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Kundura L, Cezar R, André S, Campos-Mora M, Lozano C, Vincent T, Muller L, Lefrant JY, Roger C, Claret PG, Duvnjak S, Loubet P, Sotto A, Tran TA, Estaquier J, Corbeau P. Low perforin expression in CD8+ T lymphocytes during the acute phase of severe SARS-CoV-2 infection predicts long COVID. Front Immunol 2022; 13:1029006. [PMID: 36341327 PMCID: PMC9630742 DOI: 10.3389/fimmu.2022.1029006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2022] [Accepted: 10/03/2022] [Indexed: 11/26/2022] Open
Abstract
T cell cytotoxicity plays a major role in antiviral immunity. Anti-SARS-CoV-2 immunity may determine acute disease severity, but also the potential persistence of symptoms (long COVID). We therefore measured the expression of perforin, a cytotoxic mediator, in T cells of patients recently hospitalized for SARS-CoV-2 infection. We recruited 54 volunteers confirmed as being SARS-CoV-2-infected by RT-PCR and admitted to Intensive Care Units (ICUs) or non-ICU, and 29 age- and sex-matched healthy controls (HCs). Amounts of intracellular perforin and granzyme-B, as well as cell surface expression of the degranulation marker CD107A were determined by flow cytometry. The levels of 15 cytokines in plasma were measured by Luminex. The frequency of perforin-positive T4 cells and T8 cells was higher in patients than in HCs (9.9 ± 10.1% versus 4.6 ± 6.4%, p = 0.006 and 46.7 ± 20.6% vs 33.3 ± 18.8%, p = 0.004, respectively). Perforin expression was neither correlated with clinical and biological markers of disease severity nor predictive of death. By contrast, the percentage of perforin-positive T8 cells in the acute phase of the disease predicted the onset of long COVID one year later. A low T8 cytotoxicity in the first days of SARS-CoV-2 infection might favor virus replication and persistence, autoimmunity, and/or reactivation of other viruses such as Epstein-Barr virus or cytomegalovirus, paving the way for long COVID. Under this hypothesis, boosting T cell cytotoxicity during the acute phase of the infection could prevent delayed sequelae.
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Affiliation(s)
- Lucy Kundura
- Institute of Human Genetics, Unité Mixte de Recherche 9002 (UMR9002), Centre National de Recherche Scientifique (CNRS) and Montpellier University, Montpellier, France
- *Correspondence: Lucy Kundura,
| | - Renaud Cezar
- Immunology Department, Nîmes University Hospital, Nîmes, France
| | - Sonia André
- Institut National de la Santé et de la Recherche Médicale (INSERM) U1124, Université Paris Cité, Paris, France
| | - Mauricio Campos-Mora
- Institute for Regenerative Medicine & Biotherapy, Montpellier University Hospital, Montpellier, France
| | - Claire Lozano
- Immunology Department, Montpellier University Hospital, Montpellier, France
| | - Thierry Vincent
- Immunology Department, Montpellier University Hospital, Montpellier, France
| | - Laurent Muller
- Surgical Intensive Care Department, Nîmes University Hospital, Nîmes, France
| | - Jean-Yves Lefrant
- Surgical Intensive Care Department, Nîmes University Hospital, Nîmes, France
| | - Claire Roger
- Surgical Intensive Care Department, Nîmes University Hospital, Nîmes, France
| | - Pierre-Géraud Claret
- Medical and Surgical Emergency Department, Nîmes University Hospital, Nîmes, France
| | - Sandra Duvnjak
- Gerontology Department, Nîmes University Hospital, Nîmes, France
| | - Paul Loubet
- Infectious diseases Department, Nîmes University Hospital, Nîmes, France
| | - Albert Sotto
- Infectious diseases Department, Nîmes University Hospital, Nîmes, France
| | - Tu-Ahn Tran
- Pediatrics Department, Nîmes University Hospital, Nîmes, France
| | - Jérôme Estaquier
- Institut National de la Santé et de la Recherche Médicale (INSERM) U1124, Université Paris Cité, Paris, France
- Québec University Hospital, CHU de Québec, Laval University Research Center, Quebec City, QC, Canada
| | - Pierre Corbeau
- Institute of Human Genetics, Unité Mixte de Recherche 9002 (UMR9002), Centre National de Recherche Scientifique (CNRS) and Montpellier University, Montpellier, France
- Immunology Department, Nîmes University Hospital, Nîmes, France
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2
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Preglej T, Ellmeier W. CD4 + Cytotoxic T cells - Phenotype, Function and Transcriptional Networks Controlling Their Differentiation Pathways. Immunol Lett 2022; 247:27-42. [PMID: 35568324 DOI: 10.1016/j.imlet.2022.05.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2022] [Revised: 05/09/2022] [Accepted: 05/10/2022] [Indexed: 11/05/2022]
Abstract
The two major subsets of peripheral T cells are classically divided into the CD4+ T helper cells and the cytotoxic CD8+ T cell lineage. However, the appearance of some effector CD4+ T cell populations displaying cytotoxic activity, in particular during viral infections, has been observed, thus breaking the functional dichotomy of CD4+ and CD8+ T lymphocytes. The strong association of the appearance of CD4+ cytotoxic T lymphocytes (CD4 CTLs) with viral infections suggests an important role of this subset in antiviral immunity by controlling viral replication and infection. Moreover, CD4 CTLs have been linked with anti-tumor activity and might also cause immunopathology in autoimmune diseases. This raises interest into the molecular mechanisms regulating CD4 CTL differentiation, which are poorly understood in comparison to differentiation pathways of other Th subsets. In this review, we provide a brief overview about key features of CD4 CTLs, including their role in viral infections and cancer immunity, and about the link between CD4 CTLs and immune-mediated diseases. Subsequently, we will discuss the current knowledge about transcriptional and epigenetic networks controlling CD4 CTL differentiation and highlight recent data suggesting a role for histone deacetylases in the generation of CD4 CTLs.
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Affiliation(s)
- Teresa Preglej
- Division of Rheumatology, Department of Internal Medicine III, Medical University of Vienna
| | - Wilfried Ellmeier
- Division of Immunobiology, Institute of Immunology, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna.
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3
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Petro TM. IFN Regulatory Factor 3 in Health and Disease. THE JOURNAL OF IMMUNOLOGY 2021; 205:1981-1989. [PMID: 33020188 DOI: 10.4049/jimmunol.2000462] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Accepted: 07/07/2020] [Indexed: 12/14/2022]
Abstract
Immunity to viruses requires an array of critical cellular proteins that include IFN regulatory factor 3 (IRF3). Consequently, most viruses that infect vertebrates encode proteins that interfere with IRF3 activation. This review describes the cellular pathways linked to IRF3 activation and where those pathways are targeted by human viral pathogens. Moreover, key regulatory pathways that control IRF3 are discussed. Besides viral infections, IRF3 is also involved in resistance to some bacterial infections, in anticancer immunity, and in anticancer therapies involving DNA damage agents. A recent finding shows that IRF3 is needed for T cell effector functions that are involved in anticancer immunity and also in T cell autoimmune diseases. In contrast, unregulated IRF3 activity is clearly not beneficial, considering it is implicated in certain interferonopathies, in which heightened IRF3 activity leads to IFN-β-induced disease. Therefore, IRF3 is involved largely in maintaining health but sometimes contributing to disease.
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Affiliation(s)
- Thomas M Petro
- Department of Oral Biology, University of Nebraska Medical Center, Lincoln, NE 68583; and Nebraska Center for Virology, University of Nebraska Medical Center, Lincoln, NE 68583
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4
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PD-L1 overexpression in EBV-positive gastric cancer is caused by unique genomic or epigenomic mechanisms. Sci Rep 2021; 11:1982. [PMID: 33479394 PMCID: PMC7820576 DOI: 10.1038/s41598-021-81667-w] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Accepted: 01/04/2021] [Indexed: 12/21/2022] Open
Abstract
Epstein-Barr virus-positive gastric cancer [EBV (+) GC] is a distinct GC subtype with unique genetic and epigenetic aberrations. Here, we examined resected GC samples and publicly available microarray data and The Cancer Genome Atlas (TCGA) database to identify the mechanism underlying overexpression of PD-L1 in EBV (+) GC. We found that high levels of PD-L1 overexpression in EBV (+) GC were caused by focal amplification of CD274. By contrast, relatively high expression of PD-L1 in tumor tissue and infiltrating immune cells correlated with CD8 lymphocyte infiltration and IFN-γ expression via IRF3 activation. Since we reported previously that PD-L1 expression is associated both with the presence of CD8 T cells in the tumor microenvironment and with IFN-γ expression in GC, we examined a database to see whether IFN-γ-associated overexpression of PD-L1 plays a significant role in EBV (+) GC. Immunohistochemical staining showed that expression of the IRF3 signature in clinical GC samples was higher in EBV (+) than in EBV (−) cases. The data presented herein reveal a unique dual mechanism underlying PD-L1 overexpression in EBV (+) GC: high focal amplification of CD274 or IFN-γ-mediated signaling via activation of IRF3.
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Gerhauser I, Hansmann F, Ciurkiewicz M, Löscher W, Beineke A. Facets of Theiler's Murine Encephalomyelitis Virus-Induced Diseases: An Update. Int J Mol Sci 2019; 20:ijms20020448. [PMID: 30669615 PMCID: PMC6358740 DOI: 10.3390/ijms20020448] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Revised: 01/15/2019] [Accepted: 01/18/2019] [Indexed: 12/31/2022] Open
Abstract
Theiler’s murine encephalomyelitis virus (TMEV), a naturally occurring, enteric pathogen of mice is a Cardiovirus of the Picornaviridae family. Low neurovirulent TMEV strains such as BeAn cause a severe demyelinating disease in susceptible SJL mice following intracerebral infection. Furthermore, TMEV infections of C57BL/6 mice cause acute polioencephalitis initiating a process of epileptogenesis that results in spontaneous recurrent epileptic seizures in approximately 50% of affected mice. Moreover, C3H mice develop cardiac lesions after an intraperitoneal high-dose application of TMEV. Consequently, TMEV-induced diseases are widely used as animal models for multiple sclerosis, epilepsy, and myocarditis. The present review summarizes morphological lesions and pathogenic mechanisms triggered by TMEV with a special focus on the development of hippocampal degeneration and seizures in C57BL/6 mice as well as demyelination in the spinal cord in SJL mice. Furthermore, a detailed description of innate and adaptive immune responses is given. TMEV studies provide novel insights into the complexity of organ- and mouse strain-specific immunopathology and help to identify factors critical for virus persistence.
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Affiliation(s)
- Ingo Gerhauser
- Department of Pathology, University of Veterinary Medicine, Bünteweg 17, 30559 Hannover, Germany.
| | - Florian Hansmann
- Department of Pathology, University of Veterinary Medicine, Bünteweg 17, 30559 Hannover, Germany.
- Center for System Neuroscience, 30559 Hannover, Germany.
| | - Malgorzata Ciurkiewicz
- Department of Pathology, University of Veterinary Medicine, Bünteweg 17, 30559 Hannover, Germany.
- Center for System Neuroscience, 30559 Hannover, Germany.
| | - Wolfgang Löscher
- Center for System Neuroscience, 30559 Hannover, Germany.
- Department of Pharmacology, University of Veterinary Medicine, Bünteweg 17, 30559 Hannover, Germany.
| | - Andreas Beineke
- Department of Pathology, University of Veterinary Medicine, Bünteweg 17, 30559 Hannover, Germany.
- Center for System Neuroscience, 30559 Hannover, Germany.
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Schultz KLW, Troisi EM, Baxter VK, Glowinski R, Griffin DE. Interferon regulatory factors 3 and 7 have distinct roles in the pathogenesis of alphavirus encephalomyelitis. J Gen Virol 2018; 100:46-62. [PMID: 30451651 DOI: 10.1099/jgv.0.001174] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Interferon (IFN) regulatory factors (IRFs) are important determinants of the innate response to infection. We evaluated the role(s) of combined and individual IRF deficiencies in the outcome of infection of C57BL/6 mice with Sindbis virus, an alphavirus that infects neurons and causes encephalomyelitis. The brain and spinal cord levels of Irf7, but not Irf3 mRNAs, were increased after infection. IRF3/5/7-/- and IRF3/7-/- mice died within 3-4 days with uncontrolled virus replication, similar to IFNα receptor-deficient mice, while all wild-type (WT) mice recovered. IRF3-/- and IRF7-/- mice had brain levels of IFNα that were lower, but brain and spinal cord levels of IFNβ and IFN-stimulated gene mRNAs that were similar to or higher than WT mice without detectable serum IFN or increases in Ifna or Ifnb mRNAs in the lymph nodes, indicating that the differences in outcome were not due to deficiencies in the central nervous system (CNS) type I IFN response. IRF3-/- mice developed persistent neurological deficits and had more spinal cord inflammation and higher CNS levels of Il1b and Ifnγ mRNAs than WT mice, but all mice survived. IRF7-/- mice died 5-8 days after infection with rapidly progressive paralysis and differed from both WT and IRF3-/- mice in the induction of higher CNS levels of IFNβ, tumour necrosis factor (TNF) α and Cxcl13 mRNA, delayed virus clearance and more extensive cell death. Therefore, fatal disease in IRF7-/- mice is likely due to immune-mediated neurotoxicity associated with failure to regulate the production of inflammatory cytokines such as TNFα in the CNS.
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Affiliation(s)
- Kimberly L W Schultz
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA.,†Present address: Food and Drug Administration, Silver Spring, MD 20993, USA
| | - Elizabeth M Troisi
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA
| | - Victoria K Baxter
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA.,‡Present address: University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Rebecca Glowinski
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA.,§Present address: Ohio State University College of Medicine, Columbus, OH 43210, USA
| | - Diane E Griffin
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA
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7
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Guinn Z, Brown DM, Petro TM. Activation of IRF3 contributes to IFN-γ and ISG54 expression during the immune responses to B16F10 tumor growth. Int Immunopharmacol 2017; 50:121-129. [PMID: 28651122 PMCID: PMC5548377 DOI: 10.1016/j.intimp.2017.06.016] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Revised: 06/15/2017] [Accepted: 06/17/2017] [Indexed: 12/22/2022]
Abstract
Interferon Regulatory Factor (IRF-3) has been shown to contribute to immune control of B16 melanoma tumor growth. We have shown previously that IRF-3 has a role in IFN-γ-induced expression of pro-apoptotic interferon stimulated gene 54 (ISG54) in macrophages and IFN-γ in T cells. To investigate the IRF3-IFN-γ-ISG54 nexus, we injected C57Bl/6 (B6) and IRF3KO mice s.c. with luciferase-producing B16-F10 tumor cells. Tumor growth as measured by luciferase levels was similar between B6 and IRF3KO mice at days 2 and 6, but was significantly greater at day 9 in IRF3KO mice compared with B6 mice. Transcription factor assays on splenic protein extracts after tumor inoculation revealed peak activation of IRF3 and IRF7 at day 6 in B6 tumor-bearing mice but not in IRF3KO tumor-bearing mice. Likewise, significant induction of IFN-γ occurred in spleens and tumors in B6 mice from days 6-9 but failed to occur in tumor-bearing IRF3KO mice. Previous reports from other labs showed that the anti-tumor properties of IFN-γ are the result of cell cycle arrest. Using B16F1 cells or B16F1 cells deficient in IFN-γ receptor (B16-IRFGRKO), we found that IFN-γ alone and in synergy with the TLR3/IRF3 agonists, poly I:C, decreased B16F1 cell growth in significant correlation with increased ISG54 expression. Moreover, IFN-γ alone increased expression of the cell cycle inhibitor, p27Kip while IFN-γ plus poly I:C increased cleaved Caspase-3 in B16 cells. Thus, it is likely that an IFN-γ/IRF3/ISG54 nexus can significantly contribute to tumor cell control during anti-tumor immune responses.
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Affiliation(s)
- Zachary Guinn
- School of Biological Sciences, University of Nebraska-Lincoln, United States
| | - Deborah M Brown
- School of Biological Sciences, University of Nebraska-Lincoln, United States; Nebraska Center for Virology, University of Nebraska-Lincoln, United States
| | - Thomas M Petro
- Nebraska Center for Virology, University of Nebraska-Lincoln, United States; Department of Oral Biology, University of Nebraska Medical Center, Lincoln, NE, United States.
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8
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Juno JA, van Bockel D, Kent SJ, Kelleher AD, Zaunders JJ, Munier CML. Cytotoxic CD4 T Cells-Friend or Foe during Viral Infection? Front Immunol 2017; 8:19. [PMID: 28167943 PMCID: PMC5253382 DOI: 10.3389/fimmu.2017.00019] [Citation(s) in RCA: 134] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Accepted: 01/05/2017] [Indexed: 01/03/2023] Open
Abstract
CD4 T cells with cytotoxic function were once thought to be an artifact due to long-term in vitro cultures but have in more recent years become accepted and reported in the literature in response to a number of viral infections. In this review, we focus on cytotoxic CD4 T cells in the context of human viral infections and in some infections that affect mice and non-human primates. We examine the effector mechanisms used by cytotoxic CD4 cells, the phenotypes that describe this population, and the transcription factors and pathways that lead to their induction following infection. We further consider the cells that are the predominant targets of this effector subset and describe the viral infections in which CD4 cytotoxic T lymphocytes have been shown to play a protective or pathologic role. Cytotoxic CD4 T cells are detected in the circulation at much higher levels than previously realized and are now recognized to have an important role in the immune response to viral infections.
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Affiliation(s)
- Jennifer A Juno
- Department of Microbiology and Immunology, Peter Doherty Institute, University of Melbourne , Melbourne, VIC , Australia
| | - David van Bockel
- Immunovirology and Pathogenesis Program, The Kirby Institute for Infection and Immunity in Society, University of New South Wales Australia , Sydney, NSW , Australia
| | - Stephen J Kent
- Department of Microbiology and Immunology, Peter Doherty Institute, University of Melbourne, Melbourne, VIC, Australia; Melbourne Sexual Health Centre, Department of Infectious Diseases, Alfred Health, Central Clinical School, Monash University, Melbourne, VIC, Australia; ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, University of Melbourne, Parkville, VIC, Australia
| | - Anthony D Kelleher
- Immunovirology and Pathogenesis Program, The Kirby Institute for Infection and Immunity in Society, University of New South Wales Australia, Sydney, NSW, Australia; St Vincent's Hospital, Sydney, NSW, Australia
| | - John J Zaunders
- Immunovirology and Pathogenesis Program, The Kirby Institute for Infection and Immunity in Society, University of New South Wales Australia, Sydney, NSW, Australia; St Vincent's Hospital, Sydney, NSW, Australia
| | - C Mee Ling Munier
- Immunovirology and Pathogenesis Program, The Kirby Institute for Infection and Immunity in Society, University of New South Wales Australia , Sydney, NSW , Australia
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Guinn Z, Lampe AT, Brown DM, Petro TM. Significant role for IRF3 in both T cell and APC effector functions during T cell responses. Cell Immunol 2016; 310:141-149. [PMID: 27641636 DOI: 10.1016/j.cellimm.2016.08.015] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Revised: 08/16/2016] [Accepted: 08/30/2016] [Indexed: 12/31/2022]
Abstract
Interferon Regulatory Factor (IRF)3 is a crucial transcription factor during innate immune responses. Here we show IRF3 also has a role in adaptive T cell immune responses. Expression of IFN-γ, IL-17, and Granzyme B (GrB) during in vitro T cell responses was impaired when either dendritic cells (DCs) or T cells were derived from IRF3KO mice. Unexpectedly, IRF3-dependent NK-activating molecule (INAM), which is an NK cell activating factor of the DC innate immune response, was induced during the T cell response. Additionally, supernatants from responding T cells induced ISG54 in the RAW264.7 macrophage cell line in an IRF3 dependent manner. Moreover, addition of anti-IFN-γ prevented supernatant induction of ISG54 and recombinant IFN-γ stimulated ISG54 expression. Thus, IRF3 in APCs and T cells is required for optimal T-cell effector function and the ability of T cells to influence innate immune function of APCs.
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Affiliation(s)
- Zacharey Guinn
- School of Biological Sciences, University of Nebraska-Lincoln, United States
| | - Anna T Lampe
- School of Biological Sciences, University of Nebraska-Lincoln, United States
| | - Deborah M Brown
- School of Biological Sciences, University of Nebraska-Lincoln, United States; Nebraska Center for Virology, University of Nebraska-Lincoln, United States
| | - Thomas M Petro
- Nebraska Center for Virology, University of Nebraska-Lincoln, United States; Department of Oral Biology, University of Nebraska Medical Center, Lincoln, NE, United States.
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10
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Brown DM, Lampe AT, Workman AM. The Differentiation and Protective Function of Cytolytic CD4 T Cells in Influenza Infection. Front Immunol 2016; 7:93. [PMID: 27014272 PMCID: PMC4783394 DOI: 10.3389/fimmu.2016.00093] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2016] [Accepted: 02/25/2016] [Indexed: 12/24/2022] Open
Abstract
CD4 T cells that recognize peptide antigen in the context of class II MHC can differentiate into various subsets that are characterized by their helper functions. However, increasing evidence indicates that CD4 cells with direct cytolytic activity (CD4 CTL) play a role in chronic as well as acute infections, such as influenza A virus (IAV) infection. In the last couple of decades, techniques to measure the frequency and activity of these cytolytic cells has demonstrated their abundance in infections, such as human immunodeficiency virus, mouse pox, murine gamma herpes virus, cytomegalovirus, Epstein-Barr virus, and influenza among others. We now appreciate a greater role for CD4 CTL as direct effectors in viral infections and antitumor immunity through their ability to acquire perforin-mediated cytolytic activity and contribution to lysis of virally infected targets or tumors. As early as the 1980s, CD4 T cell clones with cytolytic potential were identified after influenza virus infection, yet much of this early work was dependent on in vitro culture and little was known about the physiological relevance of CD4 CTL. Here, we discuss the direct role CD4 CTL play in protection against lethal IAV infection and the factors that drive the generation of perforin-mediated lytic activity in CD4 cells in vivo during IAV infection. While focusing on CD4 CTL generated during IAV infection, we pull comparisons from the literature in other antiviral and antitumor systems. Further, we highlight what is currently known about CD4 CTL secondary and memory responses, as well as vaccination strategies to induce these potent killer cells that provide an extra layer of cell-mediated immune protection against heterosubtypic IAV infection.
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Affiliation(s)
- Deborah M Brown
- School of Biological Sciences, University of Nebraska-Lincoln, Lincoln, NE, USA; Nebraska Center for Virology, University of Nebraska-Lincoln, Lincoln, NE, USA
| | - Anna T Lampe
- School of Biological Sciences, University of Nebraska-Lincoln, Lincoln, NE, USA; Nebraska Center for Virology, University of Nebraska-Lincoln, Lincoln, NE, USA
| | - Aspen M Workman
- Nebraska Center for Virology, University of Nebraska-Lincoln , Lincoln, NE , USA
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