bluuebunny/crossref_metadata_2025 huggingface dataset:
Distinct Footprints of TCR Engagement with Highly Homologous Ligands
Authors: Santori Fabio R. , Holmberg Kaisa , Ostrov David , Gascoigne Nicholas R. J. , Vukmanović Stanislav
Published: April 2014

T cell receptor engagement promotes proliferation, differentiation, survival, or death of T lymphocytes. The affinity/avidity of the TCR ligand and the maturational stage of the T cell are thought to be principal determinants of the outcome of TCR engagement. We demonstrate in this study that the same mouse TCR preferentially uses distinct residues of homologous peptides presented by the MHC molecules to promote specific cellular responses. The preference for distinct TCR contacts depends on neither the affinity/avidity of TCR engagement (except in the most extreme ranges), nor the maturity of engaged T cells. Thus, different portions of the TCR ligand appear capable of biasing T cells toward specific biological responses. These findings explain differences in functional versatility of TCR ligands, as well as anomalies in the relationship between affinity/avidity of the TCR for the peptide/MHC and cellular responses of T cells.
Coupling In Silico and In Vitro Analysis of Peptide-MHC Binding: A Bioinformatic Approach Enabling Prediction of Superbinding Peptides and Anchorless Epitopes
Authors: Doytchinova Irini A. , Walshe Valerie A. , Jones Nicola A. , Gloster Simone E. , Borrow Persephone , Flower Darren R.
Published: April 2014

The ability to define and manipulate the interaction of peptides with MHC molecules has immense immunological utility, with applications in epitope identification, vaccine design, and immunomodulation. However, the methods currently available for prediction of peptide-MHC binding are far from ideal. We recently described the application of a bioinformatic prediction method based on quantitative structure-affinity relationship methods to peptide-MHC binding. In this study we demonstrate the predictivity and utility of this approach. We determined the binding affinities of a set of 90 nonamer peptides for the MHC class I allele HLA-A*0201 using an in-house, FACS-based, MHC stabilization assay, and from these data we derived an additive quantitative structure-affinity relationship model for peptide interaction with the HLA-A*0201 molecule. Using this model we then designed a series of high affinity HLA-A2-binding peptides. Experimental analysis revealed that all these peptides showed high binding affinities to the HLA-A*0201 molecule, significantly higher than the highest previously recorded. In addition, by the use of systematic substitution at principal anchor positions 2 and 9, we showed that high binding peptides are tolerant to a wide range of nonpreferred amino acids. Our results support a model in which the affinity of peptide binding to MHC is determined by the interactions of amino acids at multiple positions with the MHC molecule and may be enhanced by enthalpic cooperativity between these component interactions.
The CD40-Induced Signaling Pathway in Endothelial Cells Resulting in the Overexpression of Vascular Endothelial Growth Factor Involves Ras and Phosphatidylinositol 3-Kinase
Authors: Flaxenburg Jesse A. , Melter Michael , Lapchak Peter H. , Briscoe David M. , Pal Soumitro
Published: April 2014

Ligation of endothelial cell (EC) CD40 induces the expression of several proinflammatory cytokines as well as angiogenesis factors, including vascular endothelial growth factor (VEGF). Moreover, despite the reported importance of CD40 in cell-mediated immunity, little is known of the CD40-induced signaling pathways in EC. In this study, we have investigated the function of the Ras signaling pathway(s) for CD40-induced overexpression of VEGF. EC were transiently transfected with a full-length VEGF promoter-luciferase construct and a dominant-inhibitory mutant of Ras (Ras17N). Following transfection, ligation of CD40 with soluble CD40 ligand resulted in a significant increase in VEGF transcriptional activation, and the inhibitory mutant of Ras blocked this CD40-induced VEGF overexpression. Using EMSA and Western blot analysis, we demonstrated that CD40-dependent binding of nuclear protein(s) to the VEGF promoter and CD40-induced VEGF protein expression in EC were also inhibited by the Ras mutant. Immunoprecipitation studies revealed that ligation of CD40 on EC promoted an increased association of Ras with its effector molecules Raf, Rho, and phosphatidylinositol 3-kinase (PI3K). But, cotransfection of effector-loop mutants of Ras determined that only PI3K was functional for Ras-induced VEGF transcription. Also, wortmanin and a dominant-inhibitory mutant of PI3K inhibited CD40-induced overexpression of VEGF. Together these findings demonstrate that both Ras and PI3K are intermediaries in CD40-induced regulation of VEGF in EC. We believe our findings are of importance in several chronic inflammatory diseases, including atherosclerosis and allograft rejection associated with both CD40-CD40 ligand signaling as well as VEGF expression and function.
Characterization of a Peptide Inhibitor of Janus Kinase 2 That Mimics Suppressor of Cytokine Signaling 1 Function
Authors: Flowers Lawrence O. , Johnson Howard M. , Mujtaba Mustafa G. , Ellis Morgan R. , Haider S. Mohammed I. , Subramaniam Prem S.
Published: April 2014

Positive and negative regulation of cytokines such as IFN-γ are key to normal homeostatic function. Negative regulation of IFN-γ in cells occurs via proteins called suppressors of cytokine signaling (SOCS)1 and -3. SOCS-1 inhibits IFN-γ function by binding to the autophosphorylation site of the tyrosine kinase Janus kinase (JAK)2. We have developed a short 12-mer peptide, WLVFFVIFYFFR, that binds to the autophosphorylation site of JAK2, resulting in inhibition of its autophosphorylation as well as its phosphorylation of IFN-γ receptor subunit IFNGR-1. The JAK2 tyrosine kinase inhibitor peptide (Tkip) did not bind to or inhibit tyrosine autophosphorylation of vascular endothelial growth factor receptor or phosphorylation of a substrate peptide by the protooncogene tyrosine kinase c-src. Tkip also inhibited epidermal growth factor receptor autophosphorylation, consistent with the fact that epidermal growth factor receptor is regulated by SOCS-1 and SOCS-3, similar to JAK2. Although Tkip binds to unphosphorylated JAK2 autophosphorylation site peptide, it binds significantly better to tyrosine-1007 phosphorylated JAK2 autophosphorylation site peptide. SOCS-1 only recognizes the JAK2 site in its phosphorylated state. Thus, Tkip recognizes the JAK2 autophosphorylation site similar to SOCS-1, but not precisely the same way. Consistent with inhibition of JAK2, Tkip inhibited the ability of IFN-γ to induce an antiviral state as well as up-regulate MHC class I molecules on cells at a concentration of ∼10 μM. This is similar to the Kd of SOCS-3 for the erythropoietin receptor. These data represent a proof-of-concept demonstration of a peptide mimetic of SOCS-1 that regulates JAK2 tyrosine kinase function.
Enhancer-Mediated Control of Macrophage-Specific Arginase I Expression
Authors: Pauleau Anne-Laure , Rutschman Robert , Lang Roland , Pernis Alessandra , Watowich Stephanie S. , Murray Peter J.
Published: April 2014

Arginase I expression in the liver must remain constant throughout life to eliminate excess nitrogen via the urea cycle. In contrast, arginase I expression in macrophages is silent until signals from Th2 cytokines such as IL-4 and IL-13 are received and the mRNA is then induced four to five orders of magnitude. Arginase I is hypothesized to play a regulatory and potentially pathogenic role in diseases such as asthma, parasitic, bacterial, and worm infections by modulating NO levels and promoting fibrosis. We show that Th2-inducible arginase I expression in mouse macrophages is controlled by an enhancer that lies −3 kb from the basal promoter. PU.1, IL-4-induced STAT6, and C/EBPβ assemble at the enhancer and await the effect of another STAT6-regulated protein(s) that must be synthesized de novo. Identification of a powerful extrahepatic regulatory enhancer for arginase I provides potential to manipulate arginase I activity in immune cells while sparing liver urea cycle function.
Pulmonary Collectins Enhance Phagocytosis of Mycobacterium avium through Increased Activity of Mannose Receptor
Authors: Kudo Kazumi , Sano Hitomi , Takahashi Hiroki , Kuronuma Koji , Yokota Shin-ichi , Fujii Nobuhiro , Shimada Ken-ichi , Yano Ikuya , Kumazawa Yoshio , Voelker Dennis R. , Abe Shosaku , Kuroki Yoshio
Published: April 2014

Collectins, including surfactant proteins A (SP-A) and D (SP-D) and mannose binding lectin (MBL), are the important constituents of the innate immune system. Mycobacterium avium, a facultative intracellular pathogen, has developed numerous mechanisms for entering mononuclear phagocytes. In this study, we investigated the interactions of collectins with M. avium and the effects of these lectins on phagocytosis of M. avium by macrophages. SP-A, SP-D, and MBL exhibited a concentration-dependent binding to M. avium. The binding of SP-A to M. avium was Ca2+-dependent but that of SP-D and MBL was Ca2+-independent. SP-A and SP-D but not MBL enhanced the phagocytosis of FITC-labeled M. avium by rat alveolar macrophages and human monocyte-derived macrophages. Excess mannan, zymosan, and lipoarabinomannan derived from the M. avium-intracellular complex, significantly decreased the collectin-stimulated phagocytosis of M. avium. Enhanced phagocytosis was not affected by the presence of cycloheximide or chelation of Ca2+. The mutated collectin, SP-AE195Q, R197D exhibited decreased binding to M. avium but stimulated phagocytosis to a level comparable to wild-type SP-A. Enhanced phagocytosis by cells persisted even after preincubation and removal of SP-A or SP-D. Rat alveolar macrophages that had been incubated with SP-A or SP-D also exhibited enhanced uptake of 125I-mannosylated BSA. Analysis by confocal microscopy and flow cytometry revealed that the lung collectins up-regulated the cell surface expression of mannose receptor on monocyte-derived macrophages. These results provide compelling evidence that SP-A and SP-D enhance mannose receptor-mediated phagocytosis of M. avium by macrophages.
IL-10 Is an Important Mediator of the Enhanced Susceptibility to Pneumococcal Pneumonia after Influenza Infection
Authors: van der Sluijs Koenraad F. , van Elden Leontine J. R. , Nijhuis Monique , Schuurman Rob , Pater Jennie M. , Florquin Sandrine , Goldman Michel , Jansen Henk M. , Lutter René , van der Poll Tom
Published: April 2014

Secondary pneumococcal pneumonia is a serious complication during and shortly after influenza infection. We established a mouse model to study postinfluenza pneumococcal pneumonia and evaluated the role of IL-10 in host defense against Streptococcus pneumoniae after recovery from influenza infection. C57BL/6 mice were intranasally inoculated with 10 median tissue culture infective doses of influenza A (A/PR/8/34) or PBS (control) on day 0. By day 14 mice had regained their normal body weight and had cleared influenza virus from the lungs, as determined by real-time quantitative PCR. On day 14 after viral infection, mice received 104 CFU of S. pneumoniae (serotype 3) intranasally. Mice recovered from influenza infection were highly susceptible to subsequent pneumococcal pneumonia, as reflected by a 100% lethality on day 3 after bacterial infection, whereas control mice showed 17% lethality on day 3 and 83% lethality on day 6 after pneumococcal infection. Furthermore, 1000-fold higher bacterial counts at 48 h after infection with S. pneumoniae and, particularly, 50-fold higher pulmonary levels of IL-10 were observed in influenza-recovered mice than in control mice. Treatment with an anti-IL-10 mAb 1 h before bacterial inoculation resulted in reduced bacterial outgrowth and markedly reduced lethality during secondary bacterial pneumonia compared with those in IgG1 control mice. In conclusion, mild self-limiting influenza A infection renders normal immunocompetent mice highly susceptible to pneumococcal pneumonia. This increased susceptibility to secondary bacterial pneumonia is at least in part caused by excessive IL-10 production and reduced neutrophil function in the lungs.
Accumulation of γδ T Cells in the Lungs and Their Regulatory Roles in Th1 Response and Host Defense against Pulmonary Infection with Cryptococcus neoformans
Authors: Uezu Kaori , Kawakami Kazuyoshi , Miyagi Kazuya , Kinjo Yuki , Kinjo Takeshi , Ishikawa Hiromichi , Saito Atsushi
Published: April 2014

The present study was designed to elucidate the role of γδ T cells in the host defense against pulmonary infection with Cryptococcus neoformans. The γδ T cells in lungs commenced to increase on day 1, reached a peak level on day 3 or 6, and then decreased on day 10 after intratracheal infection. The increase of these cells was similar in monocyte chemoattractant protein (MCP)-1-deficient mice, although that of NK and NKT cells was significantly reduced. The number of live microorganisms in lungs on days 14 and 21 was significantly reduced in mice depleted of γδ T cells by a specific mAb compared with mice treated with control IgG. Similarly, elimination of this fungal pathogen was promoted in γδ T cell-deficient (TCR-δ−/−) mice compared with control littermate mice. Finally, lung and serum levels of IFN-γ on days 7 and 14 and on day 7 postinfection, respectively, were significantly higher in TCR-δ−/− mice than in littermate mice, whereas levels of TGF-β showed the opposite results. IL-4 and IL-10 were not different between these mice. IFN-γ production by draining lymph node cells upon restimulation with cryptococcal Ags was significantly higher in the infected TCR-δ−/− mice than in control mice. Our results demonstrated that γδ T cells accumulated in the lungs in a manner different from NK and NKT cells after cryptococcal infection and played a down-modulatory role in the development of Th1 response and host resistance against this fungal pathogen.
Differential Regulation of TNF-R1 Signaling: Lipid Raft Dependency of p42mapk/erk2 Activation, but Not NF-κB Activation
Authors: Doan Joyce E. S. , Windmiller David A. , Riches David W. H.
Published: April 2014

The TNFR, TNF-R1, is localized to lipid raft and nonraft regions of the plasma membrane. Ligand binding sets in motion signaling cascades that promote the activation of p42mapk/erk2 and NF-κB. However, the role of receptor localization in the activation of downstream signaling events is poorly understood. In this study, we investigated the dynamics of TNF-R1 localization to lipid rafts and the consequences of raft localization on the activation of p42mapk/erk2 and NF-κB in primary cultures of mouse macrophages. Using sucrose density gradient ultracentrifugation and a sensitive ELISA to detect TNF-R1, we show that TNF-R1 is rapidly and transiently recruited to lipid rafts in response to TNF-α. Disruption of lipid rafts by cholesterol depletion prevented the TNF-α-dependent recruitment of TNF-R1 to lipid rafts and inhibited the activation of p42mapk/erk2, while the activation of NF-κB was unaffected. In addition, phosphorylated p42mapk/erk2, but not receptor interacting protein, I-κB kinase-γ, or I-κBα was detected in raft-containing fractions following TNF-α stimulation. These findings suggest that TNF-R1 is localized to both lipid raft and nonraft regions of the plasma membrane and that each compartment is capable of initiating different signaling responses. We propose that segregation of TNF-R1 to raft and nonraft regions of the plasma membrane contributes to the diversity of signaling responses initiated by TNF-R1.
An Annexin 1 N-Terminal Peptide Activates Leukocytes by Triggering Different Members of the Formyl Peptide Receptor Family
Authors: Ernst Stefanie , Lange Carsten , Wilbers Andreas , Goebeler Verena , Gerke Volker , Rescher Ursula
Published: April 2014

The human N-formyl peptide receptor (FPR) is a key modulator of chemotaxis directing granulocytes toward sites of bacterial infections. FPR is the founding member of a subfamily of G protein-coupled receptors thought to function in inflammatory processes. The other two members, FPR-like (FPRL)1 and FPRL2, have a greatly reduced affinity for bacterial peptides or do not bind them at all, with FPRL2 being considered an orphan receptor so far. In this study we show that a peptide derived from the N-terminal domain of the anti-inflammatory protein annexin 1 (lipocortin 1) can activate all three FPR family members at similar concentrations. The annexin 1 peptide initiates chemotactic responses in human monocytes that express all three FPR family members and also desensitizes the cells toward subsequent stimulation with bacterial peptide agonists. Experiments using HEK 293 cells stably expressing a single FPR family member reveal that all three receptors can be activated and desensitized by the N-terminal annexin 1 peptide. These observations identify the annexin 1 peptide as the first endogenous ligand of FPRL2 and indicate that annexin 1 participates in regulating leukocyte emigration into inflamed tissue by activating and desensitizing different receptors of the FPR family.
15-Deoxy-Δ12,14-Prostaglandin J2 Inhibits Glucocorticoid Binding and Signaling in Macrophages through a Peroxisome Proliferator-Activated Receptor γ-Independent Process
Authors: Cheron Adeline , Peltier Julie , Perez Joëlle , Bellocq Agnès , Fouqueray Bruno , Baud Laurent
Published: April 2014

15-Deoxy-Δ12,14-PGJ2 (15d-PGJ2) is involved in the control of inflammatory reaction. We tested the hypothesis that 15d-PGJ2 would exert this control in part by modulating the sensitivity of inflammatory cells to glucocorticoids. Human U937cells and mouse RAW 264.7 cells were exposed to 15d-PGJ2, and binding experiments were performed with [3H]dexamethasone as a glucocorticoid receptor (GR) ligand. 15d-PGJ2 caused a transient and concentration-dependent decrease in [3H]dexamethasone-specific binding to either cells through a decrease in the number of GR per cell without significant modification of the Kd value. These changes were related to functional alteration of the GR rather than to a decrease in GR protein. They did not require the engagement of peroxisome proliferator-activated receptor γ (PPARγ), because the response to 15d-PGJ2 was neither mimicked by the PPARγ agonist ciglitazone nor prevented by the PPARγ antagonist bisphenol A diglycidyl ether. 15d-PGJ2 altered GR possibly through the interaction of its cyclopentenone ring with GR cysteine residues because the cyclopentenone ring per se could mimic the effect of 15d-PGJ2, and modification of GR cysteine residues with methyl methanethiosulfonate suppressed the response to 15d-PGJ2. Finally, 15d-PGJ2-induced decreases in glucocorticoid binding to GR resulted in parallel decreases in the ability of GR to activate the transcription of a glucocorticoid-inducible reporter gene and to reduce the expression of monocyte chemoattractant protein-1. Together these data suggest that 15d-PGJ2 limits glucocorticoid binding and signaling in monocytes/macrophages through a PPARγ-independent and cyclopentenone-dependent mechanism. It provides a way in which 15d-PGJ2 would exert proinflammatory activities in addition to its known anti-inflammatory activities.
Staging the Initiation of Autoantibody-Induced Arthritis: A Critical Role for Immune Complexes
Authors: Wipke Brian T. , Wang Zheng , Nagengast Wouter , Reichert David E. , Allen Paul M.
Published: April 2014

In the K/B×N mouse model of arthritis, autoantibodies against glucose-6-phosphate isomerase cause joint-specific inflammation and destruction. We have shown using micro-positron emission tomography that these glucose-6-phosphate isomerase-specific autoantibodies rapidly localize to distal joints of mice. In this study we used micro-positron emission tomography to delineate the stages involved in the development of arthritis. Localization of Abs to the joints depended upon mast cells, neutrophils, and FcRs, but not on C5. Surprisingly, anti-type II collagen Abs alone did not accumulate in the distal joints, but could be induced to do so by coinjection of irrelevant preformed immune complexes. Control Abs localized to the joint in a similar manner. Thus, immune complexes are essential initiators of arthritis by sequential activation of neutrophils and mast cells to allow Abs access to the joints, where they must bind a target Ag to initiate inflammation. Our findings support a four-stage model for the development of arthritis and identify checkpoints where the disease is reversible.
Stat3 Activation in Acute Lung Injury
Authors: Gao Hongwei , Guo Ren-Feng , Speyer Cecilia L. , Reuben Jayne , Neff Thomas A. , Hoesel L. Marco , Riedemann Niels C. , McClintock Shannon D. , Sarma J. Vidya , Van Rooijen Nico , Zetoune Firas S. , Ward Peter A.
Published: April 2014

Stat3 plays diverse roles in biological processes including cell proliferation, survival, apoptosis, and inflammation. Very little is known regarding its activation and function in the lung during acute inflammation. We now show that Stat3 activation was triggered in lungs and in alveolar macrophages after intrapulmonary deposition of IgG immune complexes in rats. Low levels of constitutive Stat3 were observed in normal rat lungs as determined by the EMSA. Stat3 activity in whole lung extracts increased 2 h after initiation of IgG immune complex deposition, reaching maximal levels by 4 h, whereas Stat3 activation was found in alveolar macrophages as early as 30 min after onset of injury. Expression and activation of Stat3 mRNA, protein, and protein phosphorylation was accompanied by increased gene expression of IL-6, IL-10, and suppressor of cytokine signaling-3 in whole lung tissues. Both Tyr705 and Ser727 phosphorylation were involved in Stat3 activation as assessed in whole lung extracts. C5a (complement 5, fragment a) per se can induce phosphorylation of Ser727 of Stat3. In vivo, Stat3 activation was dramatically suppressed by depletion of neutrophils or lung macrophages, resulting in reduced gene expression of IL-6 and IL-10 in whole lung tissues. Using blocking Abs to IL-6, IL-10, and C5a, Stat3 activation induced by IgG immune complexes was markedly diminished. These data suggest in the lung injury model used that activation of Stat3 in lungs is macrophage dependent and neutrophil dependent. IL-6, IL-10, and C5a contribute to Stat3 activation in inflamed rat lung.
IL-1β Impairs Insulin-Like Growth Factor I-Induced Differentiation and Downstream Activation Signals of the Insulin-Like Growth Factor I Receptor in Myoblasts
Authors: Broussard Suzanne R. , McCusker Robert H. , Novakofski Jan E. , Strle Klemen , Shen Wen Hong , Johnson Rodney W. , Dantzer Robert , Kelley Keith W.
Published: April 2014

Proinflammatory cytokines are elevated in disorders characterized by muscle wasting and weakness, such as inflammatory myopathies and AIDS wasting. We recently demonstrated that TNF-α impairs the ability of insulin-like growth factor (IGF)-I to promote protein synthesis in muscle precursor cells. In this study we extend these findings by showing that low concentrations of IL-1β impair IGF-I-dependent differentiation of myoblasts, as assessed by expression of the muscle specific protein, myosin heavy chain. In the absence of exogenous IGF-I, IL-1β (1 ng/ml) did not impair muscle cell development. However, in the presence of IGF-I, 100-fold lower concentrations of IL-1β (0.01 ng/ml) significantly suppressed myoblast differentiation, protein synthesis, and myogenin expression. Increasing IL-1β to 1 ng/ml completely blocked the anabolic actions of IGF-I in murine C2C12 myoblasts. Similarly, IL-1β inhibited IGF-I-stimulated protein synthesis in primary porcine myoblasts. IL-1β impaired the actions of IGF-I at a point distal to the IGF receptor, and this was not due to IL-1β-induced cell death. Instead, IL-1β inhibited the ability of IGF-I to phosphorylate tyrosine residues on both of its downstream docking proteins, insulin receptor substrate 1 and insulin receptor substrate 2. These data establish that physiological concentrations of IL-1β block the ability of IGF-I to promote protein synthesis, leading to reduced expression of the myogenic transcription factor, myogenin, and the subsequent development of more mature differentiated cells that express myosin heavy chain. Collectively, the results are consistent with the notion that very low concentrations of IL-1β significantly impair myogenesis, but they are unable to do so in the absence of the growth factor IGF-I.
Basophils Infiltrate Human Gastric Mucosa at Sites of Helicobacter pylori Infection, and Exhibit Chemotaxis in Response to H. pylori-derived Peptide Hp(2–20)
Authors: de Paulis Amato , Prevete Nella , Fiorentino Isabella , Walls Andrew F. , Curto Monica , Petraroli Angelica , Castaldo Vincenza , Ceppa Paola , Fiocca Roberto , Marone Gianni
Published: April 2014

Basophils, which are normally confined to the circulation, can migrate to sites of allergic inflammation. Using the specific mAb, BB1, we detected basophil infiltration of the gastric mucosa of Helicobacter pylori-infected patients affected by moderate and severe gastritis. Basophils were not found in H. pylori-free individuals or in subjects with mild gastritis. The H. pylori-derived peptide, Hp(2–20), was a potent basophil chemoattractant in vitro, whereas the control peptide, Hp1, was ineffective. Basophils from peripheral blood of healthy volunteers expressed mRNA for the formyl peptide receptors, N-formyl-peptide receptor (FPR), FPR-like (FPRL)1, and FPRL2. Preincubation of basophils with FMLP or Hp(2–20) caused complete desensitization to a subsequent challenge with homologous stimulus. Incubation of basophils with a low concentration of FMLP, which binds with high affinity to FPR, but not to FPRL1 or FPRL2, did not affect the chemotactic response to Hp(2–20). In contrast, a high concentration of FMLP, which binds to FPRL1 and FPRL2, reduced the chemotactic response to Hp(2–20). The FPR antagonist, cyclosporin H, prevented chemotaxis induced by FMLP, but not by Hp(2–20). Hp(2–20) could be responsible, at least in part, for basophil infiltration of the gastric mucosa of H. pylori-infected patients presumably through the interaction with FPRL1 and FPRL2.
Down-Regulation of IL-2 Production in T Lymphocytes by Phosphorylated Protein Kinase A-RIIβ
Authors: Elliott Michael R. , Shanks Ryan A. , Khan Islam U. , Brooks James W. , Burkett Pamela J. , Nelson Brandy J. , Kyttaris Vasileios , Juang Yuang-Taung , Tsokos George C. , Kammer Gary M.
Published: April 2014

The β isoform of the type II regulatory subunit (RIIβ) of protein kinase A suppresses CREB transcriptional activity and c-Fos production in T cells following activation via the TCR. Because CREB is an integral nuclear transcription factor for IL-2 production by T cells, we tested the hypothesis that RIIβ down-regulates IL-2 expression and IL-2 production in T cells. Stable transfection of RIIβ in Jurkat T cells led to an ∼90% reduction in IL-2 mRNA and IL-2 protein following T cell activation. The inhibition of IL-2 production was associated with phosphorylation of the RIIβ subunit at serine 114 (pRIIβ) and localization of pRIIβ in intranuclear clusters. A serine 114 phosphorylation-defective mutant, RIIβS114A, did not form these intranuclear clusters as well as wild-type RIIβ, and did not inhibit IL-2 mRNA and protein synthesis, indicating that serine 114 phosphorylation is required for both nuclear localization and down-regulation of IL-2 production by RIIβ. In contrast to its effect on IL-2, RIIβ induced constitutive up-regulation of CD154 mRNA and cell surface expression. Thus, pRIIβ differentially regulates gene expression following T cell activation. Unexpectedly, we also found that stable overexpression of another protein kinase A regulatory subunit, RIα, had the opposite effect on IL-2 expression, causing a 3- to 4-fold increase in IL-2 production following stimulation. In summary, our data demonstrate a novel mechanism by which serine 114 phosphorylation and nuclear localization of RIIβ controls the regulation of gene expression in T cells.
The Allograft Defines the Type of Rejection (Acute versus Chronic) in the Face of an Established Effector Immune Response
Authors: Chalasani Geetha , Li Qi , Konieczny Bogumila T. , Smith-Diggs Lonnette , Wrobel Barbara , Dai Zhenhua , Perkins David L. , Baddoura Fady K. , Lakkis Fadi G.
Published: April 2014

Transplanted organs fail due to either acute or chronic rejection. The prevailing view is that the nature or magnitude of the recipient’s immune response to donor Ags determines the type of rejection. In variance with this view, we show in this study that the status of the graft itself plays a dominant role in defining the type of rejection even in the face of an established alloimmune response. Using adoptive transfer mouse models in which the graft is exposed to a constant number of effector lymphocytes, we found that newly transplanted heart allografts are rejected acutely, while healed-in allografts undergo chronic rejection. Acute rejection of healed-in allografts was largely recapitulated by subjecting the grafts to ischemia-reperfusion injury similar to that present in newly transplanted organs. Ischemia-Reperfusion injury altered the outcome of rejection by enhancing the accumulation of effector T cells within the graft. The accumulation of effector T cells in the graft was dependent on the presence of both ischemia-reperfusion injury (inflammation) and alloantigens. These findings demonstrate that the graft plays a dominant role in shaping the outcome of rejection by controlling the trafficking of effector T cells.
Altered p38 Mitogen-Activated Protein Kinase Expression in Different Leukocytes with Increment of Immunosuppressive Mediators in Patients with Severe Acute Respiratory Syndrome
Authors: Lee Chen-Hsiang , Chen Rong-Fu , Liu Jien-Wei , Yeh Wen-Tien , Chang Jen-Chieh , Liu Po-Mai , Eng Hock-Liew , Lin Meng-Chih , Yang Kuender D.
Published: April 2014

Severe acute respiratory syndrome (SARS) has spread to a global pandemic, especially in Asia. The transmission route of SARS has been clarified, but the immunopathogenesis of SARS is unclear. In an age-matched case-control design, we studied immune parameters in 15 SARS patients who were previously healthy. Plasma was harvested for detection of virus load, cytokines, and nitrite/nitrate levels, and blood leukocytes were subjected to flow cytometric analysis of intracellular mitogen-activated protein kinases (MAPKs) in different leukocytes. Patients with SARS had significantly higher IL-8 levels (p = 0.016) in early stage, and higher IL-2 levels (p = 0.039) in late stage than normal controls. Blood TNF-α, IL-6, and IL-10, and nitrite/nitrate levels were not significantly elevated. In contrast, TGF-β and PGE2 levels were significantly elevated in SARS patients. Five of the 15 SARS patients had detectable coronaviruses in blood, but patients with detectable and undetectable viremia had no different profiles of immune mediators. Flow cytometric analysis of MAPKs activation by phospho-p38 and phospho-p44/42 (extracellular signal-regulated kinase) expression showed that augmented p38 activation (p = 0.044) of CD14 monocytes associated with suppressed p38 activation (p = 0.033) of CD8 lymphocytes was found in SARS patients. These results suggest that regulation of TGF-β and PGE2 production and MAPKs activation in different leukocytes may be considered while developing therapeutics for the SARS treatment.
The Fourth Way? Harnessing Aggressive Tendencies in the Thymus
Authors: Baldwin Troy A. , Hogquist Kristin A. , Jameson Stephen C.
Published: April 2014

During late stages of thymic development, T cells must chose between different fates, dictated by their TCR specificity. Typically, this is thought of as a choice between three alternatives (being positive selection for useful T cells vs negative selection or neglect for harmful or useless T cells). However, there is growing evidence for a fourth alternative, in which T cells are positively selected by agonist ligands, which would normally be expected to induce T cell deletion. In this review, we will discuss where and when agonist selection is induced and whether this should be considered as a novel form of thymic selection or as an alternative differentiation state for Ag-exposed T cells.
Cutting Edge: TGF-β Signaling Is Required for the In Vivo Expansion and Immunosuppressive Capacity of Regulatory CD4+CD25+ T Cells
Authors: Huber Samuel , Schramm Christoph , Lehr Hans A. , Mann Amrit , Schmitt Steffen , Becker Christoph , Protschka Martina , Galle Peter R. , Neurath Markus F. , Blessing Manfred
Published: April 2014

Data regarding the role of TGF-β for the in vivo function of regulatory CD4+CD25+ T cells (Treg) are controversial. A transgenic mouse model with impaired TGF-β signaling specifically in T cells was used to assess the role of endogenous TGF-β for the in vivo function of CD4+CD25+ Treg in a murine model of colitis induced by dextran sulfate. Transfer of wild-type, but not transgenic CD4+CD25+ Treg was found to suppress colitis in wild-type mice. In addition, by transferring CFSE-labeled CD4+CD25+ Treg we could demonstrate that endogenous TGF-β promotes the expansion of CD4+CD25+ Treg in vivo. Transgenic mice themselves developed reduced numbers of peripheral CD4+CD25+ Treg and were more susceptible to the induction of colitis, which could be prevented by the transfer of wild-type Treg. These data indicate that TGF-β signaling in CD4+CD25+ Treg is required for their in vivo expansion and suppressive capacity.
Cutting Edge: TCR Revision Occurs in Germinal Centers
Authors: Cooper Cristine J. , Turk Gail L. , Sun Mingyi , Farr Andrew G. , Fink Pamela J.
Published: April 2014

Mouse CD4+Vβ5+ T cells recognize a peripherally expressed superantigen encoded by an endogenous retrovirus. Ag encounter tolerizes the mature CD4 T cell compartment, either by deletion of autoreactive cells or by TCR revision. This latter process is driven by TCRβ rearrangement through RAG activity and results in the rescue of cells expressing novel TCRs that no longer recognize the tolerogen. Consistent with the notion that revising T cells represent a distinct peripheral T cell population, we now show that these lymphocyte blasts express a hybrid effector/memory phenotype and are not undergoing cell division. A population of revising T cells is CD40+, expresses the germinal center (GC) marker CXCR5, and is Vβ5lowThy-1low. Histology reveals that, consistent with their surface Ag phenotype, T cells undergoing TCR revision are enriched in splenic GCs. These data demonstrate that TCR revision is a multistep tolerance pathway supported by the unique microenvironment provided by GCs.
Cutting Edge: A Critical Role for CD70 in CD8 T Cell Priming by CD40-Licensed APCs
Authors: Taraban Vadim Y. , Rowley Tania F. , Al-Shamkhani Aymen
Published: April 2014

The CD154/CD40 interaction is an important pathway of CD4 T cell help for CD8 T cell responses. In this study, we address the role of CD70, a member of the TNF superfamily and the ligand for the T cell costimulatory receptor CD27, in CD40-mediated priming of CD8 T cells. Using an agonistic anti-CD40 mAb to mimic the CD154/CD40 interaction we demonstrate that the priming of OT-I TCR transgenic or endogenous mouse OVA-specific CD8 T cells is critically dependent on CD70/CD27 interaction. CD70 blockade inhibited CD40-mediated clonal expansion of CD8 T cells and reduced the number of memory CD8 T cells generated. Furthermore, CD70 blockade during the initial priming of CD8 T cells inhibited the ability of memory CD8 T cells to expand in response to a second encounter with Ag. Our data indicate that CD70 expression on APCs plays a key role in CD40-dependent CD8 T cell responses.
Plasmacytoid Dendritic Cell Recruitment by Immobilized CXCR3 Ligands
Authors: Kohrgruber Norbert , Gröger Marion , Meraner Paul , Kriehuber Ernst , Petzelbauer Peter , Brandt Sabine , Stingl Georg , Rot Antal , Maurer Dieter
Published: April 2014

Plasmacytoid dendritic cells (pDCs) recognize microbes, viruses in particular, and provide unique means of innate defense against them. The mechanism of pDC tissue recruitment remained enigmatic because the ligands of CXCR3, the cardinal chemokine receptor on pDCs, have failed to induce in vitro chemotaxis of pDCs in the absence of additional chemokines. In this study, we demonstrate that CXCR3 is sufficient to induce pDC migration, however, by a migratory mechanism that amalgamates the features of haptotaxis and chemorepulsion. To mediate “haptorepulsion” of pDCs, CXCR3 requires the encounter of its cognate ligands immobilized, optimally by heparan sulfate, in a form of a negative gradient. This is the first report of the absolute requirement of chemokine immobilization and presentation for its in vitro promigratory activity. The paradigmatic example of pDC haptorepulsion described here may represent a new pathophysiologically relevant migratory mechanism potentially used by other cells in response to other chemokines.
IL-12 Gene Therapy Is an Effective Therapeutic Strategy for Hepatocellular Carcinoma in Immunosuppressed Mice
Authors: Harada Noboru , Shimada Mitsuo , Okano Shinji , Suehiro Taketoshi , Soejima Yuji , Tomita Yukihiro , Maehara Yoshihiko
Published: April 2014

Immunosuppressive therapy for organ transplantation is essential for controlling rejection. When liver transplantation is performed as a therapy for hepatocellular carcinoma (HCC), recurrent HCC is one of the most fatal complications. In this study, we show that intratumoral murine IL-12 (mIL-12) gene therapy has the potential to be an effective treatment for malignancies under immunosuppression. C3H mice (H-2k), injected with FK506 (3 mg/kg) i.p., were s.c. implanted with 2.5 × 106 MH134 cells (H-2k) and we treated the established HCC with electroporation-mediated gene therapy using mIL-12 plasmid DNA. Intratumoral gene transfer of mIL-12 elevated intratumoral mIL-12, IFN-γ, and IFN-γ-inducible protein-10, significantly reduced the number of microvessels and inhibited the growth of HCC, compared with HCC-transferred control pCAGGS plasmid. The inhibition of tumor growth in immunosuppressed mice was comparable with that of mIL-12 gene therapy in immunocompetent mice. Intratumoral mIL-12 gene therapy enhanced lymphocytic infiltration into the tumor and elicited the MH134-specific CTL response even under FK506. The dose of FK506 was sufficient to prevent the rejection of distant allogenic skin grafts (BALB/c mice, H-2d) and tumors, B7-p815 (H-2d) used as transplants, during mIL-12 gene therapy against MH134. Ab-mediated depletion studies suggested that the inhibition of tumor growth, neovascularization, and spontaneous lung metastasis by mIL-12 was dependent almost entirely on NK cells and partially on T cells. These results suggest that intratumoral mIL-12 gene therapy is a potent effective strategy not only to treat recurrences of HCC in liver transplantation, but also to treat solid malignant tumors in immunosuppressed patients with transplanted organ.
IFNβ Accelerates Autoimmune Type 1 Diabetes in Nonobese Diabetic Mice and Breaks the Tolerance to β Cells in Nondiabetes-Prone Mice
Authors: Alba Aurora , Puertas M. Carmen , Carrillo Jorge , Planas Raquel , Ampudia Rosa , Pastor Xavier , Bosch Fatima , Pujol-Borrell Ricardo , Verdaguer Joan , Vives-Pi Marta
Published: April 2014

Genetic and environmental factors are decisive in the etiology of type 1 diabetes. Viruses have been proposed as a triggering environmental event and some evidences have been reported: type I IFNs exist in the pancreata of diabetic patients and transgenic mice expressing these cytokines in β cells develop diabetes. To determine the role of IFNβ in diabetes, we studied transgenic mice expressing human IFNβ in the β cells. Autoimmune features were found: MHC class I islet hyperexpression, T and B cells infiltrating the islets and transfer of the disease by lymphocytes. Moreover, the expression of β2-microglobulin, preproinsulin, and glucagon in the thymus was not altered by IFNβ, thus suggesting that the disease is caused by a local effect of IFNβ, strong enough to break the peripheral tolerance to β cells. This is the first report of the generation of NOD (a model of spontaneous autoimmune diabetes) and nonobese-resistant (its homologous resistant) transgenic mice expressing a type I IFN in the islets: transgenic NOD and nonobese-resistant mice developed accelerated autoimmune diabetes with a high incidence of the disease. These results indicate that the antiviral cytokine IFNβ breaks peripheral tolerance to β cells, influences the insulitis progression and contributes to autoimmunity in diabetes and nondiabetes- prone mice.
Follicular Dendritic Cells Produce IL-15 That Enhances Germinal Center B Cell Proliferation in Membrane-Bound Form
Authors: Park Chan-Sik , Yoon Sun-Ok , Armitage Richard J. , Choi Yong Sung
Published: April 2014

Factors that control the survival and proliferation of Ag-stimulated B cells within the germinal center (GC) are crucial for humoral immune responses with high affinity Abs against infectious agents. The follicular dendritic cell (FDC) is known as a key cellular component of the GC microenvironment for GC-B cell survival and proliferation. In this study, we report that IL-15 is produced by human FDC in vivo and by an FDC cell line, FDC/HK cells, in vitro. IL-15 is captured by IL-15Rα on the surface of FDC/HK cells. The surface IL-15 is functionally active and augments GC-B cell proliferation. Because GC-B cells have the signal-transducing components (IL-2/15Rβγ), but not a receptor for binding of soluble IL-15 (IL-15Rα), IL-15 signaling is possibly transduced by transpresentation from FDCs to GC-B cells via cell-cell contact. Together, these results suggest that IL-15 from FDC, in membrane-bound form, plays an important role in supporting GC-B cell proliferation, proposing a new target for immune modulation as well as treatment of B cell tumors of GC origin.
IL-19 Induced Th2 Cytokines and Was Up-Regulated in Asthma Patients
Authors: Liao Sheng-Chin , Cheng Yung-Chih , Wang Yo-Ching , Wang Chiung-Wen , Yang San-Ming , Yu Chun-Keung , Shieh Chi-Chang , Cheng Kuo-Chen , Lee Meng-Feng , Chiang Shyh-Ren , Shieh Jiunn-Min , Chang Ming-Shi
Published: April 2014

IL-19 belongs to the IL-10 family, which includes IL-10, IL-19, IL-20, IL-22, melanoma differentiation-associated gene-7 (IL-24), and AK155 (IL-26). IL-10 has been shown to inhibit allergen-induced airway hyperreactivity and inflammation. To determine whether IL-19 was also associated with asthma, we used ELISA to analyze the serum level of IL-19 in patients with asthma and found that their serum IL-19 levels were twice those of healthy controls. Patients with a high level of IL-19 also had high levels of IL-4 and IL-13. In a dust mite-induced murine model of asthma, we found that IL-19 level in asthmatic BALB/cJ mice was also twice that of healthy control mice. IL-19 transcript was also induced in the lungs of asthmatic mice. Electroporation i.m. of the IL-19 gene into healthy mice up-regulated IL-4 and IL-5, but not IL-13. However, IL-19 up-regulated IL-13 in asthmatic mice. In vitro, IL-19 induced IL-4, IL-5, IL-10, and IL-13 production by activated T cells. Activation of T cells was required for induction of IL-13 because IL-19 did not induce IL-13 production on nonstimulated T cells. Taken together, these results demonstrated that IL-19 up-regulates Th2 cytokines on activated T cells and might play an important role in the pathogenesis of asthma.
Biochemical Analysis of the Regulatory T Cell Protein Lymphocyte Activation Gene-3 (LAG-3; CD223)
Authors: Li Nianyu , Workman Creg J. , Martin Stefani M. , Vignali Dario A. A.
Published: April 2014

Lymphocyte activation gene-3 (LAG-3; CD223) is a CD4-related transmembrane protein that binds to MHC class II molecules. We have recently shown that LAG-3 is required for maximal regulatory T cell function, and that ectopic expression of LAG-3 is sufficient to confer regulatory activity. In this study we show that LAG-3 is cleaved within the D4 transmembrane domain connecting peptide into two fragments that remain membrane associated: a 54-kDa fragment that contains all the extracellular domains and oligomerizes with full-length LAG-3 (70 kDa) on the cell surface via the D1 domain, and a 16-kDa peptide that contains the transmembrane and cytoplasmic domains. This NH2-terminal fragment is subsequently released as soluble LAG-3 (sLAG-3), a process that is increased after T cell activation in vitro and in vivo, and is found in the sera of C57BL/6 and RAG-1−/− mice. Modulation of LAG-3 cleavage may contribute to the function of this key regulatory T cell protein.
A Novel Adjuvant for Mucosal Immunity to HIV-1 gp120 in Nonhuman Primates
Authors: Yoshino Naoto , Lü Fabien X.-S. , Fujihashi Kohtaro , Hagiwara Yukari , Kataoka Kosuke , Lu Ding , Hirst Linda , Honda Mitsuo , van Ginkel Frederik W. , Takeda Yoshifumi , Miller Christopher J. , Kiyono Hiroshi , McGhee Jerry R.
Published: April 2014

The development of a safe and effective mucosal adjuvant is a crucial step toward a mucosal HIV/AIDS vaccine. This study seeks to determine the promise of a nontoxic mutant of cholera toxin (mCT; E112K) as a mucosal adjuvant in nonhuman primates. HIV-1 gp120 was nasally administered together with mCT E112K or native CT (nCT) as adjuvant on five to six occasions over a 6- to 8-wk period to groups of four rhesus macaques and alone to two monkeys that acted as controls. Macaques given nasal gp120 with either mCT E112K or nCT showed elevated gp120-specific IgG and IgA Ab responses with virus-neutralizing activity in both their plasma and mucosal external secretions, as well as higher numbers of gp120-specific IgA Ab-forming cells in their mucosal and peripheral lymphoid tissues and of IL-4-producing Th2-type CD4-positive (CD4+) T cells than did controls. Even though significant mucosal adjuvanticity was seen with both mCT E112K and nCT, neuronal damage was observed only in the nCT-treated, but not in the control or mCT E112K-treated groups. These results clearly show that mCT E112K is an effective and safe mucosal adjuvant for the development of a nasal HIV/AIDS vaccine.
Gene Expression Profiling of Host Response in Models of Acute HIV Infection
Authors: Bosinger Steven E. , Hosiawa Karoline A. , Cameron Mark J. , Persad Desmond , Ran Longsi , Xu Luoling , Boulassel Mohamed R. , Parenteau Monique , Fournier Jocelyn , Rud Erling W. , Kelvin David J.
Published: April 2014

HIV infection is characterized by a host response composed of adaptive and innate immunity that partially limits viral replication; however, it ultimately fails in eradicating the virus. To model host gene expression during acute HIV infection, we infected cynomolgus macaques with the SIV/HIV-1 chimeric virus, SHIV89.6P, and profiled gene expression in peripheral blood over a 5-wk period using a high density cDNA microarray. We demonstrate that viral challenge induced a widespread suppression of genes regulating innate immunity, including the LPS receptors, CD14 and TLR4. An overexpression of 16 IFN-stimulated genes was also observed in response to infection; however, it did not correlate with control over viral titers. A statistical analysis of the dataset identified 10 genes regulating apoptosis with differential expression during the first 2 wk of infection (p < 0.004). Quantitative real-time PCR verified transcriptional increases in IFN-α-inducible genes and decreases in genes regulating innate immunity. Therefore, the persistence of high viral loads despite an extensive IFN response suggests that HIV can resist in vivo IFN treatment despite published reports of in vitro efficacy. The transcriptional suppression of genes regulating innate immunity may allow HIV to evade acute host responses and establish a chronic infection and may reduce innate host defense against opportunistic infections.