bluuebunny/crossref_metadata_2025_split huggingface dataset:
Acute Lung Injury Induced by Lipopolysaccharide Is Independent of Complement Activation
Authors: Rittirsch Daniel , Flierl Michael A. , Day Danielle E. , Nadeau Brian A. , McGuire Stephanie R. , Hoesel Laszlo M. , Ipaktchi Kyros , Zetoune Firas S. , Sarma J. Vidya , Leng Lin , Huber-Lang Markus S. , Neff Thomas A. , Bucala Richard , Ward Peter A. 
Published: April 2014

AbstractAlthough acute lung injury (ALI) is an important problem in humans, its pathogenesis is poorly understood. Airway instillation of bacterial LPS, a known complement activator, represents a frequently used model of ALI. In the present study, pathways in the immunopathogenesis of ALI were evaluated. ALI was induced in wild-type, C3−/−, and C5−/− mice by airway deposition of LPS. To assess the relevant inflammatory mediators, bronchoalveolar lavage fluids were evaluated by ELISA analyses and various neutralizing Abs and receptor antagonists were administered in vivo. LPS-induced ALI was neutrophil-dependent, but it was not associated with generation of C5a in the lung and was independent of C3, C5, or C5a. Instead, LPS injury was associated with robust generation of macrophage migration inhibitory factor (MIF), leukotriene B4 (LTB4), and high mobility group box 1 protein (HMGB1) and required engagement of receptors for both MIF and LTB4. Neutralization of MIF or blockade of the MIF receptor and/or LTB4 receptor resulted in protection from LPS-induced ALI. These findings indicate that the MIF and LTB4 mediator pathways are involved in the immunopathogenesis of LPS-induced experimental ALI. Most strikingly, complement activation does not contribute to the development of ALI in the LPS model.
The Mer Receptor Tyrosine Kinase Is Required for the Loss of B Cell Tolerance in the Chronic Graft-versus-Host Disease Model of Systemic Lupus Erythematosus
Authors: Shao Wen-Hai , Eisenberg Robert A. , Cohen Philip L. 
Published: April 2014

AbstractThe Mer receptor tyrosine kinase mediates apoptotic cell phagocytosis and modulates macrophage cytokine production. Mer−/− mice have defective clearance of apoptotic debris and develop a systemic lupus erythematosus-like autoimmune syndrome. It was surprising then that B6-Mer−/− recipients of bm12 spleen cells failed to develop anti-dsDNA and anti-chromatin autoantibodies, whereas B6 hosts produced the expected autoimmune chronic graft-vs-host (cGVH) reaction. The lack of autoantibody formation in cGVH was not due to the failure of Mer-deficient hosts to provoke alloreactivity, because Mer−/− spleen cells were recognized by bm12 T cells in MLR. Cell transfer experiments in Rag-knockout mice indicated that the lack of autoantibody production in Mer−/− cGVH disease hosts was due to an intrinsic B cell defect. This defect did not cause a global inability to produce autoantibodies, because in vivo exposure to LPS stimulated production of autoantibodies in both B6 and Mer−/− mice. We further observed that wild-type B6 B cells up-regulated Mer upon activation in cGVH, and that B cells from mice lacking Mer showed a decreased up-regulation of activation-associated cell surface markers. These findings indicate that Mer serves an important role in the activation of self-reactive B cells in systemic autoimmunity.
Lysophospholipids and ATP Mutually Suppress Maturation and Release of IL-1β in Mouse Microglial Cells Using a Rho-Dependent Pathway
Authors: Takenouchi Takato , Iwamaru Yoshifumi , Sugama Shuei , Sato Mitsuru , Hashimoto Makoto , Kitani Hiroshi 
Published: April 2014

AbstractThe P2X7 receptor (P2X7R), an ATP-gated ion channel, plays essential roles in the release and maturation of IL-1β in microglial cells in the brain. Previously, we found that lysophosphatidylcholine (LPC) potentiated P2X7R-mediated intracellular signals in microglial cells. In this study, we determined whether the lysophospholipids, i.e., LPC and sphingosylphosphorylcholine (SPC), modulate the ATP-induced release and processing of IL-1β mediated by P2X7R in mouse MG6 microglial cells. LPC or SPC alone induced the release of precursor (pro-IL-1β) and mature IL-1β (mIL-1β) from LPS-primed MG6 cells, possibly due to lytic functions. However, these lysophospholipids inhibited ATP-induced caspase-1 activation that is usually followed by the release of mIL-1β. Conversely, ATP inhibited the release of pro-IL-1β and mIL-1β induced by LPC/SPC. This suggests that lysophospholipids and ATP mutually suppressed each function to release IL-1β. P2X7R activation resulted in microtubule reorganization in the MG6 cells that was blocked in the presence of LPC and SPC. LPC/SPC reduced the amount of activated RhoA after stimulation with ATP, implying that these lysophospholipids block ATP-induced microtubule reorganization by interfering with RhoA activation. In addition, the microtubule inhibitor colchicine inhibited ATP-induced release of mIL-1β similar to that of LPC and SPC. This suggests that the impairment of the microtubule reassembly may be associated with the inhibitory effects of LPC/SPC on ATP-induced mIL-1β release. Mutual suppression by ATP and LPC/SPC on the maturation of IL-1β was observed in LPS-primed primary microglia. Collectively, these data suggest opposing functions by lysophospholipids, either proinflammatory or anti-inflammatory, in regard to the maturation and release of IL-1β from microglial cells.
IFN-γ and STAT1 Arrest Monocyte Migration and Modulate RAC/CDC42 Pathways
Authors: Hu Yang , Hu Xiaoyu , Boumsell Laurence , Ivashkiv Lionel B. 
Published: April 2014

AbstractPositive regulation of cell migration by chemotactic factors and downstream signaling pathways has been extensively investigated. In contrast, little is known about factors and mechanisms that induce migration arrest, a process important for retention of cells at inflammatory sites and homeostatic regulation of cell trafficking. In this study, we found that IFN-γ directly inhibited monocyte migration by suppressing remodeling of the actin cytoskeleton and cell polarization in response to the chemokine CCL2. Inhibition was dependent on STAT1 and downstream genes, whereas STAT3 promoted migration. IFN-γ altered monocyte responses to CCL2 by modulating the activity of Pyk2, JNK, and the GTPases Rac and Cdc42, and inhibiting CCL2-induced activation of the downstream p21-activated kinase that regulates the cytoskeleton and cell polarization. These results identify a new role for IFN-γ in arresting monocyte chemotaxis by a mechanism that involves modulation of cytoskeleton remodeling. Crosstalk between Jak-STAT and Rac/Cdc42 GTPase-mediated signaling pathways provides a molecular mechanism by which cytokines can regulate cell migration.
c-Rel Is Essential for the Development of Innate and T Cell-Induced Colitis
Authors: Wang Yanyan , Rickman Barry H. , Poutahidis Theofilos , Schlieper Katherine , Jackson Erin A. , Erdman Susan E. , Fox James G. , Horwitz Bruce H. 
Published: April 2014

AbstractInflammatory bowel disease is a chronic inflammatory response of the gastrointestinal tract mediated in part by an aberrant response to intestinal microflora. Expression of IL-23 subunits p40 and p19 within cells of the innate immune system plays a central role in the development of lower bowel inflammation in response inflammatory challenge. The NF-κB subunit c-Rel can regulate expression of IL-12/23 subunits suggesting that it could have a critical role in mediating the development of chronic inflammation within the lower bowel. In this study, we have analyzed the role of c-Rel within the innate immune system in the development of lower bowel inflammation, in two well-studied models of murine colitis. We have found that the absence of c-Rel significantly impaired the ability of Helicobacter hepaticus to induce colitis upon infection of RAG-2-deficient mice, and ameliorated the ability of CD4+CD45RBhigh T cells to induce disease upon adoptive transfer into RAG-deficient mice. The absence of c-Rel interfered with the expression of IL-12/23 subunits both in cultured primary macrophages and within the colon. Thus, c-Rel plays a critical role in regulating the innate inflammatory response to microflora within the lower bowel, likely through its ability to modulate expression of IL-12/23 family members.
Tolerization of a Type I Allergic Immune Response through Transplantation of Genetically Modified Hematopoietic Stem Cells
Authors: Baranyi Ulrike , Linhart Birgit , Pilat Nina , Gattringer Martina , Bagley Jessamyn , Muehlbacher Ferdinand , Iacomini John , Valenta Rudolf , Wekerle Thomas 
Published: April 2014

AbstractAllergy represents a hypersensitivity disease that affects &gt;25% of the population in industrialized countries. The underlying type I allergic immune reaction occurs in predisposed atopic individuals in response to otherwise harmless Ags (i.e., allergens) and is characterized by the production of allergen-specific IgE, an allergen-specific T cell response, and the release of biologically active mediators such as histamine from mast cells and basophils. Regimens permanently tolerizing an allergic immune response still need to be developed. We therefore retrovirally transduced murine hematopoietic stem cells to express the major grass pollen allergen Phl p 5 on their cell membrane. Transplantation of these genetically modified hematopoietic stem cells led to durable multilineage molecular chimerism and permanent immunological tolerance toward the introduced allergen at the B cell, T cell, and effector cell levels. Notably, Phl p 5-specific serum IgE and IgG remained undetectable, and T cell nonresponsiveness persisted throughout follow-up (40 wk). Besides, mediator release was specifically absent in in vitro and in vivo assays. B cell, T cell, and effector cell responses to an unrelated control allergen (Bet v 1) were unperturbed, demonstrating specificity of this tolerance protocol. We thus describe a novel cell-based strategy for the prevention of allergy.
ALeishmaniaOrtholog of Macrophage Migration Inhibitory Factor Modulates Host Macrophage Responses
Authors: Kamir Daniela , Zierow Swen , Leng Lin , Cho Yoonsang , Diaz Yira , Griffith Jason , McDonald Courtney , Merk Melanie , Mitchell Robert A. , Trent John , Chen Yibang , Kwong Yuen-Kwan Amy , Xiong Huabao , Vermeire Jon , Cappello Michael , McMahon-Pratt Diane , Walker John , Bernhagen Jurgen , Lolis Elias , Bucala Richard 
Published: April 2014

AbstractParasitic organisms have evolved specialized strategies to evade immune defense mechanisms. We describe herein an ortholog of the cytokine, macrophage migration inhibitory factor (MIF), which is produced by the obligate intracellular parasite, Leishmania major. The Leishmania MIF protein, Lm1740MIF, shows significant structural homology with human MIF as revealed by a high-resolution x-ray crystal structure (1.03 Å). Differences between the two proteins in the N-terminal tautomerization site are evident, and we provide evidence for the selective, species-specific inhibition of MIF by small-molecule antagonists that target this site. Lm1740MIF shows significant binding interaction with the MIF receptor, CD74 (Kd = 2.9 × 10−8 M). Like its mammalian counterpart, Lm1740MIF induces ERK1/2 MAP kinase activation in a CD74-dependent manner and inhibits the activation-induced apoptosis of macrophages. The ability of Lm1740MIF to inhibit apoptosis may facilitate the persistence of Leishmania within the macrophage and contribute to its evasion from immune destruction.
Pattern of Proinflammatory Cytokine Induction in RAW264.7 Mouse Macrophages Is Identical for Virulent and AttenuatedBorrelia burgdorferi
Authors: Wang Guiqing , Petzke Mary M. , Iyer Radha , Wu Hongyan , Schwartz Ira 
Published: April 2014

AbstractLyme disease pathogenesis results from a complex interaction between Borrelia burgdorferi and the host immune system. The intensity and nature of the inflammatory response of host immune cells to B. burgdorferi may be a determining factor in disease progression. Gene array analysis was used to examine the expression of genes encoding cytokines, chemokines, and related factors in the joint tissue of infected C3H/HeJ mice and in a murine macrophage-like cell line in response to a disseminating or attenuated clinical isolate of B. burgdorferi. Both isolates elicited a robust proinflammatory response in RAW264.7 cells characterized by an increase in transcript levels of genes encoding CC and CXC chemokines, proinflammatory cytokines, and TNF superfamily members. Transcription of genes encoding IL-1β, IL-6, MCP-1, MIP-1α, CXCR4, and TLR2 induced in RAW264.7 cells by either live or heat-killed spirochetes did not differ significantly at any time point over a 24-h period, nor was there a difference in the protein levels of IL-10, TNF-α, IL-6, and IL-12p70 in culture supernatants. Thus, induction of host macrophage expression of proinflammatory mediators by host macrophages does not contribute to the differential pathogenicity of different B. burgdorferi strains.
Role of the RNA-Binding Protein Tristetraprolin in Glucocorticoid-Mediated Gene Regulation
Authors: Ishmael Faoud T. , Fang Xi , Galdiero Maria Rosaria , Atasoy Ulus , Rigby William F. C. , Gorospe Myriam , Cheadle Chris , Stellato Cristiana 
Published: April 2014

Abstract
Glucocorticoids (GCs) are the mainstay of anti-inflammatory therapy. Modulation of posttranscriptional regulation (PTR) of gene expression by GCs is a relevant yet poorly characterized mechanism of their action. The RNA-binding protein tristetraprolin (TTP) plays a central role in PTR by binding to AU-rich elements in the 3′-untranslated region of proinflammatory transcripts and accelerating their decay. We found that GCs induce TTP expression in primary and immortalized human bronchial epithelial cells. To investigate the importance of PTR and the role of TTP in GC function, we compared the effect of GC treatment on genome-wide gene expression using mouse embryonic fibroblasts (MEFs) obtained from wild-type and TTP−/− mice. We confirmed that GCs induce TTP in MEFs and observed in TTP−/− MEFs a striking loss of up to 85% of GC-mediated gene expression. Gene regulation by TNF-α was similarly affected, as was the antagonistic effect of GC on TNF-α-induced response. Inflammatory genes, including cytokines and chemokines, were among the genes whose sensitivity to GCs was affected by lack of TTP. Silencing of TTP in WT MEFs by small interfering RNA confirmed loss of GC response in selected targets. Immunoprecipitation of ribonucleoprotein complexes revealed binding of TTP to several validated transcripts. Changes in the rate of transcript degradation studied by actinomycin D were documented for only a subset of transcripts bound to TTP. These results reveal a strong and previously unrecognized contribution of PTR to the anti-inflammatory action of GCs and point at TTP as a key factor mediating this process through a complex mechanism of action.
CD4+ T Cells Target Epitopes Residing within the RNA-Binding Domain of the U1-70-kDa Small Nuclear Ribonucleoprotein Autoantigen and Have Restricted TCR Diversity in an HLA-DR4-Transgenic Murine Model of Mixed Connective Tissue Disease
Authors: Greidinger Eric L. , Zang Yun Juan , Jaimes Kimberly , Martinez Laisel , Nassiri Mehdi , Hoffman Robert W. 
Published: April 2014

Abstract
Mixed connective tissue disease (MCTD) is a systemic autoimmune disease with significant morbidity and premature mortality of unknown pathogenesis. In the present study, we characterized U1-70-kDa small nuclear ribonucleoprotein (70-kDa) autoantigen-specific T cells in a new murine model of MCTD. These studies defined 70-kDa-reactive T cell Ag fine specificities and TCR gene usage in this model. Similar to patients with MCTD, CD4+ T cells can be readily identified from 70-kDa/U1-RNA-immunized HLA-DR4-transgenic mice. Using both freshly isolated CD4+ T cells from spleen and lung, and T cell lines, we found that the majority of these T cells were directed against antigenic peptides residing within the RNA-binding domain of 70 kDa. We also found that TCR-β (TRB) V usage was highly restricted among 70-kDa-reactive T cells, which selectively used TRBV subgroups 1, 2, 6, 8.1, 8.2, and 8.3, and that the TRB CDR3 had conserved sequence motifs which were shared across different TRBV subgroups. Finally, we found that the TRBV and CDR3 regions used by both murine and human 70-kDa-specific CD4+ T cells were homologous. Thus, T cell recognition of the 70-kDa autoantigen by HLA-DR4-transgenic mice is focused on a limited number of T cell epitopes residing primarily within the RBD of the molecule, using a restricted number of TRBV and CDR3 motifs that are homologous to T cells isolated from MCTD patients.
Distinct Structural Requirements of GATA-3 for the Regulation of Thymocyte and Th2 Cell Differentiation
Authors: Pai Sung-Yun , Kang Bok Yun , Sabadini Amelia M. , Parisini Emilio , Truitt Morgan L. , Ho I-Cheng 
Published: April 2014

Abstract
GATA-3, the only T cell-specific member of the GATA family of transcription factors, is essential for the intrathymic development of CD4+ T cells and for the differentiation of Th2 cells. However, whether distinct biochemical features, unique to GATA-3 compared with other GATA family members, are required to drive T cell transcriptional programs or whether the T cell-specific functions of GATA-3 can simply be ascribed to its expression pattern is unclear. Nor do we understand the protein structural requirements for each individual function of GATA-3. In this study, we report that a heterologous GATA factor, GATA-4, was competent in supporting the development of CD4+ T cells but could not fully compensate for GATA-3 in regulating the expression of Th cytokines. Specifically, GATA-3 was more potent than GATA-4 in driving the production of IL-13 due to a mechanism independent of DNA binding or chromatin remodeling of the IL-13 locus. The difference was mapped to a partially conserved region C-terminal to the second zinc finger. Converting a single proline residue located in this region of GATA-4 to its counterpart, a methionine of GATA-3, was sufficient to enhance the IL-13-promoting function of GATA-4 but had no effect on other cytokines. Taken together, our data demonstrate that the unique function of GATA-3 is conferred by both its cell type-specific expression and distinct protein structure.
Differential Activation of Human TLR4 by Escherichia coli and Shigella flexneri 2a Lipopolysaccharide: Combined Effects of Lipid A Acylation State and TLR4 Polymorphisms on Signaling
Authors: Rallabhandi Prasad , Awomoyi Agnes , Thomas Karen E. , Phalipon Armelle , Fujimoto Yukari , Fukase Koichi , Kusumoto Shoichi , Qureshi Nilofer , Sztein Marcelo B. , Vogel Stefanie N. 
Published: April 2014

Abstract
The lipid A of LPS activates TLR4 through an interaction with myeloid differentiation protein-2 (MD-2) and the degree of lipid A acylation affects TLR4 responsiveness. Two TLR4 single nucleotide polymorphisms (Asp299Gly and Thr399Ile) have been associated with LPS hyporesponsiveness. We hypothesized that the combination of hypoacylation and these single nucleotide polymorphisms would exhibit a compounded effect on TLR4 signaling. HEK293T transfectants expressing wild-type or polymorphic TLR4 were stimulated with Escherichia coli (predominantly hexaacylated lipid A) or Shigella flexneri 2a (a mixture of hexaacylated, pentaacylated, and predominantly tetraacylated lipid A) LPS, or hexaacylated vs pentaacylated synthetic lipid As. NF-κB-reporter activity was significantly lower in response to S. flexneri 2a than E. coli LPS and further decreased in polymorphic transfectants. Neither hexaacylated nor pentaacylated synthetic lipid A induced NF-κB activity in wild-type transfectants under the identical transfection conditions used for LPS; however, increasing human MD-2 expression rescued responsiveness to hexaacylated lipid A only, while murine MD-2 was required to elicit a response to pentaacylated lipid A. Adherent PBMC of healthy volunteers were also compared for LPS-induced TNF-α, IL-6, IL-1β, and IL-10 production. Cytokine levels were significantly lower (∼20–90%) in response to S. flexneri than to E. coli LPS/lipid A and PBMC from polymorphic individuals secreted decreased cytokine levels in response to both LPS types and failed to respond to pentaacylated lipid A. Thus, the combination of acylation state and host genetics may significantly impact vaccine immunogenicity and/or efficacy, whether LPS is an integral component of a whole organism vaccine or included as an adjuvant.
Syk Associates with Clathrin and Mediates Phosphatidylinositol 3-Kinase Activation during Human Rhinovirus Internalization
Authors: Lau Christine , Wang Xiaomin , Song Lihua , North Michelle , Wiehler Shahina , Proud David , Chow Chung-Wai 
Published: April 2014

Abstract
Human rhinovirus (HRV) causes the common cold. The most common acute infection in humans, HRV is a leading cause of exacerbations of asthma and chronic obstruction pulmonary disease because of its ability to exacerbate airway inflammation by altering epithelial cell biology upon binding to its receptor, ICAM-1. ICAM-1 regulates not only viral entry and replication but also signaling pathways that lead to inflammatory mediator production. We recently demonstrated the Syk tyrosine kinase to be an important mediator of HRV-ICAM-1 signaling: Syk regulates replication-independent p38 MAPK activation and IL-8 expression. In leukocytes, Syk regulates receptor-mediated internalization via PI3K. Although PI3K has been shown to regulate HRV-induced IL-8 expression and clathrin-mediated endocytosis of HRV, the role of airway epithelial Syk in this signaling pathway is not known. We postulated that Syk regulates PI3K activation and HRV endocytosis in the airway epithelium. Using confocal microscopy and immunoprecipitation, we demonstrated recruitment of the normally cytosolic Syk to the plasma membrane upon HRV16-ICAM-1 binding, along with Syk-clathrin coassociation. Subsequent incubation at 37°C to permit internalization revealed redistribution of Syk to punctate structures resembling endosomes and colocalization with HRV16. Internalized HRV was not detected in cells overexpressing the kinase inactive SykK396R mutant, indicating that kinase activity was necessary for endocytosis. HRV-induced PI3K activation was dependent on Syk; Syk knockdown by small interfering RNA significantly decreased phosphorylation of the PI3K substrate Akt. Together, these data reveal Syk to be an important mediator of HRV endocytosis and HRV-induced PI3K activation.