bluuebunny/crossref_metadata_2025_split huggingface dataset:
Surfactant Protein A Regulates Complement Activation
Authors: Watford Wendy T. , Wright Jo Rae , Hester C. Garren , Jiang Haixiang , Frank Michael M. 
Published: April 2014

AbstractComplement proteins aid in the recognition and clearance of pathogens from the body. C1, the first protein of the classical pathway of complement activation, is a calcium-dependent complex of one molecule of C1q and two molecules each of C1r and C1s, the serine proteases that cleave complement proteins. Upon binding of C1q to Ag-bound IgG or IgM, C1r and C1s are sequentially activated and initiate the classical pathway of complement. Because of structural and functional similarities between C1q and members of the collectin family of proteins, including pulmonary surfactant protein A (SP-A), we hypothesized that SP-A may interact with and regulate proteins of the complement system. Previously, SP-A was shown to bind to C1q, but the functional significance of this interaction has not been investigated. Binding studies confirmed that SP-A binds directly to C1q, but only weakly to intact C1. Further investigation revealed that the binding of SP-A to C1q prevents the association of C1q with C1r and C1s, and therefore the formation of the active C1 complex required for classical pathway activation. This finding suggests that SP-A may share a common binding site for C1r and C1s or Clq. SP-A also prevented C1q and C1 from binding to immune complexes. Furthermore, SP-A blocked the ability of C1q to restore classical pathway activity to C1q-depleted serum. SP-A may down-regulate complement activity through its association with C1q. We hypothesize that SP-A may serve a protective role in the lung by preventing C1q-mediated complement activation and inflammation along the delicate alveolar epithelium.
IFN-γ Affects Homing of Diabetogenic T Cells
Authors: Savinov Alexei Y. , Wong F. Susan , Chervonsky Alexander V. 
Published: April 2014

AbstractIFN-γ is a cytokine with pleiotropic functions that participates in immune and autoimmune responses. The lack of IFN-γ is known to delay the development of autoimmune diabetes in nonobese diabetic (NOD) mice. Splenocytes from diabetic NOD and IFN-γ knockout (KO) NOD mice transfer diabetes into NOD recipients equally well. However, adoptive transfer of diabetogenic T cells from NOD mice into NOD.IFN-γ-KO or NOD mice lacking β-chain of IFN-γ receptor (NOD.IFN-γRβ-KO) appeared to be much less efficient. We found that IFN-γ influences the ability of diabetogenic cells to penetrate pancreatic islets. Tracing in vivo of insulin-specific CD8+ T cells has shown that homing of these cells to the islets of Langerhans was affected by the lack of IFN-γ. While adhesion of insulin-specific CD8+ cells to microvasculature was normal, the diapedesis was significantly impaired. This effect was reversible by treatment of the animals with rIFN-γ. Thus, IFN-γ may, among other effects, influence immune and autoimmune responses by supporting the homing of activated T cells.
Expression and Regulation of Fas and Fas Ligand on Thyrocytes and Infiltrating Cells During Induction and Resolution of Granulomatous Experimental Autoimmune Thyroiditis
Authors: Wei Yongzhong , Chen Kemin , Sharp Gordon C. , Yagita Hideo , Braley-Mullen Helen 
Published: April 2014

Abstract
Granulomatous experimental autoimmune thyroiditis (G-EAT) is induced by mouse thyroglobulin-sensitized spleen cells activated in vitro with mouse thyroglobulin, anti-IL-2R, and IL-12. G-EAT lesions reach maximal severity 19–21 days after cell transfer, and lesions almost completely resolve by day 35. Depletion of CD8+ cells delays resolution and reduces Fas ligand (FasL) mRNA expression in thyroids. This study was undertaken to analyze Fas and FasL protein expression in the thyroid during induction and resolution of G-EAT and to determine whether CD8+ cells might regulate Fas or FasL expression in the thyroid. Fas and FasL expression was analyzed by immunohistochemical staining or in situ hybridization in thyroids of mice with or without depletion of CD8+ cells. Fas and FasL proteins were not detectable in normal thyroids, but expression of both proteins increased during development of G-EAT. Fas was expressed primarily by inflammatory cells; some enlarged thyrocytes were also Fas+. Thyrocytes had intense FasL immunoreactvity, and many CD8+ cells were also FasL positive. Depletion of CD8+ cells resulted in decreased FasL expression by thyrocytes and inflammatory cells, but had no effect on Fas expression. TUNEL assay detected many apoptotic inflammatory cells in proximity to thyrocytes. CD8-depleted thyroids had ongoing inflammation with fewer apoptotic infiltrating cells at day 35. Administration of a neutralizing anti-FasL mAb had no apparent effects on development of G-EAT, but anti-FasL was as effective as anti-CD8 in preventing G-EAT resolution. These results suggested that CD8+ T cells and thyrocytes may kill inflammatory cells through the Fas pathway, contributing to G-EAT resolution.
Differential Secretion of Fas Ligand- or APO2 Ligand/TNF-Related Apoptosis-Inducing Ligand-Carrying Microvesicles During Activation-Induced Death of Human T Cells
Authors: Monleón Inmaculada , Martínez-Lorenzo María José , Monteagudo Luis , Lasierra Pilar , Taulés Marta , Iturralde María , Piñeiro Andrés , Larrad Luis , Alava María Angeles , Naval Javier , Anel Alberto 
Published: April 2014

AbstractPreformed Fas ligand (FasL) and APO2 ligand (APO2L)/TNF-related apoptosis-inducing ligand (TRAIL) are stored in the cytoplasm of the human Jurkat T cell line and of normal human T cell blasts. The rapid release of these molecules in their bioactive form is involved in activation-induced cell death. In this study, we show by confocal microscopy that FasL and APO2L/TRAIL are mainly localized in lysosomal-like compartments in these cells. We show also by immunoelectron microscopy that FasL and APO2L/TRAIL are stored inside cytoplasmic compartments ∼500 nm in diameter, with characteristics of multivesicular bodies. Most of these compartments share FasL and APO2L/TRAIL, although exclusive APO2L/TRAIL labeling can be also observed in separate compartments. Upon PHA activation, the mobilization of these compartments toward the plasma membrane is evident, resulting in the secretion of the internal microvesicles loaded with FasL and APO2L/TRAIL. In the case of activation with anti-CD59 mAb, the secretion of microvesicles labeled preferentially with APO2L/TRAIL predominates. These data provide the basis of a new and efficient mechanism for the rapid induction of autocrine or paracrine cell death during immune regulation and could modify the interpretation of the role of FasL and APO2L/TRAIL as effector mechanisms in physiological and pathological situations.
Regulation and Possible Function of β-Catenin in Human Monocytes
Authors: Thiele Andrea , Wasner Mark , Müller Claudia , Engeland Kurt , Hauschildt Sunna 
Published: April 2014

AbstractIn this study, we demonstrate that adherence factors, serum constituents, LPS, and zymosan are capable of inducing a cellular accumulation of β-catenin in human monocytes. Whereas adherence-dependent accumulation of β-catenin can be blocked by wortmannin, an inhibitor of phosphatidylinositol 3-kinase, accumulation induced by the remaining stimuli cannot be prevented by inhibition of phosphatidylinositol 3-kinase, implying the involvement of β-catenin in other not yet described signal transduction pathways. A role of β-catenin in adherence-dependent processes by interacting with classical cadherins can be excluded as we could not detect cadherins in monocytes. To test whether it is possible that β-catenin interacts with LEF/TCF (lymphoid enhancer factor/T cell factor) transcription factors, we studied the expression of this protein family. TCF-4 was identified as the LEF/TCF transcription factor present in human monocytes. However, neither cellular induction of β-catenin nor cotransfection experiments with β-catenin conducted in the monocytic cell line THP-1 resulted in the activation of a LEF/TCF-dependent promoter, suggesting the requirement of additional signals. Concurrent with this suggestion, we found that LPS and zymosan, two physiological inducers of β-catenin, caused an increase in the expression of genes that are positively regulated by β-catenin.
TNF Type 2 Receptor (p75) Lowers the Threshold of T Cell Activation
Authors: Kim Edward Y. , Teh Hung-Sia 
Published: April 2014

AbstractT cell activation requires a threshold amount of TCR-mediated signals, an amount that is reduced by signals mediated through costimulatory molecules expressed on the T cell surface. Here the role of TNFR2 (p75) as a putative costimulatory receptor for T cell activation was examined. It was found that p75 deficiency in CD8+ T cells increased the requirements for TCR agonist approximately 5-fold. Furthermore, p75−/− T cells display a marked reduction in the proliferative response to TCR agonist. This hypoproliferative response was associated with delayed kinetics of induction of the acute activation markers CD25 and CD69 as well as a marked decrease in the production of IL-2 and IFN-γ. The net result is that very few cells are recruited into the dividing population. Interestingly, CD28 costimulation was only partially effective in rescuing the proliferative defect of p75−/−CD8+ T cells. Thus, p75 provides an important costimulatory signal in addition to that provided by CD28 toward optimal T cell proliferation.
Immunoproteasomes Largely Replace Constitutive Proteasomes During an Antiviral and Antibacterial Immune Response in the Liver
Authors: Khan Selina , van den Broek Maries , Schwarz Katrin , de Giuli Rita , Diener Pierre-André , Groettrup Marcus 
Published: April 2014

AbstractThe proteasome is critically involved in the production of MHC class I-restricted T cell epitopes. Proteasome activity and epitope production are altered by IFN-γ treatment, which leads to a gradual replacement of constitutive proteasomes by immunoproteasomes in vitro. However, a quantitative analysis of changes in the steady state subunit composition of proteasomes during an immune response against viruses or bacteria in vivo has not been reported. Here we show that the infection of mice with lymphocytic choriomeningitis virus or Listeria monocytogenes leads to an almost complete replacement of constitutive proteasomes by immunoproteasomes in the liver within 7 days. Proteasome replacements were markedly reduced in IFN-γ−/− mice, but were only slightly affected in IFN-αR−/− and perforin−/− mice. The proteasome regulator PA28α/β was up-regulated, whereas PA28γ was reduced in the liver of lymphocytic choriomeningitis virus-infected mice. Proteasome replacements in the liver strongly altered proteasome activity and were unexpected to this extent, since an in vivo half-life of 12 days had been previously assigned to constitutive proteasomes in the liver. Our results suggest that during the peak phase of viral and bacterial elimination the antiviral cytotoxic T lymphocyte response is directed mainly to immunoproteasome-dependent T cell epitopes, which would be a novel parameter for the design of vaccines.
Differential IL-10R1 Expression Plays a Critical Role in IL-10-Mediated Immune Regulation
Authors: Ding Yaozhong , Qin Lihui , Zamarin Dmitriy , Kotenko Sergei V. , Pestka Sidney , Moore Kevin W. , Bromberg Jonathan S. 
Published: April 2014

AbstractIn this study, we characterized the differential receptor-binding specificity, affinity, and Janus kinase-STAT activation of cellular IL-10 (cIL-10) compared with viral IL-10 (vIL-10). Only cells expressing IL-10R1 bind human IL-10 or vIL-10. IL-10R2 does not bind to cIL-10 or vIL-10 alone and its presence does not enhance the receptor-binding affinity of cIL-10 or vIL-10, but it is essential for both cIL-10- and vIL-10-mediated signal transduction and immune regulation. Responses initiated by cIL-10 and vIL-10 were compared in B cell and mast cell lines, and demonstrated that the inability of vIL-10 to stimulate immune responses, as compared with human IL-10, is due to failure to initiate signaling. Absent signal transduction is due to low level expression of cell surface IL-10R1, since overexpressing IL-10R1 allows vIL-10 to initiate cIL-10-like signals and subsequent biological responses. These results are similar in primary cells, since splenocytes respond to both cIL-10 and vIL-10, while thymocytes respond only to cIL-10 and have very low mouse IL-10R1 but not mouse IL-10R2 expression. These data demonstrate that IL-10R1 expression plays a critical role in determining whether cells respond to IL-10. Modulation of cell surface IL-10R1 density might be an important mechanism for determining whether IL-10 leads to immunostimulation or immunosuppression in vivo.
Enteric Bacteria Counteract Lipopolysaccharide Induction of Antimicrobial Peptide Genes
Authors: Lindmark Hans , Johansson Karin C. , Stöven Svenja , Hultmark Dan , Engström Ylva , Söderhäll Kenneth 
Published: April 2014

Abstract
The humoral immunity of Drosophila involves the production of antimicrobial peptides, which are induced by evolutionary conserved microbial molecules, like LPS. By using Drosophila mbn-2 cells, we found that live bacteria, including E. coli, Salmonella typhimurium, Erwinia carotovora, and Pseudomonas aeruginosa, prevented LPS from inducing antimicrobial peptide genes, while Micrococcus luteus and Streptococcus equi did not. The inhibitory effect was seen at bacterial levels from 20 per mbn-2 cell, while antimicrobial peptides were induced at lower bacterial concentrations (≤2 bacteria per cell) also in the absence of added LPS. Gel shift experiment suggests that the inhibitory effect is upstream or at the level of the activation of the transcription factor Relish, a member of the NF-κB/Rel family. The bacteria have to be in physical contact with the cells, but not phagocytosed, to prevent LPS induction. Interestingly, the inhibiting mechanism is, at least for E. coli, independent of the type III secretion system, indicating that the inhibitory mechanism is unrelated to the one earlier described for YopJ from Yersinia.
Hydrogen Bond Integrity Between MHC Class II Molecules and Bound Peptide Determines the Intracellular Fate of MHC Class II Molecules
Authors: Arneson Lynne S. , Katz John F. , Liu Michael , Sant Andrea J. 
Published: April 2014

AbstractMHC class II molecules associate with peptides through pocket interactions and the formation of hydrogen bonds. The current paradigm suggests that the interaction of side chains of the peptide with pockets in the class II molecule is responsible for the formation of stable class II-peptide complexes. However, recent evidence has shown that the formation of hydrogen bonds between genetically conserved residues of the class II molecule and the main chain of the peptide contributes profoundly to peptide stability. In this study, we have used I-Ak, a class II molecule known to form strong pocket interactions with bound peptides, to probe the general importance of hydrogen bond integrity in peptide acquisition. Our studies have revealed that abolishing hydrogen bonds contributed by positions 81 or 82 in the β-chain of I-Ak results in class II molecules that are internally degraded when trafficked through proteolytic endosomal compartments. The presence of high-affinity peptides derived from either endogenous or exogenous sources protects the hydrogen bond-deficient variant from intracellular degradation. Together, these data indicate that disruption of the potential to form a complete hydrogen bond network between MHC class II molecules and bound peptides greatly diminishes the ability of class II molecules to bind peptides. The subsequent failure to stably acquire peptides leads to protease sensitivity of empty class II molecules, and thus to proteolytic degradation before export to the surface of APCs.
Control of Advanced Choroid Plexus Tumors in SV40 T Antigen Transgenic Mice Following Priming of Donor CD8+ T Lymphocytes by the Endogenous Tumor Antigen
Authors: Schell Todd D. , Tevethia Satvir S. 
Published: April 2014

AbstractMouse models in which tumors arise spontaneously due to the transgenic expression of an oncoprotein provide an opportunity to test approaches that target the immune-mediated control of tumor progression. In this report we investigated the role of SV40 Tag-specific CD8+ T cells in the control of advanced choroid plexus tumor progression using large tumor Ag (Tag) transgenic mice. Since mice of the SV11 line are tolerant to the immunodominant SV40 Tag-derived CTL epitopes, mice with advanced stage tumors were reconstituted with naive C57BL/6 spleen cells following a low dose of γ-irradiation. This led to the priming of CTLs specific for the H2-Kb-restricted epitope IV by the endogenous Tag and a significant increase in the life span of Tag transgenic mice. Epitope IV-specific CD8+ T cells accumulated and persisted in the brains and tumors of SV11 mice, as determined by analysis with epitope-specific MHC class I tetramers. Brain-infiltrating epitope IV-specific T cells were capable of producing IFN-γ as well as lysing syngeneic Tag-transformed cells in vitro. In addition, the adoptive transfer of spleen cells from Tag-immune C57BL/6 mice resulted in a dramatic increase in the control of tumor progression in SV11 mice and was associated with the accumulation of CD8+ T cells specific for multiple Tag epitopes in the brain. These results indicate that the control of advanced stage spontaneous choroid plexus tumors is associated with the induction of a strong and persistent CD8+ T cell response to Tag.
Bacterial Peptidoglycan-Inducedtnf-αTranscription Is Mediated Through the Transcription Factors Egr-1, Elk-1, and NF-κB
Authors: Xu Zhaojun , Dziarski Roman , Wang Qiuling , Swartz Kevin , Sakamoto Kathleen M. , Gupta Dipika 
Published: April 2014

AbstractBacteria and their ubiquitous cell wall component peptidoglycan (PGN) activate the innate immune system of the host and induce the release of inflammatory molecules. TNF-α is one of the highest induced cytokines in macrophages stimulated with PGN; however, the regulation of tnf-α expression in PGN-activated cells is poorly understood. This study was done to identify some of the transcription factors that regulate the expression of the tnf-α gene in macrophages stimulated with PGN. Our results demonstrated that PGN-induced expression of human tnf-α gene is regulated by sequences proximal to −182 bp of the promoter. Mutations within the binding sites for cAMP response element, early growth response (Egr)-1, and κB3 significantly reduced this induction. The transcription factor c-Jun bound the cAMP response element site, Egr-1 bound the Egr-1 motif, and NF-κB p50 and p65 bound to the κB3 site on the tnf-α promoter. PGN rapidly induced transcription of egr-1 gene and this induction was significantly reduced by specific mutations within the serum response element-1 domain of the egr-1 promoter. PGN also induced phosphorylation and activation of Elk-1, a member of the Ets family of transcription factors. Elk-1 and serum response factor proteins bound the serum response element-1 domain on the egr-1 promoter, and PGN-induced expression of the egr-1 was inhibited by dominant-negative Elk-1. These results indicate that PGN induces activation of the transcription factors Egr-1 and Elk-1, and that PGN-induced expression of tnf-α is directly mediated through the transcription factors c-Jun, Egr-1, and NF-κB, and indirectly through the transcription factor Elk-1.
Salmonella Flagellin-Dependent Proinflammatory Responses Are Localized to the Conserved Amino and Carboxyl Regions of the Protein
Authors: Eaves-Pyles Tonyia D. , Wong Hector R. , Odoms Kelli , Pyles Richard B. 
Published: April 2014

Abstract
Flagellin, the monomeric subunit of flagella, is an inducer of proinflammatory mediators. Bacterial flagellin genes have conserved domains (D1 and D2) at the N terminus and C terminus and a middle hypervariable domain (D3). To identify which domains induced proinflammatory activity, r6-histidine (6HIS)-tagged fusion constructs were generated from the Salmonella dublin (SD) fliC flagellin gene. A full-length r6HIS SD flagellin (6HIS flag) induced IκBα loss poststimulation and NF-κB activation in Caco-2BBe cells and was as potent as native-purified SD flagellin. IFN-γ-primed DLD-1 cells stimulated with 1 μg/ml of 6HIS flag induced high levels of NO (60 ± 0.95 μM) comparable to the combination of IL-1β and IFN-γ (77 ± 1.2) or purified native SD flag (66.3 ± 0.98). Selected rSD flagellin proteins representing the D1, D2, or D3 domains alone or in combination were tested for proinflammatory properties. Fusion proteins representing the D3, amino, or carboxyl regions alone did not induce proinflammatory mediators. The results with a recombinant protein containing the amino D1 and D2 and carboxyl D1 and D2 separated by an Escherichia coli hinge (ND1-2/ECH/CD2) indicated that D1 and D2 were bioactive when coupled to an ECH element to allow protein folding. This chimera, but not the hinge alone, induced IκBα degradation, NF-κB activation, and NO and IL-8 production in two intestinal epithelial cell lines. ND1–2/ECH/CD2–1 also induced high levels of TNF-α (900 pg/ml) in human monocytes comparable to native SD flagellin (991.5 pg/ml) and 6HIS flag (987 pg/ml). The potent proinflammatory activity of flagellin, therefore, resides in the highly conserved N and C D1 and D2 regions.
Regulation of Hepatic Fibrosis and Extracellular Matrix Genes by the Th Response: New Insight into the Role of Tissue Inhibitors of Matrix Metalloproteinases
Authors: Vaillant Brian , Chiaramonte Monica G. , Cheever Allen W. , Soloway Paul D. , Wynn Thomas A. 
Published: April 2014

AbstractHepatic fibrosis is the hallmark of Schistosoma mansoni infection and often results in portal hypertension and bleeding from esophageal varices. The fibrotic process is highly dependent on type 2 cytokines, yet their role in the regulation of extracellular matrix remodeling genes remains largely unknown. Here, we examined the expression of matrix metalloproteases (MMP) -2, -3, -9, -12, and -13 and their inhibitors, tissue inhibitor of metalloproteases (TIMP) -1, -2, and -3, in the livers of infected mice and correlated their expression profiles with fibrosis and type 2 cytokine production. Expression of MMP-2, -3, -9, -12, and -13 and of TIMP-1 and -2 mRNA rapidly increased at the onset of egg laying in infected mice, while TIMP-3 was unchanged. Because TIMP are presumed to be important regulators of the extracellular matrix, and their expression correlated with the development of fibrosis, we studied their role in fibrogenesis by infecting TIMP-1- and TIMP-2-deficient mice. Strikingly, our data revealed no role for TIMP-1 or -2 in the fibrotic pathology induced by S. mansoni eggs. Because of these findings, we infected IL-10/IFN-γ-deficient mice that develop an exaggerated fibrotic response to determine whether changes in type 2 cytokine dominance influence the pattern of MMP and TIMP expression. Fibrosis and type 2 cytokine production correlated with increased MMP-2/MMP-9 vs TIMP-1/TIMP-2 expression. These data, in addition to our knockout studies, demonstrate that TIMP-1/TIMP-2 play no essential role in fibrogenesis in schistosomiasis. Indeed, our findings suggest that inhibiting profibrotic cytokines or specific MMP may be a more effective strategy to ameliorate fibrotic pathology.