) at the other. Where activated microglia fall in this spectrum seems to be highly dependent on the type of stimulation provided. We begin by addressing the classical roles of peripheral innate immune cells including macrophages and dendritic cells, which seem to define the edges of this continuum. We then discuss various types of microglial stimulation, including Toll-like receptor engagement by pathogen-associated molecular patterns, microglial challenge with myelin epitopes or Alzheimer's β-amyloid in the presence or absence of CD40L co-stimulation, and Alzheimer disease "immunotherapy". Based on the wide spectrum of stimulus-specific microglial responses, we interpret these cells as immune cells that demonstrate remarkable plasticity following activation. This interpretation has relevance for neurodegenerative/neuroinflammatory diseases where reactive microglia play an etiological role; in particular viral/bacterial encephalitis, multiple sclerosis and Alzheimer disease.
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Affiliation(s)
- Terrence Town
- Section of Immunobiology, Yale University School of Medicine, 300 Cedar St., New Haven, CT 06520-8011, USA
- Neuroimmunology Laboratory, Silver Child Development Center, Department of Psychiatry and Behavioral Medicine, University of South Florida, 3515 E. Fletcher Ave., Tampa, FL 33613, USA
| | - Veljko Nikolic
- Neuroimmunology Laboratory, Silver Child Development Center, Department of Psychiatry and Behavioral Medicine, University of South Florida, 3515 E. Fletcher Ave., Tampa, FL 33613, USA
| | - Jun Tan
- Neuroimmunology Laboratory, Silver Child Development Center, Department of Psychiatry and Behavioral Medicine, University of South Florida, 3515 E. Fletcher Ave., Tampa, FL 33613, USA
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807
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Shingai M, Inoue N, Okuno T, Okabe M, Akazawa T, Miyamoto Y, Ayata M, Honda K, Kurita-Taniguchi M, Matsumoto M, Ogura H, Taniguchi T, Seya T. Wild-type measles virus infection in human CD46/CD150-transgenic mice: CD11c-positive dendritic cells establish systemic viral infection. THE JOURNAL OF IMMUNOLOGY 2005; 175:3252-61. [PMID: 16116216 DOI: 10.4049/jimmunol.175.5.3252] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
We generated transgenic (TG) mice that constitutively express human CD46 (huCD46) and/or TLR-inducible CD150 (huCD150), which serve as receptors for measles virus (MV). These mice were used to study the spreading and pathogenicity of GFP-expressing or intact laboratory-adapted Edmonston and wild-type Ichinose (IC) strains of MV. Irrespective of the route of administration, neither type of MV was pathogenic to these TG mice. However, in ex vivo, limited replication of IC was observed in the spleen lymphocytes from huCD46/huCD150 TG and huCD150 TG, but not in huCD46 TG and non-TG mice. In huCD150-positive TG mouse cells, CD11c-positive bone marrow-derived myeloid dendritic cells (mDC) participated in MV-mediated type I IFN induction. The level and induction profile of IFN-beta was higher in mDC than the profile of IFN-alpha. Wild-type IC induced markedly high levels of IFN-beta compared with Edmonston in mDC, as opposed to human dendritic cells. We then generated huCD46/huCD150 TG mice with type I IFN receptor (IFNAR1)-/- mice. MV-bearing mDCs spreading to draining lymph nodes were clearly observed in these triple mutant mice in vivo by i.p. MV injection. Infectious lymph nodes were also detected in the double TG mice into which MV-infected CD11c-positive mDCs were i.v. transferred. This finding suggests that in the double TG mouse model mDCs once infected facilitate systemic MV spreading and infection, which depend on mDC MV permissiveness determined by the level of type I IFN generated via IFNAR1. Although these results may not simply reflect human MV infection, the huCD150/huCD46 TG mice may serve as a useful model for the analysis of MV-dependent modulation of mDC response.
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Affiliation(s)
- Masashi Shingai
- Department of Immunology, Osaka Medical Center for Cancer and Cardiovascular Diseases, Osaka, Japan
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808
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Hayes EB, Sejvar JJ, Zaki SR, Lanciotti RS, Bode AV, Campbell GL. Virology, pathology, and clinical manifestations of West Nile virus disease. Emerg Infect Dis 2005; 11:1174-9. [PMID: 16102303 PMCID: PMC3320472 DOI: 10.3201/eid1108.050289b] [Citation(s) in RCA: 293] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Virologic characteristics of WNV likely interact with host factors in the pathogenesis of fever, meningitis, encephalitis, and flaccid paralysis. West Nile virus (WNV) causes epidemics of febrile illness, meningitis, encephalitis, and flaccid paralysis. Since it was first detected in New York City in 1999, and through 2004, 16,000 WNV disease cases have been reported in the United States. Over the past 5 years, research on WNV disease has expanded rapidly. This review highlights new information regarding the virology, clinical manifestations, and pathology of WNV disease, which will provide a new platform for further research into diagnosis, treatment, and possible prevention of WNV through vaccination.
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Affiliation(s)
- Edward B Hayes
- Centers for Disease Control and Prevention, Fort Collins, Colorado 80526, USA.
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809
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Rasschaert J, Ladrière L, Urbain M, Dogusan Z, Katabua B, Sato S, Akira S, Gysemans C, Mathieu C, Eizirik DL. Toll-like Receptor 3 and STAT-1 Contribute to Double-stranded RNA+ Interferon-γ-induced Apoptosis in Primary Pancreatic β-Cells. J Biol Chem 2005; 280:33984-91. [PMID: 16027122 DOI: 10.1074/jbc.m502213200] [Citation(s) in RCA: 129] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Viral infections and local production of cytokines probably contribute to the pathogenesis of Type 1 diabetes. The viral replicative intermediate double-stranded RNA (dsRNA, tested in the form of polyinosinic-polycytidylic acid, PIC), in combination with the cytokine interferon-gamma (IFN-gamma), triggers beta-cell apoptosis. We have previously observed by microarray analysis that PIC induces expression of several mRNAs encoding for genes downstream of Toll-like receptor 3 (TLR3) signaling pathway. In this report, we show that exposure of beta-cells to dsRNA in combination with IFN-alpha, -beta, or -gamma significantly increases apoptosis. Moreover, dsRNA induces TLR3 mRNA expression and activates NF-kappaB and the IFN-beta promoter in a TRIF-dependent manner. dsRNA also induces an early (1 h) and sustained increase in IFN-beta mRNA expression, and blocking IFN-beta with a specific antibody partially prevents PIC plus IFN-gamma-induced beta-cell death. On the other hand, dsRNA plus IFN-gamma does not induce apoptosis in INS-1E cells, and expression of TLR3 and type I IFNs mRNAs is not detected in these cells. Of note, disruption of the STAT-1 signaling pathway protects beta-cells against dsRNA plus IFN-gamma-induced beta-cell apoptosis. This study suggests that dsRNA plus IFN-gamma triggers beta-cell apoptosis by two complementary pathways, namely TLR3-TRIF-NF-kappaB and STAT-1.
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Affiliation(s)
- Joanne Rasschaert
- Laboratory of Experimental Medicine, Université Libre de Bruxelles, Route de Lennik, 808, CP 618, B-1070 Brussels, Belgium.
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810
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Rodriguez MF, Wiens GD, Purcell MK, Palti Y. Characterization of Toll-like receptor 3 gene in rainbow trout (Oncorhynchus mykiss). Immunogenetics 2005; 57:510-9. [PMID: 16086174 DOI: 10.1007/s00251-005-0013-1] [Citation(s) in RCA: 118] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2005] [Accepted: 05/31/2005] [Indexed: 12/12/2022]
Abstract
Antiviral immunity in fish is not well understood. In mammals, Toll-like receptor (TLR) 3 is involved in double-stranded RNA recognition and host immune response activation. Here, we report the first identification of a rainbow trout TLR3 ortholog (rtTLR3), its genomic structure, and mRNA regulation. Six exons and five introns were identified from bacterial artificial chromosome (BAC) and expressed sequence tag (EST) sequencing, and this genomic organization is similar to mammalian and fish TLR3 genes. The putative 913 amino acid protein has a Toll/interleukin (IL)-1R (TIR) domain, a transmembrane domain, and leucine-rich repeats. In healthy trout, rtTLR3 is highly expressed in the liver, pyloric ceca, intestine, spleen, and anterior and trunk kidney tissues. To investigate whether rtTLR3 is involved in antiviral immunity, transcriptional regulation in vivo was examined by quantitative real-time polymerase chain reaction (PCR) after poly inosinic:cytidylic (I:C) and infectious hematopoietic necrosis virus (IHNV) treatments. TLR3 mRNA expression peaked 1 day after poly (I:C) injection of live animals, while the peak of gene expression after live IHNV challenge was observed on day 3. In vitro stimulation of rainbow trout anterior kidney leukocytes with poly (I:C) also enhanced rtTLR3 expression. Up-regulation was specific to viral challenge as there was no significant up-regulation of rtTLR3 mRNA levels in the spleen and a modest down-regulation in the anterior kidney after bath challenge with a gram-negative bacterial trout pathogen, Yersinia ruckeri. The sequence conservation of trout TLR3 and mRNA regulation after poly (I:C) or RNA virus exposures strongly suggest a role for trout TLR3 in antiviral immunity.
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Affiliation(s)
- M F Rodriguez
- Agriculture Research Service, National Center for Cool and Cold Water Aquaculture, United States Department of Agriculture, Kearneysville, WV 25430, USA.
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811
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Zhao Z, Date T, Li Y, Kato T, Miyamoto M, Yasui K, Wakita T. Characterization of the E-138 (Glu/Lys) mutation in Japanese encephalitis virus by using a stable, full-length, infectious cDNA clone. J Gen Virol 2005; 86:2209-2220. [PMID: 16033968 DOI: 10.1099/vir.0.80638-0] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
A stable plasmid DNA, pMWJEAT, was constructed by using full-length Japanese encephalitis virus (JEV) cDNA isolated from the wild-type strain JEV AT31. Recombinant JEV was obtained by synthetic RNA transfection into Vero cells and designated rAT virus. JEV rAT exhibited similar large-plaque morphology and antigenicity to the parental AT31 strain. Mutant clone pMWJEAT-E138K, containing a single Glu-to-Lys mutation at aa 138 of the envelope (E) protein, was also constructed to analyse the mechanisms of viral attenuation arising from this mutation. Recombinant JEV rAT-E138K was also recovered and displayed a smaller-plaque morphology and lower neurovirulence and neuroinvasiveness than either AT31 virus or rAT virus. JEV rAT-E138K exhibited greater plaque formation than rAT virus in virus-cell interactions under acidic conditions. Heparin or heparinase III treatment inhibited binding to Vero cells more efficiently for JEV rAT-E138K than for rAT virus. Inhibition of virus-cell interactions by using wheatgerm agglutinin was more effective for JEV rAT than for rAT-E138K on Vero cells. About 20 % of macropinoendocytosis of JEV rAT for Vero cells was inhibited by cytochalasin D treatment, but no such inhibition occurred for rAT-E138K virus. Furthermore, JEV rAT was predominantly secreted from infected cells, whereas rAT-E138K was more likely to be retained in infected cells. This study demonstrates clearly that a single Glu-to-Lys mutation at aa 138 of the envelope protein affects multiple steps of the viral life cycle. These multiple changes may induce substantial attenuation of JEV.
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Affiliation(s)
- Zijiang Zhao
- Department of Microbiology, Tokyo Metropolitan Institute for Neuroscience, 2-6 Musashidai, Fuchu-shi, Tokyo 183-8526, Japan
| | - Tomoko Date
- Department of Microbiology, Tokyo Metropolitan Institute for Neuroscience, 2-6 Musashidai, Fuchu-shi, Tokyo 183-8526, Japan
| | - Yuhua Li
- Chengdu Institute of Biological Products, Chengdu 610063, Sichuan Province, PR China
| | - Takanobu Kato
- Department of Microbiology, Tokyo Metropolitan Institute for Neuroscience, 2-6 Musashidai, Fuchu-shi, Tokyo 183-8526, Japan
| | - Michiko Miyamoto
- Department of Microbiology, Tokyo Metropolitan Institute for Neuroscience, 2-6 Musashidai, Fuchu-shi, Tokyo 183-8526, Japan
| | - Kotaro Yasui
- Department of Microbiology, Tokyo Metropolitan Institute for Neuroscience, 2-6 Musashidai, Fuchu-shi, Tokyo 183-8526, Japan
| | - Takaji Wakita
- Department of Microbiology, Tokyo Metropolitan Institute for Neuroscience, 2-6 Musashidai, Fuchu-shi, Tokyo 183-8526, Japan
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812
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de Bouteiller O, Merck E, Hasan UA, Hubac S, Benguigui B, Trinchieri G, Bates EEM, Caux C. Recognition of double-stranded RNA by human toll-like receptor 3 and downstream receptor signaling requires multimerization and an acidic pH. J Biol Chem 2005; 280:38133-45. [PMID: 16144834 DOI: 10.1074/jbc.m507163200] [Citation(s) in RCA: 199] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Studies involving Toll-like receptor 3 (TLR3)-deficient mice suggest that this receptor binds double-stranded RNA. In the present study, we analyzed ligand/receptor interactions and receptor-proximal events leading to TLR3 activation. The mutagenesis approach showed that certain cysteine residues and glycosylation in TLR3 amino-terminal leucine-rich repeats were necessary for ligand-induced signaling. Furthermore, inactive mutants had a dominant negative effect, suggesting that the signaling module is a multimer. We constructed a chimeric molecule fusing the amino-terminal ectodomain of TLR3 to the transmembrane and carboxyl terminal domains of CD32a containing an immunoreceptor tyrosine-based motif. Expression of TLR3-CD32 in HEK293T cells and the myeloid cell line U937 resulted in surface localization of the receptor, whereas the nonrecombinant molecule was intracellularly localized. The synthetic double-stranded RNAs poly(I-C) and poly(A-U) induced calcium mobilization in a TLR3-CD32 stably transfected U937 clone but not in control cells transfected with other constructs. An anti-TLR3 antibody also induced Ca(2+) flux but only when cross-linked by a secondary anti-immunoglobulin antibody, confirming that multimerization by the ligand is a requirement for signaling. The inhibitors of lysosome maturation, bafilomycin and chloroquine, inhibited the poly(I-C)-induced biological response in immune cells, showing that TLR3 interacted with its ligand in acidic subcellular compartments. Furthermore, TLR3-CD32 activation with poly(I-C) was only observed within a narrow pH window (pH 5.7-6.7), whereas anti-TLR3-mediated Ca(2+) flux was pH-insensitive. The importance of an acidic pH for TLR3-ligand interaction becomes critical when using oligomeric poly(I-C) (15-40-mers). These observations demonstrate that engagement of TLR3 by poly(I-C) at an acidic pH, probably in early phagolysosomes or endosomes, induces receptor aggregation leading to signaling.
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MESH Headings
- Amino Acid Sequence
- Antigens, CD/chemistry
- Antirheumatic Agents/pharmacology
- Base Sequence
- Binding Sites
- Blotting, Western
- Calcium/metabolism
- Cell Line
- Cell Membrane/metabolism
- Cell Separation
- Chloroquine/chemistry
- Cross-Linking Reagents/pharmacology
- Cysteine/chemistry
- Cysteine/metabolism
- Cytokines/metabolism
- DNA/metabolism
- Dendritic Cells/metabolism
- Dimerization
- Dose-Response Relationship, Drug
- Endosomes/metabolism
- Enzyme Inhibitors/pharmacology
- Flow Cytometry
- Genes, Dominant
- Genes, Reporter
- Glycosylation
- Humans
- Hydrogen-Ion Concentration
- Leucine/chemistry
- Leukocytes, Mononuclear/metabolism
- Ligands
- Luciferases/metabolism
- Lysosomes/chemistry
- Lysosomes/metabolism
- Macrolides/pharmacology
- Molecular Sequence Data
- Mutagenesis, Site-Directed
- Mutation
- NF-kappa B/metabolism
- Phagosomes/chemistry
- Protein Binding
- Protein Structure, Tertiary
- Receptors, IgG/biosynthesis
- Receptors, IgG/chemistry
- Recombinant Fusion Proteins/chemistry
- Recombinant Fusion Proteins/metabolism
- Sequence Homology, Amino Acid
- Signal Transduction
- Time Factors
- Toll-Like Receptor 3/chemistry
- Toll-Like Receptor 3/metabolism
- Transfection
- Tyrosine/chemistry
- U937 Cells
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Affiliation(s)
- Odette de Bouteiller
- Laboratory for Immunological Research, Schering-Plough Research Institute, 27 Chemin des Peupliers, 69571 Dardilly Cedex, France
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813
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Schröder M, Bowie AG. TLR3 in antiviral immunity: key player or bystander? Trends Immunol 2005; 26:462-8. [PMID: 16027039 DOI: 10.1016/j.it.2005.07.002] [Citation(s) in RCA: 176] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2005] [Revised: 06/15/2005] [Accepted: 07/06/2005] [Indexed: 01/12/2023]
Abstract
Toll-like receptor 3 (TLR3), which recognizes double-stranded (ds)RNA, was the first identified antiviral TLR and, because dsRNA is a universal viral molecular pattern, TLR3 has been assumed to have a central role in the host response to viruses. However, this role has recently been questioned by in vivo studies and the discovery of several other antiviral pattern-recognition receptors. In this review, the function of TLR3 in the context of these other receptors, namely TLR7, 8 and 9 and the newly identified dsRNA-receptor retinoic-acid inducible gene-I (RIG-I) is discussed. Also, recent research concerning the expression profile of TLR3, its evasion by viruses and a potential role in crosspriming is addressed, which reveals a clearer appreciation of the contribution of TLR3 to antiviral immunity.
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Affiliation(s)
- Martina Schröder
- Viral Immune Evasion Group, Department of Biochemistry, Trinity College Dublin, College Green, Dublin 2, Ireland
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814
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Navarro-Sánchez E, Desprès P, Cedillo-Barrón L. Innate immune responses to dengue virus. Arch Med Res 2005; 36:425-35. [PMID: 16099317 DOI: 10.1016/j.arcmed.2005.04.007] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2005] [Accepted: 04/29/2005] [Indexed: 01/12/2023]
Abstract
Dengue fever/dengue hemorrhagic fever (DF/DHF) has emerged as the most important mosquito-borne viral diseases in tropical areas. The dengue virus (DV) has become endemic in most tropical urban centers throughout the world, and DHF has appeared concomitantly with this expansion. Given the fact that intensity of DV replication during the early times of infection could determine clinical outcomes, which ranges from febrile illness (DF) to life-threatening disease (DHF), it is important to understand the impact of DV infection on innate immunity. Interstitial dendritic cells (DCs) are believed to constitute the first line of the innate host defense against invading DV at the anatomical sites where it replicates after the initial bite by infected mosquito. Early activation of natural killer (NK) cells and type-I interferon-dependent immunity may be also important in limiting viral replication at the early times of dengue infection. The ability of infecting DV to counter the innate antiviral immunity might account for differences in virulence observed between viral strains.
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Affiliation(s)
- Erika Navarro-Sánchez
- Unité des Interactions Moléculaires Flavivirus-Hôtes, Institut Pasteur, Paris, France
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815
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Anders HJ, Zecher D, Pawar RD, Patole PS. Molecular mechanisms of autoimmunity triggered by microbial infection. Arthritis Res Ther 2005; 7:215-24. [PMID: 16207351 PMCID: PMC1257453 DOI: 10.1186/ar1818] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Autoimmunity can be triggered by microbial infection. In this context, the discovery of Toll-like receptors (TLRs) provides new insights and research perspectives. TLRs induce innate and adaptive antimicrobial immune responses upon exposure to common pathogen-associated molecules, including lipopeptides, lipopolysaccharides, and nucleic acids. They also have the potential, however, to trigger autoimmune disease, as has been revealed by an increasing number of experimental reports. This review summarizes important facts about TLR biology, available data on their role in autoimmunity, and potential consequences for the management of patients with autoimmune disease.
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816
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Scholle F, Mason PW. West Nile virus replication interferes with both poly(I:C)-induced interferon gene transcription and response to interferon treatment. Virology 2005; 342:77-87. [PMID: 16111732 DOI: 10.1016/j.virol.2005.07.021] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2005] [Revised: 06/06/2005] [Accepted: 07/16/2005] [Indexed: 10/25/2022]
Abstract
West Nile virus (WNV), the leading cause of viral encephalitis in the United States, is an arthropod-transmitted member of the family Flaviviridae. We have explored the interaction of this positive-strand RNA virus with signaling pathways involved in induction of the host's innate immune response. Phosphorylation of STAT-1 in response to interferon (IFN) treatment and the ability of IFN to establish an antiviral state were reduced in WNV replicon-bearing cell lines. Similarly, the activation of IRF3 and stimulation of IFN-beta transcription in response to the double-stranded RNA (dsRNA) mimetic poly(I:C) were inhibited in replicon-bearing and WNV-infected HeLa cells. In contrast, WNV replicons did not affect IRF3 activation by Sendai virus infection, suggesting that not all IRF3 activating pathways are inhibited by WNV. Taken together, these findings demonstrate that WNV replication in cultured cells interferes with both the response to IFN and synthesis of IFN-beta in response to dsRNA.
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Affiliation(s)
- Frank Scholle
- Department of Pathology, 3.206B Mary Moody Northen Pavilion, University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77555-0436, USA
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817
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Kawai T, Akira S. Pathogen recognition with Toll-like receptors. Curr Opin Immunol 2005; 17:338-44. [PMID: 15950447 DOI: 10.1016/j.coi.2005.02.007] [Citation(s) in RCA: 418] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2005] [Accepted: 02/27/2005] [Indexed: 10/25/2022]
Abstract
The innate immune system is an evolutionarily conserved system of defense against microbial infections. The family of Toll-like receptors is a major class of receptors that sense molecular patterns associated with a broad range of pathogens including bacteria, viruses, fungi and protozoa. Following pathogen recognition, Toll-like receptors initiate intracellular signal transduction that results in the expression of genes involved in inflammation, antiviral responses and maturation of dendritic cells. Individual Toll-like receptors activate common and unique transcription factors through different signaling pathways to drive specific biological responses against microorganisms.
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Affiliation(s)
- Taro Kawai
- Exploratory Research for Advanced Technology (ERATO), Japan Science and Technology Agency, 3-1 Yamada-oka, Suita, Osaka 565-0871, Japan
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818
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Karikó K, Buckstein M, Ni H, Weissman D. Suppression of RNA recognition by Toll-like receptors: the impact of nucleoside modification and the evolutionary origin of RNA. Immunity 2005; 23:165-75. [PMID: 16111635 DOI: 10.1016/j.immuni.2005.06.008] [Citation(s) in RCA: 1490] [Impact Index Per Article: 78.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2005] [Revised: 05/26/2005] [Accepted: 06/15/2005] [Indexed: 10/25/2022]
Abstract
DNA and RNA stimulate the mammalian innate immune system through activation of Toll-like receptors (TLRs). DNA containing methylated CpG motifs, however, is not stimulatory. Selected nucleosides in naturally occurring RNA are also methylated or otherwise modified, but the immunomodulatory effects of these alterations remain untested. We show that RNA signals through human TLR3, TLR7, and TLR8, but incorporation of modified nucleosides m5C, m6A, m5U, s2U, or pseudouridine ablates activity. Dendritic cells (DCs) exposed to such modified RNA express significantly less cytokines and activation markers than those treated with unmodified RNA. DCs and TLR-expressing cells are potently activated by bacterial and mitochondrial RNA, but not by mammalian total RNA, which is abundant in modified nucleosides. We conclude that nucleoside modifications suppress the potential of RNA to activate DCs. The innate immune system may therefore detect RNA lacking nucleoside modification as a means of selectively responding to bacteria or necrotic tissue.
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Affiliation(s)
- Katalin Karikó
- Department of Neurosurgery, University of Pennsylvania School of Medicine, Philadelphia, 19104, USA.
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819
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Liew FY, Xu D, Brint EK, O'Neill LAJ. Negative regulation of toll-like receptor-mediated immune responses. Nat Rev Immunol 2005; 5:446-58. [PMID: 15928677 DOI: 10.1038/nri1630] [Citation(s) in RCA: 1154] [Impact Index Per Article: 60.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Toll-like receptors (TLRs) are involved in host defence against invading pathogens, functioning as primary sensors of microbial products and activating signalling pathways that induce the expression of immune and pro-inflammatory genes. However, TLRs have also been implicated in several immune-mediated and inflammatory diseases. As the immune system needs to constantly strike a balance between activation and inhibition to avoid detrimental and inappropriate inflammatory responses, TLR signalling must be tightly regulated. Here, we discuss the various negative regulatory mechanisms that have evolved to attenuate TLR signalling to maintain this immunological balance.
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Affiliation(s)
- Foo Y Liew
- Division of Immunology, Infection and Inflammation, University of Glasgow, Glasgow G11 6NT, UK.
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820
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Abstract
Toll-like receptors (TLRs) constitute an archetypal pattern recognition system. Their sophisticated biology underpins the ability of innate immunity to discriminate between highly diverse microbial pathogens and self. However, the remarkable progress made in describing this biology has also revealed new immunological systems and processes previously hidden to investigators. In particular, TLRs appear to have a fundamental role in the generation of clonal adaptive immune responses, non-infectious disease pathogenesis and even in the maintenance of normal mammalian homeostasis. Although an understanding of TLRs has answered some fundamental questions at the host-pathogen interface, further issues, particularly regarding therapeutic modulation of these receptors, have yet to be resolved.
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Affiliation(s)
- P A Hopkins
- Gram-Positive Molecular Pathogenesis Group, Department of Infectious Diseases, Division of Investigative Science, Faculty of Medicine, Imperial College, London, UK.
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821
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Vijay-Kumar M, Gentsch JR, Kaiser WJ, Borregaard N, Offermann MK, Neish AS, Gewirtz AT. Protein kinase R mediates intestinal epithelial gene remodeling in response to double-stranded RNA and live rotavirus. THE JOURNAL OF IMMUNOLOGY 2005; 174:6322-31. [PMID: 15879132 DOI: 10.4049/jimmunol.174.10.6322] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
As sentinels of host defense, intestinal epithelial cells respond to the viral pathogen rotavirus by activating a gene expression that promotes immune cell recruitment and activation. We hypothesized that epithelial sensing of rotavirus might target dsRNA, which can be detected by TLR3 or protein kinase R (PKR). Accordingly, we observed that synthetic dsRNA, polyinosinic acid:cytidylic acid (poly(I:C)), potently induced gene remodeling in model intestinal epithelia with the specific pattern of expressed genes, including both classic proinflammatory genes (e.g., IL-8), as well as genes that are classically activated in virus-infected cells (e.g., IFN-responsive genes). Poly(I:C)-induced IL-8 was concentration dependent (2-100 mug/ml) and displayed slower kinetics compared with IL-8 induced by bacterial flagellin (ET(50) approximately 24 vs 8 h poly(I:C) vs flagellin, respectively). Although model epithelia expressed detectable TLR3 mRNA, neither TLR3-neutralizing Abs nor chloroquine, which blocks activation of intracellular TLR3, attenuated epithelial responses to poly(I:C). Conversely, poly(I:C)-induced phosphorylation of PKR and inhibitors of PKR, 2-aminopurine and adenine, ablated poly(I:C)-induced gene expression but had no effect on gene expression induced by flagellin, thus suggesting that intestinal epithelial cell detection of dsRNA relies on PKR. Consistent with poly(I:C) detection by an intracellular molecule such as PKR, we observed that both uptake of and responses to poly(I:C) were polarized to the basolateral side. Lastly, we observed that the pattern of pharmacologic inhibition of responses to poly(I:C) was identical to that seen in response to infection by live rotavirus, indicating a potentially important role for PKR in activating intestinal epithelial gene expression in rotavirus infection.
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Affiliation(s)
- Matam Vijay-Kumar
- Department of Pathology and Laboratory Medicine, Epithelial Pathobiology Unit, Emory University School of Medicine, Atlanta, GA 30322, USA
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822
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Perry AK, Chen G, Zheng D, Tang H, Cheng G. The host type I interferon response to viral and bacterial infections. Cell Res 2005; 15:407-22. [PMID: 15987599 DOI: 10.1038/sj.cr.7290309] [Citation(s) in RCA: 264] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Type I interferons (IFN) are well studied cytokines with anti-viral and immune-modulating functions. Type I IFNs are produced following viral infections, but until recently, the mechanisms of viral recognition leading to IFN production were largely unknown. Toll like receptors (TLRs) have emerged as key transducers of type I IFN during viral infections by recognizing various viral components. Furthermore, much progress has been made in defining the signaling pathways downstream of TLRs for type I IFN production. TLR7 and TLR9 have become apparent as universally important in inducing type I IFN during infection with most viruses, particularly by plasmacytoid dendritic cells. New intracellular viral pattern recognition receptors leading to type I IFN production have been identified. Many bacteria can also induce the up-regulation of these cytokines. Interestingly, recent studies have found a detrimental effect on host cells if type I IFN is produced during infection with the intracellular gram-positive bacterial pathogen, Listeria monocytogenes. This review will discuss the recent advances made in defining the signaling pathways leading to type I IFN production.
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Affiliation(s)
- Andrea K Perry
- Department of Microbiology, Immunology and Molecular Genetics, University of California Los Angeles, Los Angeles, CA 90095, USA
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823
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Mehlhop E, Whitby K, Oliphant T, Marri A, Engle M, Diamond MS. Complement activation is required for induction of a protective antibody response against West Nile virus infection. J Virol 2005; 79:7466-77. [PMID: 15919902 PMCID: PMC1143684 DOI: 10.1128/jvi.79.12.7466-7477.2005] [Citation(s) in RCA: 133] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2004] [Accepted: 02/15/2005] [Indexed: 01/21/2023] Open
Abstract
Infection with West Nile virus (WNV) causes a severe infection of the central nervous system (CNS) with higher levels of morbidity and mortality in the elderly and the immunocompromised. Experiments with mice have begun to define how the innate and adaptive immune responses function to limit infection. Here, we demonstrate that the complement system, a major component of innate immunity, controls WNV infection in vitro primarily in an antibody-dependent manner by neutralizing virus particles in solution and lysing WNV-infected cells. More decisively, mice that genetically lack the third component of complement or complement receptor 1 (CR1) and CR2 developed increased CNS virus burdens and were vulnerable to lethal infection at a low dose of WNV. Both C3-deficient and CR1- and CR2-deficient mice also had significant deficits in their humoral responses after infection with markedly reduced levels of specific anti-WNV immunoglobulin M (IgM) and IgG. Overall, these results suggest that complement controls WNV infection, in part through its ability to induce a protective antibody response.
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Affiliation(s)
- Erin Mehlhop
- Department of Medicine, Molecular Microbiology, and Pathology & Immunology, Washington University School of Medicine, 660 South Euclid Ave., Box 8051, St. Louis, MO 63110, USA
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824
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825
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Cheeran MCJ, Hu S, Sheng WS, Rashid A, Peterson PK, Lokensgard JR. Differential responses of human brain cells to West Nile virus infection. J Neurovirol 2005; 11:512-24. [PMID: 16338745 DOI: 10.1080/13550280500384982] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
In recent years, West Nile virus (WNV) has emerged as a major cause of encephalitis in the United States. However, the neuropathogenesis of this flavivirus is poorly understood. In the present study, the authors used primary human brain cell cultures to investigate two neuropathogenic features: viral replication and induction of cytokines. Although neurons and astrocytes were found to support productive WNV infection, viral growth was poorly permissive in microglial cells. Compared to neuronal cultures that sustained viral growth for at least 2 weeks, replication peaked in astrocytes by 72 h post infection. In response to viral infection, astrocytes produced chemokines (CXCL10 and CCL5), but none of the cytokines (tumor necrosis factor [TNF]-alpha, interleukin [IL]-1beta, IL-6, interferon alpha or gamma) tested could be detected. Although microglial cells failed to support viral replication, WNV induced production of the proinflammatory cytokines IL-6 and TNF-alpha. Microglial cells also released robust amounts of the chemokines CXCL10 and CCL2, as well as lower levels of CCL5, in response to WNV infection. WNV-induced chemokine and cytokine production by microglia was coupled with activation of mitogen-activated protein kinase (MAPK) intracellular signaling pathways. Inhibition of p38 MAPK decreased chemokine production in response to WNV. Taken together, these findings suggest that microglial cell responses may influence the neuropathogenesis of WNV infection.
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Affiliation(s)
- Maxim C-J Cheeran
- Neuroimmunology Laboratory, Minneapolis Medical Research Foundation, University of Minnesota Medical School, 55455, USA.
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826
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Molloy S. West Nile virus makes an entrance. Nat Rev Immunol 2005. [DOI: 10.1038/nri1546] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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827
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