bluuebunny/crossref_metadata_2025_split huggingface dataset:
Severe Defect in Thymic Development in an Insertional Mutant Mouse Model
Authors: Assarsson Erika , Chambers Benedict J. , Högstrand Kari , Berntman Emma , Lundmark Carin , Fedorova Ludmila , Imreh Stefan , Grandien Alf , Cardell Susanna , Rozell Björn , Ljunggren Hans-Gustaf 
Published: April 2014

Abstract
Transgenic mice were generated expressing NK1.1, an NK cell-associated receptor, under control of the human CD2 promoter. Unexpectedly, one of the founder lines, Tg66, showed a marked defect in thymic development characterized by disorganized architecture and small size. Mapping of the transgene insertion by fluorescence in situ hybridization revealed integration in chromosome 2, band G. Already from postnatal day 3, the thymic architecture was disturbed with a preferential loss of cortical thymic epithelial cells, a feature that became more pronounced over time. Compared with wild-type mice, total thymic cell numbers decreased dramatically between 10 and 20 days of age. Thymocytes isolated from adult Tg66 mice were predominantly immature double-negative cells, indicating a block in thymic development at an early stage of differentiation. Consequently, Tg66 mice had reduced numbers of peripheral CD4+ and CD8+ T cells. Bone marrow from Tg66 mice readily reconstituted thymi of irradiated wild-type as well as RAG-deficient mice. This indicates that the primary defect in Tg66 mice resided in nonhemopoietic stromal cells of the thymus. The phenotype is observed in mice heterozygous for the insertion and does not resemble any known mutations affecting thymic development. Preliminary studies in mice homozygous for transgene insertion reveal a more accelerated and pronounced phenotype suggesting a semidominant effect. The Tg66 mice may serve as a useful model to identify genes regulating thymic epithelial cell differentiation, thymic development, and function.
Autoantigen-B Cell Antigen Receptor Interactions That Regulate Expression of B Cell Antigen Receptor Loci
Authors: Liu Xiaohe , Wysocki Lawrence J. , Manser Tim 
Published: April 2014

AbstractLevels of AgR (BCR) expression are regulated during B cell development, activation, and induction of tolerance. The mechanisms responsible for and consequences of this regulation are poorly understood. We have described a class of DNA-based autoantigen-reactive B cell that down-regulates BCR expression during development to mature follicular phenotype. In this study, we show that at immature stages of primary differentiation, individual B cells of this type can dynamically modulate levels of expression of BCR in inverse proportion to degree of autoantigen engagement and induced BCR signaling. These adjustments in BCR expression are not associated with cell death, BCR revision, or altered development, and do not require TLR 9. Strikingly, modulation of BCR subunit gene RNA levels and transcription parallels these changes in BCR expression, indicating a direct link between autoantigen-BCR interactions of this type and regulation of transcription of BCR-encoding loci. We propose that this adaptive process allows this class of autoreactive B cell to avoid conventional tolerance pathways and promotes development to mature phenotype.
Both the Suppressor of Cytokine Signaling 1 (SOCS-1) Kinase Inhibitory Region and SOCS-1 Mimetic Bind to JAK2 Autophosphorylation Site: Implications for the Development of a SOCS-1 Antagonist
Authors: Waiboci Lilian W. , Ahmed Chulbul M. , Mujtaba Mustafa G. , Flowers Lawrence O. , Martin James P. , Haider Mohammed I. , Johnson Howard M. 
Published: April 2014

Abstract
Suppressor of cytokine signaling (SOCS)-1 protein modulates signaling by IFN-γ by binding to the autophosphorylation site of JAK2 and by targeting bound JAK2 to the proteosome for degradation. We have developed a small tyrosine kinase inhibitor peptide (Tkip) that is a SOCS-1 mimetic. Tkip is compared in this study with the kinase inhibitory region (KIR) of SOCS-1 for JAK2 recognition, inhibition of kinase activity, and regulation of IFN-γ-induced biological activity. Tkip and a peptide corresponding to the KIR of SOCS-1, (53)DTHFRTFRSHSDYRRI(68) (SOCS1-KIR), both bound similarly to the autophosphorylation site of JAK2, JAK2(1001–1013). The peptides also bound to JAK2 peptide phosphorylated at Tyr1007, pJAK2(1001–1013). Dose-response competitions suggest that Tkip and SOCS1-KIR similarly recognize the autophosphorylation site of JAK2, but probably not precisely the same way. Although Tkip inhibited JAK2 autophosphorylation as well as IFN-γ-induced STAT1-α phosphorylation, SOCS1-KIR, like SOCS-1, did not inhibit JAK2 autophosphorylation but inhibited STAT1-α activation. Both Tkip and SOCS1-KIR inhibited IFN-γ activation of Raw 264.7 murine macrophages and inhibited Ag-specific splenocyte proliferation. The fact that SOCS1-KIR binds to pJAK2(1001–1013) suggests that the JAK2 peptide could function as an antagonist of SOCS-1. Thus, pJAK2(1001–1013) enhanced suboptimal IFN-γ activity, blocked SOCS-1-induced inhibition of STAT3 phosphorylation in IL-6-treated cells, enhanced IFN-γ activation site promoter activity, and enhanced Ag-specific proliferation. Furthermore, SOCS-1 competed with SOCS1-KIR for pJAK2(1001–1013). Thus, the KIR region of SOCS-1 binds directly to the autophosphorylation site of JAK2 and a peptide corresponding to this site can function as an antagonist of SOCS-1.
CD8+ T Cell Dysfunction and Increase in Murine Gammaherpesvirus Latent Viral Burden in the Absence of 4-1BB Ligand
Authors: Fuse Shinichiro , Bellfy Sarah , Yagita Hideo , Usherwood Edward J. 
Published: April 2014

Abstract
Studies of costimulatory receptors belonging to the TNFR family have revealed their diverse roles in affecting different stages of the T cell response. The 4-1BB ligand (4-1BBL)/4-1BB pathway has emerged as a receptor-ligand pair that impacts not the initial priming, but later phases of the T cell response, such as sustaining clonal expansion and survival, maintaining memory CD8+ T cells, and supporting secondary expansion upon Ag challenge. Although the role of this costimulatory pathway in CD8+ T cell responses to acute viral infections has been well-studied, its role in controlling chronic viral infections in vivo is not known to date. Using the murine gammaherpesvirus-68 (MHV-68) model, we show that 4-1BBL-deficient mice lack control of MHV-68 during latency and show significantly increased latent viral loads. In contrast to acute influenza infection, the numbers of MHV-68-specific memory CD8+ T cells were maintained during latency. However, the virus-specific CD8+ T cells showed defects in function, including decreased cytolytic function and impaired secondary expansion. Thus, 4-1BBL deficiency significantly affects the function, but not the number, of virus-specific CD8+ T cells during gammaherpesvirus latency, and its absence results in an increased viral burden. Our study suggests that the 4-1BB costimulatory pathway plays an important role in controlling chronic viral infections.
IFN-γ Induces Cysteinyl Leukotriene Receptor 2 Expression and Enhances the Responsiveness of Human Endothelial Cells to Cysteinyl Leukotrienes
Authors: Woszczek Grzegorz , Chen Li-Yuan , Nagineni Sahrudaya , Alsaaty Sara , Harry Anya , Logun Carolea , Pawliczak Rafal , Shelhamer James H. 
Published: April 2014

Abstract
Cysteinyl leukotrienes (cysLTs) are important mediators of cell trafficking and innate immune responses, involved in the pathogenesis of inflammatory processes, i.e., atherosclerosis, pulmonary fibrosis, and bronchial asthma. The aim of this study was to examine the regulation of cysLT signaling by IFN-γ in human primary endothelial cells. IFN-γ increased cysLT receptor 2 (CysLTR2) mRNA expression and CysLTR2-specific calcium signaling in endothelial cells. IFN-γ signaled through Jak/STAT1, as both AG490, a Jak2 inhibitor, and expression of a STAT1 dominant-negative construct, significantly inhibited CysLTR2 mRNA expression in response to IFN-γ. To determine mechanisms of IFN-γ-induced CysLTR2 expression, the human CysLTR2 gene structure was characterized. The CysLTR2 gene has a TATA-less promoter, with multiple transcription start sites. It consists of six variably spliced exons. Eight different CysLTR2 transcripts were identified in endothelial and monocytic cells. Gene reporter assay showed potent basal promoter activity of a putative CysLTR2 promoter region. However, there were no significant changes in gene reporter and mRNA t1/2 assays in response to IFN-γ, suggesting transcriptional control of CysLTR2 mRNA up-regulation by IFN-γ response motifs localized outside of the cloned CysLTR2 promoter region. Stimulation of endothelial cells by cysLTs induced mRNA and protein expression of early growth response genes 1, 2, and 3 and cycloxygenase-2. This response was mediated by CysLTR2 coupled to Gq/11, activation of phospholipase C, and inositol-1,4,5-triphosphate, and was enhanced further 2- to 5-fold by IFN-γ stimulation. Thus, IFN-γ induces CysLTR2 expression and enhances cysLT-induced inflammatory responses.
Knockout of Mkp-1 Enhances the Host Inflammatory Responses to Gram-Positive Bacteria
Authors: Wang Xianxi , Meng Xiaomei , Kuhlman Joshua R. , Nelin Leif D. , Nicol Kathleen K. , English B. Keith , Liu Yusen 
Published: April 2014

Abstract
MAPK phosphatase (MKP)-1 is an archetypal member of the dual specificity protein phosphatase family that dephosphorylates MAPK. We have previously demonstrated that MKP-1 acts as a negative regulator of p38 and JNK in immortalized macrophages after stimulation with peptidoglycan isolated from Gram-positive bacteria. To define the physiological function of MKP-1 during Gram-positive bacterial infection, we studied the innate immune responses to Gram-positive bacteria using Mkp-1 knockout (KO) mice. We found that Mkp-1−/− macrophages exhibited prolonged activation of p38 and JNK, but not of ERK, following exposure to either peptidoglycan or lipoteichoic acid. Compared with wild-type (WT) macrophages, Mkp-1−/− macrophages produced more proinflammatory cytokines such as TNF-α and IL-6. Moreover, after challenge with peptidoglycan, lipoteichoic acid, live or heat-killed Staphylococcus aureus bacteria, Mkp-1 KO mice also mounted a more robust production of cytokines and chemokines, including TNF-α, IL-6, IL-10, and MIP-1α, than did WT mice. Accordingly, Mkp-1 KO mice also exhibited greater NO production, more robust neutrophil infiltration, and more severe organ damage than did WT mice. Surprisingly, WT and Mkp-1 KO mice exhibited no significant difference in either bacterial load or survival rates when infected with live S. aureus. However, in response to challenge with heat-killed S. aureus, Mkp-1 KO mice exhibited a substantially higher mortality rate compared with WT mice. Our studies indicate that MKP-1 plays a critical role in the inflammatory response to Gram-positive bacterial infection. MKP-1 serves to limit the inflammatory reaction by inactivating JNK and p38, thus preventing multiorgan failure caused by exaggerated inflammatory responses.
Amelioration of Experimental Autoimmune Myasthenia Gravis in Rats by Neonatal FcR Blockade
Authors: Liu Liming , Garcia Ana Maria , Santoro Helen , Zhang Yixia , McDonnell Kevin , Dumont Jennifer , Bitonti Alan 
Published: April 2014

Abstract
The neonatal FcR (FcRn) plays a critical role in IgG homeostasis by protecting it from a lysosomal degradation pathway. It has been shown that IgG has an abnormally short half-life in FcRn-deficient mice and that FcRn blockade significantly increases the catabolism of serum IgG in mice. Therefore, reduction of serum IgG half-life may have therapeutic benefits in Ab-mediated autoimmune diseases. We have studied the therapeutic effects of an anti-rat FcRn mAb, 1G3, in two rat models of myasthenia gravis, a prototypical Ab-mediated autoimmune disease. Passive experimental autoimmune myasthenia gravis was induced by administration of an anti-acetylcholine receptor (AChR) mAb, and it was shown that treatment with 1G3 resulted in dose-dependent amelioration of the disease symptoms. In addition, the concentration of pathogenic Ab in the serum was reduced significantly. The effect of 1G3 was also studied in an active model of experimental autoimmune myasthenia gravis in which rats were immunized with AChR. Treatment with 1G3 significantly reduced the severity of the disease symptoms as well as the levels of total IgG and anti-AChR IgG relative to untreated animals. These data suggest that FcRn blockade may be an effective way to treat Ab-mediated autoimmune diseases.
Cutting Edge: Alternative Signaling of Th17 Cell Development by Sphingosine 1-Phosphate
Authors: Liao Jia-Jun , Huang Mei-Chuan , Goetzl Edward J. 
Published: April 2014

Abstract
Sphingosine 1-phosphate (S1P) in blood and lymph controls T cell traffic and proliferation through type 1 S1P receptor (S1P1) signals, but suppression of IFN-γ generation has been the only consistently observed effect on T cell cytokines. The fact that S1P enhances the development of Th17 cells from Ag-challenged transgenic S1P1-overexpressing CD4 T cells suggested that the S1P-S1P1 axis may promote the expansion of Th17 cells in wild-type mice. In a model of Th17 cell development from CD4 T cells stimulated by anti-CD3 plus anti-CD28 Abs and a mixture of TGF-β1, IL-1, and IL-6, S1P enhanced their number and IL-17-generating activity the same as IL-23. As for IL-23 enhancement of Th17 cell development, that by S1P was prevented by IL-4 plus IFN-γ and by IL-27. The prevention of S1P augmentation of Th17 cell development by the S1P receptor agonist and down-regulator FTY720 implies that FTY720 immunosuppression is attributable partially to inhibition of Th17-mediated inflammation.
The Pro-Th1 Cytokine IL-12 Enhances IL-4 Production by Invariant NKT Cells: Relevance for T Cell-Mediated Hepatitis
Authors: Zhu Ren , Diem Séverine , Araujo Luiza M. , Aumeunier Aude , Denizeau Jordan , Philadelphe Emilie , Damotte Diane , Samson Michel , Gourdy Pierre , Dy Michel , Schneider Elke , Herbelin André 
Published: April 2014

Abstract
IL-12 is essential for invariant NKT (iNKT) cells because it can maintain a functionally active population and promote a cytokine profile that is assumed to be mainly of the pro-Th1 type. We used the murine concanavalin A (Con A)-induced hepatitis model, in which iNKT cells, IL-12, IL-4, and IFN-γ are equally requisite, to reevaluate this issue. We demonstrate that IL-12 interacts directly with iNKT cells, contributes to their recruitment to the liver, and enhances their IL-4 production, which is essential for disease onset. IL-12-deficient mice were less susceptible to experimental hepatitis and their iNKT cells produced less IL-4 than their wild-type counterpart. A normal response could be restored by IL-12 injection, revealing its importance as endogenous mediator. In accordance with this observation, we found that iNKT cells expressed the IL-12R constitutively, in contrast to conventional T cells. Furthermore, the physiological relevance of our data is supported by the lower susceptibility to disease induction of NOD mice, known for their inherent functional and numerical abnormalities of iNKT cells associated with decreased iNKT cell-derived IL-4 production and low IL-12 secretion. Taken together, our findings provide the first evidence that IL-12 can enhance the immune response through increased IL-4 production by iNKT cells, underscoring once more the functional plasticity of this subset.
Altering Effects of Antigenic Variations in HIV-1 on Antiviral Effectiveness of HIV-Specific CTLs
Authors: Ueno Takamasa , Idegami Yuka , Motozono Chihiro , Oka Shinichi , Takiguchi Masafumi 
Published: April 2014

Abstract
The mutational escape of HIV-1 from established CTL responses is becoming evident. However, it is not yet clear whether antigenic variations of HIV-1 may have an additional effect on the differential antiviral effectiveness of HIV-specific CTLs. Herein, we characterized HIV-specific CTL responses toward Pol, Env, and Nef optimal epitopes presented by HLA-B*35 during a chronic phase of HIV-1 infection. We found CTL escape variants within Pol and Nef epitopes that affected recognition by TCRs, although there was no mutation within the Env epitope. An analysis of peptide-HLA tetrameric complexes revealed that CD8 T cells exclusively specific for the Nef variant were generated following domination by the variant viruses. The variant-specific cells were capable of killing target cells and producing antiviral cytokines but showed impaired Ag-specific proliferation ex vivo, whereas wild-type specific cells had potent activities. Moreover, clonotypic CD8 T cells specific for the Pol variant showed diminished proliferation, whereas Env-specific ones had no functional heterogeneity. Taken together, our data indicate that antigenic variations that abolished TCR recognition not only resulted in escape from established CTL responses but also eventually generated another subset of variant-specific CTLs having decreased antiviral activity, causing an additional negative effect on antiviral immune responses during a chronic HIV infection.
CD200 Expression on Tumor Cells Suppresses Antitumor Immunity: New Approaches to Cancer Immunotherapy
Authors: Kretz-Rommel Anke , Qin Fenghua , Dakappagari Naveen , Ravey E. Prenn , McWhirter John , Oltean Daniela , Frederickson Shana , Maruyama Toshiaki , Wild Martha A. , Nolan Mary-Jean , Wu Dayang , Springhorn Jeremy , Bowdish Katherine S. 
Published: April 2014

Abstract
Although the immune system is capable of mounting a response against many cancers, that response is insufficient for tumor eradication in most patients due to factors in the tumor microenvironment that defeat tumor immunity. We previously identified the immune-suppressive molecule CD200 as up-regulated on primary B cell chronic lymphocytic leukemia (B-CLL) cells and demonstrated negative immune regulation by B-CLL and other tumor cells overexpressing CD200 in vitro. In this study we developed a novel animal model that incorporates human immune cells and human tumor cells to address the effects of CD200 overexpression on tumor cells in vivo and to assess the effect of targeting Abs in the presence of human immune cells. Although human mononuclear cells prevented tumor growth when tumor cells did not express CD200, tumor-expressed CD200 inhibited the ability of lymphocytes to eradicate tumor cells. Anti-CD200 Ab administration to mice bearing CD200-expressing tumors resulted in nearly complete tumor growth inhibition even in the context of established receptor-ligand interactions. Evaluation of an anti-CD200 Ab with abrogated effector function provided evidence that blocking of the receptor-ligand interaction was sufficient for control of CD200-mediated immune modulation and tumor growth inhibition in this model. Our data indicate that CD200 expression by tumor cells suppresses antitumor responses and suggest that anti-CD200 treatment might be therapeutically beneficial for treating CD200-expressing cancers.
Macrophages and Dendritic Cells Use Different Axl/Mertk/Tyro3 Receptors in Clearance of Apoptotic Cells
Authors: Seitz Heather M. , Camenisch Todd D. , Lemke Greg , Earp H. Shelton , Matsushima Glenn K. 
Published: April 2014

AbstractThe clearance of apoptotic cells is important for regulating tissue homeostasis, inflammation, and autoimmune responses. The absence of receptor tyrosine kinases (Axl, Mertk, and Tyro3) results in widespread accumulation of apoptotic cells and autoantibody production in mice. In this report, we examine the function of the three family members in apoptotic cell clearance by different phagocytic cell types. Mertk elimination nearly abolished macrophage apoptotic cell phagocytosis; elimination of Axl, Tyro3, or both, reduced macrophage phagocytosis by approximately half, indicating that these also play a role. In contrast, apoptotic cell clearance in splenic and bone marrow-derived dendritic cells (DCs) is prolonged compared with macrophages and relied primarily on Axl and Tyro3. The slower ingestion may be due to lower DC expression of Axl and Tyro3 or absence of GAS6 expression, a known ligand for this receptor family. In vivo, phagocytosis of apoptotic material by retinal epithelial cells required Mertk. Unlike macrophages, there did not appear to be any role for Axl or Tyro3 in retinal homeostasis. Likewise, clearance of apoptotic thymocytes in vivo was dramatically reduced in mertkkd mice, but was normal in axl/tyro3−/− mice. Thus, cell and organ type specificity is clearly delineated, with DCs relying on Axl and Tyro3, retina and thymus requiring Mertk, and macrophages exhibiting an interaction that involves all three family members. Surprisingly, in macrophages, tyrosine phosphorylation of Mertk in response to apoptotic cells is markedly diminished from axl/tyro3−/− mice, suggesting that the interactions of these receptors by heterodimerization may be important in some cells.
Plasmid DNA Vaccine-Elicited Cellular Immune Responses Limit In Vivo Vaccine Antigen Expression through Fas-Mediated Apoptosis
Authors: Greenland John R. , Geiben Ralf , Ghosh Sharmistha , Pastor William A. , Letvin Norman L. 
Published: April 2014

Abstract
Particularly potent cellular or humoral immune responses are needed to confer protection in animal models against such pathogens as HIV/SIV, Mycobacterium tuberculosis, and malarial parasites. Persistent, high-level vaccine Ag expression may be required for eliciting such potent and durable immune responses. Although plasmid DNA immunogens are being explored as potential vaccines for protection against these pathogens, little is known about host factors that restrict long-term plasmid DNA vaccine Ag expression in vivo. We observed rapid damping of transgene expression from a plasmid DNA immunogen in wild-type, but not in T cell-deficient mice. This damping of Ag expression was temporally associated with the emergence of Ag-specific cellular immune responses. A requirement for Fas and the appearance of apoptotic nuclei at the site of vaccine inoculation suggest that T cells induce Fas-mediated apoptosis of plasmid DNA vaccine Ag-expressing cells. These studies demonstrate that high levels of in vivo Ag expression are associated with high-frequency cellular immune responses that in turn rapidly down-regulate vaccine Ag expression in vivo. These findings argue that it may not be possible to maintain persistent, high-level production of vaccine Ag in vivo to drive persistent immune responses as long as vaccine Ag production can be limited by host immune responses.