bluuebunny/crossref_metadata_2025 huggingface dataset:
Adenosine Acts through A2 Receptors to Inhibit IL-2-Induced Tyrosine Phosphorylation of STAT5 in T Lymphocytes: Role of Cyclic Adenosine 3′,5′-Monophosphate and Phosphatases
Authors: Zhang Hong , Conrad David M. , Butler Jared J. , Zhao Chuanli , Blay Jonathan , Hoskin David W.
Published: April 2014

Adenosine is a purine nucleoside with immunosuppressive activity that acts through cell surface receptors (A1, A2a, A2b, A3) on responsive cells such as T lymphocytes. IL-2 is a major T cell growth and survival factor that is responsible for inducing Jak1, Jak3, and STAT5 phosphorylation, as well as causing STAT5 to translocate to the nucleus and bind regulatory elements in the genome. In this study, we show that adenosine suppressed IL-2-dependent proliferation of CTLL-2 T cells by inhibiting STAT5a/b tyrosine phosphorylation that is associated with IL-2R signaling without affecting IL-2-induced phosphorylation of Jak1 or Jak3. The inhibitory effect of adenosine on IL-2-induced STAT5a/b tyrosine phosphorylation was reversed by the protein tyrosine phosphatase inhibitors sodium orthovanadate and bpV(phen). Adenosine dramatically increased Src homology region 2 domain-containing phosphatase-2 (SHP-2) tyrosine phosphorylation and its association with STAT5 in IL-2-stimulated CTLL-2 T cells, implicating SHP-2 in adenosine-induced STAT5a/b dephosphorylation. The inhibitory effect of adenosine on IL-2-induced STAT5a/b tyrosine phosphorylation was reproduced by A2 receptor agonists and was blocked by selective A2a and A2b receptor antagonists, indicating that adenosine was mediating its effect through A2 receptors. Inhibition of STAT5a/b phosphorylation was reproduced with cell-permeable 8-bromo-cAMP or forskolin-induced activation of adenylyl cyclase, and blocked by the cAMP/protein kinase A inhibitor Rp-cAMP. Forskolin and 8-bromo-cAMP also induced SHP-2 tyrosine phosphorylation. Collectively, these findings suggest that adenosine acts through A2 receptors and associated cAMP/protein kinase A-dependent signaling pathways to activate SHP-2 and cause STAT5 dephosphorylation that results in reduced IL-2R signaling in T cells.
SHP-1 and SHP-2 Associate with Immunoreceptor Tyrosine-Based Switch Motif of Programmed Death 1 upon Primary Human T Cell Stimulation, but Only Receptor Ligation Prevents T Cell Activation
Authors: Chemnitz Jens M. , Parry Richard V. , Nichols Kim E. , June Carl H. , Riley James L.
Published: April 2014

To study the cis- and trans-acting factors that mediate programmed death 1 (PD-1) signaling in primary human CD4 T cells, we constructed a chimeric molecule consisting of the murine CD28 extracellular domain and human PD-1 cytoplasmic tail. When introduced into CD4 T cells, this construct mimics the activity of endogenous PD-1 in terms of its ability to suppress T cell expansion and cytokine production. The cytoplasmic tail of PD-1 contains two structural motifs, an ITIM and an immunoreceptor tyrosine-based switch motif (ITSM). Mutation of the ITIM had little effect on PD-1 signaling or functional activity. In contrast, mutation of the ITSM abrogated the ability of PD-1 to block cytokine synthesis and to limit T cell expansion. Further biochemical analyses revealed that the ability of PD-1 to block T cell activation correlated with recruitment of Src homology region 2 domain-containing phosphatase-1 (SHP-1) and SHP-2, and not the adaptor Src homology 2 domain-containing molecule 1A, to the ITSM domain. In TCR-stimulated T cells, SHP-2 associated with PD-1, even in the absence of PD-1 engagement. Despite this interaction, the ability of PD-1 to block T cell activation required receptor ligation, suggesting that colocalization of PD-1 with CD3 and/or CD28 may be necessary for inhibition of T cell activation.
T Cell Biasing by Activated Dendritic Cells
Authors: Anderson Charles F. , Lucas Mark , Gutiérrez-Kobeh Laila , Field Ann E. , Mosser David M.
Published: April 2014

We have previously reported that the ligation of FcγRs on activated macrophages affected their production of cytokines and their ability to influence T cell activation. Dendritic cells (DC) are important APCs that also express FcγR. In the present work, we sought to determine whether DC responded to immune complexes in a manner similar to macrophages. We confirmed that activated murine DC produced IL-12, and, as a result, induced naive T cells to produce primarily IFN-γ upon stimulation. However, DC activated in the presence of immune complexes shut off their production of IL-12p70 and induced a Th2-like cytokine response. Thus, DC respond to immune complexes by altering their cytokine production, which, in turn, influences T cell responses. A DC transfer experiment was performed to determine the extent that APC exposure to immune complexes could influence adaptive immune responses. Vaccination of mice with Ag, along with DC that were activated in the presence of immune complexes, resulted in higher levels of Ag-specific IgG1 Ab, relative to mice that were vaccinated with activated DC and Ag alone. The mechanism by which DC altered their cytokine production in response to immune complexes was different from macrophages. Macrophages down-regulated the transcription of both the p40 and p35 subunits of IL-12, whereas DC decreased only p35 expression. We conclude that APCs expressing FcγR on their surface can respond to immune complexes by shutting off IL-12 biosynthesis, to prevent the Th1-type T cell biasing that normally accompanies innate immune activation.
TGF-β1 Disrupts Endotoxin Signaling in Microglial Cells through Smad3 and MAPK Pathways
Authors: Le Yingying , Iribarren Pablo , Gong Wanghua , Cui Youhong , Zhang Xia , Wang Ji Ming
Published: April 2014

Human formyl peptide receptor-like 1 and its mouse homologue formyl peptide receptor 2 (FPR2) are G protein-coupled receptors used by a number of exogenous and host-derived chemotactic peptides, including the 42 aa form of β amyloid peptide, a causative factor of Alzheimer’s disease. Functional FPR2 was induced by bacterial LPS in murine microglial cells, the resident phagocytic cells that play a pivotal role in inflammatory and immunological diseases in the CNS. To identify agents that may suppress microglial cell activation under proinflammatory conditions, we investigated the effect of TGF-β1 on the expression of functional FPR2 by microglial cells activated by LPS. TGF-β1 dose-dependently inhibited the mRNA expression and function of FPR2 in LPS-activated microglial cells. The inhibitory effect of TGF-β1 was mediated by Smad3, a key signaling molecule coupled to the TGF-β receptor, and the transcription coactivator, p300. Also, TGF-β1 activates MAPKs in microglial cells that became refractory to further stimulation by LPS. These effects of TGF-β1 culminate in the inhibition of LPS-induced activation of NF-κB and the up-regulation of FPR2 in microglial cells. Thus, TGF-β1 may exert a protective role in CNS diseases characterized by microglial cell activation by proinflammatory stimulants.
Fully Functional Memory CD8 T Cells in the Absence of CD4 T Cells
Authors: Marzo Amanda L. , Vezys Vaiva , Klonowski Kimberly D. , Lee Seung-Joo , Muralimohan Guruprasaadh , Moore Meagan , Tough David F. , Lefrançois Leo
Published: April 2014

The role of CD4 T cells in providing help to CD8 T cells in primary and secondary responses to infection remains controversial. Using recombinant strains of virus and bacteria expressing the same Ag, we determined the requirement for CD4 T cells in endogenous CD8 T cell responses to infection with vesicular stomatitis virus and Listeria monocytogenes (LM). Depletion of CD4 T cells had no effect on the frequency of primary or secondary vesicular stomatitis virus-specific CD8 T cells in either lymphoid or nonlymphoid tissues. In contrast, the primary LM-specific CD8 T cell response was CD4 T cell dependent. Surprisingly, the LM-specific CD8 T cell recall response was also CD4 T cell dependent, which correlated with a requirement for CD40/CD40L interactions. However, concomitant inhibition of CD40L and CD4 T cell removal revealed that these pathways may be operating independently. Importantly, despite the absence of CD4 T cells during the recall response or throughout the entire response, CD8 memory T cells were functional effectors and proliferated equivalently to their “helped” counterparts. These data call into question the contention that CD4 T cells condition memory CD8 T cells during the primary response and indicate that the principal role of CD4 T cells in generating CD8 memory cells after infection is augmentation of proliferation or survival through costimulatory signals.
Nucleolin Is a Second Component of the CD154 mRNA Stability Complex That Regulates mRNA Turnover in Activated T Cells
Authors: Singh Karnail , Laughlin Jennifer , Kosinski Penelope A. , Covey Lori R.
Published: April 2014

CD154 (CD40L) mRNA turnover is regulated in part at the posttranscriptional level by a protein complex (termed Complex I) that binds to a highly CU-rich region of the 3′UTR. Polypyrimidine tract-binding protein (PTB) has previously been identified as a major RNA-binding protein in Complex I. Nondenaturing gel filtration of total extract from Jurkat T cells demonstrated that the CD154 mRNA-binding activity migrates as a ∼200-kDa complex, indicating the presence of multiple complex-associated proteins. We have currently undertaken a biochemical approach to further characterize Complex I and observed that it segregates over DEAE-Sepharose into two subcomplexes (termed I-L and I-U). Furthermore, nucleolin was identified as a component of both subcomplexes and was shown that it is the major RNA-binding protein in I-U. To directly demonstrate the biological significance of Complex I binding to the CD154 transcript, cytoplasm from human Jurkat cells was fractionated over a sucrose gradient and the different cellular fractions subjected to immunoprecipitation with anti-PTB and anti-nucleolin Abs. RT-PCR of the immunoprecipitated products using CD154-specific primers clearly demonstrated that nucleolin and PTB are associated with CD154 mRNA in both the ribonucleoprotein and polysome fractions. These data strongly support a model whereby nucleolin and PTB are integral to the stability of CD154 mRNA and are components of the CD154 ribonucleoprotein particle associated with actively translating ribosomes.
Kinase Suppressor of Ras Couples Ras to the ERK Cascade during T Cell Development
Authors: Laurent Micheline N. , Ramirez Danny Maria , Alberola-Ila José
Published: April 2014

Ras signaling is critical for many developmental processes and requires the precise coordination of interactions among multiple downstream components. One mechanism by which this regulation is achieved is through the use of scaffolding molecules that coordinate the assembly of multimolecular complexes. Recently, the scaffolding molecule kinase suppressor of Ras (KSR) was isolated in genetic screens as a modifier of Ras signaling, although its contribution to regulating Ras-mediated activation of its different downstream effectors is not well understood. We have analyzed the role of KSR in linking Ras to the ERK cascade during positive selection. Our results demonstrate that KSR overexpression interferes with T cell development, an effect that requires the direct interaction between KSR and MEK. This functional effect correlates with the ability of KSR to uncouple Ras from the ERK cascade when overexpressed.
FcR Interactions Do Not Play a Major Role in Inhibition of Experimental Autoimmune Encephalomyelitis by Anti-CD154 Monoclonal Antibodies
Authors: Nagelkerken Lex , Haspels Inge , van Rijs Wouter , Blauw Bep , Ferrant Janine L. , Hess Donna M. , Garber Ellen A. , Taylor Fred R. , Burkly Linda C.
Published: April 2014

It has been demonstrated that anti-CD154 mAb treatment effectively inhibits the development of experimental autoimmune encephalomyelitis (EAE). However, although it appears to prevent the induction of Th1 cells and reactivation of encephalitogenic T cells within the CNS, little information is available regarding the involvement of alternative mechanisms, nor has the contribution of Fc effector mechanisms in this context been addressed. By contrast, efficacy of anti-CD154 mAbs in models of allotransplantation has been reported to involve long-term unresponsiveness, potentially via activation of T regulatory cells, and recently was reported to depend on Fc-dependent functions, such as activated T cell depletion through FcγR or complement. In this study we demonstrate that anti-CD154 mAb treatment inhibits EAE development in SJL mice without apparent long-term unresponsiveness or active suppression of disease. To address whether the mechanism of inhibition of EAE by anti-CD154 mAb depends on its Fc effector interactions, we compared an anti-CD154 mAb with its aglycosyl counterpart with severely impaired FcγR binding and reduced complement binding activity with regard to their ability to inhibit clinical signs of EAE and report that both forms of the Ab are similarly protective. This observation was largely confirmed by the extent of leukocyte infiltration of the CNS; however, mice treated with the aglycosyl form may display slightly more proteolipid protein 139–151-specific immune reactivity. It is concluded that FcR interactions do not play a major role in the protective effect of anti-CD154 mAb in the context of EAE, though they may contribute to the full abrogation of peripheral peptide-specific lymphocyte responses.
Genetic Control of Autoimmunity: Protection from Diabetes, but Spontaneous Autoimmune Biliary Disease in a Nonobese Diabetic Congenic Strain
Authors: Koarada Syuichi , Wu Yuehong , Fertig Noreen , Sass David A. , Nalesnik Michael , Todd John A. , Lyons Paul A. , Fenyk-Melody Judith , Rainbow Daniel B. , Wicker Linda S. , Peterson Laurence B. , Ridgway William M.
Published: April 2014

At least 20 insulin-dependent diabetes (Idd) loci modify the progression of autoimmune diabetes in the NOD mouse, an animal model of human type 1 diabetes. The NOD.c3c4 congenic mouse, which has multiple B6- and B10-derived Idd-resistant alleles on chromosomes 3 and 4, respectively, is completely protected from autoimmune diabetes. We demonstrate in this study, however, that NOD.c3c4 mice develop a novel spontaneous and fatal autoimmune polycystic biliary tract disease, with lymphocytic peribiliary infiltrates and autoantibodies. Strains having a subset of the Idd-resistant alleles present in the NOD.c3c4 strain show component phenotypes of the liver disease: NOD mice with B6 resistance alleles only on chromosome 3 have lymphocytic liver infiltration without autoantibody formation, while NOD mice with B10 resistance alleles only on chromosome 4 show autoantibody formation without liver infiltration. The liver disease is transferable to naive NOD.c3c4 recipients using splenocytes from affected NOD.c3c4 mice, demonstrating an autoimmune etiology. Thus, substitution of non-NOD genetic intervals into the NOD strain can prevent diabetes, but in turn cause an entirely different autoimmune syndrome, a finding consistent with a generalized failure of self-tolerance in the NOD genetic background. The complex clinical phenotypes in human autoimmune conditions may be similarly resolved into largely overlapping biochemical pathways that are then modified, potentially by alleles at a few key chromosomal regions, to produce specific autoimmune syndromes.
TIRC7 Deficiency Causes In Vitro and In Vivo Augmentation of T and B Cell Activation and Cytokine Response
Authors: Utku Nalân , Boerner Anke , Tomschegg Antje , Bennai-Sanfourche Fatima , Bulwin Grit-Carsta , Heinemann Thomas , Loehler Jürgen , Blumberg Richard S. , Volk Hans-Dieter
Published: April 2014

The membrane protein T cell immune response cDNA 7 (TIRC7) was recently identified and was shown to play an important role in T cell activation. To characterize the function of TIRC7 in more detail, we generated TIRC7-deficient mice by gene targeting. We observed disturbed T and B cell function both in vitro and in vivo in TIRC7−/− mice. Histologically, primary and secondary lymphoid organs showed a mixture of hypo-, hyper-, and dysplastic changes of multiple lymphohemopoietic compartments. T cells from TIRC7−/− mice exhibited significantly increased proliferation and expression of IL-2, IFN-γ, and IL-4 in response to different stimuli. Resting T cells from TIRC7−/− mice exhibited decreased CD62L, but increased CD11a and CD44 expression, suggesting an in vivo expansion of memory/effector T cells. Remarkably, activated T cells from TIRC7−/− mice expressed lower levels of CTLA-4 in comparison with wild-type cells. B cells from TIRC7-deficient mice exhibited significantly higher in vitro proliferation following stimulation with anti-CD40 Ab or LPS plus IL-4. B cell hyperreactivity was reflected in vivo by elevated serum levels of various Ig classes and higher CD86 expression on B cells. Furthermore, TIRC7 deficiency resulted in an augmented delayed-type hypersensitivity response that was also reflected in increased mononuclear infiltration in the skin obtained from TIRC7-deficient mice food pads. In summary, the data strongly support an important role for TIRC7 in regulating both T and B cell responses.
Initiation of Immune Responses in Brain Is Promoted by Local Dendritic Cells
Authors: Karman Jozsef , Ling Changying , Sandor Matyas , Fabry Zsuzsanna
Published: April 2014

The contribution of dendritic cells (DCs) to initiating T cell-mediated immune response in and T cell homing into the CNS has not yet been clarified. In this study we show by confocal microscopy and flow cytometry that cells expressing CD11c, CD205, and MHC class II molecules and containing fluorescently labeled, processed Ag accumulate at the site of intracerebral Ag injection. These cells follow a specific pattern upon migrating out of the brain. To track their pathway out of the CNS, we differentiated DCs from bone marrow of GFP-transgenic mice and injected them directly into brains of naive C57BL/6 mice. We demonstrate that DCs migrate from brain to cervical lymph nodes, a process that can be blocked by fixation or pertussis toxin treatment of the DCs. Injection of OVA-loaded DCs into brain initiates a SIINFEKL (a dominant OVA epitope)-specific T cell response in lymph nodes and spleen, as measured by specific tetramer and LFA-1 activation marker staining. Additionally, a fraction of activated SIINFEKL-specific T cells home to the CNS. Specific T cell homing to the CNS, however, cannot be induced by i.v. injection of OVA-loaded DCs alone. These data suggest that brain-emigrant DCs are sufficient to support activated T cells to home to the tissue of DC origination. Thus, initiation of immune reactivity against CNS Ags involves the migration of APCs from nervous tissue to peripheral lymphoid tissues, similarly to that in other organs.
Identification of Multiple Cell Cycle Regulatory Functions of p57Kip2 in Human T Lymphocytes
Authors: Li Guiming , Domenico Joanne , Lucas Joseph J. , Gelfand Erwin W.
Published: April 2014

The specific functions of p57Kip2 in lymphocytes have not yet been fully elucidated. In this study, it is shown that p57Kip2, which is a member of the Cip/Kip family of cyclin-dependent kinase inhibitors, is present in the nuclei of normal resting (G0) T cells from peripheral blood and in the nuclei of the T cell-derived Jurkat cell line. Activation through the TCR results in rapid transport of cytoplasmic cyclin-dependent kinase 6 (cdk6) to nuclei, where it associates with cyclin D and p57Kip2 in active enzyme complexes. Using purified recombinant proteins, it was shown in vitro that addition of p57Kip2 protein to a mixture of cyclin D2 and cdk6 enhanced the association of the latter two proteins and resulted in phosphorylation of p57Kip2. To probe further the function of p57Kip2, Jurkat cells stably transfected with a plasmid encoding p57Kip2 under control of an inducible (tetracycline) promoter were made. Induction of p57Kip2 resulted in increased association of cdk6 with cyclin D3, without receptor-mediated T cell stimulation. The overall amounts of cdk6 and cyclin D3, and also of cdk4 and cyclin E, remained unchanged. Most notably, increased p57Kip2 levels resulted in marked inhibition of both cyclin E- and cyclin A-associated cdk2 kinase activities and a decrease in cyclin A amounts. Therefore, although facilitating activation of cdk6, the ultimate outcome of p57Kip2 induction was a decrease in DNA synthesis and cell proliferation. The results indicate that p57Kip2 is involved in the regulation of several aspects of the T cell cycle.
Estrogen Receptor α Signaling in Inflammatory Leukocytes Is Dispensable for 17β-Estradiol-Mediated Inhibition of Experimental Autoimmune Encephalomyelitis
Authors: Garidou Lucile , Laffont Sophie , Douin-Echinard Victorine , Coureau Christiane , Krust Andrée , Chambon Pierre , Guéry Jean-Charles
Published: April 2014

Estrogen treatment has been shown to exert a protective effect on experimental autoimmune encephalomyelitis (EAE), and is under clinical trial for multiple sclerosis. Although it is commonly assumed that estrogens exert their effect by modulating immune functions, we show in this study that 17β-estradiol (E2) treatment can inhibit mouse EAE without affecting autoantigen-specific T cell responsiveness and type 1 cytokine production. Using mutant mice in which estrogen receptor α (ERα) has been unambiguously inactivated, we found that ERα was responsible for the E2-mediated inhibition of EAE. We next generated irradiation bone marrow chimeras in which ERα expression was selectively impaired in inflammatory T lymphocytes or was limited to the radiosensitive hemopoietic compartment. Our data show that the protective effect of E2 on clinical EAE and CNS inflammation was not dependent on ERα signaling in inflammatory T cells. Likewise, EAE development was not prevented by E2 treatment in chimeric mice that selectively expressed ERα in the systemic immune compartment. In conclusion, our data demonstrate that the beneficial effect of E2 on this autoimmune disease does not involve ERα signaling in blood-derived inflammatory cells, and indicate that ERα expressed in other tissues, such as CNS-resident microglia or endothelial cells, mediates this effect.
Early Expression of a Functional TCRβ Chain Inhibits TCRγ Gene Rearrangements without Altering the Frequency of TCRγδ Lineage Cells
Authors: Gerber David , Boucontet Laurent , Pereira Pablo
Published: April 2014

To investigate the consequences of the simultaneous expression in progenitor cells of a TCRγδ and a pre-TCR on αβ/γδ lineage commitment, we have forced expression of functionally rearranged TCRβ, TCRγ, and TCRδ chains by means of transgenes. Mice transgenic for the three TCR chains contain numbers of γδ thymocytes comparable to those of mice transgenic for both TCRγ and TCRδ chains, and numbers of αβ thymocytes similar to those found in mice solely transgenic for a rearranged TCRβ chain gene. γδ T cells from the triple transgenic mice express the transgenic TCRβ chain, but do not express a TCRα chain, and, by a number of phenotypic and molecular parameters, appear to be bona fide γδ thymocytes. Our results reveal a remarkable degree of independence in the generation of αβ and γδ lineage cells from progenitor cells that, in theory, could simultaneously express a TCRγδ and a pre-TCR.
Transcriptional Regulation of the Human TLR9 Gene
Authors: Takeshita Fumihiko , Suzuki Koichi , Sasaki Shin , Ishii Norihisa , Klinman Dennis M. , Ishii Ken J.
Published: April 2014

To clarify the molecular basis of human TLR9 (hTLR9) gene expression, the activity of the hTLR9 gene promoter was characterized using the human myeloma cell line RPMI 8226. Reporter gene analysis and EMSA demonstrated that hTLR9 gene transcription was regulated via four cis-acting elements, cAMP response element, 5′-PU box, 3′-PU box, and a C/EBP site, that interacted with the CREB1, Ets2, Elf1, Elk1, and C/EBPα transcription factors. Other members of the C/EBP family, such as C/EBPβ, C/EBPδ, and C/EBPε, were also important for TLR9 gene transcription. CpG DNA-mediated suppression of TLR9 gene transcription led to decreased binding of the trans-acting factors to their corresponding cis-acting elements. It appeared that suppression was mediated via c-Jun and NF-κB p65 and that cooperation among CREB1, Ets2, Elf1, Elk1, and C/EBPα culminated in maximal transcription of the TLR9 gene. These findings will help to elucidate the mechanism of TLR9 gene regulation and to provide insight into the process by which TLR9 evolved in the mammalian immune system.
pH-Triggered Microparticles for Peptide Vaccination
Authors: Haining W. Nicholas , Anderson Daniel G. , Little Steven R. , von Berwelt-Baildon Michael S. , Cardoso Angelo A. , Alves Pedro , Kosmatopoulos Kostas , Nadler Lee M. , Langer Robert , Kohane Daniel S.
Published: April 2014

Improving vaccine delivery to human APCs is a way to increase the CTL response to vaccines. We report the use of a novel pH-triggered microparticle that exploits the ability of APCs to cross-present MHC I-restricted Ags that have been engulfed in the low pH environment of the phagosome. A model MHC class I-restricted peptide Ag from the influenza A matrix protein was encapsulated in spray-dried microparticles composed of dipalmitoylphosphatidylcholine and the pH-sensitive polymethacrylate Eudragit E100. Release of the peptide from the particle was triggered by a drop in pH to the acidity normally found in the phagosome. The particles were efficiently phagocytosed by human monocytes and dendritic cells with minimal cellular toxicity and no functional impairment. Encapsulation of the peptide in the microparticles resulted in efficient presentation of the peptide to CD8+ T cells by human dendritic cells in vitro, and was superior to unencapsulated peptide or peptide encapsulated in an analogous pH-insensitive particle. Vaccination of human HLA-A*0201 transgenic mice with peptide encapsulated in pH-triggering microparticles resulted in priming of CTL responses. These microparticles can be modified to coencapsulate a range of adjuvants along with the Ag of interest. Encapsulation of MHC I epitopes in pH-triggered microparticles increases Ag presentation and may improve CD8+ T cell priming to peptide vaccines against viruses and cancer.
Characterization of Bovine Homologues of Granulysin and NK-lysin
Authors: Endsley Janice J. , Furrer Jason L. , Endsley Mark A. , McIntosh Mark A. , Maue Alexander C. , Waters W. Ray , Lee David R. , Estes D. Mark
Published: April 2014

Granulysin and NK-lysin are antimicrobial proteins found in the granules of human and swine cytotoxic lymphocytes. A murine counterpart to granulysin has not been identified to date, indicating the importance of additional models to fully characterize the role of granulysin-like molecules in the immune response to infectious disease. Two partial nucleotide sequences corresponding to the complete functional domain of granulysin and NK-lysin were amplified from bovine PBMC mRNA. Following stimulation with phorbol ester and calcium ionophore, expression of the bovine gene was detected in CD3+ T cells, CD4+ T cells, CD8+ T cells, WC1+ γδ T cells, and PBMC depleted of CD3+ T cells, but was absent in CD21+ cells and CD14+ cells. Intracellular flow cytometry and immunoblotting confirmed the presence of protein corresponding to the bovine granulysin homologue in activated T lymphocytes and PBMC. Synthetic human, bovine, and swine peptides corresponding to the C terminus of helix 2 through helix 3 region of granulysin displayed potent antimicrobial activity against Escherichia coli, Salmonella enteritidis, Staphylococcus aureus, and Mycobacterium bovis bacillus Calmette-Guérin. Human and bovine peptides corresponding to helix 2 displayed antimycobacterial activity against M. bovis bacillus Calmette-Guérin. Expression of the bovine gene was detected in laser microscopy-dissected lymph node lesions from an M. bovis-infected animal. The identification of a biologically active bovine homologue to granulysin demonstrates the potential of the bovine model in characterizing the role of granulysin in the immune response to a variety of infectious agents.
Phospholipases D1 and D2 Coordinately Regulate Macrophage Phagocytosis
Authors: Iyer Shankar S. , Barton James A. , Bourgoin Sylvain , Kusner David J.
Published: April 2014

Phagocytosis is a fundamental feature of the innate immune system, required for antimicrobial defense, resolution of inflammation, and tissue remodeling. Furthermore, phagocytosis is coupled to a diverse range of cytotoxic effector mechanisms, including the respiratory burst, secretion of inflammatory mediators and Ag presentation. Phospholipase D (PLD) has been linked to the regulation of phagocytosis and subsequent effector responses, but the identity of the PLD isoform(s) involved and the molecular mechanisms of activation are unknown. We used primary human macrophages and human THP-1 promonocytes to characterize the role of PLD in phagocytosis. Macrophages, THP-1 cells, and other human myelomonocytic cells expressed both PLD1 and PLD2 proteins. Phagocytosis of complement-opsonized zymosan was associated with stimulation of the activity of both PLD1 and PLD2, as demonstrated by a novel immunoprecipitation-in vitro PLD assay. Transfection of dominant-negative PLD1 or PLD2 each inhibited the extent of phagocytosis (by 55–65%), and their combined effects were additive (reduction of 91%). PLD1 and PLD2 exhibited distinct localizations in resting macrophages and those undergoing phagocytosis, and only PLD1 localized to the phagosome membrane. The COS-7 monkey fibroblast cell line, which has been used as a heterologous system for the analysis of receptor-mediated phagocytosis, expressed PLD2 but not PLD1. These data support a model in which macrophage phagocytosis is coordinately regulated by both PLD1 and PLD2, with isoform-specific localization. Human myelomonocytic cell lines accurately model PLD-dependent signal transduction events required for phagocytosis, but the heterologous COS cell system does not.
Cloning and Characterization of Chicken IL-10 and Its Role in the Immune Response to Eimeria maxima
Authors: Rothwell Lisa , Young John R. , Zoorob Rima , Whittaker Catherine A. , Hesketh Pat , Archer Andrew , Smith Adrian L. , Kaiser Pete
Published: April 2014

We isolated the full-length chicken IL-10 (chIL-10) cDNA from an expressed sequence tag library derived from RNA from cecal tonsils of Eimeria tenella-infected chickens. It encodes a 178-aa polypeptide, with a predicted 162-aa mature peptide. Chicken IL-10 has 45 and 42% aa identity with human and murine IL-10, respectively. The structures of the chIL-10 gene and its promoter were determined by direct sequencing of a bacterial artificial chromosome containing chIL-10. The chIL-10 gene structure is similar to (five exons, four introns), but more compact than, that of its mammalian orthologues. The promoter is more similar to that of Fugu IL-10 than human IL-10. Chicken IL-10 mRNA expression was identified mainly in the bursa of Fabricius and cecal tonsils, with low levels of expression also seen in thymus, liver, and lung. Expression was also detected in PHA-activated thymocytes and LPS-stimulated monocyte-derived macrophages, with high expression in an LPS-stimulated macrophage cell line. Recombinant chIL-10 was produced and bioactivity demonstrated through IL-10-induced inhibition of IFN-γ synthesis by mitogen-activated lymphocytes. We measured the expression of mRNA for chIL-10 and other signature cytokines in gut and spleen of resistant (line C.B12) and susceptible (line 15I) chickens during the course of an E. maxima infection. Susceptible chickens showed higher levels of chIL-10 mRNA expression in the spleen, both constitutively and after infection, and in the small intestine after infection than did resistant chickens. These data indicate a potential role for chIL-10 in changing the Th bias during infection with an intracellular protozoan, thereby contributing to susceptibility of line 15I chickens.
Specific Modulation of Astrocyte Inflammation by Inhibition of Mixed Lineage Kinases with CEP-1347
Authors: Falsig Jeppe , Pörzgen Peter , Lotharius Julie , Leist Marcel
Published: April 2014

Inflammatory conversion of murine astrocytes correlates with the activation of various MAPK, and inhibition of terminal MAPKs like JNK or p38 dampens the inflammatory reaction. Mixed lineage kinases (MLKs), a family of MAPK kinase kinases, may therefore be involved in astrocyte inflammation. In this study, we explored the effect of the MLK inhibitors CEP-1347 and CEP-11004 on the activation of murine astrocytes by either TNF plus IL-1 or by a complete cytokine mix containing additional IFN-γ. The compounds blocked NO-, PG-, and IL-6 release with a median inhibitory concentration of ∼100 nM. This activity correlated with a block of the JNK and the p38 pathways activated in complete cytokine mix-treated astrocytes. Although CEP-1347 did not affect the activation of NF-κB, it blocked the expression of cyclooxygenase-2 and inducible NO synthase at the transcriptional level. Quantitative transcript profiling of 17 inflammation-linked genes revealed a specific modulation pattern of astrocyte activation by MLK inhibition, for instance, characterized by up-regulation of the anti-stress factors inhibitor of apoptosis protein-2 and activated transcription factor 4, no effect on manganese superoxide dismutase and caspase-11, and down-regulation of major inflammatory players like TNF, GM-CSF, urokinase-type plasminogen activator, and IL-6. In conclusion, MLK inhibitors like CEP-1347 are highly potent astrocyte immune modulators with a novel spectrum of activity.
Complete Complement Components C4A and C4B Deficiencies in Human Kidney Diseases and Systemic Lupus Erythematosus
Authors: Yang Yan , Lhotta Karl , Chung Erwin K. , Eder Paula , Neumair Friedrich , Yu C. Yung
Published: April 2014

Although a heterozygous deficiency of either complement component C4A or C4B is common, and each has a frequency of ∼20% in a Caucasian population, complete deficiencies of both C4A and C4B proteins are extremely rare. In this paper the clinical courses for seven complete C4 deficiency patients are described in detail, and the molecular defects for complete C4 deficiencies are elucidated. Three patients with homozygous HLA A24 Cw7 B38 DR13 had systemic lupus erythematosus, mesangial glomerulonephritis, and severe skin lesions or membranous nephropathy. Immunofixation, genomic restriction fragment length polymorphisms, and pulsed field gel electrophoresis experiments revealed the presence of monomodular RP-C4-CYP21-TNX (RCCX) modules, each containing a solitary, long C4A mutant gene. Sequencing of the mutant C4A genes revealed a 2-bp, GT deletion in exon 13 that leads to protein truncation. The other four patients with homozygous HLA A30 B18 DR7 had SLE, severe kidney disorders including mesangial or membranoproliferative glomerulonephritis, and/or Henoch Schoenlein purpura. Molecular genetic analyses revealed an unusual RCCX structure with two short C4B mutant genes, each followed by an intact gene for steroid 21-hydroxylase. Nine identical, intronic mutations were found in each mutant C4B. In particular, the 8127 g→a mutation present at the donor site of intron 28 may cause an RNA splice defect. Analyses of 12 complete C4 deficiency patients revealed two hot spots of deleterious mutations: one is located at exon 13, the others within a 2.6-kb genomic region spanning exons 20–29. Screening of these mutations may facilitate epidemiologic studies of C4 in infectious, autoimmune, and kidney diseases.
Characterization of Rat CD8+ Uveitogenic T Cells Specific for Interphotoreceptor Retinal-Binding Protein 1177–1191
Authors: Shao Hui , Sun Sheher L. , Kaplan Henry J. , Sun Deming
Published: April 2014

The uveitogenic T cells that mediate experimental autoimmune uveitis are commonly assumed to be exclusively CD4+. In the present study, we showed that, although a panel of long-term cultured rat uveitogenic T cell lines specific for the interphotoreceptor retinal-binding protein peptide, R16, all expressed CD4, ∼40% of the R16-specific uveitogenic T cells freshly prepared from Ag-immunized rats were CD8+αβTCR+, as demonstrated by CFSE staining. We showed that the expansion of these CD8+αβTCR+ T cells was Ag-specific and that highly purified CD8+ R16-specific T cells were able to induce uveitis on transfusion into naive rats. Moreover, CD8+ uveitogenic T cells more readily switched phenotype from, and to, TCR−CD8−CD4− during in vivo or in vitro activation compared with their CD4+ counterparts. In a previous study, we showed that highly purified CD8+ myelin oligodendrocyte glycoprotein-specific T cells induced more severe autoimmune encephalomyelitis than the corresponding CD4+ T cells. In this study, we show that an interphotoreceptor retinal-binding protein peptide consistently activated a high proportion of CD8+αβTCR+ T cells, which were uveitogenic in Lewis rats.
Cutting Edge: CD95 Maintains Effector T Cell Homeostasis in Chronic Immune Activation
Authors: Arens Ramon , Baars Paul A. , Jak Margot , Tesselaar Kiki , van der Valk Martin , van Oers Marinus H. J. , van Lier René A. W.
Published: April 2014

The elimination of activated T cells is important to maintain homeostasis and avoid immunopathology. CD95 (Fas/APO-1) has been identified as a death mediator for activated T cells in vitro but the function of CD95 in death of mature T cells in vivo is still controversial. Here we show that triggering of the costimulatory TNF receptor family member CD27 sensitized T cells for CD95-induced apoptosis. CD95-deficient (lpr/lpr) T cells massively expanded and differentiated into IFN-γ-secreting effector cells in transgenic mice that constitutively express the CD27 ligand, CD70. Concomitantly, CD95-deficient CD70 transgenic mice became moribund by 4 wk of age with severe liver pathology and bone marrow failure. These findings establish that CD95 is a critical regulator of effector T cell homeostasis in chronic immune activation.
TGF-β1 Inhibits Mast Cell FcεRI Expression
Authors: Gomez Gregorio , Ramirez Carlos D. , Rivera Juan , Patel Manish , Norozian Farnaz , Wright Harry V. , Kashyap Mohit V. , Barnstein Brian O. , Fischer-Stenger Krista , Schwartz Lawrence B. , Kepley Christopher L. , Ryan John J.
Published: April 2014

Mast cell activation through the high affinity IgE receptor (FcεRI) is a critical component of atopic inflammation. The cytokine TGF-β1 has been shown to inhibit IgE-dependent mast cell activation, possibly serving to dampen mast cell-mediated inflammatory responses. We present proof that TGF-β1 inhibits mast cell FcεRI expression through a reversible pathway that diminishes protein, but not mRNA, expression of the FcεRI subunit proteins α, β, and γ. The stability of the expressed proteins and the assembled cell surface complex was unaltered by TGF-β1 treatment. However, TGF-β1 decreased the rate of FcεRI β-chain synthesis, arguing that this inhibitory cytokine exerts its effects at the level of mRNA translation. TGF-β1 consistently diminished FcεRI expression on cultured human or mouse mast cells as well as freshly isolated peritoneal mast cells. The related cytokines, TGF-β2 and TGF-β3, had similar effects. We propose that TGF-β1 acts as a negative regulator of mast cell function, in part by decreasing FcεRI expression.
Estrogen Regulates CCR Gene Expression and Function in T Lymphocytes
Authors: Mo RuRan , Chen Jun , Grolleau-Julius Annabelle , Murphy Hedwig S. , Richardson Bruce C. , Yung Raymond L.
Published: April 2014

Estrogen has been implicated in the observed female bias in autoimmune diseases. However, the mechanisms behind this gender dimorphism are poorly defined. We have previously reported that in vivo T cell trafficking is gender- and estrogen-dependent. Chemokine receptors are critical determinants of T cell homing and immune response. In this study, we show that the female gender is associated with increased CD4+ T cell CCR1-CCR5 gene and protein expression in mice. The increased CCR expression correlates with enhanced in vitro chemotaxis response to MIP-1β (CCL4). In vivo treatment of young oophorectomized and postmenopausal female mice with 17β-estradiol also increased CD4+ T cell CCR expression. Finally, 17β-estradiol enhances tyrosine phosphorylation in T cells stimulated with MIP-1α in a time-dependent manner. Our results indicate an important role of estrogen in determining T cell chemokine response that may help explain the increased susceptibility and severity of autoimmune diseases in females.
Reactive Oxygen Species and 12/15-Lipoxygenase Contribute to the Antiproliferative Capacity of Alternatively Activated Myeloid Cells Elicited during Helminth Infection
Authors: Brys Lea , Beschin Alain , Raes Geert , Ghassabeh Gholamreza Hassanzadeh , Noël Wim , Brandt Jef , Brombacher Frank , Baetselier Patrick De
Published: April 2014

Understanding the role of CD11b+GR-1+ myeloid suppressor cells in the immune suppression and immunoregulation associated with a variety of diseases may provide therapeutic opportunities. In this article, we show, in a model of helminth infection, that CD11b+GR-1+ myeloid suppressor cells but not CD11b+F4/80high mature macrophages expanded in the peritoneal cavity of BALB/c mice implanted with Taenia crassiceps. Peritoneal cell populations from early stage-infected animals impaired T cell proliferation by secreting NO. Yet, they lost their ability to secrete NO in the late stage of infection. Concomitantly, their capacity to exert arginase activity and to express mRNAs coding for FIZZ1 (found in inflammatory zone 1), Ym, and macrophage galactose-type C-type lectin increased. Furthermore, cells from early stage-infected mice triggered T cells to secrete IFN-γ and IL-4, whereas in the late stage of infection, they only induced IL-4 production. These data suggest that CD11b+GR-1+ myeloid suppressor cells displaying an alternative activation phenotype emerged gradually as T. crassiceps infection progressed. Corroborating the alternative activation status in the late stage of infection, the suppressive activity relied on arginase activity, which facilitated the production of reactive oxygen species including H2O2 and superoxide. We also document that the suppressive activity of alternative myeloid suppressor cells depended on 12/15-lipoxygenase activation generating lipid mediators, which triggered peroxisome proliferator-activated receptor-γ. IL-4 and IL-13 signaling contributed to the expansion of myeloid suppressor cells in the peritoneal cavity of T. crassiceps-infected animals and to their antiproliferative activity by allowing arginase and 12/15-lipoxygenase gene expression.
Recombinant C345C and Factor I Modules of Complement Components C5 and C7 Inhibit C7 Incorporation into the Complement Membrane Attack Complex
Authors: Thai Chuong-Thu , Ogata Ronald T.
Published: April 2014

Complement component C5 binds to components C6 and C7 in reversible reactions that are distinct from the essentially nonreversible associations that form during assembly of the complement membrane attack complex (MAC). We previously reported that the ∼150-aa residue C345C domain (also known as NTR) of C5 mediates these reversible reactions, and that the corresponding recombinant module (rC5-C345C) binds directly to the tandem pair of ∼75-residue factor I modules from C7 (C7-FIMs). We suggested from these and other observations that binding of the C345C module of C5 to the FIMs of C7, but not C6, is also essential for MAC assembly itself. The present report describes a novel method for assembling a complex that appears to closely resemble the MAC on the sensor chip of a surface plasmon resonance instrument using the complement-reactive lysis mechanism. This method provides the ability to monitor individually the incorporation of C7, C8, and C9 into the complex. Using this method, we found that C7 binds to surface-bound C5b,6 with a Kd of ∼3 pM, and that micromolar concentrations of either rC5-C345C or rC7-FIMs inhibit this early step in MAC formation. We also found that similar concentrations of either module inhibited complement-mediated erythrocyte lysis by both the reactive lysis and classical pathway mechanisms. These results demonstrate that the interaction between the C345C domain of C5 and the FIMs of C7, which mediates reversible binding of C5 to C7 in solution, also plays an essential role in MAC formation and complement lytic activity.
Dendritic Cells Cross-Present Exogenous Fungal Antigens to Stimulate a Protective CD8 T Cell Response in Infection byHistoplasma capsulatum
Authors: Lin Jr-Shiuan , Yang Chiao-Wen , Wang Dah-Wei , Wu-Hsieh Betty A.
Published: April 2014

The contribution of CD8 T cells in host defense against histoplasmosis is minor in the CD4 T cell-intact mouse, as it has been shown that depleting CD8 T cells only marginally affects fungal clearance. However, it remains to be determined whether the CD8 T cells are protective in a host lacking functional CD4 T cells. In this study, MHC class II-deficient mice infected with Histoplasma capsulatum (Histoplasma) kept the fungus in check for up to 16 wk, indicating that CD8 T cells are able to limit fungal replication. Ex vivo studies showed that CD8 T cells from Histoplasma-infected mice expressed both intracytoplasmic IFN-γ and granzyme B. Furthermore, CD8 T cells exhibited cytotoxic activity against macrophage targets containing Histoplasma. We demonstrated that the macrophage, being the primary host cell as well as the effector cell, can also serve as Ag donor to dendritic cells. Histoplasma-specific CD8 T cells are stimulated by dendritic cells that present exogenous Histoplasma Ags, either through direct ingestion of yeasts or through uptake of apoptotic macrophage-associated fungal Ags, a process known as “cross-presentation.” Based on these results, we present a model detailing the possible sequence of events leading to a cell-mediated immune response and fungal clearance in Histoplasma-infected hosts.
Caspase-8 Activity Prevents Type 2 Cytokine Responses and Is Required for Protective T Cell-Mediated Immunity against Trypanosoma cruzi Infection
Authors: Silva Elisabeth M. , Guillermo Landi V. C. , Ribeiro-Gomes Flávia L. , De Meis Juliana , Pereira Renata M. S. , Wu Zhengqi , Calegari-Silva Teresa C. , Seabra Sérgio H. , Lopes Ulisses G. , Siegel Richard M. , DosReis George A. , Lopes Marcela F.
Published: April 2014

During Trypanosoma cruzi infection, T cells up-regulate caspase-8 activity. To assess the role of caspase-8 in T cell-mediated immunity, we investigated the effects of caspase-8 inhibition on T cells in viral FLIP (v-FLIP) transgenic mice. Compared with wild-type controls, increased parasitemia was observed in v-FLIP mice infected with T. cruzi. There was a profound decrease in expansion of both CD4 and CD8 T cell subsets in the spleens of infected v-FLIP mice. We did not find differences in activation ratios of T cells from transgenic or wild-type infected mice. However, the numbers of memory/activated CD4 and CD8 T cells were markedly reduced in v-FLIP mice, possibly due to defective survival. We also found decreased production of IL-2 and increased secretion of type 2 cytokines, IL-4 and IL-10, which could enhance susceptibility to infection. Similar, but less pronounced, alterations were observed in mice treated with the caspase-8 inhibitor, zIETD. Furthermore, blockade of caspase-8 by zIETD in vitro mimicked the effects observed on T. cruzi infection in vivo, affecting the generation of activated/memory T cells and T cell cytokine production. Caspase-8 is also required for NF-κB signaling upon T cell activation. Blockade of caspase-8 by either v-FLIP expression or treatment with zIETD peptide decreased NF-κB responses to TCR:CD3 engagement in T cell cultures. These results suggest a critical role for caspase-8 in the establishment of T cell memory, cell signaling, and regulation of cytokine responses during protozoan infection.