bluuebunny/crossref_metadata_2025_split huggingface dataset:
Kinetics of MHC-CD8 Interaction at the T Cell Membrane
Authors: Huang Jun , Edwards Lindsay J. , Evavold Brian D. , Zhu Cheng 
Published: April 2014

Abstract
CD8 plays an important role in facilitating TCR-MHC interaction, promoting Ag recognition, and initiating T cell activation. MHC-CD8 binding kinetics have been measured in three dimensions by surface plasmon resonance technique using purified molecules. However, CD8 is a membrane-anchored, signaling kinase-linked, and TCR-associated molecule whose function depends on the cell membrane environment. Purified molecules lack their linkage to the membrane, which precludes interactions with other structures of the cell as well as signaling. Furthermore, three-dimensional binding in the fluid phase is biologically and physically distinct from two-dimensional binding across apposing cell membranes. As a first step toward characterizing the molecular interactions between T cells and APCs, we used a micropipette adhesion frequency assay to measure the adhesion kinetics of single mouse T cells interacting with single human RBCs coated with MHC. Using anti-TCR mAb we isolated and characterized the specific two-dimensional MHC-CD8 binding from the trimolecular TCR-MHC-CD8 interaction. The TCR-independent MHC-CD8 interaction has a very low affinity that depends on the MHC alleles, but not on the peptide complexed to the MHC and whether CD8 is an αα homodimer or an αβ heterodimer. Surprisingly, MHC-CD8 binding affinity varies with T cells from different TCR transgenic mice and these affinity differences were abolished by treatment with cholesterol oxidase to disrupt membrane rafts. These data highlight the relevance and importance of two-dimensional analysis of T cells and APCs and indicate that membrane rafts play an important role in modulating the affinity of cell-cell interactions.
Increased Phosphorylation of the Carboxyl-Terminal Domain of RNA Polymerase II and Loading of Polyadenylation and Cotranscriptional Factors Contribute to Regulation of the Ig Heavy Chain mRNA in Plasma Cells
Authors: Shell Scott A. , Martincic Kathleen , Tran Joseph , Milcarek Christine 
Published: April 2014

Abstract
B cells produce Ig H chain (IgH) mRNA and protein, primarily of the membrane-bound specific form. Plasma cells produce 20- to 50-fold higher amounts of IgH mRNA, most processed to the secretory specific form; this shift is mediated by substantial changes in RNA processing but only a small increase in IgH transcription rate. We investigated RNA polymerase II (RNAP-II) loading and phosphorylation of its C-terminal domain (CTD) on the IgG2a H chain gene, comparing two mouse cell lines representing B (A20) and plasma cells (AxJ) that express the identical H chain gene whose RNA is processed in different ways. Using chromatin immunoprecipitation and real-time PCR, we detected increased RNAP-II and Ser-2 and Ser-5 phosphorylation of RNAP-II CTD close to the IgH promoter in plasma cells. We detected increased association of several 3′ end-processing factors, ELL2 and PC4, at the 5′ end of the IgH gene in AxJ as compared with A20 cells. Polymerase progress and factor associations were inhibited by 5,6-dichlorobenzimidazole riboside, a drug that interferes with the addition of the Ser-2 to the CTD of RNAP-II. Taken together, these data indicate a role for CTD phosphorylation and polyadenylation/ELL2/PC4 factor loading on the polymerase in the choice of the secretory poly(A) site for the IgH gene.
Characterization of the Deregulated Immune Activation Occurring at Late Stages of Mycobacterial Infection in TNF-Deficient Mice
Authors: Flórido Manuela , Appelberg Rui 
Published: April 2014

Abstract
In the absence of TNF, mice infected with Mycobacterium avium suffer a peculiar disintegration of the granulomas, with extensive apoptosis and necrosis of their cells, occurring during the course of the infection and leading to the death of the animals within a few days of its onset. The survival time depends on the virulence of the infecting strain as well as on the dose and route of infection. Intravenously infected mice developed the typical lesions in hepatic granulomas whereas aerosol-infected animals developed them in the lung granulomas. At the onset of the development of pulmonary granuloma disintegration, extensive expansion of T cells, with intense up-regulation of activation markers, massive exacerbation of their ability to secrete IFN-γ, and increased cytotoxic activity of both CD4+ and CD8+ T cells were observed. Forced expression of Bcl2 did not prevent the early death of infected TNF-deficient mice leading merely to a modest increase in survival times. The expression of the FasL on T cells was not affected but there was an intense up-regulation of the TRAIL in T cells and, in particular, myeloid cells. We thus show that an exacerbated immune response occurs in TNF-deficient hosts during M. avium infections that leads to enhanced IFN-γ production and late up-regulation of TRAIL which may contribute to granuloma disintegration.
Novel Structural Determinants on SIRPα that Mediate Binding to CD47
Authors: Lee Winston Y. , Weber Dominique A. , Laur Oskar , Severson Eric A. , McCall Ingrid , Jen Rita P. , Chin Alex C. , Wu Tao , Gernet Kim M. , Parkos Charles A. 
Published: April 2014

Abstract
Signal regulatory proteins (SIRP-α, -β, and -γ) are important regulators of several innate immune functions that include leukocyte migration. Membrane distal (D1) domains of SIRPα and SIRPγ, but not SIRPβ, mediate binding to a cellular ligand termed CD47. Because the extracellular domains of all SIRPs are highly homologous, we hypothesized that some of the 16 residues unique to SIRPα.D1 mediate binding to CD47. By site-directed mutagenesis, we determined that SIRPα binding to CD47 is independent of N-glycosylation. We also identified three residues critical for CD47 binding by exchanging residues on SIRPα with corresponding residues from SIRPβ. Cumulative substitutions of the critical residues into SIRPβ resulted in de novo binding of the mutant protein to CD47. Homology modeling of SIRPα.D1 revealed topological relationships among critical residues and allowed the identification of critical residues common to SIRPα and SIRPβ. Mapping these critical residues onto the recently reported crystal structure of SIRPα.D1 revealed a novel region that is required for CD47 binding and is distinct and lateral to another putative CD47 binding site described on that crystal structure. The importance of this lateral region in mediating SIRPα.D1 binding to CD47 was confirmed by epitope mapping analyses of anti-SIRP Abs. These observations highlight a complex nature of the ligand binding requirements for SIRPα that appear to be dependent on two distinct but adjacent regions on the membrane distal Ig loop. A better understanding of the structural basis of SIRPα/CD47 interactions may provide insights into therapeutics targeting pathologic inflammation.
In Vivo Depletion of CD11c+ Cells Impairs Scrapie Agent Neuroinvasion from the Intestine
Authors: Raymond Claudine R. , Aucouturier Pierre , Mabbott Neil A. 
Published: April 2014

Abstract
Following oral exposure, some transmissible spongiform encephalopathy (TSE) agents accumulate first upon follicular dendritic cells (DCs) in the GALT. Studies in mice have shown that TSE agent accumulation in the GALT, in particular the Peyer’s patches, is obligatory for the efficient transmission of disease to the brain. However, the mechanism through which TSE agents are initially conveyed from the gut lumen to the GALT is not known. Studies have implicated migratory hemopoietic DCs in this process, but direct demonstration of their involvement in vivo is lacking. In this study, we have investigated the contribution of CD11c+ DCs in scrapie agent neuroinvasion through use of CD11c-diptheria toxin receptor-transgenic mice in which CD11c+ DCs can be specifically and transiently depleted. Using two distinct scrapie agent strains (ME7 and 139A scrapie agents), we show that when CD11c+ DCs were transiently depleted in the GALT and spleen before oral exposure, early agent accumulation in these tissues was blocked. In addition, CD11c+ cell depletion reduced susceptibility to oral scrapie challenge indicating that TSE agent neuroinvasion from the GALT was impaired. In conclusion, these data demonstrate that migratory CD11c+ DCs play a key role in the translocation of the scrapie agent from the gut lumen to the GALT from which neuroinvasion subsequently occurs.
Human Cytomegalovirus Differentially Controls B Cell and T Cell Responses through Effects on Plasmacytoid Dendritic Cells
Authors: Varani Stefania , Cederarv Madeleine , Feld Sari , Tammik Charlotte , Frascaroli Giada , Landini Maria P. , Söderberg-Nauclér Cecilia 
Published: April 2014

Abstract
Plasmacytoid dendritic cells (PDCs), the main producers of type I IFN in response to viral infection, are essential in antiviral immunity. In this study, we assessed the effect of human CMV (HCMV) infection on PDC function and on downstream B and T cell responses in vitro. HCMV infection of human PDCs was nonpermissive, as immediate-early but not late viral Ags were detected. HCMV led to partial maturation of PDCs and up-regulated MHC class II and CD83 molecules but not the costimulatory molecules CD80 and CD86. Regardless of viral replication, PDCs secreted cytokines after contact with HCMV, including IFN-α secretion that was blocked by inhibitory CpG, suggesting an engagement of the TLR7 and/or TLR9 pathways. In the presence of B cell receptor stimulation, soluble factors produced by HCMV-matured PDCs triggered B cell activation and proliferation. Through PDC stimulation, HCMV prompted B cell activation, but only induced Ab production in the presence of T cells or T cell secreted IL-2. Conversely, HCMV hampered the allostimulatory ability of PDCs, leading to decreased proliferation of CD4+ and CD8+ T cells. These findings reveal a novel mechanism by which HCMV differentially controls humoral and cell-mediate immune responses through effects on PDCs.
Galectin-3 Functions as an Adhesion Molecule to Support Eosinophil Rolling and Adhesion under Conditions of Flow
Authors: Rao Savita P. , Wang Zhuangzhi , Zuberi Riaz I. , Sikora Lyudmila , Bahaie Nooshin S. , Zuraw Bruce L. , Liu Fu-Tong , Sriramarao P. 
Published: April 2014

AbstractAllergic inflammation involves the mobilization and trafficking of eosinophils to sites of inflammation. Galectin-3 (Gal-3) has been shown to play a critical role in eosinophil recruitment and airway allergic inflammation in vivo. The role played by Gal-3 in human eosinophil trafficking was investigated. Eosinophils from allergic donors expressed elevated levels of Gal-3 and demonstrated significantly increased rolling and firm adhesion on immobilized VCAM-1 and, more surprisingly, on Gal-3 under conditions of flow. Inhibition studies with specific mAbs as well as lactose demonstrated that: 1) eosinophil-expressed Gal-3 mediates rolling and adhesion on VCAM-1; 2) α4 integrin mediates eosinophil rolling on immobilized Gal-3; and 3) eosinophil-expressed Gal-3 interacts with immobilized Gal-3 through the carbohydrate recognition domain of Gal-3 during eosinophil trafficking. These findings were further confirmed using inflamed endothelial cells. Interestingly, Gal-3 was found to bind to α4 integrin by ELISA, and the two molecules exhibited colocalized expression on the cell surface of eosinophils from allergic donors. These findings suggest that Gal-3 functions as a cell surface adhesion molecule to support eosinophil rolling and adhesion under conditions of flow.
Heme Oxygenase-1 Inhibits the Expression of Adhesion Molecules Associated with Endothelial Cell Activation via Inhibition of NF-κB RelA Phosphorylation at Serine 276
Authors: Seldon Mark P. , Silva Gabriela , Pejanovic Nadja , Larsen Rasmus , Gregoire Isabel Pombo , Filipe Josina , Anrather Josef , Soares Miguel P. 
Published: April 2014

Abstract
Heme oxygenase-1 (HO-1; encoded by the Hmox1 gene) catalyzes the degradation of free heme into biliverdin, via a reaction that releases iron (Fe) and carbon monoxide. We report that HO-1 down-regulates the proinflammatory phenotype associated with endothelial cell (EC) activation by reducing intracellular nonprotein-bound Fe (labile Fe). EC isolated from Hmox1−/− mice have higher levels of intracellular labile Fe and reactive oxygen species (ROS) as compared with EC isolated from Hmox1+/+ mice. Basal and TNF-induced expression of VCAM-1, ICAM-1, and E-selectin were increased in Hmox1−/− vs Hmox1+/+ EC, an effect reversed by Fe chelation using deferoxamine mesylate (DFO). Fe chelation inhibits TNF-driven transcription of Vcam-1, Icam-1, and E-selectin, as assessed using luciferase reporter assays. This effect is associated with inhibition of the transcription factor NF-κB via a mechanism that is not associated with the inhibition of IκBα phosphorylation/degradation or NF-κB (i.e., RelA) nuclear translocation, although it affects very modestly NF-κB binding to DNA κB consensus sequences in the Vcam-1 and E-selectin promoters. HO-1 inhibits NF-κB (i.e., RelA) phosphorylation at Ser276, a phosphoacceptor that is critical to sustain TNF-driven NF-κB activity in EC. This effect was mimicked by Fe chelation as well as by antioxidants (N-acetylcysteine). In conclusion, we demonstrate a novel mechanism via which HO-1 down-modulates the proinflammatory phenotype of activated EC, i.e., the inhibition of RelA phosphorylation at Ser276.
Amelioration of Chronic Murine Colitis by Peptide-Mediated Transduction of the IκB Kinase Inhibitor NEMO Binding Domain Peptide
Authors: Davé Shaival H. , Tilstra Jeremy S. , Matsuoka Katsuyoshi , Li Fengling , Karrasch Thomas , Uno Jennifer K. , Sepulveda Antonia R. , Jobin Christian , Baldwin Albert S. , Robbins Paul D. , Plevy Scott E. 
Published: April 2014

Abstract
The NF-κB family of transcription factors is a central regulator of chronic inflammation. The phosphorylation of IκB proteins by the IκB kinase (IKK) complex (IKKα, IKKβ, and NF-κB essential modulator or NEMO) is a key step in NF-κB activation. Peptides corresponding to the NEMO binding domain (NBD) of IKK blocks NF-κB activation without inhibiting basal NF-κB activity. In this report, we determined the effects of the IKK inhibitor peptide (NBD) in a model of spontaneously occurring chronic murine colitis, the IL-10-deficient (IL-10−/−) mouse. Using a novel cationic peptide transduction domain (PTD) consisting of eight lysine residues (8K), we were able to transduce the NBD peptide into cells and tissues. In a NF-κB reporter system, 8K-NBD dose-dependently inhibits TNF-induced NF-κB activation. Furthermore, 8K-NBD inhibited nuclear translocation of NF-κB family members. In NF-κBEGFP knock-in mice, 8K-NBD inhibited LPS-activated NF-κB (EGFP activity) in the ileum but did not inhibit basal NF-κB in Peyer’s patches. IL-10−/− mice treated systemically with 8K-NBD demonstrate amelioration of established colitis, decreased NF-κB activation in the lamina propria, and a reduction in spontaneous intestinal IL-12 p40, TNF, IFN-γ, and IL-17 production. These results demonstrate that inhibitors of IKK, in particular a PTD-NBD peptide, may be therapeutic in the treatment of inflammatory bowel disease.
A Complement C3 Inhibitor Specifically Targeted to Sites of Complement Activation Effectively Ameliorates Collagen-Induced Arthritis in DBA/1J Mice
Authors: Song Hongbin , Qiao Fei , Atkinson Carl , Holers V. Michael , Tomlinson Stephen 
Published: April 2014

Abstract
Collagen-induced arthritis (CIA) represents an animal model of autoimmune polyarthritis with similarities to human rheumatoid arthritis, and therapy with various systemic complement-inhibitory proteins has been investigated in this model with varying results. We investigated the use of complement receptor 2 (CR2)-Crry, a complement inhibitor with the ability to target C3 breakdown products deposited in a rheumatic joint. Following induction of CIA in DBA/1J mice, animals were treated with either PBS or CR2-Crry (every other day, every 4 days, or with a single injection). The severity of clinical disease was significantly reduced in all CR2-Crry-treated groups compared with controls. Joints from mice receiving multiple doses of CR2-Crry showed significantly decreased inflammatory cell infiltrate, cartilage damage, pannus formation, and bone damage. CR2-Crry treatment also significantly decreased production of anti-collagen IgG and the inflammatory cytokines TNF-α and IL-1β. IL-10 and IL-1Ra levels were increased in CR2-Crry-treated mice. CR2-Crry localized preferentially in the joints of mice with CIA. Analysis of IgG and C3 deposition in the joints of treated animals indicated that both complement regulation and the modulation of anti-collagen Ab production contributed to the protective effects of CR2-Crry. Of interest, a previous study reported that Crry-Ig, an untargeted counterpart of CR2-Crry, had minimal effect on disease, even when administered at a sufficiently high dose to maintain chronic complement inhibition.
Histamine Directly and Synergistically with Lipopolysaccharide Stimulates Cyclooxygenase-2 Expression and Prostaglandin I2 and E2 Production in Human Coronary Artery Endothelial Cells
Authors: Tan Xiaoyu , Essengue Suzanne , Talreja Jaya , Reese Jeff , Stechschulte Daniel J. , Dileepan Kottarappat N. 
Published: April 2014

Abstract
Although histamine plays an essential role in inflammation, its influence on cyclooxygenases (COX) and prostanoid homeostasis is not well understood. In this study, we investigated the effects of histamine on the expression of COX-1 and COX-2 and determined their contribution to the production of PGE2, prostacyclin (PGI2), and thromboxane A2 in human coronary artery endothelial cells (HCAEC). Incubation of HCAEC monolayers with histamine resulted in marked increases in the expression of COX-2 and production of PGI2 and PGE2 with no significant change in the expression of COX-1. Histamine-induced increases in PGI2 and PGE2 production were due to increased expression and function of COX-2 because gene silencing by small interfering RNA or inhibition of the catalytic activity by a COX-2 inhibitor blocked prostanoid production. The effects of histamine on COX-2 expression and prostanoid production were mediated through H1 receptors. In addition to the direct effect, histamine was found to amplify LPS-stimulated COX-2 expression and PGE2 and PGI2 production. In contrast, histamine did not stimulate thromboxane A2 production in resting or LPS-activated HCAEC. Histamine-induced increases in the production of PGE2 and PGI2 were associated with increased expression of mRNA encoding PGE2 and PGI2 synthases. The physiological role of histamine on the regulation of COX-2 expression in the vasculature is indicated by the findings that the expression of COX-2 mRNA, but not COX-1 mRNA, was markedly reduced in the aortic tissues of histidine decarboxylase null mice. Thus, histamine plays an important role in the regulation of COX-2 expression and prostanoid homeostasis in vascular endothelium.
FcγRIIa Genotype Predicts Progression of HIV Infection
Authors: Forthal Donald N. , Landucci Gary , Bream Jay , Jacobson Lisa P. , Phan Tran B. , Montoya Benjamin 
Published: April 2014

Abstract
Polymorphisms in FcγR genes are associated with susceptibility to or severity of a number of autoimmune and infectious diseases. We found that HIV-infected men in the Multicenter AIDS Cohort Study with the FcγRIIa RR genotype progressed to a CD4+ cell count of &lt;200/mm3 at a faster rate than individuals with the RH or HH genotypes (relative hazard = 1.6; p = 0.0001). However, progression to AIDS (using the broad definition of either a CD4+ cell count &lt;200/mm3 or development of an AIDS-defining illness) was less impacted by FcγRIIa genotype, largely because HH homozygotes had an increased risk of Pneumocystis jiroveci pneumonia as an AIDS-defining illness. We also showed that chronically infected subjects develop a substantial anti-gp120-specific IgG2 response. Moreover, HIV-1 immune complexes are more efficiently internalized by monocytes from HH subjects compared with RR subjects, likely because of the presence of IgG2 in the complexes. Finally, the FcγRIIIa F/V gene polymorphism was not associated with progression of HIV infection, but, as demonstrated previously, did predict the risk of Kaposi’s sarcoma. These results demonstrate the importance of FcγRs in AIDS pathogenesis and point toward a critical role for interactions between FcγRs and immune complexes in disease progression.
Cross-Reactive CD4+ T Cells against One Immunodominant Tumor-Derived Epitope in Melanoma Patients
Authors: Kudela Pavol , Janjic Bratislav , Fourcade Julien , Castelli Florence , Andrade Pedro , Kirkwood John M. , El-Hefnawy Talal , Amicosante Massimo , Maillere Bernard , Zarour Hassane M. 
Published: April 2014

Abstract
TCRs exhibit a high degree of specificity but may also recognize multiple and distinct peptide-MHC complexes, illustrating the so-called cross-reactivity of TCR-peptide-MHC recognition. In this study, we report the first evidence of CD4+ T cells recognizing the same tumor peptide-epitope from NY-ESO-1, in the context of multiple HLA-DR and HLA-DP molecules. These cross-reactive CD4+ T cells recognized not only autologous but also allogenic dendritic cells previously loaded with the relevant protein (i.e., the normally processed and presented epitope). Using clonotypic real-time RT-PCR, we have detected low frequencies of CD4+ T cells expressing one cross-reactive TCR from circulating CD4+ T cells of patients with stage IV melanoma either spontaneously or after immunization but not in normal donors. The maintenance of cross-reactive tumor Ag-specific CD4+ T cells in PBLs of cancer patients required the presence of tumor Ag/epitope in the context of the MHC molecule used to prime the Ag-specific CD4+ T cells. Our findings have significant implications for the optimization of TCR gene transfer immunotherapies widely applicable to cancer patients.
CD4+CD25int T Cells in Inflammatory Diseases Refractory to Treatment with Glucocorticoids
Authors: Lee Richard W. J. , Creed Thomas J. , Schewitz Lauren P. , Newcomb Paul V. , Nicholson Lindsay B. , Dick Andrew D. , Dayan Colin M. 
Published: April 2014

Abstract
Up to 30% of patients with autoimmune, allergic, and lymphoproliferative diseases are refractory to glucocorticoid therapy. The present study was undertaken to investigate whether such steroid resistance (SR) is limited to a subpopulation of CD4+ T cells and, as IL-2 is a putative driver of SR, whether T cell SR is associated with CD25 expression. We show that SR patients have a characteristic subgroup of activated CD4+ T cells that continue to proliferate despite exposure to high-dose Dexamethasone (Dex), demonstrate that CD4+CD25− cells are exquisitely sensitive to Dex whereas CD4+CD25int cells are highly SR, and further find that the combination of an anti-CD25 mAb with Dex enhances suppression of T cell proliferation compared with each agent alone. We therefore conclude that SR is not a general property of all lymphocytes but resides in T cell subpopulations, which are prevalent in SR patients and express intermediary levels of CD25. As a result, we propose a new paradigm for SR disease in which glucocorticoid therapy positively selects SR cells, generating a population of drug-resistant lymphocytes that perpetuate on-going inflammation.