bluuebunny/crossref_metadata_2025_split huggingface dataset:
Functional Requirements for Signaling through the Stimulatory and Inhibitory Mouse NKR-P1 (CD161) NK Cell Receptors
Authors: Ljutic Belma , Carlyle James R. , Filipp Dominik , Nakagawa Rinako , Julius Michael , Zúñiga-Pflücker Juan Carlos 
Published: April 2014

AbstractThe NK cell receptor protein 1 (NKR-P1) (CD161) molecules represent a family of type II transmembrane C-type lectin-like receptors expressed predominantly by NK cells. Despite sharing a common NK1.1 epitope, the mouse NKR-P1B and NKR-P1C receptors possess opposing functions in NK cell signaling. Engagement of NKR-P1C stimulates cytotoxicity of target cells, Ca2+ flux, phosphatidylinositol turnover, kinase activity, and cytokine production. In contrast, NKR-P1B engagement inhibits NK cell cytotoxicity. Nonetheless, it remains unclear how different signaling outcomes are mediated at the molecular level. Here, we demonstrate that both NKR-P1B and NKR-P1C associate with the tyrosine kinase, p56lck. The interaction is mediated through the di-cysteine CxCP motif in the cytoplasmic domains of NKR-P1B/C. Disrupting this motif leads to abrogation of both stimulatory and inhibitory NKR-P1 signals. In addition, mutation of the consensus ITIM (LxYxxL) in NKR-P1B abolishes both its Src homology 2-containing protein tyrosine phosphatase-1 recruitment and inhibitory function. Strikingly, engagement of NKR-P1C on NK cells obtained from Lck-deficient mice failed to induce NK cytotoxicity. These results reveal a role for Lck in the initiation of NKR-P1 signals, and demonstrate a requirement for the ITIM in NKR-P1-mediated inhibition.
Increased Immunogenicity of an Anchor-Modified Tumor-Associated Antigen Is Due to the Enhanced Stability of the Peptide/MHC Complex: Implications for Vaccine Design
Authors: Borbulevych Oleg Y. , Baxter Tiffany K. , Yu Zhiya , Restifo Nicholas P. , Baker Brian M. 
Published: April 2014

AbstractThe use of “anchor-fixed” altered peptide ligands is of considerable interest in the development of therapeutic vaccines for cancer and infectious diseases, but the mechanism by which successful altered peptide ligands elicit enhanced immunity is unclear. In this study, we have determined the crystallographic structure of a major tumor rejection Ag, gp100209–217, in complex with the HLA-A*0201 (HLA-A2) molecule, as well as the structure of a modified version of the peptide which substitutes methionine for threonine at position 2 (T2M; gp100209–2M). The T2M-modified peptide, which is more immunogenic in vitro and in vivo, binds HLA-A2 with a ∼9-fold greater affinity and has a ∼7-fold slower dissociation rate at physiological temperature. Within the limit of the crystallographic data, the T2M substitution does not alter the structure of the peptide/HLA-A2 complex. Consistent with this finding, in peripheral blood from 95 human subjects, we were unable to identify higher frequencies of T cells specific for either the native or modified peptide. These data strongly support the conclusion that the greater immunogenicity of the gp100209–2M peptide is due to the enhanced stability of the peptide/MHC complex, validating the anchor-fixing approach for generating therapeutic vaccine candidates. Thermodynamic data suggest that the enhanced stability of the T2M-modified peptide/HLA-A2 complex is attributable to the increased hydrophobicity of the modified peptide, but the gain due to hydrophobicity is offset considerably by the loss of a hydrogen bond made by the native peptide to the HLA-A2 molecule. Our findings have broad implications for the optimization of current vaccine-design strategies.
Microbial Antigen Triggers Rapid Mobilization of TNF-α to the Surface of Mouse Neutrophils Transforming Them into Inducers of High-Level Dendritic Cell TNF-α Production
Authors: Bennouna Soumaya , Denkers Eric Y. 
Published: April 2014

AbstractNeutrophils play a critical role in early immunity to many microbial pathogens, and this may in part be due to their ability to release immunoregulatory cytokines and chemokines during infection. Here, we demonstrate by flow cytometric analysis that mouse polymorphonuclear leukocytes (PMN) up-regulate surface expression of TNF-α within 10 min of stimulation with LPS, and that this is followed by gradual loss over a period of 18 h. Early increases in surface TNF-α expression correlated with loss of intracellular pools of preformed TNF-α. Nevertheless, extended incubation with LPS resulted in increased levels of TNF-α mRNA synthesis and replenishment of intracellular cytokine. After triggering with LPS, PMN acquired the ability to induce dendritic cell (DC) TNF-α and IL-12 production. Transwell assays demonstrated that high-level DC TNF-α production induced by LPS-triggered neutrophils was dependent upon cell-to-cell contact and neutrophil TNF-α, but neither was required for neutrophil instruction of DC IL-12 synthesis. The data suggest that microbial Ag-triggered mouse PMN acquire the capacity to deliver potent DC-activating signals through elaboration of cytokines and direct interactions at the cell surface.
Roles for CXC Chemokine Ligands 10 and 11 in Recruiting CD4+ T Cells to HIV-1-Infected Monocyte-Derived Macrophages, Dendritic Cells, and Lymph Nodes
Authors: Foley John F. , Yu Cheng-Rong , Solow Rikki , Yacobucci Maureen , Peden Keith W. C. , Farber Joshua M. 
Published: April 2014

AbstractWe investigated roles for chemoattractants in dissemination of HIV-1 by examining the induction of T cell-active chemokines in HIV-1-infected human monocyte-derived macrophages and dendritic cells. Of the 12 chemokines analyzed, mRNAs for two, CXCL10 and CXCL11, ligands for the chemokine receptor CXCR3, were up-regulated in both cell types upon infection by HIV-1. Induction of these chemokine genes in infected cultures was dependent on both viral entry and reverse transcriptase activity, but not on the HIV-1 envelope glycoprotein. Conditioned medium from infected cells was chemotactic for freshly isolated human CD4+ T cells, and chemotaxis was abolished by pretreatment with an Ab against CXCR3. A lymph node from an HIV-1-infected individual expressed CXCL10 and CXCL11 mRNAs in the paracortex, including venules, as detected by in situ hybridization, whereas neither mRNA was detected after highly active antiretroviral therapy. Because CCR5 on CD4+ T cells is found predominantly on cells that also express CXCR3, these data implicate CXCL10 and CXCL11 in the recruitment of susceptible T cells to HIV-1-infected lymph nodes, macrophages, and dendritic cells. This recruitment might enhance the sequestration of T cells in infected lymphoid organs and the spread of infection between cells, contributing to the immunopathology of AIDS.
Cathelicidin Mediates Innate Intestinal Defense against Colonization with Epithelial Adherent Bacterial Pathogens
Authors: Iimura Mitsutoshi , Gallo Richard L. , Hase Koji , Miyamoto Yukiko , Eckmann Lars , Kagnoff Martin F. 
Published: April 2014

AbstractCathelicidin-related antimicrobial peptide (mCRAMP), the sole murine cathelicidin, is encoded by the gene Cnlp. We show that mCRAMP expression in the intestinal tract is largely restricted to surface epithelial cells in the colon. Synthetic mCRAMP had antimicrobial activity against the murine enteric pathogen Citrobacter rodentium, which like the related clinically important human pathogens enteropathogenic Escherichia coli and enterohemorrhagic E. coli, adheres to the apical membrane of intestinal epithelial cells. Colon epithelial cell extracts from Cnlp+/+ mice had significantly greater antimicrobial activity against C. rodentium than those of mutant Cnlp−/− mice that lack mCRAMP. Cnlp−/− mice developed significantly greater colon surface and crypt epithelial cell colonization, surface epithelial cell damage, and systemic dissemination of infection than Cnlp+/+ mice after oral infection with C. rodentium. Moreover, Cnlp+/+ mice were protected from oral infections with C. rodentium inocula that infected the majority of Cnlp−/− mice. These results establish cathelicidin as an important component of innate antimicrobial defense in the colon.
Removal of Regulatory T Cell Activity Reverses Hyporesponsiveness and Leads to Filarial Parasite Clearance In Vivo
Authors: Taylor Matthew D. , LeGoff Laetitia , Harris Anjanette , Malone Eva , Allen Judith E. , Maizels Rick M. 
Published: April 2014

AbstractHuman filarial parasites cause chronic infection associated with long-term down-regulation of the host’s immune response. We show here that CD4+ T cell regulation is the main determinant of parasite survival. In a laboratory model of infection, using Litomosoides sigmodontis in BALB/c mice, parasites establish for &gt;60 days in the thoracic cavity. During infection, CD4+ T cells at this site express increasing levels of CD25, CTLA-4, and glucocorticoid-induced TNF receptor family-related gene (GITR), and by day 60, up to 70% are CTLA-4+GITRhigh, with a lesser fraction coexpressing CD25. Upon Ag stimulation, CD4+CTLA-4+GITRhigh cells are hyporesponsive for proliferation and cytokine production. To test the hypothesis that regulatory T cell activity maintains hyporesponsiveness and prolongs infection, we treated mice with Abs to CD25 and GITR. Combined Ab treatment was able to overcome an established infection, resulting in a 73% reduction in parasite numbers (p &lt; 0.01). Parasite killing was accompanied by increased Ag-specific immune responses and markedly reduced levels of CTLA-4 expression. The action of the CD25+GITR+ cells was IL-10 independent as in vivo neutralization of IL-10R did not restore the ability of the immune system to kill parasites. These data suggest that regulatory T cells act, in an IL-10-independent manner, to suppress host immunity to filariasis.
Anthrax Edema Toxin Cooperates with Lethal Toxin to Impair Cytokine Secretion during Infection of Dendritic Cells
Authors: Tournier Jean-Nicolas , Quesnel-Hellmann Anne , Mathieu Jacques , Montecucco Cesare , Tang Wei-Jen , Mock Michèle , Vidal Dominique R. , Goossens Pierre L. 
Published: April 2014

AbstractBacillus anthracis secretes two critical virulence factors, lethal toxin (LT) and edema toxin (ET). In this study, we show that murine bone marrow-derived dendritic cells (DC) infected with B. anthracis strains secreting ET exhibit a very different cytokine secretion pattern than DC infected with B. anthracis strains secreting LT, both toxins, or a nontoxinogenic strain. ET produced during infection selectively inhibits the production of IL-12p70 and TNF-α, whereas LT targets IL-10 and TNF-α production. To confirm the direct role of the toxins, we show that purified ET and LT similarly disrupt cytokine secretion by DC infected with a nontoxinogenic strain. These effects can be reversed by specific inhibitors of each toxin. Furthermore, ET inhibits in vivo IL-12p70 and IFN-γ secretion induced by LPS. These results suggest that ET produced during infection impairs DC functions and cooperates with LT to suppress the innate immune response. This may represent a new strategy developed by B. anthracis to escape the host immune response.
Activation-Induced Depletion of Protein Kinase Cα Provokes Desensitization of Monocytes/Macrophages in Sepsis
Authors: von Knethen Andreas , Tautenhahn Anja , Link Hartmut , Lindemann Dirk , Brüne Bernhard 
Published: April 2014

AbstractSepsis accounts for the majority of fatal casualties in critically ill patients, because extensive research failed to significantly improve appropriate therapy strategies. Thus, understanding molecular mechanisms initiating the septic phenotype is important. Symptoms of septic disease are often associated with monocyte/macrophage desensitization. In this study, we provide evidence that a desensitized cellular phenotype is characterized by an attenuated oxidative burst. Inhibition of the oxidative burst and depletion of protein kinase Cα (PKCα) were correlated in septic patients. To prove that PKCα down-regulation indeed attenuated the oxidative burst, we set up a cell culture model to mimic desensitized monocytes/macrophages. We show that LPS/IFN-γ-treatment of RAW264.7 and U937 cells lowered PKCα expression and went on to confirm these data in primary human monocyte-derived macrophages. To establish a role of PKCα in cellular desensitization, we overexpressed PKCα in RAW264.7 and U937 cells and tested for phorbolester-elicited superoxide formation following LPS/IFN-γ-pretreatment. Inhibition of the oxidative burst, i.e., cellular desensitization, was clearly reversed in cells overexpressing PKCα, pointing to PKCα as the major transmitter in eliciting the oxidative burst in monocytes/macrophages. However, PKCα inactivation by transfecting a catalytically inactive PKCα mutant attenuated superoxide formation. We suggest that depletion of PKCα in monocytes from septic patients contributes to cellular desensitization, giving rise to clinical symptoms of sepsis.
TLR2 Signaling in Chondrocytes Drives Calcium Pyrophosphate Dihydrate and Monosodium Urate Crystal-Induced Nitric Oxide Generation
Authors: Liu-Bryan Ru , Pritzker Kenneth , Firestein Gary S. , Terkeltaub Robert 
Published: April 2014

Abstract
Microcrystals of calcium pyrophosphate dihydrate (CPPD) and monosodium urate (MSU) deposited in synovium and articular cartilage initiate joint inflammation and cartilage degradation in large part by binding and directly activating resident cells. TLRs trigger innate host defense responses to infectious pathogens, and the expression of certain TLRs by synovial fibroblasts has revealed the potential for innate immune responses to be triggered by mesenchymally derived resident cells in the joint. In this study we tested the hypothesis that chondrocytes also express TLRs and that one or more TLRs centrally mediate chondrocyte responsiveness to CPPD and MSU crystals in vitro. We detected TLR2 expression in normal articular chondrocytes and up-regulation of TLR2 in osteoarthritic cartilage chondrocytes in situ. We demonstrated that transient transfection of TLR2 signaling-negative regulator Toll-interacting protein or treatment with TLR2-blocking Ab suppressed CPPD and MSU crystal-induced chondrocyte release of NO, an inflammatory mediator that promotes cartilage degeneration. Conversely, gain-of-function of TLR2 in normal chondrocytes via transfection was associated with increased CPPD and MSU crystal-induced NO release. Canonical TLR signaling by parallel pathways involving MyD88, IL-1R-associated kinase 1, TNF receptor-associated factor 6, and IκB kinase and Rac1, PI3K, and Akt critically mediated NO release in chondrocytes stimulated by both CPPD and MSU crystals. We conclude that CPPD and MSU crystals critically use TLR2-mediated signaling in chondrocytes to trigger NO generation. Our results indicate the potential for innate immunity at the level of the articular chondrocyte to directly contribute to inflammatory and degenerative tissue reactions associated with both gout and pseudogout.
Allergen Drives Class Switching to IgE in the Nasal Mucosa in Allergic Rhinitis
Authors: Takhar Pooja , Smurthwaite Lyn , Coker Heather A. , Fear David J. , Banfield Graham K. , Carr Victoria A. , Durham Stephen R. , Gould Hannah J. 
Published: April 2014

AbstractIgE-expressing B cells are over 1000 times more frequent in the nasal B cell than the peripheral blood B cell population. We have investigated the provenance of these B cells in the nasal mucosa in allergic rhinitis. It is generally accepted that expression of activation-induced cytidine deaminase and class switch recombination (CSR) occur in lymphoid tissue, implying that IgE-committed B cells must migrate through the circulation to the nasal mucosa. Our detection of mRNA for activation-induced cytidine, multiple germline gene transcripts, and ε circle transcripts in the nasal mucosa of allergic, in contrast to nonallergic control subjects, however, indicates that local CSR occurs in allergic rhinitis. The germline gene transcripts and ε circle transcripts in grass pollen-allergic subjects are up-regulated during the season and also when biopsies from allergic subjects are incubated with the allergen ex vivo. These results demonstrate that allergen stimulates local CSR to IgE, revealing a potential target for topical therapies in allergic rhinitis.
Cyclooxygenase 2 Plays a Pivotal Role in the Resolution of Acute Lung Injury
Authors: Fukunaga Koichi , Kohli Payal , Bonnans Caroline , Fredenburgh Laura E. , Levy Bruce D. 
Published: April 2014

Abstract
Acute lung injury (ALI) is a severe illness with excess mortality and no specific therapy. In its early exudative phase, neutrophil activation and accumulation in the lung lead to hypoxemia, widespread tissue damage, and respiratory failure. In clinical trials, inhibition of proinflammatory mediators has not proven effective. In this study, we pursued a new investigative strategy that emphasizes mediators promoting resolution from lung injury. A new spontaneously resolving experimental murine model of ALI from acid aspiration was developed to identify endogenous proresolving mechanisms. ALI increased cyclooxygenase 2 (COX-2) expression in murine lung. Selective pharmacologic inhibition or gene disruption of COX-2 blocked resolution of ALI. COX-2-derived products increased levels of the proresolving lipid mediators lipoxin A4 (LXA4) and, in the presence of aspirin, 15-epi-LXA4. Both LXA4 and 15-epi-LXA4 interact with the LXA4 receptor (ALX) to mediate anti-inflammatory actions. ALX expression was markedly induced by acid injury and transgenic mice with increased ALX expression displayed dramatic protection from ALI. Together, these findings indicate a protective role in ALI for COX-2-derived mediators, in part via enhanced lipoxin signaling, and carry potential therapeutic implications for this devastating clinical disorder.
ERK1/2 Regulates Epidermal Chemokine Expression and Skin Inflammation
Authors: Pastore Saveria , Mascia Francesca , Mariotti Feliciana , Dattilo Cristina , Mariani Valentina , Girolomoni Giampiero 
Published: April 2014

AbstractResident cell populations of the skin contribute to the inflammatory response by producing an array of chemokines, which attract leukocytes from the circulation. TNF-α is a major inducer of proinflammatory mediators in keratinocytes. We have recently observed that epidermal growth factor receptor (EGFR) signaling affects TNF-α-driven chemokine expression in epidermal keratinocytes, and its functional impairment increases the levels of crucial chemoattractants such as CCL2/MCP-1, CCL5/RANTES, and CXCL10/IFN-γ-inducible protein-10. In this study, we report evidence that EGFR-dependent ERK1/2 activity is implicated in this mechanism. Abrogation of ERK1/2 activity with specific inhibitors increased chemokine expression in keratinocytes by enhancing mRNA stabilization. In mouse models, inflammatory response to irritants and T cell-mediated contact hypersensitivity were both aggravated when elicited in a skin area previously treated with an EGFR or a MAPK kinase 1/2 inhibitor. In contrast, impairment of p38αβ MAPK phosphorylation markedly attenuated these responses. Our data indicate that EGFR-dependent ERK1/2 activity in keratinocytes takes part to a homeostatic mechanism regulating inflammatory responses, and emphasize the distinct role of MAPKs as potential targets for manipulating inflammation in the skin.
Fibrin Deimination in Synovial Tissue Is Not Specific for Rheumatoid Arthritis but Commonly Occurs during Synovitides
Authors: Chapuy-Regaud Sabine , Sebbag Mireille , Baeten Dominique , Clavel Cyril , Foulquier Céline , De Keyser Filip , Serre Guy 
Published: April 2014

AbstractAutoantibodies to deiminated (citrullinated) proteins are the most specific serological markers of rheumatoid arthritis (RA). Deimination is critical in generating the peptidic epitopes they recognize. In the synovial tissue (ST), deiminated forms of the α- and β-chains of fibrin are their major autoantigenic targets (anti-human fibrin(ogen) autoantibodies (AhFibA)). We investigated whether the presence of deiminated fibrin in the ST was specific for RA, because this could explain why AhFibA are RA specific. In 13 patients with RA and 19 patients with various other rheumatological disorders, knee ST biopsies were collected in macroscopically inflamed areas identified under arthroscopy. Synovitis was histopathologically confirmed in all of the biopsies. By immunoblotting, using antisera to fibrin, Abs to citrullyl residues, and AhFibA purified from RA sera, deiminated fibrin was evidenced in ST extracts from all of the patients. Moreover, variations in the degree of fibrin deimination were observed that were not related to the disease. Immunohistochemical analysis, using Abs to citrullyl residues and an antiserum to fibrin on adjacent serial sections of ST, confirmed the results because deiminated proteins colocalized with fibrin in RA as well as in control patients. Therefore, fibrin deimination in the ST is a general phenomenon associated to any synovitis, which does not necessarily induce a B autoimmune response with production of AhFibA.
CD4+ T Cell Responses to SSX-4 in Melanoma Patients
Authors: Ayyoub Maha , Merlo Andrea , Hesdorffer Charles S. , Rimoldi Donata , Speiser Daniel , Cerottini Jean-Charles , Chen Yao-Tseng , Old Lloyd J. , Stevanovic Stefan , Valmori Danila 
Published: April 2014

Abstract
Genes of the synovial sarcoma X breakpoint (SSX) family are expressed in different human tumors, including melanomas, but not in adult somatic tissues. Because of their specific expression at the tumor site, SSX-encoded Ags are potential targets for anticancer immunotherapy. In this study, we have analyzed CD4+ T cell responses directed against the Ag encoded by SSX-4. Upon in vitro stimulation of PBMC from four melanoma patients bearing Ag-expressing tumors with a pool of long peptides spanning the protein sequence, we detected and isolated SSX-4-specific CD4+ T cells recognizing several distinct antigenic sequences, mostly restricted by frequently expressed HLA class II alleles. The majority of the identified sequences were located within the Krüppel-associated box domain in the N-terminal region of the protein, indicating a high potential immunogenicity of this region. Together our data document the existence of CD4+ T cells specific for multiple SSX-4 derived sequences in circulating lymphocytes from melanoma patients and encourage further studies to assess the impact of SSX-4-specific T cell responses on disease evolution in cancer patients.