scholarly journals The T-cell anergy induced by Leishmania amazonensis antigens is related with defective antigen presentation and apoptosis

2004 ◽  
Vol 76 (3) ◽  
pp. 519-527 ◽  
Author(s):  
Roberta O. Pinheiro ◽  
Eduardo F. Pinto ◽  
Alessandra B. Benedito ◽  
Ulisses G. Lopes ◽  
Bartira Rossi-Bergmann
Keyword(s):  
T Cell ◽  
Immune Responses ◽  
Antigen Presentation ◽  
T Cell Activation ◽  
Cell Activation ◽  
Leishmania Amazonensis ◽  
T Cell Anergy ◽  
Crude Antigen ◽  
Lymph Node Cells ◽  
Cell Anergy

Leishmania amazonensis is the main agent of diffuse cutaneous leishmaniasis, a disease associated with anergic immune responses. In this study we show that the crude antigen of Leishmania amazonensis (LaAg) but not L. braziliensis promastigotes (LbAg) contains substances that suppress mitogenic and spontaneous proliferative responses of T cells. The suppressive substances in LaAg are thermoresistant (100ºC/1h) and partially dependent on protease activity. T cell anergy was not due to a decreased production of growth factors as it was not reverted by addition of exogenous IL-2, IL-4, IFN-gamma or IL-12. LaAg did not inhibit anti-CD3-induced T cell activation, suggesting that anergy was due to a defect in antigen presentation. It was also not due to cell necrosis, but was accompanied by expressive DNA fragmentation in lymph node cells, indicative of apoptosis. Although pre-incubation of macrophages with LaAg prevented their capacity to present antigens, this effect was not due to apoptosis of the former. These results suggest that the T cell anergy found in diffuse leishmaniasis may be the result of parasite antigen-driven apoptosis of those cells following defective antigen presentation.

scholarly journals Cyclo-oxygenase type 2-dependent prostaglandin E2 secretion is involved in retrovirus-induced T-cell dysfunction in mice

2004 ◽  
Vol 384 (3) ◽  
pp. 469-476 ◽  
Author(s):  
Souad RAHMOUNI ◽  
Einar Martin AANDAHL ◽  
Btissam NAYJIB ◽  
Mustapha ZEDDOU ◽  
Sandra GIANNINI ◽  
...  
Keyword(s):  
T Cell ◽  
Prostaglandin E2 ◽  
T Cell Activation ◽  
Cell Activation ◽  
Lymphoproliferative Disease ◽  
Cell Dysfunction ◽  
T Cell Anergy ◽  
T Cell Dysfunction ◽  
Cell Anergy

MAIDS (murine AIDS) is caused by infection with the murine leukaemia retrovirus RadLV-Rs and is characterized by a severe immunodeficiency and T-cell anergy combined with a lymphoproliferative disease affecting both B- and T-cells. Hyperactivation of the cAMP-protein kinase A pathway is involved in the T-cell dysfunction of MAIDS and HIV by inhibiting T-cell activation through the T-cell receptor. In the present study, we show that MAIDS involves a strong and selective up-regulation of cyclo-oxygenase type 2 in the CD11b+ subpopulation of T- and B-cells of the lymph nodes, leading to increased levels of PGE2 (prostaglandin E2). PGE2 activates the cAMP pathway through G-protein-coupled receptors. Treatment with cyclo-oxygenase type 2 inhibitors reduces the level of PGE2 and thereby reverses the T-cell anergy, restores the T-cell immune function and ameliorates the lymphoproliferative disease.

scholarly journals PAG-Associated FynT Regulates Calcium Signaling and Promotes Anergy in T Lymphocytes

2007 ◽  
Vol 27 (5) ◽  
pp. 1960-1973 ◽  
Author(s):  
Dominique Davidson ◽  
Burkhart Schraven ◽  
André Veillette
Keyword(s):  
T Cells ◽  
T Cell ◽  
Tyrosine Phosphorylation ◽  
T Cell Activation ◽  
Protein Tyrosine Kinase ◽  
Cell Activation ◽  
T Cell Anergy ◽  
Cell Anergy ◽  
Anergic T Cells ◽  
Selective Enhancement

ABSTRACT Phosphoprotein associated with glycolipid-enriched membranes (PAG), also named Csk-binding protein (Cbp), is a transmembrane adaptor associated with lipid rafts. It is phosphorylated on multiple tyrosines located in the cytoplasmic domain. One tyrosine, tyrosine 314 (Y314) in the mouse, interacts with Csk, a protein tyrosine kinase that negatively regulates Src kinases. This interaction enables PAG to inhibit T-cell antigen receptor (TCR)-mediated T-cell activation. PAG also associates with the Src-related kinase FynT. Genetic studies indicated that FynT was required for PAG tyrosine phosphorylation and binding of PAG to Csk in T cells. Herein, we investigated the function and regulation of PAG-associated FynT. Our data showed that PAG was constitutively associated with FynT in unstimulated T cells and that this association was rapidly lost in response to TCR stimulation. Dissociation of the PAG-FynT complex preceded PAG dephosphorylation and PAG-Csk dissociation after TCR engagement. Interestingly, in anergic T cells, the association of PAG with FynT, but not Csk, was increased. Analyses of PAG mutants provided evidence that PAG interacted with FynT by way of tyrosines other than Y314. Enforced expression of a PAG variant interacting with FynT, but not Csk, caused a selective enhancement of TCR-triggered calcium fluxes in normal T cells. Furthermore, it promoted T-cell anergy. Both effects were absent in mice lacking FynT, implying that the effects were mediated by PAG-associated FynT. Hence, besides enabling PAG tyrosine phosphorylation and the PAG-Csk interaction, PAG-associated FynT can stimulate calcium signals and favor T-cell anergy. These data improve our comprehension of the function of PAG in T cells. They also further implicate FynT in T-cell anergy.

scholarly journals The PIKfyve Inhibitor Apilimod: A Double-Edged Sword against COVID-19

Cells ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 30
Author(s):  
Maksim V. Baranov ◽  
Frans Bianchi ◽  
Geert van den Bogaart
Keyword(s):  
Clinical Trials ◽  
T Cell ◽  
Immune Responses ◽  
Antigen Presentation ◽  
Host Cell ◽  
T Cell Activation ◽  
Cell Activation ◽  
Good Evidence ◽  
In Vitro Studies

The PIKfyve inhibitor apilimod is currently undergoing clinical trials for treatment of COVID-19. However, although apilimod might prevent viral invasion by inhibiting host cell proteases, the same proteases are critical for antigen presentation leading to T cell activation and there is good evidence from both in vitro studies and the clinic that apilimod blocks antiviral immune responses. We therefore warn that the immunosuppression observed in many COVID-19 patients might be aggravated by apilimod.

scholarly journals T cell anergy in COVID-19 reflects virus persistence and poor outcomes

2020 ◽  
Author(s):  
Kerstin Renner ◽  
Christine Mueller ◽  
Charlotte Tiefenboeck ◽  
Jan-Niklas Salewski ◽  
Frederike Winter ◽  
...  
Keyword(s):  
T Cell ◽  
T Cell Activation ◽  
Cell Activation ◽  
Severe Pneumonia ◽  
Cell Reactivity ◽  
Virus Persistence ◽  
T Cell Anergy ◽  
Cell Anergy ◽  
T Cell Reactivity ◽  
Poor Outcomes

Coronavirus disease 2019 (COVID-19) can lead to severe pneumonia and hyperinflammation. So far, insufficient or excessive T cell responses were described in patients. We applied novel approaches to analyze T cell reactivity and showed that T anergy is already present in non-ventilated COVID-19 patients, very pronounced in ventilated patients, strongly associated with virus persistence and reversible with clinical recovery. T cell activation was measured by downstream effects on responder cells like basophils, plasmacytoid dendritic cells, monocytes and neutrophils in whole blood and proved to be much more meaningful than classical readouts with PBMCs. Monocytes responded stronger in males than females and IL-2 partially reversed T cell anergy. Downstream markers of T cell anergy were also found in fresh blood samples of critically ill patients with severe T cell anergy. Based on our data we were able to develop a score to predict fatal outcomes and to identify patients that may benefit from strategies to overcome T cell anergy.

scholarly journals Thymic T cell anergy in autoimmune nonobese diabetic mice is mediated by deficient T cell receptor regulation of the pathway of p21ras activation.

1993 ◽  
Vol 177 (4) ◽  
pp. 1221-1226 ◽  
Author(s):  
M J Rapoport ◽  
A H Lazarus ◽  
A Jaramillo ◽  
E Speck ◽  
T L Delovitch
Keyword(s):  
T Cells ◽  
T Cell ◽  
Tyrosine Phosphorylation ◽  
T Cell Receptor ◽  
T Cell Activation ◽  
Cell Activation ◽  
Cell Receptor ◽  
T Cell Anergy ◽  
Nonobese Diabetic ◽  
Cell Anergy

Thymic T cell anergy, as manifested by thymocyte proliferative unresponsiveness to antigens expressed in the thymic environment, is commonly believed to mediate the acquisition of immunological self-tolerance. However, we previously found that thymic T cell anergy may lead to the breakdown of tolerance and predispose to autoimmunity in nonobese diabetic (NOD) mice. Here, we show that NOD thymic T cell anergy, as revealed by proliferative unresponsiveness in vitro after stimulation through the T cell receptor (TCR), is associated with defective TCR-mediated signal transduction along the PKC/p21ras/p42mapk pathway of T cell activation. PKC activity is reduced in NOD thymocytes. Activation of p21ras is deficient in quiescent and stimulated NOD T cells, and this is correlated with a significant reduction in the tyrosine phosphorylation of p42mapk, a serine/threonine kinase active downstream of p21ras. Treatment of NOD T cells with a phorbol ester not only enhances their p21ras activity and p42mapk tyrosine phosphorylation but also restores their proliferative responsiveness. Since p42mapk activity is required for progression through to S phase of the cell cycle, our data suggest that reduced tyrosine phosphorylation of p42mapk in stimulated NOD T cells may abrogate its activity and elicit the proliferative unresponsiveness of these cells.

Microglia induce myelin basic protein-specific T cell anergy or T cell activation, according to their state of activation

1999 ◽  
Vol 29 (10) ◽  
pp. 3063-3076 ◽  
Author(s):  
Malgosia K. Matyszak ◽  
Suzanne Denis-Donini ◽  
Stefania Citterio ◽  
Renato Longhi ◽  
Francesca Granucci ◽  
...  
Keyword(s):  
T Cell ◽  
Myelin Basic Protein ◽  
T Cell Activation ◽  
Cell Activation ◽  
Basic Protein ◽  
T Cell Anergy ◽  
Cell Anergy

scholarly journals T cell anergy in COVID-19 reflects virus persistence and poor outcomes

2020 ◽  
Author(s):  
Kerstin Renner ◽  
Christine Müller ◽  
Charlotte Tiefenböck ◽  
Jan-Niklas Salewski ◽  
Frederike Winter ◽  
...  
Keyword(s):  
T Cell ◽  
T Cell Activation ◽  
Cell Activation ◽  
Severe Pneumonia ◽  
Cell Reactivity ◽  
Virus Persistence ◽  
T Cell Anergy ◽  
Cell Anergy ◽  
T Cell Reactivity ◽  
Poor Outcomes

Abstract Coronavirus disease 2019 (COVID-19) can lead to severe pneumonia and hyperinflammation. So far, insufficient or excessive T cell responses were described in patients. We applied novel approaches to analyze T cell reactivity and showed that T anergy is already present in non-ventilated COVID-19 patients, very pronounced in ventilated patients, strongly associated with virus persistence and reversible with clinical recovery. T cell activation was measured by downstream effects on responder cells like basophils, plasmacytoid dendritic cells, monocytes and neutrophils in whole blood and proved to be much more meaningful than classical readouts with PBMCs. Monocytes responded stronger in males than females and IL-2 partially reversed T cell anergy. Downstream markers of T cell anergy were also found in fresh blood samples of critically ill patients with severe T cell anergy. Based on our data we were able to develop a score to predict fatal outcomes and to identify patients that may benefit from strategies to overcome T cell anergy.

scholarly journals Differences in TCR repertoire and T cell activation underlie the divergent outcomes of antitumor immune responses in tumor-eradicating versus tumor-progressing hosts

2021 ◽  
Vol 9 (1) ◽  
pp. e001615
Author(s):  
Rachel A Woolaver ◽  
Xiaoguang Wang ◽  
Alexandra L Krinsky ◽  
Brittany C Waschke ◽  
Samantha M Y Chen ◽  
...  
Keyword(s):  
T Cell ◽  
Mouse Model ◽  
Immune Responses ◽  
Single Cell ◽  
T Cell Activation ◽  
Antitumor Immunity ◽  
Cell Activation ◽  
Tcr Repertoire ◽  
Underlying Mechanisms ◽  
Personalized Cancer

BackgroundAntitumor immunity is highly heterogeneous between individuals; however, underlying mechanisms remain elusive, despite their potential to improve personalized cancer immunotherapy. Head and neck squamous cell carcinomas (HNSCCs) vary significantly in immune infiltration and therapeutic responses between patients, demanding a mouse model with appropriate heterogeneity to investigate mechanistic differences.MethodsWe developed a unique HNSCC mouse model to investigate underlying mechanisms of heterogeneous antitumor immunity. This model system may provide a better control for tumor-intrinsic and host-genetic variables, thereby uncovering the contribution of the adaptive immunity to tumor eradication. We employed single-cell T-cell receptor (TCR) sequencing coupled with single-cell RNA sequencing to identify the difference in TCR repertoire of CD8 tumor-infiltrating lymphocytes (TILs) and the unique activation states linked with different TCR clonotypes.ResultsWe discovered that genetically identical wild-type recipient mice responded heterogeneously to the same squamous cell carcinoma tumors orthotopically transplanted into the buccal mucosa. While tumors initially grew in 100% of recipients and most developed aggressive tumors, ~25% of recipients reproducibly eradicated tumors without intervention. Heterogeneous antitumor responses were dependent on CD8 T cells. Consistently, CD8 TILs in regressing tumors were significantly increased and more activated. Single-cell TCR-sequencing revealed that CD8 TILs from both growing and regressing tumors displayed evidence of clonal expansion compared with splenic controls. However, top TCR clonotypes and TCR specificity groups appear to be mutually exclusive between regressing and growing TILs. Furthermore, many TCRα/TCRβ sequences only occur in one recipient. By coupling single-cell transcriptomic analysis with unique TCR clonotypes, we found that top TCR clonotypes clustered in distinct activation states in regressing versus growing TILs. Intriguingly, the few TCR clonotypes shared between regressors and progressors differed greatly in their activation states, suggesting a more dominant influence from tumor microenvironment than TCR itself on T cell activation status.ConclusionsWe reveal that intrinsic differences in the TCR repertoire of TILs and their different transcriptional trajectories may underlie the heterogeneous antitumor immune responses in different hosts. We suggest that antitumor immune responses are highly individualized and different hosts employ different TCR specificities against the same tumors, which may have important implications for developing personalized cancer immunotherapy.

scholarly journals Immune Restoration Diseases Reflect Diverse Immunopathological Mechanisms

2009 ◽  
Vol 22 (4) ◽  
pp. 651-663 ◽  
Author(s):  
Patricia Price ◽  
David M. Murdoch ◽  
Upasna Agarwal ◽  
Sharon R. Lewin ◽  
Julian H. Elliott ◽  
...  
Keyword(s):  
T Cell ◽  
Immune Responses ◽  
T Cell Activation ◽  
Cell Activation ◽  
De Novo ◽  
Granulomatous Inflammation ◽  
T Cell Response ◽  
Immune Restoration ◽  
Immunological Parameters ◽  
Varicella Zoster

SUMMARY Up to one in four patients infected with human immunodeficiency virus type 1 and given antiretroviral therapy (ART) experiences inflammatory or cellular proliferative disease associated with a preexisting opportunistic infection, which may be subclinical. These immune restoration diseases (IRD) appear to result from the restoration of immunocompetence. IRD associated with intracellular pathogens are characterized by cellular immune responses and/or granulomatous inflammation. Mycobacterial and cryptococcal IRD are attributed to a pathological overproduction of Th1 cytokines. Clinicopathological characteristics of IRD associated with viral infections suggest different pathogenic mechanisms. For example, IRD associated with varicella-zoster virus or JC polyomavirus infection correlate with a CD8 T-cell response in the central nervous system. Exacerbations or de novo presentations of hepatitis associated with hepatitis C virus (HCV) infection following ART may also reflect restoration of pathogen-specific immune responses as titers of HCV-reactive antibodies rise in parallel with liver enzymes and plasma markers of T-cell activation. Correlations between immunological parameters assessed in longitudinal sample sets and clinical presentations are required to illuminate the diverse immunological scenarios described collectively as IRD. Here we present salient clinical features and review progress toward understanding their pathogeneses.

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