bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dendritic Cell Maturation Requires STAT1 and Is under Feedback Regulation by Suppressors of Cytokine Signaling
Authors: Jackson Sharon H. , Yu Cheng-Rong , Mahdi Rashid M. , Ebong Samuel , Egwuagu Charles E. 
Published: April 2014

Abstract
In this study we show that activation of STAT pathways is developmentally regulated and plays a role in dendritic cell (DC) differentiation and maturation. The STAT6 signaling pathway is constitutively activated in immature DC (iDC) and declines as iDCs differentiate into mature DCs (mDCs). However, down-regulation of this pathway during DC differentiation is accompanied by dramatic induction of suppressors of cytokine signaling 1 (SOCS1), SOCS2, SOCS3, and cytokine-induced Src homology 2-containing protein expression, suggesting that inhibition of STAT6 signaling may be required for DC maturation. In contrast, STAT1 signaling is most robust in mDCs and is not inhibited by the up-regulated SOCS proteins, indicating that STAT1 and STAT6 pathways are distinctly regulated in maturing DC. Furthermore, optimal activation of STAT1 during DC maturation requires both IL-4 and GM-CSF, suggesting that synergistic effects of both cytokines may in part provide the requisite STAT1 signaling intensity for DC maturation. Analyses of STAT1−/− DCs reveal a role for STAT1 in repressing CD86 expression in precursor DCs and up-regulating CD40, CD11c, and SOCS1 expression in mDCs. We further show that SOCS proteins are differentially induced by IL-4 and GM-CSF in DCs. SOCS1 is primarily induced by IL-4 through a STAT1-dependent mechanism, whereas SOCS3 is induced mainly by GM-CSF. Taken together, these results suggest that cytokine-induced maturation of DCs is under feedback regulation by SOCS proteins and that the switch from constitutive activation of the STAT6 pathway in iDCs to predominant use of STAT1 signals in mDC is mediated in part by STAT1-induced SOCS expression.
Caspase-3 Is a Component of Fas Death-Inducing Signaling Complex in Lipid Rafts and Its Activity Is Required for Complete Caspase-8 Activation during Fas-Mediated Cell Death
Authors: Aouad Salah M. , Cohen Luchino Y. , Sharif-Askari Ehsan , Haddad Elias K. , Alam Antoine , Sekaly Rafick-Pierre 
Published: April 2014

Abstract
Since its discovery, caspase-8 has been placed at the apex of the proteolytic cascade triggered by death receptor (DR) cross-linking. Because of its capacity to interact with the cytoplasmic portion of DR, it has been suggested that caspase-8 acts independently of other caspases in the initiation of Fas and other DR signaling. In this study, we demonstrate that in Jurkat cells, caspase-3 cleavage is an early step during Fas-induced apoptosis. We show that caspase-3 processing into its p20 occurs rapidly after Fas cross-linking, in the absence of mitochondrial depolarization and caspase-9 activation. Moreover, caspase-3 is present in lipid rafts of untreated Jurkat cells and peripheral T lymphocytes. Caspase-3, caspase-8, and Fas-associated death domain are further recruited to lipid rafts of Jurkat cells following anti-Fas treatment. Fas immunoprecipitation reveals that caspase-3 is a component of the death-inducing signaling complex, suggesting that this cysteine protease is in close proximity to caspase-8. Furthermore, transduction of Jurkat cells with a caspase-3 dominant-negative form inhibits caspase-8 processing and results in inhibition of apoptosis, suggesting that caspase-3 activity is required for caspase-8 activation. Overall, these findings support a model whereby caspase-3 is a component of the death-inducing signaling complex located in lipid rafts, and as such, is involved in the amplification of caspase-8 activity by the mitochondrion.
Activation of Discoidin Domain Receptor 1 Isoform b with Collagen Up-Regulates Chemokine Production in Human Macrophages: Role of p38 Mitogen-Activated Protein Kinase and NF-κB
Authors: Matsuyama Wataru , Wang Lihua , Farrar William L. , Faure Michel , Yoshimura Teizo 
Published: April 2014

Abstract
Macrophages produce an array of proinflammatory mediators at sites of inflammation and contribute to the development of inflammatory responses. Important roles for cytokines, such as IL-1 or TNF-α, and bacterial products, such as LPS, in this process have been well documented; however, the role for the extracellular matrix proteins, such as collagen, remains unclear. We previously reported that discoidin domain receptor 1 (DDR1), a nonintegrin collagen receptor, is expressed during differentiation of human monocytes into macrophages, and the interaction of the DDR1b isoform with collagen facilitates their differentiation via the p38 mitogen-activated protein kinase (MAPK) pathway. In this study, we report that the interaction of DDR1b with collagen up-regulates the production of IL-8, macrophage inflammatory protein-1α, and monocyte chemoattractant protein-1 in human macrophages in a p38 MAPK- and NF-κB-dependent manner. p38 MAPK was critical for DDR1b-mediated, increased NF-κB trans-activity, but not for IκB degradation or NF-κB nuclear translocation, suggesting a role for p38 MAPK in the modification of NF-κB. DDR1b-mediated IκB degradation was mediated through the recruitment of the adaptor protein Shc to the LXNPXY motif of the receptor and the downstream TNFR-associated factor 6/NF-κB activator 1 signaling cascade. Taken together, our study has identified NF-κB as a novel target of DDR1b signaling and provided a novel mechanism by which tissue-infiltrating macrophages produce large amounts of chemokines during the development of inflammatory diseases. Intervention of DDR1b signaling may be useful to control inflammatory diseases in which these proteins play an important role.
FcεRIγ-ITAM Is Differentially Required for Mast Cell Function In Vivo
Authors: Sakurai Daiju , Yamasaki Sho , Arase Kanako , Park Seung Yong , Arase Hisashi , Konno Akiyoshi , Saito Takashi 
Published: April 2014

Abstract
The cross-linking of IgE-bound FcεRI by Ags triggers mast cell activation leading to allergic reactions. The in vivo contribution of FcεRIγ signaling to IgE/FcεRI-mediated mast cell responses has not yet been elucidated. In this study FcεRIγ−/− mast cells were reconstituted with either wild-type or mutant FcεRIγ in transgenic mice and transfected mast cells in vitro. We demonstrate that FcεRIγ-immunoreceptor tyrosine-based activation motif is essential for degranulation, cytokine production, and PG synthesis as well as for passive systemic anaphylaxis. Recent reports have suggested that cell surface FcεRI expression and mast cell survival are regulated by IgE in the absence of Ag, although the molecular mechanism is largely unknown. We also found that the promotion of mast cell survival by IgE without Ags is mediated by signals through the FcεRIγ-immunoreceptor tyrosine-based activation motif. In contrast, the IgE-mediated up-regulation of FcεRI is independent of FcεRIγ signaling. These results indicate that FcεRIγ-mediated signals differentially regulate the receptor expression, activation, and survival of mast cells and systemic anaphylaxis.
Activation/Division of Lymphocytes Results in Increased Levels of Cytoplasmic Activation/Proliferation-Associated Protein-1: Prototype of a New Family of Proteins
Authors: Grill Brock , Wilson Gary M. , Zhang Kai-Xin , Wang Bin , Doyonnas Regis , Quadroni Manfredo , Schrader John W. 
Published: April 2014

Abstract
We purified from activated T lymphocytes a novel, highly conserved, 116-kDa, intracellular protein that occurred at high levels in the large, dividing cells of the thymus, was up-regulated when resting T or B lymphocytes or hemopoietic progenitors were activated, and was down-regulated when a monocytic leukemia, M1, was induced to differentiate. Expression of the protein was highest in the thymus and spleen and lowest in tissues with a low proportion of dividing cells such as kidney or muscle, although expression was high in the brain. The protein was localized to the cytosol and was phosphorylated, which is consistent with a previous report that the Xenopus laevis ortholog was phosphorylated by a mitotically activated kinase (1 ). The cDNA was previously mischaracterized as encoding p137, a 137-kDa GPI-linked membrane protein (2 ). We propose that the authentic protein encoded by this cDNA be called cytoplasmic activation/proliferation-associated protein-1 (caprin-1), and show that it is the prototype of a novel family of proteins characterized by two novel protein domains, termed homology regions-1 and -2 (HR-1, HR-2). Although we have found evidence for caprins only in urochordates and vertebrates, two insect proteins exhibit well-conserved HR-1 domains. The HR-1 and HR-2 domains have no known function, although the HR-1 of caprin-1 appeared necessary for formation of multimeric complexes of caprin-1. Overexpression of a fusion protein of enhanced green fluorescent protein and caprin-1 induced a specific, dose-dependent suppression of the proliferation of NIH-3T3 cells, consistent with the notion that caprin-1 plays a role in cellular activation or proliferation.
Antibody-Dependent Cellular Cytotoxicity via Humoral Immune Epitope of Nef Protein Expressed on Cell Surface
Authors: Yamada Takeshi , Watanabe Nobukazu , Nakamura Tetsuya , Iwamoto Aikichi 
Published: April 2014

AbstractAntibodies against various proteins of HIV type 1 (HIV-1) can be detected in HIV-1-infected individuals. We previously reported that the level of Ab response against one Nef epitope is correlated with HIV-1 disease progression. To elucidate the mechanism for this correlation, we examined Ab-dependent cellular cytotoxicity (ADCC) against target cells expressing Nef. We observed efficient cytotoxicity against Nef-expressing target cells in the presence of patient plasma and PBMCs. This ADCC activity was correlated with the dilution of plasma from HIV-1-infected patients. Addition of a specific synthetic peptide (peptide 31:FLKEKGGLE) corresponding to the Nef epitope reduced cell lysis to ∼50%. These results suggest that PBMCs of HIV-1-infected patients may exert ADCC via anti-Nef Abs in the patients’ own plasma and serve as a mechanism used by the immune system to regulate HIV-1 replication.
Calcium and Its Role in the Nuclear Translocation and Activation of Cytosolic Phospholipase A2 in Cells Rendered Sensitive to TNF-Induced Apoptosis by Cycloheximide
Authors: Draper David W. , Harris Virginia G. , Culver Carolyn A. , Laster Scott M. 
Published: April 2014

Abstract
In these experiments, we investigated the role of calcium as a second messenger in the apoptotic activation of cytosolic phospholipase A2 (cPLA2). As our model, we used a murine fibroblast cell line (C3HA) that was induced to undergo apoptosis by a combination of TNF and cycloheximide. Using fura 2 Ca2+ imaging, we found strong evidence for an intracellular calcium response after 1 h of treatment, which correlated with the onset of phosphatidylserine externalization, but preceded effector procaspase processing by several hours. The response was strongest in the perinuclear region, where mean levels rose 83% (144 ± 14 nM in untreated cells vs 264 ± 39 nM in treated), while cells displaying morphological evidence of apoptosis had the highest levels of calcium (250–1000 nM). Verapamil blocked this response, indicating an extracellular source for the calcium. Fluorescence microscopy revealed a pattern of nuclear translocation of cPLA2 during apoptosis, which was also blocked by verapamil, indicating an important role for calcium in this process. In addition, we found that verapamil prevented the release of [3H]arachidonic acid from C3HA cells induced to undergo apoptosis by the chemotherapeutic agents vinblastine, melphalan, and cis-platinum. Together, these data suggest that calcium is important for cPLA2 activation by diverse apoptotic stimuli.
Peripheral CD4 T Cells Rapidly Accumulate at the Host:Parasite Interface during an Inflammatory Th2 Memory Response
Authors: Morimoto Motoko , Morimoto Masahiro , Whitmire Jeannette , Xiao Shiyun , Anthony Robert M. , Mirakami Hiroshi , Star Robert A. , Urban Joseph F. , Gause William C. 
Published: April 2014

Abstract
Memory peripheral Th2 immune responses to infectious pathogens are not well studied due to the lack of suitable models and the difficulty of assessing Th2 cytokine expression at sites of inflammation. We have examined the localized immune response to a nematode parasite that encysts in the small intestine. An unexpected architecture was observed on day 4 of the memory response, with granulocytes and macrophages infiltrating the cyst and CD4+, TCR-αβ+ T cells surrounding the cyst. Laser capture microdissection analysis showed a pronounced CD4-dependent Th2 cytokine pattern at the cyst region only during the memory response, demonstrating that the Th2 memory response is readily distinguished from the primary response by the rapid accumulation of Th2 effector cells at the host:parasite interface.
Haemophilus influenzae Type b-Outer Membrane Protein Complex Glycoconjugate Vaccine Induces Cytokine Production by Engaging Human Toll-Like Receptor 2 (TLR2) and Requires the Presence of TLR2 for Optimal Immunogenicity
Authors: Latz Eicke , Franko Jennifer , Golenbock Douglas T. , Schreiber John R. 
Published: April 2014

Abstract
Conjugate vaccines consisting of the capsular polysaccharide (PS) of Haemophilus influenzae type b (Hib) covalently linked to carrier proteins, unlike pure PS, are immunogenic in infants and have significantly reduced Hib infections in the United States, but require multiple doses to induce protective anti-PS Ab titers. Hib-meningococcal outer membrane protein complex (OMPC) conjugate vaccine, however, elicits protective anti-PS Ab titers after one dose. We found that OMPC and Hib-OMPC engaged human Toll-like receptor 2 (TLR2) expressed in human embryonic kidney (HEK) cells, inducing IL-8 production, and engaged mouse TLR2 on bone marrow-derived dendritic cells, inducing TNF release. Hib conjugated to the carrier proteins CRM197 and tetanus toxoid did not engage TLR2 on HEK or dendritic cells. Engagement of TLR2 by Hib-OMPC was MyD88 dependent, as Hib-OMPC-induced TNF production was ablated in MyD88 knockout (KO) mice. Hib-OMPC was significantly less immunogenic in TLR2 KO mice, inducing lower Hib PS IgG and IgM titers compared with those in wild-type mice. Splenocytes from OMPC-immunized TLR2 KO mice also produced significantly less IL-6 and TNF-α than those from wild-type mice. Hib-OMPC is unique among glycoconjugate vaccines by engaging TLR2, and the ability of Hib-OMPC to elicit protective levels of Abs after one dose may be related to TLR2-mediated induction and regulation of cytokines produced by T cells and macrophages in addition to the peptide/MHC II-dependent recruitment of T cell help commonly afforded by carrier proteins. TLR2 engagement by an adjuvant or carrier protein may be a useful strategy for augmentation of the anti-PS Ab response induced by glycoconjugate vaccines.
Parasite Antigen-Driven Basophils Are a Major Source of IL-4 in Human Filarial Infections
Authors: Mitre Edward , Taylor Rebekah T. , Kubofcik Joseph , Nutman Thomas B. 
Published: April 2014

AbstractBasophil contribution to the IL-4 pool in filarial infections was assessed using PBMC from 20 patients with active filarial infections and from 9 uninfected subjects. Patient basophils released histamine in response to Brugia malayi Ag (BmAg). They also released IL-4 within 2 h after exposure to BmAg, as assessed by intracellular cytokine flow cytometry. This IL-4 induction was Ag specific, as IL-4 was not detected in BmAg-exposed basophils obtained from uninfected subjects. Although there were, on average, 64 times more CD4+ T cells than basophils in the peripheral circulation of filaria-infected patients, the absolute numbers of basophils and CD4+ T cells producing IL-4 per 100,000 PBMC were equivalent (geometric mean: 16 IL-4-producing basophils/100,000 PBMC vs 22 IL-4-producing CD4+ T cells/100,000 PBMC). Basophils also released IL-4 in response to both low and high concentrations of BmAg, whereas CD4+ T cells released IL-4 only after incubation with a high concentration of BmAg, raising the possibility that basophils, due to their lower threshold for activation, may actually release IL-4 more frequently than CD4+ T cells in vivo. Furthermore, IL-4 production in vitro by Ag-stimulated purified basophils or CD4+ T cells provided evidence that basophils release greater quantities of IL-4 per cell than CD4+ T cells in response to BmAg. These results suggest that, when Ag-specific IgE is present in a filaria-infected individual, basophils function to amplify the ongoing Th2 response by releasing IL-4 in greater amounts and possibly more frequently than CD4+ T cells in response to filarial Ag.
The Zinc Finger Mutation C417R of I-κB Kinase γ Impairs Lipopolysaccharide- and TNF-Mediated NF-κB Activation through Inhibiting Phosphorylation of the I-κB Kinase β Activation Loop
Authors: Yang Fan , Yamashita Junro , Tang Eric , Wang Hom-lay , Guan Kunliang , Wang Cun-Yu 
Published: April 2014

Abstract
The activation of the I-κB kinase (IKK) complex by TNF or LPS stimulates phosphorylation and degradation of I-κBα, leading to the nuclear translocation of NF-κB. The IKK complex is mainly composed of two catalytic subunits, IKKα and IKKβ, and a chaperon subunit IKKγ. Although IKKγ does not have catalytic activity, it is essential for IKK activation induced by multiple stimuli. Importantly, the key residue cysteine 417 at the zinc finger domain of IKKγ has been found to be mutated to arginine (IKKγC417R) in a human genetic disorder called the anhydrotic ectodermal dysplasia with immunodeficiency. To understand the underlying mechanisms of immunodeficiency, we examined whether the IKKγC417R mutant modified IKK activation and NF-κB transcription stimulated by LPS or TNF in human monocytes. We found that overexpression of IKKγC417R severely impaired LPS- and TNF-induced I-κBα phosphorylation and degradation in a dominant-negative fashion. Also, LPS- and TNF-induced NF-κB transcription was inhibited by IKKγC417R. The reconstitution of IKKγ, but not IKKγC417R, in IKKγ-deficient cells restored NF-κB signaling, indicating the zinc finger structure of IKKγ plays a key role in IKK activation. Moreover, C417R mutation in IKKγ abolished both LPS- and TNF-induced phosphorylation of the activation loop of IKKβ. Collectively, our results indicated that the zinc finger structure of IKKγ plays a key role in LPS- and TNF-induced NF-κB activation. The anhydrotic ectodermal dysplasia with immunodeficiency patients’ immunodeficiency may be associated with NF-κB defect in response to bacterial stimulation.
Protective T Cell Immunity against Malaria Liver Stage after Vaccination with Live Sporozoites under Chloroquine Treatment
Authors: Belnoue Elodie , Costa Fabio T. M. , Frankenberg Tobias , Vigário Ana Margarida , Voza Tatiana , Leroy Nicolas , Rodrigues Mauricio M. , Landau Irène , Snounou Georges , Rénia Laurent 
Published: April 2014

Abstract
In this study we present the first systematic analysis of the immunity induced by normal Plasmodium yoelii sporozoites in mice. Immunization with sporozoites, which was conducted under chloroquine treatment to minimize the influence of blood stage parasites, induced a strong protection against a subsequent sporozoite and, to a lesser extent, against infected RBC challenges. The protection induced by this immunization protocol proved to be very effective. Induction of this protective immunity depended on the presence of liver stage parasites, as primaquine treatment concurrent with sporozoite immunization abrogated protection. Protection was not found to be mediated by the Abs elicited against pre-erythrocytic and blood stage parasites, as demonstrated by inhibition assays of sporozoite penetration or development in vitro and in vivo assays of sporozoite infectivity or blood stage parasite development. CD4+ and CD8+ T cells were, however, responsible for the protection through the induction of IFN-γ and NO.
TNF Receptor Signaling Contributes to Chemokine Secretion, Inflammation, and Respiratory Deficits duringPneumocystisPneumonia
Authors: Wright Terry W. , Pryhuber Gloria S. , Chess Patricia R. , Wang Zhengdong , Notter Robert H. , Gigliotti Francis 
Published: April 2014

AbstractCD8+ T cells contribute to the pathophysiology of Pneumocystis pneumonia (PcP) in a murine model of AIDS-related disease. The present studies were undertaken to more precisely define the mechanisms by which these immune cells mediate the inflammatory response that leads to lung injury. Experimental mice were depleted of either CD4+ T cells or both CD4+ and CD8+ T cells and then infected with Pneumocystis. The CD4+-depleted mice had significantly greater pulmonary TNF-α levels than mice depleted of both CD4+ and CD8+ T cells. Elevated TNF-α levels were associated with increased lung concentrations of the chemokines RANTES, monocyte chemoattractant protein 1, macrophage-inflammatory protein 2, and cytokine-induced neutrophil chemoattractant. To determine whether TNFR signaling was involved in the CD8+ T cell-dependent chemokine response, TNFRI- and II-deficient mice were CD4+ depleted and infected with Pneumocystis. TNFR-deficient mice had significantly reduced pulmonary RANTES, monocyte chemoattractant protein 1, macrophage-inflammatory protein 2, and cytokine-induced neutrophil chemoattractant responses, reduced inflammatory cell recruitment to the alveoli, and reduced histological evidence of PcP-related alveolitis as compared with infected wild-type mice. Diminished pulmonary inflammation correlated with improved surfactant activity and improved pulmonary function in the TNFR-deficient mice. These data indicate that TNFR signaling is required for maximal CD8+ T cell-dependent pulmonary inflammation and lung injury during PcP and also demonstrate that CD8+ T cells can use TNFR signaling pathways to respond to an extracellular fungal pathogen.
Involvement of Reactive Oxygen Species in Toll-Like Receptor 4-Dependent Activation of NF-κB
Authors: Asehnoune Karim , Strassheim Derek , Mitra Sanchayita , Kim Jae Yeol , Abraham Edward 
Published: April 2014

Abstract
Although oxidative stress has been thought to play a general role in the activation of NF-κB, the involvement of reactive oxygen species (ROS) in facilitating nuclear translocation of NF-κB in neutrophils has not been described. In addition, the mechanisms by which ROS modulate the transcriptional activity of NF-κB in response to Toll-like receptor 4 (TLR4)-dependent signaling are not well characterized. To examine these issues, oxidant-dependent signaling events downstream of TLR4 were investigated in neutrophils stimulated with LPS. Pretreatment of neutrophils with the antioxidants N-acetylcysteine or α-tocopherol prevented LPS-induced nuclear translocation of NF-κB. Antioxidant treatment of LPS-stimulated neutrophils also inhibited the production of proinflammatory cytokines (TNF-α, macrophage inflammatory protein-2, and IL-1β), as well as activation of the kinases IκB kinase α, IκB kinase β, p38, Akt, and extracellular receptor-activated kinases 1 and 2. The decrease in cytoplasmic levels of IκBα produced by exposure of neutrophils to LPS was prevented by N-acetylcysteine or α-tocopherol. Activation of IL-1R-associated kinase-1 (IRAK-1) and IRAK-4 in response to LPS stimulation was inhibited by antioxidants. These results demonstrate that proximal events in TLR4 signaling, at or antecedent to IRAK-1 and IRAK-4 activation, are oxidant dependent and indicate that ROS can modulate NF-κB-dependent transcription through their involvement in early TLR4-mediated cellular responses.