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Rex V, Zargari R, Stempel M, Halle S, Brinkmann MM. The innate and T-cell mediated immune response during acute and chronic gammaherpesvirus infection. Front Cell Infect Microbiol 2023; 13:1146381. [PMID: 37065193 PMCID: PMC10102517 DOI: 10.3389/fcimb.2023.1146381] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Accepted: 03/20/2023] [Indexed: 04/03/2023] Open
Abstract
Immediately after entry into host cells, viruses are sensed by the innate immune system, leading to the activation of innate antiviral effector mechanisms including the type I interferon (IFN) response and natural killer (NK) cells. This innate immune response helps to shape an effective adaptive T cell immune response mediated by cytotoxic T cells and CD4+ T helper cells and is also critical for the maintenance of protective T cells during chronic infection. The human gammaherpesvirus Epstein-Barr virus (EBV) is a highly prevalent lymphotropic oncovirus that establishes chronic lifelong infections in the vast majority of the adult population. Although acute EBV infection is controlled in an immunocompetent host, chronic EBV infection can lead to severe complications in immunosuppressed patients. Given that EBV is strictly host-specific, its murine homolog murid herpesvirus 4 or MHV68 is a widely used model to obtain in vivo insights into the interaction between gammaherpesviruses and their host. Despite the fact that EBV and MHV68 have developed strategies to evade the innate and adaptive immune response, innate antiviral effector mechanisms still play a vital role in not only controlling the acute infection but also shaping an efficient long-lasting adaptive immune response. Here, we summarize the current knowledge about the innate immune response mediated by the type I IFN system and NK cells, and the adaptive T cell-mediated response during EBV and MHV68 infection. Investigating the fine-tuned interplay between the innate immune and T cell response will provide valuable insights which may be exploited to design better therapeutic strategies to vanquish chronic herpesviral infection.
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Affiliation(s)
- Viktoria Rex
- Institute of Genetics, Technische Universität Braunschweig, Braunschweig, Germany
| | - Razieh Zargari
- Institute of Immunology, Hannover Medical School, Hannover, Germany
| | - Markus Stempel
- Institute of Genetics, Technische Universität Braunschweig, Braunschweig, Germany
- Virology and Innate Immunity Research Group, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Stephan Halle
- Institute of Immunology, Hannover Medical School, Hannover, Germany
- Institute of Clinical Chemistry, Hannover Medical School, Hannover, Germany
- *Correspondence: Stephan Halle, ; Melanie M. Brinkmann,
| | - Melanie M. Brinkmann
- Institute of Genetics, Technische Universität Braunschweig, Braunschweig, Germany
- Virology and Innate Immunity Research Group, Helmholtz Centre for Infection Research, Braunschweig, Germany
- *Correspondence: Stephan Halle, ; Melanie M. Brinkmann,
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2
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Gaglia MM. Anti-viral and pro-inflammatory functions of Toll-like receptors during gamma-herpesvirus infections. Virol J 2021; 18:218. [PMID: 34749760 PMCID: PMC8576898 DOI: 10.1186/s12985-021-01678-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Accepted: 10/12/2021] [Indexed: 12/15/2022] Open
Abstract
Toll-like receptors (TLRs) control anti-viral responses both directly in infected cells and in responding cells of the immune systems. Therefore, they are crucial for responses against the oncogenic γ-herpesviruses Epstein-Barr virus and Kaposi's sarcoma-associated herpesvirus and the related murine virus MHV68, which directly infect immune system cells. However, since these viruses also cause lifelong persistent infections, TLRs may also be involved in modulation of inflammation during latent infection and contribute to virus-driven tumorigenesis. This review summarizes work on both of these aspects of TLR/γ-herpesvirus interactions, as well as results showing that TLR activity can drive these viruses' re-entry into the replicative lytic cycle.
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Affiliation(s)
- Marta Maria Gaglia
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, 02111, USA.
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3
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Activation and Evasion of Innate Immunity by Gammaherpesviruses. J Mol Biol 2021; 434:167214. [PMID: 34437888 PMCID: PMC8863980 DOI: 10.1016/j.jmb.2021.167214] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2021] [Revised: 08/11/2021] [Accepted: 08/13/2021] [Indexed: 12/20/2022]
Abstract
Gammaherpesviruses are ubiquitous pathogens that establish lifelong infections in the vast majority of adults worldwide. Importantly, these viruses are associated with numerous malignancies and are responsible for significant human cancer burden. These virus-associated cancers are due, in part, to the ability of gammaherpesviruses to successfully evade the innate immune response throughout the course of infection. In this review, we will summarize the current understanding of how gammaherpesviruses are detected by innate immune sensors, how these viruses evade recognition by host cells, and how this knowledge can inform novel therapeutic approaches for these viruses and their associated diseases.
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4
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Jondle CN, Tarakanova VL. Innate immunity and alpha/gammaherpesviruses: first impressions last a lifetime. Curr Opin Virol 2020; 44:81-89. [PMID: 32777757 DOI: 10.1016/j.coviro.2020.07.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Revised: 06/25/2020] [Accepted: 07/04/2020] [Indexed: 12/26/2022]
Abstract
Innate immune system is considered the first line of defense during viral invasion, with the wealth of the literature demonstrating innate immune control of diverse viruses during acute infection. What is far less clear is the role of innate immune system during chronic virus infections. This short review focuses on alphaherpesviruses and gammaherpesviruses, two highly prevalent herpesvirus subfamilies that, following a brief, once in a lifetime period of acute lytic infection, establish life-long latent infection that is characterized by sporadic reactivation in an immunocompetent host. In spite of many similarities, these two viral families are characterized by distinct cellular tropism and pathogenesis. Here we focus on the published in vivo studies to review known interactions of these two viral subfamilies with the innate immunity of the intact host, both during acute and, particularly, chronic virus infection.
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Affiliation(s)
- Christopher N Jondle
- Department of Microbiology and Immunology, Medical College of Wisconsin, 8701 W Watertown Plank Road, Milwaukee, WI, 53226, United States
| | - Vera L Tarakanova
- Department of Microbiology and Immunology, Medical College of Wisconsin, 8701 W Watertown Plank Road, Milwaukee, WI, 53226, United States; Cancer Center, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI, 53226, United States.
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5
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Conserved Herpesvirus Kinase ORF36 Activates B2 Retrotransposons during Murine Gammaherpesvirus Infection. J Virol 2020; 94:JVI.00262-20. [PMID: 32404524 DOI: 10.1128/jvi.00262-20] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2020] [Accepted: 05/04/2020] [Indexed: 12/14/2022] Open
Abstract
Short interspersed nuclear elements (SINEs) are RNA polymerase III (RNAPIII)-transcribed, retrotransposable noncoding RNA (ncRNA) elements ubiquitously spread throughout mammalian genomes. While normally silenced in healthy somatic tissue, SINEs can be induced during infection with DNA viruses, including the model murine gammaherpesvirus 68 (MHV68). Here, we explored the mechanisms underlying MHV68 activation of SINE ncRNAs. We demonstrate that lytic MHV68 infection of B cells, macrophages, and fibroblasts leads to robust activation of the B2 family of SINEs in a cell-autonomous manner. B2 ncRNA induction requires neither host innate immune signaling factors nor involvement of the RNAPIII master regulator Maf1. However, we identified MHV68 ORF36, the conserved herpesviral kinase, as playing a key role in B2 induction during lytic infection. SINE activation is linked to ORF36 kinase activity and can also be induced by inhibition of histone deacetylases 1 and 2 (HCAC 1/2), which is one of the known ORF36 functions. Collectively, our data suggest that ORF36-mediated changes in chromatin modification contribute to B2 activation during MHV68 infection and that this activity is conserved in other herpesviral protein kinase homologs.IMPORTANCE Viral infection dramatically changes the levels of many types of RNA in a cell. In particular, certain oncogenic viruses activate expression of repetitive genes called retrotransposons, which are normally silenced due to their ability to copy and spread throughout the genome. Here, we established that infection with the gammaherpesvirus MHV68 leads to a dramatic induction of a class of noncoding retrotransposons called B2 SINEs in multiple cell types. We then explored how MHV68 activates B2 SINEs, revealing a role for the conserved herpesviral protein kinase ORF36. Both ORF36 kinase-dependent and kinase-independent functions contribute to B2 induction, perhaps through ORF36 targeting of proteins involved in controlling the accessibility of chromatin surrounding SINE loci. Understanding the features underlying induction of these elements following MHV68 infection should provide insight into core elements of SINE regulation, as well as disregulation of SINE elements associated with disease.
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Carriere J, Rao Y, Liu Q, Lin X, Zhao J, Feng P. Post-translational Control of Innate Immune Signaling Pathways by Herpesviruses. Front Microbiol 2019; 10:2647. [PMID: 31798565 PMCID: PMC6868034 DOI: 10.3389/fmicb.2019.02647] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Accepted: 10/30/2019] [Indexed: 12/21/2022] Open
Abstract
Herpesviruses constitute a large family of disease-causing DNA viruses. Each herpesvirus strain is capable of infecting particular organisms with a specific cell tropism. Upon infection, pattern recognition receptors (PRRs) recognize conserved viral features to trigger signaling cascades that culminate in the production of interferons and pro-inflammatory cytokines. To invoke a proper immune response while avoiding collateral tissue damage, signaling proteins involved in these cascades are tightly regulated by post-translational modifications (PTMs). Herpesviruses have developed strategies to subvert innate immune signaling pathways in order to ensure efficient viral replication and achieve persistent infection. The ability of these viruses to control the proteins involved in these signaling cascades post-translationally, either directly via virus-encoded enzymes or indirectly through the deregulation of cellular enzymes, has been widely reported. This ability provides herpesviruses with a powerful tool to shut off or restrict host antiviral and inflammatory responses. In this review, we highlight recent findings on the herpesvirus-mediated post-translational control along PRR-mediated signaling pathways.
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Affiliation(s)
| | | | | | | | | | - Pinghui Feng
- Section of Infection and Immunity, Ostrow School of Dentistry, University of Southern California, Los Angeles, CA, United States
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Wilke CA, Chadwick MM, Chan PR, Moore BB, Zhou X. Stem cell transplantation impairs dendritic cell trafficking and herpesvirus immunity. JCI Insight 2019; 4:130210. [PMID: 31479426 PMCID: PMC6795288 DOI: 10.1172/jci.insight.130210] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Accepted: 08/21/2019] [Indexed: 12/25/2022] Open
Abstract
Long-term survivors after hematopoietic stem cell transplantation are at high risk of infection, which accounts for one-third of all deaths related to stem cell transplantation. Little is known about the cause of inferior host defense after immune cell reconstitution. Here, we exploited a murine syngeneic BM transplantation (BMT) model of late infection with murine gammaherpesvirus 68 (MHV-68) to determine the role of conventional DC (cDC) trafficking in adaptive immunity in BMT mice. After infection, the expression of chemokine Ccl21 in the lung is reduced and the migration of cDCs into lung draining lymph nodes (dLNs) is impaired in BMT mice, limiting the opportunity for cDCs to prime Th cells in the dLNs. While cDC subsets are redundant in priming Th1 cells, Notch2 functions in cDC2s are required for priming increased Th17 responses in BMT mice, and cDC1s can lessen this activity. Importantly, Th17 cells can be primed both in the lungs and dLNs, allowing for increased Th17 responses without optimum cDC trafficking in BMT mice. Taken together, impaired cDC trafficking in BMT mice reduces protective Th1 responses and allows increased pathogenic Th17 responses. Thus, we have revealed a previously unknown mechanism for BMT procedures to cause long-term inferior immune responses to herpes viral infection.
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Affiliation(s)
- Carol A. Wilke
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Mathew M. Chadwick
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Paul R. Chan
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Bethany B. Moore
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Michigan, USA
- Department of Microbiology and Immunology, University of Michigan, Ann Arbor, Michigan, USA
| | - Xiaofeng Zhou
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Michigan, USA
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8
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Endosomal Toll-Like Receptors 7 and 9 Cooperate in Detection of Murine Gammaherpesvirus 68 Infection. J Virol 2019; 93:JVI.01173-18. [PMID: 30429335 DOI: 10.1128/jvi.01173-18] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2018] [Accepted: 11/02/2018] [Indexed: 12/13/2022] Open
Abstract
Murine gammaherpesvirus 68 (MHV68) is a small-animal model suitable for study of the human pathogens Epstein-Barr virus and Kaposi's sarcoma-associated herpesvirus. Here, we have characterized the roles of the endosomal Toll-like receptor (TLR) escort protein UNC93B, endosomal TLR7, -9, and -13, and cell surface TLR2 in MHV68 detection. We found that the alpha interferon (IFN-α) response of plasmacytoid dendritic cells (pDC) to MHV68 was reduced in Tlr9 -/- cells compared to levels in wild type (WT) cells but not completely lost. Tlr7 -/- pDC responded similarly to WT. However, we found that in Unc93b -/- pDC, as well as in Tlr7 -/- Tlr9 -/- double-knockout pDC, the IFN-α response to MHV68 was completely abolished. Thus, the only pattern recognition receptors contributing to the IFN-α response to MHV68 in pDC are TLR7 and TLR9, but the contribution of TLR7 is masked by the presence of TLR9. To address the role of UNC93B and TLR for MHV68 infection in vivo, we infected mice with MHV68. Lytic replication of MHV68 after intravenous infection was enhanced in the lungs, spleen, and liver of UNC93B-deficient mice, in the spleen of TLR9-deficient mice, and in the liver and spleen of Tlr7 -/- Tlr9 -/- mice. The absence of TLR2 or TLR13 did not affect lytic viral titers. We then compared reactivation of MHV68 from latently infected WT, Unc93b -/-, Tlr7 -/- Tlr9 -/-, Tlr7 -/-, and Tlr9 -/- splenocytes. We observed enhanced reactivation and latent viral loads, particularly from Tlr7 -/- Tlr9 -/- splenocytes compared to levels in the WT. Our data show that UNC93B-dependent TLR7 and TLR9 cooperate in and contribute to detection and control of MHV68 infection.IMPORTANCE The two human gammaherpesviruses, Epstein-Barr virus (EBV) and Kaposi's sarcoma-associated herpesvirus (KSHV), can cause aggressive forms of cancer. These herpesviruses are strictly host specific, and therefore the homolog murine gammaherpesvirus 68 (MHV68) is a widely used model to obtain in vivo insights into the interaction between these two gammaherpesviruses and their host. Like EBV and KSHV, MHV68 establishes lifelong latency in B cells. The innate immune system serves as one of the first lines of host defense, with pattern recognition receptors such as the Toll-like receptors playing a crucial role in mounting a potent antiviral immune response to various pathogens. Here, we shed light on a yet unanticipated role of Toll-like receptor 7 in the recognition of MHV68 in a subset of immune cells called plasmacytoid dendritic cells, as well as on the control of this virus in its host.
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9
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Shen Y, Wang S, Sun F, Zheng G, Wu T, Du Y, Zhang S, Qian J, Sun R. Inhibition of murine herpesvirus-68 replication by IFN-gamma in macrophages is counteracted by the induction of SOCS1 expression. PLoS Pathog 2018; 14:e1007202. [PMID: 30075008 PMCID: PMC6093694 DOI: 10.1371/journal.ppat.1007202] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Revised: 08/15/2018] [Accepted: 07/08/2018] [Indexed: 01/20/2023] Open
Abstract
Gamma interferon (IFN-γ) is known to negatively regulate murine gammaherpesvirus-68 (MHV-68 or γHV-68) replication. This process involves the suppression of the viral gene replication and transcription activator (RTA) promoter, as well as activation of signal transducers and activators of transcription (STAT1). Notably, this effect is gradually attenuated during MHV-68 infection of bone marrow-derived macrophages (BMMs), which raised the possibility that the virus may utilize a mechanism that counteracts the antiviral effect of IFN-γ. By identifying the cellular factors that negatively regulate JAK-STAT1 signaling, we revealed that the infection of BMMs by MHV-68 induces the expression of suppressor of cytokine signaling 1 (SOCS1) and that depletion of SOCS1 restores the inhibitory effect of IFN-γ on virus replication. Moreover, we demonstrated that the expression of SOCS1 was induced as a result of the Toll-like receptor 3 (TLR3) mediated activation of the NF-κB signaling cascade. In conclusion, we report that TLR3-TRAF-NF-κB signaling pathway play a role in the induction of SOCS1 that counteracts the antiviral effect of IFN-γ during MHV-68 infection. This process is cell type-specific: it is functional in macrophages, but not in epithelial cells or fibroblasts. Our study reveals a mechanism that balances the immune responses and the escape of a gamma-herpesvirus in some antigen-presenting cells. While viruses have developed various mechanisms to evade immune responses, hosts also have mechanisms to negatively regulate the antiviral signaling pathways to minimize potential damage. In this study, we show that MHV-68, a gamma-herpesvirus, is able to stimulate macrophages to produce the cellular protein SOCS1, which reduces the antiviral effect initiated by IFN-γ, in a cell type specific manner. These findings provide one more example to support the concept that viruses utilize SOCS1 as an immune evasion mechanism. We also show that TLR3-NF-κB signaling is responsible for the induced production of SOCS1. Our finding that TLR3/NF-κB/SOCS1 impedes the action of IFN-γ/STAT1 on RTA might offer a reasonable explanation of how virus-host interaction achieves a balance to facilitate intra-host spreading and transmission.
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Affiliation(s)
- Yong Shen
- Cancer Institute (Key Laboratory of Cancer Prevention and Intervention, China National Ministry of Education, Key Laboratory of Molecular Biology in Medical Sciences, Zhejiang Province, China), The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, P. R. China
- Research Center of Infection and Immunity, ZJU-UCLA Joint Center for Medical Education and Research, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Zhejiang University School of Medicine, Hangzhou, P. R. China
| | - Saisai Wang
- Cancer Institute (Key Laboratory of Cancer Prevention and Intervention, China National Ministry of Education, Key Laboratory of Molecular Biology in Medical Sciences, Zhejiang Province, China), The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, P. R. China
- Research Center of Infection and Immunity, ZJU-UCLA Joint Center for Medical Education and Research, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Zhejiang University School of Medicine, Hangzhou, P. R. China
| | - Fangfang Sun
- Cancer Institute (Key Laboratory of Cancer Prevention and Intervention, China National Ministry of Education, Key Laboratory of Molecular Biology in Medical Sciences, Zhejiang Province, China), The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, P. R. China
- Research Center of Infection and Immunity, ZJU-UCLA Joint Center for Medical Education and Research, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Zhejiang University School of Medicine, Hangzhou, P. R. China
| | - Gang Zheng
- Department of Cardiology, the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, P. R. China
| | - Tingting Wu
- Cancer Institute (Key Laboratory of Cancer Prevention and Intervention, China National Ministry of Education, Key Laboratory of Molecular Biology in Medical Sciences, Zhejiang Province, China), The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, P. R. China
- Research Center of Infection and Immunity, ZJU-UCLA Joint Center for Medical Education and Research, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Zhejiang University School of Medicine, Hangzhou, P. R. China
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, California, United States of America
| | - Yushen Du
- Cancer Institute (Key Laboratory of Cancer Prevention and Intervention, China National Ministry of Education, Key Laboratory of Molecular Biology in Medical Sciences, Zhejiang Province, China), The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, P. R. China
- Research Center of Infection and Immunity, ZJU-UCLA Joint Center for Medical Education and Research, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Zhejiang University School of Medicine, Hangzhou, P. R. China
| | - Suzhan Zhang
- Cancer Institute (Key Laboratory of Cancer Prevention and Intervention, China National Ministry of Education, Key Laboratory of Molecular Biology in Medical Sciences, Zhejiang Province, China), The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, P. R. China
| | - Jing Qian
- Research Center of Infection and Immunity, ZJU-UCLA Joint Center for Medical Education and Research, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Zhejiang University School of Medicine, Hangzhou, P. R. China
- Pharmaceutical Informatics Institute, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, P. R. China
- * E-mail: (JQ); (RS)
| | - Ren Sun
- Cancer Institute (Key Laboratory of Cancer Prevention and Intervention, China National Ministry of Education, Key Laboratory of Molecular Biology in Medical Sciences, Zhejiang Province, China), The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, P. R. China
- Research Center of Infection and Immunity, ZJU-UCLA Joint Center for Medical Education and Research, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Zhejiang University School of Medicine, Hangzhou, P. R. China
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, California, United States of America
- * E-mail: (JQ); (RS)
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10
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Host Tumor Suppressor p18 INK4c Functions as a Potent Cell-Intrinsic Inhibitor of Murine Gammaherpesvirus 68 Reactivation and Pathogenesis. J Virol 2018; 92:JVI.01604-17. [PMID: 29298882 DOI: 10.1128/jvi.01604-17] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2017] [Accepted: 12/09/2017] [Indexed: 12/13/2022] Open
Abstract
Gammaherpesviruses are common viruses associated with lifelong infection and increased disease risk. Reactivation from latency aids the virus in maintaining infection throughout the life of the host and is responsible for a wide array of disease outcomes. Previously, we demonstrated that the virus-encoded cyclin (v-cyclin) of murine gammaherpesvirus 68 (γHV68) is essential for optimal reactivation from latency in normal mice but not in mice lacking the host tumor suppressor p18INK4c (p18). Whether p18 plays a cell-intrinsic or -extrinsic role in constraining reactivation remains unclear. Here, we generated recombinant viruses in which we replaced the viral cyclin with the cellular p18INK4c gene (p18KI) for targeted expression of p18, specifically within infected cells. We find that the p18KI virus is similar to the cyclin-deficient virus (cycKO) in lytic infection, establishment of latency, and infected cell reservoirs. While the cycKO virus is capable of reactivation in p18-deficient mice, expression of p18 from the p18KI virus results in a profound reactivation defect. These data demonstrate that p18 limits reactivation within latently infected cells, functioning in a cell-intrinsic manner. Further, the p18KI virus showed greater attenuation of virus-induced lethal pneumonia than the cycKO virus, indicating that p18 could further restrict γHV68 pathogenesis even in p18-sufficient mice. These studies demonstrate that host p18 imposes the requirement for the viral cyclin to reactivate from latency by functioning in latently infected cells and that p18 expression is associated with decreased disease, thereby identifying p18 as a compelling host target to limit chronic gammaherpesvirus pathogenesis.IMPORTANCE Gammaherpesviruses are ubiquitous viruses associated with multiple malignancies. The propensity to cycle between latency and reactivation results in an infection that is never cleared and often difficult to treat. Understanding the balance between latency and reactivation is integral to treating gammaherpesvirus infection and associated disease outcomes. This work characterizes the role of a novel inhibitor of reactivation, host p18INK4c, thereby bringing more clarity to a complex process with significant outcomes for infected individuals.
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11
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LeBel M, Egarnes B, Brunet A, Lacerte P, Paré A, Lacroix S, Brown JP, Gosselin J. Ly6C high monocytes facilitate transport of Murid herpesvirus 68 into inflamed joints of arthritic mice. Eur J Immunol 2017; 48:250-257. [PMID: 28980305 DOI: 10.1002/eji.201747048] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Revised: 09/20/2017] [Accepted: 09/29/2017] [Indexed: 01/08/2023]
Abstract
Viruses, particularly the Epstein-Barr virus (EBV) has long been suspected to exacerbate acute arthritic symptoms. However, the cell populations that contribute to import viruses into the inflamed tissues remain to be identified. In the present study, we have investigated the role of monocytes in the transport of Murid herpesvirus 68 (MHV-68), a mouse virus closely related to EBV, using the serum transfer-induced arthritis (STIA) model. We found compelling evidence that MHV-68 infection markedly increased disease severity in NR4A1-/- mice, which are deficient for Ly6Clow monocytes. In contrast, the MHV-68-induced enhancement of joint inflammation was lessened in CCR2-/- mice, suggesting the involvement of inflammatory Ly6Chigh monocytes in viral transport. We also observed that following selective depletion of monocyte subsets by administration of clodronate, MHV-68 transport into the synovium occurs only in the presence of Ly6Chigh monocytes. Tracking of adoptively transferred Ly6Chigh GFP infected monocytes into arthritic CCR2-/- mice by two-photon intravital microscopy showed that this monocyte subset has the capacity to deliver viruses to inflamed AR joints, as confirmed by the detection of viral DNA in inflamed tissues of recipient mice. We thus conclude that Ly6Chigh monocytes import MHV-68 when they are mobilized to the inflamed arthritic joint.
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Affiliation(s)
- Manon LeBel
- Laboratory of Innate Immunology, Centre de recherche du CHU de Québec - Université Laval, Québec, QC, Canada
| | - Benoit Egarnes
- Laboratory of Innate Immunology, Centre de recherche du CHU de Québec - Université Laval, Québec, QC, Canada
| | - Alexandre Brunet
- Department of Molecular Medicine, Université Laval, Québec, QC, Canada.,Centre de recherche du CHU de Québec - Université Laval, Québec, QC, Canada
| | - Patricia Lacerte
- Laboratory of Innate Immunology, Centre de recherche du CHU de Québec - Université Laval, Québec, QC, Canada
| | - Alexandre Paré
- Centre de recherche du CHU de Québec - Université Laval, Québec, QC, Canada
| | - Steve Lacroix
- Department of Molecular Medicine, Université Laval, Québec, QC, Canada.,Centre de recherche du CHU de Québec - Université Laval, Québec, QC, Canada
| | - Jacques P Brown
- Division of Rheumatology, CHU de Québec - Université Laval (CHUL), Infectious and Immune Diseases, Centre de recherche du CHU de Québec - Université Laval (CHUL), Québec, QC, Canada
| | - Jean Gosselin
- Laboratory of Innate Immunology, Centre de recherche du CHU de Québec - Université Laval, Québec, QC, Canada.,Department of Molecular Medicine, Université Laval, Québec, QC, Canada
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12
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Schock SN, Chandra NV, Sun Y, Irie T, Kitagawa Y, Gotoh B, Coscoy L, Winoto A. Induction of necroptotic cell death by viral activation of the RIG-I or STING pathway. Cell Death Differ 2017; 24:615-625. [PMID: 28060376 DOI: 10.1038/cdd.2016.153] [Citation(s) in RCA: 98] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Revised: 11/26/2016] [Accepted: 12/07/2016] [Indexed: 01/02/2023] Open
Abstract
Necroptosis is a form of necrotic cell death that requires the activity of the death domain-containing kinase RIP1 and its family member RIP3. Necroptosis occurs when RIP1 is deubiquitinated to form a complex with RIP3 in cells deficient in the death receptor adapter molecule FADD or caspase-8. Necroptosis may play a role in host defense during viral infection as viruses like vaccinia can induce necroptosis while murine cytomegalovirus encodes a viral inhibitor of necroptosis. To see how general the interplay between viruses and necroptosis is, we surveyed seven different viruses. We found that two of the viruses tested, Sendai virus (SeV) and murine gammaherpesvirus-68 (MHV68), are capable of inducing dramatic necroptosis in the fibrosarcoma L929 cell line. We show that MHV68-induced cell death occurs through the cytosolic STING sensor pathway in a TNF-dependent manner. In contrast, SeV-induced death is mostly independent of TNF. Knockdown of the RNA sensing molecule RIG-I or the RIP1 deubiquitin protein, CYLD, but not STING, rescued cells from SeV-induced necroptosis. Accompanying necroptosis, we also find that wild type but not mutant SeV lacking the viral proteins Y1 and Y2 result in the non-ubiquitinated form of RIP1. Expression of Y1 or Y2 alone can suppress RIP1 ubiquitination but CYLD is dispensable for this process. Instead, we found that Y1 and Y2 can inhibit cIAP1-mediated RIP1 ubiquitination. Interestingly, we also found that SeV infection of B6 RIP3-/- mice results in increased inflammation in the lung and elevated SeV-specific T cells. Collectively, these data identify viruses and pathways that can trigger necroptosis and highlight the dynamic interplay between pathogen-recognition receptors and cell death induction.
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Affiliation(s)
- Suruchi N Schock
- Department of Molecular and Cell Biology and Cancer Research Laboratory, 469 LSA, University of California, Berkeley, CA 94720-3200, USA
| | - Neha V Chandra
- Department of Molecular and Cell Biology and Cancer Research Laboratory, 469 LSA, University of California, Berkeley, CA 94720-3200, USA
| | - Yuefang Sun
- Department of Molecular and Cell Biology and Cancer Research Laboratory, 469 LSA, University of California, Berkeley, CA 94720-3200, USA
| | - Takashi Irie
- Department of Virology, Institute of Biomedical & Health Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8551, Japan
| | - Yoshinori Kitagawa
- Division of Microbiology and Infectious Diseases, Department of Pathology, Shiga University of Medical Science, Seta, Otsu, Shiga 520-2192, Japan
| | - Bin Gotoh
- Division of Microbiology and Infectious Diseases, Department of Pathology, Shiga University of Medical Science, Seta, Otsu, Shiga 520-2192, Japan
| | - Laurent Coscoy
- Department of Molecular and Cell Biology and Cancer Research Laboratory, 469 LSA, University of California, Berkeley, CA 94720-3200, USA
| | - Astar Winoto
- Department of Molecular and Cell Biology and Cancer Research Laboratory, 469 LSA, University of California, Berkeley, CA 94720-3200, USA
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Leifer CA, Medvedev AE. Molecular mechanisms of regulation of Toll-like receptor signaling. J Leukoc Biol 2016; 100:927-941. [PMID: 27343013 DOI: 10.1189/jlb.2mr0316-117rr] [Citation(s) in RCA: 184] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2016] [Accepted: 06/01/2016] [Indexed: 01/22/2023] Open
Abstract
TLRs play a critical role in the detection of microbes and endogenous "alarmins" to initiate host defense, yet they can also contribute to the development and progression of inflammatory and autoimmune diseases. To avoid pathogenic inflammation, TLR signaling is subject to multilayer regulatory control mechanisms, including cooperation with coreceptors, post-translational modifications, cleavage, cellular trafficking, and interactions with negative regulators. Nucleic acid-sensing TLRs are particularly interesting in this regard, as they can both recognize host-derived structures and require internalization of their ligand as a result of intracellular sequestration of the nucleic acid-sensing TLRs. This review summarizes the regulatory mechanisms of TLRs, including regulation of their access to ligands, receptor folding, intracellular trafficking, and post-translational modifications, as well as how altered control mechanism could contribute to inflammatory and autoimmune disorders.
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Affiliation(s)
- Cynthia A Leifer
- Department of Microbiology and Immunology, Cornell University, Ithaca, New York, USA; and
| | - Andrei E Medvedev
- Department of Immunology, University of Connecticut Heath Center, Farmington, Connecticut, USA
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14
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Abortively Infected Astrocytes Appear To Represent the Main Source of Interferon Beta in the Virus-Infected Brain. J Virol 2015; 90:2031-8. [PMID: 26656686 DOI: 10.1128/jvi.02979-15] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2015] [Accepted: 11/30/2015] [Indexed: 02/04/2023] Open
Abstract
UNLABELLED Interferon beta (IFN-β) is a key component of cellular innate immunity in mammals, and it constitutes the first line of defense during viral infection. Studies with cultured cells previously showed that almost all nucleated cells are able to produce IFN-β to various extents, but information about the in vivo sources of IFN-β remains incomplete. By applying immunohistochemistry and employing conditional-reporter mice that express firefly luciferase under the control of the IFN-β promoter in either all or only distinct cell types, we found that astrocytes are the main producers of IFN-β after infection of the brain with diverse neurotropic viruses, including rabies virus, Theiler's murine encephalomyelitis virus, and vesicular stomatitis virus. Analysis of a panel of knockout mouse strains revealed that sensing of viral components via both RIG-I-like helicases and Toll-like receptors contributes to IFN induction in the infected brain. A genetic approach to permanently mark rabies virus-infected cells in the brain showed that a substantial number of astrocytes became labeled and, therefore, must have been infected by the virus at least transiently. Thus, our results strongly indicate that abortive viral infection of astrocytes can trigger pattern recognition receptor signaling events which result in secretion of IFN-β that confers antiviral protection. IMPORTANCE Previous work indicated that astrocytes are the main producers of IFN after viral infection of the central nervous system (CNS), but it remained unclear how astrocytes might sense those viruses which preferentially replicate in neurons. We have now shown that virus sensing by both RIG-I-like helicases and Toll-like receptors is involved. Our results further demonstrate that astrocytes get infected in a nonproductive manner under these conditions, indicating that abortive infection of astrocytes plays a previously unappreciated role in the innate antiviral defenses of the CNS.
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15
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Karijolich J, Abernathy E, Glaunsinger BA. Infection-Induced Retrotransposon-Derived Noncoding RNAs Enhance Herpesviral Gene Expression via the NF-κB Pathway. PLoS Pathog 2015; 11:e1005260. [PMID: 26584434 PMCID: PMC4652899 DOI: 10.1371/journal.ppat.1005260] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2015] [Accepted: 10/13/2015] [Indexed: 02/07/2023] Open
Abstract
Short interspersed nuclear elements (SINEs) are highly abundant, RNA polymerase III-transcribed noncoding retrotransposons that are silenced in somatic cells but activated during certain stresses including viral infection. How these induced SINE RNAs impact the host-pathogen interaction is unknown. Here we reveal that during murine gammaherpesvirus 68 (MHV68) infection, rapidly induced SINE RNAs activate the antiviral NF-κB signaling pathway through both mitochondrial antiviral-signaling protein (MAVS)-dependent and independent mechanisms. However, SINE RNA-based signaling is hijacked by the virus to enhance viral gene expression and replication. B2 RNA expression stimulates IKKβ-dependent phosphorylation of the major viral lytic cycle transactivator protein RTA, thereby enhancing its activity and increasing progeny virion production. Collectively, these findings suggest that SINE RNAs participate in the innate pathogen response mechanism, but that herpesviruses have evolved to co-opt retrotransposon activation for viral benefit. Short interspersed nuclear elements (SINEs) are noncoding mobile genetic elements that are present at ~106 copies per mammalian genome, roughly comprising 10% of mammalian genomic real estate. SINEs are typically transcriptionally silenced, though in some cases viral infection can promote their expression, yet to an unknown functional outcome. Thus, SINE elements represent the largest class of infection-inducible noncoding RNAs that are functionally uncharacterized. Here, we reveal that SINE RNAs play a critical role in the host-pathogen interaction in that they are required for efficient murine gammaherpesvirus 68 (MHV68) replication and gene expression. We demonstrate that SINE RNAs, both exogenously expressed and infection-induced, are robust activators of the IKKβ kinase, a key signaling molecule in the innate immune response. Activation of the IKKβ kinase by SINE RNA is mediated through both MAVS-dependent and independent mechanisms. Moreover, we demonstrate the activation of the IKKβ via SINE RNA is required to drive the phosphorylation of MHV68 RTA, the main viral transcriptional activator, which enhances its transcriptional activating property. Collectively, we reveal the first example of a role for SINE RNAs in the host-pathogen interaction and identify them as a key immune signaling molecule early during infection. Though SINE RNAs activate the innate immune response, MHV68 has co-opted SINE-mediate innate immune activation to enhance the viral lifecycle.
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Affiliation(s)
- John Karijolich
- Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, California, United States of America
| | - Emma Abernathy
- Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, California, United States of America
| | - Britt A. Glaunsinger
- Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, California, United States of America
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, California, United States of America
- Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, California, United States of America
- * E-mail:
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16
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Chow J, Franz KM, Kagan JC. PRRs are watching you: Localization of innate sensing and signaling regulators. Virology 2015; 479-480:104-9. [PMID: 25800355 PMCID: PMC4424080 DOI: 10.1016/j.virol.2015.02.051] [Citation(s) in RCA: 87] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2014] [Revised: 02/24/2015] [Accepted: 02/27/2015] [Indexed: 12/24/2022]
Abstract
To prevent the spread of infection, an invading pathogen must first be recognized by the innate immune system. Host pattern recognition receptors detect distinct pathogen-associated molecules and induce the transcription and release of interferon and inflammatory molecules to resolve infection. Unlike infections with pathogens that replicate autonomously from the host, viral infections blur the boundaries of self and non-self. Differentiation of host from virus is achieved by restricting localization of host nucleic acids and by placing pattern recognition receptors in specific subcellular compartments. Within this review, we discuss how several families of pattern recognition receptors act to provide a comprehensive surveillance network that has the potential to induce interferon expression in response to any viral infection.
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Affiliation(s)
- Jonathan Chow
- Division of Gastroenterology, Boston Children׳s Hospital, Harvard Medical School, Boston, MA 02115, USA; Program in Immunology, Harvard Medical School, Boston, MA 02115, USA
| | - Kate M Franz
- Division of Gastroenterology, Boston Children׳s Hospital, Harvard Medical School, Boston, MA 02115, USA; Program in Virology, Harvard Medical School, Boston, MA 02115, USA
| | - Jonathan C Kagan
- Division of Gastroenterology, Boston Children׳s Hospital, Harvard Medical School, Boston, MA 02115, USA; Program in Immunology, Harvard Medical School, Boston, MA 02115, USA; Program in Virology, Harvard Medical School, Boston, MA 02115, USA.
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17
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Sun C, Schattgen SA, Pisitkun P, Jorgensen JP, Hilterbrand AT, Wang LJ, West JA, Hansen K, Horan KA, Jakobsen MR, O'Hare P, Adler H, Sun R, Ploegh HL, Damania B, Upton JW, Fitzgerald KA, Paludan SR. Evasion of innate cytosolic DNA sensing by a gammaherpesvirus facilitates establishment of latent infection. THE JOURNAL OF IMMUNOLOGY 2015; 194:1819-31. [PMID: 25595793 DOI: 10.4049/jimmunol.1402495] [Citation(s) in RCA: 78] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Herpesviruses are DNA viruses harboring the capacity to establish lifelong latent-recurrent infections. There is limited knowledge about viruses targeting the innate DNA-sensing pathway, as well as how the innate system impacts on the latent reservoir of herpesvirus infections. In this article, we report that murine gammaherpesvirus 68 (MHV68), in contrast to α- and β-herpesviruses, induces very limited innate immune responses through DNA-stimulated pathways, which correspondingly played only a minor role in the control of MHV68 infections in vivo. Similarly, Kaposi's sarcoma-associated herpesvirus also did not stimulate immune signaling through the DNA-sensing pathways. Interestingly, an MHV68 mutant lacking deubiquitinase (DUB) activity, embedded within the large tegument protein open reading frame (ORF)64, gained the capacity to stimulate the DNA-activated stimulator of IFN genes (STING) pathway. We found that ORF64 targeted a step in the DNA-activated pathways upstream of the bifurcation into the STING and absent in melanoma 2 pathways, and lack of the ORF64 DUB was associated with impaired delivery of viral DNA to the nucleus, which, instead, localized to the cytoplasm. Correspondingly, the ORF64 DUB active site mutant virus exhibited impaired ability to establish latent infection in wild-type, but not STING-deficient, mice. Thus, gammaherpesviruses evade immune activation by the cytosolic DNA-sensing pathway, which, in the MHV68 model, facilitates establishment of infections.
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Affiliation(s)
- Chenglong Sun
- Department of Biomedicine, Aarhus University, DK-8000 Aarhus C, Denmark; Aarhus Research Center for Innate Immunology, Aarhus University, DK-8000 Aarhus C, Denmark
| | - Stefan A Schattgen
- Division of Infectious Diseases and Immunology, Department of Medicine, University of Massachusetts Medical School, Worcester, MA 01655
| | - Prapaporn Pisitkun
- Department of Biomedicine, Aarhus University, DK-8000 Aarhus C, Denmark; Aarhus Research Center for Innate Immunology, Aarhus University, DK-8000 Aarhus C, Denmark; Department of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand 10400
| | - Joan P Jorgensen
- Department of Biomedicine, Aarhus University, DK-8000 Aarhus C, Denmark; Aarhus Research Center for Innate Immunology, Aarhus University, DK-8000 Aarhus C, Denmark
| | - Adam T Hilterbrand
- Department of Molecular Biosciences, Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712
| | - Lucas J Wang
- Department of Molecular Biosciences, Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712
| | - John A West
- Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, Chapel Hill, NC 27599
| | - Kathrine Hansen
- Department of Biomedicine, Aarhus University, DK-8000 Aarhus C, Denmark; Aarhus Research Center for Innate Immunology, Aarhus University, DK-8000 Aarhus C, Denmark
| | - Kristy A Horan
- Department of Biomedicine, Aarhus University, DK-8000 Aarhus C, Denmark
| | - Martin R Jakobsen
- Department of Biomedicine, Aarhus University, DK-8000 Aarhus C, Denmark; Aarhus Research Center for Innate Immunology, Aarhus University, DK-8000 Aarhus C, Denmark
| | - Peter O'Hare
- Section of Virology, Faculty of Medicine, Imperial College, St. Mary's Campus, London W2 1PG, United Kingdom
| | - Heiko Adler
- Helmholtz Zentrum Munich, German Research Center for Environmental Health, D-81377 Munich, Germany
| | - Ren Sun
- Department of Molecular Biology and Medical Pharmacology, Faculty of Medicine, University of California, Los Angeles, Los Angeles, CA 90095; and
| | - Hidde L Ploegh
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142
| | - Blossom Damania
- Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, Chapel Hill, NC 27599
| | - Jason W Upton
- Department of Molecular Biosciences, Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712
| | - Katherine A Fitzgerald
- Division of Infectious Diseases and Immunology, Department of Medicine, University of Massachusetts Medical School, Worcester, MA 01655
| | - Søren R Paludan
- Department of Biomedicine, Aarhus University, DK-8000 Aarhus C, Denmark; Aarhus Research Center for Innate Immunology, Aarhus University, DK-8000 Aarhus C, Denmark;
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18
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Stack J, Doyle SL, Connolly DJ, Reinert LS, O'Keeffe KM, McLoughlin RM, Paludan SR, Bowie AG. TRAM is required for TLR2 endosomal signaling to type I IFN induction. THE JOURNAL OF IMMUNOLOGY 2014; 193:6090-102. [PMID: 25385819 DOI: 10.4049/jimmunol.1401605] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Detection of microbes by TLRs on the plasma membrane leads to the induction of proinflammatory cytokines such as TNF-α, via activation of NF-κB. Alternatively, activation of endosomal TLRs leads to the induction of type I IFNs via IFN regulatory factors (IRFs). TLR4 signaling from the plasma membrane to NF-κB via the Toll/IL-1R (TIR) adaptor protein MyD88 requires the TIR sorting adaptor Mal, whereas endosomal TLR4 signaling to IRF3 via the TIR domain-containing adaptor-inducing IFN-β (TRIF) requires the TRIF-related adaptor molecule (TRAM). Similar to TLR4 homodimers, TLR2 heterodimers can also induce both proinflammatory cytokines and type I IFNs. TLR2 plasma membrane signaling to NF-κB is known to require MyD88 and Mal, whereas endosomal IRF activation by TLR2 requires MyD88. However, it was unclear whether TLR2 requires a sorting adaptor for endosomal signaling, like TLR4 does. In this study, we show that TLR2-dependent IRF7 activation at the endosome is both Mal- and TRAM-dependent, and that TRAM is required for the TLR2-dependent movement of MyD88 to endosomes following ligand engagement. TRAM interacted with both TLR2 and MyD88, suggesting that TRAM can act as a bridging adapter between these two molecules. Furthermore, infection of macrophages lacking TRAM with herpes viruses or the bacterium Staphylococcus aureus led to impaired induction of type I IFN, indicating a role for TRAM in TLR2-dependent responses to human pathogens. Our work reveals that TRAM acts as a sorting adaptor not only for TLR4, but also for TLR2, to facilitate signaling to IRF7 at the endosome, which explains how TLR2 is capable of causing type I IFN induction.
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Affiliation(s)
- Julianne Stack
- School of Biochemistry and Immunology, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin 2, Ireland
| | - Sarah L Doyle
- School of Medicine, Trinity College Dublin, Dublin 2, Ireland; The National Children's Research Centre, Our Lady's Children's Hospital, Crumlin, Dublin 12, Ireland; and
| | - Dympna J Connolly
- School of Biochemistry and Immunology, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin 2, Ireland
| | - Line S Reinert
- Department of Biomedicine, Aarhus University, DK-8000 Aarhus C, Denmark
| | - Kate M O'Keeffe
- School of Biochemistry and Immunology, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin 2, Ireland
| | - Rachel M McLoughlin
- School of Biochemistry and Immunology, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin 2, Ireland
| | - Søren R Paludan
- Department of Biomedicine, Aarhus University, DK-8000 Aarhus C, Denmark
| | - Andrew G Bowie
- School of Biochemistry and Immunology, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin 2, Ireland;
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The gammaherpesviruses Kaposi's sarcoma-associated herpesvirus and murine gammaherpesvirus 68 modulate the Toll-like receptor-induced proinflammatory cytokine response. J Virol 2014; 88:9245-59. [PMID: 24899179 DOI: 10.1128/jvi.00841-14] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED The human pathogen Kaposi's sarcoma-associated herpesvirus (KSHV), the etiological agent of Kaposi's sarcoma, primary effusion lymphoma, and multicentric Castleman's disease, establishes lifelong latency upon infection. Murine gammaherpesvirus 68 (MHV68) is a well-established model for KSHV. Toll-like receptors (TLRs) play a crucial role for the innate immune response to pathogens. Although KSHV and MHV68 are detected by TLRs, studies suggest they modulate TLR4 and TLR9 signaling, respectively. In this study, we show that in bone marrow-derived macrophages (BMDMs), MHV68 did not induce a detectable proinflammatory cytokine response. Furthermore, MHV68 abrogated the response to TLR2, -4, -7, and -9 agonists in BMDMs. Similarly to observations with MHV68, infection with KSHV efficiently inhibited TLR2 signaling in THP-1 monocytes. Using a KSHV open reading frame (ORF) library, we found that K4.2, ORF21, ORF31, and the replication and transcription activator protein (RTA)/ORF50 inhibited TLR2-dependent nuclear factor kappa B (NF-κB) activation in HEK293 TLR2-yellow fluorescent protein (YFP)- and Flag-TLR2-transfected HEK293T cells. Of the identified ORFs, RTA/ORF50 strongly downregulated TLR2 and TLR4 signaling by reducing TLR2 and TLR4 protein expression. Confocal microscopy revealed that TLR2 and TLR4 were no longer localized to the plasma membrane in cells expressing RTA/ORF50. In this study, we have shown that the gammaherpesviruses MHV68 and KSHV efficiently downmodulate TLR signaling in macrophages and have identified a novel function of RTA/ORF50 in modulation of the innate immune response. IMPORTANCE The Toll-like receptors (TLRs) are an important class of pattern recognition receptors of the innate immune system. They induce a potent proinflammatory cytokine response upon detection of a variety of pathogens. In this study, we found that the gammaherpesviruses murine gammaherpesvirus 68 (MHV68) and Kaposi's sarcoma-associated herpesvirus (KSHV) efficiently inhibit the TLR-mediated innate immune response. We further identified the KSHV-encoded replication and transcription activator protein (RTA) as a novel modulator of TLR signaling. Our data suggest that the gammaherpesviruses MHV68 and KSHV prevent activation of the innate immune response by targeting TLR signaling.
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20
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Kaesler S, Volz T, Skabytska Y, Köberle M, Hein U, Chen KM, Guenova E, Wölbing F, Röcken M, Biedermann T. Toll-like receptor 2 ligands promote chronic atopic dermatitis through IL-4-mediated suppression of IL-10. J Allergy Clin Immunol 2014; 134:92-9. [PMID: 24698321 DOI: 10.1016/j.jaci.2014.02.017] [Citation(s) in RCA: 84] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2013] [Revised: 02/14/2014] [Accepted: 02/17/2014] [Indexed: 12/30/2022]
Abstract
BACKGROUND Atopic dermatitis (AD) is a T cell-mediated inflammatory skin disease, with TH2 cells initiating acute flares. This inflamed skin is immediately colonized with Staphylococcus aureus, which provides potent Toll-like receptor (TLR) 2 ligands. However, the effect of TLR2 ligands on the development of TH2-mediated AD inflammation remains unclear. OBJECTIVE We investigated the progression of TH2 cell-mediated dermatitis after TLR2 activation. METHODS Using models for acute AD with TH2 cells initiating cutaneous inflammation, we investigated the consequences of TLR2 activation. Dermatitis, as assessed by changes in ear skin thickness and histology, was analyzed in different BALB/c and C57BL/6 wild-type and knockout mouse strains, and immune profiling was carried out by using in vitro and ex vivo cytokine analyses. RESULTS We show that TH2 cell-mediated dermatitis is self-limiting and depends on IL-4. Activation of TLR2 converted the limited TH2 dermatitis to chronic cutaneous inflammation. We demonstrate that the concerted activation of TLR2 and IL-4 receptor on dendritic cells is sufficient for this conversion. As an underlying mechanism, we found that the combinatorial sensing of the innate TLR2 ligands and the adaptive TH2 cytokine IL-4 suppressed anti-inflammatory IL-10 and consequently led to the exacerbation and persistence of dermatitis. CONCLUSION Our data demonstrate that innate TLR2 signals convert transient TH2 cell-mediated dermatitis into persistent inflammation, as seen in chronic human AD, through IL-4-mediated suppression of IL-10. For the first time, these data show how initial AD lesions convert to chronic inflammation and provide another rationale for targeting IL-4 in patients with AD, a therapeutic approach that is currently under development.
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Affiliation(s)
- Susanne Kaesler
- Department of Dermatology, Eberhard Karls University, Tübingen, Germany
| | - Thomas Volz
- Department of Dermatology, Eberhard Karls University, Tübingen, Germany
| | - Yuliya Skabytska
- Department of Dermatology, Eberhard Karls University, Tübingen, Germany
| | - Martin Köberle
- Department of Dermatology, Eberhard Karls University, Tübingen, Germany
| | - Ulrike Hein
- Department of Dermatology, Eberhard Karls University, Tübingen, Germany
| | - Ko-Ming Chen
- Department of Dermatology, Eberhard Karls University, Tübingen, Germany
| | - Emmanuella Guenova
- Department of Dermatology, Eberhard Karls University, Tübingen, Germany; Department of Dermatology, University Hospital Zurich, Zurich, Switzerland
| | - Florian Wölbing
- Department of Dermatology, Eberhard Karls University, Tübingen, Germany
| | - Martin Röcken
- Department of Dermatology, Eberhard Karls University, Tübingen, Germany
| | - Tilo Biedermann
- Department of Dermatology, Eberhard Karls University, Tübingen, Germany; Department of Dermatology and Allergy Biederstein, Technische Universität München, Munich, Germany.
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21
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MyD88-dependent immunity to a natural model of vaccinia virus infection does not involve Toll-like receptor 2. J Virol 2014; 88:3557-67. [PMID: 24403581 DOI: 10.1128/jvi.02776-13] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED Although the pattern recognition receptor Toll-like receptor 2 (TLR2) is typically thought to recognize bacterial components, it has been described to alter the induction of both innate and adaptive immunity to a number of viruses, including vaccinia virus (VACV). However, many pathogens that reportedly encode TLR2 agonists may actually be artifactually contaminated during preparation, possibly with cellular debris or merely with molecules that sensitize cells to be activated by authentic TLR2 agonists. In both humans and mice, the most relevant natural route of infection with VACV is through intradermal infection of the skin. Therefore, we examined the requirement for TLR2 and its signaling adaptor MyD88 in protective immunity to VACV after intradermal infection. We find that although TLR2 may recognize virus preparations in vitro and have a minor role in preventing dissemination of VACV following systemic infection with large doses of virus, it is wholly disposable in both control of virus replication and induction of adaptive immunity following intradermal infection. In contrast, MyD88 is required for efficient induction of CD4 T cell and B cell responses and for local control of virus replication following intradermal infection. However, even MyD88 is not required to induce local inflammation, inflammatory cytokine production, or recruitment of cells that restrict virus from spreading systemically after peripheral infection. Thus, an effective antiviral response does require MyD88, but TLR2 is not required for control of a peripheral VACV infection. These findings emphasize the importance of studying relevant routes of infection when examining innate sensing mechanisms. IMPORTANCE Vaccinia virus (VACV) provides the backbone for some of the most widely used and successful viral vaccine vectors and is also related to the human pathogens Cantagalo virus and molluscum contagiosum virus that infect the skin of patients. Therefore, it is vital to understand the mechanisms that induce a strong innate immune response to the virus following dermal infection. Here, we compare the ability of the innate sensing molecule Toll-like receptor 2 (TLR2) and the signaling molecule MyD88 to influence the innate and adaptive immune response to VACV following systemic or dermal infection.
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22
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Cai M, Li M, Wang K, Wang S, Lu Q, Yan J, Mossman KL, Lin R, Zheng C. The herpes simplex virus 1-encoded envelope glycoprotein B activates NF-κB through the Toll-like receptor 2 and MyD88/TRAF6-dependent signaling pathway. PLoS One 2013; 8:e54586. [PMID: 23382920 PMCID: PMC3557241 DOI: 10.1371/journal.pone.0054586] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2012] [Accepted: 12/14/2012] [Indexed: 12/21/2022] Open
Abstract
The innate immune response plays a critical role in the host defense against invading pathogens, and TLR2, a member of the Toll-like receptor (TLR) family, has been implicated in the immune response and initiation of inflammatory cytokine secretion against several human viruses. Previous studies have demonstrated that infectious and ultraviolet-inactivated herpes simplex virus 1 (HSV-1) virions lead to the activation of nuclear factor kappa B (NF-κB) and secretion of proinflammatory cytokines via TLR2. However, except for the envelope glycoprotein gH and gL, whether there are other determinants of HSV-1 responsible for TLR2 mediated biological effects is not known yet. Here, we demonstrated that the HSV-1-encoded envelope glycoprotein gB displays as molecular target recognized by TLR2. gB coimmunoprecipitated with TLR2, TLR1 and TLR6 in transfected and infected human embryonic kidney (HEK) 293T cells. Treatment of TLR2-transfected HEK293T (HEK293T-TLR2) cells with purified gB results in the activation of NF-κB reporter, and this activation requires the recruitment of the adaptor molecules myeloid differentiation primary-response protein 88 (MyD88) and tumor necrosis factor receptor-associated factor 6 (TRAF6) but not CD14. Furthermore, activation of NF-κB was abrogated by anti-gB and anti-TLR2 blocking antibodies. In addition, the expression of interleukin-8 induced by gB was abrogated by the treatment of the human monocytic cell line THP-1 with anti-TLR2 blocking antibody or by the incubation of gB with anti-gB antibody. Taken together, these results indicate the importance and potency of HSV-1 gB as one of pathogen-associated molecular patterns (PAMPs) molecule recognized by TLR2 with immediate kinetics.
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Affiliation(s)
- Mingsheng Cai
- Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China
- Department of Pathogenic Biology and Immunology, Guangzhou Medical University, Guangzhou, China
- Department of Veterinary Medicine, Foshan Science and Technology University, Foshan, China
| | - Meili Li
- Department of Pathogenic Biology and Immunology, Guangzhou Medical University, Guangzhou, China
| | - Kezhen Wang
- Institute of Biology and Medical Sciences, Soochow University, Suzhou, China
- Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China
| | - Shuai Wang
- Institute of Biology and Medical Sciences, Soochow University, Suzhou, China
- Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China
| | - Qiong Lu
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Jinghua Yan
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Karen L. Mossman
- The Department of Pathology and Molecular Medicine, Institute for Infectious Disease Research, McMaster University, Hamilton, Canada
| | - Rongtuan Lin
- Lady Davis Institute for Medical Research, Jewish General Hospital and Department of Medicine, McGill University, Montreal, Canada
| | - Chunfu Zheng
- Institute of Biology and Medical Sciences, Soochow University, Suzhou, China
- Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China
- * E-mail:
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Getahun A, Smith MJ, Kogut I, van Dyk LF, Cambier JC. Retention of anergy and inhibition of antibody responses during acute γ herpesvirus 68 infection. THE JOURNAL OF IMMUNOLOGY 2012; 189:2965-74. [PMID: 22904300 DOI: 10.4049/jimmunol.1201407] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The majority of the human population becomes infected early in life by the gammaherpesvirus EBV. Some findings suggest that there is an association between EBV infection and the appearance of pathogenic Abs found in lupus. Gammaherpesvirus 68 infection of adult mice (an EBV model) was shown to induce polyclonal B cell activation and hypergammaglobulinemia, as well as increased production of autoantibodies. In this study, we explored the possibility that this breach of tolerance reflects loss of B cell anergy. Our findings show that, although anergic B cells transiently acquire an activated phenotype early during infection, they do not become responsive to autoantigen, as measured by the ability to mobilize Ca2+ following AgR cross-linking or mount Ab responses following immunization. Indeed, naive B cells also acquire an activated phenotype during acute infection but are unable to mount Ab responses to either T cell-dependent or T cell-independent Ags. In acutely infected animals, Ag stimulation leads to upregulation of costimulatory molecules and relocalization of Ag-specific B cells to the B-T cell border; however, these cells do not proliferate or differentiate into Ab-secreting cells. Adoptive-transfer experiments show that the suppressed state is reversible and is dictated by the environment in the infected host. Finally, B cells in infected mice deficient of CD4+ T cells are not suppressed, suggesting a role for CD4+ T cells in enforcing unresponsiveness. Thus, rather than promoting loss of tolerance, gammaherpesvirus 68 infection induces an immunosuppressed state, reminiscent of compensatory anti-inflammatory response syndrome.
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Affiliation(s)
- Andrew Getahun
- Integrated Department of Immunology, University of Colorado School of Medicine and National Jewish Health, Denver, CO 80206, USA
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Cai MS, Li ML, Zheng CF. Herpesviral infection and Toll-like receptor 2. Protein Cell 2012; 3:590-601. [PMID: 22865347 DOI: 10.1007/s13238-012-2059-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2012] [Accepted: 07/02/2012] [Indexed: 12/24/2022] Open
Abstract
In the last decade, substantial progress has been made in understanding the molecular mechanisms involved in the initial host responses to viral infections. Herpesviral infections can provoke an inflammatory cytokine response, however, the innate pathogen-sensing mechanisms that transduce the signal for this response are poorly understood. In recent years, it has become increasingly evident that the Toll-like receptors (TLRs), which are germline-encoded pattern recognition receptors (PRRs), function as potent sensors for infection. TLRs can induce the activation of the innate immunity by recruiting specific intracellular adaptor proteins to initiate signaling pathways, which then culminating in activation of the nuclear factor kappa B (NF-κB) and interferon-regulatory factors (IRFs) that control the transcription of genes encoding type I interferon (IFN I) and other inflammatory cytokines. Furthermore, activation of innate immunity is critical for mounting adaptive immune responses. In parallel, common mechanisms used by viruses to counteract TLR-mediated responses or to actively subvert these pathways that block recognition and signaling through TLRs for their own benefit are emerging. Recent findings have demonstrated that TLR2 plays a crucial role in initiating the inflammatory process, and surprisingly that the response TLR2 triggers might be overzealous in its attempt to counter the attack by the virus. In this review, we summarize and discuss the recent advances about the specific role of TLR2 in triggering inflammatory responses in herpesvirus infection and the consequences of the alarms raised in the host that they are assigned to protect.
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Affiliation(s)
- Ming-sheng Cai
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China
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25
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Milk matters: soluble Toll-like receptor 2 (sTLR2) in breast milk significantly inhibits HIV-1 infection and inflammation. PLoS One 2012; 7:e40138. [PMID: 22792230 PMCID: PMC3391222 DOI: 10.1371/journal.pone.0040138] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2012] [Accepted: 06/01/2012] [Indexed: 11/24/2022] Open
Abstract
The majority of infants who breastfeed from their HIV-positive mothers remain uninfected despite constant and repeated exposure to virus over weeks to years. This phenomenon is not fully understood but has been closely linked to innate factors in breast milk (BM). Most recently we have focused on one such innate factor, soluble Toll-like receptor 2 (sTLR2) for its significant contribution as an inhibitor of inflammation triggered by bacterial and viral antigens. We hypothesized that sTLR2 in BM inhibits immune activation/inflammation and HIV-1 infection. sTLR2 protein profiles were analyzed in HIV-uninfected BM and showed dramatic variability in expression concentration and predominant sTLR2 forms between women. sTLR2 immunodepleted BM, versus mock-depleted BM, incubated with Pam3CSK4 lead to significant increases in IL-8 production in a TLR2-dependant fashion in U937, HEK293-TLR2, and Caco-2. Importantly, TLR2-specific polyclonal and monoclonal antibody addition to BM prior to cell-free R5 HIV-1 addition led to significantly (P<0.01, P<0.001, respectively) increased HIV-1 infection in TZM-bl reporter cells. To confirm these findings, sTLR2-depletion in BM led to significantly (P<0.001) increased HIV-1 infection in TZM-bl cells. Notably, immunodepletion does not allow for the complete removal of sTLR2 from BM, thus functional testing shown here may underestimate the total effect elicited by sTLR2 against HIV-1 and synthetic bacterial ligand. This study provides evidence for the first time that sTLR2 in BM may provide a dual protective role for infants breastfeeding from their HIV-infected mothers by; (1) immunomodulating pro-inflammatory responses to bacterial ligands, and (2) directly inhibiting cell-free HIV-1 infection. Thus, sTLR2 in BM may be critical to infant health and prove beneficial in decreasing vertical HIV-1 transmission to infants.
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Davis JM, Knutson KL, Skinner JA, Strausbauch MA, Crowson CS, Therneau TM, Wettstein PJ, Matteson EL, Gabriel SE. A profile of immune response to herpesvirus is associated with radiographic joint damage in rheumatoid arthritis. Arthritis Res Ther 2012; 14:R24. [PMID: 22293286 PMCID: PMC3392817 DOI: 10.1186/ar3706] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2011] [Revised: 12/23/2011] [Accepted: 01/31/2012] [Indexed: 12/18/2022] Open
Abstract
Introduction Progression of joint damage despite appropriate therapy remains a significant problem for patients with rheumatoid arthritis (RA). This study was undertaken to identify profiles of immune response that correlate with radiographic joint damage as a first step toward the discovery of new pathogenic mechanisms of joint destruction in RA. Methods The study included 58 patients with RA and 15 healthy controls. The profiles of cytokine release from peripheral blood mononuclear cells (PBMC) in response to stimulation for 48 hours with one of six stimuli, or in media alone, were measured. Immune response profiles identified for each stimulus were correlated with radiographic joint damage as defined by the Sharp-van der Heijde score (SHS), before and after multivariable adjustment. For profiles correlated with the SHS, the distributions of individual cytokines were evaluated in patients according to the severity of joint damage and compared to healthy controls. Results The immune response profile for cytomegalovirus (CMV)/Epstein-Barr virus (EBV) stimulation was correlated with both the SHS total and erosion scores (r = 0.31, P = 0.018 and r = 0.33, P = 0.011, respectively). After adjusting for age, sex, disease duration, autoantibody status, CMV/EBV serological status, current disease activity, disability and treatments, the correlation of the CMV/EBV immune response and the SHS erosion score became stronger (r = 0.43, P < 0.003). The CMV/EBV immune response correlated with CMV IgG (r = 0.44, P < 0.001), but not with EBV IgG. The most important cytokines for the CMV/EBV immune response profile were IFN-γ, IL-2, IL-4, IL-5, IL-13 and IL-17A, all of which are associated with T-cell immunity. Both the summary immune response score and the individual responses of IFN-γ and IL-13 to CMV/EBV stimulation were associated with greater joint damage. Conclusions A profile of immune response to purified CMV/EBV lysates is associated with radiographic joint damage. The correlation of this immune response to CMV serology implies possible involvement of latent CMV infection. Therefore, the findings suggest that the immune response to latent CMV infection could play a fundamental role in the progression of inflammation and structural joint damage in patients with RA.
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Affiliation(s)
- John M Davis
- Division of Rheumatology, Department of Medicine, College of Medicine, Mayo Clinic; 200 First Street SW, Rochester, MN 55905, USA.
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27
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Faure M, Rabourdin-Combe C. Innate immunity modulation in virus entry. Curr Opin Virol 2011; 1:6-12. [PMID: 22440562 PMCID: PMC7102793 DOI: 10.1016/j.coviro.2011.05.013] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2011] [Revised: 05/23/2011] [Accepted: 05/24/2011] [Indexed: 02/07/2023]
Abstract
Entry into a cell submits viruses to detection by pattern recognition receptors (PRRs) leading to an early innate anti-viral response. Several viruses evolved strategies to avoid or subvert PRR recognition at the step of virus entry to promote infection. Whereas viruses mostly escape from soluble PRR detection, endocytic/phagocytic PRRs, such as the mannose receptor or DC-SIGN, are commonly used for virus entry. Moreover, virion-incorporated proteins may also offer viruses a way to dampen anti-viral innate immunity upon virus entry, and entering viruses might usurp autophagy to improve their own infectivity.
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28
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Pezda AC, Penn A, Barton GM, Coscoy L. Suppression of TLR9 immunostimulatory motifs in the genome of a gammaherpesvirus. THE JOURNAL OF IMMUNOLOGY 2011; 187:887-96. [PMID: 21666062 DOI: 10.4049/jimmunol.1003737] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Multiple receptors within the innate immune system have evolved to recognize nucleic acids as signatures of viral infection. It is believed that this specificity is essential for viral detection, as viruses often lack other invariant features that can serve as suitable targets for innate receptors. One such innate receptor, TLR9, has been implicated in the detection of many dsDNA viruses. In this study, we investigate the detection of murine gammaherpesvirus 68 (MHV68) by TLR9. We find that the genomic DNA of the murine CMV, a very potent inducer of innate responses. Genome-wide analysis of the number of stimulatory versus nonstimulatory CpG motifs present in the genome of each virus reveals that the MHV68 genome contains only a fraction of the number of immunostimulatory motifs present in murine CMV. Notably, MHV68 appears to have selectively suppressed the number of stimulatory motifs through cytosine to thymine conversion. These data suggest that certain viruses may have evolved and modified their genomic content to avoid recognition by nucleic acid-sensing receptors of the innate immune system.
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Affiliation(s)
- Andrea C Pezda
- Division of Immunology and Pathogenesis, Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
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Rathinam VAK, Fitzgerald KA. Innate immune sensing of DNA viruses. Virology 2011; 411:153-62. [PMID: 21334037 DOI: 10.1016/j.virol.2011.02.003] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2010] [Revised: 12/31/2010] [Accepted: 02/02/2011] [Indexed: 12/13/2022]
Abstract
DNA viruses are a significant contributor to human morbidity and mortality. The immune system protects against viral infections through coordinated innate and adaptive immune responses. While the antigen-specific adaptive mechanisms have been extensively studied, the critical contributions of innate immunity to anti-viral defenses have only been revealed in the very recent past. Central to these anti-viral defenses is the recognition of viral pathogens by a diverse set of germ-line encoded receptors that survey nearly all cellular compartments for the presence of pathogens. In this review, we discuss the recent advances in the innate immune sensing of DNA viruses and focus on the recognition mechanisms involved.
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Affiliation(s)
- Vijay A K Rathinam
- Department of Medicine, University of Massachusetts Medical School, Worcester, MA 01605, USA
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