bluuebunny/crossref_metadata_2025_split huggingface dataset:
Basal B Cell Receptor-Directed Phosphatidylinositol 3-Kinase Signaling Turns Off RAGs and Promotes B Cell-Positive Selection
Authors: Verkoczy Laurent , Duong Bao , Skog Patrick , Aït-Azzouzene Djemel , Puri Kamal , Vela José Luis , Nemazee David 
Published: April 2014

Abstract
PI3K plays key roles in cell growth, differentiation, and survival by generating the second messenger phosphatidylinositol-(3,4,5)-trisphosphate (PIP3). PIP3 activates numerous enzymes, in part by recruiting them from the cytosol to the plasma membrane. We find that in immature B lymphocytes carrying a nonautoreactive Ag receptor, PI3K signaling suppresses RAG expression and promotes developmental progression. Inhibitors of PI3K signaling abrogate this positive selection. Furthermore, immature primary B cells from mice lacking the p85α regulatory subunit of PI3K suppress poorly RAG expression, undergo an exaggerated receptor editing response, and, as in BCR-ligated cells, fail to progress into the G1 phase of cell cycle. Moreover, immature B cells carrying an innocuous receptor have sustained elevation of PIP3 levels and activation of the downstream effectors phospholipase C (PLC)γ2, Akt, and Bruton’s tyrosine kinase. Of these, PLCγ2 appears to play the most significant role in down-regulating RAG expression. It therefore appears that when the BCR of an immature B cell is ligated, PIP3 levels are reduced, PLCγ2 activation is diminished, and receptor editing is promoted by sustained RAG expression. Taken together, our results provide evidence that PI3K signaling is an important cue required for fostering development of B cells carrying a useful BCR.
Peritoneal Cell-Derived Mast Cells: An In Vitro Model of Mature Serosal-Type Mouse Mast Cells
Authors: Malbec Odile , Roget Karine , Schiffer Cécile , Iannascoli Bruno , Dumas Antoine Ribadeau , Arock Michel , Daëron Marc 
Published: April 2014

Abstract
Bone marrow-derived mast cells (BMMC) have been used extensively as a mast cell model. BMMC, however, are immature cells that have no known physiological equivalent in tissues. They do not respond to IgG immune complexes. They may therefore not be appropriate for studying the physiopathology of IgE-induced allergies or IgG-induced tissue-specific inflammatory diseases which both depend on mature mast cells. Resident peritoneal mast cells are a minor population of differentiated cells that are not readily purified. They, however, can be expanded in culture to generate large numbers of homogeneous cells. We show here that these peritoneal cell-derived mast cells (PCMC) are mature serosal-type mouse mast cells which retain most morphological, phenotypic, and functional features of peritoneal mast cells. Like peritoneal mast cells, PCMC respond to IgG Abs. IgG immune complex-induced responses depended on FcγRIIIA and were negatively regulated by FcγRIIB. We found that a moderate FcγRIIB-dependent negative regulation, due not to a higher FcγRIIIA/FcγRIIB ratio, but to a relatively inefficient use of the lipid phosphatase SHIP1, determines this property of PCMC. PCMC also respond to IgE Abs. IgE-induced PCMC responses, however, differed quantitatively and qualitatively from BMMC responses. PCMC secreted no or much lower amounts of lipid mediators, chemokines, and cytokines, but they contained and released much higher amounts of preformed granular mediators. PCMC, but not BMMC, also contained and, upon degranulation, released molecules with a potent proteolytic activity. These properties make PCMC a useful new model for understanding the physiopathology of mast cells in IgE- and IgG-dependent tissue inflammation.
Type I Interferon Signaling and B Cells Maintain Hemopoiesis during Pneumocystis Infection of the Lung
Authors: Meissner Nicole , Rutkowski Melanie , Harmsen Ann L. , Han Soo , Harmsen Allen G. 
Published: April 2014

Abstract
Loss of CD4 T cells is the hallmark of HIV infection. However, type I IFN-producing plasmacytoid dendritic cells may also be lost. This results in susceptibility to an opportunistic infection such as Pneumocystis pneumonia. In addition, regenerative bone marrow failure resulting in pancytopenia is another common problem in advanced stage AIDS. This may be linked to both the failing immune system and recurrent opportunistic infections. We generated lymphocyte-deficient type I IFN receptor-deficient mice (IFrag−/−) to study the effects on Pneumocystis infection of the lung. When IFrag−/− animals were infected with Pneumocystis they died between days 16 and 21 postinfection with minimal pneumonia but severe anemia due to complete bone marrow failure. This included the loss of uncommitted hemopoietic precursor cells. Bone marrow failure was prevented by the reconstitution of IFrag−/− mice with wild-type lymphocytes, especially B cells. T and B cells lacking type I IFN receptor signaling could only partially prevent bone marrow failure in response to Pneumocystis infection. However, the presence of T and B cells lacking type I IFN signaling resulted in compensatory extramedullary hemopoiesis in the liver and spleen. Lymphocyte support of the regenerative capacity of the bone marrow was provided by both type I IFN-dependent and -independent mechanisms that acted synergistically. Our findings point to the requirement of both type I IFNs and lymphocytes in the regenerative capabilities of the hemopoietic system under the pressure of Pneumocystis infection, but not during steady-state hemopoiesis. This may have implications in the management of pancytopenia in AIDS.
Cutting Edge: Direct Action of Thymic Stromal Lymphopoietin on Activated Human CD4+ T Cells
Authors: Rochman Irina , Watanabe Norihiko , Arima Kazuhiko , Liu Yong-Jun , Leonard Warren J. 
Published: April 2014

AbstractThymic stromal lymphopoietin (TSLP) is a cytokine that promotes CD4+ T cell homeostasis and contributes to allergic and inflammatory responses. TSLP can act directly on mouse CD4+ T cells, but in humans, the available data have indicated that TSLP receptors are not expressed on CD4+ T cells and that TSLP instead activates dendritic cells, which in turn promote the proliferation and differentiation of CD4+ T cells. We now unexpectedly demonstrate the presence of TSLP receptors on activated human CD4+ T cells. Strikingly, whereas freshly isolated peripheral blood human T cells show little if any response to TSLP, TCR stimulation allows a potent response to this cytokine. Moreover, TSLP increases the sensitivity of human CD4+ T cells to low doses of IL-2, augmenting responsiveness of these cells to TCR engagement. Our results establish that human CD4+ T cells are direct targets for TSLP.
Comparative Prime-Boost Vaccinations Using Semliki Forest Virus, Adenovirus, and ALVAC Vectors Demonstrate Differences in the Generation of a Protective Central Memory CTL Response against the P815 Tumor
Authors: Näslund Tanja I. , Uyttenhove Catherine , Nordström Eva K. L. , Colau Didier , Warnier Guy , Jondal Mikael , Van den Eynde Benoı̂t J. , Liljeström Peter 
Published: April 2014

Abstract
Tumor-specific Ags are potential target molecules in the therapeutic treatment of cancer. One way to elicit potent immune responses against these Ags is to use recombinant viruses, which activate both the innate and the adaptive arms of the immune system. In this study, we have compared Semliki Forest virus (SFV), adenovirus, and ALVAC (poxvirus) vectors for their capacity to induce CD8+ T cell responses against the P1A tumor Ag and to elicit protection against subsequent challenge injection of P1A-expressing P815 tumor cells in DBA/2 mice. Both homologous and heterologous prime-boost regimens were studied. In most cases, both higher CD8+ T cell responses and better tumor protections were observed in mice immunized with heterologous prime-boost regimens, suggesting that the combination of different viral vectors is beneficial for the induction of an effective immune response. However, homologous immunization with SFV provided potent tumor protection despite a rather moderate primary CD8+ T cell response as compared with mice immunized with recombinant adenovirus. SFV-immunized mice showed a rapid and more extensive expansion of P1A-specific CD8+ T cells in the tumor-draining lymph node after tumor challenge and had a higher frequency of CD62L+ P1A-specific T cells in the blood, spleen, and lymph nodes as compared with adenoimmunized mice. Our results indicate that not only the magnitude but in particular the quality of the CD8+ T cell response correlates with tumor protection.
Lack of Essential Role of NF-κB p50, RelA, and cRel Subunits in Virus-Induced Type 1 IFN Expression
Authors: Wang Xingyu , Hussain Sofia , Wang Emilie-Jeanne , Wang Xiuyan , Li Ming O. , García-Sastre Adolfo , Beg Amer A. 
Published: April 2014

Abstract
Type 1 IFNs (IFN-αβ) play pivotal roles in the host antiviral response and in TLR-induced signaling. IFN regulatory factor (IRF) and NF-κB transcription factors are thought to be crucial for virus-induced mRNA expression of IFN-β. Although recent studies have demonstrated essential roles for IRF3 and IRF7, the definitive role of NF-κB factors in IFN-β (or IFN-α) expression remains unknown. Using mice deficient in distinct members of the NF-κB family, we investigated NF-κB function in regulating type 1 IFN expression in response to Sendai virus and Newcastle disease virus infection. Surprisingly, IFN-β and IFN-α expression was strongly induced following virus infection of mouse embryonic fibroblasts (MEFs) from p50−/−, RelA/p65−/−, cRel−/−, p50−/−cRel−/−, and p50−/−RelA−/− mice. Compared with wild-type MEFs, only RelA−/− and p50−/−RelA−/− MEFs showed a modest reduction in IFN-β expression. To overcome functional redundancy between different NF-κB subunits, we expressed a dominant-negative IκBα protein in p50−/−RelA−/− MEFs to inhibit activation of remaining NF-κB subunits. Although viral infection of these cells failed to induce detectable NF-κB activity, both Sendai virus and Newcastle disease virus infection led to robust IFN-β expression. Virus infection of dendritic cells or TLR9-ligand CpG-D19 treatment of plasmacytoid dendritic cells from RelA−/− or p50−/−cRel−/− mice also induced robust type 1 IFN expression. Our findings therefore indicate that NF-κB subunits p50, RelA, and cRel play a relatively minor role in virus-induced type 1 IFN expression.
Th17 Augmentation in OTII TCR Plus T Cell-Selective Type 1 Sphingosine 1-Phosphate Receptor Double Transgenic Mice
Authors: Huang Mei-Chuan , Watson Susan R. , Liao Jia-Jun , Goetzl Edward J. 
Published: April 2014

Abstract
Sphingosine 1-phosphate (S1P) in blood and lymph controls lymphoid traffic and tissue migration of T cells through signals from the type 1 S1PR (S1P1), but less is known of effects of the S1P-S1P1 axis on nonmigration functions of T cells. CD4 T cells from a double transgenic (DTG) mouse express OTII TCRs specific for OVA peptide 323–339 (OVA) and a high level of transgenic S1P1, resistant to suppression by T cell activation. OVA-activated DTG CD4 T cells respond as expected to S1P by chemotactic migration and reduction in secretion of IFN-γ. In addition, DTG CD4 T cells stimulated by OVA secrete a mean of 2.5-fold more IL-17 than those from OTII single transgenic mice with concomitantly higher levels of mRNA encoding IL-17 by real-time PCR and of CD4 T cells with intracellular IL-17 detected by ELISPOT assays. OVA challenge of s.c. air pockets elicited influx of more OTII TCR-positive T cells producing a higher level of IL-17 in DTG mice than OTII control mice. Augmentation of the number and activity of Th17 cells by the S1P-S1P1 axis may thus enhance host defense against microbes and in other settings increase host susceptibility to autoimmune diseases.
Adaptation of TCR Repertoires to Self-Peptides in Regulatory and Nonregulatory CD4+ T Cells
Authors: Wong Jamie , Obst Reinhard , Correia-Neves Margarida , Losyev Grigoriy , Mathis Diane , Benoist Christophe 
Published: April 2014

AbstractCurrently, it is not understood how the specificity of the TCR guides CD4+ T cells into the conventional lineage (Tconv) vs directing them to become regulatory (Treg) cells defined by the Foxp3 transcription factor. To address this question, we made use of the “Limited” (LTD) mouse, which has a restricted TCR repertoire with a fixed TCRβ chain and a TCRα chain minilocus. The TCR repertoires of Tconv and Treg cells were equally broad, were distinct, yet overlapped significantly, representing a less strict partition than previously seen between CD4 and CD8 T cells. As a group, the CDR3α motifs showed a significant trend to higher positive charge in Treg than in Tconv cells. The Tconv and Treg repertoires were both reshaped between thymus and periphery. Reducing the array of peptides presented by MHC class II molecules by introducing the H2-DMo/o mutation into the LTD mouse led to parallel shifts in the repertoires of Tconv and Treg cells. In both cases, the CDR3α elements were entirely different and strikingly shortened, relative to normal LTD mice. These peculiar sequences conferred reactivity to wild-type MHC class II complexes and were excluded from the normal repertoire, even among Treg cells, indicating that some forms of self-reactivity are incompatible with selection into the Treg lineage. In conclusion, the Treg repertoire is broad, with distinct composition and characteristics, yet significantly overlapping and sharing structural constraints with the repertoire of conventional CD4+ T cells.
The Central Leucine-Rich Repeat Region of Chicken TLR16 Dictates Unique Ligand Specificity and Species-Specific Interaction with TLR2
Authors: Keestra A. Marijke , de Zoete Marcel R. , van Aubel Rémon A. M. H. , van Putten Jos P. M. 
Published: April 2014

Abstract
The ligand specificity of human TLR (hTLR) 2 is determined through the formation of functional heterodimers with either hTLR1 or hTLR6. The chicken carries two TLR (chTLR) 2 isoforms, type 1 and type 2 (chTLR2t1 and chTLR2t2), and one putative TLR1/6/10 homologue (chTLR16) of unknown function. In this study, we report that transfection of HeLa cells with the various chicken receptors yields potent NF-κB activation for the receptor combination of chTLR2t2 and chTLR16 only. The sensitivity of this complex was strongly enhanced by human CD14. The functional chTLR16/chTLR2t2 complex responded toward both the hTLR2/6-specific diacylated peptide S-(2,3-bispalmitoyloxypropyl)-Cys-Gly-Asp-Pro-Lys-His-Pro-Lys-Ser-Phe (FSL-1) and the hTLR2/1 specific triacylated peptide tripalmitoyl-S-(bis(palmitoyloxy)propyl)-Cys-Ser-(Lys)3-Lys (Pam3CSK4), indicating that chTLR16 covers the functions of both mammalian TLR1 and TLR6. Dissection of the species specificity of TLR2 and its coreceptors showed functional chTLR16 complex formation with chTLR2t2 but not hTLR2. Conversely, chTLR2t2 did not function in combination with hTLR1 or hTLR6. The use of constructed chimeric receptors in which the defined domains of chTLR16 and hTLR1 or hTLR6 had been exchanged revealed that the transfer of leucine-rich repeats (LRR) 6–16 of chTLR16 into hTLR6 was sufficient to confer dual ligand specificity to the human receptor and to establish species-specific interaction with chTLR2t2. Collectively, our data indicate that diversification of the central LRR region of the TLR2 coreceptors during evolution has put constraints on both their ligand specificity and their ability to form functional complexes with TLR2.
The Neutralization Properties of a HIV-Specific Antibody Are Markedly Altered by Glycosylation Events Outside the Antigen-Binding Domain
Authors: Miranda Luis R. , Duval Mark , Doherty Heather , Seaman Michael S. , Posner Marshall R. , Cavacini Lisa A. 
Published: April 2014

Abstract
Neutralizing Abs constitute a pivotal mechanism of the adaptive immune response against HIV-1 infection. Yet, most of the Abs that appear in the circulation during HIV infection are nonneutralizing. In this study, we report a dramatic change of the neutralizing properties of a human Ab reactive with the nonneutralizing epitope termed cluster I on the HIV-1 transmembrane protein gp41 when the Ab was produced in Chinese hamster ovary (CHO)-K1 cells. Our laboratory has previously reported that the Ab F240, when produced in a hybridoma, is nonneutralizing as assessed by standard neutralization assays. The F240 IgG1 Ab expressed in CHO cells acquired a strong neutralization activity against a broad range of HIV isolates without a change in immunoreactivity. Sequencing of the F240 mRNAs produced in the parental hybridoma and CHO cells revealed identical sequences, suggesting that acquired neutralization resulted from cell-specific posttranslational modifications. We found that the Ab produced by CHO cells is glycosylated to a greater extent than the parental Ab produced by the hybridoma. Moreover, treatment with peptide N-glycosidase F abrogated F240 neutralization, in an isolate-specific manner, but not Ab b12 neutralization. Interestingly, the F240 isotype-switched variants IgG3 and IgG4, also expressed in CHO cells, exhibited identical immunoreactivity to IgG1 isotypes but had clear differences in viral neutralization. These results suggest that structural features of the Ig molecule other than the primary sequence of the variable regions play a more prominent role in HIV neutralization than anticipated.
Defining In Vivo Transcription Factor Complexes of the Murine CD21 and CD23 Genes
Authors: Debnath Irina , Roundy Kirstin M. , Weis Janis J. , Weis John H. 
Published: April 2014

AbstractThe expression of the CD21 and CD23 genes is coincident with differentiation from transition 1 B cells (T1) to transition 2 B cells (T2). To define constituents controlling CD21 and CD23 expression, we conducted chromatin immunoprecipitation analyses for candidate transcription factors. We found constitutive binding of Oct-1, NFAT species, YY1, NF-κB-p52, Pax5, E2A, and RBP-Jκ to CD21 sequences and NF-κB-p52, Pax5, NFAT species, E2A, and RBP-Jκ to CD23 promoter sequences. Splenic T and B cell subsets displayed constitutive binding of YY1, NF-κB-p52, Pax5, and Oct-1 proteins to CD21 sequences in B cells but no specific binding of NFATc3 or Pax5 in T cells. Similarly, CD23 sequences demonstrated constitutive binding of NF-κB-p52 in splenic T and B cells but only Pax5 in B cells. Of the various NFAT species, only a subset were found forming constitutive DNA/protein complexes with the CD21, CD23, and IL-2 gene sequences. Maturing B cells in the marrow possess stable Pax5 complexes on CD19, CD21, and CD23 gene promoters in the nuclei of such cells, even though only CD19 is expressed. The similarity of genetic controlling elements between the CD21 and CD23 genes does not suggest a mechanism for alternative regulation of these genes; however, separation of splenic B cell subsets into T1, T2, marginal zone (MZ), and mature follicular B cells, followed by quantitative RT-PCR, demonstrated the lack of appreciable CD23 transcripts in CD21+ MZ cells. We propose an alternative derivation of MZ cells as maturing directly from T1 cells, leaving CD23 transcriptionally inactive in that lineage of cells.
Genomics and Diversity of the Common Marmoset Monkey NK Complex
Authors: Averdam Anne , Kuhl Heiner , Sontag Mario , Becker Tamara , Hughes Austin L. , Reinhardt Richard , Walter Lutz 
Published: April 2014

Abstract
The common marmoset monkey (Callithrix jacchus) is a New World primate that is increasingly used in biomedical research as a model organism. Due to the occurrence of natural bone marrow chimerism, it represents a particularly useful primate model in immunological research. In this study, we describe the genomic organization of the CD94, NKG2, and LY49L genes in the NK complex (NKC) of the common marmoset based on complete sequencing of a bacterial artificial chromosome clonal contig. This region of the marmoset NKC is 1.5 times smaller than its human counterpart, but the genes are colinear and orthologous. One exception is the activating NKG2CE gene, which is probably an ancestral form of the NKG2C- and NKG2E-activating receptor genes of humans and great apes. The two completely sequenced marmoset bacterial artificial chromosome clones are derived from distinct haplotypes, which differ by 200 sites in the overlapping sequence. Analyses of NKC genes in nine additional marmoset individuals revealed a moderate degree of polymorphism of the CD94, NKG2A, NKG2CE, and NKG2D genes. Furthermore, expression analyses identified several alternatively spliced transcripts, particularly of the CD94 gene. Several products of alternative splicing of NKC genes are highly conserved among primates. Alternative transcriptional start sites were found, but these probably do not lead to a change of the translational start site or result in longer or shorter cytoplasmic regions of these type II membrane receptors.
Extended Gene Map Reveals Tripartite Motif, C-Type Lectin, and Ig Superfamily Type Genes within a Subregion of the Chicken MHC-B Affecting Infectious Disease
Authors: Shiina Takashi , Briles W. Elwood , Goto Ronald M. , Hosomichi Kazuyoshi , Yanagiya Kazuyo , Shimizu Sayoko , Inoko Hidetoshi , Miller Marcia M. 
Published: April 2014

Abstract
MHC haplotypes have a remarkable influence on whether tumors form following infection of chickens with oncogenic Marek’s disease herpesvirus. Although resistance to tumor formation has been mapped to a subregion of the chicken MHC-B region, the gene or genes responsible have not been identified. A full gene map of the subregion has been lacking. We have expanded the MHC-B region gene map beyond the 92-kb core previously reported for another haplotype revealing the presence of 46 genes within 242 kb in the Red Jungle Fowl haplotype. Even though MHC-B is structured differently, many of the newly revealed genes are related to loci typical of the MHC in other species. Other MHC-B loci are homologs of genes found within MHC paralogous regions (regions thought to be derived from ancient duplications of a primordial immune defense complex where genes have undergone differential silencing over evolutionary time) on other chromosomes. Still others are similar to genes that define the NK complex in mammals. Many of the newly mapped genes display allelic variability and fall within the MHC-B subregion previously shown to affect the formation of Marek’s disease tumors and hence are candidates for genes conferring resistance.
Viral Interference with Antigen Presentation Does Not Alter Acute or Chronic CD8 T Cell Immunodominance in Murine Cytomegalovirus Infection
Authors: Munks Michael W. , Pinto Amelia K. , Doom Carmen M. , Hill Ann B. 
Published: April 2014

Abstract
Both human CMV and murine CMV (MCMV) elicit large CD8 T cell responses, despite the potent effects of viral genes that interfere with the MHC class I (MHC I) pathway of Ag presentation. To investigate the impact of immune evasion on CD8 T cell priming, we infected mice with wild-type (wt) MCMV or a mutant lacking its MHC I immune evasion genes, Δm4+m6+m152 MCMV. In acute infection, the two viruses elicited a CD8 T cell response to 26 peptide epitopes that was virtually identical in total size, kinetics, and immunodominance hierarchy. This occurred despite results demonstrating that primary DCs are susceptible to the effects of MCMV’s MHC I immune evasion genes. Eight months later, responses to both wt and mutant MCMV displayed the same CD8 T cell “memory inflation” and altered immunodominance that characterize the transition to chronic MCMV infection in C57BL/6 mice. Taken together, these findings suggest either that cross-priming dominates over direct CD8 T cell priming in both acute and chronic MCMV infection, or else that the MHC I immune evasion genes of MCMV are unable to alter direct CD8 T cell priming in vivo. At 2 years postinfection, differences in CD8 T cell immunodominance emerged between individual mice, but on average there were only slight differences between wt and mutant virus infections. Overall, the data indicate that the presence or absence of MHC I immune evasion genes has remarkably little impact on the size or specificity of the MCMV-specific CD8 T cell response over an entire lifetime of infection.