bluuebunny/crossref_metadata_2025_split huggingface dataset:
Identification of MHC Class II-Restricted Peptide Ligands, Including a Glutamic Acid Decarboxylase 65 Sequence, that Stimulate Diabetogenic T Cells from Transgenic BDC2.5 Nonobese Diabetic Mice
Authors: Judkowski Valeria , Pinilla Clemencia , Schroder Kim , Tucker Lee , Sarvetnick Nora , Wilson Darcy B. 
Published: April 2014

Abstract
Nonobese diabetic (NOD) mice spontaneously develop insulitis and destruction of pancreatic islet β cells similar to type 1 diabetes mellitis in humans. Insulitis also occurs in the BDC2.5 TCR transgenic line of NOD mice that express the rearranged TCR α- and β-chain genes of a diabetogenic NOD CD4 T cell clone. When activated with syngeneic islet cells in culture, BDC2.5 T cells adoptively transfer disease to NOD recipients, but the identity of the islet cell Ag responsible for pathogenicity is not known. To characterize the autoantigen(s) involved, BDC2.5 T cells were used to screen a combinatorial peptide library arranged in a positional scanning format. We identified more than 100 decapeptides that stimulate these T cells at nanomolar concentrations; they are then capable of transferring disease to NOD-scid mice. Surprisingly, some of the peptides include sequences similar (8 of 10 residues) to those found within the 528–539 fragment of glutamic acid decarboxylase 65. Although this 12-mer glutamic acid decarboxylase 65 fragment is only slightly stimulatory for BDC2.5 T cells (EC50 &gt; 100 μM), a larger 16-mer fragment, 526–541, shows activity in the low micromolar range (EC50 = 2.3 μM). Finally, T cells from prediabetic NOD mice respond spontaneously to these peptide analogs in culture; this finding validates them as being related to a critical autoantigen involved in the etiology of spontaneous diabetes and indicates that their further characterization is important for a better understanding of underlying disease mechanisms.
The Serine/Threonine Phosphatase, PP2A: Endogenous Regulator of Inflammatory Cell Signaling
Authors: Shanley Thomas P. , Vasi Niti , Denenberg Alvin , Wong Hector R. 
Published: April 2014

Abstract
We have investigated the regulation of kinases and phosphatases in early gene activation in monocytes because these cells are implicated in the pathogenesis of acute inflammatory states, such as sepsis and acute lung injury. One early gene up-regulated by endotoxin is c-Jun, a member of the activating protein (AP) family. C-Jun is phosphorylated by c-Jun N-terminal kinase (JNK) and associates with c-Fos to form the AP-1 transcriptional activation complex that can drive cytokine expression. Inhibition of the serine/threonine phosphatase, PP2-A, with okadaic acid resulted in a significant increase in JNK activity. This finding was associated with increased phosphorylation of c-Jun, AP-1 transcriptional activity, and IL-1β expression. Activation of PP2A inhibited JNK activity and JNK coprecipitated with the regulatory subunit, PP2A-Aα, supporting the conclusion that PP2A is a key regulator of JNK in the context of an inflammatory stimulus.
Chemokine Receptor Expression and Function in CD4+ T Lymphocytes with Regulatory Activity
Authors: Sebastiani Silvia , Allavena Paola , Albanesi Cristina , Nasorri Francesca , Bianchi Giancarlo , Traidl Claudia , Sozzani Silvano , Girolomoni Giampiero , Cavani Andrea 
Published: April 2014

Abstract
We have investigated the chemokine receptor expression and migratory behavior of a new subset of nickel-specific skin-homing regulatory CD4+ T cells (ThIL-10) releasing high levels of IL-10, low IFN-γ, and undetectable IL-4. These cells inhibit in a IL-10-dependent manner the capacity of dendritic cells to activate nickel-specific Tc1 and Th1 lymphocytes. RNase protection assay and FACS analysis revealed the expression of a vast repertoire of chemokine receptors on resting ThIL-10, including the Th1-associated CXCR3 and CCR5, and the Th2-associated CCR3, CCR4, and CCR8, the latter at higher levels compared with Th2 cells. The most active chemokines for resting ThIL-10, in terms of calcium mobilization and in vitro migration, were in order of potency: CCL2 (monocyte chemoattractant protein-1, CCR2 ligand), CCL4 (macrophage-inflammatory protein-1β, CCR5 ligand), CCL3 (macrophage-inflammatory protein-1α, CCR1/5 ligand), CCL17 (thymus and activation-regulated chemokine, CCR4 ligand), CCL1 (I-309, CCR8 ligand), CXCL12 (stromal-derived factor-1, CXCR4), and CCL11 (eotaxin, CCR3 ligand). Consistent with receptor expression down-regulation, activated ThIL-10 exhibited a reduced or absent response to most chemokines, but retained a significant migratory capacity to I-309, monocyte chemoattractant protein-1, and thymus and activation-regulated chemokine. I-309, which was ineffective on Th1 lymphocytes, attracted more efficiently ThIL-10 than Th2 cells. I-309 and CCR8 mRNAs were not detected in unaffected skin and were up-regulated at the skin site of nickel-allergic reaction, with an earlier expression kinetics compared with IL-10 and IL-4. Results indicate that skin-homing regulatory ThIL-10 lymphocytes coexpress functional Th1- and Th2-associated chemokine receptors, and that CCR8/I-309-driven recruitment of both resting and activated ThIL-10 cells may be critically involved in the regulation of Th1-mediated skin allergic disorders.
Cutting Edge: Granzyme B Proteolysis of a Neuronal Glutamate Receptor Generates an Autoantigen and Is Modulated by Glycosylation
Authors: Gahring Lorise C. , Carlson Noel G. , Meyer Erin L. , Rogers Scott W. 
Published: April 2014

Abstract
Autoimmune processes are initiated when tolerance to self-proteins fails to be established or maintained and immune cells are stimulated by self-Ags. Although intracellular autoantigens are common, the origin of extracellular autoantigens is poorly defined and possibly more dangerous. In this study, we considered a mechanism for the origin of an extracellular autoantigen from the neuronal glutamate receptor subunit 3 (GluR3) in Rasmussen’s encephalitis, a severe form of pediatric epilepsy. We demonstrate that specific cleavage of GluR3 by granzyme B (GB), a serine protease released by activated immune cells, can generate the GluR3B autoantigenic peptide, but only if an internal N-linked glycosylation sequon within the GluR3-GB recognition sequence (ISND*S) is not glycosylated. However, this N-glycon sequon while glycosylated normally is inefficiently used and glycosylation can fail. These results suggest that GB/N-glycon sites may escape normal tolerance mechanisms and contribute to autoantibody-mediated immune diseases.
Cutting Edge: Dendritic Cells Are Sufficient to Cross-Present Self-Antigens to CD8 T Cells In Vivo
Authors: Kurts Christian , Cannarile Michael , Klebba Ina , Brocker Thomas 
Published: April 2014

AbstractThe mechanism of cross-presentation enables professional APCs to induce CD8 T cell-mediated immune responses against exogenous Ags. Through this mechanism, APCs can induce either immunity against infectious pathogens or tolerance against self-Ag residing in extralymphatic locations. An unanswered question in this field concerns the identity of the cross-presenting APC. All major classes of professional APCs, particularly dendritic cells, macrophages, and B cells, have previously been shown to be able to cross-present Ags in vitro. In the present study, we have created transgenic mice where MHC class I expression is driven selectively in dendritic cells and provide direct in vivo evidence that dendritic cells are sufficient to cross-present exogenous self-Ags and induce Ag-specific cell division of CD8-positive T cells.
Visualization of Syk-Antigen Receptor Interactions Using Green Fluorescent Protein: Differential Roles for Syk and Lyn in the Regulation of Receptor Capping and Internalization
Authors: Ma Haiyan , Yankee Thomas M. , Hu Jianjie , Asai David J. , Harrison Marietta L. , Geahlen Robert L. 
Published: April 2014

Abstract
The cross-linking of the B cell Ag receptor (BCR) is coupled to the stimulation of multiple intracellular signal transduction cascades via receptor-associated, protein tyrosine kinases of both the Src and Syk families. To monitor changes in the subcellular distribution of Syk in B cells responding to BCR cross-linking, we expressed in Syk-deficient DT40 B cells a fusion protein consisting of Syk coupled to green fluorescent protein. Treatment of these cells with anti-IgM Abs leads to the recruitment of the kinase from cytoplasmic and nuclear compartments to the site of the cross-linked receptor at the plasma membrane. The Syk-receptor complexes aggregate into membrane patches that redistribute to form a cap at one pole of the cell. Syk is not demonstrably associated with the internalized receptor. Catalytically active Syk promotes and stabilizes the formation of tightly capped BCR complexes at the plasma membrane. Lyn is not required for the recruitment of Syk to the cross-linked receptor, but is required for the internalization of the clustered BCR complexes. In the absence of Lyn, receptor-Syk complexes at the plasma membrane are long lived, and the receptor-mediated activation of the NF-AT transcription factor is enhanced. Thus, Lyn appears to function to negatively regulate aspects of BCR-dependent signaling by stimulating receptor internalization and down-regulation.
Stochastic Regulation of Cell Migration from the Efferent Lymph to Oxazolone-Stimulated Skin
Authors: West Charles A. , He Chufa , Su Mei , Rawn James , Swanson Scott , Hay John B. , Mentzer Steven J. 
Published: April 2014

Abstract
The systemic immune response is a dynamic process involving the trafficking of lymphocytes from the Ag-stimulated lymph node to the peripheral tissue. Studies in sheep have demonstrated several phases of cell output in the efferent lymph after Ag stimulation. When skin contact sensitizers are used as Ag, the efferent lymph cell output peaks ∼96 h after Ag stimulation and is temporally associated with the recruitment of cells into the skin. To investigate the relative contribution of this high-output phase of efferent lymphocytes to lymphocytic inflammation in the skin, we used a common contact sensitizer 2-phenyl-4-ethoxymethylene-5-oxazolone (oxazolone) to stimulate the skin and draining prescapular lymph node of adult sheep. The efferent lymph ducts draining the Ag-stimulated and contralateral control lymph nodes were cannulated throughout the experimental period. The lymphocytes leaving the lymph nodes during the 72-h period before maximum infiltration were differentially labeled with fluorescent tracers, reinjected into the arterial circulation, and tracked to the site of Ag stimulation. Quantitative tissue cytometry of the skin at the conclusion of the injection period (96 h after Ag stimulation) demonstrated more migratory cells derived from the Ag-stimulated lymph node than the contralateral control (median 18.5 vs 15.5 per field; p &lt; 0.05). However, when corrected for total cell output of the lymph node, the Ag-stimulated migratory cells were 3.8-fold more prevalent in the skin than the contralateral control cells. These results suggest that the in situ immune response generally mirrors the frequency of recruitable lymphocytes in the peripheral blood.
Murine B1 B Cells Require IL-5 for Optimal T Cell-Dependent Activation
Authors: Erickson Loren D. , Foy Teresa M. , Waldschmidt Thomas J. 
Published: April 2014

Abstract
T helper cell-driven activation of murine B cells has been shown to depend upon CD40-CD40 ligand (CD40L) interactions and a defined set of cytokines. These observations are primarily based on the use of conventional B cells obtained from the spleen. Therefore, it is presently unclear whether all mature B cell subsets found in the mouse have an equal dependence upon CD40-CD40L interactions and use the same T cell-derived cytokines. The present study tested the response of splenic follicular and marginal zone as well as peritoneal B2 and B1 B cells to Th cell stimulation. Splenic and peritoneal B cell subsets were sort purified based on CD23 expression, and cultured with rCD40L and cytokines or Th2 cells. The results demonstrate that follicular, marginal zone, and peritoneal B2 B cells require CD40-CD40L interactions and preferentially use IL-4 for optimal proliferation, differentiation, and isotype switching. In contrast, peritoneal B1 B cells use IL-5 in conjunction with CD40-CD40L interactions for maximal Th cell-dependent responses. Furthermore, B1 B cells are capable of proliferating, differentiating, and isotype switching in the absence of CD40-CD40L interactions. B1 B cells are able to respond to Th2 clones in the presence of anti-CD40L mAb as well as to Th2 clones derived from CD40L−/− mice. The CD40-CD40L-independent response of B1 B cells is attributable to the presence of both IL-4 and IL-5, and may explain the residual Ab response to T cell-dependent Ags in CD40L- or CD40-deficient mice, and in X-linked hyper-IgM (X-HIM) patients.
p59fyn(Fyn) Promotes the Survival of Anergic CD4−CD8− αβ TCR+ Cells but Negatively Regulates Their Proliferative Response to Antigen Stimulation
Authors: Utting Oliver , Priatel John J. , Teh Soo-Jeet , Teh Hung-Sia 
Published: April 2014

AbstractT cell anergy is characterized by alterations in TCR signaling that may play a role in controlling the unresponsiveness of the anergic cell. We have addressed questions regarding the importance of the Src kinase p59fyn (Fyn) in this process by using Fyn null mice. We demonstrate that a mature population of CD4−CD8− αβ TCR+ anergic T cells lacking Fyn have a substantial recovery of their proliferation defect in response to Ag stimulation. This recovery cannot be explained by ameliorated production of IL-2, and the improved proliferation correlates with an enhanced ability of the Fyn−/− anergic T cells to up-regulate the high affinity IL-2 receptor. We also observe that anergic CD4−CD8− αβ TCR+ T cells have a heightened survival ability that is partially dependent on the elevated levels of Fyn and IL-2 receptor β-chain expressed by these cells. The enhanced survival correlates with an increased capacity of the anergic cells to respond to IL-15. We conclude that Fyn plays an important role in aspects of T cell anergy pertaining to TCR signaling and to cell survival.
CTLA4Ig-Induced Linked Regulation of Allogeneic T Cell Responses
Authors: Lee Richard S. , Rusche James R. , Maloney Michaella E. , Sachs David H. , Sayegh Mohamed H. , Madsen Joren C. 
Published: April 2014

AbstractThe mechanisms by which CTLA4Ig exerts its powerful immunomodulatory effects are not clear. We show here that CTLA4Ig can induce linked regulation of allogeneic porcine T cell responses in vitro. Naive miniature swine SLAdd T cells were rendered hyporesponsive to specific allogeneic Ag after coculturing with MHC-mismatched SLAcc stimulators in the presence of CTLA4Ig. These Ag-specific hyporesponsive T cells were subsequently able to actively inhibit the allogeneic responses of naive syngeneic T cells in an MHC-linked fashion, as the responses of naive SLAdd responders against specific SLAcc and (SLAac)F1 stimulators were inhibited, but allogeneic responses against a 1:1 mixture of SLAaa (Ia, IIa) and SLAcc (Ic, IIc) were maintained. This inhibition could be generated against either class I or class II Ags, was radiosensitive, and required cell-cell contact. Furthermore, the mechanism of inhibition was not dependent upon a deletional, apoptotic pathway, but it was reversed by anti-IL-10 mAb. These data suggest that CTLA4Ig-induced inhibition of naive allogeneic T cell responses can be mediated through the generation of regulatory T cells via an IL-10-dependent mechanism.
TNF-α-Converting Enzyme Cleaves the Macrophage Colony-Stimulating Factor Receptor in Macrophages Undergoing Activation
Authors: Rovida Elisabetta , Paccagnini Alessandro , Del Rosso Mario , Peschon Jacques , Dello Sbarba Persio 
Published: April 2014

Abstract
We previously reported that macrophage activators such as LPS, IL-2, and IL-4 down-modulate the M-CSFR via a mechanism involving protein kinase C and phospholipase C. In this study, we showed that M-CSFR is shed from macrophage surface and identified the protease responsible for M-CSFR cleavage and down-modulation. The shedding of M-CSFR elicited by phorbol esters (tetradecanoylphorbol myristate acetate (TPA)) or LPS in murine BAC.1-2F5 macrophages was prevented by cation chelators, as well as hydroxamate-based competitive inhibitors of metalloproteases. We found that the protease cleaving M-CSFR is a transmembrane enzyme and that its expression is controlled by furin-like serine endoproteases, which selectively process transmembrane metalloproteases. M-CSFR down-modulation was inhibited by treating cells in vivo, before TPA stimulation, with an Ab raised against the extracellular, catalytic domain of proTNF-converting enzyme (TACE). TACE expression was confirmed in BAC.1-2F5 cells and found inhibited after blocking furin-dependent processing. Using TACE-negative murine Dexter-ras-myc cell monocytes, we found that in these cells TPA is unable to down-modulate M-CSFR expression. These data indicated that TACE is required for the TPA-induced M-CSFR cleavage. The possibility that the cleavage is indirectly driven by TACE via the release of TNF was excluded by treating cells in vivo with anti-TNF Ab. Thus, we concluded that TACE is the protease responsible for M-CSFR shedding and down-modulation in mononuclear phagocytes undergoing activation. The possible physiological relevance of this mechanism is discussed.
Enhancement of Human Cord Blood CD34+ Cell-Derived NK Cell Cytotoxicity by Dendritic Cells
Authors: Yu Ying , Hagihara Masao , Ando Kiyoshi , Gansuvd Balgansuren , Matsuzawa Hideyuki , Tsuchiya Takahide , Ueda Yoko , Inoue Hiroyasu , Hotta Tomomitsu , Kato Shunichi 
Published: April 2014

Abstract
NK cells and dendritic cells (DCs) are both important in the innate host defense. However, the role of DCs in NK cell-mediated cytotoxicity is unclear. In this study, we designed two culture systems in which human cord blood CD34+ cells from the same donor were induced to generate NK cells and DCs, respectively. Coculture of the NK cells with DCs resulted in significant enhancement of NK cell cytotoxicity and IFN-γ production. However, NK cell cytotoxicity and IFN-γ production were not increased when NK cells and DCs were grown together separated by a transwell membrane. Functional studies demonstrated that 1) concanamycin A, a selective inhibitor of perforin/granzyme B-based cytolysis, blocked DC-stimulated NK cytotoxicity against K562 cells; and 2) neutralizing mAb against Fas ligand (FasL) significantly reduced DC-stimulated NK cytotoxicity against Fas-positive Jurkat cells. In addition, a marked increase of FasL mRNA and FasL protein expression was observed in DC-stimulated NK cells. The addition of neutralizing mAb against IL-18 and IL-12 significantly suppressed DC-stimulated NK cell cytotoxicity. Neutralizing IFN-γ Ab almost completely inhibited NK cell cytotoxicity against Jurkat cells. These observations suggest that DCs enhance NK cell cytotoxicity by up-regulating both perforin/granzyme B- and FasL/Fas-based pathways. Direct interaction between DCs and NK cells is necessary for DC-mediated enhancement of NK cell cytotoxicity. Furthermore, DC-derived IL-18 and IL-12 were involved in the up-regulation of NK cell cytotoxicity, and endogenous IFN-γ production plays an important role in Fas-mediated cytotoxicity.
Extracellular ATP Induces a Distorted Maturation of Dendritic Cells and Inhibits Their Capacity to Initiate Th1 Responses
Authors: la Sala Andrea , Ferrari Davide , Corinti Silvia , Cavani Andrea , Di Virgilio Francesco , Girolomoni Giampiero 
Published: April 2014

AbstractDendritic cells (DCs) express functional purinergic receptors, but the effects of purine nucleotides on DC functions have been marginally investigated. In this study, we report on the ability of micromolar concentrations of ATP to affect the maturation and Ag-presenting function of monocyte-derived DCs in vitro. Chronic stimulation (24 h) of DCs with low, noncytotoxic ATP doses increased membrane expression of CD54, CD80, CD86, and CD83, slightly reduced the endocytic activity of DCs, and augmented their capacity to promote proliferation of allogeneic naive T lymphocytes. Moreover, ATP enhanced LPS- and soluble CD40 ligand-induced CD54, CD86, and CD83 expression. On the other hand, ATP markedly and dose-dependently inhibited LPS- and soluble CD40 ligand-dependent production of IL-1α, IL-1β, TNF-α, IL-6, and IL-12, whereas IL-1 receptor antagonist and IL-10 production was not affected. As a result, T cell lines generated from allogeneic naive CD45RA+ T cells primed with DCs matured in the presence of ATP produced lower amounts of IFN-γ and higher levels of IL-4, IL-5, and IL-10 compared with T cell lines obtained with LPS-stimulated DCs. ATP inhibition of TNF-α and IL-12 production by mature DCs was not mediated by PGs or elevation of intracellular cAMP and did not require ATP degradation. The inability of UTP and the similar potency of ADP to reproduce ATP effects indicated that ATP could function through the P2X receptor family. These results suggest that extracellular ATP may serve as an important regulatory signal to dampen IL-12 production by DCs and thus prevent exaggerated and harmful immune responses.
Rac and Phosphatidylinositol 3-Kinase Regulate the Protein Kinase B in FcεRI Signaling in RBL 2H3 Mast Cells
Authors: Djouder Nabil , Schmidt Gudula , Frings Monika , Cavalié Adolfo , Thelen Marcus , Aktories Klaus 
Published: April 2014

Abstract
FcεRI signaling in rat basophilic leukemia cells depends on phosphatidylinositol 3-kinase (PI3-kinase) and the small GTPase Rac. Here, we studied the functional relationship among PI3-kinase, its effector protein kinase B (PKB), and Rac using inhibitors of PI3-kinase and toxins inhibiting Rac. Wortmannin, an inhibitor of PI3-kinase, blocked FcεRI-mediated tyrosine phosphorylation of phospholipase Cγ, inositol phosphate formation, calcium mobilization, and secretion of hexosaminidase. Similarly, Clostridium difficile toxin B, which inactivates all Rho GTPases including Rho, Rac and Cdc42, and Clostridium sordellii lethal toxin, which inhibits Rac (possibly Cdc42) but not Rho, blocked these responses. Stimulation of the FcεRI receptor induced a rapid increase in the GTP-bound form of Rac. Whereas toxin B inhibited the Rac activation, PI3-kinase inhibitors (wortmannin and LY294002) had no effect on activation of Rac. In line with this, wortmannin had no effect on tyrosine phosphorylation of the guanine nucleotide exchange factor Vav. Wortmannin, toxin B, and lethal toxin inhibited phosphorylation of PKB on Ser473. Similarly, translocation of the pleckstrin homology domain of PKB tagged with the green fluorescent protein to the membrane, which was induced by activation of the FcεRI receptor, was blocked by inhibitors of PI3-kinase and Rac inactivation. Our results indicate that in rat basophilic leukemia cells Rac and PI3-kinase regulate PKB and suggest that Rac is functionally located upstream and/or parallel of PI3-kinase/PKB in FcεRI signaling.