bluuebunny/crossref_metadata_2025 huggingface dataset:
Proangiogenic Function of CD40 Ligand-CD40 Interactions
Authors: Reinders Marlies E. J. , Sho Masayuki , Robertson Stuart W. , Geehan Christopher S. , Briscoe David M.
Published: April 2014

Angiogenesis is a characteristic component of cell-mediated immune inflammation. However, little is known of the immunologic mediators of angiogenesis factor production. Interactions between CD40 ligand (CD40L) and CD40 have been shown to have pluripotent functions in inflammation, including the production of cytokines, chemokines, as well as the angiogenesis factor, vascular endothelial growth factor (VEGF), by endothelial cells. In this study we found that treatment of cultured human endothelial cells with an anti-CD40 Ab (to ligate CD40) resulted in the expression of several other angiogenesis factors, including fibroblast growth factor-2 and the receptors Flt-1 and Flt-4. To determine the proangiogenic effect of CD40L in vivo, human skin was allowed to engraft on SCID mice for 6 wk. These healed human skins express CD40 on resident endothelial cells and monocyte/macrophages, but not on CD20-expressing B cells. Skins were injected with saline, untransfected murine fibroblasts, or murine fibroblasts stably transfected with human CD40L. We found that the injection of CD40L-expressing cells, but not control cells, resulted in the in vivo expression of several angiogenesis factors (including VEGF and fibroblast growth factor) and a marked angiogenesis reaction. Mice treated with anti-VEGF failed to elicit an angiogenesis reaction in response to injection of CD40L-expressing cells, suggesting that the proangiogenic effect of CD40L in vivo is VEGF dependent. These observations imply that ligation of CD40 at a peripheral inflammatory site is of pathophysiological importance as a mediator of both angiogenesis and inflammation.
Role of Regulator of G Protein Signaling 16 in Inflammation- Induced T Lymphocyte Migration and Activation
Authors: Lippert Eric , Yowe David L. , Gonzalo Jose-Angel , Justice J. Paul , Webster Jeremy M. , Fedyk Eric R. , Hodge Martin , Miller Cheryl , Gutierrez-Ramos Jose-Carlos , Borrego Francisco , Keane-Myers Andrea , Druey Kirk M.
Published: April 2014

Chemokine-induced T lymphocyte recruitment to the lung is critical for allergic inflammation, but chemokine signaling pathways are incompletely understood. Regulator of G protein signaling (RGS)16, a GTPase accelerator (GTPase-activating protein) for Gα subunits, attenuates signaling by chemokine receptors in T lymphocytes, suggesting a role in the regulation of lymphocyte trafficking. To explore the role of RGS16 in T lymphocyte-dependent immune responses in a whole-organism model, we generated transgenic (Tg) mice expressing RGS16 in CD4+ and CD8+ cells. rgs16 Tg T lymphocytes migrated to CC chemokine ligand 21 or CC chemokine ligand 12 injection sites in the peritoneum, but not to CXC chemokine ligand 12. In a Th2-dependent model of allergic pulmonary inflammation, CD4+ lymphocytes bearing CCR3, CCR5, and CXCR4 trafficked in reduced numbers to the lung after acute inhalation challenge with allergen (OVA). In contrast, spleens of sensitized and challenged Tg mice contained increased numbers of CD4+CCR3+ cells producing more Th2-type cytokines (IL-4, IL-5, and IL-13), which were associated with increased airway hyperreactivity. Migration of Tg lymphocytes to the lung parenchyma after adoptive transfer was significantly reduced compared with wild-type lymphocytes. Naive lymphocytes displayed normal CCR3 and CXCR4 expression and cytokine responses, and compartmentation in secondary lymphoid organs was normal without allergen challenge. These results suggest that RGS16 may regulate T lymphocyte activation in response to inflammatory stimuli and migration induced by CXCR4, CCR3, and CCR5, but not CCR2 or CCR7.
Complement Activation Determines the Therapeutic Activity of Rituximab In Vivo
Authors: Di Gaetano Nicola , Cittera Elena , Nota Rachele , Vecchi Annunciata , Grieco Valeria , Scanziani Eugenio , Botto Marina , Introna Martino , Golay Josée
Published: April 2014

Rituximab is an anti-CD20 chimeric mAb effective for the treatment of B-NHL. It can lyse lymphoma cells in vitro through both C- and Ab-dependent cellular cytotoxicity. The mechanism of action of rituximab in vivo is however still unclear. We have set up a new in vivo model in nonimmunodeficient mice by stable transduction of the human CD20 cDNA in the murine lymphoma line EL4. Animals injected i.v. with the EL4-CD20+ lymphoma cells died within 30 days with evident liver, spleen, and bone marrow involvement, confirmed by immunohistochemistry and PCR analysis. A single injection of rituximab or the murine anti-CD20 Ab 1F5, given i.p. 1 day after the tumor, cured 100% of the animals. Indeed, at week 4 after tumor cell inoculation, CD20+ cells were undetectable in all organs analyzed in rituximab-treated animals, as determined by immunohistochemistry and PCR. Rituximab had no direct effect on tumor growth in vitro. Depletion of either NK cells or neutrophils or both in tumor-injected animals did not affect the therapeutic activity of the drug. Similarly, rituximab was able to eradicate tumor cells in athymic nude mice, suggesting that its activity is T cell independent. In contrast, the protective activity of rituximab or the 1F5 Ab was completely abolished in syngeneic knockout animals lacking C1q, the first component of the classical pathway of C (C1qa−/−). These data demonstrate that C activation is fundamental for rituximab therapeutic activity in vivo.
HER-2 DNA and Protein Vaccines Containing Potent Th Cell Epitopes Induce Distinct Protective and Therapeutic Antitumor Responses in HER-2 Transgenic Mice
Authors: Renard Valéry , Sonderbye Lene , Ebbehøj Kirsten , Rasmussen Peter Birk , Gregorius Klaus , Gottschalk Tine , Mouritsen Søren , Gautam Anand , Leach Dana R.
Published: April 2014

Overexpression of the growth factor receptor HER-2 (c-erbB-2, neu) has transforming potential and occurs in ∼20–30% of breast and ovarian cancers. HER-2 is a self Ag, but Abs and T cells specific for HER-2 have been isolated from cancer patients, suggesting HER-2 may be a good target for active immunotherapy. We constructed rat HER-2 DNA and protein vaccines containing potent Th cell epitopes derived from tetanus toxin and studied their potency in two strains of mice transgenic for the rat HER-2 molecule. Vaccination with HER-2 DNA protected nontransgenic mice from tumor challenge, but induced only moderate protection in one of the tumor models. However, vaccination with the modified HER-2 protein resulted in almost complete protection from tumor challenge in both tumor models. This protection could be mediated by Abs alone. In addition, protein vaccination efficiently eliminated pre-established tumors in both models, even when vaccination occurred 9 days after tumor implantation. These data demonstrate the potential of HER-2-based vaccines as therapeutic agents for the treatment of cancers overexpressing HER-2.
Microglia-Mediated Nitric Oxide Cytotoxicity of T Cells Following Amyloid β-Peptide Presentation to Th1 Cells
Authors: Monsonego Alon , Imitola Jaime , Zota Victor , Oida Takatoku , Weiner Howard L.
Published: April 2014

Alzheimer’s disease is marked by progressive accumulation of amyloid β-peptide (Aβ) which appears to trigger neurotoxic and inflammatory cascades. Substantial activation of microglia as part of a local innate immune response is prominent at sites of Aβ plaques in the CNS. However, the role of activated microglia as Aβ APCs and the induction of adaptive immune responses has not been investigated. We have used primary microglial cultures to characterize Aβ-Ag presentation and interaction with Aβ-specific T cells. We found that IFN-γ-treated microglia serve as efficient Aβ APCs of both Aβ1–40 and Aβ1–42, mediating CD86-dependent proliferation of Aβ-reactive T cells. When cultured with Th1 and Th2 subsets of Aβ-reactive T cells, Th1, but not Th2, cells, underwent apoptosis after stimulation, which was accompanied by increased levels of IFN-γ, NO, and caspase-3. T cell apoptosis was prevented in the presence of an inducible NO synthase type 2 inhibitor. Microglia-mediated proliferation of Aβ-reactive Th2 cells was associated with expression of the Th2 cytokines IL-4 and IL-10, which counterbalanced the toxic levels of NO induced by Aβ. Our results demonstrate NO-dependent apoptosis of T cells by Aβ-stimulated microglia which may enhance CNS innate immune responses and neurotoxicity in Alzheimer’s disease. Secretion of NO by stimulated microglia may underlie a more general pathway of T cell death in the CNS seen in neurodegenerative diseases. Furthermore, Th2 type T cell responses may have a beneficial effect on this process by down-regulation of NO and the proinflammatory environment.
Rapid High Efficiency Sensitization of CD8+ T Cells to Tumor Antigens by Dendritic Cells Leads to Enhanced Functional Avidity and Direct Tumor Recognition Through an IL-12-Dependent Mechanism
Authors: Xu Shuwen , Koski Gary K. , Faries Mark , Bedrosian Isabelle , Mick Rosemarie , Maeurer Markus , Cheever Martin A. , Cohen Peter A. , Czerniecki Brian J.
Published: April 2014

Myeloid-origin dendritic cells (DCs) can develop into IL-12-secreting DC1 or non-IL-12-secreting DC2 depending on signals received during maturation. Through rapid culture techniques that prepared either mature, CD83+ DC1 or DC2 from CD14+ monocytes in only 2 days followed by a single 6–7 day DC-T cell coculture, we sensitized normal donor CD8+ T cells to tumor Ags (HER-2/neu, MART-1, and gp100) such that peptide Ag-specific lymphocytes constituted up to 16% of the total CD8+ population. Both DC1 and DC2 could sensitize CD8+ T cells that recognized peptide-pulsed target cells. However, with DC2, a general decoupling was observed between recognition of peptide-pulsed T2 target cells and recognition of Ag-expressing tumor cells, with peptide-sensitized T cells responding to tumor only about 15% of the time. In contrast, direct recognition of tumor by T cells was dramatically increased (to 85%) when DC1 were used for sensitization. Enhanced tumor recognition was accompanied by 10- to 100-fold increases in peptide sensitivity and elevated expression of CD8β, characteristic of high functional avidity T cells. Both of these properties were IL-12-dependent. These results demonstrate the utility of rapid DC culture methods for high efficiency in vitro T cell sensitization that achieves robust priming and expansion of Ag-specific populations in 6 days. They also demonstrate a novel function of IL-12, which is enhancement of CD8+ T cell functional avidity. A new approach to DC-based vaccines that emphasizes IL-12 secretion to enhance functional avidity and concomitant tumor recognition by CD8+ T cells is indicated.
TNF Skews Monocyte Differentiation from Macrophages to Dendritic Cells
Authors: Chomarat Pascale , Dantin Carole , Bennett Lynda , Banchereau Jacques , Palucka A. Karolina
Published: April 2014

Monocytes represent a large pool of circulating precursors of APCs, both macrophages and dendritic cells (DCs). It is thus important to identify the mechanisms by which microenvironment regulates monocyte differentiation. We have previously shown that, upon contact with resting stromal cells such as fibroblasts, monocytes differentiate into macrophages in an IL-6/M-CSF-dependent fashion. Yet, in the inflamed tissue, monocytes need to yield DCs for the adaptive immunity to be induced. Inasmuch as TNF and IL-1 are present at the site of inflammation, we tested their capacity to modulate monocyte differentiation into either macrophages or DCs. TNF, but not IL-1, induce monocytes to become DCs despite the presence of fibroblasts. TNF-induced DCs contain Langerin-positive cells and are able to induce allogenic T cell proliferation. Then, TNF was found to decrease the expression and internalization of the M-CSF receptor, thus overriding the IL-6/M-CSF pathway. Thus, TNF facilitates the induction of adaptive immunity by promoting DC differentiation not only from CD34+ progenitors but also from CD14+ blood precursors.
CD4+ Th Cells Resembling Regulatory T Cells That Inhibit Chronic Colitis Differentiate in the Absence of Interactions Between CD4 and Class II MHC
Authors: Denning Timothy L. , Qi Hai , König Rolf , Scott Kevin G. , Naganuma Makoto , Ernst Peter B.
Published: April 2014

Regulatory CD4+ Th cells can prevent many autoimmune diseases; however, the factors selecting for these cells remain poorly defined. In transgenic mice with a mutation in the CD4 binding region on class II MHC, the disruption of CD4-class II interactions selected for CD4+ Th cells that expressed surface markers and cytokines associated with regulatory Th cells. Th cells from these mice were enriched for CD45RBlow as well as CD25+, while they expressed high levels of the transcription factor associated with regulatory T cells, Foxp3, and cytokines, including IL-4, IL-10, and IFN-γ mRNA and protein. These regulatory Th cells inhibited the function of APCs via IL-10 production, and adoptive transfer of these cells prevented weight loss and inflammation in a model of colitis. CD4+ regulatory Th cells emerged only when interactions between CD4 and class II MHC were deficient on cells of nonhemopoietic origin. These data support a novel model controlling the differentiation of regulatory Th cells and suggest that interactions between CD4 and class II MHC may a useful target for re-educating T cells as a treatment for inflammatory diseases.
Regulation of Sustained Actin Dynamics by the TCR and Costimulation as a Mechanism of Receptor Localization
Authors: Tskvitaria-Fuller Irina , Rozelle Andrew L. , Yin Helen L. , Wülfing Christoph
Published: April 2014

The localization of receptors, signaling intermediates, and cytoskeletal components at the T cell/APC interface is thought to be a major determinant of efficient T cell activation. However, important questions remain open. What are the dynamics of the T cell cytoskeleton as a potential mediator of such localization? How are they regulated by the TCR and costimulatory receptors? Do they actually mediate receptor localization? In this study, we have addressed these questions. Even under limiting T cell activation conditions, actin accumulated immediately and transiently at the T cell/APC interface, the microtubule organizing center reoriented toward it. In contrast, sustained (>5 min) actin accumulation in highly dynamic patterns depended on an optimal T cell stimulus: high concentrations of the strong TCR ligand agonist peptide/MHC and engagement of the costimulatory receptors CD28 and LFA-1 were required in an overlapping, yet distinct, fashion. Intact sustained actin dynamics were required for interface accumulation of TCR/MHC in a central pattern and for efficient T cell proliferation, as established using a novel approach to selectively block only the sustained actin dynamics. These data suggest that control of specific elements of actin dynamics by TCR and costimulatory receptors is a mechanism to regulate the efficiency of T cell activation.
Surface Expression of Notch1 on Thymocytes: Correlation with the Double-Negative to Double-Positive Transition
Authors: Huang Eugene Y. , Gallegos Alena M. , Richards Sabrina M. , Lehar Sophie M. , Bevan Michael J.
Published: April 2014

Notch1 plays a critical role in regulating T lineage commitment during the differentiation of lymphoid precursors. The physiological relevance of Notch1 signaling during subsequent stages of T cell differentiation has been more controversial. This is due in part to conflicting data from studies examining the overexpression or targeted deletion of Notch1 and to difficulties in distinguishing between the activities of multiple Notch family members and their ligands, which are expressed in the thymus. We employed a polyclonal antiserum against the extracellular domain of Notch1 to study surface expression during thymopoiesis. We found high levels of Notch1 on the cell surface only on double negative (DN) stage 2 through the immature single-positive stage of thymocyte development, before the double-positive (DP) stage. The Notch signaling pathway, as read out by Deltex1 expression levels, is highly active in DN thymocytes. When an active Notch1 transgene, Notch1IC, is exogenously introduced into thymocytes of recombinase-activating gene 2-deficient mice, it promotes proliferation and development to the DP stage following anti-CD3 treatment without apparently affecting the intensity of pre-TCR signaling. In addition, a stromal cell line expressing the Notch ligand, Delta-like-1, promotes the in vitro expansion of wild-type DN3 thymocytes in vitro. Consistent with other recent reports, these data suggest a role for Notch1 during the DN to DP stage of thymocyte maturation and suggest a cellular mechanism by which Notch1IC oncogenes could contribute to thymoma development and maintenance.
CpG DNA Induces a Class II Transactivator-Independent Increase in Class II MHC by Stabilizing Class II MHC mRNA in B Lymphocytes
Authors: Kuchtey John , Pennini Meghan , Pai Rish K. , Harding Clifford V.
Published: April 2014

Microbial products, such as CpG DNA and LPS, enhance class II MHC (MHC-II) expression and Ag presentation by dendritic cells, but this effect does not occur with macrophages and is largely unexplored in B cells. Although MHC-II expression is influenced by transcriptional regulation, which is governed by class II transactivator (CIITA) in all cells, microbial products enhance MHC-II expression by dendritic cells in part by increasing MHC-II protein stability. In this study, we show that the CpG-induced increase in MHC-II expression by B lymphocytes is not due to protein stabilization or changes in CIITA expression or activity, but instead is due to increased stability of MHC-II mRNA. This CIITA-independent mechanism adds a new layer of complexity to regulation of MHC-II and may increase T cell help for B cell Ab responses to microbial or vaccine Ags.
Interaction of Murine Precursor B Cell Receptor with Stroma Cells Is Controlled by the Unique Tail of λ5 and Stroma Cell-Associated Heparan Sulfate
Authors: Bradl Harald , Wittmann Jürgen , Milius Doreen , Vettermann Christian , Jäck Hans-Martin
Published: April 2014

Efficient clonal expansion of early precursor B (pre-B) cells requires signals delivered by an Ig-like integral membrane complex, the so-called pre-B cell receptor (pre-BCR). A pre-BCR consists of two membrane μH chains, two covalently associated surrogate L chains, and the heterodimeric signaling transducer Igαβ. In contrast to a conventional Ig L chain, the surrogate L chain is a heterodimer composed of the invariant polypeptides VpreB and λ5. Although it is still unclear how pre-BCR signals are initiated, two recent findings support a ligand-dependent initiation of pre-BCR signals: 1) a pre-BCR/galectin-1 interaction is required to induce phosphorylation of Igαβ in a human precursor B line, and 2) soluble murine as well as human pre-BCR molecules bind to stroma and other adherent cells. In this study, we show that efficient binding of a soluble murine pre-BCR to stroma cells requires the non-Ig-like unique tail of λ5. Surprisingly however, a murine pre-BCR, in contrast to its human counterpart, does not interact with galectin-1, as revealed by lactose blocking, RNA interference, and immunoprecipitation assays. Finally, the binding of a murine pre-BCR to stroma cells can be blocked either with heparin or by pretreatment of stroma cells with heparitinase or a sulfation inhibitor. Hence, efficient binding of a murine pre-BCR to stroma cells requires the unique tail of λ5 and stroma cell-associated heparan sulfate. These findings not only identified heparan sulfate as potential pre-BCR ligands, but will also facilitate the development of appropriate animal models to determine whether a pre-BCR/heparan sulfate interaction is involved in early B cell maturation.
Cholera Toxin Promotes the Induction of Regulatory T Cells Specific for Bystander Antigens by Modulating Dendritic Cell Activation
Authors: Lavelle Ed C. , McNeela Edel , Armstrong Michelle E. , Leavy Olive , Higgins Sarah C. , Mills Kingston H. G.
Published: April 2014

It has previously been reported that cholera toxin (CT) is a potent mucosal adjuvant that enhances Th2 or mixed Th1/Th2 type responses to coadministered foreign Ag. Here we demonstrate that CT also promotes the generation of regulatory T (Tr) cells against bystander Ag. Parenteral immunization of mice with Ag in the presence of CT induced T cells that secreted high levels of IL-4 and IL-10 and lower levels of IL-5 and IFN-γ. Ag-specific CD4+ T cell lines and clones generated from these mice had cytokine profiles characteristic of Th2 or type 1 Tr cells, and these T cells suppressed IFN-γ production by Th1 cells. Furthermore, adoptive transfer of bone marrow-derived dendritic cells (DC) incubated with Ag and CT induced T cells that secreted IL-4 and IL-10 and low concentrations of IL-5. It has previously been shown that IL-10 promotes the differentiation or expansion of type 1 Tr cells. Here we found that CT synergized with low doses of LPS to induce IL-10 production by immature DC. CT also enhanced the expression of CD80, CD86, and OX40 (CD134) on DC and induced the secretion of the chemokine, macrophage inflammatory protein-2 (MIP-2), but inhibited LPS-driven induction of CD40 and ICAM-I expression and production of the inflammatory cytokines/chemokines IL-12, TNF-α, MIP-1α, MIP-1β, and monocyte chemoattractant protein-1. Our findings suggest that CT induces maturation of DC, but, by inducing IL-10, inhibiting IL-12, and selectively affecting surface marker expression, suppresses the generation of Th1 cells and promotes the induction of T cells with regulatory activity.
A Transgenic Mouse Model Genetically Tags All Activated CD8 T Cells
Authors: Maris Charles H. , Miller Joseph D. , Altman John D. , Jacob Joshy
Published: April 2014

Identifying and characterizing Ag-specific CD8+ T cells are central to the study of immunological memory. Although powerful strategies such as MHC tetramers and peptide-induced cytokine production assays exist for identifying Ag-specific CD8+ T cells, alternate strategies that are not dependent upon a priori knowledge of the immunodominant and subdominant antigenic epitopes, as well as the MHC background of the animal are of obvious utility. In this study, we present a transgenic mouse model that uses Cre-loxP recombination to permanently mark all activated CD8+ T cells with β-galactosidase. We used the lymphocytic choriomeningitis virus infection model to track the dynamics of the antiviral CD8+ T cell responses. We show that in this transgenic mouse model system, all of the antiviral effector and memory CD8+ T cells are contained within the β-gal-marked CD8+ T cell population.
Most IL-4-Producing γδ Thymocytes of Adult Mice Originate from Fetal Precursors
Authors: Grigoriadou Kalliopi , Boucontet Laurent , Pereira Pablo
Published: April 2014

Thy-1dull γδ T cells constitute a distinct adult γδ T cell subset characterized by the expression of a TCR composed of Vγ1Cγ4 and Vδ6Cδ chains with limited junctional sequence diversity. However, several features of the expressed Thy-1dull TCR-γδ genes, in particular the absence or minimal presence of N region diversity and the almost invariable Dδ2-Jδ1 junction, are typical of rearrangements often found in the fetal thymus. In this study, we have investigated the origin of these cells. Few Thy-1dull γδ thymocytes developed in syngeneic radiation adult chimeras, regardless of whether the recipient mice were given adult bone marrow or fetal liver cells as a source of hemopoietic precursors. In contrast, normal numbers of Thy-1dull γδ T cells developed in fetal thymi grafted into adult syngeneic recipients. Interestingly, the majority of Thy-1dull γδ thymocytes present in the grafts were of graft origin, even when most conventional γδ and αβ thymocytes in the grafted thymi originated from T cell precursors of recipient origin. Single-cell PCR analyses of the nonselected TCR-γ rearrangements present in adult Thy-1dull γδ thymocytes revealed that more than one-half of these cells represent the progenies of a limited number of clones that greatly expanded possibly during the first weeks of life. Finally, the second TCR-δ allele of a large number of Thy-1dull γδ Τ cells contained incomplete TCR-δ rearrangements, thus providing an explanation for the adult-type rearrangements previously found among nonfunctional V(D)J rearrangements present in Thy-1dull γδ thymocytes.
TCR Binding Kinetics Measured with MHC Class I Tetramers Reveal a Positive Selecting Peptide with Relatively High Affinity for TCR
Authors: Holmberg Kaisa , Mariathasan Sanjeev , Ohteki Toshiaki , Ohashi Pamela S. , Gascoigne Nicholas R. J.
Published: April 2014

The interaction between TCR and peptide-MHC (pMHC) complexes is crucial for the activation of T cells as well as for positive and negative selection in the thymus. The kinetics and affinity of this interaction and the densities of TCR and pMHC complexes on the cell surface are determining factors for different outcomes during thymic selection. In general, it is thought that agonist pMHC, which cause negative selection, have higher affinities and, in particular, slower off-rates than partial or weak agonists and antagonists, which cause positive selection. In this study, we have used pMHC tetramers to investigate the kinetics of TCR-pMHC interaction for agonist, weak agonist, and antagonist ligands of the anti-lymphocytic choriomeningitis virus P14 TCR. Kinetics determined on the cell surface may be biologically more relevant than methods using soluble proteins. We can distinguish between agonists and weak agonists or antagonists based on the half-life and the avidity of tetramer-TCR interaction. Furthermore, we show that a weak agonist self-peptide that positively selects P14 TCR+ thymocytes has a tetramer half-life and avidity only slightly weaker than strong agonists. We show that, in fact, it can act as quite a strong agonist, but that its poor ability to stabilize MHC causes it instead to have a weak agonist phenotype.
Molecular Cloning of C4 Gene and Identification of the Class III Complement Region in the Shark MHC
Authors: Terado Tokio , Okamura Kazuhiko , Ohta Yuko , Shin Dong-Ho , Smith Sylvia L. , Hashimoto Keiichiro , Takemoto Tadashi , Nonaka Mayumi I. , Kimura Hiroshi , Flajnik Martin F. , Nonaka Masaru
Published: April 2014

To clarify the evolutionary origin of the linkage of the MHC class III complement genes with the MHC class I and II genes, we isolated C4 cDNA from the banded hound shark (Triakis scyllium). Upon phylogenetic tree analysis, shark C4 formed a well-supported cluster with C4 of higher vertebrates, indicating that the C3/C4 gene duplication predated the divergence of cartilaginous fish from the main line of vertebrate evolution. The deduced amino acid sequence predicted the typical C4 three-subunits chain structure, but without the histidine residue catalytic for the thioester bond, suggesting the human C4A-like specificity. The linkage analysis of the complement genes, one C4 and two factor B (Bf) genes, to the shark MHC was performed using 56 siblings from two typing panels of T. scyllium and Ginglymostoma cirratum. The C4 and one of two Bf genes showed a perfect cosegregation with the class I and II genes, whereas two recombinants were identified for the other Bf gene. These results indicate that the linkage between the complement C4 and Bf genes, as well as the linkage between these complement genes and the MHC class I and II genes were established before the emergence of cartilaginous fish >460 million years ago.
T Cell Recognition of Distinct Peptide:I-Au Conformers in Murine Experimental Autoimmune Encephalomyelitis
Authors: Huang Jason C. , Han Mei , Minguela Alfredo , Pastor Silvia , Qadri Ayub , Ward E. Sally
Published: April 2014

We have used T cells bearing TCRs that are closely related in sequence as probes to detect conformational variants of peptide-MHC complexes in murine experimental autoimmune encephalomyelitis in H-2u mice. The N-terminal epitope of myelin basic protein (MBP) is immunodominant in this model. Our studies have primarily focused on T cell recognition of a position 4 analog of this peptide (MBP1–9[4Y]) complexed with I-Au. Using site-directed mutagenesis, we have mapped the functionally important complementarity determining region residues of the 1934.4 TCR Vα domain. One of the resulting mutants (Tyr95 to alanine in CDR3α, Y95A) has interesting properties: relative to the parent wild-type TCR, this mutant poorly recognizes Ag complexes generated by pulsing professional APCs (PL-8 cells) with MBP1–9[4Y] while retaining recognition of MBP1–9[4Y]-pulsed unconventional APCs or insect cell-expressed complexes of I-Au containing tethered MBP1–9[4Y]. Insect cell expression of recombinant I-Au with covalently tethered class II-associated invariant chain peptide or other peptides which bind relatively weakly, followed by proteolytic cleavage of the peptide linker and replacement by MBP1–9[4Y] in vitro, results in complexes that resemble peptide-pulsed PL-8 cells. Therefore, the distinct conformers can be produced in recombinant form. T cells that can distinguish these two conformers can also be generated by the immunization of H-2u mice, indicating that differential recognition of the conformers is observed for responding T cells in vivo. These studies have relevance to understanding the molecular details of T cell recognition in murine experimental autoimmune encephalomyelitis. They are also of particular importance for the effective use of multimeric peptide-MHC complexes to characterize the properties of Ag-specific T cells.
Regulation of the Human High Affinity IgE Receptor β-Chain Gene Expression Via an Intronic Element
Authors: Takahashi Kyoko , Nishiyama Chiharu , Hasegawa Masanari , Akizawa Yushiro , Ra Chisei
Published: April 2014

The high affinity IgE receptor, FcεRI, is a key regulatory molecule in the allergic reaction. By screening for cis-acting elements over the entire region of the human FcεRI β-chain gene, a sequence located in the fourth intron was revealed to serve as a repressor element. This element was recognized by a transcription factor, myeloid zinc finger protein 1 (MZF-1). Introduction of MZF-1 antisense inhibited the suppressive effect of the element on the β-chain promoter and increased the mRNA for the β-chain in KU812 cells, indicating that MZF-1 repressed human FcεRI β-chain gene expression via the element in the fourth intron. Furthermore, it was suggested that a cofactor binding with MZF-1, whose expression level was different among the cell types, was required for transcriptional repression by MZF-1.
Functional Requirements for Interactions Between CD84 and Src Homology 2 Domain-Containing Proteins and Their Contribution to Human T Cell Activation
Authors: Tangye Stuart G. , Nichols Kim E. , Hare Nathan J. , van de Weerdt Barbara C. M.
Published: April 2014

Cell surface receptors belonging to the CD2 subset of the Ig superfamily of molecules include CD2, CD48, CD58, 2B4, signaling lymphocytic activation molecule (SLAM), Ly9, CD84, and the recently identified molecules NTB-A/Ly108/SLAM family (SF) 2000, CD84H-1/SF2001, B lymphocyte activator macrophage expressed (BLAME), and CRACC (CD2-like receptor-activating cytotoxic cells)/CS-1. Some of these receptors, such as CD2, SLAM, 2B4, CRACC, and NTB-A, contribute to the activation and effector function of T cells and NK cells. Signaling pathways elicited via some of these receptors are believed to involve the Src homology 2 (SH2) domain-containing cytoplasmic adaptor protein SLAM-associated protein (SAP), as it is recruited to SLAM, 2B4, CD84, NTB-A, and Ly-9. Importantly, mutations in SAP cause the inherited human immunodeficiency X-linked lymphoproliferative syndrome (XLP), suggesting that XLP may result from perturbed signaling via one or more of these SAP-associating receptors. We have now studied the requirements for SAP recruitment to CD84 and lymphocyte activation elicited following ligation of CD84 on primary and transformed human T cells. CD84 was found to be rapidly tyrosine phosphorylated following receptor ligation on activated T cells, an event that involved the Src kinase Lck. Phosphorylation of CD84 was indispensable for the recruitment of SAP, which was mediated by Y262 within the cytoplasmic domain of CD84 and by R32 within the SH2 domain of SAP. Furthermore, ligating CD84 enhanced the proliferation of anti-CD3 mAb-stimulated human T cells. Strikingly, this effect was also apparent in SAP-deficient T cells obtained from patients with XLP. These results reveal a novel function of CD84 on human lymphocytes and suggest that CD84 can activate human T cells via a SAP-independent mechanism.
The Block in Immunoglobulin Class Switch Recombination Caused by Activation-Induced Cytidine Deaminase Deficiency Occurs Prior to the Generation of DNA Double Strand Breaks in Switch μ Region
Authors: Catalan Nadia , Selz Françoise , Imai Kohsuke , Revy Patrick , Fischer Alain , Durandy Anne
Published: April 2014

Affinity maturation of the Ab repertoire in germinal centers leads to the selection of high affinity Abs with selected heavy chain constant regions. Ab maturation involves two modifications of the Ig genes, i.e., somatic hypermutation and class switch recombination. The mechanisms of these two processes are not fully understood. As shown by the somatic hypermutation and class switch recombination-deficient phenotype of activation-induced cytidine deaminase (AID)-deficient patients (hyperIgM type 2 syndrome) and mice, both processes require the AID molecule. Somatic DNA modifications require DNA breaks, which, at least for class switch recombination, lead to dsDNA breaks. By using a ligation-mediated PCR, it was found that class switch recombination-induced dsDNA breaks in Sμ switch regions were less frequent in AID-deficient B cells than in AID-proficient B cells, thus indicating that AID acts upstream of DNA break induction.
IFN-γ-Producing γδ T Cells Help Control Murine West Nile Virus Infection
Authors: Wang Tian , Scully Eileen , Yin Zhinan , Kim Jung H. , Wang Sha , Yan Jun , Mamula Mark , Anderson John F. , Craft Joe , Fikrig Erol
Published: April 2014

West Nile (WN) virus causes fatal meningoencephalitis in laboratory mice, thereby partially mimicking human disease. Using this model, we have demonstrated that mice deficient in γδ T cells are more susceptible to WN virus infection. TCRδ−/− mice have elevated viral loads and greater dissemination of the pathogen to the CNS. In wild-type mice, γδ T cells expanded significantly during WN virus infection, produced IFN-γ in ex vivo assays, and enhanced perforin expression by splenic T cells. Adoptive transfer of γδ T cells to TCRδ−/− mice reduced the susceptibility of these mice to WN virus, and this effect was primarily due to IFN-γ-producing γδ T cells. These data demonstrate a distinct role for γδ T cells in the control of and prevention of mortality from murine WN virus infection.
Functional Plasticity of Dendritic Cell Subsets as Mediated by CD40 Versus B7 Activation
Authors: Grohmann Ursula , Bianchi Roberta , Orabona Ciriana , Fallarino Francesca , Vacca Carmine , Micheletti Alessandra , Fioretti Maria C. , Puccetti Paolo
Published: April 2014

Murine dendritic cells (DCs) can present Ag in an immunogenic or tolerogenic fashion, the distinction depending on either the occurrence of specialized DC subsets or the maturation or activation state of the DC. Although DC subsets may be programmed to direct either tolerance or immunity, it is not known whether appropriate environmental stimulation can result in complete flexibility of a basic program. Using splenic CD8− and CD8+ DCs that mediate the respective immunogenic and tolerogenic presentation of self peptides, we show that both the in vivo and in vitro activities of either subset can be altered by ligation of specific surface receptors. Otherwise immunogenic CD8− DCs become tolerogenic upon B7 ligation by soluble CTLA-4, a maneuver that initiates immunosuppressive tryptophan catabolism. In contrast, CD40 ligation on tolerogenic CD8+ DCs makes these cells capable of immunogenic presentation. Thus, environmental conditioning by T cell ligands may alter the default function of DC subsets to meet the needs of flexibility and redundancy.
Blockade of S100A8 and S100A9 Suppresses Neutrophil Migration in Response to Lipopolysaccharide
Authors: Vandal Karen , Rouleau Pascal , Boivin Annie , Ryckman Carle , Talbot Mariève , Tessier Philippe A.
Published: April 2014

Recently, proinflammatory activities had been described for S100A8 and S100A9, two proteins found at inflammatory sites and within the neutrophil cytoplasm. In this study, we investigated the role of these proteins in neutrophil migration in vivo in response to LPS. LPS was injected into the murine air pouch, which led to the release of S100A8, S100A9, and S100A8/A9 in the pouch exudates that preceded accumulation of neutrophils. Passive immunization against S100A8 and S100A9 led to a 52% inhibition of neutrophil migration in response to LPS at 3 h postinjection. Injection of LPS was also associated with an increase in peripheral blood neutrophils and the presence in serum of S100A9 and S100A8/A9. Intravenous injection of S100A8, S100A9, or S100A8/A9 augmented the number of circulating neutrophils and diminished the number of neutrophils in the bone marrow, demonstrating that S100A8 and S100A9 induced the mobilization of neutrophils from the bone marrow to the blood. Finally, passive immunization with anti-S100A9 inhibited the neutrophilia associated with LPS injection in the air pouch. These results suggest that S100A8 and S100A9 play a role in the inflammatory response to LPS by inducing the release of neutrophils from the bone marrow and directing their migration to the inflammatory site.
Unique Effect of Arachidonic Acid on Human Neutrophil TNF Receptor Expression: Up-Regulation Involving Protein Kinase C, Extracellular Signal-Regulated Kinase, and Phospholipase A2
Authors: Moghaddami Nahid , Costabile Maurizio , Grover Phulwinder K. , Jersmann Hubertus P. A. , Huang Zhi H. , Hii Charles S. T. , Ferrante Antonio
Published: April 2014

Arachidonic acid (AA) regulates the function of many cell types, including neutrophils. Although much emphasis has been placed on agonist-induced down-regulation of TNFR, our data show that AA caused a rapid (10–20 min) and dose-dependent (0.5–30 μM) increase in the surface expression of both classes of TNFR (TNFR1 and TNFR2) on human neutrophils. This increased TNFR expression correlated with an increase in TNF-induced superoxide production. In contrast, the ω3 fatty acids eicosapentaenoic acid, docosahexaenoic acid, and linolenic acid failed to stimulate TNFR expression. Although fMLP and LPS reduced the neutrophil expression of TNFR, when pretreated with AA, fMLP caused an increase in TNFR expression. Consistent with this result was the finding that AA prevented the fMLP-induced receptor release in neutrophil cultures. AA also caused an increase in TNFR expression in matured HL-60 cells (neutrophil-like cells), but a decrease in nonmatured cells and HUVEC. The AA effects were independent of the lipoxygenase and cyclooxygenase pathways, but dependent on protein kinase C, the extracellular signal-regulated kinases 1 and 2, and cytosolic phospholipase A2. The data demonstrate a unique effect of AA in the inflammatory reaction, through its action on neutrophil TNFR expression, and suggest that AA may regulate the response of neutrophils to TNF by altering its receptor number.
Coevolution of Markers of Innate and Adaptive Immunity in Skin and Peripheral Blood of Patients with Erythema Migrans
Authors: Salazar Juan C. , Pope Constance D. , Sellati Timothy J. , Feder Henry M. , Kiely Thomas G. , Dardick Kenneth R. , Buckman Ronald L. , Moore Meagan W. , Caimano Melissa J. , Pope Jonathan G. , Krause Peter J. , Radolf Justin D. ,   The Lyme Disease Network
Published: April 2014

We used multiparameter flow cytometry to characterize leukocyte immunophenotypes and cytokines in skin and peripheral blood of patients with erythema migrans (EM). Dermal leukocytes and cytokines were assessed in fluids aspirated from epidermal suction blisters raised over EM lesions and skin of uninfected controls. Compared with corresponding peripheral blood, EM infiltrates were enriched for T cells, monocytes/macrophages, and dendritic cells (DCs), contained lower proportions of neutrophils, and were virtually devoid of B cells. Enhanced expression of CD14 and HLA-DR by lesional neutrophils and macrophages indicated that these innate effector cells were highly activated. Staining for CD45RO and CD27 revealed that lesional T lymphocytes were predominantly Ag-experienced cells; furthermore, a subset of circulating T cells also appeared to be neosensitized. Lesional DC subsets, CD11c+ (monocytoid) and CD11c− (plasmacytoid), expressed activation/maturation surface markers. Patients with multiple EM lesions had greater symptom scores and higher serum levels of IFN-α, TNF-α, and IL-2 than patients with solitary EM. IL-6 and IFN-γ were the predominant cytokines in EM lesions; however, greater levels of both mediators were detected in blister fluids from patients with isolated EM. Circulating monocytes displayed significant increases in surface expression of Toll-like receptor (TLR)1 and TLR2, while CD11c+ DCs showed increased expression of TLR2 and TLR4; lesional macrophages and CD11c+ and CD11c− DCs exhibited increases in expression of all three TLRs. These results demonstrate that Borrelia burgdorferi triggers innate and adaptive responses during early Lyme disease and emphasize the interdependence of these two arms of the immune response in the efforts of the host to contain spirochetal infection.
Most Highly Exposed Seronegative Men Lack HIV-1-Specific, IFN-γ-Secreting T Cells
Authors: Hladik Florian , Desbien Anthony , Lang Jean , Wang Lei , Ding Yan , Holte Sarah , Wilson Aaron , Xu Younong , Moerbe Micky , Schmechel Steve , McElrath M. Juliana
Published: April 2014

Naturally acquired cellular immunity in individuals who have been exposed to HIV-1 but have remained uninfected may hold clues for the design of an effective HIV vaccine. To determine the presence and nature of such an HIV-1-specific immune response, we evaluated the quantity and fine specificity of HIV-1-reactive IFN-γ-secreting T cells in a group of highly exposed seronegative men having sex with men. All 46 ES reported frequent unprotected anal sex with known HIV-1-infected partners at enrollment, and high risk activities continued in at least one-half of the volunteers for up to >6 years of observation. Despite the high frequency of unprotected anal intercourse and potential HIV-1 exposure, the vast majority of individuals demonstrated no or very low numbers of HIV-1-specific, IFN-γ-secreting T cells. Even when HIV-1 epitopes were presented by peptide-pulsed autologous dendritic cells in 15 of the highest risk volunteers, HIV-1-specific T cells remained infrequent, and the proportion of responders was not significantly different from that in a lower risk seronegative control cohort. Only PBMC from two individuals who have remained uninfected to date exhibited distinctly positive responses. However, these responses rarely persisted over time, single epitope specificities were identified in only one volunteer, and HIV-1-specific memory T cell clones did not expand in vitro. HIV-1-specific, IFN-γ-secreting T cells are thus unlikely to substantially contribute to resistance against infection in most exposed seronegative men having sex with men.
Genomic Effects of IFN-β in Multiple Sclerosis Patients
Authors: Weinstock-Guttman Bianca , Badgett Darlene , Patrick Kara , Hartrich Laura , Santos Roseane , Hall Dennis , Baier Monika , Feichter Joan , Ramanathan Murali
Published: April 2014

The purpose of this report was to characterize the dynamics of the gene expression cascades induced by an IFN-β-1a treatment regimen in multiple sclerosis patients and to examine the molecular mechanisms potentially capable of causing heterogeneity in response to therapy. In this open-label pharmacodynamic study design, peripheral blood was obtained from eight relapsing-remitting multiple sclerosis patients just before and at 1, 2, 4, 8, 24, 48, 120, and 168 h after i.m. injection of 30 μg of IFN-β-1a. The total RNA was isolated from monocyte-depleted PBL and analyzed using cDNA microarrays containing probes for >4000 known genes. IFN-β-1a treatment resulted in selective, time-dependent effects on multiple genes. The mRNAs for genes implicated in the anti-viral response, e.g., double-stranded RNA-dependent protein kinase, myxovirus resistance proteins 1 and 2, and guanylate binding proteins 1 and 2 were rapidly induced within 1–4 h of IFN-β treatment. The mRNAs for several genes involved in IFN-β signaling, such as IFN-α/β receptor-2 and Stat1, were also increased. The mRNAs for lymphocyte activation markers, such as IFN-induced transmembrane protein 1 (9–27), IFN-induced transmembrane protein 2 (1–8D), β2-microglobulin, and CD69, were also increased in a time-dependent manner. The findings demonstrate that IFN-β treatment induces specific and time-dependent changes in multiple mRNAs in lymphocytes of multiple sclerosis patients that could provide a framework for rapid monitoring of the response to therapy.
Cutting Edge: Diabetes-Associated Quantitative Trait Locus, Idd4, Is Responsible for the IL-12p40 Overexpression Defect in Nonobese Diabetic (NOD) Mice
Authors: Simpson Pedro B. , Mistry Monica S. , Maki Richard A. , Yang Weidong , Schwarz David A. , Johnson Eric B. , Lio Francisco M. , Alleva David G.
Published: April 2014

APCs of the nonobese diabetic (NOD) mouse have a genetically programmed capacity to overexpress IL-12p40, a cytokine critical for development of pathogenic autoreactive Th1 cells. To determine whether a diabetes-associated NOD chromosomal locus (i.e., Idd) was responsible for this defect, LPS-stimulated macrophages from several recombinant congenic inbred mice with Idd loci on a C57BL/6 background or with different combinations of NOD and CBA genomic segments were screened for IL-12p40 production. Only macrophages from the congenic strains containing the Idd4 locus showed IL-12p40 overproduction/expression. Moreover, analysis of IL-12p40 sequence polymorphisms demonstrated that the Idd4 intervals in these strains contained the IL-12p40 allele of the NOD, although further analysis is required to determine whether the IL-12p40 allele itself is responsible for its overexpression. Thus, the non-MHC-associated Idd4 locus appears responsible for IL-12p40 overexpression, which may be a predisposing factor for type 1 diabetes in NOD mice.
Cutting Edge: CD28 Controls Peripheral Homeostasis of CD4+CD25+ Regulatory T Cells
Authors: Tang Qizhi , Henriksen Kammi J. , Boden Elisa K. , Tooley Aaron J. , Ye Jianqin , Subudhi Sumit K. , Zheng Xin X. , Strom Terry B. , Bluestone Jeffrey A.
Published: April 2014

CD28/B7 blockade leads to exacerbated autoimmune disease in the nonobese diabetic mouse strain as a result of a marked reduction in the number of CD4+CD25+ regulatory T cells (Tregs). Herein, we demonstrate that CD28 controls both thymic development and peripheral homeostasis of Tregs. CD28 maintains a stable pool of peripheral Tregs by both supporting their survival and promoting their self-renewal. CD28 engagement promotes survival by regulating IL-2 production by conventional T cells and CD25 expression on Tregs.