scholarly journals Activated T-effector seeds: cultivating atherosclerotic plaque through alternative activation

2019 ◽  
Vol 316 (6) ◽  
pp. H1354-H1365 ◽  
Author(s):  
Maria M. Xu ◽  
Patrick A. Murphy ◽  
Anthony T. Vella
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Cell Activation ◽  
Immune Cell ◽  
Behavior Pattern ◽  
Adaptive Immune System ◽  
Alternative Activation ◽  
Branch Points ◽  
Activated T Cells

Atherosclerosis is a chronic inflammatory pathology that precipitates substantial morbidity and mortality. Although initiated by physiological patterns of low and disturbed flow that differentially prime endothelial cells at sites of vessel branch points and curvature, the chronic, smoldering inflammation of atherosclerosis is accelerated by comorbidities involving inappropriate activation of the adaptive immune system, such as autoimmunity. The innate contributions to atherosclerosis, especially in the transition of monocyte to lipid-laden macrophage, are well established, but the mechanisms underpinning the infiltration, persistence, and effector dynamics of CD8 T cells in particular are not well understood. Adaptive immunity is centered on a classical cascade of antigen recognition and activation, costimulation, and effector cytokine secretion upon recall of antigen. However, chronic inflammation can generate alternative cues that supplant this behavior pattern and promote the retention and activation of peripherally activated T cells. Furthermore, the atherogenic foci that activated immune cell infiltrate are unique lipid-laden environments that offer a diverse array of stimuli, including those of survival, antigen hyporesponsiveness, and inflammatory cytokine expression. This review will focus on how known cardiovascular comorbidities may be influencing CD8 T-cell activation and how, once infiltrated within atherogenic foci, these T cells face a multitude of cues that skew the classical cascade of T-cell behavior, highlighting alternative modes of activation that may help contextualize associations of autoimmunity, viral infection, and immunotherapy with cardiovascular morbidity.

scholarly journals Annexin A5 is essential for PKCθ translocation during T-cell activation

2020 ◽  
Vol 295 (41) ◽  
pp. 14214-14221
Author(s):  
Zhaoqing Hu ◽  
Lin Li ◽  
Banghui Zhu ◽  
Yi Huang ◽  
Xinran Wang ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Cell Activation ◽  
Critical Role ◽  
Adaptive Immune System ◽  
Annexin A5 ◽  
Activated T Cells ◽  
Calcium Dependent

T-cell activation is a critical part of the adaptive immune system, enabling responses to foreign cells and external stimulus. In this process, T-cell antigen receptor (TCR) activation stimulates translocation of the downstream kinase PKCθ to the membrane, leading to NF-κB activation and thus transcription of relevant genes. However, the details of how PKCθ is recruited to the membrane remain enigmatic. It is known that annexin A5 (ANXA5), a calcium-dependent membrane-binding protein, has been reported to mediate PKCδ activation by interaction with PKCδ, a homologue of PKCθ, which implicates a potential role of ANXA5 involved in PKCθ signaling. Here we demonstrate that ANXA5 does play a critical role in the recruitment of PKCθ to the membrane during T-cell activation. ANXA5 knockout in Jurkat T cells substantially inhibited the membrane translocation of PKCθ upon TCR engagement and blocked the recruitment of CARMA1-BCL10-MALT1 signalosome, which provides a platform for the catalytic activation of IKKs and subsequent activation of canonical NF-κB signaling in activated T cells. As a result, NF-κB activation was impaired in ANXA5-KO T cells. T-cell activation was also suppressed by ANAX5 knockdown in primary T cells. These results demonstrated a novel role of ANXA5 in PKC translocation and PKC signaling during T-cell activation.

scholarly journals Functional Evaluation of Activation-dependent Alterations in the Sialoglycan Composition of T Cells

2013 ◽  
Vol 289 (3) ◽  
pp. 1564-1579 ◽  
Author(s):  
Yuko Naito-Matsui ◽  
Shuhei Takada ◽  
Yoshinobu Kano ◽  
Tomonori Iyoda ◽  
Manabu Sugai ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
B Cells ◽  
B Cell ◽  
T Cell Activation ◽  
Cell Activation ◽  
Immune Cell ◽  
Cell Interactions ◽  
Functional Evaluation ◽  
Activated T Cells

Sialic acids (Sias) are often conjugated to the termini of cellular glycans and are key mediators of cellular recognition. Sias are nine-carbon acidic sugars, and, in vertebrates, the major species are N-acetylneuraminic acid (Neu5Ac) and N-glycolylneuraminic acid (Neu5Gc), differing in structure at the C5 position. Previously, we described a positive feedback loop involving regulation of Neu5Gc expression in mouse B cells. In this context, Neu5Gc negatively regulated B-cell proliferation, and Neu5Gc expression was suppressed upon activation. Similarly, resting mouse T cells expressed principally Neu5Gc, and Neu5Ac was induced upon activation. In the present work, we used various probes to examine sialoglycan expression by activated T cells in terms of the Sia species expressed and the linkages of Sias to glycans. Upon T-cell activation, sialoglycan expression shifted from Neu5Gc to Neu5Ac, and the linkage shifted from α2,6 to α2,3. These changes altered the expression levels of sialic acid-binding immunoglobulin-like lectin (siglec) ligands. Expression of sialoadhesin and Siglec-F ligands increased, and that of CD22 ligands decreased. Neu5Gc exerted a negative effect on T-cell activation, both in terms of the proliferative response and in the context of activation marker expression. Suppression of Neu5Gc expression in mouse T and B cells prevented the development of nonspecific CD22-mediated T cell-B cell interactions. Our results suggest that an activation-dependent shift from Neu5Gc to Neu5Ac and replacement of α2,6 by α2,3 linkages may regulate immune cell interactions at several levels.

scholarly journals TCR Recognition of Peptide–MHC-I: Rule Makers and Breakers

2020 ◽  
Vol 22 (1) ◽  
pp. 68
Author(s):  
Christopher Szeto ◽  
Christian A. Lobos ◽  
Andrea T. Nguyen ◽  
Stephanie Gras
Keyword(s):  
Immune Response ◽  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Cell Activation ◽  
Adaptive Immune System ◽  
Human Leukocyte ◽  
Activated T Cells ◽  
Mhc I ◽  
Mhc Molecules

T cells are a critical part of the adaptive immune system that are able to distinguish between healthy and unhealthy cells. Upon recognition of protein fragments (peptides), activated T cells will contribute to the immune response and help clear infection. The major histocompatibility complex (MHC) molecules, or human leukocyte antigens (HLA) in humans, bind these peptides to present them to T cells that recognise them with their surface T cell receptors (TCR). This recognition event is the first step that leads to T cell activation, and in turn can dictate disease outcomes. The visualisation of TCR interaction with pMHC using structural biology has been crucial in understanding this key event, unravelling the parameters that drive this interaction and their impact on the immune response. The last five years has been the most productive within the field, wherein half of current unique TCR–pMHC-I structures to date were determined within this time. Here, we review the new insights learned from these recent TCR–pMHC-I structures and their impact on T cell activation.

scholarly journals Novel self-amplificatory loop between T cells and tenocytes as a driver of chronicity in tendon disease

2021 ◽  
pp. annrheumdis-2020-219335
Author(s):  
Emma Garcia-Melchor ◽  
Giacomo Cafaro ◽  
Lucy MacDonald ◽  
Lindsay A N Crowe ◽  
Shatakshi Sood ◽  
...  
Keyword(s):  
T Cells ◽  
Cell Migration ◽  
T Cell ◽  
Inflammatory Cytokines ◽  
T Cell Activation ◽  
Cell Activation ◽  
Conditioned Media ◽  
Tissue Remodelling ◽  
Activated T Cells ◽  
T Cell Migration

ObjectivesIncreasing evidence suggests that inflammatory mechanisms play a key role in chronic tendon disease. After observing T cell signatures in human tendinopathy, we explored the interaction between T cells and tendon stromal cells or tenocytes to define their functional contribution to tissue remodelling and inflammation amplification and hence disease perpetuation.MethodsT cells were quantified and characterised in healthy and tendinopathic tissues by flow cytometry (FACS), imaging mass cytometry (IMC) and single cell RNA-seq. Tenocyte activation induced by conditioned media from primary damaged tendon or interleukin-1β was evaluated by qPCR. The role of tenocytes in regulating T cell migration was interrogated in a standard transwell membrane system. T cell activation (cell surface markers by FACS and cytokine release by ELISA) and changes in gene expression in tenocytes (qPCR) were assessed in cocultures of T cells and explanted tenocytes.ResultsSignificant quantitative differences were observed in healthy compared with tendinopathic tissues. IMC showed T cells in close proximity to tenocytes, suggesting tenocyte–T cell interactions. On activation, tenocytes upregulated inflammatory cytokines, chemokines and adhesion molecules implicated in T cell recruitment and activation. Conditioned media from activated tenocytes induced T cell migration and coculture of tenocytes with T cells resulted in reciprocal activation of T cells. In turn, these activated T cells upregulated production of inflammatory mediators in tenocytes, while increasing the pathogenic collagen 3/collagen 1 ratio.ConclusionsInteraction between T cells and tenocytes induces the expression of inflammatory cytokines/chemokines in tenocytes, alters collagen composition favouring collagen 3 and self-amplifies T cell activation via an auto-regulatory feedback loop. Selectively targeting this adaptive/stromal interface may provide novel translational strategies in the management of human tendon disorders.

NFATc3 regulates the transcription of genes involved in T-cell activation and angiogenesis

Blood ◽  
2011 ◽  
Vol 118 (3) ◽  
pp. 795-803 ◽  
Author(s):  
Katia Urso ◽  
Arantzazu Alfranca ◽  
Sara Martínez-Martínez ◽  
Amelia Escolano ◽  
Inmaculada Ortega ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Cell Activation ◽  
Target Genes ◽  
Gene Knockout ◽  
Activated T Cells ◽  
Knock Down ◽  
And Function

Abstract The nuclear factor of activated T cells (NFAT) family of transcription factors plays important roles in many biologic processes, including the development and function of the immune and vascular systems. Cells usually express more than one NFAT member, raising the question of whether NFATs play overlapping roles or if each member has selective functions. Using mRNA knock-down, we show that NFATc3 is specifically required for IL2 and cyclooxygenase-2 (COX2) gene expression in transformed and primary T cells and for T-cell proliferation. We also show that NFATc3 regulates COX2 in endothelial cells, where it is required for COX2, dependent migration and angiogenesis in vivo. These results indicate that individual NFAT members mediate specific functions through the differential regulation of the transcription of target genes. These effects, observed on short-term suppression by mRNA knock-down, are likely to have been masked by compensatory effects in gene-knockout studies.

T cells: a dedicated effector kinase pathways for every trait?

2021 ◽  
Vol 478 (6) ◽  
pp. 1303-1307
Author(s):  
Kriti Bahl ◽  
Jeroen P. Roose
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Cell Activation ◽  
Cell Receptor ◽  
Spectrometric Analysis ◽  
Activated T Cells ◽  
Biological Responses ◽  
Extracellular Signal ◽  
Differentiation And Proliferation

Signaling pathways play critical roles in regulating the activation of T cells. Recognition of foreign peptide presented by MHC to the T cell receptor (TCR) triggers a signaling cascade of proximal kinases and adapter molecules that lead to the activation of Effector kinase pathways. These effector kinase pathways play pivotal roles in T cell activation, differentiation, and proliferation. RNA sequencing-based methods have provided insights into the gene expression programs that support the above-mentioned cell biological responses. The proteome is often overlooked. A recent study by Damasio et al. [Biochem. J. (2021) 478, 79–98. doi:10.1042/BCJ20200661] focuses on characterizing the effect of extracellular signal-regulated kinase (ERK) on the remodeling of the proteome of activated CD8+ T cells using Mass spectrometric analysis. Surprisingly, the Effector kinase ERK pathway is responsible for only a select proportion of the proteome that restructures during T cell activation. The primary targets of ERK signaling are transcription factors, cytokines, and cytokine receptors. In this commentary, we discuss the recent findings by Damasio et al. [Biochem. J. (2021) 478, 79–98. doi:10.1042/BCJ20200661] in the context of different Effector kinase pathways in activated T cells.

scholarly journals SLFN2 protection of tRNAs from stress-induced cleavage is essential for T cell–mediated immunity

Science ◽  
2021 ◽  
Vol 372 (6543) ◽  
pp. eaba4220 ◽  
Author(s):  
Tao Yue ◽  
Xiaoming Zhan ◽  
Duanwu Zhang ◽  
Ruchi Jain ◽  
Kuan-wen Wang ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Cell Activation ◽  
Interleukin 2 ◽  
Cell Receptor ◽  
Cell Mediated Immunity ◽  
Activated T Cells ◽  
Granule Formation

Reactive oxygen species (ROS) increase in activated T cells because of metabolic activity induced to support T cell proliferation and differentiation. We show that these ROS trigger an oxidative stress response that leads to translation repression. This response is countered by Schlafen 2 (SLFN2), which directly binds transfer RNAs (tRNAs) to protect them from cleavage by the ribonuclease angiogenin. T cell–specific SLFN2 deficiency results in the accumulation of tRNA fragments, which inhibit translation and promote stress-granule formation. Interleukin-2 receptor β (IL-2Rβ) and IL-2Rγ fail to be translationally up-regulated after T cell receptor stimulation, rendering SLFN2-deficient T cells insensitive to interleukin-2’s mitogenic effects. SLFN2 confers resistance against the ROS-mediated translation-inhibitory effects of oxidative stress normally induced by T cell activation, permitting the robust protein synthesis necessary for T cell expansion and immunity.

scholarly journals Extracellular signal-regulated kinase (ERK) pathway control of CD8+ T cell differentiation

2020 ◽  
Author(s):  
Marcos P. Damasio ◽  
Julia M. Marchingo ◽  
Laura Spinelli ◽  
Doreen A. Cantrell ◽  
Andrew J.M. Howden
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Cell Activation ◽  
Antigen Receptor ◽  
T Cell Differentiation ◽  
Signalling Pathways ◽  
Activated T Cells ◽  
Transcriptional Reprogramming ◽  
Extracellular Signal

SummaryThe integration of multiple signalling pathways that co-ordinate T cell metabolism and transcriptional reprogramming is required to drive T cell differentiation and proliferation. One key T cell signalling module is mediated by extracellular signal-regulated kinases (ERKs) which are activated in response to antigen receptor engagement. The activity of ERKs is often used to report antigen receptor occupancy but the full details of how ERKs control T cell activation is not understood. Accordingly, we have used mass spectrometry to explore how ERK signalling pathways control antigen receptor driven proteome restructuring in CD8 + T cells to gain insights about the biological processes controlled by ERKs in primary lymphocytes. Quantitative analysis of >8000 proteins identified only 900 ERK regulated proteins in activated CD8+ T cells. The data identify both positive and negative regulatory roles for ERKs during T cell activation and reveal that ERK signalling primarily controls the repertoire of transcription factors, cytokines and cytokine receptors expressed by activated T cells. The ERKs thus drive the transcriptional reprogramming of activated T cells and the ability of T cells to communicate with external immune cues.

scholarly journals Distinct cellular immune profiles in the airways and blood of critically ill patients with COVID-19

2020 ◽  
Author(s):  
Anno Saris ◽  
Tom D.Y. Reijnders ◽  
Esther J. Nossent ◽  
Alex R. Schuurman ◽  
Jan Verhoeff ◽  
...  
Keyword(s):  
Immune Response ◽  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Peripheral Blood ◽  
Cell Activation ◽  
Effector Memory ◽  
Activated T Cells ◽  
Immune Profile ◽  
Prolonged Icu Stay

AbstractOur understanding of the coronavirus disease-19 (COVID-19) immune response is almost exclusively derived from studies that examined blood. To gain insight in the pulmonary immune response we analysed BALF samples and paired blood samples from 17 severe COVID-19 patients. Macrophages and T cells were the most abundant cells in BALF. In the lungs, both CD4 and CD8 T cells were predominantly effector memory cells and expressed higher levels of the exhaustion marker PD-1 than in peripheral blood. Prolonged ICU stay associated with a reduced proportion of activated T cells in peripheral blood and even more so in BALF. T cell activation in blood, but not in BALF, was higher in fatal COVID-19 cases. Increased levels of inflammatory mediators were more pronounced in BALF than in plasma. In conclusion, the bronchoalveolar immune response in COVID-19 has a unique local profile that strongly differs from the immune profile in peripheral blood.SummaryThe bronchoalveolar immune response in severe COVID-19 strongly differs from the peripheral blood immune profile. Fatal COVID-19 associated with T cell activation blood, but not in BALF.

scholarly journals A novel form of immune signaling revealed by transmission of the inflammatory mediator serotonin between dendritic cells and T cells

Blood ◽  
2006 ◽  
Vol 107 (3) ◽  
pp. 1010-1017 ◽  
Author(s):  
Peta J. O'Connell ◽  
Xiangbin Wang ◽  
Matilde Leon-Ponte ◽  
Corrie Griffiths ◽  
Sandeep C. Pingle ◽  
...  
Keyword(s):  
T Cells ◽  
Dendritic Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Cell Activation ◽  
Activated T Cells ◽  
Immune Synapse ◽  
Cell Proliferation And Differentiation ◽  
Proliferation And Differentiation ◽  
5 Ht Uptake

AbstractAdaptive immunity is triggered at the immune synapse, where peptide-major histocompatibility complexes and costimulatory molecules expressed by dendritic cells (DCs) are physically presented to T cells. Here we describe transmission of the inflammatory monoamine serotonin (5-hydroxytryptamine [5-HT]) between these cells. DCs take up 5-HT from the microenvironment and from activated T cells (that synthesize 5-HT) and this uptake is inhibited by the antidepressant, fluoxetine. Expression of 5-HT transporters (SERTs) is regulated by DC maturation, exposure to microbial stimuli, and physical interactions with T cells. Significantly, 5-HT sequestered by DCs is stored within LAMP-1+ vesicles and subsequently released via Ca2+-dependent exocytosis, which was confirmed by amperometric recordings. In turn, extracellular 5-HT can reduce T-cell levels of cAMP, a modulator of T-cell activation. Thus, through the uptake of 5-HT at sites of inflammation, and from activated T cells, DCs may shuttle 5-HT to naive T cells and thereby modulate T-cell proliferation and differentiation. These data constitute the first direct measurement of triggered exocytosis by DCs and reveal a new and rapid type of signaling that may be optimized by the intimate synaptic environment between DCs and T cells. Moreover, these results highlight an important role for 5-HT signaling in immune function and the potential consequences of commonly used drugs that target 5-HT uptake and release.

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