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Type I interferon suppresses de novo virus-specific CD4 Th1 immunity during an established persistent viral infection.

ABSTRACT: CD4 T cells are central to orchestrate, sustain, and potentially regenerate antiviral immunity throughout persistent viral infections. Although the evolving immune environment during persistent infection reshapes established CD4 T-cell responses, the fate of naïve CD4 T cells primed in the midst of persistent infection is unclear. We demonstrate that, in marked contrast to the onset of infection, virus-specific CD4 T cells primed during an established persistent infection have diminished ability to develop Th1 responses, to efficiently accumulate in peripheral tissues, and almost exclusively differentiate into T follicular helper cells. Consistent with suppressed Th1 and heightened Tfh differentiation, virus-specific CD4 T cells primed during the established persistent infection provide help to B cells, but only limited help to CD8 T cells. The suppression of de novo Th1 generation and tissue distribution was mediated by chronic type I IFN (IFN-I) production and was effectively restored by blocking IFN-I signaling during CD4 T-cell priming. Thus, we establish a suppressive function of chronic IFN-I signaling and mechanism of immunoregulation during an established persistent virus infection.

SUBMITTER: Osokine I

PROVIDER: S-EPMC4034239 | biostudies-literature | 2014 May

REPOSITORIES: biostudies-literature

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Type I interferon suppresses de novo virus-specific CD4 Th1 immunity during an established persistent viral infection.

Osokine Ivan I Snell Laura M LM Cunningham Cameron R CR Yamada Douglas H DH Wilson Elizabeth B EB Elsaesser Heidi J HJ de la Torre Juan Carlos JC Brooks David D

Proceedings of the National Academy of Sciences of the United States of America 20140505 20

CD4 T cells are central to orchestrate, sustain, and potentially regenerate antiviral immunity throughout persistent viral infections. Although the evolving immune environment during persistent infection reshapes established CD4 T-cell responses, the fate of naïve CD4 T cells primed in the midst of persistent infection is unclear. We demonstrate that, in marked contrast to the onset of infection, virus-specific CD4 T cells primed during an established persistent infection have diminished ability ...[more]

PMID: 24799699

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Project description:In most patients, current antiretroviral therapy (ART) regimens can rapidly reduce plasma viral load. However, even after years of effective treatment, a significant proportion of patients show residual plasma viremia below the clinical detection limit. Although residual viremia might be associated with increased chronic immune activation and morbidity, its origin and its potential role in the replenishment of the viral reservoir during suppressive ART is not completely understood. We performed an in-depth genetic analysis of the total and episomal cell-associated viral DNA (vDNA) repertoire in purified CD4(+) T cell subsets of three HIV-infected individuals, and used phylogenetic analysis to explore its relationship with plasma viruses.The predominant proviral reservoir was established in naïve or memory (central and transitional) CD4(+) T cell subsets in patients harboring X4- or R5-tropic viruses, respectively. Regardless of the viral tropism, most plasma viruses detected under suppressive ART resembled the proviral reservoir identified in effector and transitional memory CD4(+) T-cell subsets in blood, suggesting that residual viremia originates from these cells in either blood or lymphoid tissue. Most importantly, sequences in episomal vDNA in CD4(+) T-cells were not well represented in residual viremia.Viral tropism determines the differential distribution of viral reservoir among CD4(+) T-cell subsets. In spite of viral tropism, the effector and transitional memory CD4(+) T-cells subsets are the main source of residual viremia during suppressive ART, even though their contribution to the total proviral pool is small. However, the lack of concordance between residual viremia and viral variants driving de novo infection of CD4(+) T cells on ART may reflect the predominance of defective plasma HIV RNA genomes. These findings highlight the need for monitoring the multiple viral RNA/DNA persistence markers, based on their differential contribution to viral persistence.

Project description:Influenza A virus (IAV) is an airborne pathogen that causes significant morbidity and mortality each year. Macrophages (Mϕ) are the first immune population to encounter IAV virions in the lungs and are required to control infection. In the present study, we explored the mechanism by which cytokine signaling regulates the phenotype and function of Mϕ via epigenetic modification of chromatin. We have found that type I interferon (IFN-I) potently upregulates the lysine methyltransferase Setdb2 in murine and human Mϕ, and in turn Setdb2 regulates Mϕ-mediated immunity in response to IAV. The induction of Setdb2 by IFN-I was significantly impaired upon inhibition of the JAK-STAT signaling cascade, and chromatin immunoprecipitation revealed that both STAT1 and interferon regulatory factor 7 bind upstream of the transcription start site to induce expression. The generation of Setdb2LacZ reporter mice revealed that IAV infection results in systemic upregulation of Setdb2 in myeloid cells. In the lungs, alveolar Mϕ expressed the highest level of Setdb2, with greater than 70% lacZ positive on day 4 post-infection. Silencing Setdb2 activity in Mϕ in vivo enhanced survival in lethal IAV infection. Enhanced host protection correlated with an amplified antiviral response and less obstruction to the airways. By tri-methylating H3K9, Setdb2 silenced the transcription of Mx1 and Isg15, antiviral effectors that inhibit IAV replication. Accordingly, a reduced viral load in knockout mice on day 8 post-infection was linked to elevated Isg15 and Mx1 transcript in the lungs. In addition, Setdb2 suppressed the expression of a large number of other genes with proinflammatory or immunomodulatory function. This included Ccl2, a chemokine that signals through CCR2 to regulate monocyte recruitment to infectious sites. Consistently, knockout mice produced more CCL2 upon IAV infection and this correlated with a 2-fold increase in the number of inflammatory monocytes and alveolar Mϕ in the lungs. Finally, Setdb2 expression by Mϕ suppressed IL-2, IL-10, and IFN-γ production by CD4+ T cells in vitro, as well as proliferation in IAV-infected lungs. Collectively, these findings identify Setdb2 as a novel regulator of the immune system in acute respiratory viral infection.

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Type I interferon suppresses de novo virus-specific CD4 Th1 immunity during an established persistent viral infection.

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Type I interferon suppresses de novo virus-specific CD4 Th1 immunity during an established persistent viral infection.

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