bluuebunny/crossref_metadata_2025 huggingface dataset:
In Vivo Enhancement of Peptide Display by MHC Class II Molecules with Small Molecule Catalysts of Peptide Exchange
Authors: Call Melissa J. , Xing Xuechao , Cuny Gregory D. , Seth Nilufer P. , Altmann Daniel M. , Fugger Lars , Krogsgaard Michelle , Stein Ross L. , Wucherpfennig Kai W.
Published: May 2009

Rapid binding of peptides to MHC class II molecules is normally limited to a deep endosomal compartment where the coordinate action of low pH and HLA-DM displaces the invariant chain remnant CLIP or other peptides from the binding site. Exogenously added peptides are subject to proteolytic degradation for extended periods of time before they reach the relevant endosomal compartment, which limits the efficacy of peptide-based vaccines and therapeutics. In this study, we describe a family of small molecules that substantially accelerate the rate of peptide binding to HLA-DR molecules in the absence of HLA-DM. A structure-activity relationship study resulted in analogs with significantly higher potency and also defined key structural features required for activity. These compounds are active over a broad pH range and thus enable efficient peptide loading at the cell surface. The small molecules not only enhance peptide presentation by APC in vitro, but are also active in vivo where they substantially increase the fraction of APC on which displayed peptide is detectable. We propose that the small molecule quickly reaches draining lymph nodes along with the coadministered peptide and induces rapid loading of peptide before it is destroyed by proteases. Such compounds may be useful for enhancing the efficacy of peptide-based vaccines and other therapeutics that require binding to MHC class II molecules.
Autoreactive Anti-DNA Transgenic B Cells in Lupus-Prone New Zealand Black/New Zealand White Mice Show Near Perfect L Chain Allelic Exclusion
Authors: Makdasi Efi , Fischel Ruth , Kat Inbal , Eilat Dan
Published: May 2009

Recent work on B cell tolerance and autoimmunity has suggested the L chain allelic inclusion is a property of autoreactive B cells and is closely linked to receptor editing. Allelic inclusion could rescue autoreactive B cells from clonal deletion by reducing their effective BCR surface density. We have investigated this phenomenon in anti-DNA producing hybridomas, derived from different strains of Ig gene-targeted, lupus-prone NZB/NZW mice. Our results indicate that isotype and allelic exclusion was strictly maintained in most high- and low-affinity, edited and nonedited, anti-DNA transgenic B cells. However, a substantial fraction of the anti-DNA hybridomas expressed a very restricted set of nonproductively rearranged L chain mRNA, in addition to the productive anti-DNA L chain. The aberrant L chains could have a role in the selection and survival of autoreactive B cells in these autoimmune mice.
Regulatory T Cell Suppression Is Potentiated by Target T Cells in a Cell Contact, IL-35- and IL-10-Dependent Manner
Authors: Collison Lauren W. , Pillai Meenu R. , Chaturvedi Vandana , Vignali Dario A. A.
Published: May 2009

Regulatory T cells (Treg) are believed to suppress conventional T cell (Tconv) proliferation in vitro in a contact-dependent, cytokine-independent manner, based in part on experiments in which Treg and Tconv are separated by a permeable membrane. We show that the production of IL-35, a novel inhibitory cytokine expressed by natural Treg, increases substantially following contact with Tconv. Surprisingly, Treg were able to mediate potent suppression of Tconv across a permeable membrane when placed in direct contact with Tconv in the upper chamber of a Transwell plate. Suppression was IL-35 and IL-10 dependent, and Tconv activation was required for maximal potentiation of Treg suppression. These data suggest that it is the induction of suppression, rather than the function of Treg that is obligatorily contact dependent.
Vaccines Containing de-N-Acetyl Sialic Acid Elicit Antibodies Protective against Neisseria meningitidis Groups B and C
Authors: Moe Gregory R. , Bhandari Tamara S. , Flitter Becca A.
Published: May 2009

Murine mAbs that were produced by immunization with a vaccine containing the N-propionyl derivative of Neisseria meningitidis group B (MenB) capsular polysaccharide (NPr MBPS) mediate protective responses against MenB but were not reactive with unmodified MBPS or chemically identical human polysialic acid (PSA). Recently, we showed that some of the mAbs were reactive with MBPS derivatives that contain de-N-acetyl sialic acid residues. In this study we evaluated the immunogenicity of de-N-acetyl sialic acid-containing derivatives of PSA (de-N-acetyl PSA) in mice. Four de-N-acetyl PSA Ags were prepared and conjugated to tetanus toxoid, including completely de-N-acetylated PSA. All of the vaccines elicited anti-de-N-acetyl PSA responses (titers ≥1/10,000), but only vaccines enriched for nonreducing end de-N-acetyl residues by treatment with exoneuraminidase or complete de-N-acetylation elicited high titers against the homologous Ag. Also, nonreducing end de-N-acetyl residue-enriched vaccines elicited IgM and IgG Abs of all subclasses that could bind to MenB. The results suggest that the zwitterionic characteristic of neuraminic acid, particularly at the nonreducing end, may be important for processing and presentation mechanisms that stimulate T cells. Abs elicited by all four vaccines were able to activate deposition of human complement proteins and passively protect against challenge by MenB in the infant rat model of meningococcal bacteremia. Some vaccine antisera mediated bactericidal activity against a N. meningitidis group C strain with human complement. Thus, de-N-acetyl PSA Ags are immunogenic and elicit Abs that can be protective against MenB and N. meningitidis group C strains.
The Adaptor Molecule MyD88 Directly Promotes CD8 T Cell Responses to Vaccinia Virus
Authors: Zhao Yuan , De Trez Carl , Flynn Rachel , Ware Carl F. , Croft Michael , Salek-Ardakani Shahram
Published: May 2009

Vaccinia virus (VACV) elicits a robust CD8 T cell response that plays an important role in host resistance. To date, there is little information on the molecules that are essential to generate large pools of VACV-specific effector CD8 T cells. In this study, we show that the adaptor molecule MyD88 is critical for the magnitude of primary CD8 T cell responses to both dominant and subdominant VACV epitopes. MyD88−/− mice exhibit profound reduction in CD8 T cell expansion and antiviral cytokine production. Surprisingly, the defect was not due to impaired APC function, as MyD88−/− dendritic cells matured normally and were able to promote strong CD8 T cell priming following VACV infection. Rather, adoptive transfer experiments demonstrated that intrinsic MyD88-dependent pathways in CD8 T cells were critical. MyD88-deficient CD8 T cells failed to accumulate in wild-type hosts and poor expansion of MyD88-deficient VACV-specific CD8 T cells resulted after virus infection. In contrast, no defect was evident in the absence of TRIF, TLR2, TLR4, TLR9, and IL-1R. Together, our results highlight an important role for MyD88 in initial antiviral CD8 T cell responses and suggest that targeting this pathway may be useful in promoting and sustaining anti-VACV immunity.
PD-1 and CTLA-4 Inhibitory Cosignaling Pathways in HIV Infection and the Potential for Therapeutic Intervention
Authors: Kaufmann Daniel E. , Walker Bruce D.
Published: May 2009

The balance between proinflammatory mechanisms and the dampening of excessive immune activation is critical for successful clearance of a pathogen without harm to the host. In particular, molecules of the B7:CD28 family play a critical role in regulating T cell activation and peripheral tolerance. Chronic pathogens like HIV, which is characterized by ongoing viral replication despite detectable virus-specific T cell responses, and cancer cells have exploited these pathways to attenuate Ag-specific T cell immunity. This review summarizes evidence that molecules of the B7:CD28 family, PD-1, CTLA-4, and their ligands, play an active and reversible role in virus-specific T cell exhaustion associated with HIV infection in humans and in the SIV model in macaques. We discuss the potential for immunotherapeutic interventions based on manipulation of these inhibitory networks, the promising data obtained with blockade of the PD-1 pathway in animal models, and the challenges to such therapies.
Activation of Melanoma Differentiation-Associated Gene 5 Causes Rapid Involution of the Thymus
Authors: Anz David , Thaler Raffael , Stephan Nicolas , Waibler Zoe , Trauscheid Michael J. , Scholz Christoph , Kalinke Ulrich , Barchet Winfried , Endres Stefan , Bourquin Carole
Published: May 2009

In the course of infection, the detection of pathogen-associated molecular patterns by specialized pattern recognition receptors in the host leads to activation of the innate immune system. Whereas the subsequent induction of adaptive immune responses in secondary lymphoid organs is well described, little is known about the effects of pathogen-associated molecular pattern-induced activation on primary lymphoid organs. Here we show that activation of innate immunity through the virus-sensing melanoma differentiation-associated gene 5 (MDA-5) receptor causes a rapid involution of the thymus. We observed a strong decrease in thymic cellularity associated with characteristic alterations in thymic subpopulations and microanatomy. In contrast, immune stimulation with potent TLR agonists did not lead to thymic involution or induce changes in thymic subpopulations, demonstrating that thymic pathology is not a general consequence of innate immune activation. We determined that suppression of thymocyte proliferation and enhanced apoptosis are the essential cellular mechanisms involved in the decrease in thymic size upon MDA-5 activation. Further, thymic involution critically depended on type I IFN. Strikingly however, no direct action of type I IFN on thymocytes was required, given that the decrease in thymic size was still observed in mice with a selective deletion of the type I IFN receptor on T cells. All changes observed were self-limiting, given that cessation of MDA-5 activation led to a rapid recovery of thymic size. We show for the first time that the in vivo activation of the virus-sensing MDA-5 receptor leads to a rapid and reversible involution of the thymus.
Effector/Memory but Not Naive Regulatory T Cells Are Responsible for the Loss of Concomitant Tumor Immunity
Authors: Lin Yung-Chang , Chang Li-Yuan , Huang Ching-Tai , Peng Hui-Min , Dutta Avijit , Chen Tse-Ching , Yeh Chau-Ting , Lin Chun-Yen
Published: May 2009

The phenomenon of concomitant tumor immunity involves a tumor-bearing host rejecting another similar tumor at a distant site and suggests the existence of tumor-specific immunity. Loss of this immunity may contribute to tumor metastasis. However, mechanisms underlying the loss of concomitant immunity are largely unknown. We set up a concomitant tumor immunity model in which this immunity is gradually lost as the primary tumor progresses. We found that CD8+ T cells, especially tumor-infiltrating CD8+ T cells, from mice that lost concomitant tumor immunity, possessed potent antitumor properties and strongly expressed effector molecules. Furthermore, effector/memory regulatory T cells (Treg cells, CD103+CD4+Foxp3+ T cells) increased as the primary tumor progressed. They initially accumulated around the tumor and in the spleen at later points. Not only did these cells more greatly express killing molecules, they also suppressed the functions of tumor-bearing CD8+ T cells in vitro and in vivo. Finally, we show that these effector/memory Treg cells inhibit concomitant tumor immunity in vivo. Taken together, data suggest that effector/memory Treg cells are responsible for the loss of concomitant tumor immunity associated with tumor progression.
Involvement of Glycoreceptors in Galactoxylomannan-Induced T Cell Death
Authors: Pericolini Eva , Gabrielli Elena , Cenci Elio , De Jesus Magdia , Bistoni Francesco , Casadevall Arturo , Vecchiarelli Anna
Published: May 2009

The major virulence factor of Cryptococcus neoformans is its capsular polysaccharide, which is also released into tissues. The shed polysaccharide is composed of glucuronoxylomannan, galactoxylomannan (GalXM), and mannoproteins. In a previous study, we demonstrated a direct interaction of purified soluble GalXM with T cells that induced their apoptosis. In this study, we focus on the mechanisms involved in the apoptotic effect of GalXM. In our experimental system, we analyzed the effect of GalXM on purified human T cells and Jurkat cells, a T cell line routinely used for apoptotic studies. Our results reveal that GalXM activates the extrinsic and intrinsic apoptotic pathways through the cleavage and recruitment of caspase-8. Caspase-8 elicits the downstream executioner caspase-3, caspase-6, and caspase-7 both directly and indirectly, via Bid cleavage and caspase-9 activation. These effects appeared to be primarily mediated by the interaction of GalXM with the glycoreceptors, which differed in human T and Jurkat cells. CD45 was primarily involved in Jurkat cells apoptosis while CD7 and CD43 mediated human T cell apoptosis. Our results highlight a new mechanism by which a microbial product can contribute to virulence through direct interaction with T cell glycoreceptors, thereby triggering lymphocyte apoptosis.
Tumor-Educated CD11bhighIalow Regulatory Dendritic Cells Suppress T Cell Response through Arginase I
Authors: Liu Qiuyan , Zhang Chaoxiong , Sun Anna , Zheng Yuanyuan , Wang Li , Cao Xuetao
Published: May 2009

Tumors can induce generation and accumulation of the immunosuppressive cells such as regulatory T cells in the tumor microenvironment, contributing to tumor escape from immunological attack. Although dendritic cell (DC)-based cancer vaccine can initiate antitumor immune response, regulatory DC subsets involved in the tolerance induction attracted much attention recently. Our previous studies demonstrate that the stromal microenvironment of the spleen, lung, and liver can program generation of CD11clowCD11bhighIalow DCs with regulatory function (CD11bhighIalow regulatory DCs). However, whether and how the tumor microenvironment can program generation of CD11bhighIalow regulatory DCs remain to be investigated. In this study, we used the freshly isolated tumor cells to mimic tumor microenvironment to coculture DCs and found that the freshly isolated tumor cells could drive DCs to differentiate into regulatory DCs with a CD11clowCD11bhighIalow phenotype and high expression of IL-10, NO, vascular endothelial growth factor, and arginase I. Tumor-educated CD11bhighIalow regulatory DCs inhibited CD4+ T cell proliferation both in vitro and in vivo. 3LL lung cancer-derived TGF-β and PGE2 were responsible for the generation of regulatory DCs. PGE2 was the main inducer of arginase I in regulatory DCs. Arginase I played a major role in the suppression of T cell response by regulatory DCs induced by 3LL lung cancer. A natural counterpart of CD11bhighIalow DCs was identified in tumor tissue, and CD11bhighIalow DCs sorted from 3LL lung cancer tissue expressed arginase I and inhibited T cell response. Therefore, tumors can educate DCs to differentiate into a regulatory DC subset, which contributes to constitution of the immunosuppressive tumor microenvironment and promotes tumor immune escape.
IL-1R Type I-Dependent Hemopoietic Stem Cell Proliferation Is Necessary for Inflammatory Granulopoiesis and Reactive Neutrophilia
Authors: Ueda Yoshihiro , Cain Derek W. , Kuraoka Masayuki , Kondo Motonari , Kelsoe Garnett
Published: May 2009

Infections and inflammation trigger neutrophilias that are supported by a hematopoietic program of accelerated granulopoiesis known as emergency granulopoiesis. The intrinsic factors that drive reactive neutrophilias and emergency granulopoiesis have been inferred but not demonstrated. Here, we show that alum cannot elicit reactive neutrophilias in IL-1R type I (IL-1RI)−/− mice, whereas other inflammatory responses, including eosinophilia and Ab production, remain intact. Analysis of this specific impairment revealed an unanticipated role for IL-1RI in supporting increased proliferation by granulocyte/macrophage progenitors and, surprisingly, multipotent progenitors and hematopoietic stem cells (HSC). Indeed, HSC and multipotent progenitor proliferative responses were most suppressed in IL-1RI−/− mice, suggesting a critical role for their proliferation in inflammatory granulopoiesis. Whereas IL-1 drives increased HSC proliferation directly in vitro, IL-1RI expression by radiation-resistant host cells was both necessary and sufficient for alum-induced HSC, multipotent progenitor, and granulocyte/macrophage progenitor proliferation and reactive neutrophilias in radiation chimeric mice. Thus, IL-1 plays a necessary, but indirect, role in the support of alum-induced neutrophilias by expanding both pluripotent and myeloid progenitor compartments to accelerate granulopoiesis.
Mesenchymal Stromal Cells Ameliorate Experimental Autoimmune Encephalomyelitis by Inhibiting CD4 Th17 T Cells in a CC Chemokine Ligand 2-Dependent Manner
Authors: Rafei Moutih , Campeau Philippe M. , Aguilar-Mahecha Adriana , Buchanan Marguerite , Williams Patrick , Birman Elena , Yuan Shala , Young Yoon Kow , Boivin Marie-Noëlle , Forner Kathy , Basik Mark , Galipeau Jacques
Published: May 2009

The administration of ex vivo culture-expanded mesenchymal stromal cells (MSCs) has been shown to reverse symptomatic neuroinflammation observed in experimental autoimmune encephalomyelitis (EAE). The mechanism by which this therapeutic effect occurs remains unknown. In an effort to decipher MSC mode of action, we found that MSC conditioned medium inhibits EAE-derived CD4 T cell activation by suppressing STAT3 phosphorylation via MSC-derived CCL2. Further analysis demonstrates that the effect is dependent on MSC-driven matrix metalloproteinase proteolytic processing of CCL2 to an antagonistic derivative. We also show that antagonistic CCL2 suppresses phosphorylation of AKT and leads to a reciprocal increased phosphorylation of ERK associated with an up-regulation of B7.H1 in CD4 T cells derived from EAE mice. CD4 T cell infiltration of the spinal cord of MSC-treated group was robustly decreased along with reduced plasma levels of IL-17 and TNF-α levels and in vitro from restimulated splenocytes. The key role of MSC-derived CCL2 was confirmed by the observed loss of function of CCL2−/− MSCs in EAE mice. In summary, this is the first report of MSCs modulating EAE biology via the paracrine conversion of CCL2 from agonist to antagonist of CD4 Th17 cell function.
Adeno-Associated Virus Capsid Structure Drives CD4-Dependent CD8+ T Cell Response to Vector Encoded Proteins
Authors: Mays Lauren E. , Vandenberghe Luk H. , Xiao Ru , Bell Peter , Nam Hyun-Joo , Agbandje-McKenna Mavis , Wilson James M.
Published: May 2009

The immunological sequelae of adeno-associated virus (AAV)-mediated gene transfer in vivo is quite complex. In murine models, most AAV capsids are associated with minimal or dysfunctional T cell responses to antigenic transgene products. In this study we compared T cell activation against AAV2/8 and AAV2/rh32.33 vectors expressing nuclear-targeted LacZ (nLacZ), GFP, or firefly luciferase in murine skeletal muscle. We show that, unlike AAV8, AAVrh32.33 yields qualitatively and quantitatively robust T cell responses to both the capsid and transgene product. AAV2/rh32.33.CB.nLacZ, but not AAV2/8, drives a high degree of cellular infiltration and a loss of detectable transgene expression in C57BL/6 mice. However, cellular immunity to AAVrh32.33 is ablated in the absence of CD4, CD40L, or CD28, permitting stable β-galactosidase expression. Treatment of CD40L−/− mice with the CD40 agonist, FGK45, failed to restore the CD8 response to AAV2/rh32.33.nLacZ, suggesting that additional factors are involved. Our results suggest that specific domains within the AAVrh32.33 capsid augment the adaptive response to both capsid and transgene Ags in a CD4-dependent pathway involving CD40L signaling and CD28 costimulation. Structural comparison of the AAV8 and rh32.33 capsids has identified key differences that may drive differential immunity by affecting tropism, Ag presentation or the activation of innate immunity. This murine model of AAV-mediated cytotoxicity allows us to delineate the mechanism of viral immune activation, which is relevant to the translation of AAV technology in higher order species.
Naive CD4 T Cell Proliferation Is Controlled by Mammalian Target of Rapamycin Regulation of GRAIL Expression
Authors: Lin Jack T. , Lineberry Neil B. , Kattah Michael G. , Su Leon L. , Utz Paul J. , Fathman C. Garrison , Wu Linda
Published: May 2009

In this study, we demonstrate that the E3 ubiquitin ligase gene related to anergy in lymphocytes (GRAIL) is expressed in quiescent naive mouse and human CD4 T cells and has a functional role in inhibiting naive T cell proliferation. Following TCR engagement, CD28 costimulation results in the expression of IL-2 whose signaling through its receptor activates the Akt-mammalian target of rapamycin (mTOR) pathway. Activation of mTOR allows selective mRNA translation, including the epistatic regulator of GRAIL, Otubain-1 (Otub1), whose expression results in the degradation of GRAIL and allows T cell proliferation. The activation of mTOR appears to be the critical component of IL-2R signaling regulating GRAIL expression. CTLA4-Ig treatment blocks CD28 costimulation and resultant IL-2 expression, whereas rapamycin and anti-IL-2 treatment block mTOR activation downstream of IL-2R signaling. Thus, all three of these biotherapeutics inhibit mTOR-dependent translation of mRNA transcripts, resulting in blockade of Otub1 expression, maintenance of GRAIL, and inhibition of CD4 T cell proliferation. These observations provide a mechanistic pathway sequentially linking CD28 costimulation, IL-2R signaling, and mTOR activation as important requirements for naive CD4 T cell proliferation through the regulation of Otub1 and GRAIL expression. Our findings also extend the role of GRAIL beyond anergy induction and maintenance, suggesting that endogenous GRAIL regulates general cell cycle and proliferation of primary naive CD4 T cells.
Expansion of Antigen-Specific Regulatory T Cells with the Topical Vitamin D Analog Calcipotriol
Authors: Ghoreishi Mehran , Bach Paxton , Obst Jennifer , Komba Mitsuhiro , Fleet James C. , Dutz Jan P.
Published: May 2009

1,25-Dihydroxyvitamin D3 is immunosuppressive both in vivo and in vitro. Topical vitamin D analogs such as calcipotriol alter keratinocyte function, but their effects on cutaneous immune responses are less well understood. We demonstrate that exposure of the skin to calcipotriol before transcutaneous immunization with OVA protein and CpG adjuvant prevents Ag-specific CD8+ T cell priming coincident with Langerhans cell depletion in the skin. Immunization through calcipotriol-treated skin induces CD4+CD25+ regulatory T cells (Treg) that prevent subsequent Ag-specific CD8+ T cell proliferation and IFN-γ production. Treg induced by calcipotriol are able to inhibit the induction and the elicitation of protein contact hypersensitivity. Topical calcipotriol treatment also induces RANKL (receptor activator of NF-κB ligand) expression by keratinocytes, a TNF family member involved in modulation of skin dendritic cells. UV light B induces Ag-specific tolerance when it is applied before transcutaneous immunization. We suggest that UV light B-induced tolerance is induced via a vitamin D receptor-dependent mechanism as vitamin D receptor (VDR) knockout mice fail to increase FoxP3+ Treg in their peripheral draining lymph node following irradiation. Additionally, keratinocytes of VDR−/− mice fail to induce RANKL upon UV irradiation or calcipotriol treatment. The in vivo expansion of Ag-specific Treg with the topical application of the vitamin D analog calcipotriol followed by transcutaneous immunization is a simple method to augment functional Ag-specific CD4+CD25+Foxp3+ Treg populations and mimics Ag-specific UV-induced tolerance.
A Network Modeling Approach to Analysis of the Th2 Memory Responses Underlying Human Atopic Disease
Authors: Bosco Anthony , McKenna Kathy L. , Firth Martin J. , Sly Peter D. , Holt Patrick G.
Published: May 2009

Complex cellular functions within immunoinflammatory cascades are conducted by networks of interacting genes. In this study, we employed a network modeling approach to dissect and interpret global gene expression patterns in allergen-induced Th cell responses that underpin human atopic disease. We demonstrate that a subnet of interconnected genes enriched for Th2 and regulatory T cell-associated signatures plus many novel genes is hardwired into the atopic response and is a hallmark of atopy at the systems level. We show that activation of this subnet is stabilized via hyperconnected “hub” genes, the selective disruption of which can collapse the entire network in a comprehensive fashion. Finally, we investigated gene expression in different Th cell subsets and show that regulatory T cell- and Th2-associated signatures partition at different stages of Th memory cell differentiation. Moreover, we demonstrate the parallel presence of a core element of the Th2-associated gene signature in bystander naive cells, which can be reproduced by rIL-4. These findings indicate that network analysis provides significant additional insight into atopic mechanisms beyond that achievable with conventional microarray analyses, predicting functional interactions between novel genes and previously recognized members of the allergic cascade. This approach provides novel opportunities for design of therapeutic strategies that target entire networks of genes rather than individual effector molecules.
Antigen-Specific Blockade of Lethal CD8 T-Cell Mediated Autoimmunity in a Mouse Model of Multiple Sclerosis
Authors: Na Shin-Young , Eujen Heike , Göbel Kerstin , Meuth Sven G. , Martens Kati , Wiendl Heinz , Hünig Thomas
Published: May 2009

Increasing evidence implies CD8 T cells in tissue-specific autoimmune diseases including multiple sclerosis. mAbs specific for MHC class I molecules presenting a dominant autoantigenic peptide may allow selective immunotherapy in such settings. We demonstrate the prophylactic and therapeutic efficacy of such a mAb in a transgenic mouse model of lethal demyelinating disease in which a neo-self Ag expressed by oligodendrocytes is targeted by CD8 T cells with transgenic Ag receptors. Mechanistic studies performed in vitro and in vivo indicate that it is the low expression of MHC class I on oligodendrocytes, which makes this form of Ag-specific intervention possible.
Killer Ig-Like Receptor (KIR) Genotype Predicts the Capacity of Human KIR-Positive CD56dim NK Cells to Respond to Pathogen-Associated Signals
Authors: Korbel Daniel S. , Norman Paul J. , Newman Kirsty C. , Horowitz Amir , Gendzekhadze Ketevan , Parham Peter , Riley Eleanor M.
Published: May 2009

IFN-γ emanating from NK cells is an important component of innate defense against infection. In this study, we demonstrate that, following in vitro stimulation of human peripheral blood NK cells with a variety of microbial ligands, CD56dim as well as CD56bright NK cells contribute to the overall NK cell IFN-γ response with, for most cell donors, IFN-γ+ CD56dim NK cells outnumbering IFN-γ+ CD56bright NK cells. We also observe that the magnitude of the human NK IFN-γ response to microbial ligands varies between individuals; that the antimicrobial response of CD56bright, but not CD56dim, NK cells is highly correlated with that of myeloid accessory cells; and that the ratio of IFN-γ+ CD56dim to IFN-γ+ CD56bright NK cells following microbial stimulation differs between individuals but remains constant for a given donor over time. Furthermore, ratios of IFN-γ+ CD56dim to IFN-γ+ CD56bright NK cells for different microbial stimuli are highly correlated and the relative response of CD56dim and CD56bright NK cells is highly significantly associated with killer Ig-like receptor (KIR) genotype. These data reveal an influence of KIR genotype, possibly mediated via NK cell education, on the ability of NK cells to respond to nonviral infections and have implications for genetic regulation of susceptibility to infection in humans.
Proinflammatory Adjuvants Enhance the Cognate Helper Activity of Aged CD4 T Cells
Authors: Maue Alexander C. , Eaton Sheri M. , Lanthier Paula A. , Sweet Kathryn B. , Blumerman Seth L. , Haynes Laura
Published: May 2009

Age-related declines in humoral responses contribute to the reduced efficacy of vaccines in older populations. Using an adoptive transfer model, we have shown that age-related intrinsic declines in CD4 T cell function contribute significantly to the reduced humoral responses observed with aging, resulting in reduced B cell expansion and differentiation as well as reduced IgG production. In this current study, we show that the helper function of aged CD4 T cells can be enhanced using a TLR-binding adjuvant or an adjuvant containing proinflammatory (PI) cytokines. The helper function of aged CD4 T cells was also enhanced when PI cytokines were added during in vitro CD4 effector generation. Enhanced helper activity resulted in improved expansion and differentiation of B cells and affinity maturation of IgG. PI cytokines also induced significant production of effector cytokines, including IL-4, IFN-γ, IL-17, and IL-21, by both young and aged CD4 T cells. Importantly, we also show that proinflammatory adjuvants can significantly enhance the humoral response in intact aged animals. We propose that one of the mechanisms involved in the ability of adjuvants to enhance both young and aged T cell responses includes driving multifaceted T cell differentiation and production of multiple cytokines by responding CD4 T cells.
Protein Kinase D1 Is Essential for MyD88-Dependent TLR Signaling Pathway
Authors: Park Jeoung-Eun , Kim Young-In , Yi Ae-Kyung
Published: May 2009

Protein kinase D1 (PKD1) has been shown to be involved in certain MAPK activation and cytokine expression by several TLR ligands. However, the precise physiological role of PKD1 in individual signaling from TLRs has not been fully addressed. In this study, we provide evidence that PKD1 is being activated by TLR ligands, except the TLR3 ligand. PKD1 activation by TLR ligands is dependent on MyD88, IL-1R-associated kinase 4 and 1, but independent of TNF-α receptor-associated factor 6. PKD1-knockdown macrophages and bone marrow-derived dendritic cells revealed that PKD1 is indispensable for the MyD88-dependent ubiquitination of TNF-α receptor-associated factor 6; activation of TGF-β-activated kinase 1, MAPKs, and transcription factors; and expression of proinflammatory genes induced by TLR ligands, but is not involved in expression of type I IFNs induced by TLR ligands and TRIF-dependent genes induced by TLR3 and TLR4 ligands. These results demonstrate that PKD1 is essential for MyD88-dependent proinflammatory immune responses.
Sialoadhesin-Positive Macrophages Bind Regulatory T Cells, Negatively Controlling Their Expansion and Autoimmune Disease Progression
Authors: Wu Chuan , Rauch Uwe , Korpos Eva , Song Jian , Loser Karin , Crocker Paul R. , Sorokin Lydia M.
Published: May 2009

An important regulatory suppressive function in autoimmune and other inflammatory processes has been ascribed to CD4+Foxp3+ regulatory T cells (Tregs), which requires direct cell-cell communication between Tregs, effector T cells, and APCs. However, the molecular basis for these interactions has not yet been clarified. We show here that sialoadhesin (Sn), the prototype of the siglec family of sialic acid-binding transmembrane proteins, expressed by resident and activated tissue-infiltrating macrophages, directly binds to Tregs, negatively regulating their expansion in an animal model of multiple sclerosis (MS), experimental autoimmune encephalomyelitis (EAE). In this model, macrophages infiltrate the CNS exhibiting tissue-destructing and demyelinating activity, leading to MS-like symptoms. We show here that severity of EAE symptoms is reduced in Sn knockout (KO) mice compared with wild-type littermates due to an up-regulation of CD4+Foxp3+ Treg lymphocytes. Through the use of a Sn fusion protein, Tregs were shown to express substantial amounts of Sn ligand on their cell surface, and direct interaction of Sn+ macrophages with Tregs specifically inhibited Treg but not effector T lymphocyte proliferation. Conversely, blocking of Sn on macrophages by Sn-specific Abs resulted in elevated proliferation of Tregs. Data indicate that Sn+ macrophages regulate Treg homeostasis which subsequently influences EAE progression. We propose a new direct cell-cell interaction-based mechanism regulating the expansion of the Tregs during the immune response, representing a “dialogue” between Sn+ macrophages and Sn-accessible sialic acid residues on Treg lymphocytes.
Dynamic Imaging of T Cell-Parasite Interactions in the Brains of Mice Chronically Infected withToxoplasma gondii
Authors: Schaeffer Marie , Han Seong-Ji , Chtanova Tatyana , van Dooren Giel G. , Herzmark Paul , Chen Ying , Roysam Badrinath , Striepen Boris , Robey Ellen A.
Published: May 2009

The intracellular parasite Toxoplasma gondii can establish persistent infection in the brain of a mammalian host, a standoff that involves the active participation of host CD8 T cells to control infection. CD8 T cells generally protect against intracellular pathogens by local delivery of effector molecules upon recognition of specific pathogen Ags on invaded host cells. However, the interactions between CD8 T cells, T. gondii, and APCs in the brain have not yet been examined. In this study we have used a mouse infection model in conjunction with two-photon microscopy of living brain tissue and confocal microscopy of fixed brain sections to examine the interactions between CD8 T cells, parasites, and APCs from chronically infected mice. We found that Ag-specific CD8 T cells were recruited to the brains of infected mice and persisted there in the presence of ongoing Ag recognition. Cerebral CD8 T cells made transient contacts with granuloma-like structures containing parasites and with individual CD11b+ APCs, including some that did not contain parasites. In contrast, T cells ignored intact Ag-bearing cysts and did not contact astrocytes or neurons, including neurons containing parasites or cysts. Our data represent the first direct observation of the dynamics of T cell-parasite interactions within living tissue and provide a new perspective for understanding immune responses to persistent pathogens in the brain.
Lentivector Immunization Stimulates Potent CD8 T Cell Responses against Melanoma Self-Antigen Tyrosinase-Related Protein 1 and Generates Antitumor Immunity in Mice
Authors: Liu Yanjun , Peng Yibing , Mi Michael , Guevara-Patino Jose , Munn David H. , Fu Ning , He Yukai
Published: May 2009

Recombinant lentivector immunization has been demonstrated to induce potent CD8 T cell responses in vivo. In this study, we investigated whether lentivector delivering a self/tumor Ag, tyrosinase related protein 1 (TRP1), could stimulate effective antitumor T cell responses. We found that immunization with lentivector expressing mutated TRP1 Ag elicited potent CD8 T cell responses against multiple TRP1 epitopes. Importantly, the activated CD8 T cells effectively recognize wild-type TRP1 epitopes. At peak times, as many as 10% of CD8 T cells were effector cells against TRP1 Ag. These cells killed wild-type TRP1 peptide-pulsed target cells in vivo and produced IFN-γ after ex vivo stimulation. The CD8 T cell responses were long-lasting (3–4 wk). Immunized mice were protected from B16 tumor cell challenge. In a therapeutic setting, lentivector immunization induced potent CD8 T cell responses in tumor bearing mice. The number of infiltrating T cells and the ratio of CD8/CD4 were dramatically increased in the tumors of immunized mice. The tumor-infiltrating CD8 T cells were functional and produced IFN-γ. The potent CD8 T cell responses stimulated by lentivector immunization eliminated small 3-day s.c. B16 tumors and strongly inhibited the growth of more established 5-day tumors. These studies demonstrate that genetic immunization with lentivector expressing mutated self/tumor Ag can generate potent CD8 T cell immune responses and antitumor immunity that prevent and inhibit B16 tumor growth, suggesting that lentivector immunization has the potential for tumor immunotherapy and immune prevention.
c-Maf Regulates IL-10 Expression during Th17 Polarization
Authors: Xu Jiangnan , Yang Yu , Qiu Guixing , Lal Girdhari , Wu Zhihong , Levy David E. , Ochando Jordi C. , Bromberg Jonathan S. , Ding Yaozhong
Published: May 2009

IL-10 production by Th17 cells is critical for limiting autoimmunity and inflammatory responses. Gene array analysis on Stat6 and T-bet double-deficient Th17 cells identified the Th2 transcription factor c-Maf to be synergistically up-regulated by IL-6 plus TGFβ and associated with Th17 IL-10 production. Both c-Maf and IL-10 induction during Th17 polarization depended on Stat3, but not Stat6 or Stat1, and mechanistically differed from IL-10 regulation by Th2 or IL-27 signals. TGFβ was also synergistic with IL-27 to induce c-Maf, and it induced Stat1-independent IL-10 expression in contrast to IL-27 alone. Retroviral transduction of c-Maf was able to induce IL-10 expression in Stat6-deficient CD4 and CD8 T cells, and c-Maf directly transactivated IL-10 gene expression through binding to a MARE (Maf recognition element) motif in the IL-10 promoter. Taken together, these data reveal a novel role for c-Maf in regulating T effector development, and they suggest that TGFβ may antagonize Th17 immunity by IL-10 production through c-Maf induction.
The Mucosal Adjuvant Effect of α-Galactosylceramide for Induction of Protective Immunity to Sexually Transmitted Viral Infection
Authors: Lindqvist Madelene , Persson Josefine , Thörn Karolina , Harandi Ali M.
Published: May 2009

Development of mucosal adjuvants to generate immunity in the female genital tract may have important implications for the development of vaccines to counter sexually transmitted infections. α-Galactosylceramide (α-GalCer) is presented by CD1d molecule on APCs to invariant Vα14+ NKT (iNKT) cells, which upon activation rapidly produce large amounts of immunomodulatory cytokines, leading to activation of a variety of innate and adaptive immune cells. Here, we assessed whether α-GalCer could act as a mucosal adjuvant for induction of protective immunity against genital herpes. We found that intranasal immunization with HSV-2 glycoprotein D (gD) in combination with α-GalCer elicits strong systemic gD-specific IgG Ab response as well as lymphoproliferative response with a mixed Th1/Th2 cytokine profile in the spleen, mediastinal lymph nodes, and genital lymph nodes. Importantly, such an immunization scheme conferred complete protection against an otherwise lethal vaginal HSV-2 challenge. We could also show that intravaginal immunization with gD plus α-GalCer generates potent gD-specific lymphoproliferative and IFN-γ responses in the genital lymph nodes and spleen. Furthermore, the vaginally immunized mice developed a strong systemic and mucosal IgG Ab response and protection against vaginal HSV-2 challenge. The mucosal adjuvant effect of α-GalCer was found to be mediated via CD1d molecule and appeared to be independent of the usage of the adaptor molecule MyD88. To our knowledge, this is the first report on the mucosal adjuvant effect of α-GalCer for induction of protective immunity against a sexually transmitted pathogen.
Shiga Toxin Activates Complement and Binds Factor H: Evidence for an Active Role of Complement in Hemolytic Uremic Syndrome
Authors: Orth Dorothea , Khan Abdul Basit , Naim Asma , Grif Katharina , Brockmeyer Jens , Karch Helge , Joannidis Michael , Clark Simon J. , Day Anthony J. , Fidanzi Sonja , Stoiber Heribert , Dierich Manfred P. , Zimmerhackl Lothar B. , Würzner Reinhard
Published: May 2009

Infections with enterohemorrhagic Escherichia coli (EHEC) are a major cause of hemolytic uremic syndrome (HUS). Shiga toxins (Stxs), especially Stx2, are believed to represent major virulence factors of EHEC, contributing to HUS pathogenesis. Beside EHEC-associated HUS, there are hereditary atypical forms of HUS, which are mostly caused by mutations of complement regulators. The aim of the present study was to investigate whether or not complement is also involved in the pathogenesis of EHEC-induced typical HUS, by being activated either directly or indirectly by involvement of its inhibitors. Purified Stx2 markedly activated complement via the alternative pathway and was found to bind to factor H (FH), however, only when it was active. No apparent cleavage or destruction of FH was visible, and cofactor activity in fluid phase was unaffected, but clearly delayed for surface-attached FH, where it is essential for host cell protection. Binding studies using FH constructs revealed that Stx2 binds to short consensus repeats (SCRs) 6–8 and SCRs18–20, but not to SCRs16–17, i.e., to regions involved in the surface recognition function of FH. In conclusion, complement, and in particular FH, not only plays an important role in atypical HUS, but most probably also in EHEC-induced HUS.
Adenovirus Vector-Induced Immune Responses in Nonhuman Primates: Responses to Prime Boost Regimens
Authors: Tatsis Nia , Lasaro Marcio O. , Lin Shih-Wen , Xiang Zhi Q. , Zhou Dongming , DiMenna Lauren , Li Hua , Bian Ang , Abdulla Sarah , Li Yan , Giles-Davis Wynetta , Engram Jessica , Ratcliffe Sarah J. , Silvestri Guido , Ertl Hildegund C. , Betts Michael R.
Published: May 2009

In the phase IIb STEP trial an HIV-1 vaccine based on adenovirus (Ad) vectors of the human serotype 5 (AdHu5) not only failed to induce protection but also increased susceptibility to HIV-1 infection in individuals with preexisting neutralizing Abs against AdHu5. The mechanisms underlying the increased HIV-1 acquisition rates have not yet been elucidated. Furthermore, it remains unclear if the lack of the vaccine’s efficacy reflects a failure of the concept of T cell-mediated protection against HIV-1 or a product failure of the vaccine. Here, we compared two vaccine regimens based on sequential use of AdHu5 vectors or two different chimpanzee-derived Ad vectors in rhesus macaques that were AdHu5 seropositive or seronegative at the onset of vaccination. Our results show that heterologous booster immunizations with the chimpanzee-derived Ad vectors induced higher T and B cell responses than did repeated immunizations with the AdHu5 vector, especially in AdHu5-preexposed macaques.
Cutting Edge: IL-23 Receptor GFP Reporter Mice Reveal Distinct Populations of IL-17-Producing Cells
Authors: Awasthi Amit , Riol-Blanco Lorena , Jäger Anneli , Korn Thomas , Pot Caroline , Galileos George , Bettelli Estelle , Kuchroo Vijay K. , Oukka Mohamed
Published: May 2009

IL-23, an IL-12 family member, has been implicated in the development of Th17 cells and the progression of autoimmune diseases. However, due to the lack of availability of sensitive Ab reagents specific for the IL-23 receptor (IL-23R), it has been difficult to characterize the cell types that express the IL-23R and are responsive to IL-23 in vivo. To address the role of IL-23 in vivo, we have generated a novel “knock-in” mouse in which we have replaced the intracellular domain of the IL-23R with the GFP. We show that in addition to Th17 cells, a subset of myeloid cells express IL-23R and respond to IL-23 by producing IL-17 and IL-22. Our studies further demonstrate that IL-23R expression is crucial for generation of encephalitogenic Th17 cells, but its expression on the innate immune system is dispensible in the development of experimental autoimmune encephalomyelitis.
Challenges and opportunities for Korean missionaries in Southern Africa
Authors: Oh Kyung H. , Meiring Piet G.J.
Published: May 2009

This article describes the history of missions in Korea as well as the challenges and opportunities for Korean missionaries in Southern Africa. The most significant problems encountered by Korean missionaries include understanding local context, language and culture acquisition, and meeting the expectations of local people and local churches as well as those of sending churches in Korea. On a personal level, missionaries have to cope with family concerns, maintaining their spiritual life, health problems, financial concerns, frustrations and unfulfilled ideals. Korean missionaries in Southern Africa do, however, have a unique opportunity to serve the Church in its mission and, above all, to serve the Lord of the Church in his mission, although there are indeed difficulties to overcome and challenges to face.
Synthesis of the New 7S‐Aminolentiginosine and Derivatives
Authors: Cordero Franca M. , Bonanno Paola , Neudeck Sven , Vurchio Carolina , Brandi Alberto
Published: April 2009

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The new 7S‐aminolentiginosine has been synthesized by a diastereoselective 1,3‐dipolar cycloaddition strategy starting from 3,4‐dihydroxylated pyrroline N‐oxides derived from L‐tartaric acid in thirteen steps. The intermediate 7S‐azidolentiginosine undergoes efficiently copper(I)‐catalysed Huisgen cycloadditions to alkynes.
Reaction of Bis(alkynyl)silanes with Tris(pentafluorophenyl)borane: Synthesis of Bulky Silole Derivatives by Means of 1,1‐Carboboration under Mild Reaction Conditions
Authors: Dierker Gereon , Ugolotti Juri , Kehr Gerald , Fröhlich Roland , Erker Gerhard
Published: April 2009

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The strong Lewis acid tris(pentafluorophenyl)borane [B(C6F5)3] reacts rapidly with dimethylbis(phenylethynyl)silane (1c) at room temperature in toluene by shift of a pentafluorophenyl (C6F5) group and formation of a new carbon‐bis(pentafluorophenyl)boron linkage [CB(C6F5)2] in a sequence of 1,1‐carboboration reactions to yield the 4‐bis(pentafluorophenyl)boryl/3‐pentafluorophenyl‐substituted 1,1‐dimethyl‐2,5‐diphenylsilole derivative 7c. The analogous reaction of bis(trimethylsilylethynyl)diphenylsilane (1d) with tris(pentafluorophenyl)borane gave the corresponding boryl‐substituted silole derivative (7d) featuring six bulky substituents attached at the central heterocyclic framework. Both the starting materials (1c, 1d) and the products (7c, 7d) were characterized by X‐ray crystal structure analyses.
A Xenon‐129 Biosensor for Monitoring MHC–Peptide Interactions
Authors: Schlundt Andreas , Kilian Wolfgang , Beyermann Michael , Sticht Jana , Günther Sebastian , Höpner Sabine , Falk Kirsten , Roetzschke Olaf , Mitschang Lorenz , Freund Christian
Published: April 2009

Die Komplexbildung zwischen einem Peptidliganden und einem MHC‐Klasse‐II‐Protein wird mithilfe eines 129Xe‐Biosensors nachgewiesen. Cryptophanmoleküle, die Xe‐Atome einfangen, werden mit einem Hämagglutinin(HA)‐Peptid modifiziert, das an das MHC‐Protein bindet. Die Wechselwirkung kann anhand einer Veränderung der chemischen Verschiebung von Käfig‐HA‐gebundenem 129Xe verfolgt werden.

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Development of a Fluorescent Pb2+ Sensor
Authors: Marbella Lauren , Serli‐Mitasev Barbara , Basu Partha
Published: April 2009

Hochgefahren wird die Emissionsintensität des Heterocyclus 1 beim Binden an Pb2+. Damit fungiert 1 als niedermolekularer „Anschalt“‐Fluoreszenzsensor für Blei. Der Sensor ist hochselektiv und funktioniert über einen großen pH‐Bereich.

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Linear π‐Acceptor‐Templated Dynamic Clipping to Macrobicycles and [2]Rotaxanes
Authors: Klivansky Liana M. , Koshkakaryan Gayane , Cao Dennis , Liu Yi
Published: April 2009

Sperr mich ein! Ein lineares, hantelförmiges Bipyridiniummolekül kann als Templat für die Bildung eines Käfigs um sich selbst herum mithilfe von sechs Iminbindungen wirken. Dabei entsteht als einziges Produkt ein verzahntes [2]Rotaxan (siehe Bild). Diese hocheffiziente [2+3]‐Klammerung tritt trotz der fehlenden Symmetrieähnlichkeit von Templat und gebildetem Makrobicyclus auf.

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