bluuebunny/crossref_metadata_2025_split huggingface dataset:
Redundancy in B Cell Developmental Pathways: c-Cbl Inactivation Rescues Early B Cell Development through a B Cell Linker Protein-Independent Pathway
Authors: Song Haifeng , Zhang Juan , Chiang Y. Jeffrey , Siraganian Reuben P. , Hodes Richard J. 
Published: April 2014

Abstract
Deficiency in the adaptor protein B cell linker protein (BLNK) results in a substantial but incomplete block in B cell development, suggesting that alternative pathways exist for B lineage differentiation. Another adaptor protein, c-Cbl, plays a negative regulatory role in several BCR-signaling pathways. We therefore investigated the role of c-Cbl during B cell development and addressed the possibility that redundancies in pathways for B cell differentiation could be further revealed by eliminating negative effects mediated by c-Cbl. Strikingly, c-Cbl inactivation reversed a number of the critical defects in early B cell differentiation that are seen in BLNK-deficient mice. c-Cbl−/−BLNK−/− mice exhibited normalized down-regulation of pre-BCR and CD43, up-regulation of MHC class II, and augmented L chain rearrangement, resulting in a successful transition from pre-B cells to immature B cells. c-Cbl inactivation also reversed the potentially tumor-predisposing hyperproliferative response of BLNK−/− pre-B cells to IL-7. Pre-BCR cross-linking induced enhanced and prolonged tyrosine phosphorylation in c-Cbl−/−BLNK−/− pre-BCR+ pre-B cells compared with c-Cbl+/−BLNK−/− cells, including elevated phosphorylation of Lyn, Syk, Btk, and phospholipase C-γ2. Our studies suggest that some, but not all, pre-BCR-triggered developmental events can be mediated by BLNK-independent pathways that are negatively regulated by c-Cbl, and further suggest that different events during early B cell development require different strength or duration of pre-BCR signaling.
First Glimpse of the Peptide Presentation by Rhesus Macaque MHC Class I: Crystal Structures of Mamu-A*01 Complexed with Two Immunogenic SIV Epitopes and Insights into CTL Escape
Authors: Chu Fuliang , Lou Zhiyong , Chen Yu Wai , Liu Yiwei , Gao Bin , Zong Lili , Khan Abdul Hamid , Bell John I. , Rao Zihe , Gao George F. 
Published: April 2014

AbstractThe infection of rhesus macaques (Macaca mulatta) by the SIV is the best animal model for studying HIV infection and for AIDS vaccine development. A prevalent MHC class I allele, Mamu-A*01, is known to correlate with containment of SIV, which has been extensively explored in studies of CTL-based vaccination concepts. We determined the crystal structures of Mamu-A*01 complexed with two immunodominant SIV epitopes: the nonamer CM9 of group-specific Ag (Gag, 181–189; CTPYDINQM) and the octamer TL8 of transcription activator (Tat, 28–35; TTPESANL). The overall structures of the two Mamu-A*01 complexes are similar to other MHC class I molecules. Both structures confirm the presence of an absolutely conserved proline anchor residue in the P3 position of the Ag, bound to a D pocket of the Mamu-A*01 H chain with optimal surface complementarity. Like other MHC/peptide complex structures, the P2 and C-terminal residues of the epitopes are also important for anchoring to the MHC molecule, whereas the middle residues form an arch and their side chains are directed into solvent. These two structures reveal details of how Mamu-A*01 interacts with two well-studied epitopes at the atomic level. We discuss the structural basis of CTL escape, based on molecular models made possible by these two structures. The results we present in this study are most relevant for the rational design of Mamu-A*01-restricted CTL epitopes with improved binding, as a step toward development of AIDS vaccines.
Promoter Region Architecture and Transcriptional Regulation of the Genes for the MHC Class I-Related Chain A and B Ligands of NKG2D
Authors: Venkataraman Gopalakrishnan M. , Suciu Dominic , Groh Veronika , Boss Jeremy M. , Spies Thomas 
Published: April 2014

Abstract
Ligands of the NKG2D receptor, which activates NK cells and costimulates effector T cells, are inducibly expressed under harmful conditions, such as malignancies and microbial infections. Moreover, aberrant expression in autoimmune disease lesions may contribute to disease progression. Among these ligands are the closely related human MHC class I-related chains (MIC) A and B, which appear to be regulated by cellular stress. Analyses of MIC gene 5′-end flanking regions in epithelial tumor cells defined minimal core promoters that directed near maximum heat shock- or oxidative stress-induced transcriptional activation. Considerably larger fully functional promoters were required for maximum proliferation-associated activation. These activities were dependent on core promoter sequences that included heat shock elements, which inducibly bound heat shock factor 1, TATA-like elements, and constitutively occupied Sp1 and inverted CCAAT box factor sites. By contrast, MIC gene activation by CMV infection was largely independent of these and upstream promoter sequences, and expression of viral immediate early gene (IE1 or IE2) products was sufficient for induction of transcription and surface protein expression. Altogether, these results reveal distinct modes of activation of the genes for the MIC ligands of NKG2D and provide a molecular framework for analyses of gene regulation under different cellular insult conditions.
Age-Associated Defect in Human TLR-1/2 Function
Authors: van Duin David , Mohanty Subhasis , Thomas Venetta , Ginter Sandra , Montgomery Ruth R. , Fikrig Erol , Allore Heather G. , Medzhitov Ruslan , Shaw Albert C. 
Published: April 2014

Abstract
The effects of aging on human TLR function remain incompletely understood. We assessed TLR function and expression in peripheral blood monocytes from 159 subjects in 2 age categories, 21–30 and &gt;65 years of age, using a multivariable mixed effect model. Using flow cytometry to assess TLR-induced cytokine production, we observed a substantial, highly significant defect in TLR1/2-induced TNF-α (p = 0.0003) and IL-6 (p &lt; 0.0001) production, in older adults compared with young controls. In contrast to findings in aged mice, other TLR (including TLR2/6)-induced cytokine production appeared largely intact. These differences were highly significant even after correcting for covariates including gender, race, medications, and comorbidities. This defect in TLR1/2 signaling may result from alterations in baseline TLR1 surface expression, which was decreased by 36% in older adults (p &lt; 0.0001), whereas TLR2 surface expression was unaffected by aging. Production of IL-6 (p &lt; 0.0001) and TNF-α (p = 0.003) after stimulation by N-palmitoyl-S-[2,3-bis(palmitoyloxy)-(2R,S)-propyl]-Cys-[S]-Ser1-[S]-Lys(4) trihydrochloride was strongly associated with TLR1 surface expression. Diminished TLR1/2 signaling may contribute to the increased infection-related morbidity and mortality and the impaired vaccine responses observed in aging humans.
TLR4, Ethanol, and Lipid Rafts: A New Mechanism of Ethanol Action with Implications for other Receptor-Mediated Effects
Authors: Szabo Gyongyi , Dolganiuc Angela , Dai Qun , Pruett Stephen B. 
Published: April 2014

Abstract
Ethanol (EtOH) is the most widely abused substance in the United States, and it contributes to well-documented harmful (at high dosages) and beneficial (at low dosages) changes in inflammatory and immune responses. Lipid rafts have been implicated in the regulation and activation of several important receptor complexes in the immune system, including the TLR4 complex. Many questions remain about the precise mechanisms by which rafts regulate the assembly of these receptor complexes. Results summarized in this review indicate that EtOH acts by altering the LPS-induced redistribution of components of the TLR4 complex within the lipid raft and that this is related to changes in actin cytoskeleton rearrangement, receptor clustering, and subsequent signaling. EtOH provides an example of an immunomodulatory drug that acts at least in part by modifying lipid rafts, and it could represent a model to probe the relationships between rafts, receptor complexes, and signaling.
Cutting Edge: A Regulatory T Cell-Dependent Novel Function of CD25 (IL-2Rα) Controlling Memory CD8+ T Cell Homeostasis
Authors: Sharma Rahul , Zheng Lingjie , Deshmukh Umesh S. , Jarjour Wael N. , Sung Sun-sang J. , Fu Shu Man , Ju Shyr-Te 
Published: April 2014

Abstract
A massive systemic expansion of CD8+ memory T (TM) cells and a remarkable increase in circulating IL-2 were observed only in IL-2Rα (CD25) knockout (KO) mice but not in IL-2 KO and scurfy mice, although all three mutants lack regulatory T (Treg) cells. However, both phenotypes were suppressed by the transfer of Treg cells. The data presented indicate that Treg cell deficiency drives naive T cells to TM cells. The lack of high-affinity IL-2R in IL-2Rα KO mice increases circulating IL-2 that is then preferentially used by CD8+ TM cells through its abundant low-affinity IL-2R, resulting in systemic CD8+ TM cell dominance. Our study demonstrates the critical control of CD8+ TM cell homeostasis by a Treg cell-dependent novel function of CD25 and resolves its mechanism of action.
Cutting Edge: Monarch-1 Suppresses Non-Canonical NF-κB Activation and p52-Dependent Chemokine Expression in Monocytes
Authors: Lich John D. , Williams Kristi L. , Moore Chris B. , Arthur Janelle C. , Davis Beckley K. , Taxman Debra J. , Ting Jenny P-Y. 
Published: April 2014

Abstract
CATERPILLER (NOD, NBD-LRR) proteins are rapidly emerging as important mediators of innate and adaptive immunity. Among these, Monarch-1 operates as a novel attenuating factor of inflammation by suppressing inflammatory responses in activated monocytes. However, the molecular mechanisms by which Monarch-1 performs this important function are not well understood. In this report, we show that Monarch-1 inhibits CD40-mediated activation of NF-κB via the non-canonical pathway in human monocytes. This inhibition stems from the ability of Monarch-1 to associate with and induce proteasome-mediated degradation of NF-κB inducing kinase. Congruently, silencing Monarch-1 with shRNA enhances the expression of p52-dependent chemokines.
Tolerization of Tumor-Specific T Cells Despite Efficient Initial Priming in a Primary Murine Model of Prostate Cancer
Authors: Anderson Michael J. , Shafer-Weaver Kimberly , Greenberg Norman M. , Hurwitz Arthur A. 
Published: April 2014

Abstract
In this report, we studied T cell responses to a prostate cancer Ag by adoptively transferring tumor Ag-specific T cells into prostate tumor-bearing mice. Our findings demonstrate that CD8+ T cells initially encountered tumor Ag in the lymph node and underwent an abortive proliferative response. Upon isolation from the tumor, the residual tumor-specific T cells were functionally tolerant of tumor Ag as measured by their inability to degranulate and secrete IFN-γ and granzyme B. We next sought to determine whether providing an ex vivo-matured, peptide-pulsed dendritic cell (DC) vaccine could overcome the tolerizing mechanisms of tumor-bearing transgenic adenocarcinoma of the mouse prostate model mice. We demonstrate that tumor Ag-specific T cells were protected from tolerance following provision of the DC vaccine. Concurrently, there was a reduction in prostate tumor size. However, even when activated DCs initially present tumor Ag, T cells persisting within the tolerogenic tumor environment gradually lost Ag reactivity. These results suggest that even though a productive antitumor response can be initiated by a DC vaccine, the tolerizing environment created by the tumor still exerts suppressive effects on the T cells. Furthermore, our results demonstrate that when trying to elicit an effective antitumor immune response, two obstacles must be considered: to maintain tumor Ag responsiveness, T cells must be efficiently primed to overcome tumor Ag presented in a tolerizing manner and protected from the suppressive mechanisms of the tumor microenvironment.
An In Vivo Cytotoxicity Threshold for Influenza A Virus-Specific Effector and Memory CD8+ T Cells
Authors: Stambas John , Doherty Peter C. , Turner Stephen J. 
Published: April 2014

Abstract
Influenza A virus infection of C57BL/6 (B6) mice is characterized by prominent CD8+ T cell responses to H2Db complexed with peptides from the viral nucleoprotein (NP366, ASNENMETM) and acid polymerase (PA224, SSLENFRAYV). An in vivo cytotoxicity assay that depends on the adoptive transfer of peptide-pulsed, syngeneic targets was used in this study to quantitate the cytotoxic potential of DbNP366- and DbPA224-specific acute and memory CD8+ T cells following primary or secondary virus challenge. Both T cell populations displayed equivalent levels of in vivo effector function when comparable numbers were transferred into naive B6 hosts. Cytotoxic activity following primary infection clearly correlated with the frequency of tetramer-stained CD8+ T cells. This relationship looked, however, to be less direct following secondary exposure, partly because the numbers of CD8+DbNP366+ T cells were greatly in excess. However, calculating the in vivo E:T ratios indicated that in vivo lysis, like many other biological functions, is threshold dependent. Furthermore, the capacity to eliminate peptide-pulsed targets was independent of the differentiation state (i.e., primary or secondary effectors) and was comparable for the two T cell specificities that were analyzed. These experiments provide insights that may be of value for adoptive immunotherapy, where careful consideration of both the activation state and the number of effector cells is required.
An Alternative Pathway of NF-κB Activation Results in Maturation and T Cell Priming Activity of Dendritic Cells Overexpressing a Mutated IκBα
Authors: Moore Fabrice , Buonocore Sofia , Aksoy Ezra , Ouled-Haddou Najate , Goriely Stanislas , Lazarova Elena , Paulart Frédéric , Heirman Carlo , Vaeremans Elsy , Thielemans Kris , Goldman Michel , Flamand Véronique 
Published: April 2014

Abstract
Maturation of dendritic cells (DC) is a critical step in the induction of T cell responses and depends on the activation of NF-κB transcription factors. Therefore, inhibition of NF-κB activation has been proposed as a strategy to maintain DC in an immature stage and to promote immune tolerance. Herein, we generated murine myeloid DC expressing a mutated IκBα acting as a superrepressor of the classical NF-κB pathway (s-rIκB DC) to investigate the consequences of NF-κB inhibition on the ability of DC to prime T cell responses. Upon in vitro LPS activation, maturation of s-rIκB DC was profoundly impaired as indicated by defective up-regulation of MHC class II and costimulatory molecules and reduced secretion of IL-12 p70 and TNF-α. In contrast, after injection, s-rIκB DC had the same capacity as control DC to migrate to draining lymph node and to induce Th1- and Th2-type cytokine production in a MHC class II-incompatible host mice. Likewise, s-rIκB DC pulsed with OVA were as efficient as control DC to induce Ag-specific T cell responses in vivo. Indeed, further in vitro experiments established that s-rIκB DC undergo efficient maturation upon prolonged contact with activated T cells via the alternative pathway of NF-κB activation triggered at least partly by lymphotoxin β receptor ligation and involving processing of p100/RelB complexes.
Environmental and Intrinsic Factors Lead to Antigen Unresponsiveness in CD4+ Recent Thymic Emigrants from Aged Mice
Authors: Clise-Dwyer Karen , Huston Gail E. , Buck Amanda L. , Duso Debra K. , Swain Susan L. 
Published: April 2014

Abstract
Naive CD4 cells from aged mice respond inefficiently to Ag, but the factors that underlie the age-associated defects remain unclear. We have used two approaches to isolate recent thymic emigrants (RTE) in young and aged mice and have compared their capacity to respond to antigenic stimulation ex vivo. An in situ intrathymic CFSE injection labeled developing thymocytes and allowed the identification of RTE in secondary lymphoid tissues. Analysis of CFSE-labeled RTE and control unlabeled naive CD4 cells indicated that cells from aged mice were defective in their ability to increase intracellular Ca2+ concentration following TCR cross-linking. Aged naive and RTE CD4 also secreted less IL-2 and proliferated less than that of comparable young CD4 populations. Defects in effector generation in aged RTE were overcome by the addition of IL-2 to cultures. RTE from both polyclonal and TCR transgenic mice were compromised, indicating that defects were independent of TCR specificity. In the second model, the cotransfer of congenic marker-labeled young and aged BM cells into young and aged syngeneic hosts revealed that hyporesponsiveness in aged RTE was caused by a combination of defects intrinsic to CD4 progenitors and defects induced by the aged environment. Depletion of peripheral CD4 cells in aged mice led to production of new RTE that were not defective. The results of this study suggest that defects induced by environmental and lineage intrinsic factors act together to reduce responses to Ag in aged naive CD4 cells and that these defects can be overcome in aged CD4 cells produced during recovery from lymphopenia.
T-bet Regulates the Fate of Th1 and Th17 Lymphocytes in Autoimmunity
Authors: Gocke Anne R. , Cravens Petra D. , Ben Li-Hong , Hussain Rehana Z. , Northrop Sara C. , Racke Michael K. , Lovett-Racke Amy E. 
Published: April 2014

Abstract
IL-17-producing T cells (Th17) have recently been implicated in the pathogenesis of experimental autoimmune encephalomyelitis (EAE), an animal model for the human disease multiple sclerosis. However, little is known about the transcription factors that regulate these cells. Although it is clear that the transcription factor T-bet plays an essential role in the differentiation of IFN-γ-producing CD4+ Th1 lymphocytes, the potential role of T-bet in the differentiation of Th17 cells is not completely understood. In this study, therapeutic administration of a small interfering RNA specific for T-bet significantly improved the clinical course of established EAE. The improved clinical course was associated with suppression of newly differentiated T cells that express IL-17 in the CNS as well as suppression of myelin basic protein-specific Th1 autoreactive T cells. Moreover, T-bet was found to directly regulate transcription of the IL-23R, and, in doing so, influenced the fate of Th17 cells, which depend on optimal IL-23 production for survival. We now show for the first time that suppression of T-bet ameliorates EAE by limiting the differentiation of autoreactive Th1 cells, as well as inhibiting pathogenic Th17 cells via regulation of IL-23R.
The p85α Regulatory Subunit of Class IA Phosphoinositide 3-Kinase Regulates β-Selection in Thymocyte Development
Authors: Shiroki Fumiko , Matsuda Satoshi , Doi Tomomitsu , Fujiwara Mari , Mochizuki Yoshito , Kadowaki Takashi , Suzuki Harumi , Koyasu Shigeo 
Published: April 2014

Abstract
We examined the role of class IA PI3K in pre-TCR controlled β-selection and TCR-controlled positive/negative selection in thymic development. Using mice deficient for p85α, a major regulatory subunit of the class IA PI3K family, the role of class IA PI3K in β-selection was examined by injection of anti-CD3ε mAb into p85α−/−Rag-2−/− mice, which mimics pre-TCR signals. Transition of CD4−CD8− double-negative (DN) to CD4+CD8+ double-positive (DP) thymocytes triggered by anti-CD3ε mAb was significantly impaired in p85α−/−Rag-2−/− compared with p85α+/−Rag-2−/− mice. Furthermore, DP cell numbers were lower in p85α−/−DO11.10/Rag-2−/− TCR-transgenic mice than in DO11.10/Rag-2−/− mice. In addition, inhibition by IC87114 of the major class IA PI3K catalytic subunit expressed in lymphocytes, p110δ, blocked transition of DN to DP cells in embryonic day 14.5 fetal thymic organ culture without affecting cell viability. In the absence of phosphatase and tensin homolog deleted on chromosome 10, where class IA PI3K signals would be amplified, the DN to DP transition was accelerated. In contrast, neither positive nor negative selection in Rag-2−/−TCR-transgenic mice was perturbed by the lack of p85α. These findings establish an important function of class IA PI3K in the pre-TCR-controlled developmental transition of DN to DP thymocytes.
Kinetics and Organ Distribution of IL-17-Producing CD4 Cells in Proteolipid Protein 139–151 Peptide-Induced Experimental Autoimmune Encephalomyelitis of SJL Mice
Authors: Hofstetter Harald H. , Toyka Klaus V. , Tary-Lehmann Magdalena , Lehmann Paul V. 
Published: April 2014

Abstract
In experimental autoimmune encephalomyelitis (EAE), the production of proinflammatory cytokines by neuroantigen-specific T cells is thought to initiate and maintain the inflammatory autoimmune pathology. Because gene knockout strategies have shown that IFN-γ and TNF are not essential for EAE development, there is increasing interest in establishing the role of other proinflammatory cytokines, primarily IL-17 in EAE. We used an IL-17 ELISPOT assay to track the neuroantigen-specific IL-17-producing T cells at single-cell resolution in various organs of SJL mice undergoing PLP 139–151-induced EAE. Overall, the migration patterns and population kinetics of the PLP 139–151-specific IL-17-producing CD4 cells were reminiscent of the IFN-γ-producing cells, with the exception of IL-17 producers far outnumbering the IFN-γ and IL-2 producers in the inflamed CNS. The selective enrichment of IL-17-producing CD4 cells in the CNS is suggestive of the pathogenic role of an independent (non-Th1) IL-17-producing proinflammatory effector T cell class in EAE.
Streptococcus agalactiae GAPDH Is a Virulence-Associated Immunomodulatory Protein
Authors: Madureira Pedro , Baptista Marina , Vieira Marta , Magalhães Vanessa , Camelo Ana , Oliveira Liliana , Ribeiro Adília , Tavares Delfina , Trieu-Cuot Patrick , Vilanova Manuel , Ferreira Paula 
Published: April 2014

Abstract
Certain extracellular proteins produced by several pathogenic microorganisms interfere with the host immune system facilitating microbial colonization and were thus designated virulence-associated immunomodulatory proteins. In this study, a protein with B lymphocyte stimulatory activity was isolated from culture supernatants of Streptococcus agalactiae strain NEM316. This protein, with an apparent molecular mass of 45 kDa, was identified as GAPDH by N-terminal amino acid sequencing. The gapC gene was cloned and expressed in Escherichia coli for the production of a recombinant histidyl-tagged protein. The recombinant GAPDH (rGAPDH), purified in an enzymatically active form, induced in vitro an up-regulation of CD69 expression on B cells from normal and BCR transgenic mice. In addition, rGAPDH induced an increase in the numbers of total, but not of rGAPDH-specific, splenic Ig-secreting cells in C57BL/6 mice treated i.p. with this protein. These in vitro- and in vivo-elicited B cell responses suggest that the B cell stimulatory effect of rGAPDH is independent of BCR specificity. A S. agalactiae strain overexpressing GAPDH showed increased virulence as compared with the wild-type strain in C57BL/6 mice. This virulence was markedly reduced in IL-10-deficient and anti-rGAPDH antiserum-treated mice. These results suggest that IL-10 production, which was detected at higher concentrations in the serum of rGAPDH-treated mice, is important in determining the successfulness of the host colonization by S. agalactiae and they highlight the direct role of GAPDH in this process. Taken together, our data demonstrate that S. agalactiae GAPDH is a virulence-associated immunomodulatory protein.