bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cutting Edge: CD4 T Cell-Mast Cell Interactions Alter IgE Receptor Expression and Signaling
Authors: Kashyap Mohit , Thornton Angela M. , Norton Sarah Kennedy , Barnstein Brian , Macey Matthew , Brenzovich Jennifer , Shevach Ethan , Leonard Warren J. , Ryan John J. 
Published: April 2014

Abstract
Mast cell activation is associated with atopic and inflammatory diseases, but the natural controls of mast cell homeostasis are poorly understood. We hypothesized that CD4+CD25+ regulatory T cells (Treg) could function in mast cell homeostasis. In this study, we demonstrate that mast cells can recruit both Treg and conventional CD4+ T cells (Tconv). Furthermore, Treg, but not Tconv, suppress mast cell FcεRI expression. Despite the known inhibitory functions of IL-10 and TGFβ1, FcεRI suppression was independent of IL-10 and TGF-β1 and required cell contact. Surprisingly, coculture with either Treg or Tconv cells suppressed IgE-mediated leukotriene C4 production but enhanced cytokine production by mast cells. This was accompanied by a selective increase in FcεRI-mediated Stat5 phosphorylation, which is a critical mediator of IgE-mediated cytokine secretion. These data are the first direct demonstration that mast cells can recruit Treg and illustrate that T cell interactions can alter the mast cell response.
Antigen Controls IL-7Rα Expression Levels on CD8 T Cells during Full Activation or Tolerance Induction
Authors: Hammerbeck Christopher D. , Mescher Matthew F. 
Published: April 2014

Abstract
The high-affinity chain of the IL-7 receptor, IL-7Rα (CD127), is expressed by effector CD8 T cells that have the capacity to become memory cells. IL-7Rα expression is uniformly high on naive CD8 T cells, and the majority of these cells down-regulate expression upon antigenic challenge. At the peak of expansion, the fraction of effectors expressing high IL-7Rα varies depending on the response examined. The signals that a CD8 T cell receives during a response to Ag that lead to altered expression of IL-7Rα have not been fully defined. In vitro experiments demonstrated that Ag alone is sufficient to down-regulate IL-7Rα on all cells and most of the cells rapidly re-express the receptor upon removal from Ag. Expression was not altered by the B7.1 costimulatory ligand or when IL-12 was present to provide the signal needed for development of effector functions, indicating that TCR engagement is sufficient to regulate IL-7Rα expression. Consistent with this, in vivo priming with peptide Ag resulted in IL-7Rα expression that inversely correlated with Ag levels, and expression levels were not changed when IL-12 or adjuvant were administered with Ag. A large fraction of the cells present at the peak of expansion had re-expressed IL-7Rα, but most of these cells failed to survive; those that did survive expressed high IL-7Rα levels. Thus, Ag-dependent signals regulate IL-7Rα levels on responding CD8 T cells, and this occurs whether the responding cells become fully activated or are rendered tolerant by administration of peptide Ag alone.
TLR7 Is Involved in Sequence-Specific Sensing of Single-Stranded RNAs in Human Macrophages
Authors: Gantier Michael P. , Tong Stephen , Behlke Mark A. , Xu Dakang , Phipps Simon , Foster Paul S. , Williams Bryan R. G. 
Published: April 2014

Abstract
Human TLR7 and 8 (hTLR7/8) have been implicated in the sequence-dependent detection of RNA oligonucleotides in immune cells. Although hTLR7 sequence-specific sensing of short RNAs has been inferred from studies of murine TLR7, this has yet to be established for hTLR7. We found that different short ssRNA sequences selectively induced either TNF-α or IFN-α in human PBMCs. The sequence-specific TNF-α response to ssRNAs observed in PBMCs could be replicated in activated human macrophage-like (THP-1) cells pretreated with IFN-γ. Surprisingly, suppression of hTLR7 expression by RNA interference in this model reduced sensing of all immunostimulatory ssRNAs tested. Modulation of the relative expression ratio of hTLR7 to hTLR8 in THP-1 cells correlated with differential sensing of immunostimulatory sequences. Furthermore, the sequence-specific IFN-α induction profile in human PBMCs was accurately modeled by a sequence-specific activation of murine TLR7 in mouse macrophages. Thus, we demonstrate for the first time that hTLR7 is involved in sequence-specific sensing of ssRNAs. We establish a novel cell model for the prediction of TNF-α induction by short RNAs in human macrophages. Our results suggest that differential sequence-specific sensing of RNA oligonucleotides between human and mouse macrophages is due to the modulation of TLR7 sensing by human TLR8.
Characterization of the In Vivo Dynamics of Medullary CD4+CD8− Thymocyte Development
Authors: Jin Rong , Wang Wei , Yao Jin-Yan , Zhou Yu-Bin , Qian Xiao-Ping , Zhang Jun , Zhang Yu , Chen Wei-Feng 
Published: April 2014

Abstract
Our previous studies have defined a differentiation program followed by the newly generated single-positive (SP) thymocytes before their emigration to the periphery. In the present study, we further characterize the development of CD4SP cells in the thymic medulla using mainly intrathymic adoptive transfer assays. By analyzing the differentiation kinetics of the donor cells, which were shown to home correctly to the medullary region following adoptive transfer, we established the precursor–progeny relationship among the four subsets of CD4SP thymocytes (SP1–SP4) and demonstrated that the progression from SP1 to SP4 was unidirectional and largely synchronized. Notably, while the phenotypic maturation from SP1 to SP4 was achieved in 2–3 days, a small fraction of donor cells could be retained in the thymus for a longer period, during which they further matured in function. BrdU incorporation indicated that cell expansion occurred at multiple stages except SP1. Nevertheless, CFSE labeling revealed that only a limited number of cells actually divided during their stay in the medulla. As to the thymic emigration, there was a clear bias toward cells with increasing maturity, but no distinction was found between dividing and nondividing thymocytes. Collectively, these data not only provide solid evidence for a highly ordered differentiation program for CD4SP thymocytes, but they also illustrate several important features associated with the developmental process.
ICOS, CD40, and Lymphotoxin β Receptors Signal Sequentially and Interdependently to Initiate a Germinal Center Reaction
Authors: Vu Frances , Dianzani Umberto , Ware Carl F. , Mak Tak , Gommerman Jennifer L. 
Published: April 2014

Abstract
Germinal center (GC) responses to T-dependent Ags require effective collaboration between Th cells, activated B cells, and follicular dendritic cells within a highly organized microenvironment. Studies using gene-targeted mice have highlighted nonredundant molecules that are key for initiating and maintaining the GC niche, including the molecules of the ICOS, CD40, and lymphotoxin (LT) pathways. Signaling through ICOS has multiple consequences, including cytokine production, expression of CD40L on Th cells, and differentiation into CXCR5+ follicular Th cells, all of which are important in the GC reaction. We have therefore taken advantage of ICOS−/− mice to dissect which downstream elements are required to initiate the formation of GC. In the context of a T-dependent immune response, we found that GC B cells from ICOS−/− mice express lower levels of LTαβ compared with wild-type GC B cells in vivo, and stimulation of ICOS on T cells induces LTαβ on B cells in vitro. Administration of agonistic anti-LTβ receptor Ab was unable to restore the GC response in ICOS−/− mice, suggesting that additional input from another pathway is required for optimal GC generation. In contrast, treatment with agonistic anti-CD40 Ab in vivo recovered GC networks and restored LTαβ expression on GC B cells in ICOS−/− mice, and this effect was dependent on LTβ receptor signaling. Collectively, these data demonstrate that ICOS activation is a prerequisite for the up-regulation of LTαβ on GC B cells in vivo and provide a model for cooperation between ICOS, CD40, and LT pathways in the context of the GC response.
Porcine Reproductive and Respiratory Syndrome Virus Subverts Repertoire Development by Proliferation of Germline-Encoded B Cells of All Isotypes Bearing Hydrophobic Heavy Chain CDR3
Authors: Butler John E. , Wertz Nancy , Weber Patrick , Lager Kelly M. 
Published: April 2014

Abstract
Isolator piglets infected with porcine reproductive and respiratory syndrome virus (PRRSV), which is related to the lactate dehydrogenase-elevating virus of mice, develop severe hypergammaglobulinemia, lymph node adenopathy, and autoimmune disease. Many of the polyclonally activated B cell clones bear hydrophobic H chain CDR3s (HCDR3s) and are disseminated to most lymphoid tissues. We show in this study that B cells with identical hydrophobic HCDR3s are expressed with all major isotypes in PRRSV-infected piglets (PIPs), explaining why PRRSV-induced hypergammaglobulinemia is seen in all major isotypes. Up to one-third of randomly selected VDJ clones from the respiratory tract of PIPs have hydrophobic HCDR3s exclusively bearing VDJ rearrangements with CDR1, CDR2, and nearly intact DH segments in germline configuration. These HCDR3s are long and DHA and DHB are exclusively used in reading frame 3. A minimal tripeptide motif containing three hydrophobic amino acids (Leu, Val, and Ile) or any two plus alanine is common to this hydrophobic patch. We propose that PRRSV infection causes generalized Ag-independent B cell activation and hypergammaglobulinemia with biased expansion of a subpopulation of the preimmune repertoire with hydrophobic binding sites that normally disappears during Ag-driven repertoire diversification. Elevated Ig levels in PIP cannot be explained as antiviral Abs; some Igs can account for autoantibodies to dsDNA and Golgi, whereas those with hydrophobic binding sites may account for the Ig aggregates seen in PIPs and lactate dehydrogenase-elevating virus-infected mice. This diversion from normal repertoire development may explain the delayed immune response to PRRSV.
Cholesterol-Rich Membrane Rafts and Lyn Are Involved in Phagocytosis during Pseudomonas aeruginosa Infection
Authors: Kannan Shibichakravarthy , Audet Aaron , Huang Huang , Chen Li-juan , Wu Min 
Published: April 2014

Abstract
The mechanism of phagocytosis of pathogens remains to be fully characterized. We report a novel phagocytosis pathway for Pseudomonas aeruginosa, which is initiated by cholesterol-rich membrane rafts and is dependent on Lyn, primarily an immune regulator with both positive and negative roles. Blocking of Lyn or blocking of cholesterol synthesis significantly inhibited phagocytosis by alveolar macrophages. We found that Lyn, via Src homology 2 and 3 domains, bound to and then activated PI3K and Akt to regulate intracellular routing of the engulfed P. aeruginosa. Further analysis indicates that Lyn and raft components entered in phagosomes and late lysosomes. Finally, respiratory burst was dependent on Lyn and membrane rafts, as confirmed by small interfering RNA and dominant-negative strategies. Our investigations demonstrate that Lyn along with membrane rafts plays a fundamental role in phagocytosis by alveolar macrophages during infection.
IL-33, a Potent Inducer of Adaptive Immunity to Intestinal Nematodes
Authors: Humphreys Neil E. , Xu Damo , Hepworth Matthew R. , Liew Foo Y. , Grencis Richard K. 
Published: April 2014

Abstract
IL-33 (IL-1F11) binds ST2 (IL-1R4), both of which are associated with optimal CD4+ Th2 polarization. Exogenous IL-33 drives induction of Th2-associated cytokines and associated pathological changes within the gut mucosa. Th2 polarization is also a prerequisite to expulsion of the intestinal-dwelling nematode Trichuris muris. In this study, we demonstrate that IL-33 mRNA is expressed early during parasite infection and susceptible mice can be induced to expel the parasite by a regime of exogenous IL-33 administration. IL-33 prevents an inappropriate parasite-specific Th1-polarized response and induces IL-4, IL-9, and IL-13. This redirection requires the presence of T cells and must occur at the initiation of the response to the pathogen. Interestingly, exogenous IL-33 also induced thymic stromal lymphopoietin mRNA within the infected caecum, an epithelial cell-restricted cytokine essential for the generation of Th2-driven parasite immunity. IL-33 also acts independently of T cells, altering intestinal pathology in chronically infected SCID mice, leading to an increased crypt length and intestinal epithelial cell proliferation, but reducing goblet cell hyperplasia. Thus, the ability of IL-33 to induce Th2 responses has functional relevance in the context of intestinal helminth infection, particularly during the initiation of the response.
Novel Vaccination Protocol with Two Live Mucosal Vectors Elicits Strong Cell-Mediated Immunity in the Vagina and Protects against Vaginal Virus Challenge
Authors: Li Zhongxia , Zhang Manxin , Zhou Chenghui , Zhao Xinyan , Iijima Norifumi , Frankel Fred R. 
Published: April 2014

Abstract
Most HIV infections result from heterosexual transmission to women. Because cellular immunity plays a key role in the control of the infection, we sought to strengthen cellular immune responses in vaginal tissue. We explored a novel prime-boost protocol that used two live mucosal agents that trigger different pathways of innate immunity and induce strong cellular immunity. Adenovirus serotype 5 (Ad5) has frequently been used as a boost for DNA vaccines. In this study we used attenuated, recombinant L. monocytogenes-gag (rLm-gag) to prime mice by various mucosal routes—oral, intrarectal, and intravaginally (ivag)—followed by a systemic or mucosal boost with replication-defective rAd5-gag. Mice primed with a single administration of rLm-gag by any route and then boosted with rAd5-gag intramuscularly exhibited abundant Gag-specific CD8 T cells in spleen and vaginal lamina propria. Conversely, when boosted with rAd5-gag ivag, the immune response was reoriented toward the vagina with strikingly higher CD8 T cell responses in that tissue, particularly after ivag immunization by both vectors (ivag/ivag). Five weeks to 5 mo later, ivag/ivag-immunized mice continued to show high levels of effector memory CD8 T cells in vagina, while the pool of memory T cells in spleen assumed a progressively more central memory T cell phenotype. The memory mice showed high in vivo CTL activity in vagina, a strong recall response, and robust protection after ivag vaccinia-gag challenge, suggesting that this prime-boost strategy can induce strong cellular immunity, especially in vaginal tissues, and might be able to block the heterosexual transmission of HIV-1 at the vaginal mucosa.
A CD8+/CD103high T Cell Subset Regulates TNF-Mediated Chronic Murine Ileitis
Authors: Ho Johnson , Kurtz Courtney C. , Naganuma Makoto , Ernst Peter B. , Cominelli Fabio , Rivera-Nieves Jesús 
Published: April 2014

Abstract
Recruitment of lymphocytes to sites of inflammation requires the sequential engagement of adhesion molecules and chemokine receptors. Of these, the lectin-like molecule CD44 has been particularly implicated in inflammatory trafficking. Using a TNF-driven model of chronic ileitis (i.e., B6.129P-TnfΔARE mice) that recapitulates many features of Crohn’s disease, we demonstrate dynamic changes in the expression and functional state of CD44 on CD8+ T cells. These cells coexpress CD44 and L-selectin, giving them a surface phenotype similar to that of central memory T cells. Yet functionally they exhibit the phenotype of effector T cells, because they produce IFN-γ. Unexpectedly, depletion of the CD8+ population had no effect on the severity of ileitis. Further analyses showed a second CD8+ population that lacked CD44, but expressed CD103, produced TGF-β, inhibited the proliferation of CD4+ in vitro, and attenuated adoptively transferred ileitis in vivo, most likely counteracting the proinflammatory role of the CD44high subset. Collectively, these data suggest that the presence or absence of CD44 and CD103 on the CD8+ lymphocyte surface defines functionally distinct subsets of CD8+ T cells in vivo. These inflammation-driven populations exert distinct roles during the development of chronic ileitis, and influence the balance of effector and regulatory functions in the chronically inflamed small intestine.
Intestinal Inflammation Increases the Expression of the P2Y6 Receptor on Epithelial Cells and the Release of CXC Chemokine Ligand 8 by UDP
Authors: Grbic Djordje M. , Degagné Émilie , Langlois Christine , Dupuis Andrée-Anne , Gendron Fernand-Pierre 
Published: April 2014

Abstract
Epithelial cells participate in the immune response of the intestinal mucosa. Extracellular nucleotides have been recognized as inflammatory molecules. We investigated the role of extracellular nucleotides and their associated P2Y receptors in the secretion of cytokines by epithelial cells. The effect of intestinal inflammation on P2Y6 receptor expression was determined by PCR in the mouse, rat, and human. Localization of the P2Y6 receptor was determined by immunofluorescence microscopy in the colon of normal and dextran sulfate sodium-treated mice. The effect of P2Y6 activation by UDP on cytokine expression and release by epithelial cells was determined using a combination of Western blots, luciferase assays, RT-PCR, cytokine Ab arrays, and ELISA. Inflammation up-regulates P2Y2 as well as P2Y6 receptor expression in the mucosa of the colon of colitic mice. In vitro, we demonstrated that UDP could be released by Caco-2/15 cells. We have confirmed the increased expression of P2Y6 by challenging intestinal epithelial cell-6 and Caco-2/15 cells with TNF-α and IFN-γ and showing that stimulation of epithelial cells by UDP results in an increased expression and release of CXCL8 by an ERK1/2-dependent mechanism. The increase in CXCL8 expression was associated with a transcriptional activation by the P2Y6 receptor. This study is the first report demonstrating the implication of P2Y receptors in the inflammatory response of intestinal epithelial cells. We show for the first time that P2Y6, as well as P2Y2, expression is increased by the stress associated with intestinal inflammation. These results demonstrate the emergence of extracellular nucleotide signaling in the orchestration of intestinal inflammation.
β-Glucan Activates Microglia without Inducing Cytokine Production in Dectin-1-Dependent Manner
Authors: Shah Vaibhav B. , Huang Yongcheng , Keshwara Rohan , Ozment-Skelton Tammy , Williams David L. , Keshvara Lakhu 
Published: April 2014

Abstract
Microglia are the resident mononuclear phagocytic cells that are critical for innate and adaptive responses within the CNS. Like other immune cells, microglia recognize and are activated by various pathogen-associated molecular patterns. β-glucans are pathogen-associated molecular patterns present within fungal cell walls that are known to trigger protective responses in a number of immune cells. In an effort to better understand microglial responses to β-glucans and the underlying response pathways, we sought to determine whether Dectin-1, a major β-glucan receptor recently identified in leukocytes, plays a similar role in β-glucan-induced activation in microglia. In this study, we report that Dectin-1 is indeed expressed on the surface of murine primary microglia, and engagement of the receptor with particulate β-glucan resulted in an increase in tyrosine phosphorylation of spleen tyrosine kinase, a hallmark feature of the Dectin-1 signaling pathway. Moreover, phagocytosis of β-glucan particles and subsequent intracellular production of reactive oxygen species were also mediated by Dectin-1. However, unlike in macrophages and dendritic cells, β-glucan-mediated microglial activation did not result in significant production of cytokines or chemokines; thus, the interaction of microglial Dectin-1 with glucan elicits a unique response. Our results suggest that the Dectin-1 pathway may play an important role in antifungal immunity in the CNS.
RhoA Is Involved in LFA-1 Extension Triggered by CXCL12 but Not in a Novel Outside-In LFA-1 Activation Facilitated by CXCL9
Authors: Pasvolsky Ronit , Grabovsky Valentin , Giagulli Cinzia , Shulman Ziv , Shamri Revital , Feigelson Sara W. , Laudanna Carlo , Alon Ronen 
Published: April 2014

Abstract
Chemokines presented on endothelial tissues instantaneously trigger LFA-1-mediated arrest on ICAM-1 via rapid inside-out and outside-in (ligand-driven) LFA-1 activation. The GTPase RhoA was previously implicated in CCL21-triggered LFA-1 affinity triggering in murine T lymphocytes and in LFA-1-dependent adhesion strengthening to ICAM-1 on Peyer’s patch high endothelial venules stabilized over periods of at least 10 s. In this study, we show that a specific RhoA 23/40 effector region is vital for the initial LFA-1-dependent adhesions of lymphocytes on high endothelial venules lasting 1–3 s. Blocking the RhoA 23/40 region in human T lymphocytes in vitro also impaired the subsecond CXCL12-triggered LFA-1-mediated T cell arrest on ICAM-1 by eliminating the rapid induction of an extended LFA-1 conformational state. However, the inflammatory chemokine CXCL9 triggered robust LFA-1-mediated T lymphocyte adhesion to ICAM-1 at subsecond contacts independently of the RhoA 23/40 region. CXCL9 did not induce conformational changes in the LFA-1 ectodomain, suggesting that particular chemokines can activate LFA-1 through outside-in post ligand binding stabilization changes. Like CXCL9, the potent diacylglycerol-dependent protein kinase C agonist PMA was found to trigger LFA-1 adhesiveness to ICAM-1 also without inducing integrin extension or an a priori clustering and independently of the RhoA 23/40 region. Our results collectively suggest that the 23/40 region of RhoA regulates chemokine-induced inside-out LFA-1 extension before ligand binding, but is not required for a variety of chemokine and non-chemokine signals that rapidly strengthen LFA-1-ICAM-1 bonds without an a priori induction of high-affinity extended LFA-1 conformations.
STAT3 Is Indispensable to IL-27-Mediated Cell Proliferation but Not to IL-27-Induced Th1 Differentiation and Suppression of Proinflammatory Cytokine Production
Authors: Owaki Toshiyuki , Asakawa Masayuki , Morishima Noriko , Mizoguchi Izuru , Fukai Fumio , Takeda Kiyoshi , Mizuguchi Junichiro , Yoshimoto Takayuki 
Published: April 2014

Abstract
IL-27, a member of the IL-6/IL-12 family, activates both STAT1 and STAT3 through its receptor, which consists of WSX-1 and gp130 subunits, resulting in augmentation of Th1 differentiation and suppression of proinflammatory cytokine production. In the present study, we investigated the role of STAT3 in the IL-27-mediated immune functions. IL-27 induced phosphorylation of STAT1, -2, -3 and -5 in wild-type naive CD4+ T cells, but failed to induce that of STAT3 and STAT5 in STAT3-deficient cohorts. IL-27 induced not only proinflammatory responses including up-regulation of ICAM-1, T-box expressed in T cells, and IL-12Rβ2 and Th1 differentiation, but also anti-inflammatory responses including suppression of proinflammatory cytokine production such as IL-2, IL-4, and IL-13 even in STAT3-deficient naive CD4+ T cells. In contrast, IL-27 augmented c-Myc and Pim-1 expression and induced cell proliferation in wild-type naive CD4+ T cells but not in STAT3-deficient cohorts. Moreover, IL-27 failed to activate STAT3, augment c-Myc and Pim-1 expression, and induce cell proliferation in pro-B BaF/3 transfectants expressing mutant gp130, in which the putative STAT3-binding four Tyr residues in the YXXQ motif of the cytoplasmic region was replaced by Phe. These results suggest that STAT3 is activated through gp130 by IL-27 and is indispensable to IL-27-mediated cell proliferation but not to IL-27-induced Th1 differentiation and suppression of proinflammatory cytokine production. Thus, IL-27 may be a cytokine, which activates both STAT1 and STAT3 through distinct receptor subunits, WSX-1 and gp130, respectively, to mediate its individual immune functions.