bluuebunny/crossref_metadata_2025_split huggingface dataset:
Autoreactive T Cells Mediate NK Cell Degeneration in Autoimmune Disease
Authors: Liu Ruolan , Kaer Luc Van , Cava Antonio La , Price Mary , Campagnolo Denise I. , Collins Mary , Young Deborah A. , Vollmer Timothy L. , Shi Fu-Dong 
Published: April 2014

Abstract
Emerging evidence indicates that NK cells play an important and complex role in autoimmune disease. Humans with autoimmune diseases often have reduced NK cell numbers and compromised NK cell functions. Mechanisms underlying this NK cell degeneration and its biological significance are not known. In this study we show that, in an experimental model of human autoimmune myasthenia gravis induced by a self-Ag, the acetylcholine receptor, NK cells undergo proliferation during the initiation of autoimmunity, followed by significant degeneration associated with the establishment of the autoreactive T cell response. We show that NK cell degeneration was mediated by IL-21 derived from autoreactive CD4+ T cells, and that acetylcholine receptor-immunized IL-21R-deficient mice, with competent NK cells, developed exacerbated autoimmunity. Thus, NK cell degeneration may serve as a means evolved by the immune system to control excessive autoimmunity.
Interleukin-2-Dependent Mechanisms of Tolerance and Immunity In Vivo
Authors: Antony Paul A. , Paulos Chrystal M. , Ahmadzadeh Mojgan , Akpinarli Akgül , Palmer Douglas C. , Sato Noriko , Kaiser Andrew , Heinrichs Christian , Klebanoff Christopher A. , Tagaya Yutaka , Restifo Nicholas P. 
Published: April 2014

Abstract
IL-2 is a critical T cell growth factor in vitro, but predominantly mediates tolerance in vivo. IL-2 is mainly produced by CD4+ Th cells, but the role of Th cell-derived IL-2 in vivo is controversial. We demonstrate that during immunity to a tumor/self-Ag, the predominant role of Th cell-derived IL-2 was to maintain IL-2Rα (CD25) on CD4+ T regulatory cells (Treg), which resulted in their maintenance of the Treg cell lineage factor, Forkhead/winged helix transcription factor (Foxp3), and tolerance. However, in the absence of Treg cells, Th cell-derived IL-2 maintained effector T cells and caused autoimmunity. IL-2R signaling was indispensable for Treg cell homeostasis and efficient suppressor function in vivo, but, surprisingly, was not required for their generation, because IL-2−/− and CD25−/− mice both contained Foxp3+ T cells in the periphery. IL-2R signaling was also important for CD8+ T cell immunity, because CD25−/− tumor-reactive CD8+ T cells failed to affect established tumors. Conversely, IL-2R signaling was not required for Th cell function. Lastly, administration of anti-IL-2 plus exogenous IL-15 to tumor-bearing mice enhanced the adoptive immunotherapy of cancer. Therefore, Th cell-derived IL-2 paradoxically controls both tolerance and immunity to a tumor/self-Ag in vivo.
CXCR5/CXCL13 Interaction Is Important for Double-Negative Regulatory T Cell Homing to Cardiac Allografts
Authors: Lee Boris P.-L. , Chen Wenhao , Shi Hui , Der Sandy D. , Förster Reinhold , Zhang Li 
Published: April 2014

Abstract
Accumulating evidence indicates that regulatory T (Treg) cells control development of various diseases both systemically and locally. However, molecular mechanisms involved in Treg cell homing remain elusive. We have shown previously that αβTCR+CD3+CD4−CD8− double-negative (DN) Treg cells selectively accumulate in tolerant allografts to maintain localized immune regulation. However, the molecular mechanism leading to the accumulation of DN Treg cells in tolerant grafts was not known. Our cDNA microarray analysis revealed significant up-regulation of chemokine receptor CXCR5 mRNA in DN Treg clones compared with nonregulatory clones. In this study, we examined the importance of CXCR5 in mediating DN Treg migration. Compared with CD4 and CD8 T cells, both primary DN Treg cells and clones constitutively express high levels of CXCR5 protein, enabling them to migrate toward increasing CXCL13 gradients in vitro. After infusion into recipient mice, CXCR5+ DN Treg clones, but not their CXCR5− mutants, preferentially accumulated in cardiac allografts and could prevent graft rejection. Furthermore, we found that allogeneic cardiac allografts express high levels of CXCL13 mRNA compared with either recipient native hearts or nontransplanted donor hearts. Ab neutralization of CXCL13 abrogated DN Treg cell migration in vitro and prevented in vivo homing of DN Treg clones into allografts. These data demonstrate that DN Treg cells preferentially express CXCR5, and interaction of this chemokine receptor with its ligand CXCL13 plays an important role in DN Treg cell migration both in vitro and in vivo.
Human CD4+CD25high Regulatory T Cells Modulate Myeloid but Not Plasmacytoid Dendritic Cells Activation
Authors: Houot Roch , Perrot Ivan , Garcia Eric , Durand Isabelle , Lebecque Serge 
Published: April 2014

Abstract
Human CD4+CD25+ regulatory T cells (Treg) play an essential role in the prevention of autoimmune diseases. However, the mechanisms of immune suppression and the spectrum of cells they target in vivo remain incompletely defined. In particular, although Treg directly suppress conventional T cells in vitro, they have been shown to inhibit the Ag-presenting functions of macrophage- and monocyte-derived dendritic cells (DC). We have now studied the maturation of human blood-derived myeloid DC and plasmacytoid DC activated with TLR ligands in the presence of Treg. Preactivated Treg suppressed strongly TLR-triggered myeloid DC maturation, as judged by the blocking of costimulatory molecule up-regulation and the inhibition of proinflammatory cytokines secretion that resulted in poor Ag presentation capacity. Although IL-10 played a prominent role in inhibiting cytokines secretion, suppression of phenotypic maturation required cell-cell contact and was independent of TGF-β and CTLA-4. In contrast, the acquisition of maturation markers and production of cytokines by plasmacytoid DC triggered with TLR ligands were insensitive to regulatory T cells. Therefore, human Treg may enlist myeloid, but not plasmacytoid DC for the initiation and the amplification of tolerance in vivo by restraining their maturation after TLR stimulation.
CD72 Down-Modulates BCR-Induced Signal Transduction and Diminishes Survival in Primary Mature B Lymphocytes
Authors: Li Daniel H. , Tung James W. , Tarner Ingo H. , Snow Andrew L. , Yukinari Tsuyoshi , Ngernmaneepothong Rachel , Martinez Olivia M. , Parnes Jane R. 
Published: April 2014

AbstractCD72, a 45-kDa type II transmembrane glycoprotein carrying an ITIM motif, is believed to be an inhibitory coreceptor of the BCR. Mature B cells lacking CD72 show enhanced Ca2+ mobilization and are hyperproliferative in response to BCR ligation. However, the signal transduction pathways downstream of BCR signaling that transmit the inhibitory effect of CD72 in mature B cells remain unknown. To address this question, we used hen egg lysozyme-specific BCR transgenic mice to elucidate the differential cell signaling between wild-type and CD72-deficient B cells in response to hen egg lysozyme Ag stimulation. Our results demonstrate that CD72 predominantly down-regulates the major signal transduction pathways downstream of the BCR, including NF-AT, NF-κB, ERK, JNK, p38-MAPK, and PI3K/Akt in mature B cells. CD72 ligation with anti-CD72 Ab (K10.6), which mimics the binding of CD100 (a natural ligand for CD72) to release the inhibitory function of CD72, augments cell proliferation, Ca2+ flux, IκBα activation, and ERK MAPK activity upon Ag stimulation in wild-type B cells. In addition, we show direct evidence that CD72 promotes cell cycle arrest and apoptosis after Ag stimulation in mature B cells. Taken together, our findings conclude that CD72 plays a dominant role as a negative regulator of BCR signaling in primary mature B lymphocytes.
Stimulation of Human Endothelium with IL-3 Induces Selective Basophil Accumulation In Vitro
Authors: Lim Lina H. K. , Burdick Monica M. , Hudson Sherry A. , Mustafa Fatimah Bte , Konstantopoulos Konstantinos , Bochner Bruce S. 
Published: April 2014

AbstractBasophils have been shown to accumulate in allergic airways and other extravascular sites. Mechanisms responsible for the selective recruitment of basophils from the blood into tissue sites remain poorly characterized. In this study, we characterized human basophil rolling and adhesion on HUVECs under physiological shear flow conditions. Interestingly, treatment of endothelial cells with the basophil-specific cytokine IL-3 (0.01–10 ng/ml) promoted basophil and eosinophil, but not neutrophil, rolling and exclusively promoted basophil adhesion. Preincubation of HUVECs with an IL-3R-blocking Ab (CD123) before the addition of IL-3 inhibited basophil rolling and adhesion, implicating IL-3R activation on endothelial cells. Incubation of basophils with neuraminidase completely abolished both rolling and adhesion, indicating the involvement of sialylated structures in the process. Abs to the β1 integrins, CD49d and CD49e, as well as to P-selectin and P-selectin glycoprotein ligand 1, inhibited basophil rolling and adhesion. Furthermore, blocking chemokine receptors expressed by basophils, such as CCR2, CCR3, and CCR7, demonstrated that CCR7 was involved in the observed recruitment of basophils. These data provide novel insights into how IL-3, acting directly on endothelium, can cause basophils to preferentially interact with blood vessels under physiological flow conditions and be selectively recruited to sites of inflammation.
Murine Model of Immune-Mediated Rejection of the Acute Lymphoblastic Leukemia 70Z/3
Authors: Labbe Alain , Tran Anne H. , Paige Christopher J. 
Published: April 2014

Abstract
70Z/3 is a murine pre-B cell leukemia line derived from BDF1 mice and has been used in the study of signaling pathways in B cells. 70Z/3 cells were initially found to cause widespread disease upon injections in animals. We have isolated 70Z/3 variants divergent in their capacity to lead to morbidity after injections. One variant, 70Z/3-NL, elicits an immune response protecting the animal from tumor growth. Another variant, 70Z/3-L, does not induce an effective immune response and causes morbidity. We demonstrated that both CD4+ and CD8+ T cells are required for the rejection of 70Z/3-NL cells. Interestingly, the immune response generated against 70Z/3-NL cells was found to protect against a challenge with the lethal variant, 70Z/3-L. This indicates that although both lines can be recognized and killed by the immune system, only 70Z/3-NL is capable of inducing a protective response. Further observations, using subclones isolated from 70Z/3-NL, demonstrated that immune recognition of a portion of the cells was sufficient for protection. Depletion of CD4+ and CD8+ T cells in animals injected previously with 70Z/3-NL cells showed that T cells, and not Abs, were required for the maintenance of the protection initiated by 70Z/3-NL. We tested the capacity of 70Z/3-NL cells to treat mice challenged with 70Z/3-L. We can delay injections of 70Z/3-NL and still provide protection for the animals. We have a model of immune-mediated rejection which will allow us to dissect the requirements for the initiation of immune responses against an ALL tumor cell line.
Notch-1 Up-Regulation and Signaling following Macrophage Activation Modulates Gene Expression Patterns Known to Affect Antigen-Presenting Capacity and Cytotoxic Activity
Authors: Monsalve Eva , Pérez Miguel A. , Rubio Antonio , Ruiz-Hidalgo María José , Baladrón Victoriano , García-Ramírez José J. , Gómez Juan C. , Laborda Jorge , Díaz-Guerra María José M. 
Published: April 2014

AbstractNotch signaling has been extensively implicated in cell-fate determination along the development of the immune system. However, a role for Notch signaling in fully differentiated immune cells has not been clearly defined. We have analyzed the expression of Notch protein family members during macrophage activation. Resting macrophages express Notch-1, -2, and -4, as well as the Notch ligands Jagged-1 and -2. After treatment with LPS and/or IFN-γ, we observed a p38 MAPK-dependent increase in Notch-1 and Jagged-1 mRNA and protein levels. To study the role of Notch signaling in macrophage activation, we forced the transient expression of truncated, active intracellular Notch-1 (Notch-IC) proteins in Raw 264.7 cells and analyzed their effects on the activity of transcription factors involved in macrophage activation. Notch-IC increased STAT-1-dependent transcription. Furthermore, Raw 264.7 Notch-IC stable transfectants increased STAT1-dependent transcription in response to IFN-γ, leading to higher expression of IFN regulatory factor-1, suppressor of cytokine signaling-1, ICAM-1, and MHC class II proteins. This effect was independent from an increase of STAT1 Tyr or Ser phosphorylation. However, inducible NO synthase expression and NO production decreased under the same conditions. Our results show that Notch up-regulation and subsequent signaling following macrophage activation modulate gene expression patterns known to affect the function of mature macrophages.
Naturally Occurring CD4+Foxp3+ Regulatory T Cells Are an Essential, IL-10-Independent Part of the Immunoregulatory Network inSchistosoma mansoniEgg-Induced Inflammation
Authors: Baumgart Martin , Tompkins Fae , Leng Jin , Hesse Mathias 
Published: April 2014

AbstractIn acute and chronic schistosomiasis, survival of the host requires a carefully balanced immune response against highly immunogenic parasite eggs. We characterized the phenotype, distribution, and functional role of CD4+Foxp3+ naturally occurring regulatory T cells (naTregs) in schistosome egg-induced inflammation. In adoptive transfer experiments and by intracellular staining for Foxp3, we demonstrate significant frequencies of naTregs in hepatic granulomas and draining lymphoid tissues of mice infected with the trematode Schistosoma mansoni. Strikingly, egg-induced inflammation does not change the normal ratio between naTregs and effector CD4+ T cells at the inflammatory site or in lymphoid organs in acute or chronic disease. However, increasing frequencies of CD103-expressing cells in the naTreg compartment indicate a change in phenotype for naTregs with disease progression. Because CD103 was described recently as an activation marker for naTregs, we speculate that naTregs in chronic schistosomiasis are potentially more suppressive. Furthermore, we found that most naTregs do not contribute to egg-induced IL-4 and IL-10 production. Importantly, depletion of CD25+ naTregs strongly enhances the frequency of IL-4-producing effector T cells in acute egg-induced inflammation. It does not change clonal expansion of activated CD4+ T cells. This regulation of egg-induced cytokine production does not require the presence of IL-10. These data demonstrate that naTregs limit egg-induced effector-cytokine production in our model. Our results identify naTregs as an important, IL-10-independent part of the regulatory network in schistosome egg-induced inflammation.
Scanning the HIV Genome for CD4+ T Cell Epitopes Restricted to HLA-DP4, the Most Prevalent HLA Class II Molecule
Authors: Cohen William M. , Pouvelle-Moratille Sandra , Wang Xiao-Fei , Farci Sandrine , Munier Gaetan , Charron Dominique , Ménez André , Busson Marc , Maillère Bernard 
Published: April 2014

AbstractHLA-DP4 alleles are carried by 75% of individuals and are the most frequent HLA II alleles worldwide. Because we have recently characterized the peptide-binding specificity of HLA-DP4 molecules, we developed a peptide-binding prediction method to identify HLA-DP4-restricted peptides in multiple Ags. CD4+ T cell response plays a key role in the immune control of HIV infection, but few HIV-specific T cell epitopes with multi-individual specificity have been identified. They are mostly restricted to HLA-DR molecules, which are very polymorphic molecules. We therefore looked for HLA-DP4-restricted CD4+ T cell epitopes in the whole genome of HIV. Twenty-one peptides were selected from the HXB2 HIV genome based on the prediction of binding to HLA-DP4 molecules. They were submitted to HLA-DP4-binding assays. Seventeen peptides bound to the HLA-DP401 molecule, whereas 15 peptides bound to HLA-DP402. Six peptides bound very tightly to HLA-DP401 and were investigated for their capacity to induce specific CD4+ T cell lines in vitro using dendritic cells and CD4+ T cells collected from eight seronegative HLA-DP4+ donors. Four peptides from env and reverse transcriptase proteins induced in vitro-specific T cell lines restricted to HLA-DP4 molecules. Peptide-induced T cells recognized variants other than the HXB2 sequence and were stimulated by native Ags processed by immature dendritic cells. The reverse transcriptase peptide is present in 65% of the isolated HIV variants. To our knowledge, we describe the first HIV epitopes restricted to HLA-DP4 molecules.
Activation of V(D)J Recombination at the IgH Chain JH Locus Occurs within a 6-Kilobase Chromatin Domain and Is Associated with Nucleosomal Remodeling
Authors: Maës Jérôme , Chappaz Stéphane , Cavelier Patricia , O’Neill Laura , Turner Bryan , Rougeon François , Goodhardt Michele 
Published: April 2014

Abstract
IgH genes are assembled during early B cell development by a series of regulated DNA recombination reactions in which DH and JH segments are first joined followed by VH to DJH rearrangement. Recent studies have highlighted the role of chromatin structure in the control of V(D)J recombination. In this study, we show that, in murine pro-B cell precursors, the JH segments are located within a 6-kb DNase I-sensitive chromatin domain containing acetylated histones H3 and H4, which is delimited 5′ by the DQ52 promoter element and 3′ by the intronic enhancer. Within this domain, the JH segments are covered by phased nucleosomes. High-resolution mapping of nucleosomes reveals that, in pro-B cells, unlike recombination refractory nonlymphoid cells, the recombination signal sequences flanking the four JH segments are located in regions of enhanced micrococcal nuclease and restriction enzyme accessibility, corresponding to either nucleosome-free regions or DNA rendered accessible within a nucleosome. These results support the idea that nucleosome remodeling provides an additional level of control in the regulation of Ig locus accessibility to recombination factors in B cell precursors.
A Role for the MutL Mismatch Repair Mlh3 Protein in Immunoglobulin Class Switch DNA Recombination and Somatic Hypermutation
Authors: Wu Xiaoping , Tsai Connie Y. , Patam Marienida B. , Zan Hong , Chen Jessica P. , Lipkin Steve M. , Casali Paolo 
Published: April 2014

AbstractClass switch DNA recombination (CSR) and somatic hypermutation (SHM) are central to the maturation of the Ab response. Both processes involve DNA mismatch repair (MMR). MMR proteins are recruited to dU:dG mispairs generated by activation-induced cytidine deaminase-mediated deamination of dC residues, thereby promoting S-S region synapses and introduction of mismatches (mutations). The MutL homolog Mlh3 is the last complement of the mammalian set of MMR proteins. It is highly conserved in evolution and is essential to meiosis and microsatellite stability. We used the recently generated knockout mlh3−/− mice to address the role of Mlh3 in CSR and SHM. We found that Mlh3 deficiency alters both CSR and SHM. mlh3−/− B cells switched in vitro to IgG and IgA but displayed preferential targeting of the RGYW/WRCY (R = A or G, Y = C or T, W = A or T) motif by Sγ1 and Sγ3 breakpoints and introduced more insertions and fewer donor/acceptor microhomologies in Sμ-Sγ1 and Sμ-Sγ3 DNA junctions, as compared with mlh3+/+ B cells. mlh3−/− mice showed only a slight decrease in the frequency of mutations in the intronic DNA downstream of the rearranged JH4 gene. However, the residual mutations were altered in spectrum. They comprised a decreased proportion of mutations at dA/dT and showed preferential RGYW/WRCY targeting by mutations at dC/dG. Thus, the MMR Mlh3 protein plays a role in both CSR and SHM.
Triggering of T Cell Activation via CD4 Dimers
Authors: Moldovan Maria-Cristina , Sabbagh Laurent , Breton Gaëlle , Sékaly Rafick-Pierre , Krummel Matthew F. 
Published: April 2014

AbstractThe onset of activation in Th cells is triggered by localized coengagement of TCRs and the coreceptor CD4. A CD4 crystal suggested that CD4 may form dimers in some circumstances. In this study, we use live-cell fluorescence resonance energy transfer imaging to demonstrate that CD4 dimers are present at a basal level on the cell surface and accumulate at the synapse. Mechanistically, we reveal two conditions under which dimers are highly relevant. First, CD4 dimers are more proficient in mediating prolonged cell contacts with APCs in the presence or absence of Ag. This is consistent with a model whereby the dimer functions to increase T-APC avidity. Second, we show that dimer mutations result in an increased level of an inactive lckTyr505 bound to the CD4 molecule relative to dimer-competent CD4. We also find a consistent defect in signaling onset in these cells. This supports a role for CD4 dimerization in maintaining active signaling machinery. We suggest that modulation of the dimer/monomer ratio may permit tuning of activation thresholds during initial engagement.
Replication Initiation from a Novel Origin Identified in the Th2 Cytokine Cluster Locus Requires a Distant Conserved Noncoding Sequence
Authors: Hayashida Toshiro , Oda Masako , Ohsawa Kanako , Yamaguchi Atsumi , Hosozawa Takumi , Locksley Richard M. , Giacca Mauro , Masai Hisao , Miyatake Shoichiro 
Published: April 2014

Abstract
Lineage commitment of Th cells is associated with the establishment of specific transcriptional programs of cytokines. However, how Th cell differentiation affects the program of DNA replication has not been addressed. To gain insight into interplays between differentiation-induced transcription regulation and initiation of DNA replication, we took advantage of an in vitro differentiation system of naive T cells, in which one can manipulate their differentiation into Th1 or Th2 cells. We searched for replication origins in the murine IL-4/IL-13 locus and compared their profiles in the two Th cell lineages which were derived in vitro from the same precursor T cells. We identified a replication origin (oriIL-13) downstream from exon 4 of IL-13 and showed that this origin functions in both Th2 and Th1 cells. A distant regulatory element called CNS-1 (conserved noncoding sequence 1) in the IL-4/IL-13 intergenic region coincides with a Th2-specific DNase I-hypersensitive site and is required for efficient, coordinated expression of Th2 cytokines. Replication initiation from oriIL-13 is significantly reduced in Th1 and Th2 cells derived from CNS-1-deficient mice. However, the replication timing of this locus is consistently early during S phase in both Th1 and Th2 cells under either the wild-type or CNS-1 deletion background. Thus, the conserved noncoding element in the intergenic region regulates replication initiation from a distant replication origin in a manner independent from its effect on lineage-specific transcription but not the replication timing of the segment surrounding this origin.