bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Double-Edged Sword of Activation-Induced Cytidine Deaminase
Authors: Wu Xiaosheng , Geraldes Pedro , Platt Jeffrey L. , Cascalho Marilia 
Published: April 2014

Abstract
Activation-induced cytidine deaminase (AID) is required for Ig class switch recombination, a process that introduces DNA double-strand breaks in B cells. We show in this study that AID associates with the DNA-dependent protein kinase catalytic subunit (DNA-PKcs) promoting cell survival, presumably by resolving DNA double-strand breaks. Wild-type cells expressing AID mutants that fail to associate with DNA-PKcs or cells deficient in DNA-PKcs or 53BP1 expressing wild-type AID accumulate γH2AX foci, indicative of heightened DNA damage response. Thus, AID has two independent functions. AID catalyzes cytidine deamination that originates DNA double-strand breaks needed for recombination, and it promotes DNA damage response and cell survival. Our results thus resolve the paradox of how B cells undergoing DNA cytidine deamination and recombination exhibit heightened survival and suggest a mechanism for hyperIgM type II syndrome associated with AID mutants deficient in DNA-PKcs binding.
A Charged Amino Acid Residue in the Transmembrane/Cytoplasmic Region of Tapasin Influences MHC Class I Assembly and Maturation
Authors: Petersen Jason L. , Hickman-Miller Heather D. , McIlhaney Mary M. , Vargas Shanna E. , Purcell Anthony W. , Hildebrand William H. , Solheim Joyce C. 
Published: April 2014

Abstract
Tapasin influences the quantity and quality of MHC/peptide complexes at the cell surface; however, little is understood about the structural features that underlie its effects. Because tapasin, MHC class I, and TAP are transmembrane proteins, the tapasin transmembrane/cytoplasmic region has the potential to affect interactions at the endoplasmic reticulum membrane. In this study, we have assessed the influence of a conserved lysine at position 408, which lies in the tapasin transmembrane/cytoplasmic domain. We found that substitutions at position K408 in tapasin affected the expression of MHC class I molecules at the cell surface, and down-regulated tapasin stabilization of TAP. In addition to affecting TAP interaction with tapasin, the substitution of alanine, but not tryptophan, for the lysine at tapasin position 408 increased the amount of tapasin found in association with the open, peptide-free form of the HLA-B8 H chain. Tapasin K408A was also associated with more folded, β2-microglobulin-assembled HLA-B8 molecules than wild-type tapasin. Consistent with our observation of a large pool of tapasin K408A-associated HLA-B8 molecules, the rate at which HLA-B8 migrated from the endoplasmic reticulum was slower in tapasin K408A-expressing cells than in wild-type tapasin-expressing cells. Thus, the alanine substitution at position 408 in tapasin may interfere with the stable acquisition by MHC class I molecules of peptides that are sufficiently optimal to allow MHC class I release from tapasin.
Characterization of a B220+ Lymphoid Cell Subpopulation with Immune Modulatory Functions in Nasal-Associated Lymphoid Tissues
Authors: Rharbaoui Faiza , Bruder Dunja , Vidakovic Melita , Ebensen Thomas , Buer Jan , Guzmán Carlos A. 
Published: April 2014

AbstractComplex mechanisms operate on mucosal tissues to regulate immune responsiveness and tolerance. When the lymphocyte subpopulations from murine nasal-associated lymphoid tissues (NALT) were characterized, we observed an accumulation of B220lowCD3lowCD4−CD8−CD19−c-Kit+ cells. TCR transgenic mice and athymic mice were used for monitoring T cell lineage and the presence of extrathymic T cell precursors. The majority of cells from NALT exhibited a T cell precursor phenotype (CD4−CD8−CD19−c-Kit+). Fas-independent apoptosis was their main mechanism of cell death. We also demonstrated that B220lowCD4−CD8−CD19− cells from NALT exhibited the potential to down-regulate the activation of mature T cells. However, the innate immunity receptor TLR2 was also highly expressed by this cell subpopulation. Moreover, nasal stimulation with a TLR2/6 agonist resulted in a partial activation of the double-negative cells. These results suggest that the immune responses in NALT may be in part modulated by a cell subpopulation that maintains a tolerogenic milieu by its proapoptotic status and suppressive activity, which can be reverted through stimulation of a TLR signaling cascade.
Immune Selection of Hot-Spot β2-Microglobulin Gene Mutations, HLA-A2 Allospecificity Loss, and Antigen-Processing Machinery Component Down-Regulation in Melanoma Cells Derived from Recurrent Metastases following Immunotherapy
Authors: Chang Chien-Chung , Campoli Michael , Restifo Nicholas P. , Wang Xinhui , Ferrone Soldano 
Published: April 2014

Abstract
Scanty information is available about the mechanisms underlying HLA class I Ag abnormalities in malignant cells exposed to strong T cell-mediated selective pressure. In this study, we have characterized the molecular defects underlying HLA class I Ag loss in five melanoma cell lines derived from recurrent metastases following initial clinical responses to T cell-based immunotherapy. Point mutations in the translation initiation codon (ATG→ATA) and in codon 31 (TCA→TGA) of the β2-microglobulin (β2m) gene were identified in the melanoma cell lines 1074MEL and 1174MEL, respectively. A hot-spot CT dinucleotide deletion within codon 13–15 was found in the melanoma cell lines 1106MEL, 1180MEL, and 1259MEL. Reconstitution of β2m expression restored HLA class I Ag expression in the five melanoma cell lines; however, the HLA-A and HLA-B,-C gene products were differentially expressed by 1074MEL, 1106MEL, and 1259MEL cells. In addition, in 1259MEL cells, the Ag-processing machinery components calnexin, calreticulin, and low m.w. polypeptide 10 are down-regulated, and HLA-A2 Ags are selectively lost because of a single cytosine deletion in the HLA-A2 gene exon 4. Our results in conjunction with those in the literature suggest the emergence of a preferential β2m gene mutation in melanoma cells following strong T cell-mediated immune selection. Furthermore, the presence of multiple HLA class I Ag defects within a tumor cell population may reflect the accumulation of multiple escape mechanisms developed by melanoma cells to avoid distinct sequential T cell-mediated selective events.
Signaling through CD14 Attenuates the Inflammatory Response toBorrelia burgdorferi, the Agent of Lyme Disease
Authors: Benhnia Mohammed Rafii-El-Idrissi , Wroblewski Danielle , Akhtar Muhammad Naveed , Patel Raina A. , Lavezzi Wendy , Gangloff Sophie C. , Goyert Sanna M. , Caimano Melissa J. , Radolf Justin D. , Sellati Timothy J. 
Published: April 2014

AbstractLyme disease is a chronic inflammatory disorder caused by the spirochetal bacterium, Borrelia burgdorferi. In vitro evidence suggests that binding of spirochetal lipoproteins to CD14, a pattern recognition receptor expressed on monocytes/macrophages and polymorphonuclear cells, is a critical requirement for cellular activation and the subsequent release of proinflammatory cytokines that most likely contribute to symptomatology and clinical manifestations. To test the validity of this notion, we assessed the impact of CD14 deficiency on Lyme disease in C3H/HeN mice. Contrary to an anticipated diminution in pathology, CD14−/− mice exhibited more severe and persistent inflammation than did CD14+/+ mice. This disparity reflects altered gene regulation within immune cells that may engender the higher bacterial burden and serum cytokine levels observed in CD14−/− mice. Comparing their in vitro stimulatory activity, live spirochetes, but not lysed organisms, were a potent CD14-independent stimulus of cytokine production, triggering an exaggerated response by CD14−/− macrophages. Collectively, our in vivo and in vitro findings support the provocative notion that: 1) pattern recognition by CD14 is entirely dispensable for elaboration of an inflammatory response to B. burgdorferi, and 2) CD14-independent signaling pathways are inherently more destructive than CD14-dependent pathways. Continued study of CD14-independent signaling pathways may provide mechanistic insight into the inflammatory processes that underlie development of chronic inflammation.
Leukotriene B4 Protects Latently Infected Mice against Murine Cytomegalovirus Reactivation following Allogeneic Transplantation
Authors: Gosselin Jean , Borgeat Pierre , Flamand Louis 
Published: April 2014

Abstract
Human CMV is often associated with transplant rejection and opportunistic infections such as pneumonia in immunosuppressed patients. Current anti-CMV therapies, although effective, show relatively high toxicity, which seriously limits their long-term use. In this study, we provide evidence that leukotriene B4 (LTB4) plays an important role in the fight against murine CMV (MCMV) infection in vivo. Intravenous administration of 50 and 500 ng/kg/day of LTB4 to mice infected with a lethal dose of MCMV significantly increases their survival (50 and 70%, respectively), compared with the placebo-treated group (10% of survival). In mice infected with a sublethal dose of MCMV and treated daily with 50 ng/kg/day of LTB4, the salivary gland viral loads were found to be reduced by 66% compared with the control group. Furthermore, using an allogeneic bone marrow transplantation mouse model, the frequency of MCMV reactivation from latently infected mice was much lower (38%) in LTB4 (500 ng/kg)-treated mice than in the placebo-treated group (78%). Finally, in experiments using 5-lipoxygenase-deficient mice, MCMV viral loads in salivary glands were found to be higher in animals unable to produce leukotrienes than in the control groups, supporting a role of endogenous 5-lipoxygenase products, possibly LTB4, in host defense against CMV infection.
Expression and Activity of β-Defensins and LL-37 in the Developing Human Lung
Authors: Starner Timothy D. , Agerberth Birgitta , Gudmundsson Gudmundur H. , McCray Paul B. 
Published: April 2014

Abstract
Immaturity of innate immunity contributes to the increased susceptibility of human neonates to infection. The lung is a major portal of entry for potential pathogens in the neonate, and human β-defensins (HBDs) and LL-37 participate in pulmonary innate immunity. We hypothesized that these antimicrobial factors would be developmentally regulated, expressed by neonatal pulmonary tissues, and participate in neonatal innate immunity. We found HBD-2 to be the predominant β-defensin in human neonatal lung. HBD-2 mRNA expression was developmentally regulated, induced by the proinflammatory factor IL-1β, and decreased by dexamethasone. Additionally, HBD-2 abundance in neonatal tracheal aspirates increased as a function of gestational age. HBD-1 had a lower level of expression compared with HBD-2 and was induced by dexamethasone. HBD-3 and LL-37 messages were not detected in airway epithelial cultures. Additionally, each antimicrobial peptide exhibited a unique spectrum of antimicrobial activity and salt sensitivity against bacteria commonly causing sepsis in the neonate. Lower levels of HBD-2 may be one factor contributing to the increased susceptibility of premature infants to pulmonary infections.
TLR-Induced Inflammation in Cystic Fibrosis and Non-Cystic Fibrosis Airway Epithelial Cells
Authors: Greene Catherine M. , Carroll Tomás P. , Smith Stephen G. J. , Taggart Clifford C. , Devaney James , Griffin Siobhan , O’Neill Shane J. , McElvaney Noel G. 
Published: April 2014

Abstract
Cystic fibrosis (CF) is a genetic disease characterized by severe neutrophil-dominated airway inflammation. An important cause of inflammation in CF is Pseudomonas aeruginosa infection. We have evaluated the importance of a number of P. aeruginosa components, namely lipopeptides, LPS, and unmethylated CpG DNA, as proinflammatory stimuli in CF by characterizing the expression and functional activity of their cognate receptors, TLR2/6 or TLR2/1, TLR4, and TLR9, respectively, in a human tracheal epithelial line, CFTE29o−, which is homozygous for the ΔF508 CF transmembrane conductance regulator mutation. We also characterized TLR expression and function in a non-CF airway epithelial cell line 16HBE14o−. Using RT-PCR, we demonstrated TLR mRNA expression. TLR cell surface expression was assessed by fluorescence microscopy. Lipopeptides, LPS, and unmethylated CpG DNA induced IL-8 and IL-6 protein production in a time- and dose-dependent manner. The CF and non-CF cell lines were largely similar in their TLR expression and relative TLR responses. ICAM-1 expression was also up-regulated in CFTE29o− cells following stimulation with each agonist. CF bronchoalveolar lavage fluid, which contains LPS, bacterial DNA, and neutrophil elastase (a neutrophil-derived protease that can activate TLR4), up-regulated an NF-κB-linked reporter gene and increased IL-8 protein production in CFTE29o− cells. This effect was abrogated by expression of dominant-negative versions of MyD88 or Mal, key signal transducers for TLRs, thereby implicating them as potential anti-inflammatory agents for CF.
Cutaneous Antigen Priming via Gene Gun Leads to Skin-Selective Th2 Immune-Inflammatory Responses
Authors: Alvarez David , Harder Greg , Fattouh Ramzi , Sun Jiangfeng , Goncharova Susanna , Stämpfli Martin R. , Coyle Anthony J. , Bramson Jonathan L. , Jordana Manel 
Published: April 2014

AbstractIt is becoming increasingly evident that the compartmentalization of immune responses is governed, in part, by tissue-selective homing instructions imprinted during T cell differentiation. In the context of allergic diseases, the fact that “disease” primarily manifests in particular tissue sites, despite pervasive allergen exposure, supports this notion. However, whether the original site of Ag exposure distinctly privileges memory Th2 immune-inflammatory responses to the same site, while sparing remote tissue compartments, remains to be fully investigated. We examined whether skin-targeted delivery of plasmid DNA encoding OVA via gene-gun technology in mice could generate allergic sensitization and give rise to Th2 effector responses in the skin as well as in the lung upon subsequent Ag encounter. Our data show that cutaneous Ag priming induced OVA-specific serum IgE and IgG1, robust Th2-cytokine production, and late-phase cutaneous responses and systemic anaphylactic shock upon skin and systemic Ag recall, respectively. However, repeated respiratory exposure to aerosolized OVA failed to instigate airway inflammatory responses in cutaneous Ag-primed mice, but not in mice initially sensitized to OVA via the respiratory mucosa. Importantly, these contrasting airway memory responses correlated with the occurrence of Th2 differentiation events at anatomically separate sites: indeed cutaneous Ag priming resulted in Ag-specific proliferative responses and Th2 differentiation in skin-, but not thoracic-, draining lymph nodes. These data indicate that Ag exposure to the skin leads to Th2 differentiation within skin-draining lymph nodes and subsequent Th2 immunity that is selectively manifested in the skin.
Naturally Acquired MAGE-A10- and SSX-2-Specific CD8+ T Cell Responses in Patients with Hepatocellular Carcinoma
Authors: Bricard Gabriel , Bouzourene Hanifa , Martinet Olivier , Rimoldi Donata , Halkic Nermin , Gillet Michel , Chaubert Pascal , MacDonald H. Robson , Romero Pedro , Cerottini Jean-Charles , Speiser Daniel E. 
Published: April 2014

Abstract
Immunotherapy is being proposed to treat patients with hepatocellular carcinoma (HCC). However, more detailed knowledge on tumor Ag expression and specific immune cells is required for the preparation of highly targeted vaccines. HCC express a variety of tumor-specific Ags, raising the question whether CTL specific for such Ags exist in HCC patients. Indeed, a recent study revealed CTLs specific for two cancer-testis (CT) Ags (MAGE-A1 and MAGE-A3) in tumor infiltrating lymphocytes of HCC patients. Here we assessed the presence of T cells specific for additional CT Ags: MAGE-A10, SSX-2, NY-ESO-1, and LAGE-1, which are naturally immunogenic as demonstrated in HLA-A2+ melanoma patients. In two of six HLA-A2+ HCC patients, we found that MAGE-A10- and/or SSX-2-specific CD8+ T cells naturally responded to the disease, because they were enriched in tumor lesions but not in nontumoral liver. Isolated T cells specifically and strongly killed tumor cells in vitro, providing evidence that these CTL were selected in vivo for high avidity Ag recognition. Therefore, besides melanoma, HCC is the second solid human tumor with clear evidence for in vivo tumor recognition by T cells, providing the rational for specific immunotherapy, based on immunization with CT Ags such as MAGE-A10 and SSX-2.
Modulation of TNF-α Gene Expression by IFN-γ and Pamidronate in Murine Macrophages: Regulation by STAT1-Dependent Pathways
Authors: Takagi Kae , Takagi Masatoshi , Kanangat Siva , Warrington Kenneth J. , Shigemitsu Hidenobu , Postlethwaite Arnold E. 
Published: April 2014

Abstract
Aminobisphosphonates are drugs used in the treatment of hypercalcemia, Paget’s disease, osteoporosis, and malignancy. Some patients treated with aminobisphosphonates have a transient febrile reaction that may be caused by an increased serum concentration of proinflammatory cytokines. Aminobisphosphonates induce the production of certain proinflammatory cytokines in vitro, especially in cells of monocytic lineage. A unique feature of aminobisphosphonates is that they bind the Vγ2Vδ2 class of T cells, which are found only in primates, and stimulate cytokine production. The effects of aminobisphosphonates on other cells, including macrophages, are incompletely understood. We show in this study that treatment of murine macrophages with pamidronate, a second generation aminobisphosphonate, induces TNF-α production. Furthermore, pretreatment of murine macrophages with pamidronate before stimulation with IFN-γ significantly augments IFN-γ-dependent production of TNF-α. This pamidronate-mediated augmentation of TNF-α production results in sustained phosphorylation of the tyrosine residue at position 701 of STAT1 after IFN-γ treatment. Our data suggest that this sustained phosphorylation results from inhibition of protein tyrosine phosphatase activity. We also show that pamidronate treatment increases TNF-α production in vivo in mice. Pamidronate-augmented TNF-α production by macrophages might be a useful strategy for cytokine-based anticancer therapy.
P2X7 Receptor-Dependent and -Independent T Cell Death Is Induced by Nicotinamide Adenine Dinucleotide
Authors: Kawamura Hiroki , Aswad Fred , Minagawa Masahiro , Malone Karen , Kaslow Harvey , Koch-Nolte Friederich , Schott William H. , Leiter Edward H. , Dennert Gunther 
Published: April 2014

AbstractAdding NAD to murine T lymphocytes inhibits their functions and induces annexin V binding. This report shows that NAD induces cell death in a subset of T cells within seconds whereas others do not die until many hours later. Low NAD concentrations (&lt;10 μM) suffice to trigger rapid cell death, which is associated with annexin V binding and membrane pore formation, is not blocked by the caspase inhibitor Z-VADfmk, and requires functional P2X7 receptors. The slower induction of death requires higher NAD concentrations (&gt;100 μM), is blocked by caspase inhibitor Z-VADfmk, is associated with DNA fragmentation, and does not require P2X7 receptors. T cells degrade NAD to ADP-ribose (ADPR), and adding ADPR to T cells leads to slow but not rapid cell death. NAD but not ADPR provides the substrate for ADP-ribosyltransferase (ART-2)-mediated attachment of ADP-ribosyl groups to cell surface proteins; expression of ART-2 is required for NAD to trigger rapid but not slow cell death. These results support the hypothesis that cell surface ART-2 uses NAD but not ADPR to attach ADP-ribosyl groups to the cell surface, and that these groups act as ligands for P2X7 receptors that then induce rapid cell death. Adding either NAD or ADPR also triggers a different set of mechanisms, not requiring ART-2 or P2X7 receptors that more slowly induce cell death.
Regulation of IL-10 Gene Expression in Th2 Cells by Jun Proteins
Authors: Wang Zheng-Yu , Sato Hiroshi , Kusam Saritha , Sehra Sarita , Toney Lisa M. , Dent Alexander L. 
Published: April 2014

AbstractIL-10 is a key regulatory cytokine produced by T lymphocytes. Although Th2 cells are a major source of IL-10, little is known about IL-10 gene regulation in Th2 cells. High levels of IL-10 mRNA transcription are induced in the Th2 clone D10 after PMA plus ionomycin (P/I) stimulation; however we found that the IL-10 promoter was not inducible by P/I in D10 cells. We therefore sought regulatory regions in the IL-10 gene that could promote P/I-activated transcription in Th2 cells. Two strong DNase I-hypersensitive sites (DHSSs) were identified in the IL-10 gene in mouse T cells, and conserved noncoding sequences (CNSs) between the mouse and human IL-10 genes were also identified. One IL-10 DHSS maps within or next to a highly conserved CNS region, CNS-3. The CNS-3 region contains an AP-1 site that binds JunB and c-Jun proteins specifically in Th2 cells and not in Th1 cells. The CNS-3 element activates transcription from the IL-10 promoter after P/I stimulation and is responsive to c-Jun and JunB. Retroviral mediated-expression of either c-Jun or JunB in primary T cells led to a large increase in IL-10 expression, and inhibition of AP-1 activity by a dominant negative form of c-Jun in primary T cells strongly repressed IL-10 expression. IFN-γ was relatively unaffected by modulations in AP-1 activity. These data indicate that we have identified a novel regulatory element that can specifically activate transcription of the IL-10 gene in Th2 cells via the AP-1/Jun pathway.
Variable-Region-Identical Antibodies Differing in Isotype Demonstrate Differences in Fine Specificity and Idiotype
Authors: Torres Marcela , May Rena , Scharff Matthew D. , Casadevall Arturo 
Published: April 2014

Abstract
A central tenet of the current understanding of the relationship between Ab structure and function is that the variable region domain is solely responsible for Ag specificity. However, this view was recently challenged by the observation that families of mouse-human chimeric Abs with identical V regions demonstrate differences in fine specificity and by reports of changes in Ab Id structure with isotype switching. Here we revisited this question by evaluating the reactivity of two families of murine IgG switch variants that differed in V region usage for Cryptococcus neoformans glucuronoxylomannan, glucuronoxylomannan peptide mimetics, and anti-Id mAbs. The results reveal isotype-related differences in fine specificities and Id for two mAb isotype switched families, thus establishing the validity of this observation with sets of homologous Abs. The results suggest that the C region affects V region protein conformation, leading to differences in fine specificity and Id. The finding that isotype can affect fine specificity has major implications for current concepts of the generation of secondary responses, idiotypic network regulation, and isotype function. Given that isotype class switching and Ig gene somatic hypermutation share molecular mechanisms, these observations unify these processes in the sense that both can alter specificity and affinity.