bluuebunny/crossref_metadata_2025 huggingface dataset:
Herpes Simplex Virus Infection of Human Dendritic Cells Induces Apoptosis and Allows Cross-Presentation via Uninfected Dendritic Cells
Authors: Bosnjak Lidija , Miranda-Saksena Monica , Koelle David M. , Boadle Ross A. , Jones Cheryl A. , Cunningham Anthony L.
Published: April 2014

HSV efficiently infects dendritic cells (DCs) in their immature state and induces down-regulation of costimulatory and adhesion molecules. As in mice, HSV infection of human DCs also leads to their rapid and progressive apoptosis, and we show that both early and late viral proteins contribute to its induction. Because topical HSV infection is confined to the epidermis, Langerhans cells are expected to be the major APCs in draining lymph nodes. However, recent observations in murine models show T cell activation to be mediated by nonepidermal DC subsets, suggesting cross-presentation of viral Ag. In this study we provide an explanation for this phenomenon, demonstrating that HSV-infected apoptotic DCs are readily phagocytosed by uninfected bystander DCs, which, in turn, stimulate virus-specific CD8+ T cell clones.
Induction of Cell Cycle Arrest in Lymphocytes by Actinobacillus actinomycetemcomitans Cytolethal Distending Toxin Requires Three Subunits for Maximum Activity
Authors: Shenker Bruce J. , Besack Dave , McKay Terry , Pankoski Lisa , Zekavat Ali , Demuth Donald R.
Published: April 2014

We have previously shown that Actinobacillus actinomycetemcomitans produces an immunosuppressive factor encoded by the cytolethal distending toxin (cdt)B gene. In this study, we used rCdt peptides to study the contribution of each subunit to toxin activity. As previously reported, CdtB is the only Cdt subunit that is capable of inducing cell cycle arrest by itself. Although CdtA and CdtC do not exhibit activity alone, each subunit is able to significantly enhance the ability of CdtB to induce G2 arrest in Jurkat cells; these effects were dependent upon protein concentration. Moreover, the combined addition of both CdtA and CdtC increased the ED50 for CdtB >7000-fold. In another series of experiments, we demonstrate that the three Cdt peptides are able to form a functional toxin unit on the cell surface. However, these interactions first require that a complex forms between the CdtA and CdtC subunits, indicating that these peptides are required for interaction between the cell and the holotoxin. This conclusion is further supported by experiments in which both Jurkat cells and normal human lymphocytes were protected from Cdt holotoxin-induced G2 arrest by pre-exposure to CdtA and CdtC. Finally, we have used optical biosensor technology to show that CdtA and CdtC have a strong affinity for one another (10−7 M). Furthermore, although CdtB is unable to bind to either CdtA or CdtC alone, it is capable of forming a stable complex with CdtA/CdtC. The implications of our results with respect to the function and structure of the Cdt holotoxin are discussed.
Poly(ADP-Ribose) Polymerase-1 Promotes Microglial Activation, Proliferation, and Matrix Metalloproteinase-9-Mediated Neuron Death
Authors: Kauppinen Tiina M. , Swanson Raymond A.
Published: April 2014

Activated microglia contribute to cell death in ischemic and neurodegenerative disorders of the CNS. Microglial activation is regulated in part by NF-κB, and the nuclear enzyme poly(ADP-ribose) polymerase-1 (PARP-1) enhances NF-κB binding to DNA. In this study, the role of PARP-1 in microglia-mediated neurotoxicity was assessed using microglia from wild-type (wt) and PARP-1−/− mice. Cultured microglia were incubated with TNF-α, a cytokine that is up-regulated in many neurological disorders. When stimulated with TNF-α, wt microglia proliferated, underwent morphological changes characteristic of activation, and killed neurons placed in coculture. The effects of TNF-α were markedly attenuated both in PARP-1−/− microglia and in wt microglia treated with the PARP enzymatic inhibitor 3,4-dihydro-5-[4-(1-piperidinyl)butoxy]-1(2h)-isoquinolinone. These effects were also blocked by (E)-3-(4-methylphenylsulfonyl)-2-propenenenitrile, which inhibits translocation of NF-κB to the nucleus. TNF-α also up-regulated microglial release of matrix metalloproteinase-9 (MMP-9), an enzyme with potential neurotoxic properties that is transcriptionally regulated by NF-κB. This up-regulation was blocked in PARP-1−/− microglia and in wt microglia by the PARP inhibitor 3,4-dihydro-5-[4-(1-piperidinyl)butoxy]-1(2h)-isoquinolinone. Microglia from MMP-9−/− mice were used to evaluate the contribution of MMP-9 to microglial neurotoxicity. MMP-9−/− microglia treated with TNF-α showed substantially reduced neurotoxicity relative to the wt microglia. TNF-α-stimulated wt microglia treated with the MMP inhibitor ilomastat also showed reduced neurotoxicity. These findings suggest that PARP-1 activation is required for both TNF-α-induced microglial activation and the neurotoxicity resulting from TNF-α-induced MMP-9 release.
Regulation of S100A8 by Glucocorticoids
Authors: Hsu Kenneth , Passey Robert J. , Endoh Yasumi , Rahimi Farid , Youssef Peter , Yen Tina , Geczy Carolyn L.
Published: April 2014

S100A8 (A8) has roles in inflammation, differentiation and development and is associated with oxidative defense. Murine A8 (mA8) is up-regulated in macrophages, fibroblasts, and microvascular endothelial cells by LPS. Glucocorticoids (GCs) amplified LPS-induced mA8 in these cells. Relative to stimulation by LPS, GCs increased mA8 gene transcription and mRNA half-life. Enhancement required new protein synthesis, IL-10 and products of the cyclooxygenase-2 pathway, and both ERK1/2 and p38 MAPK. Protein kinase A positively and protein kinase C negatively regulated this process. Promoter analysis indicated element(s) essential for LPS and dexamethasone enhancement colocated within the region −178 to 0 bp. In the absence of glucocorticoid response elements, NF1 motif at −58 is a candidate for mediation of enhancement. Gel shift analysis detected no differences between LPS- and LPS/dexamethasone-treated complexes within this region. GCs increased constitutive levels of A8 and S100A9 (A9) mRNA in human monocytes. The synovial membrane of rheumatoid patients treated with high dose i.v. methylprednisolone contained higher numbers of A8/A9-positive macrophages than pre- or posttreatment samples. Results support the proposal that A8 has anti-inflammatory properties that may be independent of hetero-complex formation with A9 and may also enable localized defense in the absence of overriding deleterious host responses.
Suppression of Autoimmune Retinal Disease by Lovastatin Does Not Require Th2 Cytokine Induction
Authors: Gegg Matthew E. , Harry Rachel , Hankey Deborah , Zambarakji Hadi , Pryce Gareth , Baker David , Adamson Peter , Calder Virginia , Greenwood John
Published: April 2014

Intraocular inflammatory diseases are a common cause of severe visual impairment and blindness. In an acute mouse model of autoimmune retinal disease, we demonstrate that treatment with the 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor, lovastatin, suppresses clinical ocular pathology, retinal vascular leakage, and leukocytic infiltration into the retina. Efficacy was reversed by coadministration of mevalonolactone, the downstream product of 3-hydroxy-3-methylglutaryl coenzyme A reductase, but not by squalene, which is distal to isoprenoid pyrophosphate metabolites within the cholesterol biosynthetic pathway. Lovastatin treatment (20 mg/kg/day i.p.) over 7 days, which resulted in plasma lovastatin hydroxyacid concentrations of 0.098 ± 0.03 μM, did not induce splenocyte Th2 cytokine production but did cause a small reduction in Ag-induced T cell proliferation and a decrease in the production of IFN-γ and IL-10. Thus, it is possible to dissociate the therapeutic effect of statins in experimental autoimmune uveitic mice from their activity on the Th1/Th2 balance. Statins inhibit isoprenoid pyrophosphate synthesis, precursors required for the prenylation and posttranslational activation of Rho GTPase, a key molecule in the endothelial ICAM-1-mediated pathway that facilitates lymphocyte migration. Consistent with inhibition of leukocyte infiltration in vivo, lovastatin treatment of retinal endothelial cell monolayers in vitro leads to inhibition of lymphocyte transmigration, which may, in part, account for drug efficacy. Unlike lovastatin, atorvastatin treatment showed little efficacy in retinal inflammatory disease despite showing significant clinical benefit in experimental autoimmune encephalomyelitis. These data highlight the potential differential activity of statins in different inflammatory conditions and their possible therapeutic use for the treatment of human posterior uveitis.
Conditional Macrophage Ablation Demonstrates That Resident Macrophages Initiate Acute Peritoneal Inflammation
Authors: Cailhier Jean Francois , Partolina Marina , Vuthoori Srilatha , Wu Shengji , Ko Kyung , Watson Simon , Savill John , Hughes Jeremy , Lang Richard A.
Published: April 2014

The role played by resident macrophages (Mφ) in the initiation of peritoneal inflammation is currently unclear. We have used a conditional Mφ ablation strategy to determine the role of resident peritoneal Mφ in the regulation of neutrophil (PMN) recruitment in experimental peritonitis. We developed a novel conditional Mφ ablation transgenic mouse (designated CD11bDTR) based upon CD11b promoter-mediated expression of the human diphtheria toxin (DT) receptor. The murine DT receptor binds DT poorly such that expression of the human receptor confers toxin sensitivity. Intraperitoneal injection of minute (nanogram) doses of DT results in rapid and marked ablation of F4/80-positive Mφ populations in the peritoneum as well as the kidney, and ovary. In experimental peritonitis, resident Mφ ablation resulted in a dramatic attenuation of PMN infiltration that was rescued by the adoptive transfer of resident nontransgenic Mφ. Attenuation of PMN infiltration was associated with diminished CXC chemokine production at 1 h. These studies indicate a key role for resident peritoneal Mφ in sensing perturbation to the peritoneal microenvironment and regulating PMN infiltration.
Decay-Accelerating Factor (CD55) Is Expressed by Neurons in Response to Chronic but Not Acute Autoimmune Central Nervous System Inflammation Associated with Complement Activation
Authors: van Beek Johan , van Meurs Marjan , ‘t Hart Bert A. , Brok Herbert P. M. , Neal Jim W. , Chatagner Alexandra , Harris Claire L. , Omidvar Nader , Morgan B. Paul , Laman Jon D. , Gasque Philippe
Published: April 2014

There is compelling evidence that a unique innate immune response in the CNS plays a critical role in host defense and clearance of toxic cell debris. Although complement has been implicated in neuronal impairment, axonal loss, and demyelination, some preliminary evidence suggests that the initial insult consequently activates surrounding cells to signal neuroprotective activities. Using two different models of experimental autoimmune encephalomyelitis, we herein demonstrate selective C1q complement activation on neuron cell bodies and axons. Interestingly, in brains with chronic but not acute experimental autoimmune encephalomyelitis, C3b opsonization of neuronal cell bodies and axons was consistently associated with robust neuronal expression of one of the most effective complement regulators, decay-accelerating factor (CD55). In contrast, levels of other complement inhibitors, complement receptor 1 (CD35), membrane cofactor protein (CD46), and CD59 were largely unaffected on neurons and reactive glial cells in both conditions. In vitro, we found that proinflammatory stimuli (cytokines and sublytic doses of complement) failed to up-regulate CD55 expression on cultured IMR32 neuronal cells. Interestingly, overexpression of GPI-anchored CD55 on IMR32 was capable of modulating raft-associated protein kinase activities without affecting MAPK activities and neuronal apoptosis. Critically, ectopic expression of decay-accelerating factor conferred strong protection of neurons against complement attack (opsonization and lysis). We conclude that increased CD55 expression by neurons may represent a key protective signaling mechanism mobilized by brain cells to withstand complement activation and to survive within an inflammatory site.
Cutting Edge: Type I IFNs Provide a Third Signal to CD8 T Cells to Stimulate Clonal Expansion and Differentiation
Authors: Curtsinger Julie M. , Valenzuela Javier O. , Agarwal Pujya , Lins Debra , Mescher Matthew F.
Published: April 2014

In this study, we show that IFN-αβ can have a direct role in linking innate and adaptive responses by providing the “third signal” needed by naive CD8 T cells responding to Ag and costimulatory ligands. Stimulation of CD8 T cells in the absence of a third signal leads to proliferation, but clonal expansion is limited by poor survival and effector functions do not develop. We show that IFN-αβ can provide the third signal directly to CD8 T cells via a STAT4-dependent pathway to stimulate survival, development of cytolytic function, and production of IFN-γ. Provision of the third signal by either IFN-αβ or IL-12 results in regulation of the expression of a number of genes, including several that encode proteins critical for effector function.
Generation of High-Affinity Antibody against T Cell-Dependent Antigen in the Ganp Gene-Transgenic Mouse
Authors: Sakaguchi Nobuo , Kimura Tetsuya , Matsushita Shuzo , Fujimura Satoru , Shibata Junji , Araki Masatake , Sakamoto Tamami , Minoda Chiemi , Kuwahara Kazuhiko
Published: April 2014

Generation of high-affinity Ab is impaired in mice lacking germinal center-associated DNA primase (GANP) in B cells. In this study, we examined the effect of its overexpression in ganp transgenic C57BL/6 mice (GanpTg). GanpTg displayed normal phenotype in B cell development, serum Ig levels, and responses against T cell-independent Ag; however, it generated the Ab with much higher affinity against nitrophenyl-chicken gammaglobulin in comparison with C57BL/6. To further examine the affinity increase, we established hybridomas producing high-affinity mAbs and compared their affinities using BIAcore. C57BL/6 generated high-affinity anti-nitrophenyl mAbs (KD ∼ 2.50 × 10−7 M) of IgG1/λ1 and contained the VH186.2 region with W33L mutation. GanpTg generated much higher affinity (KD > 1.57 × 10−9 M) by usage of VH186.2 as well as noncanonical VH7183 regions. GanpTg also generated exceptionally high-affinity anti-HIV-1 (V3 peptide) mAbs (KD > 9.90 × 10−11 M) with neutralizing activity. These results demonstrated that GANP is involved in V region alteration generating high-affinity Ab.
Regulation of Highly Cytokinergic IgE-Induced Mast Cell Adhesion by Src, Syk, Tec, and Protein Kinase C Family Kinases
Authors: Kitaura Jiro , Eto Koji , Kinoshita Tatsuya , Kawakami Yuko , Leitges Michael , Lowell Clifford A. , Kawakami Toshiaki
Published: April 2014

Mast cells play a critical role in IgE-dependent immediate hypersensitivity. Recent studies have shown that, contrary to the traditional view, binding of monomeric IgE to FcεRI results in a number of biological outcomes in mast cells, including survival. However, IgE molecules display heterogeneity in inducing cytokine production; highly cytokinergic (HC) IgEs cause extensive FcεRI aggregation, which leads to potent enhancement of survival and other activation events, whereas poorly cytokinergic (PC) IgEs can do so inefficiently. The present study demonstrates that HC, but not PC, IgEs can efficiently induce adhesion and spreading of mouse mast cells on fibronectin-coated plates in slow and sustained kinetics. HC IgE-induced adhesion through β1 and β7 integrins promotes survival, IL-6 production, and DNA synthesis. Importantly, we have identified Lyn and Syk as requisite tyrosine kinases and Hck, Btk, and protein kinase C θ as contributory kinases in HC IgE-induced adhesion and spreading, whereas protein kinase C ε plays a negative role. Consistent with these results, Lyn, Syk, and Btk are activated in HC IgE-stimulated cells in a slower but more sustained manner, compared with cells stimulated with IgE and Ag. Thus, binding of HC IgEs to FcεRI induces adhesion of mast cells to fibronectin by modulating cellular activation signals in a unique fashion.
Active Tolerance Induction and Prevention of Autoimmune Diabetes by Immunogene Therapy Using Recombinant Adenoassociated Virus Expressing Glutamic Acid Decarboxylase 65 Peptide GAD500–585
Authors: Han Gencheng , Li Yan , Wang Jianan , Wang Renxi , Chen Guojiang , Song Lun , Xu Ruonan , Yu Ming , Wu Xiaobing , Qian Jiahua , Shen Beifen
Published: April 2014

Tolerance induction of autoreactive T cells against pancreatic β cell-specific autoantigens such as glutamic acid decarboxylase 65 (GAD65) and insulin has been attempted as a method to prevent autoimmune diabetes. In this study, we investigate whether adenoassociated virus (AAV) gene delivery of multiple immunodominant epitopes expressing GAD500–585 could induce potent immune tolerance and persistently suppress autoimmune diabetes in NOD mice. A single muscle injection of 7-wk-old female NOD mice with rAAV/GAD500–585 (3 × 1011 IU/mouse) quantitatively reduced pancreatic insulitis and efficiently prevented the development of overt type I diabetes. This prevention was marked by the inactivation of GAD500–585-responsive T lymphocytes, the enhanced GAD500–585-specific Th2 response (characterized by increased IL-4, IL-10 production, and decreased IFN-γ production; especially elevated anti-GAD500–585 IgG1 titer; and relatively unchanged anti-GAD500–585 IgG2b titer), the increased secretion of TGF-β, and the production of protective regulatory cells. Our studies also revealed that peptides 509–528, 570–585, and 554–546 in the region of GAD500–585 played important roles in rAAV/GAD500–585 immunization-induced immune tolerance. These data indicate that using AAV, a vector with advantage for therapeutic gene delivery, to transfer autoantigen peptide GAD500–585, can induce immunological tolerance through active suppression of effector T cells and prevent type I diabetes in NOD mice.
A Sexual Dimorphism in Intrathymic Sialylation Survey Is Revealed by thetrans-Sialidase fromTrypanosoma cruzi
Authors: Mucci Juan , Mocetti Esteban , Leguizamón María Susana , Campetella Oscar
Published: April 2014

Sialylation is emerging as an important issue in developing thymocytes and is considered among the most significant cell surface modifications, although its physiologic relevance is far from being completely understood. It is regulated by the concerted expression of sialyl transferases along thymocyte development. After in vivo administration of trans-sialidase, a virulence factor from the American trypanosomatid Trypanosoma cruzi that directly transfers the sialyl residue among macromolecules, we found that the alteration of the sialylation pattern induces thymocyte apoptosis inside the “nurse cell complex.” This suggests a glycosylation survey in the development of the T cell compartment. In this study, we report that this thymocyte apoptosis mechanism requires the presence of androgens. No increment in apoptosis was recorded after trans-sialidase administration in females or in antiandrogen-treated, gonadectomized, or androgen receptor mutant male mice. The androgen receptor presence was required only in the thymic epithelial cells as determined by bone marrow chimeric mouse approaches. The presence of the CD43 surface mucin, a molecule with a still undefined function in thymocytes, was another absolute requirement. The trans-sialidase-induced apoptosis proceeds through the TNF-α receptor 1 deathly signaling leading to the activation of the caspase 3. Accordingly, the production of the cytokine was increased in thymocytes. The ability of males to delete thymocytes altered in their sialylation pattern reveals a sexual dimorphism in the glycosylation survey during the development of the T cell compartment that might be related to the known differences in the immune response among sexes.
Signals from CD28 Induce Stable Epigenetic Modification of the IL-2 Promoter
Authors: Thomas Rajan M. , Gao Ling , Wells Andrew D.
Published: April 2014

CD28 costimulation controls multiple aspects of T cell function, including the expression of proinflammatory cytokine genes. One of these genes encodes IL-2, a growth factor that influences T cell proliferation, survival, and differentiation. Antigenic signaling in the absence of CD28 costimulation leads to anergy, a mechanism of tolerance that renders CD4+ T cells unable to produce IL-2. The molecular mechanisms by which CD28 costimulatory signals induce gene expression are not fully understood. In eukaryotic cells, the expression of many genes is influenced by their physical structure at the level of DNA methylation and local chromatin remodeling. To address whether these epigenetic mechanisms are operative during CD28-dependent gene expression in CD4+ T cells, we compared cytosine methylation and chromatin structure at the IL-2 locus in fully activated CD4+ effector T cells and CD4+ T cells rendered anergic by TCR ligation in the absence of CD28 costimulation. Costimulation through CD28 led to marked, stable histone acetylation and loss of cytosine methylation at the IL-2 promoter/enhancer. This was accompanied by extensive remodeling of the chromatin in this region to a structure highly accessible to DNA binding proteins. Conversely, TCR activation in the absence of CD28 costimulation was not sufficient to promote histone acetylation or cytosine demethylation, and the IL-2 promoter/enhancer in anergic cells remained completely inaccessible. These data suggest that CD28 may function through epigenetic mechanisms to promote CD4+ T cell responses.
T Cell-Mediated Delay of Spontaneous Mammary Tumor Onset: Increased Efficacy with In Vivo versus In Vitro Activation
Authors: O’Mara Leigh A. , Norian Lyse A. , Kreamalmeyer Darren , White J. Michael , Allen Paul M.
Published: April 2014

Peripheral tolerance to shared Ags expressed on both tumors and normal self-tissues presents a major barrier to T cell-based immunotherapy as a treatment for cancer. To assess the activity of tumor-specific T cells against spontaneously arising carcinomas in the context of shared Ag expression, we developed a model system whereby an identified tumor Ag, tumor ERK (tERK), is expressed transgenically on both normal mammary tissue and spontaneous mammary carcinomas. Transfer of in vitro-activated, tERK-specific DUC18 T cells delayed spontaneous tumor development in tERK-expressing mice when T cells were given before the development of palpable carcinomas. However, antitumor activity mediated by in vitro-activated DUC18 T cells, as measured by responsiveness against a transplanted tERK-expressing fibrosarcoma challenge, was lost within days of transfer. This loss was due to expression of tERK as a self-Ag on normal tissues and was independent of the presence of mammary tumors. In contrast, transferred naive DUC18 T cells maintained a long-term protective function in tERK-expressing mice. Ten-fold fewer naive T cells activated in vivo were able to replicate the delay in spontaneous tumor development achieved by in vitro-activated T cells. These results are in contrast to our earlier studies using transplanted tumors alone, in which in vitro-activated DUC18 T cells were more efficacious than naive DUC18 T cells and highlight the need to perform tumor studies in the presence of tumor Ag expression on normal self-tissue.
γδ T Cells Regulate the Extent and Duration of Inflammation in the Central Nervous System by a Fas Ligand-Dependent Mechanism
Authors: Ponomarev Eugene D. , Dittel Bonnie N.
Published: April 2014

γδ T cells have been shown to regulate immune responses associated with inflammation, but the mechanism of this regulation is largely unknown. Using the experimental autoimmune encephalomyelitis (EAE) model of the human CNS autoimmune disease multiple sclerosis, we demonstrate that γδ T cells are important regulators of CNS inflammation. This was shown using γδ T cell-deficient mice that were unable to recover from EAE. The chronic disease was accompanied by a prolonged presence of both macrophages and lymphocytes in the CNS. This extended inflammatory response was due to alterations in both cell proliferation and death. In mice lacking γδ T cells, proliferation of encephalitogenic T cells was 3-fold higher, and caspase activity, indicating apoptosis, was 2-fold lower compared with those in control mice recovering from EAE. γδ T cell-deficient mice reconstituted with wild-type γδ T cells recovered from EAE and resolved inflammation in the CNS, whereas mice reconstituted with Fas ligand-dysfunctional γδ T cells did not. Thus, γδ T cells regulate both inflammation in the CNS and disease recovery via Fas/Fas ligand-induced apoptosis of encephalitogenic T cells, and a quick resolution of inflammation in the CNS is essential to prevent permanent damage to the CNS resulting in chronic disease.
IL-12-Independent LIGHT Signaling Enhances MHC Class II Disparate CD4+ T Cell Alloproliferation, IFN-γ Responses, and Intestinal Graft-versus-Host Disease
Authors: Brown Geri R. , Lee Edward L. , El-Hayek Jihad , Kintner Katherine , Luck Cheryl
Published: April 2014

Inhibition of LIGHT (a cellular ligand for herpes virus entry mediator and lymphotoxin receptor)/herpes simplex virus entry mediator (HVEM) and LIGHT/lymphotoxin β receptor (LTβR) interactions decreases mortality in MHC class I and II disparate graft-vs-host disease (GVHD). The present studies assessed the effects of these interactions on the generation of CD4+ T cell alloresponses in MHC class II-disparate MLC and GVHD. An inhibitor protein of LIGHT and LTαβ2 (LTβR-Ig) and an inhibitor protein of LIGHT (HVEM-Ig) caused similar decreases in alloresponses of control B6 or B6.129S1-IL12rb2tm1Jm (B6.IL12R−/−) spleen cells (SpC) in a MHC class II-disparate MLC. GVHD-induced wasting disease in MHC class II-disparate recipients of B6 CD4+ SpC who received either the LTβR-Ig-encoding adenovirus (LTβR-Ig Adv; 13.1 ± 10.9%; n = 10; p = 0.0004) or the HVEM-Ig-encoding adenovirus (HVEM-Ig Adv; 16.4 ± 9.9%; n = 13; p = 0.0008) was significantly reduced compared with that in recipients of a control adenovirus (30.4 ± 8.8%; n = 13). Furthermore, gut GVHD histologic scores of recipients of B6 CD4+ SpC who received the LTβR-Ig Adv (0.8 ± 0.8; n = 5; p = 0.0007) or the HVEM-Ig Adv (1.4 ± 0.5; n = 5; p = 0.008) were reduced compared with scores of recipients of a control adenovirus (2.5 ± 0.75; n = 11). In the intestine, both LTβR-Ig Adv and HVEM-Ig Adv decreased CD4+ T cells (0.35 ± 0.4 × 106 (n = 6) vs 0.36 ± 0.02 × 106 (n = 9); p = 0.03 and p = 0.007) compared with control adenovirus (0.86 ± 0.42 × 106; n = 9). LIGHT is critical for optimal CD4+ T cell alloresponses in MHC class II-disparate MLC and GVHD.
Macrophage Colony-Stimulating Factor Drives Cord Blood Monocyte Differentiation into IL-10highIL-12absent Dendritic Cells with Tolerogenic Potential
Authors: Li Geling , Kim Young-June , Broxmeyer Hal E.
Published: April 2014

Immature dendritic cells (DCs) induce tolerance and mature DCs induce inflammatory immune responses. However, the likelihood of maturation of immature DCs in vivo limits its potential application for suppression of unwanted immune reactions in vivo. The aim of this study was to generate DCs with anti-inflammatory properties in both the immature and mature states. GM-CSF combined with IL-4 drives monocyte differentiation into DCs. As M-CSF is a critical cytokine in development of the monocytic lineage and its level is dramatically elevated in immunosuppressive conditions, we investigated whether M-CSF could replace GM-CSF and generate DCs with distinct functions from umbilical cord blood monocytes. Highly purified umbilical cord blood monocytes cultured with M-CSF and IL-4, in a GM-CSF-independent fashion, differentiated into IL-10highIL-12absent cells with a DC phenotype (termed M-DC). Single time stimulation with immature DCs (both M-DCs and DCs) derived from cord blood induced hyporesponsive and regulatory CD4+ T cells. In contrast to mature DCs, mature M-DCs induced decreased Th1 differentiation and proliferation of naive CD4+ T cells in both primary and secondary allogeneic MLR and showed tolerogenic potential. These results demonstrate an unrecognized role for M-CSF in alternative differentiation of monocytes into anti-inflammatory M-DCs and suggest that M-CSF-induced DCs may be of use for suppressing unwanted immune responses.
Pattern of Kvβ Subunit Expression in Macrophages Depends upon Proliferation and the Mode of Activation
Authors: Vicente Rubén , Escalada Artur , Soler Concepció , Grande Maribel , Celada Antonio , Tamkun Michael M. , Solsona Carles , Felipe Antonio
Published: April 2014

Voltage-dependent potassium channels (Kv) in leukocytes are involved in the immune response. In bone marrow-derived macrophages (BMDM), proliferation and activation induce delayed rectifier K+ currents, generated by Kv1.3, via transcriptional, translational, and posttranslational controls. Furthermore, modulatory Kvβ subunits coassociate with Kvα subunits, increasing channel diversity and function. In this study we have identified Kvβ subunits in mouse BMDM, studied their regulation during proliferation and activation, and analyzed K+ current parameters influenced by these proteins. BMDM express all isoforms of Kvβ1 (Kvβ1.1, Kvβ1.2, and Kvβ1.3) and Kvβ2 (Kvβ2.1), but not Kvβ4, the alternatively spliced murine Kvβ3 variant. M-CSF-dependent proliferation induced all Kvβ isoforms. However, LPS- and TNF-α-induced activation differentially regulated these subunits. Although LPS increased Kvβ1.3, reduced Kvβ1.2, and maintained Kvβ1.1 mRNA levels constant, TNF-α up-regulated Kvβ1.1, down-regulated Kvβ1.2, and left Kvβ1.3 expression unchanged. Moreover, in contrast to TNF-α, M-CSF- and LPS- up-regulated Kvβ2.1. K+ currents from M-CSF- and LPS-stimulated BMDM exhibited faster inactivation, whereas TNF-α increased τ values. Although in M-CSF-stimulated cells the half-inactivation voltage shifted to more positive potentials, the incubation with LPS and TNF-α resulted in a hyperpolarizing displacement similar to that in resting BMDM. Furthermore, activation time constants of K+ currents and the kinetics of the tail currents were different depending upon the mode of activation. Our results indicate that differential Kvβ expression modifies the electrical properties of Kv in BMDM, dependent upon proliferation and the mode of activation. This could determine physiologically appropriate surface channel complexes, allowing for greater flexibility in the precise regulation of the immune response.
A Role for SATB1, a Nuclear Matrix Association Region-Binding Protein, in the Development of CD8SP Thymocytes and Peripheral T Lymphocytes
Authors: Nie Hui , Maika Shanna D. , Tucker Philip W. , Gottlieb Paul D.
Published: April 2014

Studies have suggested that binding of the SATB1 protein to L2a, a matrix association region located 4.5 kb 5′ to the mouse CD8α gene, positively affects CD8 expression in T cells. Therefore, experiments were performed to determine the effect on T cell development of reduced expression of SATB1. Because homozygous SATB1-null mice do not survive to adulthood due to nonthymus autonomous defects, mice were produced that were homozygous for a T cell-specific SATB1-antisense transgene and heterozygous for a SATB1-null allele. Thymic SATB1 protein was reduced significantly in these mice, and the major cellular phenotype observed was a significant reduction in the percentage of CD8SP T cells in thymus, spleen, and lymph nodes. Mice were smaller than wild type but generally healthy, and besides a general reduction in cellularity and a slight increase in surface CD3 expression on CD8SP thymocytes, the composition of the thymus was similar to wild type. The reduction in thymic SATB1 does not lead to the variegated expression of CD8-negative single positive thymocytes seen upon deletion of several regulatory elements and suggested by others to reflect failure to activate the CD8 locus. Thus, the present results point to an essential role for SATB1 late in the development and maturation of CD8SP T cells.
Dysfunction of Simian Immunodeficiency Virus/Simian Human Immunodeficiency Virus-Induced IL-2 Expression by Central Memory CD4+ T Lymphocytes
Authors: Sun Yue , Schmitz Jörn E. , Acierno Paula M. , Santra Sampa , Subbramanian Ramu A. , Barouch Dan H. , Gorgone Darci A. , Lifton Michelle A. , Beaudry Kristin R. , Manson Kelledy , Philippon Valerie , Xu Ling , Maecker Holden T. , Mascola John R. , Panicali Dennis , Nabel Gary J. , Letvin Norman L.
Published: April 2014

Production of IL-2 and IFN-γ by CD4+ T lymphocytes is important for the maintenance of a functional immune system in infected individuals. In the present study, we assessed the cytokine production profiles of functionally distinct subsets of CD4+ T lymphocytes in rhesus monkeys infected with pathogenic or attenuated SIV/simian human immunodeficiency virus (SHIV) isolates, and these responses were compared with those in vaccinated monkeys that were protected from immunodeficiency following pathogenic SHIV challenge. We observed that preserved central memory CD4+ T lymphocyte production of SIV/SHIV-induced IL-2 was associated with disease protection following primate lentivirus infection. Persisting clinical protection in vaccinated and challenged monkeys is thus correlated with a preserved capacity of the peripheral blood central memory CD4+ T cells to express this important immunomodulatory cytokine.
IL-6 Increases Primed Cell Expansion and Survival
Authors: Rochman Irina , Paul William E. , Ben-Sasson S. Z.
Published: April 2014

Cytochrome c-specific CD4 T cells from transgenic donors transferred to syngeneic B10.A mice expand more vigorously upon immunization if exogenous IL-6 is provided during the initial phase of immunization. The resultant increase in the frequency and number of Ag-specific cells is observed in the blood, lymph nodes, spleen, liver, and lung and persists for at least 3 mo. Treatment of immunized recipients with anti-IL-6 or use of IL-6 knockout recipients reduced the frequency of Ag-specific CD4 T cells during a comparable period, indicating that IL-6 is physiologically involved in the expansion of memory and/or effector cells and thus in the persistence of memory. IL-6 did not alter the duration of Ag-presenting activity. Both CFSE dilution studies and labeling with BrdU indicated that IL-6 does not effect proliferative rates of responding CD4 T cells. By contrast, annexin V staining was diminished in responding cells from the IL-6-treated animals, particularly among those cells that had undergone five or more divisions. These results indicate that IL-6 reduces the level of apoptosis among Ag-stimulated cells; thus, it plays a central role in determining numbers of memory and/or effector CD4 T cells in response to immunization over extended periods.
B Cell Hyperresponsiveness and Expansion of Mature Follicular B Cells but Not of Marginal Zone B Cells in NFATc2/c3 Double-Deficient Mice
Authors: Samanta Devapriya Nandini , Palmetshofer Alois , Marinkovic Dragan , Wirth Thomas , Serfling Edgar , Nitschke Lars
Published: April 2014

Marginal zone (MZ) B cells and peritoneal B-1 cells provide a first defense system of thymus-independent Ab responses against foreign pathogens and therefore share a number of functional properties. Recently, development of B-1a cells was shown to be controlled by the transcription factor NFATc1. We show here that mice deficient for NFATc2 and c3 display a distinct lower representation of MZ B cells, which is correlated with a reduced capturing of trinitrophenyl-Ficoll. In contrast, mature follicular B cells from NFATc2/c3−/− mice are strongly increased in number. NFATc2/c3−/− B cells exhibit a marked increase in BCR-induced intracellular Ca2+ mobilization and proliferation. However, trinitrophenyl-Ficoll-specific IgM and IgG3 responses of NFATc2/c3-deficient mice are intact, and chimeric mice reconstituted with NFATc2/3-deficient B cells show a normal number of MZ B cells and normal BCR responses. These observations suggest that the strongly elevated Th2 cytokine milieu in NFATc2/c3-deficient mice leads to a hyperactivation of mature, follicular B cells, whereas MZ B cells are less responsive to these signals.
Exocytosis of CTLA-4 Is Dependent on Phospholipase D and ADP Ribosylation Factor-1 and Stimulated during Activation of Regulatory T Cells
Authors: Mead Karen I. , Zheng Yong , Manzotti Claire N. , Perry Laura C. A. , Liu Michael K. P. , Burke Fiona , Powner Dale J. , Wakelam Michael J. O. , Sansom David M.
Published: April 2014

CTLA-4 is an essential protein in the regulation of T cell responses that interacts with two ligands found on the surface of APCs (CD80 and CD86). CTLA-4 is itself poorly expressed on the T cell surface and is predominantly localized to intracellular compartments. We have studied the mechanisms involved in the delivery of CTLA-4 to the cell surface using a model Chinese hamster ovary cell system and compared this with activated and regulatory human T cells. We have shown that expression of CTLA-4 at the plasma membrane (PM) is controlled by exocytosis of CTLA-4-containing vesicles and followed by rapid endocytosis. Using selective inhibitors and dominant negative mutants, we have shown that exocytosis of CTLA-4 is dependent on the activity of the GTPase ADP ribosylation factor-1 and on phospholipase D activity. CTLA-4 was identified in a perinuclear compartment overlapping with the cis-Golgi marker GM-130 but did not colocalize strongly with lysosomal markers such as CD63 and lysosome-associated membrane protein. In regulatory T cells, activation of phospholipase D was sufficient to trigger release of CTLA-4 to the PM but did not inhibit endocytosis. Taken together, these data suggest that CTLA-4 may be stored in a specialized compartment in regulatory T cells that can be triggered rapidly for deployment to the PM in a phospholipase D- and ADP ribosylation factor-1-dependent manner.
Intraepithelial Cell Neutralization of HIV-1 Replication by IgA
Authors: Huang Yung T. , Wright Alison , Gao Xing , Kulick Lesya , Yan Huimin , Lamm Michael E.
Published: April 2014

HIV is transmitted sexually through mucosal surfaces where IgA Abs are the first line of immune defense. In this study, we used paired IgA and IgG mAbs against HIV gp160 to study intraepithelial cell neutralization and inhibition of HIV replication. African green monkey kidney cells, Vero C1008, polarizable epithelial cells transfected to express the polymeric Ig receptor (pIgR), were transfected with HIV proviral DNA, and intracellular neutralization mediated by the mAbs was assessed. D47A and D19A IgA, which neutralized HIV in a conventional assay, potently inhibited intracellular HIV replication as assessed by infecting HeLa-CD4-long terminal repeat/β-galactosidase cells (human cervical carcinoma cell line) and CEMx174 cells (human T cell line) with apical supernatant, basolateral medium, and cell lysate from transfected cells. D47A also inhibited the production of virus as assessed by direct assay of p24. In contrast, D47 and D19 IgG, sharing the same V regions, but which were not transcytosed by the pIgR, did not inhibit intracellular HIV replication, nor did D47A and D19A IgA in pIgR− cells, incapable of transcytosing IgA. Confocal immunofluorescence microscopy showed prominent colocalization of HIV protein and D47A, in agreement with the intracellular neutralization data. D10A, which did not neutralize HIV in the conventional assay, and irrelevant IgA did not show intracellular neutralization or colocalization. Control studies with two kinds of conditioned medium confirmed that HIV neutralization had indeed occurred inside the cells. Thus, during its transcytosis through epithelial cells, HIV-specific IgA can neutralize HIV replication.
Polymorphonuclear Neutrophils Improve Replication ofChlamydia pneumoniaeIn Vivo upon MyD88-Dependent Attraction
Authors: Rodriguez Nuria , Fend Falko , Jennen Luise , Schiemann Matthias , Wantia Nina , da Costa Clarissa U. Prazeres , Dürr Susanne , Heinzmann Ulrich , Wagner Hermann , Miethke Thomas
Published: April 2014

Chlamydia pneumoniae, an obligate intracellular bacterium, causes pneumonia in humans and mice. In this study, we show that GR1+/CD45+ polymorphonuclear neutrophils (PMN) surprisingly increase the bacterial load of C. pneumoniae in vivo. Upon intranasal infection of wild-type mice, the lung weight is increased; the cytokines TNF, IL-12p40, and IFN-γ, as well as the chemokines keratinocyte-derived chemokine, MCP-1, and MIP-2 are secreted; and GR1+/CD45+ PMN are recruited into lungs 3 days postinfection. In contrast, in infected MyD88-deficient mice, which lack a key adaptor molecule in the signaling cascade of TLRs and IL-1R family members, the increase of the lung weight is attenuated, and from the analyzed cyto- and chemokines, only IL-12p40 is detectable. Upon infection, almost no influx of inflammatory cells into lungs of MyD88-deficient mice can be observed. Six days postinfection, however, MyD88-deficient mice were able to produce TNF, IFN-γ, keratinocyte-derived chemokine, and MCP-1 in amounts similar to wild-type mice, but failed to secrete IL-12p40 and MIP-2. At this time point, the infection increased the lung weight to a level similar to wild-type mice. Curiously, the chlamydial burden in MyD88-deficient mice 3 days postinfection is lower than in wild-type mice, a finding that can be reproduced in wild-type mice by depletion of GR1+ cells. In analyzing how PMN influence the chlamydial burden in vivo, we find that PMN are infected and enhance the replication of C. pneumoniae in epithelial cells. Thus, the lower chlamydial burden in MyD88-deficient mice can be explained by the failure to recruit PMN.
Transmembrane TNF Is Sufficient to Initiate Cell Migration and Granuloma Formation and Provide Acute, but Not Long-Term, Control ofMycobacterium tuberculosisInfection
Authors: Saunders Bernadette M. , Tran Stephen , Ruuls Sigrid , Sedgwick Jonathon D. , Briscoe Helen , Britton Warwick J.
Published: April 2014

TNF is critical for immunity against Mycobacterium tuberculosis infection; however, the relative contributions of the soluble and transmembrane forms of TNF in this immunity are unknown. Using memTNF mice, which express only the transmembrane form of TNF, we have addressed this question. Wild-type (WT), TNF−/−, and transmembrane TNF (memTNF) mice were infected with M. tuberculosis by aerosol. TNF−/− mice developed overwhelming infection with extensive pulmonary necrosis and died after only 33 days. memTNF mice, like WT mice, contained bacterial growth for over 16 wk, developed an Ag-specific T cell response, and initially displayed compact granulomas, comprised of both lymphocytes and macrophages. Expression of mRNA for the chemokines CXCL10, CCL3, CCL5, and CCL7 was comparable in both WT and memTNF mice. As the infection progressed, however, the pulmonary lesions in memTNF mice became larger and more diffuse, with increased neutrophil accumulation and necrosis. This was accompanied by increased influx of activated memory T cells into the lungs of memTNF mice. Eventually, these mice succumbed to infection with a mean time to death of 170 days. The expression of memTNF on T cells is functionally important because the transfer of T cells from memTNF, but not TNF−/− mice, into either RAG−/− or TNF−/− mice conferred the same survival advantage on the M. tuberculosis-infected recipient mice, as the transfer of WT T cells. Therefore, memTNF, in the absence of soluble TNF, is sufficient to control acute, but not chronic, M. tuberculosis infection, in part through its expression on T cells.
Molecular Basis for the Potency of IL-10-Deficient Dendritic Cells as a Highly Efficient APC System for Activating Th1 Response
Authors: He Qing , Moore Terri T. , Eko Francis O. , Lyn Deborah , Ananaba Godwin A. , Martin Amy , Singh Shailesh , James Lillard , Stiles Jonathan , Black Carolyn M. , Igietseme Joseph U.
Published: April 2014

Identification and targeting of novel immunobiological factors that regulate the induction of Th1 cells are crucial for designing effective vaccines against certain intracellular pathogens, including Chlamydia. IL-10-deficient dendritic cells (DC) are potent APCs and effective cellular vaccines that activate a high frequency of specific Th1 cells. To elucidate the molecular basis for the potency of the IL-10-deficient APC system, we tested the hypothesis that Chlamydia Ag-primed IL-10 knockout (IL-10KO) DC are quantitatively and qualitatively distinct in their metabolic characteristics relating to T cell activation. Using a combination of RT-PCR, two-dimensional gel electrophoresis, and MALDI-TOF-based proteomics analyses, the transcriptional and translational activities of Chlamydia-pulsed DC from wild-type and IL-10KO mice were assessed. IL-10 deficiency caused early maturation and activation of pulsed DC (i.e., high CD11c, CD40, CD80, CD83, CD86, IL-1, IL-12, and the T cell-attracting chemokine CCL27/CTACK) and consequently an enhanced ability to process and present Ags for a rapid and robust T cell activation. Supporting comparative proteomics revealed further that IL-10 deficient DC possess specific immunobiological properties, e.g., the T cell-attracting chemokine CCL27/CTACK, calcium-dependent protein kinase, and the IL-1/IL-12 inducer, NKR-P1A (CD161), which differentiated them immunologically from wild-type DC that express molecules relating to anti-inflammatory, differentiative, and metabolic processes, e.g., the anti-IL-12 molecule peroxisome proliferator-activated receptor-α and thymidine kinase. Collectively, these results provide a molecular basis for the high Th1-activating capacity of IL-10KO APC and may provide unique immunomodulation targets when designing vaccines against pathogens controlled by T cell immunity.
Differential Regulation of β-Defensin Expression in Human Skin by Microbial Stimuli
Authors: Sørensen Ole E. , Thapa Dharma R. , Rosenthal Adam , Liu Lide , Roberts Alice A. , Ganz Tomas
Published: April 2014

In response to infection, epithelia mount an innate immune response that includes the production of antimicrobial peptides. However, the pathways that connect infection and inflammation with the induction of antimicrobial peptides in epithelia are not understood. We analyzed the molecular links between infection and the expression of three antimicrobial peptides of the β-defensin family, human β-defensin (hBD)-1, hBD-2, and hBD-3 in the human epidermis. After exposure to microbe-derived molecules, both monocytes and lymphocytes stimulated the epidermal expression of hBD-1, hBD-2, and hBD-3. The induced expression of hBD-3 was mediated by transactivation of the epidermal growth factor receptor. The mechanisms of induction of hBD-1 and hBD-3 were distinct from each other and from the IL-1-dependent induction of hBD-2 expression. Thus during inflammation, epidermal expression of β-defensins is mediated by at least three different mechanisms.
STAT1 Signaling Regulates Tumor-Associated Macrophage-Mediated T Cell Deletion
Authors: Kusmartsev Sergei , Gabrilovich Dmitry I.
Published: April 2014

It is well established that tumor progression is associated with the accumulation of myeloid suppressive cells, which in mice include Gr-1+ immature myeloid cells and F4/80+ macrophages. The paradox is that with the exception of terminal stages of the disease or chemotherapy treatment, tumor-bearing mice or cancer patients do not display a profound systemic immune suppression. We therefore raised the question as to whether myeloid cell-mediated T cell suppression is controlled at a local level at the site of the tumor. We have demonstrated that after adoptive transfer to tumor-bearing recipients, Gr-1+ (immature myeloid cells) freshly isolated from spleens of tumor-bearing mice become F4/80+ tumor-associated macrophages (TAM). These TAM, but not F4/80+ macrophages or Gr-1+ cells freshly isolated from spleens of tumor-bearing or naive mice were able to inhibit T cell-mediated immune response in vitro via induction of T cell apoptosis. Arginase and NO were both responsible for the apoptotic mechanism, and were seen only in TAM, but not in freshly isolated Gr1+ cells. Using the analysis of STAT activity in combination with STAT knockout mice, we have determined that STAT1, but not STAT3 or STAT6, was responsible for TAM-suppressive activity.