bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characterization of CD8+ Effector T Cell Responses in Volunteers Immunized with Salmonella enterica Serovar Typhi Strain Ty21a Typhoid Vaccine
Authors: Salerno-Goncalves Rosângela , Pasetti Marcela F. , Sztein Marcelo B. 
Published: April 2014

Abstract
Salmonella enterica serovar Typhi (S. typhi) strain Ty21a remains the only licensed attenuated typhoid vaccine. Despite years of research, the identity of the protective immunological mechanisms elicited by immunization with the Ty21a typhoid vaccine remains elusive. The present study was designed to characterize effector T cell responses in volunteers immunized with S. typhi strain Ty21a typhoid vaccine. We determined whether immunization with Ty21a induced specific CTL able to lyse S. typhi-infected cells and secrete IFN-γ, a key effector molecule against intracellular pathogens. We measured the functional activity of these CTL by a 51Cr-release assay using 8-day restimulated PBMC from Ty21a vaccinees as effector cells and S. Typhi-infected autologous PHA-activated PBMC as target cells. Most vaccinees exhibited consistently increased CD8-mediated lysis of targets by postimmunization PBMC when compared with preimmunization levels. We also developed an IFN-γ ELISPOT assay to quantify the frequency of IFN-γ spot-forming cells (SFC) in PBMC from Ty21a vaccinees using an ex vivo system. Significant increases in the frequency of IFN-γ SFC following immunization (mean ± SD, 393 ± 172; range 185–548 SFC/106 PBMC; p = 0.010), as compared with preimmunization levels, were observed. IFN-γ was secreted predominantly by CD8+ T cells. A strong correlation was recorded between the cytolytic activity of CTL lines and the frequency of IFN-γ SFC (r2 = 0.910, p &lt; 0.001). In conclusion, this work constitutes the first evidence that immunization of volunteers with Ty21a elicits specific CD8+ CTL and provides an estimate of the frequency of CD8+ IFN-γ-secreting cells induced by vaccination.
Role of IL-10 for Induction of Anemia During Inflammation
Authors: Tilg Herbert , Ulmer Hanno , Kaser Arthur , Weiss Günter 
Published: April 2014

Abstract
Anemia is frequently observed in patients suffering from chronic inflammatory disorders. Recent in vitro data suggest that Th2 cytokines, such as IL-10, could be involved in its pathogenesis. We analyzed 1) changes in hemoglobin values in 329 patients with chronic active Crohn’s disease receiving the anti-inflammatory cytokine IL-10 as part of a randomized, double-blind, placebo-controlled study, 2) serum iron parameters in a subgroup of these patients (n = 54), and 3) the in vitro effects of IL-10 on ferritin transcription and translation in human monocytic cells (THP-1) by means of Northern blot and immunoprecipitation after metabolic labeling. Patients receiving higher doses of IL-10 developed anemia and presented with a dose-dependent increase of ferritin and soluble transferrin receptor levels, an indicator of iron restriction to erythroid progenitor cells. According to our in vitro data, hyperferritinemia may result from direct stimulation of ferritin translation by IL-10 in activated monocytic cells, most likely by cytokine-mediated reduction of the binding affinity of translational repressors, iron-regulatory proteins, to the 5′-untranslated region of ferritin mRNA. In patients, all observed changes were most pronounced at the end of therapy (day +29), and thereafter hemoglobin levels and serum iron parameters returned to baseline levels within 4 wk of follow-up. Our data demonstrate that IL-10 causes anemia in patients with inflammatory bowel disease which may be referred to the induction of imbalances in iron homeostasis by the cytokine, leading to hyperferritinemia and limited iron availability to erythroid progenitor cells, a condition typically seen in the anemia of chronic inflammation.
Evolution of Epitope-Specific Memory CD4+ T Cells After Clearance of Hepatitis C Virus
Authors: Godkin Andrew J. , Thomas Howard C. , Openshaw Peter J. 
Published: April 2014

Abstract
The generation of memory lymphocytes is one of the hallmarks of the specific immune response. The CD4+ T cell response is of critical importance in maintaining long-term protective immunity after clearing many infections. However, accurate characterization of these memory CD4+ T cells has relied mainly on mouse studies and is poorly understood in humans. We have detected and counted epitope-specific populations of CD4+ memory cells in patients who have cleared hepatitis C virus. The kinetics of the recall response and the expression of the chemokine receptor CCR7 suggested the presence of distinct populations. A population of memory cells measured in an ex vivo IFN-γ ELISPOT assay steadily declined after viral clearance. However, memory CD4+ T cells only characterized after short-term culture with Ag and IL-2, and, recognizing the same epitopes, developed into a long-term stable population. Depletion of CCR7+ cells from PBMCs markedly reduced the responses in the culture-positive population while having little effect on the ex vivo responses. The demonstration of these key memory subsets in man opens the way to defining their role in protective immune responses.
In Situ Analysis Reveals Physical Interactions Between CD11b+ Dendritic Cells and Antigen-Specific CD4 T Cells After Subcutaneous Injection of Antigen
Authors: Ingulli Elizabeth , Ulman Deborah R. , Lucido Michelle M. , Jenkins Marc K. 
Published: April 2014

AbstractIn situ staining techniques were used to visualize physical interactions between dendritic cell subsets and naive Ag-specific CD4 T cells in the lymph node. Before injection of Ag, CD8+ dendritic cells and naive OVA-specific CD4 T cells were uniformly distributed throughout the T cell-rich paracortex, whereas CD11b+ dendritic cells were located mainly in the outer edges of the paracortex near the B cell-rich follicles. Many OVA-specific CD4 T cells were in contact with CD8+ dendritic cells in the absence of OVA. Within 24 h after s.c. injection of soluble OVA, the OVA-specific CD4 T cells redistributed to the outer paracortex and interacted with CD11b+, but not CD8+ dendritic cells. This behavior correlated with the uptake of OVA and the presence of peptide-MHC complexes on the surface of CD11b+ dendritic cells, and subsequent IL-2 production by the Ag-specific CD4 T cells. These results are consistent with the possibility that CD11b+ dendritic cells play a central role in the activation of CD4 T cells in response to s.c. Ag.
Intracellular Single-Chain Variable Fragments Directed to the Src Homology 2 Domains of Syk Partially Inhibit FcεRI Signaling in the RBL-2H3 Cell Line
Authors: Dauvillier Stéphanie , Mérida Peggy , Visintin Michela , Cattaneo Antonino , Bonnerot Christian , Dariavach Piona 
Published: April 2014

AbstractIntracellular expression of Ab fragments has been efficiently used to inactivate therapeutic targets, oncogene products, and to induce viral resistance in plants. Ab fragments expressed in the appropriate cell compartment may also help to elucidate the functions of a protein of interest. We report in this study the successful targeting of the protein tyrosine kinase Syk in the RBL-2H3 rat basophilic leukemia cell line. We isolated from a phage display library human single-chain variable fragments (scFv) directed against the portion of Syk containing the Src homology 2 domains and the linker region that separates them. Among them, two scFv named G4G11 and G4E4 exhibited the best binding to Syk in vivo in a yeast two-hybrid selection system. Stable transfectants of RBL-2H3 cells expressing cytosolic G4G11 and G4E4 were established. Immunoprecipitation experiments showed that intracellular G4G11 and G4E4 bind to Syk, but do not inhibit the activation of Syk following FcεRI aggregation, suggesting that the scFv do not affect the recruitment of Syk to the receptor. Nevertheless, FcεRI-mediated calcium mobilization and the release of inflammatory mediators are inhibited, and are consistent with a defect in Bruton’s tyrosine kinase and phospholipase C-γ2 tyrosine phosphorylation and activation. Interestingly, FcεRI-induced mitogen-activated protein kinase phosphorylation is not altered, suggesting that intracellular G4G11 and G4E4 do not prevent the coupling of Syk to the Ras pathway, but they selectively inhibit the pathway involving phospholipase C-γ2 activation.
Expression of CD28 by Bone Marrow Stromal Cells and Its Involvement in B Lymphopoiesis
Authors: Gray Parkin Kirstin , Stephan Robert P. , Apilado Ron-Gran , Lill-Elghanian Deborah A. , Lee Kelvin P. , Saha Bhaskar , Witte Pamela L. 
Published: April 2014

AbstractYoung mice lacking CD28 have normal numbers of peripheral B cells; however, abnormalities exist in the humoral immune response that may result from an intrinsic defect in the B cells. The goal of this study was to assess whether CD28 could be involved in the development of B cells. CD28 mRNA was detected preferentially in the fraction of bone marrow enriched for stromal cells. Flow cytometry and RT-PCR analysis demonstrated that CD28 was also expressed by primary-cultured stromal cells that supported B lymphopoiesis. Confocal microscopy revealed that in the presence of B-lineage cells, CD28 was localized at the contact interface between B cell precursors and stromal cells. In addition, CD80 was detected on 2–6% of freshly isolated pro- and pre-B cells, and IL-7 stimulation led to induction of CD86 on 15–20% of pro- and pre-B cells. We also observed that stromal cell-dependent production of B-lineage cells in vitro was greater on stromal cells that lacked CD28. Finally, the frequencies of B-lineage precursors in the marrow from young (4- to 8-wk-old) CD28−/− mice were similar to those in wild-type mice; however, older CD28−/− mice (15–19 mo old) exhibited a 30% decrease in pro-B cells and a 50% decrease in pre-B cells vs age-matched controls. Our results suggest that CD28 on bone marrow stromal cells participates in stromal-dependent regulation of B-lineage cells in the bone marrow. The localization of CD28 at the stromal cell:B cell precursor interface suggests that molecules important for T cell:B cell interactions in the periphery may also participate in stromal cell:B cell precursor interactions in the bone marrow.
Suppressor of Cytokine Signaling 1 Inhibits Cytokine Induction of CD40 Expression in Macrophages
Authors: Wesemann Duane R. , Dong Yuanshu , O’Keefe George M. , Nguyen Vince T. , Benveniste Etty N. 
Published: April 2014

AbstractCD40 is a type I membrane-bound molecule belonging to the TNFR superfamily that is expressed on various immune cells including macrophages and microglia. The aberrant expression of CD40 is involved in the initiation and maintenance of various human diseases including multiple sclerosis, arthritis, atherosclerosis, and Alzheimer’s disease. Inhibition of CD40 signaling has been shown to provide a significant beneficial effect in a number of animal models of human diseases including the aforementioned examples. We have previously shown that IFN-γ induces CD40 expression in macrophages and microglia. IFN-γ leads to STAT-1α activation directly and up-regulation of NF-κB activity due to the secretion and subsequent autocrine signaling of TNF-α. However, TNF-α alone is not capable of inducing CD40 expression in these cells. Suppressor of cytokine signaling 1 protein (SOCS-1) is a cytokine-inducible Src homology 2-containing protein that regulates cytokine receptor signaling by inhibiting STAT-1α activation via a specific interaction with activated Janus kinase 2. Given the important role of CD40 in inflammatory events in the CNS as well as other organ systems, it is imperative to understand the molecular mechanisms contributing to both CD40 induction and repression. We show that ectopic expression of SOCS-1 abrogates IFN-γ-induced CD40 protein expression, mRNA levels, and promoter activity. Additionally, IFN-γ-induced TNF-α secretion, as well as STAT-1α and NF-κB activation, are inhibited in the presence of SOCS-1. We conclude that SOCS-1 inhibits cytokine-induced CD40 expression by blocking IFN-γ-mediated STAT-1α activation, which also then results in suppression of IFN-γ-induced TNF-α secretion and subsequent NF-κB activation.
NK T Cell Precursors Exhibit Differential Cytokine Regulation and Require Itk for Efficient Maturation
Authors: Gadue Paul , Stein Paul L. 
Published: April 2014

AbstractNK T cells are a lymphocyte lineage that is selected by CD1d and is characterized by the ability to rapidly secrete large amounts of both IFN-γ and IL-4 after TCR stimulation. Using reactivity to CD1d tetramers to define presumptive NK T cells, several NK T cell progenitor populations were characterized based upon NK marker expression and CD4 vs CD8 expression. The earliest populations were found to be negative for NK markers and could proliferate to IL-7, while mature NK T cells did not. The NK1.1− NK T cell progenitors were capable of up-regulating NK1.1 when transferred in vivo. Upon stimulation, the NK1.1− populations secrete IL-4, but little IFN-γ. As the cells mature and up-regulate NK1.1, they acquire the ability to secrete IFN-γ. Finally, the Tec family tyrosine kinase Itk is necessary for optimal NK1.1 up-regulation and hence final maturation of NK T cells. The itk−/− mice also display a progressive decrease in NK T cells in older animals, suggesting a further role in peripheral maintenance.
MultipleChlamydia pneumoniaeAntigens Prime CD8+ Tc1 Responses That Inhibit Intracellular Growth of This Vacuolar Pathogen
Authors: Wizel Benjamin , Starcher Barry C. , Samten Buka , Chroneos Zissis , Barnes Peter F. , Dzuris John , Higashimoto Yuichiro , Appella Ettore , Sette Alessandro 
Published: April 2014

AbstractCD8+ T cells play an essential role in immunity to Chlamydia pneumoniae (Cpn). However, the target Ags recognized by Cpn-specific CD8+ T cells have not been identified, and the mechanisms by which this T cell subset contributes to protection remain unknown. In this work we demonstrate that Cpn infection primes a pathogen-specific CD8+ T cell response in mice. Eighteen H-2b binding peptides representing sequences from 12 Cpn Ags sensitized target cells for MHC class I-restricted lysis by CD8+ CTL generated from the spleens and lungs of infected mice. Peptide-specific IFN-γ-secreting CD8+ T cells were present in local and systemic compartments after primary infection, and these cells expanded after pathogen re-exposure. CD8+ T cell lines to the 18 Cpn epitope-bearing peptides were cytotoxic, displayed a memory phenotype, and secreted IFN-γ and TNF-α, but not IL-4. These CTL lines lysed Cpn-infected macrophages, and the lytic activity was inhibited by brefeldin A, indicating endogenous processing of CTL Ags. Finally, Cpn peptide-specific CD8+ CTL suppressed chlamydial growth in vitro by direct lysis of infected cells and by secretion of IFN-γ and other soluble factors. These studies provide information on the mechanisms by which CD8+ CTL protect against Cpn, furnish the tools to investigate their possible role in immunopathology, and lay the foundation for future work to develop vaccines against acute and chronic Cpn infections.
Role of IL-12-Independent and IL-12-Dependent Pathways in Regulating Generation of the IFN-γ Component of T Cell Responses toSalmonella typhimurium
Authors: John Beena , Rajagopal Deepa , Pashine Achal , Rath Satyajit , George Anna , Bal Vineeta 
Published: April 2014

AbstractClearance of facultative intracellular pathogens such as Salmonella requires IFN-γ from CD4 T cells. Mechanisms linking intracellular pathogen recognition with induction of IFN-γ-producing T cells are still poorly understood. We show in this study that IL-12 is not required for commitment to the IFN-γ-producing T cell response in infection with Salmonella typhimurium, but is needed for its maintenance. The IL-12-independent signals required for commitment depend on events during the first hour of infection and are related to Ag presentation. Even transient attenuation of Ag presentation early during infection specifically abrogates the IFN-γ component of the resulting CD4 T cell response. The IL-12 needed for maintenance is also better induced by live rather than dead bacteria in vivo, and this difference is due to specific suppression of IL-12 induction by dead bacteria. Presence of exogenous IL-4 down-modulates IL-12 production by macrophages activated in vitro. Furthermore, macrophages from IL-4-null mice secrete high levels of both IL-12 and IL-18 in response to stimulation in vivo even with dead bacteria, but this does not lead to induction of IFN-γ-secreting T cells in response to immunization with dead S. typhimurium. Early IL-4 is contributed by triggering of CD4 NK T cells by dead, but not live, bacteria. Thus, Ag presentation-related IL-12-independent events and IL-4-sensitive IL-12-dependent events play crucial complementary roles in the generation of the IFN-γ-committed CD4 T cell component of the immune response in Salmonella infection.
Activation of Peroxisome Proliferator-Activated Receptor γ by Nitric Oxide in Monocytes/Macrophages Down-Regulates p47phox and Attenuates the Respiratory Burst
Authors: von Knethen Andreas , Brüne Bernhard 
Published: April 2014

Abstract
NO appears as an important determinant in auto and paracrine macrophage function. We hypothesized that NO switches monocyte/macrophage function from a pro- to an anti-inflammatory phenotype by activating anti-inflammatory properties of the peroxisome proliferator-activated receptor (PPAR)γ. NO-releasing compounds (100 μM S-nitrosoglutathione or 50 μM spermine-NONOate) as well as inducible NO synthase induction provoked activation of PPARγ. This was proven by EMSAs, with the notion that supershift analysis pointed to the involvement of PPARγ. PCR analysis ruled out induction of PPARγ mRNA as a result of NO supplementation. Reporter assays, with a construct containing a triple PPAR response element in front of a thymidine kinase minimal promoter driving the luciferase gene, were positive in response to NO delivery. DNA binding capacity as well as the transactivating capability of PPARγ were attenuated by addition of the antioxidant N-acetyl-cysteine or in the presence of the NO scavenger 2-phenyl-4,4,5,6-tetramethyl-imidazoline-1-oxyl 3-oxide. Having established that NO but not lipophilic cyclic GMP analogs activated PPARγ, we verified potential anti-inflammatory consequences. The oxidative burst of macrophages, evoked by phorbol ester, was attenuated in association with NO-elicited PPARγ activation. A cause-effect relationship was demonstrated when PPAR response element decoy oligonucleotides, supplied in front of NO delivery, allowed to regain an oxidative response. PPARγ-mediated down-regulation of p47 phagocyte oxidase, a component of the NAD(P)H oxidase system, was identified as one molecular mechanism causing inhibition of superoxide radical formation. We conclude that NO participates in controlling the pro- vs anti-inflammatory phenotype of macrophages by modulating PPARγ.
Targeting the Function of IFN-γ-Inducible Protein 10 Suppresses Ongoing Adjuvant Arthritis
Authors: Salomon Izhar , Netzer Nir , Wildbaum Gizi , Schif-Zuck Sagie , Maor Gila , Karin Nathan 
Published: April 2014

AbstractIFN-γ-inducible protein 10 (IP-10) is a CXC chemokine that is thought to manifest a proinflammatory role because it stimulates the directional migration of activated T cells, particularly Th1 cells. It is an open question whether this chemokine is also directly involved in T cell polarization. We show here that during the course of adjuvant-induced arthritis the immune system mounts a notable Ab titer against self-IP-10. Upon the administration of naked DNA encoding IP-10, this titer rapidly accelerates to provide protective immunity. Self-specific Ab to IP-10 developed in protected animals, as well as neutralizing Ab to IP-10 that we have generated in rabbits, could inhibit leukocyte migration, alter the in vivo and in vitro Th1/Th2 balance toward low IFN-γ, low TNF-α, high IL-4-producing T cells, and adoptively transfer disease suppression. This not only demonstrates the pivotal role of this chemokine in T cell polarization during experimentally induced arthritis but also suggests a practical way to interfere in the regulation of disease to provide protective immunity. From the basic science perspective, this study challenges the paradigm of in vivo redundancy. After all, we did not neutralize the activity of other chemokines that bind CXCR3 (i.e., macrophage-induced gene and IFN-inducible T cell α chemoattractant) and yet significantly blocked not only adjuvant-induced arthritis but also the in vivo competence to mount delayed-type hypersensitivity.
The Major Murine Systemic Lupus Erythematosus Susceptibility LocusSle1Results in Abnormal Functions of Both B and T Cells
Authors: Sobel Eric S. , Satoh Minoru , Chen Yifang , Wakeland Edward K. , Morel Laurence 
Published: April 2014

AbstractSle1 is a major susceptibility locus in the NZM2410 murine model of systemic lupus erythematosus. When isolated on a C57BL/6 background in the B6.Sle1 congenic strain, Sle1 results in the production of high levels of anti-chromatin IgG Abs, histone-specific T cells, and increased B and T cell activation. We have shown by mixed bone marrow chimeras with allotypic markers that Sle1 is expressed in B cells. Using the same technique, we now show that it is also expressed in T cells. To assess whether Sle1 results in intrinsic defects in B or T cells, we have bred the μMT and Tcrα−/− mutations onto B6.Sle1 resulting in the absence of circulating B cells and αβ T cells in B6.Sle1.μMT and B6.Sle1.Tcrα−/−, respectively. The immune phenotypes in these two strains were compared with that of B6.Sle1 and B6.μMT or B6.Tcrα−/−. Sle1-expressing B cells broke tolerance to chromatin in the absence of T cells, as shown by high levels of anti-ssDNA IgM Abs in B6.Sle1.Tcrα−/− mice, and had an increased expression of activation markers. Conversely, increased expression of activation markers and increased cytokine production were observed in Sle1-expressing T cells in the absence of B cells in B6.Sle1.μMT mice. However, the production of IgG antinuclear Abs required the presence of both T and B cells. These experiments showed that Sle1 expression results in both B and T cells intrinsic defects and demonstrate that the documented involvement of each cell compartment in the production of anti-chromatin Abs corresponds to genetic defects rather than bystander effects.