bluuebunny/crossref_metadata_2025_split huggingface dataset:
Genetic Dissection of Lupus Pathogenesis: Sle3/5 Impacts IgH CDR3 Sequences, Somatic Mutations, and Receptor Editing
Authors: Wakui Masatoshi , Kim Jinho , Butfiloski Edward J. , Morel Laurence , Sobel Eric S. 
Published: April 2014

Abstract
Sle3/5 is a lupus susceptibility locus identified on mouse chromosome 7 of the New Zealand Black/New Zealand White (NZB/NZW)-derived NZM2410 strain. Based on previous observations, this locus appears to contribute to lupus pathogenesis through its impact on diversification of immune responses. To understand how Sle3/5 affects somatic diversification of humoral responses, we analyzed IgH rearrangements preferentially encoding hapten-reactive IgG1 repertoires after immunization and assessed peripheral IgH VDJ recombination activities in C57BL/6 (B6) mice congenic for Sle3/5 (B6.Sle3/5). In addition to altered somatic VH mutation profiles, sequences from B6.Sle3/5 mice exhibited atypical IgH CDR3 structures characteristic of autoreactive B cells and consistent with peripheral B cells bearing putatively edited receptors. Significant expression of Rag genes and circular VHD gene excision products were detected in splenic mature B cells of B6.Sle3/5 but not B6 mice, showing that peripheral IgH rearrangements occurred beyond allelic exclusion. Taken together, on the nonautoimmune background, Sle3/5 affected VHDJH junctional diversity and VH mutational diversity and led to recombinational activation of allelically excluded IgH genes in the periphery. Such impact on somatic IgH diversification may contribute to the development of autoreactive B cell repertoires. This is the first report to present evidence for significant association of a lupus susceptibility locus, which has been mapped to a chromosomal region in which no Ig genes have been identified, with somatic IgH sequence diversity and peripheral H chain receptor editing or revision without relying upon Ig transgene strategies.
A Distinct Region of the Murine IFN-γ Promoter Is Hypomethylated from Early T Cell Development through Mature Naive and Th1 Cell Differentiation, but Is Hypermethylated in Th2 Cells
Authors: Winders Benjamin R. , Schwartz Ronald H. , Bruniquel Denis 
Published: April 2014

Abstract
Reports on the status of DNA methylation of the IFN-γ gene during T cell development in human and mouse have presented somewhat contradictory results. In this study we demonstrate in the mouse that methylation of the IFN-γ promoter inhibits its transcriptional activity, and define a small hypomethylated region in T cells that correlates with transcription. The IFN-γ promoter was also hypomethylated in NK cells, but not in B cells or nonhemopoietic tissues. Surprisingly, unlike the promoters of the IL-2 and IL-4 genes, the IFN-γ promoter was hypomethylated in naive CD4+ and CD8+ T cells, and in this form from very early in T cell development. A population of non-B, non-T, non-NK cells containing the hypomethylated promoter was also found in the bone marrow. The hypomethylated state appears stable until peripheral CD4+ T cells differentiate in response to Ag and APC. After T cell stimulation in vitro under Th2 conditions, but far less so under Th1 conditions, CD4+ cells display a more methylated IFN-γ promoter, which may contribute to the lack of expression of IFN-γ in these preactivated cells. Our experiments support a new model of IFN-γ chromatin structural changes in murine T cell development that differs from what has been previously published for human T cells.
Chicken Ig-Like Receptor B2, a Member of a Multigene Family, Is Mainly Expressed on B Lymphocytes, Recruits Both Src Homology 2 Domain Containing Protein Tyrosine Phosphatase (SHP)-1 and SHP-2, and Inhibits Proliferation
Authors: Viertlboeck Birgit C. , Crooijmans Richard P. M. A. , Groenen Martien A. M. , Göbel Thomas W. F. 
Published: April 2014

Abstract
Ig-like inhibitory receptors have been the focus of intensive research particularly in mouse and human. We report the cloning and characterization of three novel inhibitory chicken Ig-like receptors (CHIR) that display a two Ig-domain extracellular structure, a transmembrane region lacking charged residues and a cytoplasmic domain containing two ITIM. The localization of all receptors to a small genomic region and the hybridization pattern indicated that they belong to a multigene family. The genomic structure of the extracellular domain with two exons encoding the signal peptide and single exons for each Ig domain resembled that of all human leukocyte Ig-like receptors and killer cell Ig-like receptors, whereas the exons encoding the C terminus displayed a structure closely resembling killer cell Ig-like receptor genes. A mAb generated against one receptor designated CHIR-B2 reacted with all B cells and a small T cell subset, but not with monocytes, thrombocytes, or various leukocyte-derived cell lines. The mAb immunoprecipitated a 46-kDa protein from bursal cells and transfected cells. The Src homology 2 domain containing protein tyrosine phosphatase (SHP)-2 bound to CHIR-B2 even in unstimulated cells, whereas pervanadate treatment induced the tyrosine phosphorylation and recruitment of several CHIR-B2-associated proteins including SHP-1 and increased levels of SHP-2. Moreover, mAb cross-linking of CHIR-B2 reduced the proliferation of a stable transfected cell line. Together, we have identified a multigene family containing multiple CHIR including one receptor designated CHIR-B2 that is mainly expressed on B lymphocytes and inhibits cellular proliferation by recruitment of SHP-1 and SHP-2.
Key Molecular Contacts Promote Recognition of the BAFF Receptor by TNF Receptor-Associated Factor 3: Implications for Intracellular Signaling Regulation
Authors: Ni Chao-Zhou , Oganesyan Gagik , Welsh Kate , Zhu Xiuwen , Reed John C. , Satterthwait Arnold C. , Cheng Genhong , Ely Kathryn R. 
Published: April 2014

Abstract
B cell-activating factor belonging to the TNF family receptor (BAFF-R), a member of the TNFR superfamily, plays a role in autoimmunity after ligation with BAFF ligand (also called TALL-1, BLyS, THANK, or zTNF4). BAFF/BAFF-R interactions are critical for B cell regulation, and signaling from this ligand-receptor complex results in NF-κB activation. Most TNFRs transmit signals intracellularly by recruitment of adaptor proteins called TNFR-associated factors (TRAFs). However, BAFF-R binds only one TRAF adaptor, TRAF3, and this interaction negatively regulates activation of NF-κB. In this study, we report the crystal structure of a 24-residue fragment of the cytoplasmic portion of BAFF-R bound in complex with TRAF3. The recognition motif 162PVPAT166 in BAFF-R is accommodated in the same binding crevice on TRAF3 that binds two related TNFRs, CD40 and LTβR, but is presented in a completely different structural framework. This region of BAFF-R assumes an open conformation with two extended strands opposed at right angles that each make contacts with TRAF3. The recognition motif is located in the N-terminal arm and intermolecular contacts mediate TRAF recognition. In the C-terminal arm, key stabilizing contacts are made, including critical hydrogen bonds with Gln379 in TRAF3 that define the molecular basis for selective binding of BAFF-R solely to this member of the TRAF family. A dynamic conformational adjustment of Tyr377 in TRAF3 occurs forming a new intermolecular contact with BAFF-R that stabilizes the complex. The structure of the complex provides a molecular explanation for binding affinities and selective protein interactions in TNFR-TRAF interactions.
TLR2 Recognizes a Bacterial Lipopeptide through Direct Binding
Authors: Vasselon Thierry , Detmers Patricia A. , Charron Dominique , Haziot Alain 
Published: April 2014

AbstractThe TLRs play an important role in the initiation of cellular innate immune responses to a wide range of bacterial products, including LPS and lipoproteins. Although rapid progress has been made on signaling functions of activated TLRs, the molecular mechanisms that lead to TLR activation are still poorly understood. We report in this study that the extracellular domain of TLR2 interacts directly with synthetic bacterial lipopeptide (sBLP), a potent analog of bacterial lipoproteins. Using fluorescently labeled sBLP complexed to soluble recombinant CD14 (rsCD14), we observed specific binding of sBLP to the surface of cells expressing TLR2 transgenes and to a recombinant soluble form of the TLR2 ectodomain. TLR2-mediated binding of sBLP at the cell surface did not require prior induction of intracellular signals. In addition, using a chimeric TLR2/TLR4 construct, we showed that the leucine-rich region of TLR2 carries the specificity for binding of the agonist and for initiating signaling. Specific binding of fluorescent sBLP to purified sTLR2 required sCD14. However, sCD14 was not part of the complex formed by soluble TLR2 and sBLP. Together, these data provide evidence that TLR2 recognizes sBLP through direct binding.
TLRs Govern Neutrophil Activity in Aspergillosis
Authors: Bellocchio Silvia , Moretti Silvia , Perruccio Katia , Fallarino Francesca , Bozza Silvia , Montagnoli Claudia , Mosci Paolo , Lipford Grayson B. , Pitzurra Lucia , Romani Luigina 
Published: April 2014

Abstract
Polymorphonuclear neutrophils (PMNs) are essential in initiation and execution of the acute inflammatory response and subsequent resolution of fungal infection. PMNs, however, may act as double-edged swords, as the excessive release of oxidants and proteases may be responsible for injury to organs and fungal sepsis. To identify regulatory mechanisms that may balance PMN-dependent protection and immunopathology in fungal infections, the involvement of different TLR-activation pathways was evaluated on human PMNs exposed to the fungus Aspergillus fumigatus. Recognition of Aspergillus and activation of PMNs occurred through the involvement of distinct members of the TLR family, each likely activating specialized antifungal effector functions. By affecting the balance between fungicidal oxidative and nonoxidative mechanisms, pro- and anti-inflammatory cytokine production, and apoptosis vs necrosis, the different TLRs ultimately impacted on the quality of microbicidal activity and inflammatory pathology. Signaling through TLR2 promoted the fungicidal activity of PMNs through oxidative pathways involving extracellular release of gelatinases and proinflammatory cytokines while TLR4 favored the oxidative pathways through the participation of azurophil, myeloperoxidase-positive, granules and IL-10. This translated in vivo in the occurrence of different patterns of fungal clearance and inflammatory pathology. Both pathways were variably affected by signaling through TLR3, TLR5, TLR6, TLR7, TLR8, and TLR9. The ability of selected individual TLRs to restore antifungal functions in defective PMNs suggests that the coordinated outputs of activation of multiple TLRs may contribute to PMN function in aspergillosis.
IFN Regulatory Factor 3-Dependent Induction of Type I IFNs by Intracellular Bacteria Is Mediated by a TLR- and Nod2-Independent Mechanism
Authors: Stockinger Silvia , Reutterer Benjamin , Schaljo Barbara , Schellack Carola , Brunner Sylvia , Materna Tilo , Yamamoto Masahiro , Akira Shizuo , Taniguchi Tadatsugu , Murray Peter J. , Müller Mathias , Decker Thomas 
Published: April 2014

Abstract
Like viruses, intracellular bacteria stimulate their host cells to produce type I IFNs (IFN-α and IFN-β). In our study, we investigated the signals and molecules relevant for the synthesis of and response to IFN by mouse macrophages infected with Listeria monocytogenes. We report that IFN-β is the critical immediate-early IFN made during infection, because the synthesis of all other type I IFN, expression of a subset of infection-induced genes, and the biological response to type I IFN was lost upon IFN-β deficiency. The induction of IFN-β mRNA and the IFN-β-dependent sensitization of macrophages to bacteria-induced death, in turn, was absolutely dependent upon the presence of the transcription factor IFN regulatory factor 3 (IRF3). IFN-β synthesis and signal transduction occurred in macrophages deficient for TLR or their adaptors MyD88, TRIF, or TRAM. Expression of Nod2, a candidate receptor for intracellular bacteria, increased during infection, but the protein was not required for Listeria-induced signal transduction to the Ifn-β gene. Based on our data, we propose that IRF3 is a convergence point for signals derived from structurally unrelated intracellular pathogens, and that L. monocytogenes stimulates a novel TLR- and Nod2-independent pathway to target IRF3 and the type I IFN genes.
Human Monocytes Infected with Yersinia pestis Express Cell Surface TLR9 and Differentiate into Dendritic Cells
Authors: Saikh Kamal U. , Kissner Teri L. , Sultana Afroz , Ruthel Gordon , Ulrich Robert G. 
Published: April 2014

Abstract
TLR9 recognizes DNA sequences containing hypomethylated CpG motifs and is a component of the innate immune system highly conserved during eukaryotic evolution. Previous reports suggested that the expression of TLR9 is restricted to plasmacytoid dendritic cells and B lymphocytes. Our results indicate that low levels of TLR9 are present on the cell surface of freshly isolated human monocytes, and expression is greatly increased by infection with Yersinia pestis. Enhanced cell surface TLR9 coincided with elevated levels of cytoplasmic TLR9 and recruitment of MyD88. Infected monocytes differentiated into mature dendritic cells, expressed IFN-α, and stimulated proliferative and cytotoxic T cell responses specific to Y. pestis. Furthermore, uninfected B cells and monocytes both increased cell surface TLR9, CD86, and HLA-DR in response to treatment with CpG-containing oligonucleotides, whereas cell surface TLR9 was down-modulated on infected dendritic cells by the addition of agonist oligonucleotide. Our results suggest that increased expression of TLR9 on the surface of infected cells may serve a role as an activation signal to other cells of the immune system.
Innate Imprinting by the Modified Heat-Labile Toxin of Escherichia coli (LTK63) Provides Generic Protection against Lung Infectious Disease
Authors: Williams Andrew Evan , Edwards Lorna , Humphreys Ian Robert , Snelgrove Robert , Rae Aaron , Rappuoli Rino , Hussell Tracy 
Published: April 2014

Abstract
In a healthy individual, the lung contains few lymphoid cells. However, amplified immune responses, as exemplified during lung infection, can cause extensive tissue damage. We have previously demonstrated that one lung infection modulates the immunopathological outcome to a subsequent unrelated pathogen. Mimicking heterologous immunity may provide a means of enhancing both innate and acquired immunity. We now show that prior lung administration of a modified heat-labile toxin from Escherichia coli (LTK63) enhances immunity to respiratory syncytial virus, influenza virus, and the fungus Cryptococcus neoformans. Treatment with LTK63 decreased lung inflammation and tissue damage and improved the ability to resolve the infection. APCs expressing the activation markers MHC class II, CD80, and CD40 increased in number in the lung. LTK63 treatment increased the pathogen-specific IgA response in the nasal mucosa and simultaneously decreased inflammatory cytokine production (IFN-γ and TNF-α) after infection. The number of activated CD8+CD44+ T cells and the respiratory syncytial virus- or influenza-specific CD8-proliferative responses increased, although the total inflammatory infiltrate was reduced. LTK63 treatment matured lung APCs (LTK63 prevented efficient presentation of whole OVA to DO11.10 cells, whereas OVA peptide presentation was unaffected), enhanced immunity in both a Th1 and Th2 environment, was long lasting, and was not pathogen or host strain specific; the protective effects were partially independent of T and B cells. Innate imprinting by toxin-based immunotherapeutics may provide generic protection against infectious disease in the lung, without the need for coadministered pathogen-specific Ag.
Exploiting Type 3 Complement Receptor for TNF-α Suppression, Immune Evasion, and Progressive Pulmonary Fungal Infection
Authors: Brandhorst T. Tristan , Wüthrich Marcel , Finkel-Jimenez Bea , Warner Thomas , Klein Bruce S. 
Published: April 2014

Abstract
TNF-α is crucial in defense against intracellular microbes. Host immune cells use type 3 complement receptors (CR3) to regulate excess TNF-α production during physiological clearance of apoptotic cells. BAD1, a virulence factor of Blastomyces dermatitidis, is displayed on yeast and released during infection. BAD1 binds yeast to macrophages (Mφ) via CR3 and CD14 and suppresses TNF-α, which is required for resistance. We investigated whether blastomyces adhesin 1 (BAD1) exploits host receptors for immune deviation and pathogen survival. Soluble BAD1 rapidly entered Mφ, accumulated intracellularly by 10 min after introduction to cells, and trafficked to early and late endosomes. Inhibition of receptor recycling by monodansyl cadaverine blocked association of BAD1 with Mφ and reversed TNF-α suppression in vitro. Inhibition of BAD1 uptake with cytochalasin D and FcR-redirected delivery of soluble BAD1 as Ag-Ab complexes or of wild-type yeast opsonized with IgG similarly reversed TNF-α suppression. Hence, receptor-mediated entry of BAD1 is requisite in TNF-α suppression, and the route of entry is critical. Binding of soluble BAD1 to Mφ of CR3−/− and CD14−/− mice was reduced to 50 and 33%, respectively, of that in wild-type mice. Mφ of CR3−/− and CD14−/− mice resisted soluble BAD1 TNF-α suppression in vitro, but, in contrast to CR3−/− cells, CD14−/− cells were still subject to suppression mediated by surface BAD1 on wild-type yeast. CR3−/− mice resisted both infection and TNF-α suppression in vivo, in contrast to wild-type and CD14−/− mice. BAD1 of B. dermatitidis thus co-opts normal host cell physiology by exploiting CR3 to subdue TNF-α production and foster pathogen survival.
Helminth Antigens Modulate TLR-Initiated Dendritic Cell Activation
Authors: Kane Colleen M. , Cervi Laura , Sun Jie , McKee Amy S. , Masek Katherine S. , Shapira Sagi , Hunter Christopher A. , Pearce Edward J. 
Published: April 2014

AbstractThere is increasing awareness that helminth infections can ameliorate proinflammatory conditions. In part, this is due to their inherent ability to induce Th2 and, perhaps, regulatory T cell responses. However, recent evidence indicates that helminths also have direct anti-inflammatory effects on innate immune responses. In this study, we address this issue and show that soluble molecules from the eggs of the helminth parasite Schistosoma mansoni (SEA) suppress LPS-induced activation of immature murine dendritic cells, including MHC class II, costimulatory molecule expression, and IL-12 production. SEA-augmented LPS-induced production of IL-10 is in part responsible for the observed reduction in LPS-induced IL-12 production. However, analyses of IL-10−/− DC revealed distinct IL-10-independent suppressive effects of SEA. IL-10-independent mechanisms are evident in the suppression of TLR ligand-induced MAPK and NF-κB signaling pathways. Microarray analyses demonstrate that SEA alone uniquely alters the expression of a small subset of genes that are not up-regulated during conventional TLR-induced DC maturation. In contrast, the effects of SEA on TLR ligand-induced DC activation were striking: when mixed with LPS, SEA significantly affects the expression of &gt;100 LPS-regulated genes. These findings indicate that SEA exerts potent anti-inflammatory effects by directly regulating the ability of DC to respond to TLR ligands.
Reconstitution of Chemotactic Peptide-Induced Nicotinamide Adenine Dinucleotide Phosphate (Reduced) Oxidase Activation in Transgenic COS-phox Cells
Authors: He Rong , Nanamori Masakatsu , Sang Hairong , Yin Hong , Dinauer Mary C. , Ye Richard D. 
Published: April 2014

Abstract
A whole-cell-based reconstitution system was developed to study the signaling mechanisms underlying chemoattractant-induced activation of NADPH oxidase. This system takes advantage of the lack of formyl peptide receptor-mediated response in COS-phox cells expressing gp91phox, p22phox, p67phox, and p47phox, which respond to phorbol ester and arachidonic acid with O⨪2 production. By exogenous expression of signaling molecules enriched in neutrophils, we have identified several critical components for fMLP-induced NADPH oxidase activation. Expression of PKCδ, but not PKCα, -βII, and -ζ, is necessary for the COS-phox cells to respond to fMLP. A role of PKCδ in neutrophil NADPH oxidase was confirmed based on the ability of fMLP to induce PKCδ translocation and the sensitivity of fMLP-induced O⨪2 production to rottlerin, a PKCδ-selective inhibitor. Optimal reconstitution also requires phospholipase C-β2 and PI3K-γ. We found that formyl peptide receptor could use the endogenous Rac1 as well as exogenous Rac1 and Rac2 for NADPH oxidase activation. Exogenous expression of p40phox potentiated fMLP-induced O⨪2 production and raised the level of O⨪2 in unstimulated cells. Collectively, these results provide first direct evidence for reconstituting fMLP-induced O⨪2 production in a nonhemopoietic cell line, and demonstrate the requirement of multiple signaling components for optimal activation of NADPH oxidase by a chemoattractant.
Demonstration of the Involvement of Outer Surface Protein E Coiled Coil Structural Domains and Higher Order Structural Elements in the Binding of Infection-Induced Antibody and the Complement-Regulatory Protein, Factor H
Authors: McDowell John V. , Wolfgang Jill , Senty Lauren , Sundy Christina M. , Noto Michael J. , Marconi Richard T. 
Published: April 2014

Abstract
Factor H (fH) is an important regulator of the alternative complement cascade. Several human pathogens have been shown to bind fH to their surface, a process that facilitates immune evasion or cell to cell interaction. Among the pathogens that bind fH are some Borrelia species associated with Lyme disease and relapsing fever. The fH-binding proteins of the Lyme spirochetes form two classes (I and II). In Borrelia burgdorferi B31MI, class I includes the outer surface protein E (OspE) paralogs, L39, N38, and P38, whereas the class II group includes A68 and additional proteins that have not yet been identified. To identify the OspE determinants involved in fH and OspE-targeting infection-induced Ab (iAb) binding, deletion, random, and site-directed mutagenesis of L39 were performed. Mutations in several different regions of L39 abolished fH and or iAb binding, indicating that separable domains and residues of OspE are required for ligand binding. Some of the mutants that lost the ability to bind fH, iAb, or both had only a single amino acid change. Site-directed mutagenesis of three putative coiled coil motifs of OspE revealed that these higher order structures are required for fH binding but not for iAb binding. The data presented within demonstrate that the binding of fH and iAb to the OspE protein is mediated by higher order structures and protein conformation. These studies advance our understanding of fH binding as a virulence mechanism and facilitate ongoing efforts to use fH-binding proteins in the development of microbial vaccines.