bluuebunny/crossref_metadata_2025 huggingface dataset:
Cutting Edge: Trans-Signaling via the Soluble IL-6R Abrogates the Induction of FoxP3 in Naive CD4+CD25− T Cells
Authors: Dominitzki Sabine , Fantini Massimo C. , Neufert Clemens , Nikolaev Alexei , Galle Peter R. , Scheller Jürgen , Monteleone Giovanni , Rose-John Stefan , Neurath Markus F. , Becker Christoph
Published: April 2014

Chronic inflammatory diseases may develop when regulatory T cells (Tregs) fail to control the balance between tolerance and immunity. Alternatively, activated immune cells might prevent the induction or activation of Tregs in such diseases. In this study, we demonstrate that trans-signaling into T cells via the soluble IL-6 receptor completely abrogates the de novo induction of adaptive Tregs. Mechanistically, IL-6 trans-signaling augmented the expression of the TGF-β signaling inhibitor SMAD7. Consequently, SMAD7 overexpression in T cells using newly created transgenic mice rendered CD4+CD25− T cells resistant to the induction of FoxP3. Finally, IL-6 trans-signaling inhibited Treg-mediated suppression in a murine model of colitis. In summary, IL-6 trans-signaling into T cells emerges as a key pathway for blockade of the development of adaptive Tregs and thus may play a pivotal role in shifting the balance between effector and regulatory T cell numbers in chronic inflammatory and autoimmune diseases.
Cutting Edge: A Hypomorphic Mutation in Igβ (CD79b) in a Patient with Immunodeficiency and a Leaky Defect in B Cell Development
Authors: Dobbs A. Kerry , Yang Tianyu , Farmer Dana , Kager Leo , Parolini Ornella , Conley Mary Ellen
Published: April 2014

Although null mutations in Igα have been identified in patients with defects in B cell development, no mutations in Igβ have been reported. We recently identified a patient with a homozygous amino acid substitution in Igβ, a glycine to serine at codon 137, adjacent to the cysteine required for the disulfide bond between Igα and Igβ. This patient has a small percentage of surface IgMdim B cells in the peripheral circulation (0.08% compared with 5–20% in healthy controls). Using expression vectors in 293T cells or Jurkat T cells, we show that the mutant Igβ can form disulfide-linked complexes and bring the μ H chain to the cell surface as part of the BCR but is inefficient at both tasks. The results show that minor changes in the ability of the Igα/Igβ complex to bring the BCR to the cell surface have profound effects on B cell development.
The Adaptor Molecule CIN85 Regulates Syk Tyrosine Kinase Level by Activating the Ubiquitin-Proteasome Degradation Pathway
Authors: Peruzzi Giovanna , Molfetta Rosa , Gasparrini Francesca , Vian Laura , Morrone Stefania , Piccoli Mario , Frati Luigi , Santoni Angela , Paolini Rossella
Published: April 2014

Triggering of mast cells and basophils by IgE and Ag initiates a cascade of biochemical events that lead to cell degranulation and the release of allergic mediators. Receptor aggregation also induces a series of biochemical events capable of limiting FcεRI-triggered signals and functional responses. Relevant to this, we have recently demonstrated that Cbl-interacting 85-kDa protein (CIN85), a multiadaptor protein mainly involved in the process of endocytosis and vesicle trafficking, regulates the Ag-dependent endocytosis of the IgE receptor, with consequent impairment of FcεRI-mediated cell degranulation. The purpose of this study was to further investigate whether CIN85 could alter the FcεRI-mediated signaling by affecting the activity and/or expression of molecules directly implicated in signal propagation. We found that CIN85 overexpression inhibits the FcεRI-induced tyrosine phosphorylation of phospholipase Cγ, thus altering calcium mobilization. This functional defect is associated with a substantial decrease of Syk protein levels, which are restored by the use of selective proteasome inhibitors, and it is mainly due to the action of the ubiquitin ligase c-Cbl. Furthermore, coimmunoprecipitation experiments demonstrate that CIN85 overexpression limits the ability of Cbl to bind suppressor of TCR signaling 1 (Sts1), a negative regulator of Cbl functions, while CIN85 knockdown favors the formation of Cbl/Sts1 complexes. Altogether, our findings support a new role for CIN85 in regulating Syk protein levels in RBL-2H3 cells through the activation of the ubiquitin-proteasome pathway and provide a mechanism for this regulation involving c-Cbl ligase activity.
Enhancement of Human Melanoma Antigen Expression by IFN-β
Authors: Dunn Ian S. , Haggerty Timothy J. , Kono Michihiro , Durda Paul J. , Butera David , Macdonald David B. , Benson Elizabeth M. , Rose Lenora B. , Kurnick James T.
Published: April 2014

Although many immunotherapeutic investigations have focused on improving the effector limb of the antitumor response, few studies have addressed preventing the loss of tumor-associated Ag (TAA) expression, associated with immune escape by tumors. We found that TAA loss from human melanomas usually results from reversible gene down-regulation, rather than gene deletion or mutation. Previously, we showed that inhibitors of MAPK-signaling pathways up-regulate TAA expression in melanoma cell lines. We have now identified IFN-β as an additional stimulus to TAA expression, including Melan-A/MART-1, gp100, and MAGE-A1. IFN-β (but neither IFN-α nor IFN-γ) augmented both protein and mRNA expression of melanocytic TAA in 15 melanoma lines (irrespective of initial Ag-expression levels). Treatment of low Ag melanoma lines with IFN-β increased expression of melanocyte-lineage Ags, inducing susceptibility to lysis by specific CTLs. Treatment with IFN-β also enhances expression of class I HLA molecules, thereby inducing both nominal TAA and the presenting HLA molecule. Data from fluorescent cellular reporter systems demonstrated that IFN-β triggers promoter activation, resulting in augmentation of Ag expression. In addition to enhancing TAA expression in melanomas, IFN-β also stimulated expression of the melanocytic Ag gp100 in cells of other neural crest-derived tumor lines (gliomas) and certain unrelated tumors. Because IFN-β is already approved for human clinical use in other contexts, it may prove useful as a cotreatment for augmenting tumor Ag expression during immunotherapy.
Chronic Immunodeficiency in Mice Lacking RasGRP1 Results in CD4 T Cell Immune Activation and Exhaustion
Authors: Priatel John J. , Chen Xiaoxi , Zenewicz Lauren A. , Shen Hao , Harder Kenneth W. , Horwitz Marc S. , Teh Hung-Sia
Published: April 2014

The Ras-guanyl nucleotide exchange factor RasGRP1 is an important link between TCR-mediated signaling and the activation of Ras and its downstream effectors. RasGRP1 is especially critical for the survival and differentiation of developing thymocytes whereas negative selection of thymocytes bearing an autoreactive TCR appears to be RasGRP1 independent. Despite apparently normal central tolerance, RasGRP1−/− mice spontaneously acquire an acutely activated and proliferating CD4 T cell population that exhibits characteristics of T cell exhaustion, including strong expression of programmed cell death-1. To elucidate the basis for RasGRP1−/− CD4 T cell immune activation, we initiated a series of adoptive transfer experiments. Remarkably, the copious amounts of cytokines and self-Ags present in hosts made lymphopenic through irradiation failed to induce the majority of RasGRP1−/− CD4 T cells to enter cell cycle. However, their infusion into either congenitally T cell- or T/B cell-deficient recipients resulted in robust proliferation and L-selectin down-regulation. These findings imply that the activation and proliferation of RasGRP1−/− CD4 T cells may be dependent on their residence in a chronically immunocompromised environment. Accordingly, bacterial and viral challenge experiments revealed that RasGRP1−/− mice possess a weakened immune system, exhibiting a T cell-autonomous defect in generating pathogen-specific T cells and delayed pathogen clearance. Collectively, our study suggests that chronic T cell immunodeficiency in RasGRP1−/− mice may be responsible for CD4 T cell activation, proliferation, and exhaustion.
Age-Dependent TCR Revision Mediated by Interaction between αβ TCR and Self-Antigens
Authors: Takase Mitsuyo , Kanagawa Edith M. , Kanagawa Osami
Published: April 2014

Interactions between TCR and self-peptide/MHC complex play an important role in homeostasis and Ag reactivity of mature peripheral T cells. In this report, we demonstrate that the interactions between mature peripheral T cells and endogenous Ags have a negative impact on the maintenance of foreign Ag-specific T cells in an age-dependent manner. This is mediated by RAG-dependent secondary rearrangement of the TCR α-chain (receptor revision). The TCR revision in mature T cells is readily observed in mouse expressing transgenic TCR α-chain inserted into the physiological locus (knockin mouse) but not in conventional transgenic mouse with an identical TCR α-chain. Thus, our results suggest that under physiological conditions in which all TCR α-chains are susceptible to deletion by secondary rearrangement, TCR revision in mature peripheral T cells is an ongoing process in adult animals and contributes to age-dependent changes in T cell function and repertoire.
OX40 Costimulation Promotes Persistence of Cytomegalovirus-Specific CD8 T Cells: A CD4-Dependent Mechanism
Authors: Humphreys Ian R. , Loewendorf Andrea , de Trez Carl , Schneider Kirsten , Benedict Chris A. , Munks Michael W. , Ware Carl F. , Croft Michael
Published: April 2014

The mechanisms that regulate CMV-specific T cell responses in vivo are poorly understood. During murine CMV infection of B6 mice, primary responses in the spleen are dominated by CD8 T cells reactive with antigenic epitopes in M45, M57, and m139 murine CMV gene products. However, during the later persistent phase of infection, CD8 T cell responses to epitopes in m139 and M38 viral gene products predominate. The basis for this shift in CD8 T populations is unknown. In this study, we demonstrate that OX40, a TNFR superfamily member, specifically regulates the accumulation of CD8 T cells reactive with the persistent-phase epitopes. Defective CD8 T cell responses in OX40−/− mice were replicated in MHC class II−/− mice implying that CD4 T cells in part controlled the differentiation of the CD8 T cell clones responsive to these epitopes during persistent infection. Furthermore, treatment of infected mice with an agonist OX40 Ab induced expansion of protective primary virus-specific CD8 T cells independent of CD4 T cell help, but CD4 T cells were crucial for anti-OX40 to promote CD8 T cells reactive to the persistent dominant epitopes. Collectively, these results indicate manipulation of OX40 may be useful in improving cellular immunotherapy regimes for treatment of persistent virus infections.
NKT Cell-Derived Urokinase-Type Plasminogen Activator Promotes Peripheral Tolerance Associated with Eye
Authors: Sonoda Koh-Hei , Nakamura Takahiko , Young Howard A. , Hart David , Carmeliet Peter , Stein-Streilein Joan
Published: April 2014

In a model of peripheral tolerance called anterior chamber-associated immune deviation (ACAID), the differentiation of the T regulatory cells depends on NKT cells and occurs in the spleen. In this study, we show that NKT cells that express the invariant (i) TCR and are the CD1d-reactive NKT cells (required for development of peripheral tolerance) actually produced urokinase-type plasminogen activator (uPA) during tolerance induction. The RT-PCR and in vitro plasmin assay showed that splenic iNKT cells derived uPA-converted plasminogen to plasmin. Moreover, uPA was required for tolerance induction because uPA knockout (KO) mice did not develop peripheral tolerance or develop CD8+ T regulatory cells after Ag inoculation into the anterior chamber. In contrast, other aspects of ACAID-induced tolerance, including recruitment of iNKT cells to the spleen and production of IL-10 by iNKT cells, were unchanged in uPA-deficient mice. The adoptive transfer of splenic NKT cells from wild-type mice restored ACAID in Jα18 KO mice (iNKT cell deficient), but NKT cells from uPA KO mice did not. We postulate that the mechanism of action of uPA is through its binding to the uPAR receptor, and enzymatic cleavage of plasminogen to plasmin, which in turn activates latent TGFβ. In conclusion, uPA derived from iNKT cells is required to induce peripheral tolerance via the eye.
TCR Affinity Promotes CD8+ T Cell Expansion by Regulating Survival
Authors: Hommel Mirja , Hodgkin Philip D.
Published: April 2014

Ligation with high affinity ligands are known to induce T lymphocytes to become fully activated effector cells while ligation with low affinity ligands (or partial agonists) may result in a delayed or incomplete response. We have examined the quantitative features of CD8+ T cell proliferation induced by peptides of different TCR affinities at a range of concentrations in the mouse OT-I model. Both the frequency of cells responding and the average time taken for cells to reach their first division are affected by peptide concentration and affinity. Consecutive division times, however, remained largely unaffected by these variables. Importantly, we identified affinity to be the sole regulator of cell death in subsequent division. These results suggest a mechanism whereby TCR affinity detection can modulate the subsequent rate of T cell growth and ensure the dominance of higher affinity clones over time.
Despite Increased CD4+Foxp3+ Cells within the Infection Site, BALB/c IL-4 Receptor-Deficient Mice Reveal CD4+Foxp3-Negative T Cells as a Source of IL-10 inLeishmania majorSusceptibility
Authors: Nagase Hisashi , Jones Kathryn M. , Anderson Charles F. , Noben-Trauth Nancy
Published: April 2014

BALB/c IL-4Rα−/− mice, despite the absence of IL-4/IL-13 signaling and potent Th2 responses, remain highly susceptible to Leishmania major substain LV39 due exclusively to residual levels of IL-10. To address the contribution of CD4+CD25+ T regulatory (Treg) cells to IL-10-mediated susceptibility, we depleted CD4+CD25+ cells in vivo and reconstituted IL-4Rα × RAG2 recipients with purified CD4+CD25− T cells. Although anti-CD25 mAb treatment significantly decreased parasite numbers in IL-4Rα−/− mice, treatment with anti-IL-10R mAb virtually eliminated L. major parasites in both footpad and dermal infection sites. In addition, IL-4Rα × RAG2 mice reconstituted with CD4+ cells depleted of CD25+ Treg cells remained highly susceptible to infection. Analysis of L. major-infected BALB/c and IL-4Rα−/− inflammatory sites revealed that the majority of IL-10 was secreted by the CD4+Foxp3− population, with a fraction of IL-10 coming from CD4+Foxp3+ Treg cells. All T cell IFN-γ production was also derived from the CD4+Foxp3− population. Nevertheless, the IL-4Rα−/−-infected ear dermis, but not draining lymph nodes, consistently displayed 1.5- to 2-fold greater percentages of CD4+CD25+ and CD4+Foxp3+ Treg cells compared with the BALB/c-infected dermis. Thus, CD4+Foxp3− T cells are a major source of IL-10 that disrupts IFN-γ activity in L. major-susceptible BALB/c mice. However, the increase in CD4+Foxp3+ T cells within the IL-4Rα−/− dermis implies a possible IL-10-independent role for Treg cells within the infection site, and may indicate a novel immune escape mechanism used by L. major parasites in the absence of IL-4/IL-13 signaling.
Mycobacterium tuberculosisInfects Dendritic Cells with High Frequency and Impairs Their Function In Vivo
Authors: Wolf Andrea J. , Linas Beth , Trevejo-Nuñez Giraldina J. , Kincaid Eleanor , Tamura Toshiki , Takatsu Kiyoshi , Ernst Joel D.
Published: April 2014

Mycobacterium tuberculosis (Mtb) is thought to reside in macrophages, although infected dendritic cells (DCs) have been observed. Thus, although cellular associations have been made, global characterization of the cells harboring Mtb is lacking. We have performed temporal and quantitative characterization of the cells harboring Mtb following aerosol infection of mice by using GFP-expressing bacteria and flow cytometry. We discovered that Mtb infects phagocytic cells of diverse phenotypes, that the predominant infected cell populations change with time, and that myeloid DCs are the major cell population infected with Mtb in the lungs and lymph nodes. We also found that the bacteria in the lung-draining lymph node are transported there from the lungs by a CCL19/21-dependent mechanism and that the transport of bacteria to the lymph node is a transient phenomenon despite chronic infection. In addition, we found that the lymph node cell subsets that are most efficacious in stimulating Mtb-specific, TCR-transgenic CD4+ T lymphocytes are not infected with the bacteria and are scarce or absent from the lungs of infected mice. Finally, we found that the lung cell populations that are infected with Mtb at high frequency are relatively ineffective at stimulating Ag-specific CD4+ T lymphocytes, and we have obtained evidence that live Mtb can inhibit MHC class II Ag presentation without a decrease in the surface expression of MHC class II. These results indicate that Mtb targets DC migration and Ag presentation in vivo to promote persistent infection.
Baseline Viral Load and Immune Activation Determine the Extent of Reconstitution of Innate Immune Effectors in HIV-1-Infected Subjects Undergoing Antiretroviral Treatment
Authors: Chehimi Jihed , Azzoni Livio , Farabaugh Matthew , Creer Shenoa A. , Tomescu Costin , Hancock Aidan , Mackiewicz Agnes , D’Alessandro Lara , Ghanekar Smita , Foulkes Andrea S. , Mounzer Karam , Kostman Jay , Montaner Luis J.
Published: April 2014

We analyzed dendritic cell (DC) and NK cell compartments in relation to CD4 recovery in 21 HIV-infected subjects followed to <50 copies/ml once starting antiretroviral therapy (ART) and observed for 52 wk of sustained suppression. Although CD4 counts increased in all subjects in response to ART, we observed a restoration of functional plasmacytoid DC (PDC) after 52 wk of sustained suppression under ART (from 1850 cells/ml to 4550 cells/ml) to levels comparable to controls (5120 cells/ml) only in subjects with a low baseline viral load, which also rapidly suppressed to <50 copies/ml upon ≤60 days from ART initiation. Recovery of PDC at week 52 correlates with level of CD95 expression on CD8 T cells and PDC frequency following first ART suppression. NK cytotoxic activity increased rapidly upon viral suppression (VS) and correlated with PDC function at week 52. However, restoration of total NK cells was incomplete even after 52 wk on ART (73 cells/μl vs 122 cells/μl in controls). Direct reconstitution experiments indicate that NK cytotoxic activity against virally infected target cells requires DC/NK cooperation, and can be recovered upon sustained VS and recovery of functional PDC (but not myeloid DC) from ART-suppressed subjects. Our data indicate that viremic HIV-infected subjects may have different levels of reconstitution of DC and NK-mediated function following ART, with subjects with lower initial viremia and the greatest reduction of baseline immune activation at VS achieving the greatest level of innate effector cell reconstitution.
African Trypanosomiasis: Naturally Occurring Regulatory T Cells Favor Trypanotolerance by Limiting Pathology Associated with Sustained Type 1 Inflammation
Authors: Guilliams Martin , Oldenhove Guillaume , Noel Wim , Hérin Michel , Brys Lea , Loi Patrizia , Flamand Véronique , Moser Muriel , De Baetselier Patrick , Beschin Alain
Published: April 2014

Tolerance to African trypanosomes requires the production of IFN-γ in the early stage of infection that triggers the development of classically activated macrophages controlling parasite growth. However, once the first peak of parasitemia has been controlled, down-regulation of the type 1 immune response has been described. In this study, we have evaluated whether regulatory T cells (Tregs) contribute to the limitation of the immune response occurring during Trypanosoma congolense infection and hereby influence the outcome of the disease in trypanotolerant C57BL/6 host. Our data show that Foxp3+ Tregs originating from the naturally occurring Treg pool expanded in the spleen and the liver of infected mice. These cells produced IL-10 and limited the production of IFN-γ by CD4+ and CD8+ effector T cells. Tregs also down-regulated classical activation of macrophages resulting in reduced TNF-α production. The Treg-mediated suppression of the type 1 inflammatory immune response did not hamper parasite clearance, but was beneficial for the host survival by limiting the tissue damages, including liver injury. Collectively, these data suggest a cardinal role for naturally occurring Tregs in the development of a trypanotolerant phenotype during African trypanosomiasis.
Regulation of Antibody-Dependent Cellular Cytotoxicity by IgG Intrinsic and Apparent Affinity for Target Antigen
Authors: Tang Yong , Lou Jianlong , Alpaugh R. Katherine , Robinson Matthew K. , Marks James D. , Weiner Louis M.
Published: April 2014

Unconjugated mAbs have emerged as useful cancer therapeutics. Ab-dependent cellular cytotoxicity (ADCC) is believed to be a major antitumor mechanism of some anticancer Abs. However, the factors that regulate the magnitude of ADCC are incompletely understood. In this study, we described the relationship between Ab affinity and ADCC. A series of human IgG1 isotype Abs was created from the anti-HER2/neu (also named c-erbB2) C6.5 single-chain Fv (scFv) and its affinity mutants. The scFv affinities range from 10−7 to 10−11 M, and the IgG Abs retain the affinities of the scFv from which they were derived. The apparent affinity of the Abs ranged from nearly 10−10 M (the lowest affinity variant) to almost 10−11 M (the other variants). The IgG molecules were tested for their ability to elicit ADCC in vitro against three tumor cell lines with differing levels of HER2/neu expression using unactivated human PBMC from healthy donors as the effector cells. The results demonstrated that both the apparent affinity and intrinsic affinity of the Abs studied regulate ADCC. High-affinity tumor Ag binding by the IgGs led to the most efficient and powerful ADCC. Tumor cells expressing high levels of HER2/neu are more susceptible to the ADCC triggered by Abs than the cells expressing lower amounts of HER2/neu. These findings justify the examination of high affinity Abs for ADCC promotion. Because high affinity may impair in vivo tumor targeting, a careful examination of Ab structure to function relationships is required to develop optimized therapeutic unconjugated Abs.
IgE-Antibody-Dependent Immunotherapy of Solid Tumors: Cytotoxic and Phagocytic Mechanisms of Eradication of Ovarian Cancer Cells
Authors: Karagiannis Sophia N. , Bracher Marguerite G. , Hunt James , McCloskey Natalie , Beavil Rebecca L. , Beavil Andrew J. , Fear David J. , Thompson Richard G. , East Nicholas , Burke Frances , Moore Robert J. , Dombrowicz David D. , Balkwill Frances R. , Gould Hannah J.
Published: April 2014

Abs have a paramount place in the treatment of certain, mainly lymphoid, malignancies, although tumors of nonhemopoietic origin have proved more refractory ones. We have previously shown that the efficacy of immunotherapy of solid tumors, in particular ovarian carcinoma, may be improved by the use of IgE Abs in place of the conventional IgG. An IgE Ab (MOv18 IgE) against an ovarian-tumor-specific Ag (folate binding protein), in combination with human PBMC, introduced into ovarian cancer xenograft-bearing mice, greatly exceeded the analogous IgG1 in promoting survival. In this study, we analyzed the mechanisms by which MOv18 IgE may exert its antitumor activities. Monocytes were essential IgE receptor-expressing effector cells that mediated the enhanced survival of tumor-bearing mice by MOv18 IgE and human PBMC. Monocytes mediated MOv18 IgE-dependent ovarian tumor cell killing in vitro by two distinct pathways, cytotoxicity and phagocytosis, acting respectively through the IgE receptors FcεRI and CD23. We also show that human eosinophils were potent effector cells in MOv18 IgE Ab-dependent ovarian tumor cell cytotoxicity in vitro. These results demonstrate that IgE Abs can engage cell surface IgE receptors and activate effector cells against ovarian tumor cells. Our findings offer a framework for an improved immunotherapeutic strategy for combating solid tumors.
Altered Immune Function during Long-Term Host-Tumor Interactions Can Be Modulated to Retard Autochthonous Neoplastic Growth
Authors: Stewart Trina J. , Abrams Scott I.
Published: April 2014

Ag-specific and generalized forms of immunosuppression have been documented in animal tumor models. However, much of our knowledge on tumor-induced immunosuppression was acquired using tumor implant models, which do not reiterate the protracted nature of host-tumor interactions. Therefore, a transgenic mouse model of autochthonous mammary tumor development and progression was chosen to investigate the long-term consequences of neoplastic growth on the immune system. In vitro proliferation of unfractionated splenocytes from tumor-bearing mice, as assessed by [3H]thymidine uptake, was inhibited by the presence of suppressor cells within these splenocyte preparations, because purifying the T cells restored their biological activity. However, the level of inhibition did not correlate with either tumor load or the percentage of myeloid-derived CD11b+Gr1+ cells. To evaluate tumor-specific immune dysfunction, transgenic mice were challenged with autologous tumor cells. Mice with extensive, but not minimal autochthonous tumor burdens demonstrated a significantly enhanced rate of autologous tumor growth compared with age-matched controls. In contrast, an allogeneic tumor challenge was efficiently rejected from both groups of transgenic mice. It was also noted that allogeneic tumor challenge of mice with minimal disease significantly inhibited autochthonous primary tumor growth. We therefore demonstrated that 1) a generalized form of immunosuppression occurred, but not as a result of permanent alterations to T cell function, because purified T cell subsets retained normal biological activity following polyclonal or allostimulation; and 2) tumor-specific immunosuppression emerged as a consequence of tumor progression, but could be modulated to enhance antitumor responses against autochthonous primary neoplastic growth.
Targeting Molecular and Cellular Inhibitory Mechanisms for Improvement of Antitumor Memory Responses Reactivated by Tumor Cell Vaccine
Authors: Webster W. Scott , Thompson R. Houston , Harris Kimberley J. , Frigola Xavier , Kuntz Susan , Inman Brant A. , Dong Haidong
Published: April 2014

Development of effective vaccination approaches to treat established tumors represents a focus of intensive research because such approaches offer the promise of enhancing immune system priming against tumor Ags via restimulation of pre-existing (memory) antitumoral helper and effector immune cells. However, inhibitory mechanisms, which function to limit the recall responses of tumor-specific immunity, remain poorly understood and interfere with therapies anticipated to induce protective immunity. The mouse renal cell carcinoma (RENCA) tumor model was used to investigate variables affecting vaccination outcomes. We demonstrate that although a whole cell irradiated tumor cell vaccine can trigger a functional antitumor memory response in the bone marrows of mice with established tumors, these responses do not culminate in the regression of established tumors. In addition, a CD103+ regulatory T (Treg) cell subset accumulates within the draining lymph nodes of tumor-bearing mice. We also show that B7-H1 (CD274, PD-L1), a negative costimulatory ligand, and CD4+ Treg cells collaborate to impair the recall responses of tumor-specific memory T cells. Specifically, mice bearing large established RENCA tumors were treated with tumor cell vaccination in combination with B7-H1 blockade and CD4+ T cell depletion (triple therapy treatment) and monitored for tumor growth and survival. Triple treatment therapy induced complete regression of large established RENCA tumors and raised long-lasting protective immunity. These results have implications for developing clinical antitumoral vaccination regimens in the setting in which tumors express elevated levels of B7-H1 in the presence of abundant Treg cells.
T Cells Express α7-Nicotinic Acetylcholine Receptor Subunits That Require a Functional TCR and Leukocyte-Specific Protein Tyrosine Kinase for Nicotine-Induced Ca2+ Response
Authors: Razani-Boroujerdi Seddigheh , Boyd R. Thomas , Dávila-García Martha I. , Nandi Jayashree S. , Mishra Neerad C. , Singh Shashi P. , Pena-Philippides Juan Carlos , Langley Raymond , Sopori Mohan L.
Published: April 2014

Acute and chronic effects of nicotine on the immune system are usually opposite; acute treatment stimulates while chronic nicotine suppresses immune and inflammatory responses. Nicotine acutely raises intracellular calcium ([Ca2+]i) in T cells, but the mechanism of this response is unclear. Nicotinic acetylcholine receptors (nAChRs) are present on neuronal and non-neuronal cells, but while in neurons, nAChRs are cation channels that participate in neurotransmission; their structure and function in nonexcitable cells are not well-defined. In this communication, we present evidence that T cells express α7-nAChRs that are critical in increasing [Ca2+]i in response to nicotine. Cloning and sequencing of the receptor from human T cells showed a full-length transcript essentially identical to the neuronal α7-nAChR subunit (>99.6% homology). These receptors are up-regulated and tyrosine phosphorylated by treatment with nicotine, anti-TCR Abs, or Con A. Furthermore, knockdown of the α7-nAChR subunit mRNA by RNA interference reduced the nicotine-induced Ca2+ response, but unlike the neuronal receptor, α-bungarotoxin and methyllycaconitine not only failed to block, but also actually raised [Ca2+]i in T cells. The nicotine-induced release of Ca2+ from intracellular stores in T cells did not require extracellular Ca2+, but, similar to the TCR-mediated Ca2+ response, required activation of protein tyrosine kinases, a functional TCR/CD3 complex, and leukocyte-specific tyrosine kinase. Moreover, CD3ζ and α7-nAChR coimmunoprecipitated with anti-CD3ζ or anti-α7-nAChR Abs. These results suggest that in T cells, α7-nAChR, despite its close sequence homology with neuronal α7-nAChR, fails to form a ligand-gated Ca2+ channel, and that the nicotine-induced rise in [Ca2+]i in T cells requires functional TCR/CD3 and leukocyte-specific tyrosine kinase.
Viral Replication Capacity as a Correlate of HLA B57/B5801-Associated Nonprogressive HIV-1 Infection
Authors: Navis Marjon , Schellens Ingrid , van Baarle Debbie , Borghans José , van Swieten Peter , Miedema Frank , Kootstra Neeltje , Schuitemaker Hanneke
Published: April 2014

HLA B57 and the closely related HLA B5801 are over-represented among HIV-1 infected long-term nonprogressors (LTNPs). It has been suggested that this association between HLA B57/5801 and asymptomatic survival is a consequence of strong CTL responses against epitopes in the viral Gag protein. Moreover, CTL escape mutations in Gag would coincide with viral attenuation, resulting in low viral load despite evasion from immune control. In this study we compared HLA B57/5801 HIV-1 infected progressors and LTNPs for sequence variation in four dominant epitopes in Gag and their ability to generate CTL responses against these epitopes and the autologous escape variants. Prevalence and appearance of escape mutations in Gag epitopes and potential compensatory mutations were similar in HLA B57/5801 LTNPs and progressors. Both groups were also indistinguishable in the magnitude of CD8+ IFN-γ responses directed against the wild-type or autologous escape mutant Gag epitopes in IFN-γ ELISPOT analysis. Interestingly, HIV-1 variants from HLA B57/5801 LTNPs had much lower replication capacity than the viruses from HLA B57/5801 progressors, which did not correlate with specific mutations in Gag. In conclusion, the different clinical course of HLA B57/5801 LTNPs and progressors was not associated with differences in CTL escape mutations or CTL activity against epitopes in Gag but rather with differences in HIV-1 replication capacity.
Neisseria meningitidis PorB, a TLR2 Ligand, Induces an Antigen-Specific Eosinophil Recall Response: Potential Adjuvant for Helminth Vaccines?
Authors: Burke Jennifer M. , Ganley-Leal Lisa M. , Khatri Asma , Wetzler Lee M.
Published: April 2014

Efficacious adjuvants are important components of new vaccines. The neisserial outer membrane protein, PorB, is a TLR2 ligand with unique adjuvant activity. We demonstrate that PorB promotes Th2-skewed cellular immune response to the model Ag, OVA, in mice, including Ag-specific recall eosinophil recruitment to the peritoneum. PorB induces chemokine secretion by myeloid cells using both TLR2-dependent and -independent mechanisms, suggesting that anatomical distribution of TLR2+ cells may not be a limiting factor for potential vaccine strategies. The results from this study suggest that PorB, and other TLR2 ligands, may be ideal for use against pathogens where eosinophilia may be protective, such as parasitic helminths.
Dendritic Cell Type Determines the Mechanism of Bystander Suppression by Adaptive T Regulatory Cells Specific for the Minor Antigen HA-1
Authors: Derks Richard A. , Jankowska-Gan Ewa , Xu Qingyong , Burlingham William J.
Published: April 2014

One hallmark of acquired tolerance is bystander suppression, a process whereby Ag-specific (adaptive) T regulatory cells (TR) inhibit the T effector cell response both to specific Ag and to a colocalized third-party Ag. Using peripheral blood T cells from recipients of HLA-identical kidney transplants as responders in the trans vivo-delayed type hypersensitivity assay, we found that dendritic cells (DC), but not monocyte APCs, could mediate bystander suppression of EBV-specific recall response. When HA-1H peptide was added to mixtures of plasmacytoid DC (pDC) and T cells, bystander suppression of the response to a colocalized recall Ag occurred primarily via indolamine-2,3-dioxygenase (IDO) production. Similarly, addition of HA-1H peptide to cocultures of T cells and pDC, but not myeloid DC (mDC), induced IDO activity in vitro. When mDC presented HA-1H peptide to Ag-specific CD8+ TR, cytokine release (TGF-β, IL-10, or both) was the primary mode of bystander suppression. Bystander suppression via mDC was reversed not only by Ab to TGF-β and its receptor on T cells, but also by Ab to thrombospondin-1. EBV addition did not induce IDO or thrombospondin-1 in T-DC cocultures, suggesting that these DC products are not induced by T effector cells, but only by TR cells. These results shed light upon the mechanism of bystander suppression by donor Ag-specific TR in patients with organ transplant tolerance and underscores the distinct and critical roles of mDC and pDCs in this phenomenon.
Invariant NKT Cells Biased for IL-5 Production Act as Crucial Regulators of Inflammation
Authors: Sakuishi Kaori , Oki Shinji , Araki Manabu , Porcelli Steven A. , Miyake Sachiko , Yamamura Takashi
Published: April 2014

Although invariant NKT (iNKT) cells play a regulatory role in the pathogenesis of autoimmune diseases and allergy, an initial trigger for their regulatory responses remains elusive. In this study, we report that a proportion of human CD4+ iNKT cell clones produce enormous amounts of IL-5 and IL-13 when cocultured with CD1d+ APC in the presence of IL-2. Such IL-5 bias was never observed when we stimulated the same clones with α-galactosylceramide or anti-CD3 Ab. Suboptimal TCR stimulation by plate-bound anti-CD3 Ab was found to mimic the effect of CD1d+ APC, indicating the role of TCR signaling for selective induction of IL-5. Interestingly, DNA microarray analysis identified IL-5 and IL-13 as the most highly up-regulated genes, whereas other cytokines produced by iNKT cells, such as IL-4 and IL-10, were not significantly induced. Moreover, iNKT cells from BALB/c mice showed similar IL-5 responses after stimulation with IL-2 ex vivo or in vivo. The iNKT cell subset producing IL-5 and IL-13 could play a major role in the development of allergic disease or asthma and also in the immune regulation of Th1 inflammation.
A Y Chromosome-Linked Factor Impairs NK T Development
Authors: Wesley Johnna D. , Tessmer Marlowe S. , Paget Christophe , Trottein François , Brossay Laurent
Published: April 2014

Vα14 invariant (Vα14i) NK T cell development is unique from mainstream T cell selection, and the polygenic factors that influence NK T cell ontogeny are still unclear. In this study, we report the absence of Vα14i NK T cells in B6.IFN-αβR1−/− male mice, whereas both the conventional T and NK cell populations are relatively unaffected. The lack of Vα14i NK T cells in the B6.IFN-αβR1−/− males is not due to an insufficient level of CD1d1 or a defect in CD1d1-Ag presentation, but it is intrinsic to the male Vα14i NK T cells. This surprising defect displays ≥99% penetrance in the male population, whereas female mice remain unaffected, indicating the deficiency is not X linked. Analysis of the Vα14i NK T cell compartment in B6.Tyk2−/−, B6.STAT1−/−, 129.IFN-αβR1−/−, and B6.IFN-αβR1−/+ mice demonstrate that the deficiency is linked to the Y chromosome, but independent of IFN-αβ. This is the first study demonstrating that Y-linked genes can exclusively impact Vα14i NK T development and further highlight the unique ontogeny of these innate T cells.
Characterization of Early Stages of Human B Cell Development by Gene Expression Profiling
Authors: Hystad Marit E. , Myklebust June H. , Bø Trond H. , Sivertsen Einar A. , Rian Edith , Forfang Lise , Munthe Else , Rosenwald Andreas , Chiorazzi Michael , Jonassen Inge , Staudt Louis M. , Smeland Erlend B.
Published: April 2014

We have characterized several stages of normal human B cell development in adult bone marrow by gene expression profiling of hemopoietic stem cells, early B (E-B), pro-B, pre-B, and immature B cells, using RNA amplification and Lymphochip cDNA microarrays (n = 6). Hierarchical clustering of 758 differentially expressed genes clearly separated the five populations. We used gene sets to investigate the functional assignment of the differentially expressed genes. Genes involved in VDJ recombination as well as B lineage-associated transcription factors (TCF3 (E2A), EBF, BCL11A, and PAX5) were turned on in E-B cells, before acquisition of CD19. Several transcription factors with unknown roles in B lymphoid cells demonstrated interesting expression patterns, including ZCCHC7 and ZHX2. Compared with hemopoietic stem cells and pro-B cells, E-B cells had increased expression of 18 genes, and these included IGJ, IL1RAP, BCL2, and CD62L. In addition, E-B cells expressed T/NK lineage and myeloid-associated genes including CD2, NOTCH1, CD99, PECAM1, TNFSF13B, and MPO. Expression of key genes was confirmed at the protein level by FACS analysis. Several of these Ags were heterogeneously expressed, providing a basis for further subdivision of E-B cells. Altogether, these results provide new information regarding expression of genes in early stages of human B cell development.
Vitamin A Metabolites Induce Gut-Homing FoxP3+ Regulatory T Cells
Authors: Kang Seung G. , Lim Hyung W. , Andrisani Ourania M. , Broxmeyer Hal E. , Kim Chang H.
Published: April 2014

In this study, we report a novel biological function of vitamin A metabolites in conversion of naive FoxP3− CD4+ T cells into a unique FoxP3+ regulatory T cell subset (termed “retinoid-induced FoxP3+ T cells”) in both human and mouse T cells. We found that the major vitamin A metabolite all-trans-retinoic acid induces histone acetylation at the FoxP3 gene promoter and expression of the FoxP3 protein in CD4+ T cells. The induction of retinoid-induced FoxP3+ T cells is mediated by the nuclear retinoic acid receptor α and involves T cell activation driven by mucosal dendritic cells and costimulation through CD28. Retinoic acid can promote TGF-β1-dependent generation of FoxP3+ regulatory T cells but decrease the TGF-β1- and IL-6-dependent generation of inflammatory Th17 cells in mouse T cells. Retinoid-induced FoxP3+ T cells can efficiently suppress target cells and, thus, have a regulatory function typical for FoxP3+ T cells. A unique cellular feature of these regulatory T cells is their high expression of gut-homing receptors that are important for migration to the mucosal tissues particularly the small intestine. Taken together, these results identify retinoids as positive regulatory factors for generation of gut-homing FoxP3+ T cells.
The Endothelial Cell-Produced Antiangiogenic Cytokine Vascular Endothelial Growth Inhibitor Induces Dendritic Cell Maturation
Authors: Tian Fang , Grimaldo Sammy , Fugita Mitsugu , Cutts Jonita , Vujanovic Nikola L. , Li Lu-Yuan
Published: April 2014

Angiogenesis is an essential component of chronic inflammation that is linked to carcinogenesis. In this study, we report that human vascular endothelial growth inhibitor (VEGI, TNF superfamily 15), an endothelial cell-produced antiangiogenic cytokine, induces mouse dendritic cell (DC) maturation, a critical event in inflammation-initiated immunity. VEGI-stimulated bone marrow-derived immature DCs display early activation of maturation signaling molecules NF-κB, STAT3, p38, and JNK, and cytoskeleton reorganization and dendrite formation. The activation signals are partially inhibited by using a neutralizing Ab against death domain-containing receptor-3 (DR3) or a truncated form of DR3 consisting of the extracellular domain, indicating an involvement of DR3 in the transmission of VEGI activity. A VEGI isoform, TL1A, does not induce similar activities under otherwise identical experimental conditions. Additionally, the cells reveal significantly enhanced expression of mature DC-specific marker CD83, secondary lymphoid tissue-directing chemokine receptor CCR7, the MHC class-II protein (MHC-II), and costimulatory molecules CD40, CD80, and CD86. Functionally, the cells exhibit decreased Ag endocytosis, increased cell surface distribution of MHC-II, and increased secretion of IL-12 and TNF. Moreover, VEGI-stimulated DCs are able to facilitate the differentiation of CD4+ naive T cells in cocultures. These findings suggest that the anticancer activity of VEGI arises from coupling the inhibition of endothelial cell growth with the promotion of the adaptive immune mechanisms through the stimulation of DC maturation.
DAP10 Deficiency Breaks the Immune Tolerance against Transplantable Syngeneic Melanoma
Authors: Hyka-Nouspikel Nevila , Lucian Linda , Murphy Erin , McClanahan Terri , Phillips Joseph H.
Published: April 2014

DAP10, an activating adaptor protein, associates with the NKG2D protein to form a multisubunit receptor complex that is expressed in lymphoid and myeloid cells. The ligands for NKG2D-DAP10 receptor are expressed in both normal and tumor cells, suggesting distinct roles for this receptor in autoimmunity and cancer. In this study, we report that constitutive DAP10 activating signaling is part of regulatory mechanisms that control immunity against tumors. Mice lacking DAP10 (DAP10KO), showed enhanced immunity against melanoma malignancies due to hyperactive functioning of NK1.1+CD3+ NKT cells. DAP10 deficiency resulted in substantially increased NKT cell functions, including cytokine production and cytotoxicity, leading to efficient killing of melanoma tumors. Moreover, the antitumor phenotype of DAP10KO mice correlated with impaired activation status of CD4+CD25+ T regulatory cells (Tregs). Upon activation, DAP10KO Tregs maintained higher levels of IL-2 and produced significantly lower amounts of IL-10 and IFN-γ cytokines when compared with wild-type Tregs. Our data suggest that DAP10 signaling is involved in adjusting the activation threshold and generation of NKT cells and Tregs to avoid autoreactivity, but also modulates antitumor mechanisms.
Attenuation of Experimental Autoimmune Myositis by Blocking ICOS-ICOS Ligand Interaction
Authors: Katsumata Yasuhiro , Harigai Masayoshi , Sugiura Tomoko , Kawamoto Manabu , Kawaguchi Yasushi , Matsumoto Yoh , Kohyama Kuniko , Soejima Makoto , Kamatani Naoyuki , Hara Masako
Published: April 2014

Polymyositis (PM) is an acquired, systemic, connective tissue disease characterized by the proximal muscle weakness and infiltration of mononuclear cells into the affected muscles. To understand its etiology and immunopathogenesis, appropriate animal model is required. It has been demonstrated that immunization with native human skeletal C protein induces severe and reproducible experimental autoimmune myositis (EAM) in Lewis rats, and that the muscle inflammatory lesions in the EAM mimic those of human PM. In the present study, we prepared recombinant skeletal C protein fragment and succeeded in inducing as severe EAM as that by native C protein. We found ICOS expression on muscle fiber-infiltrating T cells in the EAM rats, but not in normal rats. Treatment with anti-ICOS mAb reduced incidence and severity of myositis; decreased the number of muscle-infiltrating CD11b/c+, TCR+, and CD8a+ cells; and inhibited the expression of IL-1α and CCL2 in the hamstring muscles of the EAM rats. However, the treatment neither inhibited serum anti-C protein IgG level, C protein-induced proliferation of lymph node (LN) cells, or LN T cells, nor production of IFN-γ by C protein-stimulated LN cells in EAM rats. These data indicate that analysis of C protein-induced EAM provides not only insights into pathogenesis of PM, but also useful information regarding development of effective immunotherapy against the disease. ICOS-ICOS ligand interaction would be a novel therapeutic target for PM.
The Role of B Cells in the Development of CD4 Effector T Cells during a Polarized Th2 Immune Response
Authors: Liu Qian , Liu Zhugong , Rozo Cristina T. , Hamed Hossein A. , Alem Farhang , Urban Joseph F. , Gause William C.
Published: April 2014

Previous studies have suggested that B cells promote Th2 cell development by inhibiting Th1 cell differentiation. To examine whether B cells are directly required for the development of IL-4-producing T cells in the lymph node during a highly polarized Th2 response, B cell-deficient and wild-type mice were inoculated with the nematode parasite, Nippostrongylus brasiliensis. On day 7, in the absence of increased IFN-γ, IL-4 protein and gene expression from CD4 T cells in the draining lymph nodes were markedly reduced in B cell-deficient mice and could not be restored by multiple immunizations. Using a DO11.10 T cell adoptive transfer system, OVA-specific T cell IL-4 production and cell cycle progression, but not cell surface expression of early activation markers, were impaired in B cell-deficient recipient mice following immunization with N. brasiliensis plus OVA. Laser capture microdissection and immunofluorescent staining showed that pronounced IL-4 mRNA and protein secretion by donor DO11.10 T cells first occurred in the T cell:B cell zone of the lymph node shortly after inoculation of IL-4−/− recipients, suggesting that this microenvironment is critical for initial Th2 cell development. Reconstitution of B cell-deficient mice with wild-type naive B cells, or IL-4−/− B cells, substantially restored Ag-specific T cell IL-4 production. However, reconstitution with B7-1/B7-2-deficient B cells failed to rescue the IL-4-producing DO11.10 T cells. These results suggest that B cells, expressing B7 costimulatory molecules, are required in the absence of an underlying IFN-γ-mediated response for the development of a polarized primary Ag-specific Th2 response in vivo.