bluuebunny/crossref_metadata_2025_split huggingface dataset:
Protein Kinase C (PKC)α and PKCθ Are the Major PKC Isotypes Involved in TCR Down-Regulation
Authors: von Essen Marina , Nielsen Martin W. , Bonefeld Charlotte M. , Boding Lasse , Larsen Jeppe M. , Leitges Michael , Baier Gottfried , Ødum Niels , Geisler Carsten 
Published: April 2014

AbstractIt is well known that protein kinase C (PKC) plays an important role in regulation of TCR cell surface expression levels. However, eight different PKC isotypes are present in T cells, and to date the particular isotype(s) involved in TCR down-regulation remains to be identified. The aim of this study was to identify the PKC isotype(s) involved in TCR down-regulation and to elucidate the mechanism by which they induce TCR down-regulation. To accomplish this, we studied TCR down-regulation in the human T cell line Jurkat, in primary human T cells, or in the mouse T cell line DO11.10 in which we either overexpressed constitutive active or dominant-negative forms of various PKC isotypes. In addition, we studied TCR down-regulation in PKC knockout mice and by using small interfering RNA-mediated knockdown of specific PKC isotypes. We found that PKCα and PKCθ were the only PKC isotypes able to induce significant TCR down-regulation. Both isotypes mediated TCR down-regulation via the TCR recycling pathway that strictly depends on Ser126 and the di-leucine-based receptor-sorting motif of the CD3γ chain. Finally, we found that PKCθ was mainly implicated in down-regulation of directly engaged TCR, whereas PKCα was involved in down-regulation of nonengaged TCR.
TLR9 Is Required for the Gut-Associated Lymphoid Tissue Response following Oral Infection of Toxoplasma gondii
Authors: Minns Laurie A. , Menard Laurence C. , Foureau David M. , Darche Sylvie , Ronet Catherine , Mielcarz Daniel W. , Buzoni-Gatel Dominique , Kasper Lloyd H. 
Published: April 2014

Abstract
TLRs expressed by a variety of cells, including epithelial cells, B cells, and dendritic cells, are important initiators of the immune response following stimulation with various microbial products. Several of the TLRs require the adaptor protein, MyD88, which is an important mediator for the immune response following Toxoplasma gondii infection. Previously, TLR9-mediated innate immune responses were predominantly associated with ligation of unmethylated bacterial CpG DNA. In this study, we show that TLR9 is required for the Th1-type inflammatory response that ensues following oral infection with T. gondii. After oral infection with T. gondii, susceptible wild-type (WT; C57BL/6) but not TLR9−/− (B6 background) mice develop a Th1-dependent acute lethal ileitis; TLR9−/− mice have higher parasite burdens than control WT mice, consistent with depressed IFN-γ-dependent parasite killing. A reduction in the total T cell and IFN-γ-producing T cell frequencies was observed in the lamina propria of the TLR9−/− parasite-infected mice. TLR9 and type I IFN production was observed by cells from infected intestines in WT mice. TLR9 expression by dendritic cell populations is essential for their expansion in the mesenteric lymph nodes of infected mice. Infection of chimeric mice deleted of TLR9 in either the hemopoietic or nonhemopoietic compartments demonstrated that TLR9 expression by cells from both compartments is important for efficient T cell responses to oral infection. These observations demonstrate that TLR9 mediates the innate response to oral parasite infection and is involved in the development of an effective Th1-type immune response.
Class IA Phosphatidylinositide 3-Kinases, rather than p110γ, Regulate Formyl-Methionyl-Leucyl-Phenylalanine-Stimulated Chemotaxis and Superoxide Production in Differentiated Neutrophil-Like PLB-985 Cells
Authors: Boulven Isaline , Levasseur Sylvain , Marois Sébastien , Paré Guillaume , Rollet-Labelle Emmanuelle , Naccache Paul H. 
Published: April 2014

Abstract
Class I PI3Ks, through the formation of phosphatidylinositol-3,4,5-trisphosphate (PI(3,4,5)P3), are thought of as essential elements of the neutrophil response to chemotactic factors. Moreover, the recent development of PI3K-deficient mice and isoform-specific inhibitors enabled examinations of the contribution of the distinct PI3K isoforms in neutrophil activation. However, the results of these various studies are conflicting, and the exact role of the different PI3K isoforms is not yet clearly established, particularly in human cells. In the present study, we used a different approach to assess the role of the distinct PI3K isoforms in response to the chemotactic agent fMLP. We inhibited PI3K activities by the transient expression following nucleofection of dominant negative mutants of either p85α or p110γ in the human myeloid cell line PLB-985, which can be induced to express a neutrophil-like phenotype. The data obtained with this approach showed that the production of PI(3,4,5)P3 triggered by fMLP is biphasic, with a peak of production observed in a short time period that entirely depends on p110γ activity, and a delayed phase that is mediated by class IA PI3K. We also provide evidence that the PI3K-dependent functional responses (i.e., superoxide production and chemotaxis) induced by the chemotactic factor mainly involve PI3K IA and, by implication, the delayed phase of PI(3,4,5)P3 production, whereas p110γ and the early peak of PI(3,4,5)P3 do not play major roles in the initiation or the control of these responses.
Timely DNA Vaccine Combined with Systemic IL-12 Prevents Parotid Carcinomas before a Dominant-Negative p53 Makes Their Growth Independent ofHER-2/neuExpression
Authors: Pannellini Tania , Spadaro Michela , Di Carlo Emma , Ambrosino Elena , Iezzi Manuela , Amici Augusto , Lollini Pier Luigi , Forni Guido , Cavallo Federica , Musiani Piero 
Published: April 2014

AbstractDouble transgenic mice overexpressing the transforming rat HER-2/neu oncogene and the mutated p53, with both dominant-negative and a gain-of-function properties, display early aggressive and metastasizing parotid tumors. Multiple acinar and ductal hyperplasia foci overexpressing the HER-2/neu gene product are evident at wk 5 and progress to poorly differentiated carcinoma by wk 7. Mice die before wk 18 with invasive carcinomas and multiple metastases that no longer express HER-2/neu. A combination of repeated electroporations of plasmids coding for the extracellular and transmembrane domains of the rat HER-2/neu receptor with systemic IL-12 administrations started when the parotids that present diffuse hyperplasia protected all female and 50% of the male mice until the close of the experiment at wk 40. This combined treatment began when multifocal in situ carcinomas that were already present cured 33% of the females and 25% of the males. The most prominent immunologic features associated with the antitumor protection were the production of high titers of anti-HER-2/neu Abs and the nonappearance of cell-mediated cytotoxic reactivity. In conclusion, anti-HER-2/neu vaccination combined with systemic IL-12 control parotid carcinomas as far as p53 mutation makes their growth independent of HER-2/neu expression.
Leptin Receptor Expression and Signaling in Lymphocytes: Kinetics During Lymphocyte Activation, Role in Lymphocyte Survival, and Response to High Fat Diet in Mice
Authors: Papathanassoglou Elizabeth , El-Haschimi Karim , Li Xian Chang , Matarese Giuseppe , Strom Terry , Mantzoros Christos 
Published: April 2014

Abstract
Leptin has direct effects not only on neuroendocrine function and metabolism, but also on T cell-mediated immunity. We report in this study that leptin receptor (ObR) is expressed on resting normal mouse CD4+, CD8+, B cells, and monocyte/macrophages. ObR expression is up-regulated following cell activation, but with different kinetics, in different lymphocyte subsets. Leptin binding to ObR results in increased STAT-3 activation in T cells, with a different activation pattern in resting vs anti-CD3 Ab stimulated T cells. Leptin also promotes lymphocyte survival in vitro by suppressing Fas-mediated apoptosis. B lymphocytes appear to be more susceptible to the antiapoptotic effects of leptin, and they show higher surface expression of ObR, compared with T cells. Moreover, CD4+ T cells isolated from ObR-deficient mice displayed a reduced proliferative response, compared with normal controls. Furthermore, ObR/STAT-3-mediated signaling in T lymphocytes is decreased in the diet-induced obese mouse model of obesity and leptin resistance. In summary, our findings show that the ObR is expressed on normal mouse lymphocyte subsets, that leptin plays a role in lymphocyte survival, and that leptin alters the ObR/STAT-3-mediated signaling in T cells. Taken together, our data further support the notion that nutritional status acting via leptin-dependent mechanisms may alter the nature and vigor of the immune response.
Indexation as a Novel Mechanism of Lymphocyte Homeostasis: The Number of CD4+CD25+ Regulatory T Cells Is Indexed to the Number of IL-2-Producing Cells
Authors: Almeida Afonso R. M. , Zaragoza Bruno , Freitas Antonio A. 
Published: April 2014

Abstract
To fulfill its mission, the immune system must maintain a complete set of different cellular subpopulations that play specific roles in immune responses. We have investigated the mechanisms regulating CD4+CD25+ regulatory T (Treg) cell homeostasis. We show that the expression of the high-affinity IL-2Rα endows these cells with the capacity to explore the IL-2 resource, ensuring their presence while keeping their number tied to the number of CD4+ T cells that produce IL-2. We show that such a homeostatic mechanism allows the increased expansion of T cells without causing disease. The indexing of Treg cells to the number of activated IL-2-producing cells may constitute a feedback mechanism that controls T cell expansion during immune responses, thus preventing autoimmune or lymphoproliferative diseases. The present study highlights that maintenance of proportions between different lymphocyte subsets may also be critical for the immune system and are under strict homeostatic control.
Galectin-1-Matured Human Monocyte-Derived Dendritic Cells Have Enhanced Migration through Extracellular Matrix
Authors: Fulcher Jennifer A. , Hashimi Sara T. , Levroney Ernest L. , Pang Mabel , Gurney Kevin B. , Baum Linda G. , Lee Benhur 
Published: April 2014

AbstractDendritic cells (DCs) are potent mediators of the immune response, and can be activated by exogenous pathogen components. Galectin-1 is a member of the conserved β-galactoside-binding lectin family that binds galactoside residues on cell surface glycoconjugates. Galectin-1 is known to play a role in immune regulation via action on multiple immune cells. However, its effects on human DCs are unknown. In this study, we show that galectin-1 induces a phenotypic and functional maturation in human monocyte-derived DCs (MDDCs) similar to but distinct from the activity of the exogenous pathogen stimuli, LPS. Immature human MDDCs exposed to galectin-1 up-regulated cell surface markers characteristic of DC maturation (CD40, CD83, CD86, and HLA-DR), secreted high levels of IL-6 and TNF-α, stimulated T cell proliferation, and showed reduced endocytic capacity, similar to LPS-matured MDDCs. However, unlike LPS-matured DCs, galectin-1-treated MDDCs did not produce the Th1-polarizing cytokine IL-12. Microarray analysis revealed that in addition to modulating many of the same DC maturation genes as LPS, galectin-1 also uniquely up-regulated a significant subset of genes related to cell migration through the extracellular matrix (ECM). Indeed, compared with LPS, galectin-1-treated human MDDCs exhibited significantly better chemotactic migration through Matrigel, an in vitro ECM model. Our findings show that galectin-1 is a novel endogenous activator of human MDDCs that up-regulates a significant subset of genes distinct from those regulated by a model exogenous stimulus (LPS). One unique effect of galectin-1 is to increase DC migration through the ECM, suggesting that galectin-1 may be an important component in initiating an immune response.
FOXP3+CD4+CD25+ Adaptive Regulatory T Cells Express Cyclooxygenase-2 and Suppress Effector T Cells by a Prostaglandin E2-Dependent Mechanism
Authors: Mahic Milada , Yaqub Sheraz , Johansson C. Christian , Taskén Kjetil , Aandahl Einar M. 
Published: April 2014

Abstract
CD4+CD25+ regulatory T (TR) cells suppress effector T cells by partly unknown mechanisms. In this study, we describe a population of human suppressive CD4+CD25+ adaptive TR (TRadapt) cells induced in vitro that express cyclooxygenase 2 (COX-2) and the transcription factor FOXP3. TRadapt cells produce PGE2 and suppress effector T cell responses in a manner that is reversed by COX inhibitors and PGE2 receptor-specific antagonists. In resting CD4+CD25− T cells, treatment with PGE2 induced FOXP3 expression. Thus, autocrine and paracrine effects of PGE2 produced by COX-2-positive TRadapt cells may be responsible for both the FOXP3+ phenotype and the mechanism used by these cells to suppress effector T cells.
Lymphotoxin Pathway-Directed, Autoimmune Regulator-Independent Central Tolerance to Arthritogenic Collagen
Authors: Chin Robert K. , Zhu Mingzhao , Christiansen Peter A. , Liu Wenhua , Ware Carl , Peltonen Leena , Zhang Xuejun , Guo Linjie , Han Shuhua , Zheng Biao , Fu Yang-Xin 
Published: April 2014

Abstract
Ectopic expression of peripherally restricted Ags by medullary thymic epithelial cells (mTECs) is associated with negative selection. Autoimmune regulator (AIRE) is considered to be the master regulator of these Ags. We show in this study that the ectopic expression of type II collagen (CII) in mTECs and the corresponding central tolerance to CII are AIRE independent but lymphotoxin dependent. The failure to properly express CII in mTECs of Lta−/− and Ltbr−/− mice leads to overt autoimmunity to CII and exquisite susceptibility to arthritis. These findings define the existence of additional pathways of ectopic peripheral Ag expression, parallel to and independent of AIRE, which may cover an extended spectrum of peripheral Ags in the thymus.
Cutting Edge: Interleukin 17 Signals through a Heteromeric Receptor Complex
Authors: Toy Dean , Kugler David , Wolfson Martin , Bos Tim Vanden , Gurgel Jesse , Derry Jonathan , Tocker Joel , Peschon Jacques 
Published: April 2014

AbstractIL-17 is an inflammatory cytokine produced primarily by a unique lineage of CD4 T cells that plays critical roles in the pathogenesis of multiple autoimmune diseases. IL-17RA is a ubiquitously expressed receptor that is essential for IL-17 biologic activity. Despite widespread receptor expression, the activity of IL-17 is most classically defined by its ability to induce the expression of inflammatory cytokines, chemokines, and other mediators by stromal cells. The lack of IL-17 responsiveness in mouse stromal cells genetically deficient in IL-17RA is poorly complemented by human IL-17RA, suggesting the presence of an obligate ancillary component whose activity is species specific. This component is IL-17RC, a distinct member of the IL-17R family. Thus, the biologic activity of IL-17 is dependent on a complex composed of IL-17RA and IL-17RC, suggesting a new paradigm for understanding the interactions between the expanded family of IL-17 ligands and their receptors.
Signal Regulatory Protein Molecules Are Differentially Expressed by CD8− Dendritic Cells
Authors: Lahoud Mireille H. , Proietto Anna I. , Gartlan Kate H. , Kitsoulis Susie , Curtis Joan , Wettenhall James , Sofi Mariam , Daunt Carmel , O’Keeffe Meredith , Caminschi Irina , Satterley Keith , Rizzitelli Alexandra , Schnorrer Petra , Hinohara Atsushi , Yamaguchi Yasunori , Wu Li , Smyth Gordon , Handman Emanuela , Shortman Ken , Wright Mark D. 
Published: April 2014

Abstract
A normalized subtracted gene expression library was generated from freshly isolated mouse dendritic cells (DC) of all subtypes, then used to construct cDNA microarrays. The gene expression profiles of the three splenic conventional DC (cDC) subsets were compared by microarray hybridization and two genes encoding signal regulatory protein β (Sirpβ1 and Sirpβ4) molecules were identified as differentially expressed in CD8− cDC. Genomic sequence analysis revealed a third Sirpβ member localized in the same gene cluster. These Sirpβ genes encode cell surface molecules containing extracellular Ig domains and short intracytoplasmic domains that have a charged amino acid in the transmembrane region which can potentially interact with ITAM-bearing molecules to mediate signaling. Indeed, we demonstrated interactions between Sirpβ1 and β2 with the ITAM-bearing signaling molecule Dap12. Real-time PCR analysis showed that all three Sirpβ genes were expressed by CD8− cDC, but not by CD8+ cDC or plasmacytoid pre-DC. The related Sirpα gene showed a similar expression profile on cDC subtypes but was also expressed by plasmacytoid pre-DC. The differential expression of Sirpα and Sirpβ1 molecules on DC was confirmed by staining with mAbs, including a new mAb recognizing Sirpβ1. Cross-linking of Sirpβ1 on DC resulted in a reduction in phagocytosis of Leishmania major parasites, but did not affect phagocytosis of latex beads, perhaps indicating that the regulation of phagocytosis by Sirpβ1 is a ligand-dependent interaction. Thus, we postulate that the differential expression of these molecules may confer the ability to regulate the phagocytosis of particular ligands to CD8− cDC.
A Role for DNA Hypomethylation and Histone Acetylation in Maintaining Allele-Specific Expression of Mouse NKG2A in Developing and Mature NK Cells
Authors: Rogers Sally L. , Rouhi Arefeh , Takei Fumio , Mager Dixie L. 
Published: April 2014

AbstractThe repertoire of receptors that is expressed by NK cells is critical for their ability to kill virally infected or transformed cells. However, the molecular mechanisms that determine whether and when NK receptor genes are transcribed during hemopoiesis remain unclear. In this study, we show that hypomethylation of a CpG-rich region in the mouse NKG2A gene is associated with transcription of NKG2A in ex vivo NK cells and NK cell lines. This observation was extended to various developmental stages of NK cells sorted from bone marrow, in which we demonstrate that the CpGs are methylated in the NKG2A-negative stages (hemopoietic stem cells, NK progenitors, and NKG2A-negative NK cells), and hypomethylated specifically in the NKG2A-positive NK cells. Furthermore, we provide evidence that DNA methylation is important in maintaining the allele-specific expression of NKG2A. Finally, we show that acetylated histones are associated with the CpG-rich region in NKG2A positive, but not negative, cell lines, and that treatment with the histone deacetylase inhibitor trichostatin A alone is sufficient to induce NKG2A expression. Treatment with the methyltransferase inhibitor 5-azacytidine only is insufficient to induce transcription, but cotreatment with both drugs resulted in a significantly greater induction, suggesting a cooperative role for DNA methylation and histone acetylation status in regulating gene expression. These results enhance our understanding of the formation and maintenance of NK receptor repertoires in developing and mature NK cells.
Haemophilus influenzae Surface Fibrils Contribute to Serum Resistance by Interacting with Vitronectin
Authors: Hallström Teresia , Trajkovska Elena , Forsgren Arne , Riesbeck Kristian 
Published: April 2014

Abstract
Vitronectin inhibits the membrane attack complex of the complement system and is found both in plasma and the extracellular matrix. In this study, we have identified the outer membrane protein Haemophilus surface fibrils (Hsf) as the major vitronectin-binding protein in encapsulated H. influenzae type b. A H. influenzae mutant devoid of Hsf showed a significantly decreased binding to both soluble and immobilized vitronectin as compared with the wild-type counterpart. Moreover, Escherichia coli-expressing Hsf at the surface strongly adhered to immobilized vitronectin. Importantly, the H. influenzae Hsf mutant had a markedly reduced survival as compared with the wild-type bacterium when incubated with normal human serum. A series of truncated Hsf fragments were recombinantly manufactured in E. coli. The vitronectin binding regions were located within two separate binding domains. In conclusion, Hsf interacts with vitronectin and thereby inhibits the complement-mediated bactericidal activity, and thus is a major H. influenzae virulence factor.
Altered CD4+ T Cell Phenotype and Function Determine the Susceptibility to Mucosal Candidiasis in Transgenic Mice Expressing HIV-1
Authors: Lewandowski Daniel , Marquis Miriam , Aumont Francine , Lussier-Morin Annie-Claude , Raymond Marianne , Sénéchal Serge , Hanna Zaher , Jolicoeur Paul , de Repentigny Louis 
Published: April 2014

Abstract
The impairments of protective mucosal immunity which cause susceptibility to oropharyngeal candidiasis (OPC) in HIV infection remain undefined. This study used a model of OPC in CD4C/HIV MutA transgenic (Tg) mice expressing Rev, Env, and Nef of HIV-1 to investigate the role of transgene expressing dendritic cells (DCs) and CD4+ T cells in maintenance of chronic oral carriage of Candida albicans. DCs were depleted in the Tg mice and had an immature phenotype, with low expression of MHC class II and IL-12. CD4+ T cells were quantitatively reduced in the oral mucosa, cervical lymph nodes (CLNs) and peripheral blood of the Tg mice, and displayed a polarization toward a nonprotective Th2 response. Proliferation of CLN CD4+ T cells from infected Tg mice in response to C. albicans Ag in vitro was abrogated and the cells failed to acquire an effector phenotype. Coculture of C. albicans-pulsed DCs with CD4+ T cells in vitro showed that Tg expression in either or both of these cell populations sharply reduced the proliferation of CD4+ T cells and their production of IL-2. Finally, transfer of naive non-Tg CD4+ T cells into these Tg mice restored proliferation to C. albicans Ag and sharply reduced oral burdens of C. albicans. Overall, these results indicate that defective CD4+ T cells primarily determine the susceptibility to chronic carriage of C. albicans in these Tg mice.
Evaluation of Immunological Paradigms in a Virus Model: Are Dendritic Cells Critical for Antiviral Immunity and Viral Clearance?
Authors: Ciavarra Richard P. , Stephens Amber , Nagy Sandra , Sekellick Margaret , Steel Christina 
Published: April 2014

AbstractWe have examined the role of dendritic cells (DCs) in the antiviral immune response and viral clearance using a transgenic mouse model (CD11c-diphtheria toxin (DT) receptor GFP) that allows for their conditional ablation in vivo. DT administration systemically ablated conventional and IFN-producing plasmacytoid DCs (pDCs) in transgenic, but not nontransgenic littermates, without elimination of splenic macrophages. Unexpectedly, early (12 and 48 h postinfection) viral clearance of vesicular stomatitis virus was normal in DC-depleted mice despite markedly reduced serum titers of type I IFN. DC-depleted mice remained virus-free with the exception of a subset (∼30%) that developed overwhelming and fatal brain infections 6 days postinfection. However, DT treatment profoundly inhibited clonal expansion of naive CD8+ vesicular stomatitis virus-specific T cells without altering the primary Th1 and Th2 cytokine response. Optimal clonal expansion required pDCs because selective elimination of these cells in vivo with a depleting Ab also suppressed expansion of tetramer+ cells, although Th1/Th2 cytokine production remained unaltered. Collectively, these data indicate that conventional DCs and to a lesser extent pDCs are critical for proliferation of naive antiviral T cells. However, other components of the primary adaptive immune response (Th1/Th2 cytokines) are essentially normal in the absence of DCs, which may account for the efficient viral clearance seen in DC-depleted mice. Thus, sufficient redundancy exists in the immune system to sustain efficient viral clearance despite loss of an APC considered essential for induction of a primary antiviral immune response.