bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Solvent-Inaccessible Cys67 Residue of HLA-B27 Contributes to T Cell Recognition of HLA-B27/Peptide Complexes
Authors: Appel Heiner , Kuon Wolfgang , Kuhne Maren , Hülsmeyer Martin , Kollnberger Simon , Kuhlmann Stefanie , Weiss Elisabeth , Zeitz Martin , Wucherpfennig Kai , Bowness Paul , Sieper Joachim 
Published: April 2014

AbstractCrystallographic studies have suggested that the cysteine at position 67 (Cys67) in the B pocket of the MHC molecule HLA-B*2705 is of importance for peptide binding, and biophysical studies have documented altered thermodynamic stability of the molecule when Cys67 was mutated to serine (Ser67). In this study, we used HLA-B27.Cys67 and HLA-B27.Ser67 tetramers with defined T cell epitopes to determine the contribution of this polymorphic, solvent-inaccessible MHC residue to T cell recognition. We generated these HLA-B27 tetramers using immunodominant viral peptides with high binding affinity to HLA-B27 and cartilage-derived peptides with lower affinity. We demonstrate that the yield of refolding of HLA-B27.Ser67 molecules was higher than for HLA-B27.Cys67 molecules and strongly dependent on the affinity of the peptide. T cell recognition did not differ between HLA-B27.Cys67 and HLA.B27.Ser67 tetramers for the viral peptides that were investigated. However, an aggrecan peptide-specific T cell line derived from an HLA-B27 transgenic BALB/c mouse bound significantly stronger to the HLA-B27.Cys67 tetramer than to the HLA-B27.Ser67 tetramer. Modeling studies of the molecular structure suggest the loss of a SH … π hydrogen bond with the Cys→Ser substitution in the HLA-B27 H chain which reduces the stability of the HLA-B27/peptide complex. These results demonstrate that a solvent-inaccessible residue in the B pocket of HLA-B27 can affect TCR binding in a peptide-dependent fashion.
“Pruning” of Alloreactive CD4+ T Cells Using 5- (and 6-)Carboxyfluorescein Diacetate Succinimidyl Ester Prolongs Skin Allograft Survival
Authors: Watson Debbie , Zhang Geoff Yu , Sartor Mary , Alexander Stephen I. 
Published: April 2014

AbstractRemoval of alloreactive cells by either thymic deletion or deletion/anergy in the periphery is regarded as crucial to the development of tolerance. Dyes, such as CFSE, that allow monitoring of cell division suggest that in vitro proliferation could be a used as a way of “pruning” alloreactive cells while retaining a normal immune repertoire with retention of memory to previously encountered pathogens. This would overcome the problems occurring as a result of therapies that use massive depletion of T cells to allow acceptance of organ transplants or bone marrow grafts. We therefore used a skin graft model of CD4-mediated T cell rejection across a major H-2 mismatch (C57BL/6 (H-2b) to BALB/c (H-2d) mice) to evaluate whether nondividing CD4+ T cells derived from a mixed lymphocyte culture would exhibit tolerance to a skin graft from the initial stimulator strain. We demonstrate that selective removal of dividing alloreactive CD4+ T cells resulted in marked specific prolongation of allogeneic skin graft survival, and that the nondividing CD4+ T cells retained a broad TCR repertoire and the ability to maintain memory. This novel way of depleting alloreactive T cells may serve as a useful strategy in combination with other mechanisms to achieve transplant tolerance.
Pax5-Deficient Mice Exhibit Early Onset Osteopenia with Increased Osteoclast Progenitors
Authors: Horowitz Mark C. , Xi Yougen , Pflugh David L. , Hesslein David G. T. , Schatz David G. , Lorenzo Joseph A. , Bothwell Alfred L. M. 
Published: April 2014

AbstractPax5 encodes BSAP, a member of the paired box domain transcription factors, whose expression is restricted to B lymphocyte lineage cells. Pax5−/− mice have a developmental arrest of the B cell lineage at the pro-B cell stage. We show here that Pax5−/− mice are severely osteopenic, missing 60% of their bone mass. The osteopenia can be accounted for by a &gt;100% increase in the number of osteoclasts in bone measured histomorphometrically. This is not due to a lack of B cells, because other strains of B cell-deficient mice do not exhibit this phenotype. There was no difference in the number of osteoclasts produced in vitro by wild-type and Pax5−/− bone marrow cells. In contrast, spleen cells from Pax5−/− mice produce as much as five times the number of osteoclasts as control spleen cells. Culture of Pax5−/− spleen cells yields a population of adherent cells that grow spontaneously in culture without added growth factors for &gt;4 wk. These cells have a monocyte phenotype, produce large numbers of osteoclasts when induced in vitro, and therefore are highly enriched in osteoclast precursors. These data demonstrate a previously unsuspected connection between B cell and osteoclast development and a key role for Pax5 in the control of osteoclast development.
Early and Quantal (by Litter) Expression of Insulin Autoantibodies in the Nonobese Diabetic Mice Predict Early Diabetes Onset
Authors: Melanitou Evie , Devendra Devasenan , Liu Edwin , Miao Dongmei , Eisenbarth George S. 
Published: April 2014

Abstract
Aiming to study the early stages of type 1 diabetes phenotype, before insulitis appears, we measured insulin autoantibodies (IAA) between 3 and 5 wk of age in the NOD mouse (early-IAA (E-IAA)). We report that IAA are found as early as at 3 wk of age, at weaning, and their expression is a quantal phenotype. Maternal autoantibody status influences this early phenotype, because animals of litters issued from IAA-positive ante partum mothers develop E-IAA with a significantly higher incidence than animals issued from IAA-negative mothers. These E-IAA represent synthesized rather than transplacental autoantibodies, as evidenced by higher levels in many offspring compared with maternal IAA, and negative as well as positive offspring in the same litters and it correlates with early diabetes onset, defining the first autoimmune window in diabetes pathogenesis. Therefore, autoimmune processes leading to type 1 diabetes initiate early in life, are influenced by maternal autoantibody status, and can be revealed by the presence of IAA. Our data suggest that the mechanisms responsible for the breakdown of self-tolerance are subjected not only to genetic predisposition, but also to the physiological status of the mother. Pathological progression to autoimmunity is marked by the presence of immunological windows relating early steps with final disease onset.
The Contraction Phase of Virus-Specific CD8+ T Cells Is Unaffected by a Pan-Caspase Inhibitor
Authors: Nussbaum Alexander K. , Whitton J. Lindsay 
Published: April 2014

AbstractThe effectiveness of protection conferred by CD8+ memory T cells is determined by both their quality and their quantity, which suggests that vaccine efficacy might be improved if it were possible to increase the size of the memory pool. Approximately 90% of virus-specific CD8+ T cells die during the contraction phase and, herein, we have attempted to increase the memory pool by reducing CD8+ T cell death. CD8+ T cell contraction has been attributed to apoptosis, or programmed cell death (PCD), which, classically, is dependent on caspases. Caspase-dependent PCD can be prevented by the pan-caspase inhibitor benzyloxycarbonyl-Val-Ala-Asp (OMe)-fluoromethylketone (zVAD), and here we evaluate the effect of this compound on virus-specific T cell responses in mice. zVAD prevented caspase-dependent PCD of freshly isolated virus-specific T cells in tissue culture, and a fluorescent analog, FITC-VAD, entered CD8+ T cells following in vivo injection. However, despite using 11 different regimens of zVAD administration in vivo, no significant effects on CD8+ or CD4+ memory T cell numbers were observed. Furthermore, the CD8+ memory T cell responses to secondary virus infection were indistinguishable, both qualitatively and quantitatively, in zVAD-treated and normal mice. The absence of effect cannot be attributed to a technical flaw, because identical doses of zVAD were able to rescue mice from hepatocyte apoptosis and lethal intrahepatic hemorrhage, induced by inoculation of anti-Fas Ab. We conclude that the contraction phase of the virus-specific T cell response is unlikely to require caspase-dependent PCD. We propose that contraction can be mediated by an alternative, caspase-independent pathway(s).
Cellular FLIP (Long Isoform) Overexpression in T Cells Drives Th2 Effector Responses and Promotes Immunoregulation in Experimental Autoimmune Encephalomyelitis
Authors: Tseveleki Vivian , Bauer Jan , Taoufik Era , Ruan Chengmai , Leondiadis Leondios , Haralambous Sylva , Lassmann Hans , Probert Lesley 
Published: April 2014

AbstractCellular FLIP (c-FLIP) is an endogenous inhibitor of death receptor-induced apoptosis through the caspase 8 pathway. It is an NF-κB-inducible protein thought to promote the survival of T cells upon activation, and its down-regulation has been implicated in activation-induced cell death. We have generated transgenic mice overexpressing human c-FLIP long form (c-FLIPL) specifically in T cells using the CD2 promoter (TgFLIPL). TgFLIPL mice exhibit increased IgG1 production upon stimulation by a T cell-dependent Ag and a markedly enhanced contact hypersensitivity response to allergen. In addition to showing augmented Th2-type responses, TgFLIPL mice are resistant to the development of myelin oligodendrocyte glycoprotein 35–55 peptide-induced experimental autoimmune encephalomyelitis, a Th1-driven autoimmune disease. In vitro analyses revealed that T cells of TgFLIPL mice proliferate normally, but produce higher levels of IL-2 and show preferential maturation of Th2 cytokine-producing cells in response to antigenic stimulation. After adoptive transfer, these (Th2) cells protected wild-type recipient mice from experimental autoimmune encephalomyelitis induction. Our results show that the constitutive overexpression of c-FLIPL in T cells is sufficient to drive Th2 polarization of effector T cell responses and indicate that it might function as a key regulator of Th cell differentiation.
Role of CTLA-4 in the Activation of Single- and Double-Positive Thymocytes
Authors: Kwon Hyokjoon , Jun Hee-Sook , Khil Lee-Yong , Yoon Ji-Won 
Published: April 2014

AbstractCTLA-4, a homologue of CD28, is a negative regulator of T cell activation in the periphery and is transiently expressed on the cell surface after T cell activation. However, the role of CTLA-4 in T cell activation in the thymus is not clear. This investigation was initiated to determine the role of CTLA-4 in the activation of CD4+CD8+ double-positive (DP) and CD4+CD8− and CD4−CD8+ single-positive (SP) thymocytes using fetal thymic organ cultures (FTOC) of MHC class II-restricted, OVA323–339-restricted TCR transgenic mice (DO11.10). We found that treatment of the FTOC with anti-CTLA-4-blocking Ab during activation with OVA323–339 increased the proportion and number of DP thymocytes, but decreased the proportion and number of SP thymocytes compared with OVA323–339-stimulated FTOC without anti-CTLA-4 Ab treatment. In addition, anti-CTLA-4 Ab treatment inhibited OVA323–339-induced expression of the early activation marker, CD69, in DP thymocytes, but increased CD69 in SP thymocytes. Similarly, CTLA-4 blockage decreased phosphorylation of ERK in DP thymocytes by Ag-specific TCR engagement, but increased phosphorylation of ERK in SP thymocytes. CTLA-4 blockage inhibited deletion of DP thymocytes treated with a high dose of OVA323–339, whereas CTLA-4 blockage did not inhibit deletion of DP thymocytes treated with a low dose of OVA323–339. We conclude that CTLA-4 positively regulates the activation of DP thymocytes, resulting in their deletion, whereas blocking CTLA-4 suppresses the activation of DP thymocytes, leading to inhibition of DP thymocyte deletion. In contrast, CTLA-4 negatively regulates the activation of SP thymocytes.
Tolerance Induction by Veto CTLs in the TCR Transgenic 2C Mouse Model. I. Relative Reactivity of Different Veto Cells
Authors: Reich-Zeliger Shlomit , Bachar-Lustig Esther , Gan Judith , Reisner Yair 
Published: April 2014

AbstractSeveral bone marrow cells and lymphocyte subpopulations, known as veto cells, were shown to induce transplantation tolerance across major histocompatibility Ags. Due to the low frequency of the effector T cells against which the veto cells inhibitory activity is aimed, the fate of the effector cells was traditionally followed indirectly by functional limiting dilution assays, which are cumbersome and depend on numerous parameters. In the present study the fate of the effector T cells was monitored directly by FACS, using TCR transgenic mouse CD8+ T cells in which the transgene is directed against H-2d (the 2C model). This assay is validated by demonstrating the potency, selectivity, radiation sensitivity, and contact dependency of anti-third-party CTLs previously demonstrated by the limiting dilution assay. In contrast to veto CTLs, nonactivated CD8+ T cells lack veto activity. Comparison by FACS in the 2C model revealed a hierarchy of veto cells, in the order of veto CTLs activated NK cells, activated CD4+ T cells, and activated B cells. The latter cells as well as nonactivated CD4+ or NK cells were shown to be completely devoid of veto activity.
Tolerance Induction by Veto CTLs in the TCR Transgenic 2C Mouse Model. II. Deletion of Effector Cells by Fas-Fas Ligand Apoptosis
Authors: Reich-Zeliger Shlomit , Gan Judith , Bachar-Lustig Esther , Reisner Yair 
Published: April 2014

AbstractThe direct assay of veto CTLs in the 2C mouse model enables monitoring, by FACS, the fate of the TCR transgenic effector CD8+ T cells, the transgene of which can be stained with clonotypic Ab 1B2. After the addition of veto cells, CD8+1B2+ effector cells increasingly express annexin V, and maximal apoptosis is attained 72 h after initiation of MLR. This veto activity can be partially blocked by anti-CD8 Abs directed against the allele expressed by the veto CTLs, but not by the effector cells. When effector CD8+ T cells were from 2C mice, which lack Fas expression ((2CX lpr)F2), deletion of effector cells was not exhibited by veto cells. The protein levels of the apoptosis inhibitors FLIP and Bcl2 in purified CD8+1B2+ effector cells at different time points after MLR showed an initial up-regulation of these inhibitors, with marked reduction of FLIP, but not of Bcl2, by 48 h after initiation of culture. Taken together, these results are in accordance with a Fas-FasL-based mechanism in which prolonged binding between the effector cell and the veto cell might be required to allow FLIP to be down-regulated. Such prolonged interaction might be afforded through the interaction of CD8 molecules on the veto cell with the α3 domain of H2 class 1 on the effector cell.
Impact of CCR7 on Priming and Distribution of Antiviral Effector and Memory CTL
Authors: Junt Tobias , Scandella Elke , Förster Reinhold , Krebs Philippe , Krautwald Stefan , Lipp Martin , Hengartner Hans , Ludewig Burkhard 
Published: April 2014

AbstractThe chemokine receptor CCR7 is a key factor in the coordinate migration of T cells and dendritic cells (DC) into and their localization within secondary lymphoid organs. In this study we investigated the impact of CCR7 on CD8+ T cell responses by infecting CCR7−/− mice with lymphocytic choriomeningitis virus (LCMV). We found that the absence of CCR7 affects the magnitude of an antiviral CTL response during the acute phase, with reduced numbers of virus-specific CTL in all lymphoid and nonlymphoid organs tested. On the single cell level, CCR7-deficient CTL gained full effector function, such that antiviral protection in CCR7-deficient mice was complete, but delayed. Similarly, adoptive transfer experiments using DC from CCR7-deficient or competent mice for the priming of CCR7-positive or CCR7-negative CD8+ T cells, respectively, revealed that ectopic positioning of DC and CTL outside organized T cell zones results in reduced priming efficacy. In the memory phase, CCR7-deficient mice maintained a stable LCMV-specific CTL population, predominantly in nonlymphoid organs, and rapidly mounted protective CTL responses against a challenge infection with a vaccinia virus recombinant for the gp33 epitope of LCMV. Taken together, the CCR7-dependent organization of the T cell zone does not appear to be a prerequisite for antiviral effector CTL differentiation and the sustenance of antiviral memory responses in lymphoid or peripheral tissues.
Molecular Characterization of a Novel Immune Receptor Restricted to the Monocytic Lineage
Authors: Aguilar Helena , Álvarez-Errico Damiana , García-Montero Andrés C. , Orfao Alberto , Sayós Joan , López-Botet Miguel 
Published: April 2014

AbstractHomology basic local alignment search tool search was conducted using a sequence encoding for a novel inhibitory receptor (IREM-1) cloned in our laboratory and a previously described homologous sequence termed CMRF-35. On the basis of this information, we cloned a full length cDNA corresponding to a novel member of this family, termed immune receptor expressed by myeloid cells 2 (IREM-2). The gene, located in chromosome 17q25.1, encodes for a protein of 205 aa that contains an extracellular region comprising an Ig-like domain and a transmembrane region with a positively charged amino acid residue (lysine), that predicted its putative association with an adapter molecule. Indeed, the interaction between IREM-2 and DAP-12 was confirmed in transfected COS-7 cells. By generating specific Abs and using bone marrow and PBMCs, we observed that IREM-2 expression appeared to be restricted to mature hemopoietic cells of the monocytic and myeloid dendritic cell lineages. In vitro differentiation to macrophages or immature dendritic cells down-regulated IREM-2 expression. Upon engagement with the specific mAbs, IREM-2 expressed in rat basophilic leukemia cells together with DAP-12, induced NFAT transcriptional activity; moreover, IREM-2 engagement on monocytes induced TNF-α production. Taken together, our results indicate that IREM-2 is a novel activating receptor of the Ig-superfamily in the monocytic lineage.
Phenotypic and Functional Characterization of CD4 T Cells Expressing Killer Ig-Like Receptors
Authors: van Bergen Jeroen , Thompson Allan , van der Slik Arno , Ottenhoff Tom H. M. , Gussekloo Jacobijn , Koning Frits 
Published: April 2014

AbstractKiller Ig-like receptors (KIR) are commonly found on human NK cells, γδ T cells, and CD8 T cells. Although KIR+ CD4 T cells are found in certain patients, their prevalence in healthy donors is controversial. We now provide definitive proof that such cells are present in most individuals, and report on their frequency, surface phenotype, cytokine profile, and Ag specificity. The number of KIR+ CD4 T cells detected in peripheral blood increased with age. In contrast with regular KIR− CD4 T cells, the majority of KIR+ CD4 T cells lacked surface expression of CD27, CD28, CCR4, and CCR7, but did express CD57 and 2B4. In addition, KIR were detected on approximately one-tenth of CD28− and CD57+ memory CD4 T cells. In line with the absence of the Th2 marker CCR4, the KIR+ CD4 cells produced mainly IFN-γ and little IL-4, IL-10, or IL-17 upon TCR triggering. Furthermore, the KIR+ population contained cells that responded to recall Ags in an HLA class II-restricted fashion. Together, our data indicate that KIR-expressing CD4 T cells are predominantly HLA class II-restricted effector memory Th1 cells, and that a significant, previously unrecognized fraction of effector memory Th1 cells expresses KIR.
Individual Nonobese Diabetic Mice Exhibit Unique Patterns of CD8+ T Cell Reactivity to Three Islet Antigens, Including the Newly Identified Widely Expressed Dystrophia Myotonica Kinase
Authors: Lieberman Scott M. , Takaki Toshiyuki , Han Bingye , Santamaria Pere , Serreze David V. , DiLorenzo Teresa P. 
Published: April 2014

AbstractSpontaneous autoimmune diabetes development in NOD mice requires both CD8+ and CD4+ T cells. Three pathogenic CD8+ T cell populations (represented by the G9C8, 8.3, and AI4 clones) have been described. Although the Ags for G9C8 and 8.3 are known to be insulin and islet-specific glucose-6-phosphatase catalytic subunit-related protein, respectively, only mimotope peptides had previously been identified for AI4. In this study, we used peptide/MHC tetramers to detect and quantify these three pathogenic populations among β cell-reactive T cells cultured from islets of individual NOD mice. Even within age-matched groups, each individual mouse exhibited a unique distribution of β cell-reactive CD8+ T cells, both in terms of the number of tetramer-staining populations and the relative proportion of each population in the islet infiltrate. Thus, the inflammatory process in each individual follows its own distinctive course. Screening of a combinatorial peptide library in positional scanning format led to the identification of a peptide derived from dystrophia myotonica kinase (DMK) that is recognized by AI4-like T cells. Importantly, the antigenic peptide is naturally processed and presented by DMK-transfected cells. DMK is a widely expressed protein that is nonetheless the target of a β cell-specific autoimmune response.
Mechanisms for Macrophage-Mediated HIV-1 Induction
Authors: Devadas Krishnakumar , Hardegen Neil J. , Wahl Larry M. , Hewlett Indira K. , Clouse Kathleen A. , Yamada Kenneth M. , Dhawan Subhash 
Published: April 2014

AbstractViral latency is a long-term pathogenic condition in patients infected with HIV-1. Low but sustained virus replication in chronically infected cells can be activated by stimulation with proinflammatory cytokines such as TNF-α, IL-1 β, or other host factors. However, the precise mechanism by which cellular activation induces latently infected cells to produce virions has remained unclear. In the present report, we present evidence that activation of HIV-1 replication in latently infected U1 or ACH2 cells by human macrophages is mediated by a rapid nuclear localization of NF-κB p50/p65 dimer with concomitant increased expression of proinflammatory cytokines. Multiplexed RT-PCR amplification of mRNA isolated from cocultures of macrophages and U1 and ACH2 cells showed significant induction of IL-1β, IL-6, IL-8, TNF-α, and TGF-β expression within 3 h of coincubation. Fixation of macrophages, U-1, or ACH2 cells with paraformaldehyde before coculture completely abrogated the induction of NF-κB subunits and HIV-1 replication, suggesting that cooperative interaction between the two cell types is an essential process for cellular activation. Pretreatment of macrophage-U1 or macrophage-ACH2 cocultures with neutralizing anti-TNF-α Ab down-regulated the replication of HIV-1. In addition, pretreatment of macrophage-U1 or macrophage-ACH2 cocultures with the NF-κB inhibitor (E)3-[(4-methylphenyl)sulfonyl]-2-propenenitrile (BAY 11-7082) prevented the induction of cytokine expression, indicating a pivotal role of NF-κB-mediated signaling in the reactivation of HIV-1 in latently infected cells by macrophages. These results provide a mechanism by which macrophages induce HIV-1 replication in latently infected cells.