BH3-only protein Puma contributes to death of antigen-specific T cells during shutdown of an immune response to acute viral infection

Abstract Recent findings have shown that a small subset of IL-15 dependent CD8+ regulatory T cells is essential for maintenance of self- tolerance and prevention of autoimmune disease in mice (Kim et al., Nature 2010). These CD8+ T cells target CD4+ follicular T helper (TFH) cells through recognition of the murine class Ib MHC molecule Qa-1 (HLA-E in man), resulting in perforin-dependent elimination of target cells and diminished antibody production in the steady state and during disease. This analysis was based on generation of Qa-1 knock-in mice (D227K mice) that harbor a single Qa-1 D→K amino acid exchange point mutation at position 227 that abrogates binding of Qa-1/peptide to the CD8/TCR complex. B6.Qa-1 D227K mutant mice develop severe autoimmune disease marked by generation of autoantibodies to multiple tissues, lymphocyte infiltration into non-lymphoid tissues and lethal glomerulonephritis. Qa-1-restricted CD8+ Treg are characterized by the CD44+CD122+Ly49+ phenotype (Kim et al., PNAS 2011). Here, we analyzed the contribution of CD8+ Treg to modulation of the anti-viral immune response. Virus-specific CD8+ cytotoxic T cells are of central importance for successful control of the Lymphocytic Choriomeningitis Virus (LCMV). LCMV clone 13, however, a genetic variant of LCMV Armstrong, persists in the host and chronic antigen exposure leads to exhaustion of CD8+ T cells and continuous tissue inflammation. The contribution of CD8+ Treg in the anti-viral immune response to acute and chronic viral infection remained elusive so far. We found that CD8+ Treg not only control self-tolerance but also diminish the immune response to viral infection. By comparing wild-type and D227K mutant mice after infection with LCMV Armstrong or LCMV clone 13, we observed in both cases reduced effector CD8+ T cell responses. This was true for polyclonal CD44+CD62L– CD8+ T cells as well as LCMV-specific gp33+ effector CD8+ T cells. During acute infection KLRG1+CD127-CD44+CD62L- cells (short-lived effector CD8+ cells) (Joshi et al., Immunity 2007) were particularly diminished as well as effector cytokines in wild-type mice compared to D227K mice. In contrast, increased effector responses in D227K mice resulted in enhanced control of virus and reduced inflammation of tissues. During chronic infection with LCMV, wild-type mice become severely ill and present with a pronounced clinical phenotype. Increased effector CD8+ T cell immune responses in D227K mice resulted in dramatic alleviation of disease. During late stage of chronic infection, D227K mice showed enhanced virus control and reduced tissue pathology compared with wild-type mice. Interestingly, expression of inhibitory receptors such as PD-1, 2B4 and LAG3 were increased in wild-type mice whereas activating receptors such as NKG2D and KLRG1 were increased in D227K mice, resulting in a memory phenotype in D227K mice compared with exhausted CD8+ T cells in wild-type mice. Adoptive transfer experiments revealed that CD8+ Treg directly suppress CD8+ target cells and thereby inhibit induction of a robust anti-viral response. Taken together, we show that Qa-1-restricted CD8+ Treg have a direct inhibitory effect on effector CD8+ T cells during acute and chronic viral infection, resulting in a more violent disease and diminished recovery. These data suggest that depletion or inactivation of CD8+ Treg represents a potentially effective strategy to enhance anti-viral immunity. Disclosures: No relevant conflicts of interest to declare.

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Lineage-Plasticity and Inflammatory Change of Human FoxP3+ Regulatory T Cells in Acute Viral Infection: Implication in Immune-Mediated Tissue Injury

Blood ◽

10.1182/blood.v124.21.4132.4132 ◽

2014 ◽

Vol 124 (21) ◽

pp. 4132-4132

Author(s):

Yoon Seok Choi ◽

Jeewon Lee ◽

Ik-Chan Song ◽

Deog-Yeon Jo ◽

Eui-Cheol Shin

Keyword(s):

T Cells ◽

Viral Infection ◽

Treg Cell ◽

Liver Damage ◽

Cd4 T Cells ◽

Treg Cells ◽

Suppressive Activity ◽

Suppressive Function ◽

Acute Viral Infection ◽

Tnf Α

Abstract FoxP3+ CD4+CD25hi regulatory T (Treg) cells play a major role in maintaining the immune homeostasis by preventing the activation of self-reactive T cells as well as in controlling a series of immune responses in viral infections. Recent studies suggest that lineage-commitment of CD4+T cells, including Treg cells, is not a fixed fate, rather a status with a wide range of plasticity. Functional changes and lineage-plasticity of Treg cells during acute viral infection, especially of human, have not been reported so far. Herein, we investigated whether Treg cells show the functional plasticity and whether such changes can affect the regulation of immunopathology in a human acute viral infection. As a model of human acute viral infection, we used a cohort of patients with acute hepatitis A (AHA), since tissue (liver) injury in AHA is mediated exclusively by activated T cells, not by direct cytopathic effect of virus. To assess the plasticity of Treg cell lineage, first, we examined the production of a variety of inflammatory cytokines from Treg cells following T cell receptor (TCR) stimulation of peripheral blood lymphocytes with anti-CD3/CD28 antibody, using intracellular cytokine staining and multicolor flow cytometry. We found that a significant proportion of FoxP3+ CD4+CD25hi Treg cells produced TNF-α following TCR stimulation in patients with AHA, but not in heathy subjects. Analyses at multiple time points during the course of infection showed that TNF-α production from Treg cells decreased in convalescent phase. Likewise, we observed that liver-infiltrating Treg cells also produced TNF-α after TCR stimulation. Moreover, highly-purified CD4+CD25hiCD127lo/-Treg cells could also produce TNF-α following TCR stimulation, indicating that Treg cells of AHA patients can produce TNF-α in direct response to TCR stimulation. Next, to exclude the possibility that TNF-α might be secreted from transiently FoxP3-expressing activated non-Treg CD4+ T cells, we examined the expression level of CD127 on TNF-α-secreting FoxP3+ CD4+ T cells. TNF-α+ Treg cells expressed CD127 in the level similar to conventional TNF-α- counterpart, and CD127 expression levels of both Treg populations were much lower than FoxP3- CD4+ T cells. Furthermore, DNA methylation analysis of Treg cell-specific demethylated region (TSDR) after sorting TNF-α+ Treg cells revealed completely demethylated pattern in highly conserved CpG island of FOXP3 gene. These findings support that TNF-α is produced from bona fide Treg cells, not from FoxP3-expressing activated non-Treg CD4+T cells. In analysis of immunophenotypes, TNF-α+ Treg cells were enriched in CD45RA-FoxP3lo population, implying their reduced in vivo suppressive activity. Along with the lower level of FoxP3, TNF-α+ Treg cells showed lower level of CD39 expression, a surrogate marker of Treg cell suppressive activity, compared to TNF-α- Treg cells. Furthermore, TNF-α+Treg cells showed a robust evidence of lineage-plasticity toward Th17 lineage, expressing a key transcription factor RORγt. Consistently, they expressed CCR6 and co-produced IL-17A following TCR stimulation, which are the hallmark of Th17 effector function. To analyze the clinical implication of attenuate suppressive function and plasticity shown by TNF-α+ Treg cells, we examined correlation between production of proinflammatory cytokines from Treg cells and severity of liver damage in AHA. As a result, proportion of TNF-α-producing Treg cells closely and linearly correlated with severity of liver damage, suggesting the critical role of TNF-α+ Treg cells in the immunopathogenesis of AHA. However, Treg cell suppression assay in the absence or presence of anti-TNF-α antibody showed that Treg cell suppressive function was not affected by TNF-α blockade. This indicates that attenuated function of TNF-α+Treg cells is not attributed simply to production of a kind of inflammatory cytokine, rather to more complicated reprogramming mechanism. Taken together, these data provide a clear evidence of attenuated suppressive activity and Th17-toward lineage plasticity of FoxP3+ Treg cells, represented by TNF-α production, in a human acute viral infection. Also, we suggest one possible mechanism that lineage plasticity and inflammatory changes of Treg cells could be implicated in the immunopathogenesis of human diseases. Disclosures No relevant conflicts of interest to declare.

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Dynamics of the Cytotoxic T Cell Response to a Model of Acute Viral Infection

Journal of Virology ◽

10.1128/jvi.03474-14 ◽

2015 ◽

Vol 89 (8) ◽

pp. 4517-4526 ◽

Cited By ~ 71

Author(s):

William S. DeWitt ◽

Ryan O. Emerson ◽

Paul Lindau ◽

Marissa Vignali ◽

Thomas M. Snyder ◽

...

Keyword(s):

Immune Response ◽

T Cell ◽

Viral Infection ◽

High Throughput Sequencing ◽

Cell Receptor ◽

Cell Repertoire ◽

T Cell Clones ◽

Cell Clones ◽

Acute Viral Infection

ABSTRACTA detailed characterization of the dynamics and breadth of the immune response to an acute viral infection, as well as the determinants of recruitment to immunological memory, can greatly contribute to our basic understanding of the mechanics of the human immune system and can ultimately guide the design of effective vaccines. In addition to neutralizing antibodies, T cells have been shown to be critical for the effective resolution of acute viral infections. We report the first in-depth analysis of the dynamics of the CD8+T cell repertoire at the level of individual T cell clonal lineages upon vaccination of human volunteers with a single dose of YF-17D. This live attenuated yellow fever virus vaccine yields sterile, long-term immunity and has been previously used as a model to understand the immune response to a controlled acute viral infection. We identified and enumerated unique CD8+T cell clones specifically induced by this vaccine through a combined experimental and statistical approach that included high-throughput sequencing of the CDR3 variable region of the T cell receptor β-chain and an algorithm that detected significantly expanded T cell clones. This allowed us to establish that (i) on average, ∼2,000 CD8+T cell clones were induced by YF-17D, (ii) 5 to 6% of the responding clones were recruited to long-term memory 3 months postvaccination, (iii) the most highly expanded effector clones were preferentially recruited to the memory compartment, and (iv) a fraction of the YF-17D-induced clones could be identified from peripheral blood lymphocytes solely by measuring clonal expansion.IMPORTANCEThe exhaustive investigation of pathogen-induced effector T cells is essential to accurately quantify the dynamics of the human immune response. The yellow fever vaccine (YFV) has been broadly used as a model to understand how a controlled, self-resolving acute viral infection induces an effective and long-term protective immune response. Here, we extend this previous work by reporting the identity of activated effector T cell clones that expand in response to the YFV 2 weeks postvaccination (as defined by their unique T cell receptor gene sequence) and by tracking clones that enter the memory compartment 3 months postvaccination. This is the first study to use high-throughput sequencing of immune cells to characterize the breadth of the antiviral effector cell response and to determine the contribution of unique virus-induced clones to the long-lived memory T cell repertoire. Thus, this study establishes a benchmark against which future vaccines can be compared to predict their efficacy.

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Regulatory T cells expressing granzyme B play a critical role in controlling lung inflammation during acute viral infection

Mucosal Immunology ◽

10.1038/mi.2011.62 ◽

2012 ◽

Vol 5 (2) ◽

pp. 161-172 ◽

Cited By ~ 105

Author(s):

J Loebbermann ◽

H Thornton ◽

L Durant ◽

T Sparwasser ◽

K E Webster ◽

...

Keyword(s):

T Cells ◽

Regulatory T Cells ◽

Viral Infection ◽

Lung Inflammation ◽

Granzyme B ◽

Critical Role ◽

Acute Viral Infection

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Extrinsic Acquisition of CD80 by Antigen-Specific CD8+ T Cells Regulates Their Recall Immune Responses to Acute Viral Infection

Immune Network ◽

10.4110/in.2019.19.e25 ◽

2019 ◽

Vol 19 (4) ◽

Author(s):

Jimin Son ◽

Sang-Jun Ha

Keyword(s):

T Cells ◽

Immune Responses ◽

Viral Infection ◽

Cd8 T Cells ◽

Acute Viral Infection

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Characterization of CD4-Positive Lymphocytes in the Antiviral Response of Olive Flounder (Paralichthys oliveceus) to Nervous Necrosis Virus

International Journal of Molecular Sciences ◽

10.3390/ijms21114180 ◽

2020 ◽

Vol 21 (11) ◽

pp. 4180

Author(s):

Jae Wook Jung ◽

Jin Hong Chun ◽

Jung Seok Lee ◽

Si Won Kim ◽

Ae Rin Lee ◽

...

Keyword(s):

Flow Cytometry ◽

Immune Response ◽

T Cells ◽

T Cell ◽

T Lymphocytes ◽

Viral Infection ◽

T Cell Subsets ◽

Olive Flounder ◽

Flow Cytometry Analysis ◽

Color Flow

The presence of CD4 T lymphocytes has been described for several teleost species, while many of the main T cell subsets have not been characterized at a cellular level, because of a lack of suitable tools for their identification, e.g., monoclonal antibodies (mAbs) against cell markers. We previously described the tissue distribution and immune response related to CD3ε and CD4-1 T cells in olive flounder (Paralichthys oliveceus) in response to a viral infection. In the present study, we successfully produce an mAb against CD4-2 T lymphocytes from olive flounder and confirmed its specificity using immuno-blotting, immunofluorescence staining, flow cytometry analysis and reverse transcription polymerase chain reaction (RT-PCR). Using these mAbs, we were able to demonstrate that the CD3ε T cell populations contain both types of CD4+ cells, with the majority of the CD4 T cell subpopulations being CD4-1+/CD4-2+ cells, determined using two-color flow cytometry analysis. We also examined the functional activity of the CD4-1 and CD4-2 cells in vivo in response to a viral infection, with the numbers of both types of CD4 T cells increasing significantly during the virus infection. Collectively, these findings suggest that the CD4 T lymphocytes in olive flounder are equivalent to the helper T cells in mammals in terms of their properties and function, and it is the CD4-2 T lymphocytes rather than the CD4-1 T cells that play an important role in the Th1 immune response against viral infections in olive flounder.

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