bluuebunny/crossref_metadata_2025_split huggingface dataset:
pMHC ligand anchored on a plastic surface via a 61 nm flexible poly(ethylene glycol) linker triggers the TCR: implications for the mechanism of TCR signal initiation (35.18)
Authors: Ma Zhengyu , Janmey Paul , Finkel Terri H 
Published: January 2023

Abstract
A critical step in the immune response is signal initiation from the T cell antigen receptor (TCR) by its ligand, peptide antigen presented by the major histocompatibility complex (pMHC). How TCR is triggered by ligand binding is still unclear. An interesting aspect of the puzzle is the sharp contrast between the inability of soluble pMHC to trigger TCR and the high triggering efficiency of surface-anchored pMHC. Here, we investigate the boundary between soluble and surface-anchored pMHC by anchoring pMHCs on plastic surfaces via poly(ethylene glycol) (PEG) linkers of varying length. We found that pMHCs anchored on the surface via a 61 nm linker trigger TCR as efficiently as a much shorter 5.6 nm linker. The lack of negative impact on TCR triggering by the long linker does not support the kinetic segregation model of TCR triggering, in which the critical factor is the shortness of the pMHC-TCR bridge between the membranes of T cell and antigen presenting cell (APC). Our result supports the idea that TCR triggering does not require receptor cross-linking, since the length of the linker far exceeds the distance required for two pMHC molecules to cross-link the TCR. Furthermore, this result is consistent with the receptor deformation model - a long linker may be tolerated as long as the T cell and APC membranes detach to a distance greater than the length of the pMHC-TCR bridge, such that mechanical force can still be applied to the TCR.
Work supported by NIH R21 AI078387, Joseph L. Hollander Chair, and Joseph Stokes Jr. Res. Inst.
T cell raft clustering during T cell surveying of APCs requires CD28 (35.2)
Authors: Van Komen Jeffrey S , Mishra Sudha , Byrum Jennifer , Rodgers William 
Published: January 2023

Abstract
T cell activation requires the orchestrated restructuring of its plasma membrane rafts to form the immunological synapse (IS). Our published data show an antigen (Ag)-independent membrane raft cluster that concentrates the TCR and CD4 at the site of Ag presentation before TCR triggering. We term this event raft clustering during surveying (RaCS). However, the mechanisms by which RaCS occurs is unknown. Our recent experiments show RaCS is initiated by CD28-dependent mechanisms. For example, RaCS was not detected in CD28-deficent T cells. Experiments with CD28-deficient T cells transduced with genes encoding mutated CD28 molecules showed that both the PI3K- and Lck-binding sites of CD28 are necessary for RaCS. These results in conjunction with imaging experiments using PP2 or wortmannin treated T cells suggest that PI3K- and Lck-association with CD28 is required for RaCS. We also observed that RaCS is inhibited in anergic T cells, whereas, SLE model mice exhibited increased RaCS. Collectively, our results show that actin-dependent RaCS at the APC is one of the earliest events in T cell activation, and provides a mechanism for tuning downstream Ag-dependent signaling events. Future experiments will determine the mechanism by which CD28 activation signals cluster the T cell rafts, and the effect of RaCS on interactions within the TCR complex.
This work is supported by the American Cancer Society (PF-08-178-01-LIB to JVK) and the NIH (P50 RR015577 and R01 GM070001 to WR).
Inhibition of activation-induced T cell death by AIP2-mediated ubiquitination of EGR2 (35.20)
Authors: Fang Deyu , Chen An , Lee Sang-Myeong 
Published: January 2023

Abstract
E3 ubiquitin ligases, which target specific molecules for proteolytic destruction, have emerged as key regulators of immune functions. Several E3 ubiquitin ligases, including c-Cbl, Cbl-b, GRAIL, Itch, and Nedd4, have been shown to negatively regulate T-cell activation. Here we report that the HECT-type E3 ligase, AIP2, positively regulates T-cell activation. Ectopic expression of AIP2 in mouse primary T cells enhances their proliferation and IL-2 production by suppressing apoptosis of T cells. AIP2 interacts with and promotes ubiquitin-mediated degradation of EGR2, a zinc finger transcription factor that has been found to regulate Fas ligand (FasL) expression during activation-induced T cell death. Suppression of AIP2 expression by small RNA interference upregulates EGR2 and FasL expression and enhances the apoptosis of T cells. Therefore, AIP2 regulates activation-induced T cell death by suppressing EGR2-mediated FasL expression via the ubiquitin pathway.
Differential TCR signal transduction pathways involved in high and low avidity CD8+ T-cell responsiveness (35.26)
Authors: Sharma Sharad K , Alexander-Miller Martha A 
Published: January 2023

Abstract
CTLs that display high functional avidity are known to be optimal for pathogen clearance. However, the molecular mechanism that allows high avidity CTLs to respond at very low levels of peptide antigen remains to be elucidated. To investigate this question, we compared TCR signal transduction events in high and low avidity CD8+ T-cells generated from OT-I TCR transgenic mice. Upon stimulation with APCs preloaded with a range of Ova257-264 peptide concentrations (10^-6, 10^-9 and 10^-12 M), we found that high avidity CD8+ T-cells induced higher levels of MAPK ERK-1/2 phosphorylation as well as higher levels of the dephosphorylated form of NFAT at each peptide concentration used for stimulation. We next determined whether the observed divergence in NFAT activation was reflected in differences in calcium mobilization. We found efficient mobilization of Ca2+ in high avidity cells even when the lowest concentration of peptide was used for stimulation, a level of peptide at which no increase in calcium was observed in low avidity cells. The decreased peptide requirement for calcium mobilization in high avidity cells correlated with a decreased peptide requirement for ZAP-70 activation and CD3ζ phosphorylation, the latter of which was higher and prolonged in high versus low avidity cells. Thus the functional avidity of the CD8+ effector cells studies here is controlled by differential regulation of the most membrane proximal event, phosphorylation of CD3ζ. Studies are currently underway to determine the mechanism by which high avidity cells acheive CD3ζ phosphorylation at limiting peptide levels.
Calculations show that T cell antigen discrimination requires multiple localized binding events (35.3)
Authors: Dushek Omer , Aleksic Milos , van der Merwe Anton , Coombs Daniel 
Published: January 2023

Abstract
T cells of the adaptive immune system rapidly scan the surface of antigen-presenting-cells (APC) for foreign material, in the form of peptide-MHC, using their T cell receptors (TCR). T cell activation via TCR-pMHC binding is extremely sensitive (a single presented pMHC can elicit a transient response), specific (a single amino acid substitution on a presented peptide can dramatically alter the response), and the decision to respond (e.g. by forming an immune synapse) occurs rapidly. Mathematical modeling based on statistical distributions reveals that pMHC must be repeatedly sampled (by binding TCR) in order for the T cell to make the decision to respond (or not) reliably. We find that TCR clustering and coreceptors act to immobilize pMHC which ensures that multiple binding events arise from a given pMHC. Functional assays of 1G4 T cells binding to a panel of 17 altered-peptide-ligands (NY-ESO) are used to support predictions from the model. We propose that sensitive, specific, and rapid antigen discrimination that is reliable can take place between a single TCR/pMHC.
Comparison of Dexamethasone and Cyclosporine to selective protein Kinase C-theta inhibitor effects on blood IL-2 production and T cell activation (35.32)
Authors: Ho Melisa W.-Y. , Deng Bijia , Benoit Stephen , Chen Joan , Wang Daniel , Boschelli Diane , Goldman Samuel , Kasaian Marion , Chaudhary Divya 
Published: January 2023

Abstract
Protein kinase C-theta (PKCθ) is critical in T cell IL-2 production upon TCR stimulation, making PKCθ an attractive drug target for inflammatory diseases. Our goal was to compare the effects of PKCθ selective blockade to alternative immune modulators dexamethasone (Dex) and cyclosporine A (CsA). Compound A, a selective PKCθ inhibitor, was evaluated on T cell responses following co-stimulation in vitro. With pre-activated CD4+ T cells, both Compound A and CsA reduced IL-2 production with comparable potency. However, CsA inhibited T cell proliferation with 10 fold higher potency than Compound A. Dex was the least potent on T cells but was effective in blocking IL-2 production in human whole blood. Next we examined whether exposure to Compound A or CsA in a primary activation would affect the ability of T cells to respond to secondary TCR stimulation. Both Compound A and CsA reduced T cell proliferation upon re-stimulation. Exogenous IL-2 restored the proliferation for Compound A exposed T cells, but not for CsA exposed T cells. We confirmed that Compound A-treated T cells had higher CD25 expression relative to those treated with CsA, accounting for their greater IL-2 responsiveness. Taken together, these findings indicate that targeting PKCθ impairs T cell IL-2 production, but not IL-2 responsiveness, suggesting that this inhibitor may selectively modulate T cell responsiveness under specific activation conditions.
Increased body temperature induces lymphocyte lipid raft aggregation (35.34)
Authors: Mace Thomas A , Kilpatrick Casey , Zynda Evan , Repasky Elizabeth 
Published: January 2023

Abstract
Previous recent data reveal that mild heating in vitro of CD4+ and CD8+ T cells (purified from murine splenocytes) at 39.5°C induces the aggregation of lipid rafts; approximately 70% of lymphocytes express aggregated lipid rafts compared to only 20% of cells maintained at 37oC as judged by the distribution of the lipid raft marker, fluorescently labeled GM1. Further, we found that the fluidity of the T cell plasma membrane, as measured by fluorescence anisotropy of TMA-DPH, increases when the temperature is raised from 37° to 39.5°C. Based on these in vitro results, we hypothesized that a physiologically relevant increase in body temperature results in an increase in lipid raft aggregation in T cells in situ. We administered whole body hyperthermia (WBH) to raise the temperature of mice to 39.5°C for 6 hours and immediately harvested and fixed cells from spleen and lymph nodes. Utilizing Imagestream flow cytometry, we observed a 3 fold increase in the number of CD8+ T cells with lipid raft aggregates isolated from WBH mice compared to T cells isolated from normothermic control mice. Lymphocytes from spleen and lymph nodes responded similarly to WBH. Overall, these findings may help to understand the role of physiological temperature shifts (e.g., during febrile episodes and inflammation) on costimulation and lymphocyte activation potential.
Supported by NIH P01 CA94045 and RO1 CA71599
Regulation of Tim-1 signaling and localization in T cell activation (35.35)
Authors: Lin Jean Y , Delmastro Meghan M , Kane Lawrence P 
Published: January 2023

Abstract
T cell immunoglobulin and mucin domain 1 (Tim-1) can modulate CD4+ T helper responses. However, the precise mechanisms by which Tim-1 regulates T cell function remain relatively undefined. Work in this study focuses on identifying downstream targets of Tim-1 signaling as well as understanding Tim-1 localization during T cell activation. The consequences of Tim-1 interaction with antibodies or its ligand phosphatidylserine (PS) were explored by luciferase assays to determine levels of NFAT/AP-1 or by Western blotting for Tim-1 induced phosphorylation. Confocal microscopy was used to visualize Tim-1 localization on T cells after transfection of tagged forms of Tim-1 into D10 cells and incubation with antigen loaded antigen presenting cells (APCs). Results/Conclusions: Agonistic Tim-1 antibodies induce a previously unrecognized phosphorylated substrate, which we are currently attempting to identify. No induction of NFAT/AP-1 after interaction with PS expression apoptotic cells was apparent. Tim-1 localizes away from the immunological synapse after T cell activation. Better understanding of Tim-1 interactions with its antibodies, ligands, and APCs will allow for better understanding Tim-1 activation.
NCI and NIAID
Beta-catenin negatively regulates peripheral T cell activation (35.36)
Authors: Driessens Gregory , Gajewski Thomas 
Published: January 2023

Abstract
β-catenin signaling has been shown to play a role in T cell development. However, the function of β-catenin in peripheral T cell regulation is not understood. Activation of T cells via TCR/CD28 ligation resulted in low-level stabilization of β-catenin which was augmented with proteasome inhibition. To determine the consequences of increased β-catenin expression, CAR Tg T cells were transduced with an adenoviral vector encoding a non-degradable β-catenin, which inhibited proliferation and cytokine secretion. Experiments were performed to determine the mechanism of this inhibition. Decreased IL-2 production was confirmed at the mRNA level, and surface expression of TCR and CD28 were not altered. IL-2 production was rescued with PMA+Ionomycin, arguing for a defect in proximal TCR signaling. TCR-induced phosphorylation of Lck, LAT, Akt, and ERK were intact in β-catenin-expressing T cells. However, phosphorylation of PLC-γ1 was significantly reduced, as was Ca++ flux. Conversely, deletion of the β-catenin gene from primary T cells using CAR Tg conditional knockout mice and a Cre-adenovirus caused augmented cytokine production and proliferation. Our results suggest that β-catenin negatively regulates TCR-mediated activation or peripheral T cells via a novel mechanism.
SHP-1 regulation of in vivo CD8 T cell responses (35.43)
Authors: Fowler Carla , Pao Lily , Schietinger Andrea , Tan Xiaoxia , Blattman Joseph , Greenberg Philip 
Published: January 2023

Abstract
OBJECTIVE: Determine the cell-intrinsic effect of SHP-1 deficiency on the primary response and memory formation of CD8 T cells following viral infection.
METHODS: Conditional deletion of SHP-1 in peripheral T cells was achieved by crossing mice transgenic for Cre-recombinase expressed under the distal-LCK promoter to mice bearing a floxed SHP-1 gene. SHP-1+/+, SHP-1+/-, or SHP-1-/- P14 transgenic CD8 T cells specific for LCMVGP33 were adoptively transferred into wild-type (WT) hosts, infected with LCMV, and analyzed.
RESULTS: At the peak of the primary response, SHP-1-/- CD8 T cells showed 2-3 fold greater expansion than WT cells. The increased magnitude of the peak response reflected mostly increased numbers of cells expressing a terminally differentiated surface phenotype. Consistent with this phenotypic data, SHP-1-/- CD8 T cells underwent a larger contraction following infection, and formed long-lived memory populations of similar magnitude to WT CD8 T cells.
CONCLUSIONS: SHP-1 regulates TCR signal strength in vivo and this regulation impacts both the magnitude of peak expansion as well as the number of the peak effector cells that have differentiated towards a short-lived fate. The formation of long-lived memory populations, however, appears to be regulated independently of SHP-1.
SUPPORT: ARCS Foundation, Poncin Fellowship, Bill and Melinda Gates Foundation, NCI, and Leukemia and Lymphoma Society.
Novel function of perforin in regulating CD4+ T cell activation by affecting calcium signaling (35.7)
Authors: sun bing , bi enguang 
Published: January 2023

Abstract
Perforin is a pore forming protein engaged mainly in mediating target-cell death and is employed by cytotoxic T lymphocytes (CTLs) and natural killer (NK) cells. However, whether it also plays a role in conventional CD4+ T cell function remains unclear. Here we report that in perforin-deficient(PKO) mice, CD4+ T cells are hyperproliferative in response to TCR stimulation. This feature of activated CD4+ T cells is accompanied by an enhancement both in cell division and in IL-2 secretion. The perforin deficiency does not appear to influence T cell development in thymus and lymph node. In vivo, perforin deficiency results in increased antigen-specific T cell proliferation and antibody production. Furthermore, PKO mice appear more susceptible to experimental autoimmune uveitis. Examination of the mechanisms involved demonstrate that in PKO CD4+ T cells TCR stimulation increases intracellular calcium flux and subsequently enhances activation of transcription factor NF-AT1. Our results indicate that perforin plays a negative role in regulating CD4+ T cell activation and immune response by affecting TCR-dependent Ca2+ signaling.
GPR34 is not required for mast cell degranulation induced by IgE or lysophosphatidyl-L-serine (36.1)
Authors: Vissinga Christine , Hensley Kelly , Kirchner Jacqueline 
Published: January 2023

Abstract
Mast cells play an important role in allergic inflammation. Upon activation by cross-linking of FcεRI, they rapidly release granule-associated chemical mediators and secrete cytokines, fatty acids and lipids which mediate allergic inflammation.
GPR34 is a GPCR expressed on mast cells and has been proposed to be a receptor for lysophosphatidylserine (lysoPS), a phospholipid derivative which can potentiate antigen-induced mast cell degranulation (BBRC 341: 1078, 2006). To determine if GPR34 is involved in mast cell response, we generated GPR34-/- mice and evaluated mast cell function in vitro and in vivo. Bone marrow-derived mast cells from GPR34+/+ and GPR34-/- mice exhibited similar responses, as measured by beta-hexosaminidase release, to IgE cross-linking or lysoPS stimulation. We evaluated the role of GPR34 in vivo using a passive cutaneous anaphylaxis model induced by crosslinking of FcεRI on mast cells. Mast cells in GPR34+/+ and GPR34-/- mice were activated by SC injection of anti-DNP IgE mAb followed by IV administration of DNP-BSA and Evans blue dye 24 hours later. Activation resulted in vascular permeability which was measured as the amount of dye influx. In this model, the mast cell response was unaffected by GPR34 gene deficiency.
Together, our results indicate that GPR34 is not required for the mast cell response to IgE crosslinking in vitro or in vivo and that GPR34 is not a receptor for lysoPS.
Receptor for advanced glycation end products is required for normal T cell activation and development of T cell induced lung inflammation (36.10)
Authors: Akirav Eitan M , Henegariu Octavian , Clynes Raphael , Schmidt Ann Marie , Herold Kevan C 
Published: January 2023

Abstract
We have shown that the receptor for advanced glycation endproducts (RAGE) is required for normal T cell activation and differentiation into Th1 cells, since RAGE-/- T cells show reduced proliferation and IFNγ expression after activation with alloantigens. Here, we examined T cell activation in RAGE-/- and OT-II.RAGE-/- mice in a model of T cell induced asthma. Intranasal OVA challenge of RAGE-/- mice resulted in reduced T cell activation as measured by increased CD62L expression, decreased CD69 expression, and reduced IL5 production. Cellular infiltrates in the lungs of OVA immunized RAGE-/- mice were reduced when compared with WT mice. Intranasal OVA challenge of OT-II mice induced a robust T cell infiltration of the lung, which was reduced in OT-II.RAGE-/- mice. Moreover, cells from mediastinal lymph nodes of OT-II.RAGE-/- mice showed reduced IL2, IL5, IL10, IL12, and IFN? production. Interestingly, purified RAGE-/- T cells showed lower basal levels of Ca2+ flux when compared with WT cells. These levels were not corrected in response to αCD3 stimulation. Reduced Ca2+ flux was associated with reduced expression of the transcription factor T-bet but with no change in GATA-3 expression in RAGE-/- T cells. In summary, these results reveal an unexpected defect in Ca2+ flux of RAGE deficient T cells under basal and activated conditions and reduced T cell activation in OVA-induced asthma, suggesting a novel role for RAGE in T cell signaling.
Using neurolinguistic-programming as an alternative treatment for allergic rhinitis (36.3)
Authors: Cervantes-Trujano Edgar , Rodriguez-Flores Azucena , Pérez-Perrusquia Marisol , Ramos-Rosales Cintia , Montiel-cortes Miguel , Estrada-Parra Sergio 
Published: January 2023

Abstract
The aim of this study is known as through the conceptual change of health status through neurolinguistics programming (NLP) can modify some mediators such as IgE, cortisol and lymphoid cells.
Material and Methods:
We performed a clinical trial, double-blind, placebo controlled and randomized 18 patients with AR with positive skin tests to aeroallergens. The control group (A) received a placebo of NLP more allergen-specific mixture by sublingual route, by period of 6 months. The experimental group (B) treated with NLP plus placebo mixture of allergens. All patients underwent the following assessments at baseline, three and six months after treatment: seric cortisol and total IgE, determination of lymphocyte populations and subpopulations and eosinophils in peripheral blood by flow cytometry.
Results
The patients were allergic to dust mites, pollens, animals, fungi. All patients had eosinophilia and increased serum IgE, decreased levels of CD4 + CD25 + cells. After 6 months of treatment, levels of IgE and cortisol were not changed, the eosinophilia decreased to normal values in both study groups and levels of CD4+ CD25+ cells increased with respect to its initial values with a statistically significant difference (p = 0.008).
Conclusions
Both treatments changed the status of patients with AR moderate persistent to AR mild intermittent and mild persistent, which shows a better control of the disease.
A Putative Immunoregulatory role for TSLP on CD4+ T cells (36.4)
Authors: de Souza Anjali J , Ziegler Steven 
Published: January 2023

Abstract
TSLP is primarily an epithelial cell derived cytokine that has been implicated in promoting Th-2 cytokine mediated inflammation at mucosal sites. The TSLP receptor is expressed on a variety of cell types including B cells, monocytes, dendritic cells and mast cells.
We have shown earlier that activated CD4+ T cells can also respond to TSLP, express the TSLP receptor and induce IL-4 expression. In this study we have further probed, the effects of TSLP on differentiation and function of other helper T cell lineages. Our data indicate that naive murine CD4+ T cells upon primary activation through the TCR coupled with either TSLP alone or in conjunction with TGF-beta can promote the differentiation and expansion of inducible regulatory T cells (iTregs) indicated by an increased population of FOXP3+ cells and in a manner that requires the TSLP receptor. When added to a cytokine milieu consisting of TGF-β and IL-6 alone or in combination with IL-21 which are known inducers of Th17 differentiation, TSLP downregulates IL-17 production. These data indicate that TSLP can directly influence differentiation of CD4 T cell lineages depending on the cytokine milieu and suggests an immune-regulatory role in disease. Future work is directed at understanding the mechanisms by which TSLP mediates it's effects on T cells and its application in vivo in promoting tolerance and regulating immune responses in allergic and autoimmune diseases.