Isolevuglandin-Modified Cardiac Proteins Drive CD4+ T Cell Activation in the Heart and Promote Cardiac Dysfunction

Background: Despite the well-established association between T cell-mediated inflammation and non-ischemic heart failure (HF), the specific mechanisms triggering T cell activation during the progression of HF and the antigens involved are poorly understood. We hypothesized that myocardial oxidative stress induces the formation of isolevuglandin (IsoLG)-modified proteins that function as cardiac neoantigens to elicit CD4+ T cell receptor (TCR) activation and promote HF. Methods: We used transverse aortic constriction (TAC) in mice to trigger myocardial oxidative stress and T cell infiltration. We profiled the TCR repertoire by mRNA sequencing of intramyocardial activated CD4+ T cells in Nur77 GFP reporter mice, which transiently express GFP upon TCR engagement. We assessed the role of antigen presentation and TCR specificity in the development of cardiac dysfunction using antigen presentation-deficient MhcII -/- mice, and TCR transgenic OTII mice that lack specificity for endogenous antigens. We detected IsoLG-protein adducts in failing human hearts. We also evaluated the role of reactive oxygen species (ROS) and IsoLGs in eliciting T cell immune responses in vivo by treating mice with the antioxidant TEMPOL, and the IsoLG scavenger 2-hydroxybenzylamine (2-HOBA) during TAC, and ex-vivo in mechanistic studies of CD4+ T cell proliferation in response to IsoLG-modified cardiac proteins. Results: We discovered that TCR antigen recognition increases in the left ventricle (LV) as cardiac dysfunction progresses, and identified a limited repertoire of activated CD4+ T cell clonotypes in the LV. Antigen presentation of endogenous antigens was required to develop cardiac dysfunction since MhcII -/- mice reconstituted with CD4+ T cells, and OTII mice immunized with their cognate antigen were protected from TAC-induced cardiac dysfunction despite the presence of LV-infiltrated CD4+ T cells. Scavenging IsoLGs with 2-HOBA reduced TCR activation and prevented cardiac dysfunction. Mechanistically, cardiac pressure overload resulted in ROS dependent dendritic cell accumulation of IsoLG-protein adducts which induced robust CD4+ T cell proliferation. Conclusions: Collectively, our study demonstrates an important role of ROS-induced formation of IsoLG-modified cardiac neoantigens that lead to TCR-dependent CD4+ T cell activation within the heart.

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Antigen Display, T-Cell Activation, and Immune Evasion during Acute and Chronic Ehrlichiosis

Infection and Immunity ◽

10.1128/iai.01433-08 ◽

2009 ◽

Vol 77 (10) ◽

pp. 4643-4653 ◽

Cited By ~ 14

Author(s):

Bisweswar Nandi ◽

Madhumouli Chatterjee ◽

Kathryn Hogle ◽

Maura McLaughlin ◽

Katherine MacNamara ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

Antigen Presentation ◽

Cell Line ◽

T Cell Activation ◽

Cd4 T Cells ◽

Chronic Infection ◽

Cell Activation ◽

Cd4 T Cell ◽

Anatomical Location

ABSTRACT How spatial and temporal changes in major histocompatibility complex/peptide antigen presentation to CD4 T cells regulate CD4 T-cell responses during intracellular bacterial infections is relatively unexplored. We have shown that immunization with an ehrlichial outer membrane protein, OMP-19, protects mice against fatal ehrlichial challenge infection, and we identified a CD4 T-cell epitope (IAb/OMP-19107-122) that elicited CD4 T cells following either immunization or infection. Here, we have used an IAb/OMP-19107-122-specific T-cell line to monitor antigen display ex vivo during acute and chronic infection with Ehrlichia muris, a bacterium that establishes persistent infection in C57BL/6 mice. The display of IAb/OMP-19107-122 by host antigen-presenting cells was detected by measuring intracellular gamma interferon (IFN-γ) production by the T-cell line. After intravenous infection, antigen presentation was detected in the spleen, peritoneal exudate cells, and lymph nodes, although the kinetics of antigen display differed among the tissues. Antigen presentation and bacterial colonization were closely linked in each anatomical location, and there was a direct relationship between antigen display and CD4 T-cell effector function. Spleen and lymph node dendritic cells (DCs) were efficient presenters of IAb/OMP-19107-122, demonstrating that DCs play an important role in ehrlichial infection and immunity. Chronic infection and antigen presentation occurred within the peritoneal cavity, even in the presence of highly activated CD4 T cells. These data indicated that the ehrlichiae maintain chronic infection not by inhibiting antigen presentation or T-cell activation but, in part, by avoiding signals mediated by activated T cells.

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HIV-specific T-cell Responses and Generalized Activation in HIV-1 Infected Long-term Non-progressors and Progressors from South India

Current HIV Research ◽

10.2174/1570162x17666181212122607 ◽

2019 ◽

Vol 16 (4) ◽

pp. 302-314

Author(s):

Chinnambedu Ravichandran Swathirajan ◽

Ramachandran Vignesh ◽

Greer Waldrop ◽

Uma Shanmugasundaram ◽

Pannerselvam Nandagopal ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

T Cell Activation ◽

Cell Activation ◽

Cd4 T Cell ◽

Cell Responses ◽

Activation Rates ◽

Hiv 1

Background:Anti-viral cytokine expressions by cytotoxic T-cells and lower activation rates have been reported to correlate with suppressed HIV replication in long-term non-progressors (LTNP). Immune mechanisms underlying disease non-progression in LTNP might vary with HIV-1 subtype and geographical locations.Objective:This study evaluates cytokine expression and T-cells activation in relation to disease non-progression in LTNP.Methods:HIV-1 Subtype C infected LTNP (n=20) and progressors (n=15) were enrolled and flowcytometry assays were performed to study HIV-specific CD8 T-cells expressing IL-2, IFN-γ, TNF-α and MIP-1β against gag and env peptides. CD4+ T-cell activation was evaluated by surface expression of HLADR and CD38.Results:Proportions of cytokines studied did not differ significantly between LTNP and progressors, while contrasting correlations with disease progression markers were observed in LTNP. CD4+ T-cell activation rates were significantly lower in LTNP compared to progressors which indicate the potential role of T-cell activation rates in disease non-progression in LTNP.Conclusion:LTNP and progressors showed similar CD8+ T-cell responses, but final conclusions can be drawn only by comparing multiple immune factors in larger LTNP cohort with HIV-1 infected individuals at various levels of disease progression. A possible role of HIV-1 subtype variation and ethnic differences in addition to host-genetic and viral factors cannot be ruled out.

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Contact-dependent delivery of IL-2 by dendritic cells to CD4 T cells in the contraction phase promotes their long-term survival

Protein & Cell ◽

10.1007/s13238-019-00662-0 ◽

2019 ◽

Vol 11 (2) ◽

pp. 108-123

Author(s):

Dan Tong ◽

Li Zhang ◽

Fei Ning ◽

Ying Xu ◽

Xiaoyu Hu ◽

...

Keyword(s):

T Cells ◽

Dendritic Cells ◽

T Cell ◽

T Cell Activation ◽

Cd4 T Cells ◽

Cell Activation ◽

Cd4 T Cell ◽

Immune Memory ◽

Term Survival

Abstract Common γ chain cytokines are important for immune memory formation. Among them, the role of IL-2 remains to be fully explored. It has been suggested that this cytokine is critically needed in the late phase of primary CD4 T cell activation. Lack of IL-2 at this stage sets for a diminished recall response in subsequent challenges. However, as IL-2 peak production is over at this point, the source and the exact mechanism that promotes its production remain elusive. We report here that resting, previously antigen-stimulated CD4 T cells maintain a minimalist response to dendritic cells after their peak activation in vitro. This subtle activation event may be induced by DCs without overt presence of antigen and appears to be stronger if IL-2 comes from the same dendritic cells. This encounter reactivates a miniature IL-2 production and leads a gene expression profile change in these previously activated CD4 T cells. The CD4 T cells so experienced show enhanced reactivation intensity upon secondary challenges later on. Although mostly relying on in vitro evidence, our work may implicate a subtle programing for CD4 T cell survival after primary activation in vivo.

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IL10-Deficiency in CD4+ T Cells Exacerbates the IFNγ and IL17 Response During Bacteria Induced Colitis

Cellular Physiology and Biochemistry ◽

10.1159/000430295 ◽

2015 ◽

Vol 36 (4) ◽

pp. 1259-1273 ◽

Cited By ~ 9

Author(s):

Virginia Seiffart ◽

Julia Zoeller ◽

Robert Klopfleisch ◽

Munisch Wadwa ◽

Wiebke Hansen ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

Regulatory T Cells ◽

T Cell Activation ◽

Cd4 T Cells ◽

Cell Activation ◽

Intestinal Inflammation ◽

Cd4 T Cell ◽

Intestinal Homeostasis ◽

Crypt Hyperplasia

Background/Aims: IL10 is a key inhibitor of effector T cell activation and a mediator of intestinal homeostasis. In addition, IL10 has emerged as a key immunoregulator during infection with various pathogens, ameliorating the excessive T-cell responses that are responsible for much of the immunopathology associated with the infection. Because IL10 plays an important role in both intestinal homeostasis and infection, we studied the function of IL10 in infection-associated intestinal inflammation. Methods: Wildtype mice and mice deficient in CD4+ T cell-derived or regulatory T cells-derived IL10 were infected with the enteric pathogen Citrobacter (C.) rodentium and analyzed for the specific immune response and pathogloy in the colon. Results: We found that IL10 expression is upregulated in colonic tissue after infection with C. rodentium, especially in CD4+ T cells, macrophages and dendritic cells. Whereas the deletion of IL10 in regulatory T cells had no effect on C. rodentium induced colitis, infection of mice deficient in CD4+ T cell-derived IL10 exhibited faster clearance of the bacterial burden but worse colitis, crypt hyperplasia, and pathology than did WT mice. In addition, the depletion of CD4+ T cell-derived IL10 in infected animals was accompanied by an accelerated IFNγ and IL17 response in the colon. Conclusion: Thus, we conclude that CD4+ T cell-derived IL10 is strongly involved in the control of C. rodentium-induced colitis. Interference with this network could have implications for the treatment of infection-associated intestinal inflammation.

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Modulation of LPS-Induced CD4+ T-Cell Activation and Apoptosis by Antioxidants in Untreated Asymptomatic HIV Infected Participants: AnIn VitroStudy

Clinical and Developmental Immunology ◽

10.1155/2013/631063 ◽

2013 ◽

Vol 2013 ◽

pp. 1-9 ◽

Cited By ~ 8

Author(s):

S. Mburu ◽

J. L. Marnewick ◽

A. Abayomi ◽

H. Ipp

Keyword(s):

T Cells ◽

T Cell ◽

Vitamin C ◽

T Cell Activation ◽

Cd4 T Cells ◽

Cell Activation ◽

Annexin V ◽

Cd4 T Cell ◽

Hiv Positive ◽

Cd25 Expression

Persistent immune activation characterises HIV infection and is associated with depletion of CD4+ T-cells and increased risk of disease progression. Early loss of gut mucosal integrity results in the translocation of microbial products such as lipopolysaccharide (LPS) into the systemic circulation. This is an important source of on-going immune stimulation. The purpose of this study was to determine levels of CD4+ T-cell activation (%CD25 expression) and apoptosis (% annexin V/7-AAD) in asymptomatic, untreated HIV infection at baseline and after stimulation with LPS and incubation with or without vitamin C and N-acetylcysteine. LPS induced a significant (P<0.03) increase in %CD25 expression, annexin V, and 7-AAD in HIV positive individuals. NAC in combination with vitamin C, significantly (P=0.0018) reduced activation and early apoptosis of CD4+ T-cells to a greater degree than with either antioxidant alone. Certain combinations of antioxidants could be important in reducing the harmful effects of chronic immune activation and thereby limit CD4+ T-cell depletion. Importantly, we showed that CD4+ T-cells of the HIV positive group responded better to a combination of the antioxidants at this stage than those of the controls. Therefore, appropriate intervention at this asymptomatic stage could rescue the cells before repetitive activation results in the death of CD4+ T-cells.

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The Inflammation Signaling Molecule ATP Regulates Human CD4+ T Cell Functions

Blood ◽

10.1182/blood.v116.21.3901.3901 ◽

2010 ◽

Vol 116 (21) ◽

pp. 3901-3901

Author(s):

Sara Trabanelli ◽

Darina Očadlíková ◽

Sara Gulinelli ◽

Antonio Curti ◽

Francesco di Virgilio ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

T Cell Activation ◽

Cd4 T Cells ◽

Cell Activation ◽

Extracellular Atp ◽

Cd4 T Cell ◽

Cell Functions ◽

Atp Concentration ◽

High Concentrations

Abstract Abstract 3901 Adenosine 5'-triphosphate (ATP) is emerging as an extracellular signaling molecule playing a pivotal role in several cellular processes, through specific cell membrane purinergic P2 receptors (P2Rs). Under physiological conditions, ATP is present in the extracellular space at low concentrations (1-10 nM), whereas during inflammation and tumor cell growth ATP is present in the extracellular space at high concentrations, when 5–10 mM of ATP are quickly released from cytoplasm following plasma membrane damage or membrane stretching. For these reasons, extracellular ATP, via activation of P2Rs, might be an important regulator of inflammatory and immune response. CD4+ T cells are often exposed to different ATP concentrations in healthy or in injured/inflamed tissues. In the present study, we investigated the expression of purinergic P2 receptors (P2Rs) on human activated and regulatory CD4+ T cells and tested the lymphocyte functions in presence of low (1-10 nM), intermediate (250 nM) and high (1 mM) concentration of extracellular ATP. We assessed CD4+ T cells proliferation, apoptosis, phenotype, cytokine release, migration and matrix/cells adhesion. We show that activated CD4+ T cells express all P2Rs subtypes, whereas Tregs do not express P2X6 and P2Y2. At a functional level, low concentrations of extracellular ATP do not modulate CD4+ T cell functions. An increase in ATP concentration (250 nM) stimulates CD4+ T cells during activation: activated CD4+ T cells enhance their proliferation, the secretion of several cytokines critical for T cell functions (IL-2, IL-1b, IFN-g, IL-8), the expression of adhesion molecules (CD49d and CD54) and the capacity to adhere to cellular matrix or to other cells. Tregs seem to be unaffected by 250 nM of ATP. In contrast, high concentrations of ATP (1 mM) “turn off” activated CD4+ T cells and “turn on” Tregs. 1 mM of ATP inhibits activation of CD4+ T cells, by enhancing apoptosis and diminishing proliferation, cell-adhesion and the release of pro-inflammatory cytokines. Conversely, 1 mM of ATP attracts Tregs and stimulates their proliferation and their capacity to adhere to other cells. Moreover, Tregs cultured in presence of 1 mM of extracellular ATP are more efficient in inhibiting T cell proliferation. In summary, the present data show that the concentration of extracellular ATP regulates CD4+ T cell functions. Low ATP concentrations, as in physiological conditions, do not affect CD4+ T cell functions, whereas any enhancement of ATP concentration alters CD4+ T cell behavior. Specifically, a small increase stimulates CD4+ T cell activation, whereas a high increase inhibits CD4+ T cell activation and promotes the immunosuppression Tregs-mediated. We propose that the present in vitro data might explain how in vivo ATP regulates the behavior of activated CD4+ T cells and Tregs in case of inflammation or tumor cell growth. A small enhancement of ATP concentration occurs at the beginning of an inflammatory state or at the first stages of tumor growth; these ATP concentrations alert CD4+ T cells to the presence of a possible damage, which does not yet require Tregs involvement. In contrast, in case of severe inflammation, high ATP concentrations might prevent a further involvement of activated CD4+ T cells and promotes Tregs recruitment, avoiding hyper-inflammation. In case of advanced stages of tumorigenesis, high ATP concentration might be a tumor-escape mechanism, by killing activated CD4+ T cells and by attracting Tregs to surround the tumor. Disclosures: No relevant conflicts of interest to declare.

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HuR Plays a Positive Role to Strengthen the Signaling Pathways of CD4+ T Cell Activation and Th17 Cell Differentiation

Journal of Immunology Research ◽

10.1155/2021/9937243 ◽

2021 ◽

Vol 2021 ◽

pp. 1-13

Author(s):

Shiguang Yu ◽

Morgan Tripod ◽

Ulus Atasoy ◽

Jing Chen

Keyword(s):

T Cells ◽

T Cell ◽

Signaling Pathways ◽

T Cell Activation ◽

Cd4 T Cells ◽

Th17 Cell ◽

Th17 Cells ◽

Cell Activation ◽

Cd4 T Cell ◽

Th17 Cell Differentiation

After antigen and/or different cytokine stimulation, CD4+ T cells activated and differentiated into distinct T helper (Th) cells via differential T cell signaling pathways. Transcriptional regulation of the activation and differentiation of naïve CD4+ T cells into distinct lineage Th cells such as Th17 cells has been fully studied. However, the role of RNA-binding protein HuR in the signaling pathways of their activation and differentiation has not been well characterized. Here, we used HuR conditional knockout (HuR KO) CD4+ T cells to study mechanisms underlying HuR regulation of T cell activation and differentiation through distinct signaling pathways. Our work showed that, mechanistically, HuR positively promoted CD3g expression by binding its mRNA and enhanced the expression of downstream adaptor Zap70 and Malt1 in activated CD4+ T cells. Compared to WT Th0 cells, HuR KO Th0 cells with reduced Bcl-2 expression are much more susceptible to apoptosis than WT Th0 cells. We also found that HuR stabilized IL-6Rα mRNA and promoted IL-6Rα protein expression, thereby upregulating its downstream phosphorylation of Jak1 and Stat3 and increased level of phosphorylation of IκBα to facilitate Th17 cell differentiation. However, knockout of HuR increased IL-22 production in Th17 cells, which was due to HuR deficiency in reducing IL-22 transcription repressor c-Maf expression. These results highlight the importance of HuR in TCR signaling and IL-6/IL-6R axis driving naïve CD4+ T cell activation and differentiation into Th17 cells.

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Tuberculosis Antigen-Specific T-Cell Responses During the First 6 Months of Antiretroviral Treatment

The Journal of Infectious Diseases ◽

10.1093/infdis/jiz417 ◽

2019 ◽

Vol 221 (1) ◽

pp. 162-167 ◽

Cited By ~ 3

Author(s):

Catherine Riou ◽

Nishtha Jhilmeet ◽

Molebogeng X Rangaka ◽

Robert J Wilkinson ◽

Katalin A Wilkinson

Keyword(s):

T Cells ◽

T Cell ◽

T Cell Activation ◽

Cd4 T Cells ◽

Antiretroviral Treatment ◽

Cell Activation ◽

T Cell Subsets ◽

Cd4 T Cell ◽

Immune Memory ◽

Tuberculosis Antigen

Abstract The reconstitution of Mycobacterium tuberculosis antigen-specific CD4 T cells in a cohort of HIV-infected persons starting antiretroviral treatment (ART) in a high tuberculosis endemic area is described. Restoration of the antigen-specific CD4 T-cell subsets mirrored the overall CD4 T-cell compartment. Activation (assessed by HLA-DR expression) decreased during ART but remained elevated compared to HIV-uninfected persons. Despite known M. tuberculosis sensitization determined by interferon-γ release assay, 12/23 participants had no M. tuberculosis-specific CD4 T cells detectable by flow cytometry, combined with overall elevated T-cell activation and memory differentiation, suggesting heightened turnover. Our data suggest early ART initiation to maintain polyfunctional immune memory responses.

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Hepatic AAV Gene Transfer of Cytoplasmic Transgene Induces Transgene Product-Specific T Cell Activation Initially in the Liver and Celiac Lymph Node Preceding Treg Induction

Blood ◽

10.1182/blood.v126.23.3241.3241 ◽

2015 ◽

Vol 126 (23) ◽

pp. 3241-3241

Author(s):

Roland W. Herzog ◽

George Q. Perrin

Keyword(s):

T Cells ◽

Lymph Node ◽

T Cell ◽

Gene Transfer ◽

Antigen Presentation ◽

T Cell Activation ◽

Cd4 T Cells ◽

Cell Activation ◽

Lymphoid Organs ◽

Activated T Cells

Abstract In several published studies, we have shown induction of immune tolerance to coagulations factors by hepatic gene transfer to animals with hemophilia. Tolerance induction is influenced by a number of complex factors, most notably T cell activation and induction of antigen-specific CD4+CD25+FoxP3+ regulatory T cells (Treg). We sought to better understand antigen presentation to CD4+ T cells and the dynamics of the resulting T cell response. To characterize the interaction of adeno-associated virus (AAV) antigen expression in the liver with immune cells, we used an AAV8 vector, which have a high tropism for murine liver, expressing cytoplasmic ovalbumin (AAV8-Cyto-Ova) from the EF1α promoter. Use of AAV8-Cyto-Ova allowed us to eliminate effects from systemic antigen delivery. Vector was injected into the tail vein of DO11.10-transgenic RAG-/- mice, which contain exclusively Ova-specific CD4+ T cells and lack Treg. AAV8-Cyto-Ova caused upregulation of the very early activation marker CD69 on the CD4+ T cells as early as 2 weeks after gene transfer, with induced Treg emerging at about 3 weeks. CD69+CD4+ T cells were first observed in greatest numbers in the liver and celiac lymph node (LN), one of the liver-draining LN. This T cell activation persisted for several weeks. To better define the sites of T cell activation, we used the compound FTY720, which is an agonist of sphingosine-1-phosphate receptors and prevents migration of lymphocytes but does not alter T cell function. Two weeks after AAV8-Cyto-Ova, FTY720 sequestered activated T cells mostly in the liver and celiac LN, when compared to other lymphoid organs, indicating that these are the initial sites of T cell activation. At the 3-week time point, there were fewer activated T cells in the liver and celiac LN in mice that received FTY720, while instead accumulating in the blood. Most likely, activated T cells were prevented from reentering the lymphoid organs from the circulation, where they were sequestered. We conclude that T cells are first activated by AAV8-Cyto-Ova in the liver and celiac LN after two weeks, where they subsequently egress into the circulation and re-enter lymphoid tissues, with many returning to the liver and celiac LN. FTY720 given at 2 weeks prevented the newly activated T cells from leaving the liver and celiac LN. These results strongly suggest that antigen presentation and CD4+ T cell activation occur first in the liver and celiac LN, beginning about 2 weeks after vector administration. Consistent with this conclusion, adoptively transferred Ova-specific CD4+ T cells proliferated first and to a much greater degree in the celiac LN of AAV8-Cyto-Ova transduced mice. Inactiviating Kupffer cells with gadolinium chloride significantly reduced antigen-specific proliferation, illustrating the requirement for professional resident liver antigen-presenting cells. Furthermore, we show that - in contrast to the AAV expression of secreted Ova - Treg are exclusively extrathymically induced after AAV8-Cyto-Ova vector administration. These Treg are found in high numbers in the blood after 2 weeks in mice given the FTY720 compound, suggesting that these peripherally induced Treg quickly enter the circulation. In conclusion, the liver and its draining celiac LN are key sites for antigen presentation and T cell activation in response to transgene expression directed by hepatic gene transfer. Presentation of antigen derived from a non-secreted transgene product induces FoxP3+ Treg that rapidly distribute through the circulation. Disclosures Herzog: Novo Nordisk: Research Funding; Spark Therapeutics: Patents & Royalties: Patent licenses.

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