bluuebunny/crossref_metadata_2025_split huggingface dataset:
Bovine Peptidoglycan Recognition Protein-S: Antimicrobial Activity, Localization, Secretion, and Binding Properties
Authors: Tydell C. Chace , Yuan Jun , Tran Patti , Selsted Michael E. 
Published: April 2014

Abstract
Peptidoglycan (PGN) recognition proteins (PGRPs) are pattern recognition molecules of innate immunity that are conserved from insects to humans. Various PGRPs are reported to have diverse functions: they bind bacterial molecules, digest PGN, and are essential to the Toll pathway in Drosophila. One family member, bovine PGN recognition protein-S (bPGRP-S), has been found to bind and kill microorganisms in a PGN-independent manner, raising questions about the identity of the bPGRP-S ligand. Addressing this, we have determined the binding and microbicidal properties of bPGRP-S in a range of solutions approximating physiologic conditions. In this study we show that bPGRP-S interacts with other bacterial components, including LPS and lipoteichoic acid, with higher affinities than for PCP, as determined by their abilities to inhibit bPGRP-S-mediated killing of bacteria. Where and how PGRPs act in vivo is not yet clear. Using Immunogold electron microscopy, PGRP-S was localized to the dense/large granules of naive neutrophils, which contain the oxygen-independent bactericidal proteins of these cells, and to the neutrophil phagolysosome. In addition, Immunogold staining and secretion studies demonstrate that neutrophils secrete PGRP-S when exposed to bacteria. Bovine PGRP-S can mediate direct lysis of heat-killed bacteria; however, PGRP-S-mediated killing of bacteria is independent of this activity. Evidence that bPGRP-S has multiple activities and affinity to several bacterial molecules challenges the assumption that the PGRP family of proteins recapitulates the evolution of TLRs. Mammalian PGRPs do not have a single antimicrobial activity against a narrow range of target organisms; rather, they are generalists in their affinity and activity.
Extracellular Acidosis Induces Neutrophil Activation by a Mechanism Dependent on Activation of Phosphatidylinositol 3-Kinase/Akt and ERK Pathways
Authors: Martínez Diego , Vermeulen Mónica , Trevani Analía , Ceballos Ana , Sabatté Juan , Gamberale Romina , Álvarez María Eugenia , Salamone Gabriela , Tanos Tamara , Coso Omar A. , Geffner Jorge 
Published: April 2014

Abstract
Inflammation in peripheral tissues is usually associated with the development of local acidosis; however, there are few studies aimed at analyzing the influence of acidosis on immune cells. We have shown previously that extracellular acidosis triggers human neutrophil activation, inducing a transient increase in intracellular Ca2+ concentration, a shape change response, the up-regulation of CD18 expression, and a delay of apoptosis. In this study, we analyzed the signaling pathways responsible for neutrophil activation. We found that acidosis triggers the phosphorylation of Akt (the main downstream target of PI3K) and ERK MAPK, but not that of p38 and JNK MAPK. No degradation of IκB was observed, supporting the hypothesis that NF-κB is not activated under acidosis. Inhibition of PI3K by wortmannin or LY294002 markedly decreased the shape change response and the induction of Ca2+ transients triggered by acidosis, whereas the inhibition of MEK by PD98059 or U0126 significantly inhibited the shape change response without affecting the induction of Ca2+ transients. We also found that acidosis not only induces a shape change response and the induction of Ca2+ transients in human neutrophils but also stimulates the endocytosis of FITC-OVA and FITC-dextran. Stimulation of endocytosis was partially prevented by inhibitors of PI3K and MEK. Together, our results support the notion that the stimulation of human neutrophils by extracellular acidosis is dependent on the activation of PI3K/Akt and ERK pathways. Of note, using mouse peritoneal neutrophils we observed that the enhancement of endocytosis induced by acidosis was associated with an improved ability to present extracellular Ags through a MHC class I-restricted pathway.
Pristane, a Non-Antigenic Adjuvant, Induces MHC Class II-Restricted, Arthritogenic T Cells in the Rat
Authors: Holmberg Jens , Tuncel Jonatan , Yamada Hisakata , Lu Shemin , Olofsson Peter , Holmdahl Rikard 
Published: April 2014

Abstract
Pristane-induced arthritis (PIA) in rats, a model for rheumatoid arthritis (RA), is a T cell-dependent disease. However, pristane itself is a lipid and unable to form a stable complex with a MHC class II molecule. Therefore, the specificity and function of the T cells in PIA are as unclear as in rheumatoid arthritis. In this study, we show that activated CD4+ αβT cells, which target peripheral joints, transfer PIA. The pristane-primed T cells are of oligo or polyclonal origin as determined by their arthritogenicity after stimulation with several mitogenic anti-TCRVβ and anti-TCRVα mAbs. Arthritogenic cells secreted IFN-γ and TNF-α (but not IL-4) when stimulated with Con A in vitro, and pretreatments of recipient rats with either anti-IFN-γ or a recombinant TNF-α receptor before transfer ameliorated arthritis development. Most importantly, we show that these T cells are MHC class II restricted, because treatment with Abs against either DQ or DR molecules ameliorates arthritis development. The MHC class II restriction was confirmed by transferring donor T cells to irradiated recipients that were syngenic, semiallogenic, or allogenic to MHC class II molecules, in which only syngenic and semiallogenic recipients developed arthritis. These data suggest that the in vivo administration of a non-antigenic adjuvant, like pristane, activates CD4+ αβT cells that are MHC class II restricted and arthritogenic.
TGF-β1 Released from Activated Platelets Can Induce TNF-Stimulated Human Brain Endothelium Apoptosis: A New Mechanism for Microvascular Lesion during Cerebral Malaria
Authors: Wassmer Samuel C. , de Souza J. Brian , Frère Corinne , Candal Francisco J. , Juhan-Vague Irène , Grau Georges E. 
Published: April 2014

Abstract
Platelets have recently been shown to accumulate in brain microvessels of patients with cerebral malaria and to modulate the binding of Plasmodium falciparum-infected red cells to human brain endothelium in vitro. In the present study we used a platelet-endothelial cell coculture model to investigate the mechanisms by which platelets modify the function of human brain microvascular endothelial cells (HBEC). Platelets were found to have a proapoptotic effect on TNF-activated HBEC, and this was contact-dependent, as inhibiting platelet binding prevented endothelial cell killing. We also showed that the supernatants of thrombin-activated platelets killed TNF-stimulated HBEC and that TGF-β1 was the main molecule involved in endothelial cell death, because its inhibition completely abrogated the activated-platelet supernatant effect. Our data illustrate another aspect of the duality of TGF-β1 in malaria and may provide new insights into the pathogenesis of cerebral malaria.
Abrupt Expression of TLR4 in TLR4-Deficient Macrophages Imposes a Selective Disadvantage: Genetic Evidence for TLR4-Dependent Responses to Endogenous, Nonmicrobial Stimuli
Authors: Cohn Ellen F. , Nathan Carl , Radzioch Danuta , Yu Hongwei , Xiang Zhaoying , Ding Aihao 
Published: April 2014

Abstract
TLR4 is crucial for macrophage responses to LPS. It is less clear whether TLR4 may also transduce signals from host factors, and if so, with what consequences. Immortalized bone marrow-derived macrophage cell lines, termed T4Cr and T4ko, were established from TLR4null strains, C57BL/10ScNCr and TLR4 knockout mice, respectively. Multiple transfections and selections were conducted to stably introduce TLR4 into these cell lines. Among 196 individual clones isolated, 48 expressed TLR4 on the cell surface but did not respond to LPS due to a deletion in the MyD88 gene. The remaining clones integrated TLR4 DNA into the genome but expressed neither detectable TLR4 mRNA nor TLR4 protein. To test the possibility that TLR4null cells lack modulating factors to protect against a harmful effect of TLR4, 15 stably transfected clones were generated in the presence of conditioned media from wild-type macrophages. Some of these cells expressed a small amount of TLR4 and regained responsiveness to LPS. Because no microbial ligands were available to the cell lines during their generation, signaling via endogenous ligands is likely to have occurred in TLR4-expressing, signal-competent macrophages and imposed a proliferative or other selective disadvantage. These studies support the existence of constitutive signaling via TLR4 during in vitro culture of macrophages without microbial products, and help account for the lack of reports of restoration of TLR4 expression in normally TLR4-expressing types of cells in vitro whose TLR4 genes are deleted or disrupted.
Activation of TLR-9 Induces IL-8 Secretion through Peroxynitrite Signaling in Human Neutrophils
Authors: József Levente , Khreiss Tarek , El Kebir Driss , Filep János G. 
Published: April 2014

Abstract
Bacterial DNA containing unmethylated CpG motifs is emerging as an important regulator of functions of human neutrophil granulocytes (polymorphonuclear leukocytes (PMN)). These motifs are recognized by TLR-9. Recent studies indicate that peroxynitrite (ONOO−) may function as an intracellular signal for the production of IL-8, one of the key regulators of leukocyte trafficking in inflammation. In this study we investigated whether bacterial DNA (CpG-DNA) could induce ONOO− signaling in human PMN. Human whole blood, isolated PMN (purity, &gt;95%), and high purity (&gt;99%) PMN respond to CpG-DNA, but not to calf thymus DNA, with secretion of IL-8 and, to a lesser extent, IL-6 and TNF. Methylation of cytosines in CpG-DNA resulted in a complete loss of activity. The endosomal acidification inhibitors, bafilomycin A and chloroquine, inhibited CpG-DNA-induced cytokine release from PMN. CpG-DNA-induced IL-8 mRNA expression and release was also blocked by the NO synthase inhibitor Nω-nitro-l-arginine methyl ester. CpG-DNA evoked concomitant increases in intracellular superoxide and NO levels, leading to enhanced ONOO− formation and, consequently, nuclear accumulation of c-Fos and NF-κB. Pharmacological inhibition of NF-κB activation attenuated ∼75% of CpG-DNA-evoked IL-8 release. These results identify ONOO−-dependent activation of NF-κB and c-Fos as an important mechanism that mediates PMN responses, including IL-8 gene expression and release, to bacterial DNA and unmethylated CpG motifs in particular. Enhanced ONOO− formation represents a mechanism by which bacterial DNA may contribute to prolongation and amplification of the inflammatory response.
A Potent Adjuvant Monophosphoryl Lipid A Triggers Various Immune Responses, but Not Secretion of IL-1β or Activation of Caspase-1
Authors: Okemoto Kazuo , Kawasaki Kiyoshi , Hanada Kentaro , Miura Masami , Nishijima Masahiro 
Published: April 2014

Abstract
Lipid A, the membrane anchor portion of LPS, is responsible for the endotoxin activity of LPS and induces many inflammatory responses in macrophages. Monophosphoryl lipid A (MPL), a lipid A derivative lacking a phosphate residue, induces potent immune responses with low toxicity. To elucidate the mechanism underlying the low toxicity of MPL, we examined the effects of MPL on the secretion of proinflammatory cytokines by mouse peritoneal macrophages, a murine macrophage-like cell line (RAW 264.7), and a human macrophage-like cell line (THP-1). MPL enhanced the secretion of TNF-α, but not that of IL-1β, whereas Escherichia coli-type lipid A (natural source-derived and chemically synthesized lipid A) enhanced the secretion of both cytokines. Although MPL enhanced the levels of IL-1β mRNA and IL-1β precursor protein to levels similar to those induced by lipid A, IL-1β precursor processing in MPL-treated cells was much lower than that in E. coli-type lipid A-treated ones. Moreover, MPL, unlike E. coli-type lipid A, failed to induce activation of caspase-1, which catalyzes IL-1β precursor processing. These results suggest that an immune response without activation of caspase-1 or secretion of IL-1β results in the low toxicity of this adjuvant.
Oxidants Selectively Reverse TGF-β Suppression of Proinflammatory Mediator Production
Authors: Xiao Yi Qun , Freire-de-Lima Celio G. , Janssen William J. , Morimoto Konosuke , Lyu Dennis , Bratton Donna L. , Henson Peter M. 
Published: April 2014

Abstract
Although TGF-β inhibits the production of proinflammatory mediators in vitro and in vivo, its anti-inflammatory activities may be ineffective in early or severe acute inflammatory circumstances. In this study, we suggest a role for oxidative stress on TGF-β signaling, leading to prevention of its normal anti-inflammatory effects but leaving its Smad-driven effects on cellular differentiation or matrix production unaffected. Stimulation of the RAW 264.7 macrophage cells, human or mouse alveolar macrophages with LPS led to NF-κB-driven production of proinflammatory mediators, which were inhibited by TGF-β. This inhibition was prevented in the presence of hydrogen peroxide. We found that hydrogen peroxide acted by inducing p38 MAPK activation, which then prevented the ERK activation and MAPK phosphatase-1 up-regulation normally induced by TGF-β. This was mediated through Src tyrosine kinases and protein phosphatase-1/2A. By contrast, hydrogen peroxide had no effects on TGF-β-induced Smad2 phosphorylation and SBE-luc reporter gene transcription.
Ezrin/Radixin/Moesin Proteins Are Phosphorylated by TNF-α and Modulate Permeability Increases in Human Pulmonary Microvascular Endothelial Cells
Authors: Koss McKenzie , Pfeiffer Gordon R. , Wang Ying , Thomas Sharon T. , Yerukhimovich Michael , Gaarde William A. , Doerschuk Claire M. , Wang Qin 
Published: April 2014

Abstract
Endothelial cells (ECs) respond to TNF-α by altering their F-actin cytoskeleton and junctional permeability through mechanisms that include protein kinase C (PKC) and p38 MAPK. Ezrin, radixin, and moesin (ERM) regulate many cell processes that often require a conformational change of these proteins as a result of phosphorylation on a conserved threonine residue near the C terminus. This study tested the hypothesis that ERM proteins are phosphorylated on this critical threonine residue through TNF-α-induced activation of PKC and p38 and modulate permeability increases in pulmonary microvascular ECs. TNF-α induced ERM phosphorylation on the threonine residue that required activation of p38, PKC isoforms, and phosphatidylinositol-4-phosphate 5-kinase Iα, a major enzyme generating phosphatidylinositol 4,5-bisphosphate, and phosphorylated ERM were prominently localized at the EC periphery. TNF-α-induced ERM phosphorylation was accompanied by cytoskeletal changes, paracellular gap formation, and increased permeability to fluxes of dextran and albumin. These changes required activation of p38 and PKC and were completely prevented by inhibition of ERM protein expression using small interfering RNA. Thus, ERM proteins are phosphorylated through p38 and PKC-dependent mechanisms and modulate TNF-α-induced increases in endothelial permeability. Phosphorylation of ERM likely plays important roles in EC responses to TNF-α by modulating the F-actin cytoskeleton, adhesion molecules, and signaling events.
Anti-Inflammatory Effect of Lactobacillus casei on Shigella-Infected Human Intestinal Epithelial Cells
Authors: Tien Meng-Tsung , Girardin Stephen E. , Regnault Béatrice , Le Bourhis Lionel , Dillies Marie-Agnès , Coppée Jean-Yves , Bourdet-Sicard Raphaëlle , Sansonetti Philippe J. , Pédron Thierry 
Published: April 2014

Abstract
Shigella invades the human intestinal mucosa, thus causing bacillary dysentery, an acute recto-colitis responsible for lethal complications, mostly in infants and toddlers. Conversely, commensal bacteria live in a mutualistic relationship with the intestinal mucosa that is characterized by homeostatic control of innate responses, thereby contributing to tolerance to the flora. Cross-talk established between commensals and the intestinal epithelium mediate this active process, the mechanisms of which remain largely uncharacterized. Probiotics such as Lactobacillus casei belong to a subclass of these commensals that modulate mucosal innate responses and possibly display anti-inflammatory properties. We analyzed whether L. casei could attenuate the pro-inflammatory signaling induced by Shigella flexneri after invasion of the epithelial lining. Cultured epithelial cells were infected with L. casei, followed by a challenge with S. flexneri. Using macroarray DNA chips, we observed that L. casei down-regulated the transcription of a number of genes encoding pro-inflammatory effectors such as cytokines and chemokines and adherence molecules induced by invasive S. flexneri. This resulted in an anti-inflammatory effect that appeared mediated by the inhibition of the NF-κB pathway, particularly through stabilization of I-κBα. In a time-course experiment using GeneChip hybridization analysis, the expression of many genes involved in ubiquitination and proteasome processes were modulated during L. casei treatment. Thus, L. casei has developed a sophisticated means to maintain intestinal homeostasis through a process that involves manipulation of the ubiquitin/proteasome pathway upstream of I-κBα.
Human Lung Mast Cells Adhere to Human Airway Smooth Muscle, in Part, via Tumor Suppressor in Lung Cancer-1
Authors: Yang Weidong , Kaur Davinder , Okayama Yoshimichi , Ito Akihiko , Wardlaw Andrew J. , Brightling Christopher E. , Bradding Peter 
Published: April 2014

Abstract
Mast cells infiltrate the airway smooth muscle (ASM) of patients with asthma, an event which is likely to be a key factor in the development of this disease. Adhesion is a fundamental mechanism facilitating cellular cross-talk. We have examined whether human lung mast cells (HLMC) and ASM adhere, and have also examined the mechanism involved. Primary cultures of HLMC and confluent human ASM were cocultured for 30 min, then nonadherent HLMC were removed by centrifugation. HLMC adhered avidly to ASM monolayers (mean ± SEM adhesion 43.2 ± 1.2%, n = 41). Adhesion was increased to 58.8 ± 2.7% by 1 mM Mn2+ (p = 0.015), and was reduced by EDTA and EGTA to 20.5 ± 1.5% and 21.0 ± 1.3%, respectively (p &lt; 0.0001). Adhesion-blocking Abs for ICAM-1, VCAM-1, CD18, and the α4 and β1 integrins had no effect on HLMC adhesion. HLMC expressed tumor suppressor in lung cancer-1 (TSLC-1) and blocking this reduced adhesion from 38.5 ± 4.8% to 28.3 ± 3.7% (p = 0.004, n = 7). ASM did not express TSLC-1, indicating that TSLC-1 acts as a heterophilic adhesion molecule. In summary, HLMC adhere avidly to ASM in part via TSLC-1 and in part via an as-yet-undefined Ca2+-dependent pathway. This supports the hypothesis that adhesion is important in the recruitment and retention of HLMC by the ASM in asthma, and for the functional interaction of these cells.
Defective Activation of ERK in Macrophages Lacking the p50/p105 Subunit of NF-κB Is Responsible for Elevated Expression of IL-12 p40 Observed after Challenge with Helicobacter hepaticus
Authors: Tomczak Michal F. , Gadjeva Mihaela , Wang Yan Yan , Brown Ketorah , Maroulakou Ioanna , Tsichlis Philip N. , Erdman Susan E. , Fox James G. , Horwitz Bruce H. 
Published: April 2014

Abstract
Helicobacter hepaticus is an enterohepatic Helicobacter species that induces lower bowel inflammation in susceptible mouse strains, including those lacking the p50/p105 subunit of NF-κB. H. hepaticus-induced colitis is associated with elevated levels of IL-12 p40 expression, and p50/p105-deficient macrophages express higher levels of IL-12 p40 than wild-type macrophages after challenge with H. hepaticus. However, the molecular mechanisms by which the p50/p105 subunit of NF-κB suppresses IL-12 p40 expression have not yet been elucidated. In this study we have demonstrated that H. hepaticus challenge of macrophages induces ERK activation, and this event plays a critical role in inhibiting the ability of H. hepaticus to induce IL-12 p40. Activation of ERK requires both p50/p105 and the MAPK kinase kinase, Tpl-2. Inhibition of the induction of IL-12 p40 by ERK was independent of c-Rel, a known positive regulator of IL-12 p40. Instead, it was linked to the induction of c-Fos, a known inhibitor of IL-12 p40 expression. These results suggest that H. hepaticus induces ERK activation by a pathway dependent upon Tpl-2 and p105, and that activation of ERK inhibits the expression of IL-12 p40 by inducing c-Fos. Thus, a defect in ERK activation could play a pivotal role in the superinduction of IL-12 p40 observed after challenge of macrophages lacking the p50/p105 subunit of NF-κB with H. hepaticus.
T Cell Epitope Mimicry in Antiglomerular Basement Membrane Disease
Authors: Arends Jon , Wu Jean , Borillo Jason , Troung Luan , Zhou Cindy , Vigneswaran Nadarajah , Lou Ya-Huan 
Published: April 2014

Abstract
Antiglomerular basement membrane (GBM) disease or Goodpasture’s syndrome is among the earliest recognized human autoimmune diseases. Although collagen 4α3 NC1 (Col4α3NC1) has been identified as the responsible autoantigen, it remains unknown how autoimmunity to this autoantigen is provoked. We have demonstrated in our rat model that a single nephritogenic T cell epitope pCol28–40 of Col4α3NC1 induces glomerulonephritis. We hypothesized that microbial peptides that mimic this T cell epitope could induce the disease. Based on the critical residue motif (xxtTxNPsxx) of pCol28–40, seven peptides derived from human infection-related microbes were chosen through GenBank search and synthesized. All peptides showed cross-reactivity with pCol28–40-specific T cells at various levels. Only four peptides induced transient proteinuria and minor glomerular injury. However, the other three peptides induced severe proteinuria and modest to severe glomerulonephritis in 16–25% of the immunized rats. Unexpectedly, the most nephritogenic peptide, pCB, derived from Clostridium botulinum, also induced modest (25%) to severe (25%) pulmonary hemorrhage, another important feature of anti-GBM disease; this was not correlated with the severity of glomerulonephritis. This finding suggests that subtle variations in T cell epitope specificity may lead to different clinical manifestations of anti-GBM disease. In summary, our study raises the possibility that a single T cell epitope mimicry by microbial Ag may be sufficient to induce the anti-GBM disease.