bluuebunny/crossref_metadata_2025 huggingface dataset:
Enteric Nematodes Induce Stereotypic STAT6-Dependent Alterations in Intestinal Epithelial Cell Function
Authors: Madden Kathleen B. , Yeung Karla Au , Zhao Aiping , Gause William C. , Finkelman Fred D. , Katona Ildy M. , Urban Joseph F. , Shea-Donohue Terez
Published: April 2014

Infection with gastrointestinal nematodes exerts profound effects on both the immune and physiological responses of the host. We showed previously that the Th2 cytokines, IL-4 and IL-13, induce STAT6-dependent changes in intestinal epithelial cell permeability, absorption, and secretion that are similar to those observed in a secondary infection with Heligmosomoides polygyrus. In the current study we investigated whether nematode-induced effects on epithelial cell function were 1) generic, 2) dependent upon STAT6, and 3) attributable to direct effects on the epithelial cells themselves or mediated by effects on enteric nerves. Our results demonstrate that infection of BALB/c mice with three different gastrointestinal nematodes (H. polygyrus, Nippostrongylus brasiliensis, and Trichinella spiralis) alters intestinal epithelial cell function by decreasing resistance, glucose absorption, and secretory responses to 5-hydroxytryptamine and acetylcholine, two critical mediators in the submucosal reflex pathway. These modified responses are dependent on STAT6 and are the result of both direct effects and indirect effects mediated through enteric nerves.
Suppressor of Cytokine Signaling-1 Overexpression Protects Pancreatic β Cells from CD8+ T Cell-Mediated Autoimmune Destruction
Authors: Chong Mark M. W. , Chen Ye , Darwiche Rima , Dudek Nadine L. , Irawaty Windy , Santamaria Pere , Allison Janette , Kay Thomas W. H. , Thomas Helen E.
Published: April 2014

In type 1 diabetes, cytokine action on β cells potentially contributes to β cell destruction by direct cytotoxicity, inducing Fas expression, and up-regulating class I MHC and chemokine expression to increase immune recognition. To simultaneously block β cell responsiveness to multiple cytokines, we overexpressed suppressor of cytokine signaling-1 (SOCS-1). This completely prevented progression to diabetes in CD8+ TCR transgenic nonobese diabetic (NOD) 8.3 mice without affecting pancreas infiltration and partially prevented diabetes in nontransgenic NOD mice. SOCS-1 appeared to protect at least in part by inhibiting TNF- and IFN-γ-induced Fas expression on β cells. Fas expression was up-regulated on β cells in vivo in prediabetic NOD8.3 mice, and this was inhibited by SOCS-1. Additionally, IFN-γ-induced class I MHC up-regulation and TNF- and IFN-γ-induced IL-15 expression by β cells were inhibited by SOCS-1, which correlated with suppressed 8.3 T cell proliferation in vitro. Despite this, 8.3 T cell priming in vivo appeared unaffected. Therefore, blocking β cell responses to cytokines impairs recognition by CD8+ T cells and blocks multiple mechanisms of β cell destruction, but does not prevent T cell priming and recruitment to the islets. Our findings suggest that increasing SOCS-1 expression may be useful as a strategy to block CD8+ T cell-mediated type 1 diabetes as well as to more generally prevent cytokine-dependent tissue destruction in inflammatory diseases.
Activation of Endoplasmic Reticulum-Specific Stress Responses Associated with the Conformational Disease Z α1-Antitrypsin Deficiency
Authors: Lawless Matthew W. , Greene Catherine M. , Mulgrew Alan , Taggart Clifford C. , O’Neill Shane J. , McElvaney Noel G.
Published: April 2014

Conformational diseases are a class of disorders associated with aberrant protein accumulation in tissues and cellular compartments. Z α1-antitrypsin (A1AT) deficiency is a genetic disease associated with accumulation of misfolded A1AT in the endoplasmic reticulum (ER) of hepatocytes. We sought to identify intracellular events involved in the molecular pathogenesis of Z A1AT-induced liver disease using an in vitro model system of Z A1AT ER accumulation. We investigated ER stress signals induced by Z A1AT and demonstrated that both the ER overload response and the unfolded protein response were activated by mutant Z A1AT, but not wild-type M A1AT. Interestingly, activation of the unfolded protein response pathway required an additional insult, whereas NF-κB activation, a hallmark of the ER overload response, was constitutive. These findings have important implications for the design of future therapeutics for Z A1AT liver disease and may also impact on drug design for other conformational diseases.
Circulating Immune Complexes Augment Severity of Antibody-Mediated Myasthenia Gravis in Hypogammaglobulinemic RIIIS/J Mice
Authors: Tüzün Erdem , Scott Benjamin G. , Yang Huan , Wu Bo , Goluszko Elzbieta , Guigneaux Michelle , Higgs Stephen , Christadoss Premkumar
Published: April 2014

Experimental autoimmune myasthenia gravis (EAMG) is severe in RIIIS/J mice, despite a significant B cell immunodeficiency and a massive TCR Vβ gene deletion. Severity of EAMG in RIIIS/J mice is greater than MHC-identical (H-2r) B10.RIII mice, suggesting the influence of non-MHC genes as an EAMG-potentiating factor in this strain. To delineate the role of deleted TCR Vβ genes in RIIIS/J mice, we obtained (RIIIS/J × B10.RIII)F1 (Vβb/c) × RIIIS/J (Vβc) backcross mice using Mendelian genetic methods and immunized them with acetylcholine receptor. EAMG susceptibility was not elevated in mice with Vβc genotype having 70% Vβ gene deletion. Next, we performed microarray analysis on 12,488 spleen cDNAs obtained from spleens of naive RIIIS/J and B10.RIII mice. In RIIIS/J mice, 263 cDNAs were overexpressed and 303 cDNAs were underexpressed greater than 2-fold, compared with B10.RIII mice. TCR gene expression was augmented, whereas NK receptor, C1q, and C3 gene expressions were diminished in RIIIS/J mice. RIIIS/J mice also had increased lymph node T cell counts, elevated serum anti-AChR Ab levels, and serum C3 and C1q-conjugated circulating immune complex levels. A direct correlation between increased serum C1q-conjugated circulating immune complex levels and disease severity was observed in RIIIS/J mice.
Treatment with α-Galactosylceramide Attenuates the Development of Bleomycin-Induced Pulmonary Fibrosis
Authors: Kimura Toru , Ishii Yukio , Morishima Yuko , Shibuya Akira , Shibuya Kazuko , Taniguchi Masaru , Mochizuki Mie , Hegab Ahmed E. , Sakamoto Tohru , Nomura Akihiro , Sekizawa Kiyohisa
Published: April 2014

Pulmonary fibrosis is an end-stage disorder for which efficacious therapeutic options are not readily available. Although its pathogenesis is poorly understood, pulmonary fibrosis occurs as a result of various inflammations. NKT cells modulate inflammation because of their ability to produce large amounts of cytokines by stimulation with their glycolipid ligand. In the present study, we investigated the effects of α-galactosylceramide (α-GalCer), a selective NKT cell ligand, on the development of bleomycin-induced pulmonary fibrosis. Treatment of mice with α-GalCer prolonged their survival under bleomycin administration by attenuating the development of pulmonary fibrosis. The protective effects of α-GalCer were associated with an increase in the pulmonary level of IFN-γ and a decrease in the pulmonary level of fibrogenic cytokines such as TGF-β and connective tissue growth factor. The initial pulmonary inflammation caused by bleomycin was also attenuated by α-GalCer with the reduction of the macrophage inflammatory protein-2 level. The protective effects of α-GalCer were markedly reduced in mice lacking NKT cells or as a result of treatment with anti-IFN-γ Ab. These results suggest that α-GalCer suppresses bleomycin-induced acute pulmonary inflammation and thus attenuates the development of pulmonary fibrosis possibly by regulating several cytokine levels.
Peroxisome Proliferator-Activated Receptor α Agonists as Therapy for Autoimmune Disease
Authors: Lovett-Racke Amy E. , Hussain Rehana Z. , Northrop Sara , Choy Judy , Rocchini Anne , Matthes Lela , Chavis Janet A. , Diab Asim , Drew Paul D. , Racke Michael K.
Published: April 2014

Peroxisome proliferator-activated receptors (PPARs) are members of the nuclear hormone receptor superfamily. PPARγ ligands, which include the naturally occurring PG metabolite 15-deoxy-Δ12,14-PGJ2 (15d-PGJ2), as well as thiazolidinediones, have been shown to have anti-inflammatory activity. The PPARα agonists, gemfibrozil, ciprofibrate, and fenofibrate, have an excellent track history as oral agents used to treat hypertriglyceridemia. In the present study, we demonstrate that these PPARα agonists can increase the production of the Th2 cytokine, IL-4, and suppress proliferation by TCR transgenic T cells specific for the myelin basic protein Ac1–11, as well as reduce NO production by microglia. Oral administration of gemfibrozil and fenofibrate inhibited clinical signs of experimental autoimmune encephalomyelitis. More importantly, gemfibrozil was shown to shift the cytokine secretion of human T cell lines by inhibiting IFN-γ and promoting IL-4 secretion. These results suggest that PPARα agonists such as gemfibrozil and fenofibrate, may be attractive candidates for use in human inflammatory conditions such as multiple sclerosis.
Dysregulated FcεRI Signaling and Altered Fyn and SHIP Activities in Lyn-Deficient Mast Cells
Authors: Hernandez-Hansen Valerie , Smith Alexander J. , Surviladze Zurab , Chigaev Alexandre , Mazel Tomas , Kalesnikoff Janet , Lowell Clifford A. , Krystal Gerald , Sklar Larry A. , Wilson Bridget S. , Oliver Janet M.
Published: April 2014

Studies in B cells from Lyn-deficient mice have identified Lyn as both a kinetic accelerator and negative regulator of signaling through the BCR. The signaling properties of bone marrow-derived mast cells from Lyn−/− mice (Lyn−/− BMMCs) have also been explored, but their signaling phenotype remains controversial. We confirm that Lyn−/− BMMCs release more β-hexosaminidase than wild-type BMMCs following FcεRI cross-linking and show that multiple mast cell responses to FcεRI cross-linking (the phosphorylation of receptor subunits and other proteins, the activation of phospholipase Cγ isoforms, the mobilization of Ca2+, the synthesis of phosphatidylinositol 3,4,5-trisphosphate, the activation of the α4β1 integrin, VLA-4) are slow to initiate in Lyn−/− BMMCs, but persist far longer than in wild-type cells. Mechanistic studies revealed increased basal as well as stimulated phosphorylation of the Src kinase, Fyn, in Lyn−/− BMMCs. Conversely, there was very little basal or stimulated tyrosine phosphorylation or activity of the inositol phosphatase, SHIP, in Lyn−/− BMMCs. We speculate that Fyn may substitute (inefficiently) for Lyn in signal initiation in Lyn−/− BMMCs. The loss of SHIP phosphorylation and activity very likely contributes to the increased levels of phosphatidylinositol 3,4,5-trisphosphate and the excess FcεRI signaling in Lyn−/− BMMCs. The unexpected absence of the transient receptor potential channel, Trpc4, from Lyn−/− BMMCs may additionally contribute to their altered signaling properties.
Cooperative Prosurvival Activity by ERK and Akt in Human Alveolar Macrophages is Dependent on High Levels of Acid Ceramidase Activity
Authors: Monick Martha M. , Mallampalli Rama K. , Bradford Mary , McCoy Diann , Gross Thomas J. , Flaherty Dawn M. , Powers Linda S. , Cameron Kelli , Kelly Samuel , Merrill Alfred H. , Hunninghake Gary W.
Published: April 2014

Human alveolar macrophages are unique in that they have an extended life span in contrast to precursor monocytes. In evaluating the role of sphingolipids in alveolar macrophage survival, we found high levels of sphingosine, but not sphingosine-1-phosphate. Sphingosine is generated by the action of ceramidase(s) on ceramide, and alveolar macrophages have high constitutive levels of acid ceramidase mRNA, protein, and activity. The high levels of acid ceramidase were specific to alveolar macrophages, because there was little ceramidase protein or activity (or sphingosine) in monocytes from matching donors. In evaluating prolonged survival of alveolar macrophages, we observed a requirement for constitutive activity of ERK MAPK and the PI3K downstream effector Akt. Blocking acid ceramidase but not sphingosine kinase activity in alveolar macrophages led to decreased ERK and Akt activity and induction of cell death. These studies suggest an important role for sphingolipids in prolonging survival of human alveolar macrophages via distinct survival pathways.
Inducing Experimental Arthritis and Breaking Self-Tolerance to Joint-Specific Antigens with Trackable, Ovalbumin-Specific T Cells
Authors: Maffia Pasquale , Brewer James M. , Gracie J. Alastair , Ianaro Angela , Leung Bernard P. , Mitchell Paul J. , Smith Karen M. , McInnes Iain B. , Garside Paul
Published: April 2014

The importance of T cell Ag specificity and Th1 vs Th2 phenotype in synovial inflammation remains controversial. Using OVA-specific TCR transgenic T cells from DO11.10 mice, we demonstrate that mice receiving Th1, but not Th2, cells display a transient arthritis following immunization that is characterized by synovial hyperplasia, cellular infiltration, and cartilage erosion. OVA-specific T cells also accumulated in inflamed joints, suggesting that they could exert their inflammatory effect locally in the joint or in the draining lymph node. Importantly, this pathology was accompanied by a breakdown in self-tolerance, as evidenced by the induction of collagen-specific T and B cell responses. This model directly demonstrates a pivotal role for Th1 cells of an irrelevant specificity in the development of inflammatory arthritis. Furthermore, the ability to track these cells in vivo will make feasible studies revealing the dynamic role of T cells in arthritis.
Cutting Edge: Physiologic Attenuation of Proinflammatory Transcription by the Gs Protein-Coupled A2A Adenosine Receptor In Vivo
Authors: Lukashev Dmitriy , Ohta Akio , Apasov Sergey , Chen Jiang-Fan , Sitkovsky Michail
Published: April 2014

The A2A adenosine receptor plays a critical role in the physiologic immunosuppressive pathway that protects normal tissues from excessive collateral damage by overactive immune cells and their proinflammatory cytokines. In this study, we examine and clarify the mechanism of tissue protection by extracellular adenosine using A2AR-deficient mice and show that the A2AR inhibits TLR-induced transcription of proinflammatory cytokines in vivo. The observed increase in proinflammatory cytokines mRNA in A2AR-deficient mice was associated with enhanced activity of the NF-κB transcription factor. These observations provide the genetic in vivo evidence for attenuation of proinflammatory transcriptional activity of NF-κB by a “metabokine” adenosine and point to the need to re-evaluate the regulation of other transcription factors in hypoxic and adenosine-rich microenvironments of inflamed normal tissues and solid tumors.
Alteration of Cell Surface Sialylation Regulates Antigen-Induced Naive CD8+ T Cell Responses
Authors: Pappu Bhanu P. , Shrikant Protul A.
Published: April 2014

The strength of interactions with APC instructs naive T cells to undergo programmed expansion and differentiation, which is largely determined by the peptide affinity and dose as well as the duration of TCR ligation. Although, most ligands mediating these interactions are terminally sialylated, the impact of the T cell sialylation status on Ag-dependent response remains poorly understood. In this study, by monitoring TCR transgenic CD8+ T cells, OT-I, we show that biochemical desialylation of naive OT-I T cells increases their sensitivity for agonist as well as partial agonist peptides. Desialylation enhances early activation and shortens the duration of TCR stimulation required for proliferation and differentiation, without increasing apoptosis. Moreover, desialylation of naive OT-I T cells augments their response to tumor-presented Ag. These results provide direct evidence for a regulatory role for sialylation in Ag-dependent CD8+ T cell responses and offer a new approach to sensitize or dampen Ag-specific CD8+ T cell responses.
Sustained Early Growth Response Gene 3 Expression Inhibits the Survival of CD4/CD8 Double-Positive Thymocytes
Authors: Xi Hongkang , Kersh Gilbert J.
Published: April 2014

In the absence of selection, CD4+, CD8+ double-positive (DP) thymocytes will die after 3–4 days. The mechanism for regulating the life span of DP cells is unknown. Previously, we demonstrated that the zinc finger transcription factor, early growth response gene 3 (Egr3), promotes proliferation during the transition from double negative (DN) to DP. In this study we demonstrate a novel role for Egr3 in controlling DP thymocyte survival in mice. Constitutive transgenic expression of Egr3 in thymocytes increases apoptosis among DP cells and shortens their survival in vitro. In addition, DP cells in Egr3 transgenic mice have poor expression of TCRα, and based on the predominant usage of 3′ Vα and 5′ Jα gene segments, the low level of TCRα expression is a result of DP death soon after the initiation of TCRα rearrangements. Constitutive transgenic expression of Egr3 results in poor expression of Bcl-xL and the thymic isoform of retinoic acid receptor-related orphan receptor γ (RORγt) in DP thymocytes, two molecules that are required in DP cells for normal life span. Egr3 expression induced by pre-TCR signals in nontransgenic mice is transient and returns to background levels before RORγt or Bcl-xL is induced. The data support a model in which Egr3 must be transiently induced in response to pre-TCR signals, so that the expression of the prosurvival molecules, RORγt and Bcl-xL, can be elevated only after the proliferative signal provided by Egr3 has subsided.
Lipopolysaccharide-Induced Macrophage Inflammatory Response Is Regulated by SHIP
Authors: Fang Huiqing , Pengal Ruma A. , Cao Xianhua , Ganesan Latha P. , Wewers Mark D. , Marsh Clay B. , Tridandapani Susheela
Published: April 2014

LPS stimulates monocytes/macrophages through TLR4, resulting in the activation of a series of signaling events that potentiate the production of inflammatory mediators. Recent reports indicated that the inflammatory response to LPS is diminished by PI3K, through the activation of the serine/threonine kinase Akt. SHIP is an inositol phosphatase that can reverse the activation events initiated by PI3K, including the activation of Akt. However, it is not known whether SHIP is involved in TLR4 signaling. In this study, we demonstrate that LPS stimulation of Raw 264.7 mouse macrophage cells induces the association of SHIP with lipid rafts, along with IL-1R-associated kinase. In addition, SHIP is tyrosine phosphorylated upon LPS stimulation. Transient transfection experiments analyzing the function of SHIP indicated that overexpression of a wild-type SHIP, but not the SHIP Src homology 2 domain-lacking catalytic activity, up-regulates NF-κB-dependent gene transcription in response to LPS stimulation. These results suggest that SHIP positively regulates LPS-induced activation of Raw 264.7 cells. To test the validity of these observations in primary macrophages, LPS-induced events were compared in bone marrow macrophages derived from SHIP+/+ and SHIP−/− mice. Results indicated that LPS-induced MAPK phosphorylation is enhanced in SHIP+/+ cells, whereas Akt phosphorylation is enhanced in SHIP−/− cells compared with SHIP+/+ cells. Finally, LPS-induced TNF-α and IL-6 production was significantly lower in SHIP−/− bone marrow-derived macrophages. These results are the first to demonstrate a role for SHIP in TLR4 signaling, and propose that SHIP is a positive regulator of LPS-induced inflammation.
The Structure of H-2Kb and Kbm8 Complexed to a Herpes Simplex Virus Determinant: Evidence for a Conformational Switch That Governs T Cell Repertoire Selection and Viral Resistance
Authors: Webb Andrew I. , Borg Natalie A. , Dunstone Michelle A. , Kjer-Nielsen Lars , Beddoe Travis , McCluskey James , Carbone Francis R. , Bottomley Stephen P. , Aguilar Marie-Isabel , Purcell Anthony W. , Rossjohn Jamie
Published: April 2014

Polymorphism within the MHC not only affects peptide specificity but also has a critical influence on the T cell repertoire; for example, the CD8 T cell response toward an immunodominant HSV glycoprotein B peptide is more diverse and of higher avidity in H-2bm8 compared with H-2b mice. We have examined the basis for the selection of these distinct antiviral T cell repertoires by comparing the high-resolution structures of Kb and Kbm8, in complex with cognate peptide Ag. Although Kb and Kbm8 differ by four residues within the Ag-binding cleft, the most striking difference in the two structures was the disparate conformation adopted by the shared residue, Arg62. The altered dynamics of Arg62, coupled with a small rigid-body movement in the α1 helix encompassing this residue, correlated with biased Vα usage in the B6 mice. Moreover, an analysis of all known TCR/MHC complexes reveals that Arg62 invariably interacts with the TCR CDR1α loop. Accordingly, Arg62 appears to function as a conformational switch that may govern T cell selection and protective immunity.
Proinflammatory Chemokines, Such as C-C Chemokine Ligand 3, Desensitize μ-Opioid Receptors on Dorsal Root Ganglia Neurons
Authors: Zhang Ning , Rogers Thomas J. , Caterina Michael , Oppenheim Joost J.
Published: April 2014

Pain is one of the hallmarks of inflammation. Opioid receptors mediate antipain responses in both the peripheral nervous system and CNS. In the present study, pretreatment of CCR1:μ-opioid receptor/HEK293 cells with CCL3 (MIP-1α) induced internalization of μ-opioid receptors and severely impaired the μ-opioid receptor-mediated inhibition of cAMP accumulation. Immunohistochemical staining showed that CCR1 and μ-opioid receptors were coexpressed on small to medium diameter neurons in rat dorsal root ganglion. Analysis of ligand-induced calcium flux showed that both types of receptors were functional. Pretreatment of neurons with CCL3 exhibited an impaired [d-Ala2,N-MePhe4,Gly-o15]enkephalin-elicited calcium response, indicative of the heterologous desensitization of μ-opioid receptors. Other chemokines, such as CCL2, CCL5, and CXCL8, exhibited similar inhibitory effects. Our data indicate that proinflammatory chemokines are capable of desensitizing μ-opioid receptors on peripheral sensory neurons, providing a novel potential mechanism for peripheral inflammation-induced hyperalgesia.
Evidence That Invasion-Inhibitory Antibodies Specific for the 19-kDa Fragment of Merozoite Surface Protein-1 (MSP-119) Can Play a Protective Role against Blood-Stage Plasmodium falciparum Infection in Individuals in a Malaria Endemic Area of Africa
Authors: John Chandy C. , O’Donnell Rebecca A. , Sumba Peter O. , Moormann Ann M. , de Koning-Ward Tania F. , King Christopher L. , Kazura James W. , Crabb Brendan S.
Published: April 2014

The C-terminal 19-kDa fragment of Plasmodium falciparum merozoite surface protein-1 (MSP-119) is a target of protective Abs against blood-stage infection and a leading candidate for inclusion in a human malaria vaccine. However, the precise role, relative importance, and mechanism of action of Abs that target this protein remain unclear. To examine the potential protective role of Abs to MSP-119 in individuals naturally exposed to malaria, we conducted a treatment time to infection study over a 10-wk period in 76 residents of a highland area of western Kenya during a malaria epidemic. These semi-immune individuals were not all equally susceptible to reinfection with P. falciparum following drug cure. Using a new neutralization assay based on transgenic P. falciparum expressing the P. chabaudi MSP-119 orthologue, individuals with high-level MSP-119-specific invasion-inhibitory Abs (>75th percentile) had a 66% reduction in the risk of blood-stage infection relative to others in the population (95% confidence interval, 3–88%). In contrast, high levels of MSP-119 IgG or IgG subclass Abs measured by enzyme immunoassay with six different recombinant MSP-119 Ags did not correlate with protection from infection. IgG Abs measured by serology and functional invasion-inhibitory activity did not correlate with each other. These findings implicate an important protective role for MSP-119-specific invasion inhibitory Abs in immunity to blood-stage P. falciparum infection, and suggest that the measurement of MSP-119 specific inhibitory Abs may serve as an accurate correlate of protection in clinical trials of MSP-1-based vaccines.
Rac2-Deficient Murine Macrophages Have Selective Defects in Superoxide Production and Phagocytosis of Opsonized Particles
Authors: Yamauchi Akira , Kim Chaekyun , Li Shijun , Marchal Christophe C. , Towe Jason , Atkinson Simon J. , Dinauer Mary C.
Published: April 2014

The Rho family GTPase Rac is a crucial participant in numerous cellular functions and acts as a molecular switch for signal transduction. Mice deficient in hemopoietic-specific Rac2 exhibited agonist-specific defects in neutrophil functions including chemoattractant-stimulated filamentous actin polymerization and chemotaxis, and superoxide production elicited by phorbol ester, fMLP, or IgG-coated particles, despite expression of the highly homologous Rac1 isoform. In this study, functional responses of Rac2-null murine macrophages were characterized to examine whether Rac2 also has nonredundant functions in this phagocytic lineage. In contrast to murine neutrophils, in which Rac1 and Rac2 are present in similar amounts, Rac1 was ∼4-fold more abundant than Rac2 in both bone marrow-derived and peritoneal exudate macrophages, and macrophage Rac1 levels were unchanged by the absence of Rac2. Accumulation of exudate macrophages during peritoneal inflammation was reduced in rac2−/− mice. FcγR-mediated phagocytosis of IgG-coated SRBC was also significantly decreased in Rac2-null macrophages, as was NADPH oxidase activity in response to phorbol ester or FcγR stimulation. However, phagocytosis and oxidant production stimulated by serum-opsonized zymosan was normal in rac2−/− macrophages. Macrophage morphology was also similar in wild-type and Rac2-null cells, as was actin polymerization induced by FcγR-mediated phagocytosis or M-CSF. Hence, Rac2-null macrophages have selective defects paralleling many of the observed functional defects in Rac2-null neutrophils. These results provide genetic evidence that although Rac2 is a relatively minor isoform in murine macrophages, it plays a nonoverlapping role with Rac1 to regulate host defense functions in this phagocyte lineage.
Regulated Recruitment of MHC Class II and Costimulatory Molecules to Lipid Rafts in Dendritic Cells
Authors: Meyer zum Bueschenfelde Christian O. , Unternaehrer Julia , Mellman Ira , Bottomly Kim
Published: April 2014

T cell activation has long been associated with the partitioning of Ag receptors and associated molecules to lipid microdomains. We now show that dendritic cells (DCs) also accomplish the selective recruitment to lipid rafts of molecules critical for Ag presentation. Using mouse bone marrow-derived DCs, we demonstrate that MHC class II molecules become substantially localized to rafts upon DC maturation. Even more striking is the fact that CD86 is recruited to rafts upon T cell-DC interaction. Recruitment is Ag dependent and requires CD28 on T cells. Despite the regulated recruitment of MHC class II and CD86 to rafts, unlike the counter-receptors in T cells, DCs do not polarize these molecules to sites of DC-T cell contact. This difference may reflect the necessity for DCs to interact with multiple T cells simultaneously and emphasizes that the biochemical and morphological correlates of lipid rafts are not necessarily equivalent.
The Class A Macrophage Scavenger Receptor Attenuates CXC Chemokine Production and the Early Infiltration of Neutrophils in Sterile Peritonitis
Authors: Cotena Alessia , Gordon Siamon , Platt Nick
Published: April 2014

The macrophage scavenger receptor (SR-A) is a multifunctional receptor that is associated with several important pathological conditions, including atherosclerosis. In this study, we show, using a sterile peritonitis model, that it can regulate the inflammatory response. SR-A null mice display an increased initial granulocytic infiltration because of overproduction of the CXC chemokines, MIP-2 and keratinocyte-derived cytokine. This differential response is dependent upon particle internalization and can be mimicked by advanced glycation end product-BSA-conjugated latex beads. Thus SR-A is a nonactivating receptor, which is the first example of a pattern recognition receptor that serves to counter the activities of proinflammatory receptors and attenuates the production of specific chemokines to ensure an inflammatory response of the appropriate magnitude.
Group IB Secretory Phospholipase A2 Stimulates CXC Chemokine Ligand 8 Production via ERK and NF-κB in Human Neutrophils
Authors: Jo Eun Jin , Lee Ha-Young , Lee Youl-Nam , Kim Jung Im , Kang Hyun-Kyu , Park Dae-Won , Baek Suk-Hwan , Kwak Jong-Young , Bae Yoe-Sik
Published: April 2014

Although the level of group IB secretory phospholipase A2 (sPLA2-IB) has been reported to be up-regulated during inflammatory response, the role of sPLA2-IB on the regulation of inflammation and immune responses has not been fully elucidated. In this study, we found that sPLA2-IB stimulates the expression and secretion of CXCL8 without affecting other proinflammatory cytokines, such as IL-1β or TNF α in human neutrophils. The induction of CXCL8 secretion by sPLA2-IB occurs at both the transcription and translational levels and correlates with activation of NF-κB. Moreover, the NF-κB inhibitors pyrrolidinedithiocarbamate, dexamethasone, or sulfasalazine were found to prevent CXCL8 production by sPLA2-IB in human neutrophils. In addition, the signaling events induced by sPLA2-IB included activation of the MAPK ERK and an increase in intracellular Ca2+, which are both required for CXCL8 production. The exogenous addition of sPLA2-IB did not induce arachidonic acid release from human neutrophils, and the inactivation of sPLA2-IB by EGTA did not affect CXCL8 production by sPLA2-IB in human neutrophils. Taken together, we suggest that sPLA2-IB plays a role in the modulation of inflammatory and immune responses via the sPLA2 receptor, by inducing CXCL8 in human neutrophils.
Differential Regulation of Th2 and Th1 Lung Inflammatory Responses by Protein Kinase Cθ
Authors: Salek-Ardakani Shahram , So Takanori , Halteman Beth S. , Altman Amnon , Croft Michael
Published: April 2014

In vitro and recent in vivo studies have identified protein kinase Cθ (PKCθ) as an important intermediate in signaling pathways leading to T cell activation, proliferation, and cytokine production. However, the importance of PKCθ to many T cell-driven inflammatory responses has not been demonstrated. In this study we show that although PKCθ is required for the development of a robust lung inflammatory response controlled by Th2 cells, it plays a lesser role in the development of a similar lung inflammatory response controlled by Th1 cells. PKCθ-deficient mice were strongly compromised in generating Th2 cells and exhibited reduced airway eosinophilia and Th2 cytokine production in lungs. PKCθ was required for the initial development of Th1 cells, with these cells exhibiting delayed kinetics of differentiation and accumulation. However, with recall Ag challenge via the airways, this defect was overcome, and lung infiltration and Th1 cytokine production were largely unimpaired in PKCθ-deficient animals. These data suggest that PKCθ can play roles in aspects of both Th2 and Th1 responses, but lung inflammation induced by Th2 cells is more dependent on this protein kinase than lung inflammation induced by Th1 cells.
Suppression of Ongoing Experimental Autoimmune Encephalomyelitis by Neutralizing the Function of the p28 Subunit of IL-27
Authors: Goldberg Ruth , Zohar Yaniv , Wildbaum Gizi , Geron Yifat , Maor Gila , Karin Nathan
Published: April 2014

IL-27 is a recently defined family member of the long-chain, four-helix bundle cytokines, which consist of EBI3, an IL-12p40-related protein, and p28, an IL-12p35-related polypeptide. The role of IL-27 in the regulation of experimental autoimmune encephalomyelitis has never been studied. We show in this study that neutralizing the in vivo function of IL-27 by Abs against IL-27 p28 rapidly suppressed an ongoing long-lasting disease in C57BL/6 mice. These Abs were then used to determine the mechanistic basis of disease suppression. We show in this study that IL-27 is involved not only in the polarization of naive T cells undergoing Ag-specific T cell activation, but also in promoting the proliferation and IFN-γ production by polarized T cells, including the long term Th1 line that has been previously selected against the target encephalitogenic determinant. This may explain in part why neutralizing IL-27 suppresses an already established disease in a very rapid and significant manner.
Cutting Edge: IL-5 Primes Th2 Cytokine-Producing Capacity in Eosinophils through a STAT5-Dependent Mechanism
Authors: Zhu Yuechun , Chen Luqiu , Huang Zan , Alkan Serhan , Bunting Kevin D. , Wen Renren , Wang Demin , Huang Hua
Published: April 2014

Both type-2 CD4+ Th cells (CD4+Th2) and type-2 innate effector cells play critical roles in generating type-2 immunity that can either be protective against parasitic infection or cause tissue damage in allergy and asthma. How innate effector cells acquire the capacity to produce Th2 cytokines is not entirely known. We previously showed that IL-4 induced differentiation of Th2 cytokine-producing eosinophils. To determine whether other Th2 cytokines can also induce Th2 cytokine-producing capacity in innate effector cells, we cultured bone marrow progenitor cells in the presence of various Th2 cytokines. IL-5, but not IL-13 or IL-25, primed bone marrow progenitor cells to differentiate into robust IL-4-producing cells. The majority of IL-4-producing cells induced by IL-5 were eosinophils. Importantly, IL-5 completely depended on STAT5 to promote IL-4-producing capacity in eosinophils. Thus, our study demonstrates that IL-5 functions as a potent factor that drives bone marrow progenitor cells into IL-4-producing eosinophils.
Cutting Edge: Critical Role for CD5 in Experimental Autoimmune Encephalomyelitis: Inhibition of Engagement Reverses Disease in Mice
Authors: Axtell Robert C. , Webb Matthew S. , Barnum Scott R. , Raman Chander
Published: April 2014

The induction phase of experimental autoimmune encephalomyelitis (EAE) in mice is T cell dependent and coreceptors that regulate T cell activation modulate disease development. We report here that mice lacking CD5, an important modulator of T cell activation, exhibit significantly delayed onset and decreased severity of EAE. The resistance to EAE in CD5−/− mice was not due to the inability of T cells to respond efficiently to stimulation with MOG35–55 but was associated with the presence of elevated frequency of apoptotic activated T cells in spleens and DLN. We also observed a net decrease in peripheral activated CD4+ T cells in CD5−/− spleens and DLN 10 days after immunization. We further show that in vivo blockade of CD5 engagement after induction of EAE by soluble CD5-Fc, a treatment that induces elimination of activated T cells, promoted recovery from EAE. Our studies indicate that CD5 regulates survival of activated T cells and provides a target for treatment of T cell-dependent autoimmune diseases such as multiple sclerosis.
CD4+CD25+ Cells Controlling a Pathogenic CD4 Response Inhibit Cytokine Differentiation, CXCR-3 Expression, and Tissue Invasion
Authors: Sarween Nadia , Chodos Anna , Raykundalia Chandra , Khan Mahmood , Abbas Abul K. , Walker Lucy S. K.
Published: April 2014

It is well established that CD4+CD25+ regulatory T cells (Tregs) inhibit autoimmune pathology. However, precisely how the behavior of disease-inducing T cells is altered by Tregs remains unclear. In this study we use a TCR transgenic model of diabetes to pinpoint how pathogenic CD4 T cells are modified by Tregs in vivo. We show that although Tregs only modestly inhibit CD4 cell expansion, they potently suppress tissue infiltration. This is associated with a failure of CD4 cells to differentiate into effector cells and to up-regulate the IFN-γ-dependent chemokine receptor CXCR-3, which confers the ability to respond to pancreatic islet-derived CXCL10. Our data support a model in which Tregs permit T cell activation, yet prohibit T cell differentiation and migration into Ag-bearing tissues.
Lymphocyte Development and Function in the Absence of Retinoic Acid-Related Orphan Receptor α
Authors: Dzhagalov Ivan , Giguère Vincent , He You-Wen
Published: April 2014

The orphan nuclear receptor, retinoid acid-related orphan receptor (ROR)α, is essential for the development of cerebellar Purkinje cells and bone tissue. RORα may also play a critical role in lymphocyte development and function because staggerer mice, a natural mutant strain with a disrupted expression of RORα, have reduced thymic and splenic cellularity. In this report, we analyzed the role of RORα in lymphocyte development by examining lymphoid compartments in RORα−/− mice and Rag-2−/− mice reconstituted with RORα−/− bone marrow. We found that T and B cell development was severely defective in RORα−/− mice, but not in Rag-2−/−/RORα−/− chimeric mice. We also analyzed cellular and humoral immune responses in Rag-2−/−/RORα−/− chimeric mice. Our results show that serum IgG levels were elevated in Rag-2−/−/RORα−/− chimeric mice after immunization with a T-dependent Ag compared with control chimeras. IFN-γ production by RORα−/− CD8+ T cells after TCR stimulation was also increased. Furthermore, RORα−/− mast cells and macrophages produced an increased amount of TNF-α and IL-6 upon activation. These results indicate that RORα indirectly regulates lymphocyte development by providing an appropriate microenvironment and controls immune responses by negatively regulating cytokine production in innate immune cells and lymphocytes.
Lipid Rafts Mediate Association of LFA-1 and CD3 and Formation of the Immunological Synapse of CTL
Authors: Marwali Muhammad Reza , MacLeod Matthew A. , Muzia David N. , Takei Fumio
Published: April 2014

Lipid rafts accumulate in the immunological synapse formed by an organized assembly of the TCR/CD3, LFA-1, and signaling molecules. However, the precise role of lipid rafts in the formation of the immunological synapse is unclear. In this study, we show that LFA-1 on CTL is constitutively active and mediates Ag-independent binding of CTL to target cells expressing its ligands. LFA-1 and CD3 on CTL, but not resting T cells, colocalize in lipid rafts. Binding of LFA-1 on CTL to targets initiates the formation of the immunological synapse, which is formed by LFA-1, CD3, and ganglioside GM1 distributed in the periphery of the cell contact site and cholesterol is more widely distributed. The formation of this synapse is Ag independent, but the recognition of Ag by the TCR induces accumulation of tyrosine phosphorylated proteins in the synapse as well as redistribution of the microtubule organization center toward the cell contact site. Our results suggest that LFA-1 recruits lipid rafts and the TCR/CD3 to the synapse, and facilitates efficient and rapid activation of CTL.
Caspase-8 Serves Both Apoptotic and Nonapoptotic Roles
Authors: Kang Tae-Bong , Ben-Moshe Tehila , Varfolomeev Eugene E. , Pewzner-Jung Yael , Yogev Nir , Jurewicz Anna , Waisman Ari , Brenner Ori , Haffner Rebecca , Gustafsson Erika , Ramakrishnan Parameswaran , Lapidot Tsvee , Wallach David
Published: April 2014

Knockout of caspase-8, a cysteine protease that participates in the signaling for cell death by receptors of the TNF/nerve growth factor family, is lethal to mice in utero. To explore tissue-specific roles of this enzyme, we established its conditional knockout using the Cre/loxP recombination system. Consistent with its role in cell death induction, deletion of caspase-8 in hepatocytes protected them from Fas-induced caspase activation and death. However, application of the conditional knockout approach to investigate the cause of death of caspase-8 knockout embryos revealed that this enzyme also serves cellular functions that are nonapoptotic. Its deletion in endothelial cells resulted in degeneration of the yolk sac vasculature and embryonal death due to circulatory failure. Caspase-8 deletion in bone-marrow cells resulted in arrest of hemopoietic progenitor functioning, and in cells of the myelomonocytic lineage, its deletion led to arrest of differentiation into macrophages and to cell death. Thus, besides participating in cell death induction by receptors of the TNF/nerve growth factor family, caspase-8, apparently independently of these receptors, also mediates nonapoptotic and perhaps even antiapoptotic activities.
Phosphatidylserine Regulates the Maturation of Human Dendritic Cells
Authors: Chen Xiao , Doffek Kara , Sugg Sonia L. , Shilyansky Joel
Published: April 2014

Phosphatidylserine (PS), which is exposed on the surface of apoptotic cells, has been implicated in immune regulation. However, the effects of PS on the maturation and function of dendritic cells (DCs), which play a central role in both immune activation and regulation, have not been described. Large unilamellar liposomes containing PS or phosphatidylcholine were used to model the plasma membrane phospholipid composition of apoptotic and live cells, respectively. PS liposomes inhibited the up-regulation of HLA-ABC, HLA-DR, CD80, CD86, CD40, and CD83, as well as the production of IL-12p70 by human DCs in response to LPS. PS did not affect DC viability directly but predisposed DCs to apoptosis in response to LPS. DCs exposed to PS had diminished capacity to stimulate allogeneic T cell proliferation and to activate IFN-γ-producing CD4+ T cells. Exogenous IL-12 restored IFN-γ production by CD4+ T cells. Furthermore, activated CTLs proliferated poorly to cognate Ag presented by DCs exposed to PS. Our findings suggest that PS exposure provides a sufficient signal to inhibit DC maturation and to modulate adaptive immune responses.
Bcl-2 Transduction Protects Human Endothelial Cell Synthetic Microvessel Grafts from Allogeneic T Cells In Vivo
Authors: Zheng Lian , Gibson Thomas F. , Schechner Jeffrey S. , Pober Jordan S. , Bothwell Alfred L. M.
Published: April 2014

T cell interactions with vascular endothelial cells (EC) are of central importance for immune surveillance of microbes and for pathological processes such as atherosclerosis, allograft rejection, and vasculitis. Animal (especially rodent) models incompletely predict human immune responses, in particular with regard to the immunological functions of EC, and in vitro models may not accurately reflect in vivo findings. In this study, we describe the development of an immunodeficient SCID/bg murine model combining a transplanted human synthetic microvascular bed with adoptive transfer of human T lymphocytes allogeneic to the cells of the graft that more fully recapitulates T cell responses in natural tissues. Using this model, we demonstrate that transduced Bcl-2 protein in the engrafted EC effectively prevents injury even as it enhances T cell graft infiltration and replication.
Characterization of the Systemic Loss of Dendritic Cells in Murine Lymph Nodes During Polymicrobial Sepsis
Authors: Efron Philip A. , Martins Antonio , Minnich Douglas , Tinsley Kevin , Ungaro Ricardo , Bahjat Frances R. , Hotchkiss Richard , Clare-Salzler Michael , Moldawer Lyle L.
Published: April 2014

Dendritic cells (DCs) play a key role in critical illness and are depleted in spleens from septic patients and mice. To date, few studies have characterized the systemic effect of sepsis on DC populations in lymphoid tissues. We analyzed the phenotype of DCs and Th cells present in the local (mesenteric) and distant (inguinal and popliteal) lymph nodes of mice with induced polymicrobial sepsis (cecal ligation and puncture). Flow cytometry and immunohistochemical staining demonstrated that there was a significant local (mesenteric nodes) and partial systemic (inguinal, but not popliteal nodes) loss of DCs from lymph nodes in septic mice, and that this process was associated with increased apoptosis. This sepsis-induced loss of DCs occurred after CD3+CD4+ T cell activation and loss in the lymph nodes, and the loss of DCs was not preceded by any sustained increase in their maturation status. In addition, there was no preferential loss of either mature/activated (MHCIIhigh/CD86high) or immature (MHCIIlow/CD86low) DCs during sepsis. However, there was a preferential loss of CD8+ DCs in the local and distant lymph nodes. The loss of DCs in lymphoid tissue, particularly CD8+ lymphoid-derived DCs, may contribute to the alterations in acquired immune status that frequently accompany sepsis.
Strong and Durable TCR Clustering at the T/Dendritic Cell Immune Synapse Is Not Required for NFAT Activation and IFN-γ Production in Human CD4+ T Cells
Authors: Blanchard Nicolas , Decraene Maud , Yang Kun , Miro-Mur Francesc , Amigorena Sebastian , Hivroz Claire
Published: April 2014

The exact function of TCR clustering and organized macromolecular patterns at the immune synapse between APCs and T lymphocytes is unclear. Using human immature or mature dendritic cells (DCs) and autologous CD4+ effector T cells, we demonstrate that, within a given conjugate, mature DCs induce strong and long-lasting TCR clustering and protein kinase C-θ translocation in a superantigen dose-dependent manner. Moreover, mature DCs promote CD43 exclusion in a dose-independent manner. In contrast, immature DCs are less potent at inducing these molecular rearrangements. Using these models to correlate T cell functions with the frequency, the intensity, and the duration of TCR clustering, we show, in Jurkat T cells, that weak and transient TCR clustering is sufficient to promote TCR down-modulation, protein kinase C-θ translocation at the synapse, and substantial NFAT transcriptional activation. Moreover, we show, in CD4+ T cell blasts, that strong TCR clustering is required for neither TCR down-modulation nor optimal IFN-γ production. Together, our results demonstrate that some CD4+ functional responses, such as cytokine production, are independent of central supramolecular activation cluster formation.
Diabetes Incidence Is Unaltered in Glutamate Decarboxylase 65-Specific TCR Retrogenic Nonobese Diabetic Mice: Generation by Retroviral-Mediated Stem Cell Gene Transfer
Authors: Arnold Paula Y. , Burton Amanda R. , Vignali Dario A. A.
Published: April 2014

TCR transgenic mice are valuable tools for dissecting the role of autoantigen-specific T cells in the pathogenesis of type 1 diabetes but are time-consuming to generate and backcross onto congenic strains. To circumvent these limitations, we developed a new approach to rapidly generate mice expressing TCR using retroviral-mediated stem cell gene transfer and a novel picornavirus-like 2A peptide to link the TCR α- and β-chains in a single retroviral vector. We refer to these as retrogenic (Rg) mice to avoid confusion with conventional transgenic mice. Our approach was validated by demonstrating that Rg nonobese diabetic (NOD)-scid mice expressing the diabetogenic TCRs, BDC2.5 and 4.1, generate clonotype-positive T cells and develop diabetes. We then expressed three TCR specific for either glutamate decarboxylase (GAD) 206–220 or GAD 524–538 or for hen egg lysozyme 11–25 as a control in NOD, NOD-scid, and B6.H2g7 mice. Although T cells from these TCR Rg mice responded to their respective Ag in vitro, the GAD-specific T cells exhibited a naive, resting phenotype in vivo. However, T cells from Rg mice challenged with Ag in vivo became activated and developed into memory cells. Neither of the GAD-reactive TCR accelerated or protected mice from diabetes, nor did activated T cells transfer or protect against diabetes in NOD-scid recipients, suggesting that GAD may not be a primary target for diabetogenic T cells. Generation of autoantigen-specific TCR Rg mice represents a powerful approach for the analysis of a wide variety of autoantigens.