bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dissecting the Structural Determinants of the Interaction between the Human Cytomegalovirus UL18 Protein and the CD85j Immune Receptor
Authors: Occhino Marzia , Ghiotto Fabio , Soro Simonetta , Mortarino Mimosa , Bosi Stefania , Maffei Massimo , Bruno Silvia , Nardini Marco , Figini Mariangela , Tramontano Anna , Ciccone Ermanno 
Published: April 2014

Abstract
UL18 is a glycoprotein encoded by the human cytomegalovirus genome and is thought to play a pivotal role during human cytomegalovirus infection, although its exact function is still a matter of debate. UL18 shares structural similarity with MHC class I and binds the receptor CD85j on immune cells. Besides UL18, CD85j binds MHC class I molecules. The binding properties of CD85j to MHC class I molecules have been thoroughly studied. Conversely, very little information is available on the CD85j/UL18 complex, namely that UL18 binds CD85j through its α3 domain with an affinity that is ∼1000-fold higher than the MHC class I affinity for CD85j. Deeper knowledge of features of the UL18/CD85j complex would help to disclose the function of UL18 when it binds to CD85j. In this study we first demonstrated that the UL18α3 domain is not sufficient per se for binding and that β2-microglobulin is necessary for UL18–CD85j interaction. We then dissected structural determinants of binding UL18 to CD85j. To this end, we constructed a three-dimensional model of the complex. The model was used to design mutants in selected regions of the putative interaction interface, the effects of which were measured on binding. Six regions in both the α2 and α3 domains and specific amino acids within them were identified that are potentially involved in the UL18–CD85j interaction. The higher affinity of UL18 to CD85j, compared with MHC class I, seems to be due not to additional interaction regions but to an overall better fit of the two molecules.
Human Cytomegalovirus Regulates Surface Expression of the Viral Protein UL18 by Means of Two Motifs Present in the Cytoplasmic Tail
Authors: Maffei Massimo , Ghiotto Fabio , Occhino Marzia , Bono Maria , De Santanna Amleto , Battini Lorenzo , Gusella G. Luca , Fais Franco , Bruno Silvia , Ciccone Ermanno 
Published: April 2014

Abstract
UL18 is a trans-membrane viral protein expressed on human cytomegalovirus (HCMV)-infected cells, and its surface expression determines the interaction of infected cells with lymphocytes expressing the CD85j (LIR-1/ILT2) receptor. We previously showed that the UL18–CD85j interaction elicits activation of T lymphocytes. However, in in vitro cell models UL18 displays mostly undetectable surface expression. Thus, we asked how surface expression of UL18 is regulated. Domain-swapping experiments and construction of specific mutants demonstrated that two motifs on its cytoplasmic tail, homologous to YXXΦ and KKXX consensus sequences, respectively, are responsible for impairing UL18 surface expression. However, the presence of the whole HCMV genome, granted by HCMV infection of human fibroblasts, restored surface expression of either UL18 or chimeric proteins carrying the UL18 cytoplasmic tail, starting from the third day after infection. It is of note that the two motifs responsible for cytoplasmic retention are identical in all 17 HCMV strains examined. We disclosed a control mechanism used by the HCMV to regulate the availability of UL18 on the infected-cell surface to allow interaction with its ligand on T and NK cells.
Regulation of CD1a Surface Expression and Antigen Presentation by Invariant Chain and Lipid Rafts
Authors: Sloma Ivan , Zilber Marie-Thérèse , Vasselon Thierry , Setterblad Niclas , Cavallari Marco , Mori Lucia , De Libero Gennaro , Charron Dominique , Mooney Nuala , Gelin Catherine 
Published: April 2014

Abstract
In immature dendritic cells (DCs), CD1a is almost exclusively expressed at the cell surface and its membrane organization is poorly understood. In this study, we report that MHC class II, invariant chain (Ii), and CD9 molecules are coimmunoprecipitated with CD1a in immature DCs, and that CD1a/Ii colocalization is dependent on lipid raft integrity. In HeLa-CIITA cells CD1a expression leads to increased Ii trafficking to the cell surface, confirming the relevance of this association. Furthermore, silencing of Ii in DCs induces significant CD1a accumulation on the plasma membrane whereas the total CD1a expression remains similar to that of control cells. These data suggest that CD1a recycling is facilitated by the association with the Ii. The CD1a localization in lipid rafts has functional relevance as demonstrated by inhibition of CD1a-restricted presentation following raft disruption. Overall, these findings identify Ii and lipid rafts as key regulators of CD1a organization on the surface of immature DCs and of its immunological function as Ag-presenting molecule.
Effector CD8 T Cell Development: A Balancing Act between Memory Cell Potential and Terminal Differentiation
Authors: Joshi Nikhil S. , Kaech Susan M. 
Published: April 2014

AbstractImmune responses to infection are optimally designed to generate large numbers of effector T cells while simultaneously minimizing the collateral damage of their potentially lethal actions and generating memory T cells to protect against subsequent encounter with pathogens. Much remains to be discovered about how these equally essential processes are balanced to enhance health and longevity and, more specifically, what factors control effector T cell expansion, differentiation, and memory cell formation. The innate immune system plays a prominent role in the delicate balance of these decisions. Insights into these questions from recent work in the area of effector CD8 T cell differentiation will be discussed.
Fast Progression of Recombinant Human Myelin/Oligodendrocyte Glycoprotein (MOG)-Induced Experimental Autoimmune Encephalomyelitis in Marmosets Is Associated with the Activation of MOG34–56-Specific Cytotoxic T Cells
Authors: Kap Yolanda S. , Smith Paul , Jagessar S. Anwar , Remarque Ed , Blezer Erwin , Strijkers Gustav J. , Laman Jon D. , Hintzen Rogier Q. , Bauer Jan , Brok Herbert P. M. , ‘t Hart Bert A. 
Published: April 2014

Abstract
The recombinant human (rh) myelin/oligodendrocyte glycoprotein (MOG)-induced experimental autoimmune encephalomyelitis (EAE) model in the common marmoset is characterized by 100% disease incidence, a chronic disease course, and a variable time interval between immunization and neurological impairment. We investigated whether monkeys with fast and slow disease progression display different anti-MOG T or B cell responses and analyzed the underlying pathogenic mechanism(s). The results show that fast progressor monkeys display a significantly wider specificity diversification of anti-MOG T cells at necropsy than slow progressors, especially against MOG34–56 and MOG74–96. MOG34–56 emerged as a critical encephalitogenic peptide, inducing severe neurological disease and multiple lesions with inflammation, demyelination, and axonal injury in the CNS. Although EAE was not observed in MOG74–96-immunized monkeys, weak T cell responses against MOG34–56 and low grade CNS pathology were detected. When these cases received a booster immunization with MOG34–56 in IFA, full-blown EAE developed. MOG34–56-reactive T cells expressed CD3, CD4, or CD8 and CD56, but not CD16. Moreover, MOG34–56-specific T cell lines displayed specific cytotoxic activity against peptide-pulsed B cell lines. The phenotype and cytotoxic activity suggest that these cells are NK-CTL. These results support the concept that cytotoxic cells may play a role in the pathogenesis of multiple sclerosis.
In Vivo Polarization of IFN-γ at Kupfer and Non-Kupfer Immunological Synapses during the Clearance of Virally Infected Brain Cells
Authors: Barcia Carlos , Wawrowsky Kolja , Barrett Robert J. , Liu Chunyan , Castro Maria G. , Lowenstein Pedro R. 
Published: April 2014

Abstract
Kupfer-type immunological synapses are thought to mediate intercellular communication between antiviral T cells and virally infected target Ag-presenting brain cells in vivo during an antiviral brain immune response. This hypothesis predicts that formation of Kupfer-type immunological synapses is necessary for polarized distribution of effector molecules, and their directed secretion toward the target cells. However, no studies have been published testing the hypothesis that cytokines can only form polarized clusters at Kupfer-type immunological synapses. Here, we show that IFN-γ and granzyme-B cluster in a polarized fashion at contacts between T cells and infected astrocytes in vivo. In some cases these clusters were found in Kupfer-type immunological synapses between T cells and infected astrocytes, but we also detected polarized IFN-γ at synaptic immunological contacts which did not form Kupfer-type immunological synaptic junctions, i.e., in the absence of polarization of TCR or LFA-1. This indicates that TCR signaling, which leads to the production, polarization, and eventual directed secretion of effector molecules such as IFN-γ, occurs following the formation of both Kupfer-type and non-Kupfer type immunological synaptic junctions between T cells and virally infected target astrocytes in vivo.
Cross Presentation of Antigen on MHC Class II via the Draining Lymph Node after Corneal Transplantation in Mice
Authors: Kuffová Lucia , Netuková Magdaléna , Duncan Linda , Porter Andrew , Stockinger Brigitta , Forrester John V. 
Published: April 2014

Abstract
We investigated Ag trafficking from the cornea and T effector cell activation in secondary lymphoid tissue after corneal transplantation. In preliminary experiments, the central cornea was shown to contain a population of CD45+, CD11b+, CD11c- cells, with a few MHC class II+ cells, and F4/80+ cells. However, MHC class II+ passenger leukocytes in donor cornea after allografting did not traffic to the draining lymph node. Instead, Ag (plasmid) delivered to the eye via the donor cornea during allograft was detected in host CD11c+ and F4/80+ APC in the draining lymph nodes and spleen. The earliest detection of APC-associated Ag was at 6 h in the draining lymph node and 24 h in the spleen. After 48 h Ag was not detected in the draining lymph node but was still present in the spleen. Ag applied to the donor corneal epithelium before allografting induced Ag-specific T cell activation and expansion in the draining lymph node with a peak response at 4–6 days, indicating that cross-presentation of Ag had occurred. We conclude therefore, that Ag is transported from the donor cornea within host APC and that this event occurs within hours after grafting. Ag is cross-presented to host CD4+ T cells on MHC class II and leads to the activation of Ag-specific effector T cells and clonal expansion in the draining lymph node.
Helper B Cells Promote Cytotoxic T Cell Survival and Proliferation Independently of Antigen Presentation through CD27/CD70 Interactions
Authors: Deola Sara , Panelli Monica C. , Maric Dragan , Selleri Silvia , Dmitrieva Natalia I. , Voss Ching Y. , Klein Harvey , Stroncek David , Wang Ena , Marincola Francesco M. 
Published: April 2014

Abstract
CD8-expressing cytotoxic T cell (CTL) interactions with APCs and helper T cells determine their function and ability to survive. In this study, we describe a novel interaction independent of Ag presentation between activated CTLs and bystander CD19-expressing B lymphocytes. Ag-stimulated CTLs serially engage autologous B lymphocytes through CD27/CD70 contact that promotes their survival and proliferation. Moreover, these interactions induce the release of proinflammatory cytokines that follows two general patterns: 1) an epitope-dependent enhancement of cytokine release, and 2) a previously undiscovered coordinate release of cytokines independent of epitope exposure. The latter includes chemoattractants targeting activated T cells. As a result, activated T cells are attracted to B cells, which exert a “helper” role in lymphatic organs or in areas of inflammation. This observation provides a mechanistic explanation to previously reported experimental observations suggesting that B cells are required for T cell priming in vivo.
Stimulation by TLR5 Modulates Osteoclast Differentiation through STAT1/IFN-β
Authors: Ha Hyunil , Lee Jong-Ho , Kim Ha-Neui , Kwak Han Bok , Kim Hyun-Man , Lee Shee Eun , Rhee Joon Haeng , Kim Hong-Hee , Lee Zang Hee 
Published: April 2014

Abstract
Osteoclasts are bone-resorbing cells that are differentiated from hemopoietic precursors of the monocyte-macrophage lineage. Stimulation of TLRs has been shown to positively or negatively modulate osteoclast differentiation, depending on the experimental condition. However, the molecular mechanism by which this modulation takes place remains unclear. In the present study, we examined the effects of flagellin, a specific microbial ligand of TLR5, on the receptor activator of NF-κB ligand (RANKL)-stimulated osteoclastogenesis. Flagellin suppressed RANKL induction of c-Fos protein expression in bone marrow-derived macrophages without affecting c-Fos mRNA expression. Ectopic overexpression of c-Fos and a constitutively active form of NFATc1 reversed the flagellin-induced anti-osteoclastogenic effect. The inhibitory effect of flagellin was mediated by IFN-β production. Flagellin stimulated IFN-β expression and release in bone marrow-derived macrophages, and IFN-β-neutralizing Ab prevented the flagellin-induced c-Fos down-regulation and the anti-osteoclastogenic effect. IFN-β gene induction by flagellin, LPS, or RANKL was dependent on STAT1 activation. Treatment with flagellin or RANKL stimulated STAT1 activation, and STAT1 deficiency or the JAK2 inhibitor AG490 dramatically prevented IFN-β induction in response to flagellin or RANKL. In addition, STAT1 deficiency abolished the anti-osteoclastogenic effect induced by flagellin or LPS. In contrast, flagellin stimulated osteoclast differentiation in cocultures of osteoblasts and bone marrow cells without inducing IFN-β. Thus, IFN-β acts as a critical modulator of osteoclastogenesis in response to TLR5 activation.
Human Follicular Dendritic Cells Interact with T Cells via Expression and Regulation of Cyclooxygenases and Prostaglandin E and I Synthases
Authors: Lee In Yong , Cho Whajung , Kim Jini , Park Chan-Sik , Choe Jongseon 
Published: April 2014

Abstract
PGE2 inhibits mature T cell proliferation and protects T cells from activation-induced cell death (AICD). We have previously demonstrated that human follicular dendritic cells (FDC) strongly express PGI synthase. In this study, the hypothesis that FDC have regulatory roles on germinal center T cells by controlling production of PGE2 and PGI2 was tested. Confocal microscopic analyses of human tonsil tissues revealed that FDC indeed expressed PGE synthase in addition to PGIS. To confirm these results, we studied the regulation mechanism of PG production in FDC, using an established human FDC-like cell line, HK. Specifically in response to TNF-α, TGF-β, and LPS, protein expression of cyclooxygenase (COX)-2 and downstream PGE synthase was up-regulated with coordinate kinetics, whereas COX-1 and PGIS were constitutively expressed. The increase of these enzymes was reflected in actual production of PGE2 and PGI2. Interestingly, IL-4 almost completely abrogated the stimulatory activity of TNF-α, TGF-β, and LPS in PG production. Furthermore, the up-regulation of PGE2 and PGI2 production was markedly down-regulated by indomethacin and a selective COX-2 inhibitor. PGI2 analog and PGE2 inhibited proliferation and AICD of T cells in dose- and time-dependent manners. Finally, coculture experiments revealed that HK cells indeed inhibit proliferation and AICD of T cells. Put together, these results show an unrecognized pathway of FDC and T cell interactions and differential mechanisms for PGE2 and PGI2 production, suggesting an important implication for development and use of anti-inflammatory drugs.
Mathematical Modeling Reveals the Biological Program Regulating Lymphopenia-Induced Proliferation
Authors: Yates Andrew , Saini Manoj , Mathiot Anne , Seddon Benedict 
Published: April 2014

Abstract
Recognition of peptide-MHC by the TCR induces T lymphocytes to undergo cell division. Although recognition of foreign peptide induces a program of cellular division and differentiation by responding T cells, stimulation by self-peptide MHC complexes in lymphopenic conditions induces a slower burst of divisions that may or may not be accompanied by effector differentiation. Although both responses are triggered by signals from the TCR, it is not known whether they represent distinct programs of cell cycle control. In this study, we use a mathematical modeling approach to analyze the proliferative response of TCR transgenic F5 T cells to lymphopenia. We tested two fundamentally different models of cell division: one in which T cells are triggered into an “autopilot” deterministic burst of divisions, a model successfully used elsewhere to describe T cell responses to cognate Ag, and a second contrasting model in which cells undergo independent single stochastic divisions. Whereas the autopilot model provided a very poor description of the F5 T cell responses to lymphopenia, the model of single stochastic divisions fitted the experimental data remarkably closely. Furthermore, this model proved robust because specific predictions of cellular behavior made by this model concerning the onset, rate, and nature of division were successfully validated experimentally. Our results suggest cell division induced by lymphopenia involves a process of single stochastic divisions, which is best suited to a homeostatic rather than differentiation role.
17β-Estradiol Alters the Activity of Conventional and IFN-Producing Killer Dendritic Cells
Authors: Siracusa Mark C. , Overstreet Michael G. , Housseau Franck , Scott Alan L. , Klein Sabra L. 
Published: April 2014

Abstract
Estrogens increase aspects of innate immunity and contribute to sex differences in the prevalence of autoimmune diseases and in response to infection. The goal of the present study was to assess whether exposure to 17β-estradiol (E2) affects the development and function of bone marrow-derived dendritic cells and to determine whether similar changes are observed in CD11c+ splenocytes exposed to E2 in vivo. E2 facilitated the differentiation of BM precursor cells into functional CD11c+CD11b+MHC class II+ dendritic cells (DCs) with increased expression of the costimulatory molecules CD40 and CD86. Exposure of bone marrow-derived dendritic cells to E2 also enhanced production of IL-12 in response to the TLR ligands, CpG and LPS. In contrast, CD11c+ cells isolated from the spleens of female C57BL/6 mice that were intact, ovariectomized, or ovariectomized with E2 replacement exhibited no differences in the number or activity of CD11c+CD11b+MHC class II+ DCs. The presence of E2 in vivo, however, increased the number of CD11c+CD49b+NK1.1low cells and reduced numbers of CD11c+CD49b+NK1.1high cells, a surface phenotype for IFN-producing killer DCs (IKDCs). Ultrastructural analysis demonstrated that CD11c+NK1.1+ populations were comprised of cells that had the appearance of both DCs and IKDCs. CD11c+ splenocytes isolated from animals with supplemental E2 produced more IFN-γ in response to IL-12 and IL-18. These data illustrate that E2 has differential effects on the development and function of DCs and IKDCs and provide evidence that E2 may strengthen innate immunity by enhancing IFN-γ production by CD11c+ cells.
The Ontogeny and Fate of NK Cells Marked by Permanent DNA Rearrangements
Authors: Pilbeam Kristy , Basse Per , Brossay Laurent , Vujanovic Nikola , Gerstein Rachel , Vallejo Abbe N. , Borghesi Lisa 
Published: April 2014

Abstract
A subset of NK cells bears incomplete V(D)J rearrangements, but neither the consequence to cell activities nor the precise developmental stages in which recombination occurs is known. These are important issues, as recombination errors cause cancers of the B and T lineages. Using transgenic recombination reporter mice to examine NK cell dynamics in vivo, we show that recombination+ NK cells have distinct developmental patterns in the BM, including reduced homeostatic proliferation and diminished Stat5 phosphorylation. In the periphery, both recombination+ and recombination− NK cells mediate robust functional responses including IFN-γ production, cytolysis, and tumor homing, suggesting that NK cells with distinct developmental histories can be found together in the periphery. We also show that V(D)J rearrangement marks both human cytolytic (CD56dim) and immunoregulatory (CD56bright) populations, demonstrating the distribution of permanent DNA rearrangements across major NK cell subsets in man. Finally, direct quantification of rag transcripts throughout NK cell differentiation in both mouse and man establishes the specific developmental stages that are susceptible to V(D)J rearrangement. Together, these data demonstrate that multipotent progenitors rather than lineage-specified NK progenitors are targets of V(D)J recombination and that NK cells bearing the relics of earlier V(D)J rearrangements have different developmental dynamics but robust biological capabilities in vivo.
Th17 Cells Exhibit a Distinct Calcium Profile from Th1 and Th2 Cells and Have Th1-Like Motility and NF-AT Nuclear Localization
Authors: Weber K. Scott , Miller Mark J. , Allen Paul M. 
Published: April 2014

Abstract
Helper T cell subsets have evolved to respond to different pathogens, and upon activation secrete distinct sets of cytokines. The discovery and identification of Th17 cells, which develop via a unique lineage from Th1 and Th2 cells, have provided new insights into aspects of immune regulation and host defense that were previously unclear. A key early signaling event upon Ag recognition is elevation of intracellular free Ca2+, and cytokine expression can be differentially induced depending on the duration, amplitude, and pattern of Ca2+ signaling. Th1 and Th2 cells can be distinguished by their Ca2+ profiles, and we provide in this study the first report regarding Ca2+ signaling in Th17 cells. Th17 cells have a distinct Ca2+ signaling profile from Th1 and Th2 cells with intermediate sustained Ca2+ levels and increased oscillations compared with Th2 cells. Elevated intracellular Ca2+ has been shown to inhibit T cell motility, and we observed that Th17 cells, like Th1 cells, are less motile than Th2 cells. Analysis of NF-AT nuclear localization revealed that Th1 and Th17 cells have significantly higher levels at later time points compared with Th2 cells. Thus, these findings show that Th17 cells, in addition to their distinct cytokine response from Th1 and Th2 cells, display unique patterns of intracellular Ca2+ signaling and Th1-like motility behavior and nuclear localization of NF-AT.