bluuebunny/crossref_metadata_2025_split huggingface dataset:
A20 Negatively Regulates T Cell Receptor Signaling to NF-κB by Cleaving Malt1 Ubiquitin Chains
Authors: Düwel Michael , Welteke Verena , Oeckinghaus Andrea , Baens Mathijs , Kloo Bernhard , Ferch Uta , Darnay Bryant G. , Ruland Jürgen , Marynen Peter , Krappmann Daniel 
Published: June 2009

Abstract
The Carma1-Bcl10-Malt1 signaling module bridges TCR signaling to the canonical IκB kinase (IKK)/NF-κB pathway. Covalent attachment of regulatory ubiquitin chains to Malt1 paracaspase directs TCR signaling to IKK activation. Further, the ubiquitin-editing enzyme A20 was recently suggested to suppress T cell activation, but molecular targets for A20 remain elusive. In this paper, we show that A20 regulates the strength and duration of the IKK/NF-κB response upon TCR/CD28 costimulation. By catalyzing the removal of K63-linked ubiquitin chains from Malt1, A20 prevents sustained interaction between ubiquitinated Malt1 and the IKK complex and thus serves as a negative regulator of inducible IKK activity. Upon T cell stimulation, A20 is rapidly removed and paracaspase activity of Malt1 has been suggested to cleave A20. Using antagonistic peptides or reconstitution of Malt1−/− T cells, we show that Malt1 paracaspase activity is required for A20 cleavage and optimal IL-2 production, but dispensable for initial IKK/NF-κB signaling in CD4+ T cells. However, proteasomal inhibition impairs A20 degradation and impedes TCR/CD28-induced IKK activation. Taken together, A20 functions as a Malt1 deubiquitinating enzyme and proteasomal degradation and de novo synthesis of A20 contributes to balance TCR/CD28-induced IKK/NF-κB signaling.
Selective Autoantibody Production against CCL3 Is Associated with Human Type 1 Diabetes Mellitus and Serves As a Novel Biomarker for Its Diagnosis
Authors: Shehadeh Naim , Pollack Shirly , Wildbaum Gizi , Zohar Yaniv , Shafat Itay , Makhoul Reem , Daod Essam , Hakim Fahed , Perlman Rina , Karin Nathan 
Published: June 2009

Abstract
We have recently demonstrated that patients suffering from chronic autoimmune diseases develop an autoantibody response against key mediators that participate in the initiation and progression of these diseases. In this paper, we show that patients with type 1 diabetes mellitus (T1DM), but not those suffering from several other inflammatory autoimmune diseases, display a selective autoantibody titer to a single CC chemokine named CCL3. From the diagnostic point we show that this response could be used as a biomarker for diagnosis of T1DM, a disease that is currently diagnosed by autoantibodies to competitive anti-insulin Abs, islet cell Abs, and glutamic acid decarboxylase Abs. We show that our currently suggested biomarker is more reliable than each of the above alone, including diagnosis of T1DM at its preclinical stage, and could therefore be used as a novel way for diagnosis of T1DM. These Abs were found to be neutralizing Abs. It is possible, though hard to prove, that these Abs participate in the natural regulation of the human disease. Hence, it has previously been shown by others that selective neutralization of CCL3 suppresses T1DM in NOD mice. Theses results together with ours suggest CCL3 as a preferential target for therapy of T1DM.
Differential Expression of Adenosine A3 Receptors Controls Adenosine A2A Receptor-Mediated Inhibition of TLR Responses in Microglia
Authors: van der Putten Céline , Zuiderwijk-Sick Ella A. , van Straalen Linda , de Geus Eveline D. , Boven Leonie A. , Kondova Ivanela , IJzerman Ad P. , Bajramovic Jeffrey J. 
Published: June 2009

AbstractMicroglia activation is a prominent feature in many neuroinflammatory disorders. Unrestrained activation can generate a chronic inflammatory environment that might lead to neurodegeneration and autoimmunity. Extracellular adenosine modulates cellular activation through adenosine receptor (ADORA)-mediated signaling. There are four ADORA subtypes that can either increase (A2A and A2B receptors) or decrease (A1 and A3 receptors) intracellular cyclic AMP levels. The expression pattern of the subtypes thus orchestrates the cellular response to extracellular adenosine. We have investigated the expression of ADORA subtypes in unstimulated and TLR-activated primary rhesus monkey microglia. Activation induced an up-regulation of A2A and a down-regulation of A3 receptor (A3R) levels. The altered ADORA-expression pattern sensitized microglia to A2A receptor (A2AR)-mediated inhibition of subsequent TLR-induced cytokine responses. By using combinations of subtype-specific agonists and antagonists, we revealed that in unstimulated microglia, A2AR-mediated inhibitory signaling was effectively counteracted by A3R-mediated signaling. In activated microglia, the decrease in A3R-mediated signaling sensitized them to A2AR-mediated inhibitory signaling. We report a differential, activation state-specific expression of ADORA in microglia and uncover a role for A3R as dynamically regulated suppressors of A2AR-mediated inhibition of TLR-induced responses. This would suggest exploration of combinations of A2AR agonists and A3R antagonists to dampen microglial activation during chronic neuroinflammatory conditions.
Endotoxin Augmented Antigen-Induced Th1 Cell Trafficking Amplifies Airway Neutrophilic Inflammation
Authors: Mikhak Zamaneh , Farsidjani Alireza , Luster Andrew D. 
Published: June 2009

Abstract
CD4+ Th1 cells play a critical role in orchestrating host defense against pathogens and in the pathogenesis of many immune-mediated diseases. The control of Th1 cell trafficking into sites of infection and inflammation is an important determinant of Th1 cell function. We have previously shown that trafficking of adoptively transferred Ag-specific Th1 cells into the lung following airway Ag challenge depends on CXCR3 expression on Th1 cells and STAT1-inducible CXCR3 ligands in the lung. In this study, we show that LPS alters the mechanisms of Th1 cell recruitment. After a single intranasal dose of LPS, trafficking of adoptively transferred Ag-specific Th1 cell into the lung in response to airway Ag challenges was no longer dependent on CXCR3 and its ligands and instead was mediated through additional Gαi-coupled chemoattractant receptor pathways, including CCR5. In addition, LPS markedly increased the magnitude of Ag-specific Th1 cell homing into the airways following airway Ag challenges. The increased trafficking of Ag-activated Th1 cells, in turn, dramatically amplified LPS-induced airway neutrophilic infiltration by maintaining high levels of the neutrophil active chemokines, KC and MIP-2, through an IFN-γ dependent mechanism. Therefore, LPS increases Ag-specific Th1 cell trafficking into the airways and Ag-specific Th1 cells amplify the airway neutrophilic inflammatory response initiated by LPS. This reciprocal interaction between LPS and Ag-activated Th1 cells represents a collaborative connection between the innate and adaptive arms of the immune system.
Protective Role for Protease-Activated Receptor-2 against Influenza Virus Pathogenesis via an IFN-γ-Dependent Pathway
Authors: Khoufache Khaled , LeBouder Fanny , Morello Eric , Laurent Fabrice , Riffault Sabine , Andrade-Gordon Patricia , Boullier Severine , Rousset Perrine , Vergnolle Nathalie , Riteau Béatrice 
Published: June 2009

Abstract
Protease-activated receptor-2 (PAR2), a receptor highly expressed in the respiratory tract, can influence inflammation at mucosal surfaces. Although the effects of PAR2 in the innate immune response to bacterial infection have been documented, knowledge of its role in the context of viral infection is lacking. We thus investigated the role of PAR2 in influenza pathogenesis in vitro and in vivo. In vitro, stimulation of PAR2 on epithelial cells inhibited influenza virus type A (IAV) replication through the production of IFN-γ. In vivo, stimulation of PAR2 using specific agonists protected mice from IAV-induced acute lung injury and death. This effect correlated with an increased clearance of IAV in the lungs associated with increased IFN- γ production and a decreased presence of neutrophils and RANTES release in bronchoalveolar fluids. More importantly, the protective effect of the PAR2 agonist was totally abrogated in IFN- γ-deficient mice. Finally, compared with wild-type mice, PAR2-deficient mice were more susceptible to IAV infection and displayed more severe lung inflammation. In these mice higher neutrophil counts and increased RANTES concentration but decreased IFN- γ levels were observed in the bronchoalveolar lavages. Collectively, these results showed that PAR2 plays a protective role during IAV infection through IFN-γ production and decreased excessive recruitment of inflammatory cells to lung alveoli.
Increase in ALK1/ALK5 Ratio as a Cause for Elevated MMP-13 Expression in Osteoarthritis in Humans and Mice
Authors: Blaney Davidson Esmeralda N. , Remst Dennis F. G. , Vitters Elly L. , van Beuningen Henk M. , Blom Arjen B. , Goumans Marie-Jose , van den Berg Wim B. , van der Kraan Peter M. 
Published: June 2009

AbstractDuring osteoarthritis (OA) chondrocytes show deviant behavior resembling terminal differentiation of growth-plate chondrocytes, characterized by elevated MMP-13 expression. The latter is also a hallmark for OA. TGF-β is generally thought to be a protective factor for cartilage, but it has also displayed deleterious effects in some studies. Recently, it was shown that besides signaling via the ALK5 (activin-like kinase 5) receptor, TGF-β can also signal via ALK1, thereby activating Smad1/5/8 instead of Smad2/3. The Smad1/5/8 route can induce chondrocyte terminal differentiation. Murine chondrocytes stimulated with TGF-β activated the ALK5 receptor/Smad2/3 route as well as the ALK1/Smad1/5/8 route. In cartilage of mouse models for aging and OA, ALK5 expression decreased much more than ALK1. Thus, the ALK1/ALK5 ratio increased, which was associated with changes in the respective downstream markers: an increased Id-1 (inhibitor of DNA binding-1)/PAI-1 (plasminogen activator inhibitor-1) ratio. Transfection of chondrocytes with adenovirus overexpressing constitutive active ALK1 increased MMP-13 expression, while small interfering RNA against ALK1 decreased MMP-13 expression to nondetectable levels. Adenovirus overexpressing constitutive active ALK5 transfection increased aggrecan expression, whereas small interfering RNA against ALK5 resulted in increased MMP-13 expression. Moreover, in human OA cartilage ALK1 was highly correlated with MMP-13 expression, whereas ALK5 correlated with aggrecan and collagen type II expression, important for healthy cartilage. Collectively, we show an age-related shift in ALK1/ALK5 ratio in murine cartilage and a strong correlation between ALK1 and MMP-13 expression in human cartilage. A change in balance between ALK5 and ALK1 receptors in chondrocytes caused changes in MMP-13 expression, thereby causing an OA-like phenotype. Our data suggest that dominant ALK1 signaling results in deviant chondrocyte behavior, thereby contributing to age-related cartilage destruction and OA.
Interactions of α-, β-, and θ-Defensins with Influenza A Virus and Surfactant Protein D
Authors: Doss Mona , White Mitchell R. , Tecle Tesfaldet , Gantz Donald , Crouch Erika C. , Jung Grace , Ruchala Piotr , Waring Alan J. , Lehrer Robert I. , Hartshorn Kevan L. 
Published: June 2009

Abstract
We have reported that the α-defensins human neutrophil peptides (HNP)-1 and HNP-2 neutralize and aggregate influenza A virus (IAV) and promote uptake of IAV by neutrophils. These α-defensins were also shown to bind to surfactant protein (SP)-D and reduce its antiviral activity. In this study, we examined retrocyclin (RC)1 and RC2, humanized versions of the antiviral θ-defensins found in the leukocytes of certain nonhuman primates. RC1 was just as effective as HNP-1–3 in neutralizing IAV, and RC2 and RC101 (an analog of RC1) were more effective. In contrast, human β-defensins (HBDs) showed less neutralizing activity. Human defensins 5 and 6 (mainly produced by intestinal Paneth cells) had viral neutralizing activity similar to HNP-1–3. Like HNP-1–3, RCs induced viral aggregation and promoted the uptake of IAV by neutrophils. We used surface plasmon resonance to evaluate binding of defensins to SP-D. HBDs, HD6, and HNP-4 bound minimally to SP-D. HNP-1–3 and RCs bound SP-D with high affinity; however, unlike HNP-1 and HNP-2, RCs did not inhibit SP-D antiviral activity. HBDs also did not inhibit antiviral activity of SP-D. Given their strong neutralizing activity and compatibility with SP-D, RCs may provide attractive prototypes for designing therapeutics that can prevent or treat respiratory infections caused by IAV.
Gene Disruption Study Reveals a Nonredundant Role for TRIM21/Ro52 in NF-κB-Dependent Cytokine Expression in Fibroblasts
Authors: Yoshimi Ryusuke , Chang Tsung-Hsien , Wang Hongsheng , Atsumi Toru , Morse Herbert C. , Ozato Keiko 
Published: June 2009

Abstract
The tripartite motif (TRIM) family member, TRIM21, is an E3 ubiquitin ligase for IFN regulatory factor (IRF)3 and IRF8 that functions in both innate and acquired immunity. It is also an autoantigen known as Ro52/SS-A. The function of TRIM21 in vivo, however, has remained elusive. We generated Trim21−/− mice with the Trim21 gene replaced by an enhanced GFP (EGFP) reporter. EGFP expression analyses showed that Trim21 was widely expressed in many tissues, with the highest levels in immune cells. Studies of Trim21−/− embryonic fibroblasts demonstrated that TLR-mediated induction of proinflammatory cytokines, including IL-1β, IL-6, TNF-α, and CXCL10, was consistently up-regulated relative to wild-type cells. Reporter analyses demonstrated that TLR-mediated NF-κB activation was higher in Trim21−/− cells than in wild-type cells, most likely accounting for their enhanced cytokine expression. In contrast, functional analyses of immune cells from Trim21−/− mice revealed no abnormalities in their composition or function, even though ubiquitylation of IRF3 and IRF8 was impaired. These results suggested possible redundancies in activities mediated by TRIM21. In keeping with this concept, we found that a number of TRIM family members were up-regulated in Trim21−/− cells. Taken together, these findings demonstrate that TRIM21 plays a previously unrecognized role in the negative regulation of NF-κB-dependent proinflammatory cytokine responses, and suggest that multiple TRIM proteins contribute to the maintenance of functional equilibrium in inflammatory responses, in part through functional redundancy.
Engineering Human IgG1 Affinity to Human Neonatal Fc Receptor: Impact of Affinity Improvement on Pharmacokinetics in Primates
Authors: Yeung Yik Andy , Leabman Maya K. , Marvin Jonathan S. , Qiu Julia , Adams Camellia W. , Lien Samantha , Starovasnik Melissa A. , Lowman Henry B. 
Published: June 2009

Abstract
The pH-dependent binding of Igs to the neonatal FcR (FcRn) plays a critical role in the in vivo homeostasis of IgGs. Modulating the interaction between Fc and FcRn through protein engineering is one method for improving the pharmacokinetics of therapeutic Abs. Recent studies disputed the direct relationship between increasing FcRn affinity and improved pharmacokinetic properties. In this work, we studied the pharmacokinetics of two human IgG1 Fc variants in cynomolgus monkey to further clarify the affinity-pharmacokinetic relationship. First, we report a number of novel Fc point mutations and combination variants, including some with primate-specific FcRn-binding improvements. By studying these variants along with some previously described variants across a wide range of affinities, we discovered a direct correlation of pH 6 affinity improvements with neutral pH improvements, suggesting that all of the tested variants exhibit similar pH dependency in FcRn binding. We then evaluated the pharmacokinetics of variants N434A and N434W, which, respectively, gave ∼4- and 80-fold improvements in pH 6-binding affinity to both human and nonhuman primate FcRn. Surprisingly, clearance of N434W was similar to that of wild type. N434W is the first variant studied in primates that exhibits significant binding to FcRn at pH 7.4, and its clearance substantiates the principle that too much affinity improvement, i.e., beyond that of N434W, does not yield improved pharmacokinetics. In contrast, N434A exhibited a ∼2-fold decrease in clearance in cynomolgus monkey, supporting the notion that modest increases in pH 6 FcRn affinity can result in improved pharmacokinetics in primates.
Scabies Mite Inactivated Serine Protease Paralogs Inhibit the Human Complement System
Authors: Bergström Frida C. , Reynolds Simone , Johnstone Masego , Pike Robert N. , Buckle Ashley M. , Kemp David J. , Fischer Katja , Blom Anna M. 
Published: June 2009

Abstract
Infestation of skin by the parasitic itch mite Sarcoptes scabiei afflicts 300 million people worldwide and there is a need for novel and efficient therapies. We have previously identified a multigene family of serine proteases comprising multiple catalytically inactive members (scabies mite-inactivated protease paralogs (SMIPPs)), which are secreted into the gut of S. scabiei. SMIPPs are located in the mite gut and in feces excreted into the upper epidermis. Scabies mites feed on epidermal protein, including host plasma; consequently, they are exposed to host defense mechanisms both internally and externally. We found that two recombinantly expressed SMIPPs inhibited all three pathways of the human complement system. Both SMIPPs exerted their inhibitory action due to binding of three molecules involved in the three different mechanisms which initiate complement: C1q, mannose-binding lectin, and properdin. Both SMIPPs bound to the stalk domains of C1q, possibly displacing or inhibiting C1r/C1s, which are associated with the same domain. Furthermore, we found that binding of both SMIPPs to properdin resulted in prevention of assembly of the alternative pathway convertases. However, the SMIPPs were not able to dissociate already formed convertases. Immunohistochemical staining demonstrated the presence of C1q in the gut of scabies mites in skin burrows. We propose that SMIPPs minimize complement-mediated gut damage and thus create a favorable environment for the scabies mites.
CXCR4 Expression Functionally Discriminates Centroblasts versus Centrocytes within Human Germinal Center B Cells
Authors: Caron Gersende , Le Gallou Simon , Lamy Thierry , Tarte Karin , Fest Thierry 
Published: June 2009

Abstract
The human germinal center is a highly dynamic structure where B cells conduct their terminal differentiation and traffic following chemokine gradients. The rapidly dividing centroblasts and the nondividing centrocytes represent the two major B cell subsets present in germinal center and also the most common normal counterparts for a majority of lymphomas. CD77 expression was previously associated to proliferating centroblasts undergoing somatic hypermutation, but data from transcriptional studies demonstrate that CD77 is not a reliable marker to discriminate human centroblasts from centrocytes. Herein we were able for the first time to separate these two subpopulations based on the expression of the chemokine receptor CXCR4 allowing their characterization. Phenotypic and functional features were especially explored, giving an accurate definition of CXCR4+ centroblasts compared with CXCR4− centrocytes. We show that CXCR4+ and CXCR4− germinal center B cells present a clear dichotomy in terms of proliferation, transcription factor expression, Ig production, and somatic hypermutation regulation. Microarray analysis identified an extensive gene list segregating these B cells, including highly relevant genes according to previous knowledge. By gene set enrichment analysis we demonstrated that the centroblastic gene expression signature was significantly enriched in Burkitt’s lymphomas. Collectively, our findings show that CXCR4 expression can properly separate human centroblasts from centrocytes and offer now the possibility to have purified normal counterparts of mature B cell-derived malignancies.
Cutting Edge: Primary and Secondary Effects of CD19 Deficiency on Cells of the Marginal Zone
Authors: You Yuying , Zhao Hong , Wang Yue , Carter Robert H. 
Published: June 2009

Abstract
Marginal zone (MZ) B cells are absent in CD19−/− mice. Possible causes include an intrinsic defect in B cells and/or a secondary defect in the extrinsic MZ microenvironment as a result of changes in B cell differentiation in mice lacking CD19. Cells in the MZ also include MZ macrophages (MZM) and MZ dendritic cells (DC). Although CD19 is only expressed on B cells, SIGN-R1+ MZM are absent and CD11c+ MZ DC distribution is abnormal in CD19−/− mice. Adoptively transferred B cells from normal mice are able to reconstitute MZ B cells in CD19−/− mice. In contrast, CD19−/− B cells could not enter the MZ of the normal mice. Furthermore, MZM distribution and MZ DC distribution are restored following MZ B cell reconstitution in CD19−/− mice. Thus, MZ B cells are required for MZM differentiation and MZ DC localization, but the deficiency of MZ B cells in CD19−/− mice is caused by a defect of intrinsic B cell signaling.
Association of FcγRIIa (CD32a) with Lipid Rafts Regulates Ligand Binding Activity
Authors: Bournazos Stylianos , Hart Simon P. , Chamberlain Luke H. , Glennie Martin J. , Dransfield Ian 
Published: June 2009

Abstract
Binding of Igs to myeloid cells via FcR is a key event in the control of innate and acquired immunity. FcγRIIa (CD32a) is a receptor for multivalent IgG expressed predominantly by myeloid cells, and its association with microdomains rich in cholesterol and sphingolipids, termed as lipid rafts, has been reported to be essential for efficient signaling. However, for many myeloid cell types, ligand binding to CD32a is suppressed by as yet undefined mechanisms. In this study, we have examined the role of CD32a-lipid raft interactions in the regulation of IgG binding to CD32a. Disruption of lipid raft structure following depletion or sequestration of membrane cholesterol greatly inhibited CD32a-mediated IgG binding. Furthermore, specific CD32a mutants, which show reduced association with lipid rafts (A224S and C241A), displayed decreased levels of IgG binding compared with wild-type CD32a. In contrast, constitutively lipid raft-associated CD32a (GPI-anchored CD32a) exhibited increased capacity for IgG binding compared with the full-length transmembrane CD32a. Our findings clearly suggest a major role for lipid rafts in the regulation of IgG binding and, more specifically, that suppression of CD32a-mediated IgG binding in myeloid cells is achieved by receptor exclusion from lipid raft membrane microdomains.