bluuebunny/crossref_metadata_2025_split huggingface dataset:
Islet Allograft Rejection in Nonobese Diabetic Mice Involves the Common γ-Chain and CD28/CD154-Dependent and -Independent Mechanisms
Authors: Demirci Gulcin , Strom Terry B. , Li Xian Chang 
Published: April 2014

AbstractOnce nonobese diabetic (NOD) mice become diabetic, they are highly resistant to islet transplantation. The precise mechanism of such resistance remains largely unknown. In the present study we tested the hypothesis that islet allograft survival in the diabetic NOD mouse is determined by the interplay of diverse islet-specific T cell subsets whose activation is regulated by CD28/CD154 costimulatory signals and the common γ-chain (γc; a shared signaling element by receptors for IL-2, IL-4, IL-7, IL-9, IL-15, and IL-21). We found that common γc blockade is remarkably effective in blocking the onset and the ongoing autoimmune diabetes, whereas CD28/CD154 blockade has no effect in suppressing the ongoing diabetes. However, CD28/CD154 blockade completely blocks the alloimmune-mediated islet rejection. Also, a subset of memory-like T cells in the NOD mice is resistant to CD28/CD154 blockade, but is sensitive to the common γc blockade. Nonetheless, neither common γc blockade nor CD28/CD154 blockade can prevent islet allograft rejection in diabetic NOD mice. Treatment of diabetic NOD recipients with CD28/CD154 blockade plus γc blockade markedly prolongs islet allograft survival compared with the controls. However, allograft tolerance is not achieved, and all CTLA-4Ig-, anti-CD154-, and anti-γc-treated diabetic NOD mice eventually rejected the islet allografts. We concluded that the effector mechanisms in diabetic NOD hosts are inherently complex, and rejection in this model involves CD28/CD154/γc-dependent and -independent mechanisms.
Cutting Edge: Cyclooxygenase-2 Activation Suppresses Th1 Polarization in Response toHelicobacter pylori
Authors: Meyer Frank , Ramanujam Kalathur S. , Gobert Alain P. , James Stephen P. , Wilson Keith T. 
Published: April 2014

AbstractHelicobacter pylori infection causes a Th1-driven mucosal immune response. Cyclooxygenase (COX)-2 is up-regulated in lamina propria mononuclear cells in H. pylori gastritis. Because COX-2 can modulate Th1/Th2 balance, we determined whether H. pylori activates COX-2 in human PBMCs, and the effect on cytokine and proliferative responses. There was significant up-regulation of COX-2 mRNA and PGE2 release in response to H. pylori preparations. Addition of COX-2 inhibitors or an anti-PGE2 Ab resulted in a marked increase in H. pylori-stimulated IL-12 and IFN-γ production, and a decrease in IL-10 levels. Addition of PGE2 or cAMP, the second messenger activated by PGE2, had the opposite effect. Similarly, stimulated cell proliferation was increased by COX-2 inhibitors or anti-PGE2 Ab, and was decreased by PGE2. Our findings indicate that COX-2 has an immunosuppressive role in H. pylori gastritis, which may protect the mucosa from severe injury, but may also contribute to the persistence of the infection.
Clonal Expansion of Double-Positive Intraepithelial Lymphocytes by MHC Class I-Related Chain A Expressed in Mouse Small Intestinal Epithelium
Authors: Park Eun Jeong , Takahashi Ichiro , Ikeda Junko , Kawahara Kazuko , Okamoto Tetsuji , Kweon Mi-Na , Fukuyama Satoshi , Groh Veronika , Spies Thomas , Obata Yuichi , Miyazaki Jun-Ichi , Kiyono Hiroshi 
Published: April 2014

AbstractExpression of a distant homologue MHC class I molecule, MHC class I-related chain A (MICA), has been found to be stress inducible and limited to the intestinal epithelium. This nonclassical MHC molecule is associated with various carcinomas in humans. To understand the biological consequences of MICA expression in the gut, we generated transgenic (Tg) mice (T3b-MICA Tg) under the control of the T3b promoter. The T3b-MICA Tg mice expressed MICA selectively in the intestine and had an increased number of TCRαβ CD4CD8αα, double-positive (DP) intraepithelial lymphocytes (IELs) in the small bowel. These MICA-expanded DP IELs exhibited a bias to Vβ8.2 and overlapped motifs of the complementarity-determining region 3 region among various Tg mice. Hence, the overexpression of MICA resulted in a clonal expansion of DP IELs. Studies in model of inflammatory bowel disease showed that transgenic MICA was able to attenuate the acute colitis induced by dextran sodium sulfate administration. Therefore, this unique in vivo model will enable investigation of possible influences of stress-inducible MICA on the gut immune surveillance.
The Rac-Activating Toxin Cytotoxic Necrotizing Factor 1 Oversees NK Cell-Mediated Activity by Regulating the Actin/Microtubule Interplay
Authors: Malorni W. , Quaranta M. G. , Straface E. , Falzano L. , Fabbri A. , Viora M. , Fiorentini C. 
Published: April 2014

Abstract
The cell cytoskeleton is widely acknowledged as a master for NK cell function. Specifically, actin filaments guide the NK cell binding to target cells, engendering the formation of the so-called immunological synapse, while microtubules direct the killer behavior. All these cytoskeleton-dependent activities are competently governed by the Rho GTPases, a family of regulatory molecules encompassing the three different subfamilies, Rho, Rac, and Cdc42. By using a Rac GTPase-activating bacterial protein toxin from Escherichia coli named cytotoxic necrotizing factor 1 (CNF1), we obtained results supporting the activation of Rac GTPase as a booster for effector cell-binding efficiency, recruitment ability, and, consequently, cytotoxicity. In particular, the augmented killer capacity of CNF1-treated NK cells was associated with the increased expression of certain cell adhesion or activation-associated molecules and the reshaping of the actin and microtubule networks. Importantly, CNF1 counteracted the activity exerted by toxins disrupting the cytoskeletal architecture. Hence, the activation of Rho GTPases, particularly Rac, induced by CNF1, appears to orchestrate a dynamic cross talk between microtubules and actin filaments, leading to a fruitful NK cell activity and polarization state. Our findings suggest that protein toxins might be viewed as modulators of NK cell cytotoxic activity and could possibly be regarded as useful pharmacological tools for certain Rho-linked immune diseases in the near future.
NF-κB RegulatesBCL3Transcription in T Lymphocytes Through an Intronic Enhancer
Authors: Ge Baosheng , Li Olga , Wilder Phillip , Rizzino Angie , McKeithan Timothy W. 
Published: April 2014

AbstractExposure to soluble protein Ags in vivo leads to abortive proliferation of responding T cells. In the absence of a danger signal, artificially provided by adjuvants, most responding cells die, and the remainder typically become anergic. The adjuvant-derived signals provided to T cells are poorly understood, but recent work has identified BCL3 as the gene, of those tested, with the greatest differential transcriptional response to adjuvant administration in vivo. As an initial step in analyzing transcriptional responses of BCL3 in T cells, we have identified candidate regulatory regions within the locus through their evolutionary conservation and by analysis of DNase hypersensitivity. An evolutionarily conserved DNase hypersensitive site (HS3) within intron 2 was found to act as a transcriptional enhancer in response to stimuli that mimic TCR activation, namely, PHA and PMA. In luciferase reporter gene constructs transiently transfected into the Jurkat T cell line, the HS3 enhancer can cooperate not only with the BCL3 promoter, but also with an exogenous promoter from herpes simplex thymidine kinase. Deletional analysis revealed that a minimal sequence of ∼81 bp is required for full enhancer activity. At the 5′ end of this minimal sequence is a κB site, as confirmed by EMSAs. Mutation of this site in the context of the full-length HS3 abolished enhancer activity. Cotransfection with NF-κB p65 expression constructs dramatically increased luciferase activity, even without stimulation. Conversely, cotransfection with the NF-κB inhibitor IκBα reduced activation. Together, these results demonstrate a critical role for NF-κB in BCL3 transcriptional up-regulation by TCR-mimetic signals.
Transcriptional Control of MurineCD94Gene: Differential Usage of Dual Promoters by Lymphoid Cell Types
Authors: Wilhelm Brian T. , Landry Josette-Renée , Takei Fumio , Mager Dixie L. 
Published: April 2014

AbstractThe CD94 gene product is involved in controlling NK cell activation, and is one of a family of immune receptors that is found in the NK gene complex in both humans and mice, adjacent to members of the NKG2 family. CD94 forms a heterodimeric complex with several members of the NKG2 family on the surface of NK, T, and NKT cells. These complexes recognize the nonclassical MHC class I molecules HLA-E and Qa-1b in humans and mice, respectively. The mechanism for cell type-specific expression of CD94 and other genes from the NK gene complex has not yet been elucidated. In the current study, we show that the murine CD94 gene has two promoters, one of which is upstream of a previously unidentified exon. We illustrate by quantitative real-time PCR that lymphoid cell types use these two promoters differentially and that the promoter usage seen in adult cells is already established during fetal development. We determined that the differential promoter usage by NK cells appears to be susceptible to perturbation, as both the murine NK cell line LNK, as well as cultured C57BL/6 NK cells showed altered promoter usage relative to fresh NK cells. Furthermore, the promoter activity observed in transfection assays did not correlate with expression of the endogenous CD94 gene, suggesting the involvement of chromatin structure/methylation in transcriptional regulation. Our detection of DNase I hypersensitive sites at the CD94 locus that are present only in a cell line expressing endogenous CD94 supports this hypothesis.
Blockade of Airway Inflammation and Hyperresponsiveness by HIV-TAT-Dominant Negative Ras
Authors: Myou Shigeharu , Zhu Xiangdong , Myo Saori , Boetticher Evan , Meliton Angelo Y. , Liu Jie , Munoz Nilda M. , Leff Alan R. 
Published: April 2014

AbstractWe have reported previously that HIV-TAT-dominant negative (dn) Ras inhibits eosinophil adhesion to ICAM-1 after activation by IL-5 and eotaxin. In this study, we evaluated the role of Ras in Ag-induced airway inflammation and hyperresponsiveness by i.p. administration into mice of dnRas, which was fused to an HIV-TAT protein transduction domain (TAT-dnRas). Uptake of TAT-dnRas (t1/2 = 12 h) was demonstrated in leukocytes after i.p. administration. OVA-sensitization significantly increased eosinophil and lymphocyte numbers in bronchoalveolar lavage fluid 24 h after final challenge. Treatment of animals with 3–10 mg/kg TAT-dnRas blocked the migration of eosinophils from 464 ± 91 × 103/ml to 288 ± 79 × 103/ml with 3 mg/kg of TAT-dnRas (p &lt; 0.05), and further decreased to 116 ± 63 × 103/ml after 10 mg/kg TAT-dnRas (p &lt; 0.01). Histological examination demonstrated that inflammatory cell infiltration (largely eosinophils and mononuclear cells) and mucin production around the airways caused by OVA were blocked by TAT-dnRas. OVA challenge also caused airway hyperresponsiveness to methacholine, which was dose dependently blocked by treatment with TAT-dnRas. TAT-dnRas also blocked Ag-induced IL-4 and IL-5, but not IFN-γ, production in lung tissue. Intranasal administration of IL-5 caused eosinophil migration into the airway lumen, which was attenuated by pretreatment with TAT-dnRas. By contrast, TAT-green fluorescent protein or dnRas lacking the TAT protein transduction domain did not block airway inflammation, cytokine production, or airway hyperresponsiveness. We conclude that Ras mediates Th2 cytokine production, airway inflammation, and airway hyperresponsiveness in immune-sensitized mice.
IL-8/CXCL8 and Growth-Related Oncogene α/CXCL1 Induce Chondrocyte Hypertrophic Differentiation
Authors: Merz Denise , Liu Ru , Johnson Kristen , Terkeltaub Robert 
Published: April 2014

AbstractFoci of chondrocyte hypertrophy that commonly develop in osteoarthritic (OA) cartilage can promote dysregulated matrix repair and pathologic calcification in OA. The closely related chemokines IL-8/CXCL8 and growth-related oncogene α (GROα)/CXCL1 and their receptors are up-regulated in OA cartilage chondrocytes. Because these chemokines regulate leukocyte activation through p38 mitogen-activated protein kinase signaling, a pathway implicated in chondrocyte hypertrophic differentiation, we tested whether IL-8 and GROα promote chondrocyte hypertrophy. We observed that normal human and bovine primary articular chondrocytes expressed both IL-8Rs (CXCR1, CXCR2). IL-8 and the selective CXCR2 ligand GROα (10 ng/ml) induced tissue inhibitor of metalloproteinase-3 expression, markers of hypertrophy (type X collagen and MMP-13 expression, alkaline phosphatase activity), as well as matrix calcification. IL-8 and the selective CXCR2 ligand GROα also induced increased transamidation activity of chondrocyte transglutaminases (TGs), enzymes up-regulated in chondrocyte hypertrophy that have the potential to modulate differentiation and calcification. Under these conditions, p38 mitogen-activated protein kinase pathway signaling mediated induction of both type X collagen and TG activity. Studies using mouse knee chondrocytes lacking one of the two known articular chondrocyte-expressed TG isoenzymes (TG2) demonstrated that TG2 was essential for murine GROα homologue KC-induced TG activity and critically mediated induction by KC of type X collagen, matrix metalloproteinase-13, alkaline phosphatase, and calcification. In conclusion, IL-8 and GROα induce articular chondrocyte hypertrophy and calcification through p38 and TG2. Our results suggest a novel linkage between inflammation and altered differentiation of articular chondrocytes. Furthermore, CXCR2 and TG2 may be sites for intervention in the pathogenesis of OA.
Thymocyte Sensitivity and Supramolecular Activation Cluster Formation Are Developmentally Regulated: A Partial Role for Sialylation
Authors: Starr Timothy K. , Daniels Mark A. , Lucido Michelle M. , Jameson Stephen C. , Hogquist Kristin A. 
Published: April 2014

Abstract
TCR reactivity is tuned during thymic development. Immature thymocytes respond to low-affinity self-ligands resulting in positive selection. Following differentiation, T cells no longer respond to low-affinity ligands, but respond well to high-affinity (foreign) ligands. We show in this study that this response includes integrin activation, supramolecular activation cluster formation, Ca2+ flux, and CD69 expression. Because glycosylation patterns are known to change during T cell development, we tested whether alterations in sialylation influence CD8 T cell sensitivity to low affinity TCR ligands. Using neuraminidase treatment or genetic deficiency in the ST3Gal-I sialyltransferase, we show that desialylation of mature CD8 T cells enhances their sensitivity to low-affinity ligands, although these treatments do not completely recapitulate the dynamic range of immature T cells. These studies identify sialylation as one of the factors that regulate CD8 T cell tuning during development.
CD8+αβ+ T Cells That Lack Surface CD5 Antigen Expression Are a Major Lymphotactin (XCL1) Source in Peripheral Blood Lymphocytes
Authors: Stievano Laura , Tosello Valeria , Marcato Novella , Rosato Antonio , Sebelin Annalisa , Chieco-Bianchi Luigi , Amadori Alberto 
Published: April 2014

Abstract
To better characterize the cellular source of lymphotactin (XCL1), we compared XCL1 expression in different lymphocyte subsets by real-time PCR. XCL1 was constitutively expressed in both PBMC and CD4+ cells, but its expression was almost 2 log higher in CD8+ cells. In vitro activation was associated with a substantial increase in XCL1 expression in both PBMC and CD8+ cells, but not in CD4+ lymphocytes. The preferential expression of XCL1 in CD8+ cells was confirmed by measuring XCL1 production in culture supernatants, and a good correlation was found between figures obtained by real-time PCR and XCL1 contents. XCL1 expression was mostly confined to a CD3+CD8+ subset not expressing CD5, where XCL1 expression equaled that shown by γδ+ T cells. Compared with the CD5+ counterpart, CD3+CD8+CD5− cells, which did not express CD5 following in vitro activation, showed preferential expression of the αα form of CD8 and a lower expression of molecules associated with a noncommitted/naive phenotype, such as CD62L. CD3+CD8+CD5− cells also expressed higher levels of the XCL1 receptor; in addition, although not differing from CD3+CD8+CD5+ cells in terms of the expression of most α- and β-chemokines, they showed higher expression of CCL3/macrophage inflammatory protein-1α. These data show that TCR αβ-expressing lymphocytes that lack CD5 expression are a major XCL1 source, and that the contribution to its synthesis by different TCR αβ-expressing T cell subsets, namely CD4+ lymphocytes, is negligible. In addition, they point to the CD3+CD8+CD5− population as a particular T cell subset within the CD8+ compartment, whose functional properties deserve further attention.
Another View of T Cell Antigen Recognition: Cooperative Engagement of Glycolipid Antigens by Va14Ja18 Natural TCR
Authors: Stanic Aleksandar K. , Shashidharamurthy R. , Bezbradica Jelena S. , Matsuki Naoto , Yoshimura Yoshitaka , Miyake Sachiko , Choi Eun Young , Schell Todd D. , Van Kaer Luc , Tevethia Satvir S. , Roopenian Derry C. , Yamamura Takashi , Joyce Sebastian 
Published: April 2014

Abstract
Va14Ja18 natural T (iNKT) cells rapidly elicit a robust effector response to different glycolipid Ags, with distinct functional outcomes. Biochemical parameters controlling iNKT cell function are partly defined. However, the impact of iNKT cell receptor β-chain repertoire and how α-galactosylceramide (α-GalCer) analogues induce distinct functional responses have remained elusive. Using altered glycolipid ligands, we discovered that the Vb repertoire of iNKT cells impacts recognition and Ag avidity, and that stimulation with suboptimal avidity Ag results in preferential expansion of high-affinity iNKT cells. iNKT cell proliferation and cytokine secretion, which correlate with iNKT cell receptor down-regulation, are induced within narrow biochemical thresholds. Multimers of CD1d1-αGalCer- and αGalCer analogue-loaded complexes demonstrate cooperative engagement of the Va14Ja18 iNKT cell receptor whose structure and/or organization appear distinct from conventional αβ TCR. Our findings demonstrate that iNKT cell functions are controlled by affinity thresholds for glycolipid Ags and reveal a novel property of their Ag receptor apparatus that may have an important role in iNKT cell activation.
Translational Control of Inducible Nitric Oxide Synthase by IL-13 and Arginine Availability in Inflammatory Macrophages
Authors: El-Gayar Stefan , Thüring-Nahler Heike , Pfeilschifter Josef , Röllinghoff Martin , Bogdan Christian 
Published: April 2014

AbstractInducible NO synthase (iNOS) and its generation of NO from l-arginine are subject to transcriptional as well as posttranscriptional control by cytokines. In this study, we describe a novel, translational mechanism of iNOS regulation by arginine availability. Using mouse inflammatory peritoneal macrophages stimulated with IFN-γ plus LPS, we demonstrate that the suppression of iNOS protein, which is observed after a 16-h (but not after a 6-h) pretreatment with IL-13, despite an unaltered iNOS mRNA level, results from arginine depletion by arginase. The addition of arginase inhibitors (in the pretreatment phase) or of arginine (in the stimulation phase) completely blocked the down-regulation of iNOS protein by IL-13. The rescuing effect of arginine supplementation was not due to a positive feedback regulation of iNOS expression via enhanced production of NO. A striking suppression of iNOS protein (but not of iNOS mRNA) was also seen, when IL-13 was replaced by purified arginase or when macrophages were stimulated with IFN-γ/LPS in arginine-free medium. Arginine deficiency specifically impaired the de novo synthesis and the stability of iNOS protein, but did not affect the production of TNF and the overall protein synthesis of the macrophages. From these results, we conclude that arginine not only functions as a substrate for iNOS, but is also critical for maintaining normal levels of iNOS protein in cytokine-stimulated macrophages.
CD40 Stimulation of Human Peripheral B Lymphocytes: Distinct Response from Naive and Memory Cells
Authors: Fecteau Jessie F. , Néron Sonia 
Published: April 2014

AbstractDuring secondary immune response, memory B lymphocytes proliferate and differentiate into Ig-secreting cells. In mice, the binding of CD40 by CD154 clearly enhances the activation and differentiation of memory B lymphocytes. In humans, the role of CD40-CD154 in the stimulation of memory B lymphocytes is not as obvious since in vitro studies reported positive and negative effects on their proliferation and differentiation in Ig-secreting cells. In this study, we examine the response of peripheral memory and naive cells in relation to the duration of CD40-CD154 interaction. We measured the proliferation and differentiation of both subsets stimulated with CD154 and IL-4 for short- (4–5 days) and long-term (&gt;7 days) periods. Following short-term stimulation, memory B lymphocytes did not expand but represented the only subset differentiating into IgG- and IgM-secreting cells. A longer stimulation of this population led to cell death, while promoting naive B lymphocyte proliferation, expansion, and differentiation into IgM- or IgG-secreting cells. This prolonged CD40 stimulation also triggered naive B lymphocytes to switch to IgG and to express CD27 even in absence of somatic hypermutation, suggesting that these latter events could be independent. This study suggests that naive and memory B lymphocytes have distinct requirements to engage an immune response, reflecting their different roles in humoral immunity.
Estimating Hypermutation Rates from Clonal Tree Data
Authors: Kleinstein Steven H. , Louzoun Yoram , Shlomchik Mark J. 
Published: April 2014

Abstract
To understand the mechanisms underlying the varying patterns of mutations that occur during immune and autoimmune responses, estimates of the somatic hypermutation rate are critical. However, despite its significance, precise estimates of the mutation rate do not currently exist. Microdissection studies of mutating B cell clones provide an opportunity to measure this rate more accurately than previously possible. Each microdissection provides a number of clonally related sequences that, through the analysis of shared mutations, can be genealogically related to each other. The shape of these clonal trees is influenced by many processes, including the hypermutation rate. We have developed two different methods to estimate the mutation rate based on these data. These methods are applied to two sets of experimental data, one from an autoimmune response and one from the antihapten response to (4-hydroxy-3-nitrophenyl)acetyl (NP). Comparable mutation rates are estimated for both responses, 0.7–0.9 × 10−3 and 0.9–1.1 × 10−3 bp−1 division−1 for the autoimmune and NP responses, respectively. In addition to comparing the results of the two procedures, we investigate the effect on our estimate of assumptions, such as the fraction of lethal mutations.