bluuebunny/crossref_metadata_2025 huggingface dataset:
Hydrodynamic-Based Delivery of an Interleukin-22-Ig Fusion Gene Ameliorates Experimental Autoimmune Myocarditis in Rats
Authors: Chang He , Hanawa Haruo , Liu Hui , Yoshida Tsuyoshi , Hayashi Manabu , Watanabe Ritsuo , Abe Satoru , Toba Ken , Yoshida Kaori , Elnaggar Raafat , Minagawa Shiro , Okura Yuji , Kato Kiminori , Kodama Makoto , Maruyama Hiroki , Miyazaki Junichi , Aizawa Yoshifusa
Published: April 2014

IL-22 is one of several cytokines with limited homology to IL-10. However, the biological activities of IL-22 are mostly unknown. The purpose of this study was to evaluate the effect of IL-22 on rat experimental autoimmune myocarditis (EAM) and elucidate an aspect of the biological activities of IL-22. Rats were immunized on day 0; IL-22-Ig-treated rats were injected with pCAGGS-IL-22-Ig and control rats with pCAGGS-Ig using hydrodynamics-based gene delivery on day 1 or day 6. IL-22-Ig gene therapy administered on day 1 or day 6 after immunization was effective in controlling EAM as monitored by the heart weight to body weight ratio, and the myocarditis area in rats was sacrificed on day 17. Examination of the expression of IL-22-related genes in purified cells from EAM hearts suggested that IL-22-Ig acting target cells were noncardiomyocytic (NC) noninflammatory cells such as fibroblasts, smooth muscle cells, and endothelial cells. Therefore, we examined the effect of rIL-22 or serum containing IL-22-Ig on the expression of immune-relevant genes in IL-1-stimulated NC cells cultured from EAM hearts. Results showed that the expression of immunologic molecules (PGE synthase, cyclooxygenase-2, MIP-2, MCP-1, IL-6, and cytokine-induced neutrophil chemoattractant-2) in IL-1-stimulated NC cells was significantly decreased by rIL-22 or serum containing IL-22-Ig. EAM was suppressed by hydrodynamics-based delivery of plasmid DNA encoding IL-22-Ig, and the reason for this effectiveness may be that IL-22 suppressed gene expression of PG synthases, IL-6, and chemokines in activated NC noninflammatory cells.
Invariant NKT Cells Rapidly Activated via Immunization with Diverse Contact Antigens Collaborate In Vitro with B-1 Cells to Initiate Contact Sensitivity
Authors: Campos Regis A. , Szczepanik Marian , Lisbonne Mariette , Itakura Atsuko , Leite-de-Moraes Maria , Askenase Philip W.
Published: April 2014

In cutaneous contact sensitivity there is an early elicited innate cascade of complement, mast cells, and platelets activated via IgM Abs. This response is required to initiate the elicitation of acquired classical contact sensitivity by leading to local recruitment of effector T cells. We recently performed in vivo experiments showing that collaboration is required between innate-like invariant Vα14+ NKT cells (iNKT) and the innate-like B-1 B cell subset to induce this initiation process. Contact sensitization triggers iNKT cells to produce IL-4 to coactivate the B-1 cells along with specific Ag for production of the initiating IgM Abs. We now describe in vitro collaboration of iNKT and B-1 cells. Normal peritoneal B-1 cells, incubated in vitro with soluble Ag, and with 1-h in vivo immune iNKT cells producing IL-4, are activated to mediate the contact sensitivity-initiation cascade. The three components of this process can be activated by different Ag. Thus, 1-h iNKT cell activation, B-1 cell stimulation, and generation of immune effector T cells can be induced by sensitization with three different Ag to respectively generate IL-4 and Ag-specific IgM Abs, to recruit the Ag-specific effector T cells. These findings have relevance to allergic and autoimmune diseases in which infections can trigger exacerbation of T cell responses to allergens or to autoantigens.
Peroxisome Proliferator-Activated Receptor γ Promotes Lymphocyte Survival through Its Actions on Cellular Metabolic Activities
Authors: Jo Seung-Hee , Yang Chunyan , Miao Qi , Marzec Michal , Wasik Mariusz A. , Lu Pin , Wang Y. Lynn
Published: April 2014

Peroxisome proliferator-activated receptor γ (PPARγ) is a metabolic regulator that plays an important role in sensitizing tissues to the action of insulin and in normalizing serum glucose and free fatty acids in type 2 diabetic patients. The receptor has also been implicated in the modulation of inflammatory responses, and ligands of PPARγ have been found to induce apoptosis in lymphocytes. However, apoptosis induction may not depend on the receptor, because high doses of PPARγ agonists are required for this process. Using cells containing or lacking PPARγ, we reported previously that PPARγ attenuates apoptosis induced by cytokine withdrawal in a murine lymphocytic cell line via a receptor-dependent mechanism. PPARγ exerts this effect by enhancing the ability of cells to maintain their mitochondrial membrane potential during cytokine deprivation. In this report, we demonstrate that activation of PPARγ also protects cells from serum starvation-induced apoptosis in human T lymphoma cell lines. Furthermore, we show that the survival effect of PPARγ is mediated through its actions on cellular metabolic activities. In cytokine-deprived cells, PPARγ attenuates the decline in ATP level and suppresses accumulation of reactive oxygen species (ROS). Moreover, PPARγ regulates ROS through its coordinated transcriptional control of proteins and enzymes involved in ROS scavenging, including uncoupling protein 2, catalase, and copper zinc superoxide dismutase. Our studies identify cell survival promotion as a novel activity of PPARγ and suggest that PPARγ may modulate cytokine withdrawal-induced activated T cell death.
Immature Dendritic Cells Suppress Collagen-Induced Arthritis by In Vivo Expansion of CD49b+ Regulatory T Cells
Authors: Charbonnier Louis-Marie , van Duivenvoorde Leonie M. , Apparailly Florence , Cantos Céline , Han Wanda G. H. , Noël Danièle , Duperray Christophe , Huizinga Tom W. J. , Toes René E. M. , Jorgensen Christian , Louis-Plence Pascale
Published: April 2014

Dendritic cells (DCs) are specialized APCs with an important role in the initiation and regulation of immune responses. Immature DCs (iDCs) reportedly mediate tolerance in the absence of maturation/inflammatory stimuli, presumably by the induction of regulatory T cells. In this study, we show for the first time that repetitive iDC injections trigger the expansion of a novel regulatory population with high immunomodulatory properties, able to protect mice from collagen-induced arthritis. These regulatory T cells are characterized by the expression of the CD49b molecule and correspond to a CD4+ α-galactosylceramide/CD1d-nonrestricted T cell population producing IL-10. Adoptive transfer of <105 TCRβ+CD49b+ cells isolated from the liver of iDCs-vaccinated mice, conferred a complete protection against arthritis. This protection was associated with an attenuation of the B and T cell response associated with a local secretion of IL-10. Thus, together these data demonstrate that iDCs can expand and activate a novel regulatory population of CD49b+ T cells, with high immunosuppressive potential able to mediate protection against a systemic autoimmune disease.
Impaired Memory CD8 T Cell Development in the Absence of Methyl-CpG-Binding Domain Protein 2
Authors: Kersh Ellen N.
Published: April 2014

Intracellular differentiation events that determine which cells develop into memory CD8 T cells are currently incompletely understood. Methyl-CpG-binding domain protein 2 (MBD2) is a transcriptional repressor that binds to methylated DNA and mediates the biological consequences of epigenetic gene methylation. The role of MBD2 during the differentiation of naive CD8 T cells into effector and memory cells was determined following acute infection of MBD2-deficient mice with lymphocytic choriomeningitis virus. Despite rapid viral clearance and an efficient primary effector CD8 T cell response, reduced numbers of Ag-specific memory CD8 T cells were observed. Importantly, the appearance of precursor memory cells (IL-7Rαhigh) was delayed. The remaining MBD2−/− memory cells were not fully protective during rechallenge, and memory cell characteristics were altered with regard to surface markers (IL-7Rα, KLRG-1, CD27, and others) and cytokine production. The defect was CD8 T cell intrinsic, because memory cell development was also delayed when MBD2−/− CD8 T cells were adoptively transferred into SCID mice. These data demonstrate that MBD2 is a previously unrecognized intracellular factor required for the efficient generation of protective memory CD8 T cells.
Constitutive Expression of Murine Decay-Accelerating Factor 1 Is Controlled by the Transcription Factor Sp1
Authors: Cauvi David M. , Cauvi Gabrielle , Pollard K. Michael
Published: April 2014

The complement regulatory protein decay-accelerating factor (DAF or CD55) protects host tissue from complement-mediated injury by inhibiting the classical and alternative complement pathways. Besides its role in complement regulation, DAF has also been shown to be a key player in T cell immunity. Modulation of DAF expression could therefore represent a critical regulatory mechanism in both innate and adaptive immune responses. To identify and characterize key transcriptional regulatory elements controlling mouse Daf1 expression, a 2.5-kb fragment corresponding to the 5′ flanking region of the mouse Daf1 gene was cloned. Sequence analysis showed that the mouse Daf1 promoter lacks conventional TATA and CCAAT boxes and displays a high guanine and cytosine content. RACE was used to identify one major and two minor transcription start sites 47, 20, and 17 bp upstream of the translational codon. Positive and negative regulatory regions were identified by transiently transfecting sequential 5′deletion constructs of the 5′flanking region into NIH/3T3, M12.4, and RAW264.7 cells. Mutational analyses of the promoter region combined with Sp1-specific ELISA showed that the transcription factor Sp1 is required for basal transcription and LPS-induced expression of the Daf1 gene. These findings provide new information on the regulation of the mouse Daf1 promoter and will facilitate further studies on the expression of Daf1 during immune responses.
Mapping the Binding Site on CD8β for MHC Class I Reveals Mutants with Enhanced Binding
Authors: Devine Lesley , Thakral Deepshi , Nag Shanta , Dobbins Jessica , Hodsdon Michael E. , Kavathas Paula B.
Published: April 2014

In an effective immune response, CD8+ T cell recognition of virally derived Ag, bound to MHC class I, results in killing of infected cells. The CD8αβ heterodimer acts as a coreceptor with the TCR, to enhance sensitivity of the T cells to peptide/MHC class I, and is two orders of magnitude more efficient as a coreceptor than the CD8αα. To understand the important interaction between CD8αβ and MHC class I, we created a panel of CD8β mutants and identified mutations in the CDR1, CDR2, and CDR3 loops that decreased binding to MHC class I tetramers as well as mutations that enhanced binding. We tested the coreceptor function of a subset of reducing and enhancing mutants using a T cell hybridoma and found similar reducing and enhancing effects. CD8β-enhancing mutants could be useful for immunotherapy by transduction into T cells to enhance T cell responses against weak Ags such as those expressed by tumors. We also addressed the question of the orientation of CD8αβ with MHC class I using CD8α mutants expressed as a heterodimer with wild-type CD8α or CD8β. The partial rescuing of binding with wild-type CD8β compared with wild-type CD8α is consistent with models in which either the topology of CD8αα and CD8αβ binding to MHC class I is different or CD8αβ is capable of binding in both the T cell membrane proximal and distal positions.
Aspergillus fumigatus Induces Innate Immune Responses in Alveolar Macrophages through the MAPK Pathway Independently of TLR2 and TLR4
Authors: Dubourdeau Marc , Athman Rafika , Balloy Viviane , Huerre Michel , Chignard Michel , Philpott Dana J. , Latgé Jean-Paul , Ibrahim-Granet Oumaïma
Published: April 2014

Aspergillus fumigatus causes invasive aspergillosis in immunosuppressed patients. In the immunocompetent host, inhaled conidia are cleared by alveolar macrophages. The signaling pathways of the alveolar macrophage involved in the clearance of A. fumigatus are poorly understood. Therefore, we investigated the role of TLRs in the immune response against A. fumigatus and their contribution to the signaling events triggered in murine alveolar macrophages upon infection with A. fumigatus conidia. Specifically, we examined the MAPKs and NF-κB activation and cytokine signaling. Our investigations revealed that immunocompetent TLR2, TLR4, and MyD88 knockout mice were not more susceptible to invasive aspergillosis as compared with wild-type mice and that the in vitro phosphorylation of the MAPKs ERK and p38 was not affected in TLR2, TLR4, or MyD88 knockout mice following stimulation with conidia. In vivo experiments suggest that ERK was an essential MAPK in the defense against A. fumigatus, whereas the activation of NF-κB appeared to play only a secondary role. In conclusion, our findings demonstrate that TLR2/4 recognition and MyD88 signaling are dispensable for the clearance of A. fumigatus under immunocompetent situations. Furthermore, our data stress the important role of ERK activation in innate immunity to A. fumigatus.
Listeriolysin O-Deficient Listeria monocytogenes as a Vaccine Delivery Vehicle: Antigen-Specific CD8 T Cell Priming and Protective Immunity
Authors: Hamilton Sara E. , Badovinac Vladimir P. , Khanolkar Aaruni , Harty John T.
Published: April 2014

Strains of Listeria monocytogenes (LM) that are deficient in the virulence factor listeriolysin O (LLO) are highly attenuated and are thought not to elicit protective immunity. This failure has been attributed to the inability of the bacterium to enter the host cell cytosol and access MHC class I Ag processing machinery. We reexamined this issue using recombinant strains of LM that are deficient in LLO but express an additional CD8 T cell epitope derived from lymphocytic choriomeningitis virus. After infection with LLO-deficient strains, we find sizable priming of epitope-specific CD8 T cells and the development of a functional memory cell population. Mice primed with the LLO-deficient LM strain are equally resistant against high-dose challenge with virulent LM as mice primed with wild-type virulent bacteria and also resist heterologous challenge with lymphocytic choriomeningitis virus. Interestingly, priming with a low dose of LLO-deficient LM, which occurred in environment of reduced inflammation (IFN-γ), allowed rapid amplification of Ag-specific CD8 T cells by booster immunization, despite an undetectable primary response. We conclude that the generation of protective immunity by LLO-deficient strains of LM does in fact occur and that this highly attenuated LM strain may be a useful platform for vaccine delivery.
First Identification of a Chemotactic Receptor in an Invertebrate Species: Structural and Functional Characterization of Ciona intestinalis C3a Receptor
Authors: Melillo Daniela , Sfyroera Georgia , De Santis Rosaria , Graziano Rita , Marino Rita , Lambris John D. , Pinto Maria Rosaria
Published: April 2014

In mammals, the bioactive fragment C3a, released from C3 during complement activation, is a potent mediator of inflammatory reactions and exerts its functional activity through the specific binding to cell surface G protein-coupled seven-transmembrane receptors. Recently, we demonstrated a Ciona intestinalis C3a (CiC3a)-mediated chemotaxis of hemocytes in the deuterostome invertebrate Ciona intestinalis and suggested an important role for this molecule in inflammatory processes. In the present work, we have cloned and characterized the receptor molecule involved in the CiC3a-mediated chemotaxis and studied its expression profile. The sequence, encoding a 95,394 Da seven-transmembrane domain protein, shows the highest sequence homology with mammalian C3aRs. Northern blot analysis revealed that the CiC3aR is expressed abundantly in the heart and neural complex and to a lesser extent in the ovaries, hemocytes, and larvae. Three polyclonal Abs raised in rabbits against peptides corresponding to CiC3aR regions of the first and second extracellular loop and of the third intracellular loop react specifically in Western blotting with a single band of 98–102 kDa in hemocyte protein extracts. Immunostaining performed on circulating hemocytes with the three specific Abs revealed that CiC3aR is constitutively expressed only in hyaline and granular amoebocytes. In chemotaxis experiments, the Abs against the first and second extracellular loop inhibited directional migration of hemocytes toward the synthetic peptide reproducing the CiC3a C-terminal sequence, thus providing the compelling evidence that C. intestinalis expresses a functional C3aR homologous to the mammalian receptor. These findings further elucidate the evolutionary origin of the vertebrate complement-mediated proinflammatory process.
DNA Immunization against Tissue-Restricted Antigens Enhances Tumor Immunity after Allogeneic Hemopoietic Stem Cell Transplantation
Authors: Perales Miguel-Angel , Diab Adi , Cohen Adam D. , Huggins Deonka W. , Guevara-Patiño José A. , Hubbard Vanessa M. , Engelhorn Manuel E. , Kochman Adam A. , Eng Jeffrey M. , Mortazavi Fariborz , Alpdogan Onder , Terwey Theis H. , Heller Glenn , Wolchok Jedd D. , Houghton Alan N. , van den Brink Marcel R. M.
Published: April 2014

Malignant relapse remains a major problem for recipients of allogeneic hemopoietic stem cell transplantation (HSCT). We hypothesized that immunization of allogeneic HSCT recipients against tissue-restricted Ags using DNA vaccines would decrease the risk of relapse without enhancing graft-vs-host disease (GVHD). Using the mouse B16 melanoma model, we found that post-HSCT DNA immunization against a single tumor Ag induces tumor rejection that is significantly greater than HSCT alone in a T cell-depleted MHC-matched minor Ag-mismatched allogeneic HSCT model (LP → B6). In treatment models, post-HSCT DNA immunization provides significantly greater overall survival than the vaccine alone. Donor leukocyte infusion further enhances tumor-free survival, including in treatment models. There was no GVHD in HSCT recipients treated with DNA vaccination and donor leukocyte infusion. Further analysis demonstrated that these effects are dependent on CD8+ T cells of donor origin that recognize multiple epitopes. These results demonstrate that DNA immunization against tissue-restricted Ags after allogeneic T cell-depleted HSCT can induce potent antitumor effects without causing GVHD.
Antibody Targeting to a Class I MHC-Peptide Epitope Promotes Tumor Cell Death
Authors: Wittman Vaughan P. , Woodburn David , Nguyen Tiffany , Neethling Francisca A. , Wright Stephen , Weidanz Jon A.
Published: April 2014

Therapeutic mAbs that target tumor-associated Ags on the surface of malignant cells have proven to be an effective and specific option for the treatment of certain cancers. However, many of these protein markers of carcinogenesis are not expressed on the cells’ surface. Instead these tumor-associated Ags are processed into peptides that are presented at the cell surface, in the context of MHC class I molecules, where they become targets for T cells. To tap this vast source of tumor Ags, we generated a murine IgG2a mAb, 3.2G1, endowed with TCR-like binding specificity for peptide-HLA-A*0201 (HLA-A2) complex and designated this class of Ab as TCR mimics (TCRm). The 3.2G1 TCRm recognizes the GVL peptide (GVLPALPQV) from human chorionic gonadotropin β presented by the peptide-HLA-A*0201 complex. When used in immunofluorescent staining reactions using GVL peptide-loaded T2 cells, the 3.2G1 TCRm specifically stained the cells in a peptide and Ab concentration-dependent manner. Staining intensity correlated with the extent of cell lysis by complement-dependent cytotoxicity (CDC), and a peptide concentration-dependent threshold level existed for the CDC reaction. Staining of human tumor lines demonstrated that 3.2G1 TCRm was able to recognize endogenously processed peptide and that the breast cancer cell line MDA-MB-231 highly expressed the target epitope. The 3.2G1 TCRm-mediated CDC and Ab-dependent cellular cytotoxicity of a human breast carcinoma line in vitro and inhibited in vivo tumor implantation and growth in nude mice. These results provide validation for the development of novel TCRm therapeutic reagents that specifically target and kill tumors via recognition and binding to MHC-peptide epitopes.
The Inflammatory Caspases: Key Players in the Host Response to Pathogenic Invasion and Sepsis
Authors: Nadiri Amal , Wolinski Melissa K. , Saleh Maya
Published: April 2014

Caspases are cysteinyl-aspartate-specific proteinases known for their role in apoptosis (cell death or apoptotic caspases) and proinflammatory cytokine maturation (inflammatory caspases). The inflammatory caspases were among the first to be discovered, but only recently have the mechanisms leading to their activation and inhibition begun to be elucidated. In this review, we examine the biochemistry, substrates, and function of this unique family of inflammatory proteases, highlight the most recent findings regarding their regulatory mechanisms, and discuss what remains to be understood about their roles in health and disease.
Cutting Edge: T Cell Requirement for CD28 Costimulation Is Due to Negative Regulation of TCR Signals by PTEN
Authors: Buckler Jodi L. , Walsh Patrick T. , Porrett Paige M. , Choi Yongwon , Turka Laurence A.
Published: April 2014

Recent studies suggest that the phosphatase and tensin homolog deleted on chromosome 10 (PTEN) plays a critical role in the maintenance of self-tolerance. Using T cell-specific PTEN knockout mice (PTENΔT), we have identified a novel mechanism by which PTEN regulates T cell tolerance. We found that TCR stimulation alone, without CD28 costimulation, is sufficient to induce hyperactivation of the PI3K pathway, which leads to enhanced IL-2 production by naive PTENΔT T cells. Importantly, as a result of this increased response to TCR stimulation, PTENΔT CD4+ T cells no longer require CD28 costimulation for in vitro or in vivo expansion. In fact, unlike wild-type T cells, PTENΔT CD4+ T cells are not anergized by delivery of TCR stimulation alone. These data suggest that by negatively regulating TCR signals, PTEN imposes a requirement for CD28 costimulation, thus defining a novel mechanism for its role in self-tolerance.
Combination of Vaccination and Chimeric Receptor Expressing T Cells Provides Improved Active Therapy of Tumors
Authors: Jiang Hui-Rong , Gilham David E. , Mulryan Kate , Kirillova Natalia , Hawkins Robert E. , Stern Peter L.
Published: April 2014

We have generated murine T cells expressing chimeric immune receptors (CR) against human 5T4 oncofetal Ag (h5T4) and evaluated their tumor therapeutic efficacy alone and in combination with immunization using a replication-defective adenovirus encoding h5T4 (Rad.h5T4) and bone marrow-derived dendritic cells (BMDC). The h5T4-specific engineered T cells demonstrated Ag-specific, non-MHC-restricted cytolysis of h5T4-positive B16 and CT26 tumor cells in vitro by cytotoxicity assay and antitumor activity in vivo using a Winn assay. In the s.c. injected B16h5T4 melanoma model, early local but not systemic i.v. administration of syngeneic h5T4-specific CR T cells significantly increased mice survival. This improvement was further enhanced when combined with immunization with Rad.h5T4, followed by post-CR T cell treatment with BMDC in the active therapy model, possibly through mechanisms of enhancing Ag-specific cellular immune responses. This synergistic effect was lost without delivery of the BMDC. Our findings suggest that combining engineered T cells with specific vaccination strategies can improve the active tumor therapy.
T Cell, Ig Domain, Mucin Domain-2 Gene-Deficient Mice Reveal a Novel Mechanism for the Regulation of Th2 Immune Responses and Airway Inflammation
Authors: Rennert Paul D. , Ichimura Takaharu , Sizing Irene D. , Bailly Veronique , Li Zhifang , Rennard Rachel , McCoon Patricia , Pablo Lourdes , Miklasz Steven , Tarilonte Leticia , Bonventre Joseph V.
Published: April 2014

The development of asthma and other atopic diseases is influenced by cytokines produced by Th2 effector T cells. How effector T cell responses are regulated once these cell populations are established remains unclear. The recently described T cell and airway phenotype regulator locus, containing the T cell, Ig domain, mucin domain (TIM) genes, is genetically associated with Th2 cytokine production and Th2-dependent immune responses. In this study, we report the phenotype of the TIM-2 gene-deficient mouse, and demonstrate exacerbated lung inflammation in an airway atopic response model. Immune responses in the TIM-2-deficient mouse reveal disregulated expression of Th2 cytokines, and adoptive transfer experiments show that the T cell compartment is responsible for the heightened inflammatory phenotype. These studies show that TIM-2 is a novel and critical regulator of effector T cell activity.
Identification and Characterization of the Precursors Committed to Osteoclasts Induced by TNF-Related Activation-Induced Cytokine/Receptor Activator of NF-κB Ligand
Authors: Mochizuki Ayako , Takami Masamichi , Kawawa Tadaharu , Suzumoto Reina , Sasaki Takahisa , Shiba Akihiko , Tsukasaki Hiroaki , Zhao Baohong , Yasuhara Rika , Suzawa Tetsuo , Miyamoto Yoichi , Choi Yongwon , Kamijo Ryutaro
Published: April 2014

Osteoclasts are terminally differentiated from cells of monocyte/macrophage lineage by stimulation with TNF-related activation-induced cytokine (TRANCE) (receptor activator of NF-κB ligand/osteoprotegerin ligand/osteoclast differentiation factor/TNFSF11/CD254). In the present study, we attempted to determine when and how the cell fate of precursors becomes committed to osteoclasts following TRANCE stimulation. Although mouse bone marrow-derived macrophages (BMMs) were able to differentiate into either osteoclasts or dendritic cells, the cells no longer differentiated into dendritic cells after treatment with TRANCE for 24 h, indicating that their cell fate was committed to osteoclasts. Committed cells as well as BMMs were still quite weak in tartrate-resistant acid phosphatase activity, an osteoclast marker, and incorporated zymosan particles by phagocytosis. Interestingly, committed cells, but not BMMs, could still differentiate into osteoclasts even after incorporation of the zymosan particles. Furthermore, IL-4 and IFN-γ, potent inhibitors of osteoclast differentiation, failed to inhibit osteoclast differentiation from committed cells, and blocking of TRANCE stimulation by osteoprotegerin resulted in cell death. Adhesion to culture plates was believed to be essential for osteoclast differentiation; however, committed cells, but not BMMs, differentiated into multinucleated osteoclasts without adhesion to culture plates. Although LPS activated the NF-κB-mediated pathway in BMMs as well as in committed cells, the mRNA expression level of TNF-α in the committed cells was significantly lower than that in BMMs. These results suggest that characteristics of the committed cells induced by TRANCE are distinctively different from that of BMMs and osteoclasts.
Blockade of CTLA-4 on CD4+CD25+ Regulatory T Cells Abrogates Their Function In Vivo
Authors: Read Simon , Greenwald Rebecca , Izcue Ana , Robinson Nicholas , Mandelbrot Didier , Francisco Loise , Sharpe Arlene H. , Powrie Fiona
Published: April 2014

Naturally occurring CD4+ regulatory T cells (TR) that express CD25 and the transcription factor FoxP3 play a key role in immune homeostasis, preventing immune pathological responses to self and foreign Ags. CTLA-4 is expressed by a high percentage of these cells, and is often considered as a marker for TR in experimental and clinical analysis. However, it has not yet been proven that CTLA-4 has a direct role in TR function. In this study, using a T cell-mediated colitis model, we demonstrate that anti-CTLA-4 mAb treatment inhibits TR function in vivo via direct effects on CTLA-4-expressing TR, and not via hyperactivation of colitogenic effector T cells. Although anti-CTLA-4 mAb treatment completely inhibits TR function, it does not reduce TR numbers or their homing to the GALT, suggesting the Ab mediates its function by blockade of a signal required for TR activity. In contrast to the striking effect of the Ab, CTLA-4-deficient mice can produce functional TR, suggesting that under some circumstances other immune regulatory mechanisms, including the production of IL-10, are able to compensate for the loss of the CTLA-4-mediated pathway. This study provides direct evidence that CTLA-4 has a specific, nonredundant role in the function of normal TR. This role has to be taken into account when targeting CTLA-4 for therapeutic purposes, as such a strategy will not only boost effector T cell responses, but might also break TR-mediated self-tolerance.
Cell-Autonomous CCL5 Transcription by Memory CD8 T Cells Is Regulated by IL-4
Authors: Marçais Antoine , Coupet Charles-Antoine , Walzer Thierry , Tomkowiak Martine , Ghittoni Raffaella , Marvel Jacqueline
Published: April 2014

Immunological memory is associated with the display of improved effector functions. The maintenance by CD8 memory cells of high levels of untranslated CCL5 mRNA allows these cells to immediately secrete this chemokine upon Ag stimulation. Untranslated mRNA storage is a newly described process supporting the immediate display of an effector function by memory lymphocytes. We have tested the capacity of different cytokines to regulate the memorization of CCL5 by memory CD8 T cells. We found that IL-4 treatment of murine CD8 T cells impairs immediate CCL5 secretion capacity by inhibiting CCL5 mRNA transcription through a STAT6-dependent pathway. The inhibition by IL-4 is reversible, as memory CD8 T cells reconstitute their CCL5 mRNA stores and reacquire their immediate CCL5 secretion capacity when IL-4 is withdrawn. This recovery is cell autonomous because it proceeds in culture medium in the absence of exogenous growth factors, suggesting that CCL5 expression by memory CD8 T cells is a default process. Overall, these results indicate that the expression of CCL5 is an intrinsic property acquired by memory CD8 T cells that is regulated by environmental factors.
B Cells Drive Early T Cell Autoimmunity In Vivo prior to Dendritic Cell-Mediated Autoantigen Presentation
Authors: Yan Jun , Harvey Bohdan P. , Gee Renelle J. , Shlomchik Mark J. , Mamula Mark J.
Published: April 2014

Both B cells and dendritic cells (DCs) have been implicated as autoantigen-presenting cells in the activation of self-reactive T cells. However, most self-proteins are ubiquitously and/or developmentally expressed, making it difficult to determine the source and the exposure of autoantigens to APCs in a controlled manner. In this study, we have used an Ig transgenic mouse model to examine the mechanisms by which B cells and other APCs acquire and present lupus autoantigens in vivo. Targeting a lupus autoantigen, the small nuclear ribonucleoprotein particle D protein, to the BCR activates autoreactive T cells in the periphery. Our in vivo studies demonstrate that autoantigen-specific B cells, when present in the repertoire, are the first subset of APCs to capture and present self-proteins for activating T cells. Thereafter, DCs acquire self-Ag and become effective APCs for stimulating the same subsets of autoreactive T cells. This mechanism provides one explanation of how early steps in autoimmunity can focus responses, via BCR, at a small group of self-proteins among the total milieu of intracellular self-proteins. Subsequently, DCs and other professional APCs may then amplify and perpetuate the autoimmune T cell response.
Rac1 Negatively Regulates Lipopolysaccharide-Induced IL-23 p19 Expression in Human Macrophages and Dendritic Cells and NF-κB p65 trans Activation Plays a Novel Role
Authors: Utsugi Mitsuyoshi , Dobashi Kunio , Ishizuka Tamotsu , Kawata Tadayoshi , Hisada Takeshi , Shimizu Yasuo , Ono Akihiro , Mori Masatomo
Published: April 2014

IL-23 is a heterodimeric cytokine composed of a unique p19 subunit and of a p40 subunit that is also common to IL-12. We defined the distinct signaling mechanisms that regulate the LPS-mediated induction of IL-23 p19 and p40 in human macrophages and dendritic cells. We found that the overexpression of dominant-negative Rac1 (N17Rac1) enhanced LPS-induced IL-23 p19 expression but did not alter p40 expression or IL-12 p70 production in PMA-treated THP-1 macrophages and in human monocyte-derived dendritic cells. Although the inhibition of either p38 MAPK or JNK enhanced LPS-induced p19 expression, N17Rac1 did not influence either p38 MAPK or JNK activation. By contrast, N17Rac1 augmented both NF-κB gene expression and p65 trans activation stimulated by LPS without affecting the degradation of IκB-α or DNA binding to NF-κB. Furthermore, small interference RNA of NF-κB p65 attenuated cellular amounts of p65 and suppressed LPS-induced p19 expression but did not affect p40 expression. Our findings indicate that Rac1 negatively controls LPS-induced IL-23 p19 expression through an NF-κB p65 trans activation-dependent, IκB-independent pathway and that NF-κB p65 regulates LPS-induced IL-23 p19, but not p40, expression, which causes differences in the control of IL-23 p19 and p40 expression by Rac1.
Structural Characterization of Mycobacterial Phosphatidylinositol Mannoside Binding to Mouse CD1d
Authors: Zajonc Dirk M. , Ainge Gary D. , Painter Gavin F. , Severn Wayne B. , Wilson Ian A.
Published: April 2014

Mycobacterial phosphatidylinositol tetramannosides (PIM4) are agonists for a distinct population of invariant human (Vα24) and mouse (Vα14) NKT cells, when presented by CD1d. We determined the crystal structure at 2.6-Å resolution of mouse CD1d bound to a synthetic dipalmitoyl-PIM2. Natural PIM2, which differs in its fatty acid composition is a biosynthetic precursor of PIM4, PIM6, lipomannan, and lipoarabinomannan. The PIM2 headgroup (inositol-dimannoside) is the most complex to date among all the crystallized CD1d ligands and is remarkably ordered in the CD1d binding groove. A specific hydrogen-bonding network between PIM2 and CD1d orients the headgroup in the center of the binding groove and above the A′ pocket. A central cluster of hydrophilic CD1d residues (Asp153, Thr156, Ser76, Arg79) interacts with the phosphate, inositol, and α1–α6-linked mannose of the headgroup, whereas additional specificity for the α1- and α2-linked mannose is conferred by Thr159. The additional two mannoses in PIM4, relative to PIM2, are located at the distal 6′ carbon of the α1-α6-linked mannose and would project away from the CD1d binding groove for interaction with the TCR. Compared with other CD1d-sphingolipid structures, PIM2 has an increased number of polar interactions between its headgroup and CD1, but reduced specificity for the diacylglycerol backbone. Thus, novel NKT cell agonists can be designed that focus on substitutions of the headgroup rather than on reducing lipid chain length, as in OCH and PBS-25, two potent variants of the highly stimulatory invariant NKT cell agonist α-galactosylceramide.
Repression of IFN-γ Induction of Class II Transactivator: A Role for PRDM1/Blimp-1 in Regulation of Cytokine Signaling
Authors: Tooze Reuben M. , Stephenson Sophie , Doody Gina M.
Published: April 2014

MHC class II is expressed in restricted lineages and is modulated in response to pathogens and inflammatory stimuli. This expression is controlled by MHC CIITA, which is transcribed from multiple promoters. Although factors required for induction of CIITA are well characterized, less is known about the mechanisms leading to repression of this gene. During plasma cell differentiation, B lymphocyte-induced maturation protein-1 (PRDM1/Blimp-1) represses promoter (p)III of CIITA, responsible for constitutive expression in B cells. pIV is inducible by IFN-γ in epithelia, macrophages and B cells. An IFN regulatory factor-element (IRF-E) in CIITA-pIV, which is bound by IRF-1 and IRF-2, is necessary for this response. This site matches the PRDM1/Blimp-1 consensus binding site, and PRDM1/Blimp-1 is expressed in cell lineages in which this promoter is operative. We, therefore, investigated whether PRDM1 regulates CIITA-pIV and found that PRDM1 bound to CIITA-pIV in vivo and the IRF-E in vitro. PRDM1 repressed IFN-γ-mediated induction of a CIITA-pIV luciferase reporter in a fashion dependent on an intact consensus sequence and competes with IRF-1/IRF-2 for binding to the IRF-E and promoter activation. In human myeloma cell lines that express IRFs, PRDM1 occupancy of CIITA-pIV was associated with resistance to IFN-γ stimulation, while short interfering RNA knockdown of PRDM1 led to up-regulation of CIITA. Our data indicate that PRDM1 is a repressor of CIITA-pIV, identifying a target of particular relevance to macrophages and epithelia. These findings support a model in which PRDM1/Blimp-1 can modulate the cellular response to IFN-γ by competing with IRF-1/IRF-2 dependent activation of target promoters.
Inhibition of IL-2 Induced IL-10 Production as a Principle of Phase-Specific Immunotherapy
Authors: Bodas Manish , Jain Nitya , Awasthi Amit , Martin Sunil , Penke Loka Raghu Kumar , Dandekar Dineshkumar , Mitra Debashis , Saha Bhaskar
Published: April 2014

Leishmania donovani, a protozoan parasite, inflicts a fatal disease, visceral leishmaniasis. The suppression of antileishmanial T cell responses that characterizes the disease was proposed to be due to deficiency of a T cell growth factor, IL-2. We demonstrate that during the first week after L. donovani infection, IL-2 induces IL-10 that suppresses the host-protective functions of T cells 14 days after infection. The observed suppression is concurrent with increased CD4+glucocorticoid-induced TNF receptor+ T cells and Foxp3 expression in BALB/c mice, implicating IL-2-dependent regulatory T cell control of antileishmanial immune responses. Indeed, IL-2 and IL-10 neutralization at different time points after the infection demonstrates their distinct roles at the priming and effector phases, respectively, and establishes kinetic modulation of ongoing immune responses as a principle of a rational, phase-specific immunotherapy.
IL-17 Production Is Dominated by γδ T Cells rather than CD4 T Cells during Mycobacterium tuberculosis Infection
Authors: Lockhart Euan , Green Angela M. , Flynn JoAnne L.
Published: April 2014

IL-17 is a cytokine produced by T cells in response to IL-23. Recent data support a new subset of CD4 Th cells distinct from Th1 or Th2 cells that produce IL-17 and may contribute to inflammation. In this study, we demonstrate that, in naive mice, as well as during Mycobacterium tuberculosis infection, IL-17 production is primarily from γδ T cells and other non-CD4+CD8+ cells, rather than CD4 T cells. The production of IL-17 by these cells is stimulated by IL-23 alone, and strongly induced by the cytokines, including IL-23, produced by M. tuberculosis-infected dendritic cells. IL-23 is present in the lungs early in infection and the IL-17-producing cells, such as γδ T cells, may represent a central innate protective response to pulmonary infection.
Murine γ-Herpesvirus 68 Limits Naturally Occurring CD4+CD25+ T Regulatory Cell Activity following Infection
Authors: Gasper-Smith Nancy , Marriott Ian , Bost Kenneth L.
Published: April 2014

During microbial infections, naturally occurring CD4+CD25+ T regulatory cells can suppress protective host responses or they can limit pathogen-induced inflammatory responses. The particular role played by these cells seems to depend upon the infectious agent being investigated. γ-Herpesviruses are efficacious pathogens which are well-known for their ability to induce lymphoproliferative disease and to establish latency in the host. However, no studies have investigated the importance of naturally occurring CD4+CD25+ T regulatory cells during infection with these viruses. Using the murine model of γ-herpesvirus infection, murine γ-herpesvirus 68 (γHV-68), we were surprised to find that levels of the CD4+CD25+ T regulatory cell transcript, FoxP3, continued to decrease as viral latency increased and as the leukocytosis phase of the disease progressed. Consistent with these results, the decrease in FoxP3 protein expression followed similar kinetics. Along with the reduced expression of this regulatory T cell marker, we also observed diminished CD4+CD25+ T regulatory cell activity in these cells isolated from γHV-68-infected animals. Dendritic cells infected in vitro with γHV-68 did not alter the ability of normal CD4+CD25+ regulatory T cells to limit the proliferation of CD4+ Th cells following stimulation. Taken together, these studies demonstrate a decreased presence and activity of CD4+CD25+ T regulatory cells during the mononucleosis-like phase of this viral infection. These alterations in naturally occurring T regulatory cell function may help to explain the dysregulation of the host’s immune response which allows the uncontrolled expansion of leukocytes as viral latency is established.
TLR3 Ligation Activates an Antiviral Response in Human Fetal Astrocytes: A Role for Viperin/cig5
Authors: Rivieccio Mark A. , Suh Hyeon-Sook , Zhao Yongmei , Zhao Meng-Liang , Chin Keh Chuang , Lee Sunhee C. , Brosnan Celia F.
Published: April 2014

TLR3 functions as a viral nucleic acid sentinel activated by dsRNA viruses and virus replication intermediates within intracellular vesicles. To explore the spectrum of genes induced in human astrocytes by TLR3, we used a microarray approach and the analog polyriboinosinic polyribocytidylic acid (pIC) as ligand. As expected for TLR activation, pIC induced a wide array of cytokines and chemokines known for their role in inflammatory responses, as well as up-regulation of the receptor itself. The data also showed activation of a broad spectrum of antiviral response genes. To determine whether pIC induced an antiviral state in astrocytes, a pseudotyped HIV viral particle, vesicular stomatitis virus g-env-HIV-1, was used. pIC significantly abrogated HIV-1 replication, whereas IL-1, which also potently activates astrocytes, did not. One of the most highly up-regulated genes on microarray was the protein viperin/cig5. We found that viperin/cig5 expression was dependent on IFN regulatory factor 3 and NF-κB signaling, and that repetitive stimulation with pIC, but not IL-1, further increased expression. Viperin induction could also be substantially inhibited by neutralizing Abs to IFN-β, as could HIV-1 replication. To explore a role for viperin in IFN-β-mediated inhibition of HIV-1, we used an RNA interference (RNAi) approach. RNAi directed against viperin, but not a scrambled RNAi, significantly inhibited viperin expression, and also significantly reversed pIC-induced inhibition of HIV-1 replication. We conclude that viperin contributes to the antiviral state induced by TLR3 ligation in astrocytes, supporting a role for astrocytes as part of the innate immune response against infection in the CNS.
The Monoclonal Antibody CHO-131 Identifies a Subset of Cutaneous Lymphocyte-Associated Antigen T Cells Enriched in P-Selectin-Binding Cells
Authors: Ni Zhenya , Campbell James J. , Niehans Gloria , Walcheck Bruce
Published: April 2014

T cells use the vascular adhesion molecules E- and P-selectin to enter inflamed skin. Previous studies have indicated the possibility for diversity in the synthesis of E- and P-selectin glycan ligands by activated T cells due to their different requirements for the O-glycan branching enzyme core 2 β1,6-N-acetylglucosaminyltransferase I and its independent regulation. It is known that T cell staining by the mAb HECA-452 (referred to as cutaneous lymphocyte-associated Ag (CLA) T cells) correlates with E-selectin binding, yet whether these cells uniformly bind P-selectin is less clear. The mAb CHO-131 and P-selectin binding require a glycan moiety consisting of a sialylated and fucosylated oligosaccharide properly positioned on a core-2 O-glycan. Interestingly, CHO-131 stains a subset of CLA+ T cells. A direct comparison of the selectin binding capacity of CHO-131+ and CHO-131− CLA+ T cells revealed a significantly greater P-selectin, but not E-selectin, binding activity by the former subset. Based on the expression of homing and central and effector memory cell markers, CHO-131+ and CHO-131− CLA+ T cells have an overlapping skin-tropic and memory phenotype. CHO-131+ T cells were considerably enriched in psoriatic skin, yet, unlike the peripheral blood of healthy individuals, HECA-452 and CHO-131 stained a similar proportion of T cells in the cutaneous lesions, indicating an accumulation advantage by CHO-131+ T cells. We conclude that the CHO-131+CLA+ T cell subset is enriched in P-selectin binding cells. These findings should provide new insights into the regulation and function of skin homing T cells.
A Novel C5a Receptor-Tissue Factor Cross-Talk in Neutrophils Links Innate Immunity to Coagulation Pathways
Authors: Ritis Konstantinos , Doumas Michael , Mastellos Dimitrios , Micheli Anastasia , Giaglis Stavros , Magotti Paola , Rafail Stavros , Kartalis Georgios , Sideras Paschalis , Lambris John D.
Published: April 2014

Neutrophils and complement are key sentinels of innate immunity and mediators of acute inflammation. Recent studies have suggested that inflammatory processes modulate thrombogenic pathways. To date, the potential cross-talk between innate immunity and thrombosis and the precise molecular pathway by which complement and neutrophils trigger the coagulation process have remained elusive. In this study, we demonstrate that antiphospholipid Ab-induced complement activation and downstream signaling via C5a receptors in neutrophils leads to the induction of tissue factor (TF), a key initiating component of the blood coagulation cascade. TF expression by neutrophils was associated with an enhanced procoagulant activity, as verified by a modified prothrombin time assay inhibited by anti-TF mAb. Inhibition studies using the complement inhibitor compstatin revealed that complement activation is triggered by antiphospholipid syndrome (APS) IgG and leads to the induction of a TF-dependent coagulant activity. Blockade studies using a selective C5a receptor antagonist and stimulation of neutrophils with recombinant human C5a demonstrated that C5a, and its receptor C5aR, mediate the expression of TF in neutrophils and thereby significantly enhance the procoagulant activity of neutrophils exposed to APS serum. These results identify a novel cross-talk between the complement and coagulation cascades that can potentially be exploited therapeutically in the treatment of APS and other complement-associated thrombotic diseases.
Regulation of IL-1 and TNF Receptor Expression and Function by Endogenous Macrophage Migration Inhibitory Factor
Authors: Toh Myew-Ling , Aeberli Daniel , Lacey Derek , Yang Yuan , Santos Leilani L. , Clarkson Michael , Sharma Laveena , Clyne Colin , Morand Eric F.
Published: April 2014

Macrophage migration inhibitory factor (MIF) has a key role in regulation of innate and adaptive immunity and is implicated in sepsis, tumorigenesis, and autoimmune disease. MIF deficiency or immunoneutralization leads to protection against fatal endotoxic, exotoxic, and infective shock, and anti-inflammatory effects in other experimental models of inflammatory disease. We report a novel regulatory role of MIF in type 1 IL-1R and p55 TNFR expression and function. Compared with wild-type cells, MIF-deficient cells were hyporesponsive to IL-1- and TNF-induced MAPK activity, AP-1 activity, and cellular proliferation, while NF-κB function was preserved. Hyporesponsiveness of MIF-deficient cells was associated with down-regulation of cytokine receptor expression, which was restored by reconstitution of either an upstream kinase of MAPK, MAPK/ERK kinase, or MIF. These data suggest that endogenous MIF is required for cytokine activation of MAPK/AP-1 and cytokine receptor expression. This autocrine regulatory pathway defines an important amplifying role of endogenous MIF in cytokine-mediated immune and inflammatory diseases and provides further molecular evidence for the critical role of MIF in cellular activation.