bluuebunny/crossref_metadata_2025_split huggingface dataset:
IL-18 Contributes to Host Resistance Against Infection withPseudomonas aeruginosaThrough Induction of IFN-γ Production
Authors: Huang Xi , McClellan Sharon A. , Barrett Ronald P. , Hazlett Linda D. 
Published: April 2014

AbstractPseudomonas aeruginosa keratitis destroys the cornea in susceptible (B6), but not resistant (BALB/c) mice. To determine mechanisms mediating resistance, the role of IFN-γ, IL-12, and IL-18 was tested in BALB/c mice. RT-PCR analysis detected IFN-γ mRNA expression levels in cornea that were significantly increased at 1–7 days postinfection. IL-18 mRNA was detected constitutively in cornea and, at 1–7 days postinfection, levels were elevated significantly, while no IL-12 mRNA was similarly detected. To test whether IL-18 contributed to IFN-γ production, mice were treated with anti-IL-18 mAb. Treatment decreased corneal IFN-γ mRNA levels, and bacterial load and disease increased/worsened, compared with IgG-treated mice. To stringently examine the role of IFN-γ in bacterial killing, knockout (−/−) vs wild-type (wt) mice also were tested. All corneas perforated, and bacterial load was increased significantly in −/− vs wt mice. Because disease severity was increased in IFN-γ−/− vs IL-18-neutralized mice, and since IL-18 also induces production of TNF, we tested for TNF-α in both groups. ELISA analysis demonstrated significantly elevated corneal TNF-α protein levels in IFN-γ−/− vs wt mice after infection. In contrast, RT-PCR analysis of IL-18-neutralized vs IgG-treated infected mice revealed decreased corneal TNF-α mRNA expression. Next, to resolve whether TNF was required for bacterial killing, TNF-α was neutralized in BALB/c mice. No difference in corneal bacterial load was detected in neutralized vs IgG-treated mice. These data provide evidence that IL-18 contributes to the resistance response by induction of IFN-γ and that IFN-γ is required for bacterial killing.
Cutting Edge: Transmembrane Phosphoprotein Csk-Binding Protein/Phosphoprotein Associated With Glycosphingolipid-Enriched Microdomains as a Negative Feedback Regulator of Mast Cell Signaling Through the FcεRI
Authors: Ohtake Hidenori , Ichikawa Naoki , Okada Masato , Yamashita Toshiyuki 
Published: April 2014

Abstract
Tyrosine phosphorylation in the cytoplasmic domains of FcεRI by the Src family kinase Lyn initiates a signaling cascade leading to mast cell activation. In this study, we show that a recently identified transmembrane protein, Csk-binding protein (Cbp), also known as phospoprotein associated with glycosphingolipid-enriched microdomains (PAG), negatively regulates FcεRI signaling. In rat basophilic leukemia (RBL)-2H3 cells, the levels of tyrosine phosphorylation of Cbp/PAG and its association with Csk, a negative regulator for Lyn, significantly elevate immediately after aggregation of FcεRI. An overexpression of Cbp/PAG in RBL-2H3 cells inhibits FcεRI-mediated cell activation. This is accompanied with decreased levels of tyrosine phosphorylation of FcεRI, association of FcεRI with Lyn, and FcεRI-associated tyrosine kinase activity. These findings combined with the fact that Cbp/PAG, Lyn, and aggregated FcεRI are localized to lipid rafts, suggest that upon FcεRI aggregation Cbp/PAG down-regulates the receptor-associated Lyn activity through relocating Csk to rafts, thereby efficiently mediating feedback inhibition of FcεRI signaling.
Lipid Raft Heterogeneity in Human Peripheral Blood T Lymphoblasts: A Mechanism for Regulating the Initiation of TCR Signal Transduction
Authors: Schade Andrew E. , Levine Alan D. 
Published: April 2014

Abstract
Lateral mobility and spatial organization of proteins within the plasma membrane are likely to mediate the initial events coordinating T cell activation. Lipid rafts, distinct cholesterol/sphingolipid-rich membrane microdomains, provide a mechanism for this regulation by concentrating or excluding signaling proteins. We demonstrate in peripheral blood T cell lymphoblasts that immediate early phosphotyrosine signal transduction through the TCR complex is functionally dependent on a distinct population of lipid rafts. Specifically, cholesterol extraction destabilizes the membrane microdomains containing Lck, while the rafts containing the adapter protein linker for activation of T cells remain intact. Heterogeneity in the partitioning of these proteins in resting cells was confirmed by immunoelectron microscopy. After T cell activation, both Lck and the linker for activation of T cells colocalize to 50–100 nm microdomains in the plasma membrane, indicating that sequestration of these proteins into distinct lipid rafts may function to regulate the initiation of T cell signal transduction.
The Role of the CPNKEKEC Sequence in the β2 Subunit I Domain in Regulation of Integrin αLβ2 (LFA-1)
Authors: Kamata Tetsuji , Tieu Kenneth Khiem , Tarui Takehiko , Puzon-McLaughlin Wilma , Hogg Nancy , Takada Yoshikazu 
Published: April 2014

Abstract
The αL I (inserted or interactive) domain of integrin αLβ2 undergoes conformational changes upon activation. Recent studies show that the isolated, activated αL I domain is sufficient for strong ligand binding, suggesting the β2 subunit to be only indirectly involved. It has been unclear whether the activity of the αL I domain is regulated by the β2 subunit. In this study, we demonstrate that swapping the disulfide-linked CPNKEKEC sequence (residues 169–176) in the β2 I domain with a corresponding β3 sequence, or mutating Lys174 to Thr, constitutively activates αLβ2 binding to ICAM-1. These mutants do not require Mn2+ for ICAM-1 binding and are insensitive to the inhibitory effect of Ca2+. We have also localized a component of the mAb 24 epitope (a reporter of β2 integrin activation) in the CPNKEKEC sequence. Glu173 and Glu175 of the β2 I domain are identified as critical for mAb 24 binding. Because the epitope is highly expressed upon β2 integrin activation, it is likely that the CPNKEKEC sequence is exposed or undergoes conformational changes upon activation. Deletion of the αL I domain did not eliminate the mAb 24 epitope. This confirms that the αL I domain is not critical for mAb 24 binding, and indicates that mAb 24 detects a change expressed in part in the β2 subunit I domain. These results suggest that the CPNKEKEC sequence of the β2 I domain is involved in regulating the αL I domain.
Endotoxin-Neutralizing Antimicrobial Proteins of the Human Placenta
Authors: Kim Hun Sik , Cho Ju Hyun , Park Hyoung Woo , Yoon Ho , Kim Mi Sun , Kim Sun Chang 
Published: April 2014

Abstract
Microbial colonization and infection of placental tissues often lead to adverse pregnancy outcomes such as preterm birth, a leading cause of neonatal morbidity and mortality. The fetal membranes of the placenta, a physical and active barrier to microbial invasion, encapsulate the fetus and secure its intrauterine environment. To examine the innate defense system of the human placenta, antimicrobial peptides were isolated from the fetal membranes of human placenta and characterized biochemically. Two salt-resistant antimicrobial host proteins were purified to homogeneity using heparin-affinity and reversed-phase HPLC. Characterization of these proteins revealed that they are identical to histones H2A and H2B. Histones H2A and H2B showed dose-dependent inhibition of the endotoxin activity of LPS and inhibited this activity by binding to and therefore blocking both the core and lipid A moieties of LPS. Consistent with a role for histones in the establishment of placental innate defense, histones H2A and H2B were highly expressed in the cytoplasm of syncytiotrophoblasts and amnion cells, where the histone proteins were localized mainly to the epithelial surface. Furthermore, culturing of amnion-derived WISH cells led to the constitutive release of histone H2B, and histones H2A and H2B contribute to bactericidal activity of amniotic fluid. Our studies suggest that histones H2A and H2B may endow the epithelium of the placenta with an antimicrobial and endotoxin-neutralizing barrier against microorganisms that invade this immune-privileged site.
Peroxisome Proliferator-Activated Receptor-γ Agonist 15-Deoxy-Δ12,1412,14-Prostaglandin J2 Ameliorates Experimental Autoimmune Encephalomyelitis
Authors: Diab Asim , Deng Caishu , Smith Jeff D. , Hussain Rehana Z. , Phanavanh Bounleut , Lovett-Racke Amy E. , Drew Paul D. , Racke Michael K. 
Published: April 2014

Abstract
Peroxisome proliferator-activated receptors (PPAR) are members of a nuclear hormone receptor superfamily that includes receptors for steroids, retinoids, and thyroid hormone, all of which are known to affect the immune response. Previous studies dealing with PPAR-γ expression in the immune system have been limited. Recently, PPAR-γ was identified in monocyte/macrophage cells. In this study we examined the role of PPAR-γ in experimental autoimmune encephalomyelitis (EAE), an animal model for the human disease multiple sclerosis. The hypothesis we are testing is whether PPAR-γ plays an important role in EAE pathogenesis and whether PPAR-γ ligands can inhibit the clinical expression of EAE. Initial studies have shown that the presence of the PPAR-γ ligand 15-deoxy-Δ12,14-PGJ2 (15d-PGJ2) inhibits the proliferation of Ag-specific T cells from the spleen of myelin basic protein Ac1–11 TCR-transgenic mice. 15d-PGJ2 suppressed IFN-γ, ΙL-10, and IL-4 production by both Con A- and myelin basic protein Ac1–11 peptide-stimulated lymphocytes as determined by ELISA and ELISPOT assay. Culture of encephalitogenic T cells with 15d-PGJ2 in the presence of Ag reduced the ability of these cells to adoptively transfer EAE. Examination of the target organ, the CNS, during the course of EAE revealed expression of PPAR-γ in the spinal cord inflammatory infiltrate. Administration of 15d-PGJ2 before and at the onset of clinical signs of EAE significantly reduced the severity of disease. These results suggest that PPAR-γ ligands may be a novel therapeutic agent for diseases such as multiple sclerosis.
Ultraviolet B Radiation Induces a Transient Appearance of IL-4+ Neutrophils, Which Support the Development of Th2 Responses
Authors: Teunissen Marcel B. M. , Piskin Gamze , Nuzzo Sergio di , Sylva-Steenland Regien M. R. , de Rie Menno A. , Bos Jan D. 
Published: April 2014

AbstractUVB irradiation can cause considerable changes in the composition of cells in the skin and in cutaneous cytokine levels. We found that a single exposure of normal human skin to UVB induced an infiltration of numerous IL-4+ cells. This recruitment was detectable in the papillary dermis already 5 h after irradiation, reaching a peak at 24 h and declining gradually thereafter. The IL-4+ cells appeared in the epidermis at 24 h postradiation and reached a plateau at days 2 and 3. The number of IL-4+ cells was markedly decreased in both dermis and epidermis at day 4, and at later time points, the IL-4 expression was absent. The IL-4+ cells did not coexpress CD3 (T cells), tryptase (mast cells), CD56 (NK cells), and CD36 (macrophages). They did coexpress CD15 and CD11b, showed a clear association with elastase, and had a multilobed nucleus, indicating that UVB-induced infiltrating IL-4+ cells are neutrophils. Blister fluid from irradiated skin, but not from control skin, contained IL-4 protein as well as increased levels of IL-6, IL-8, and TNF-α. In contrast to control cultures derived from nonirradiated skin, a predominant type 2 T cell response was detected in T cells present in primary dermal cell cultures derived from UVB-exposed skin. This type 2 shift was abolished when CD15+ cells (i.e., neutrophils) were depleted from the dermal cell suspension before culturing, suggesting that neutrophils favor type 2 T cell responses in UVB-exposed skin.
Maturation and Activation of Dendritic Cells Induced by Lymphocyte Activation Gene-3 (CD223)
Authors: Andreae Susanne , Piras Fabienne , Burdin Nicolas , Triebel Frédéric 
Published: April 2014

AbstractLymphocyte activation gene-3 (LAG-3) is an MHC class II ligand expressed on activated T and NK cells. A LAG-3Ig fusion protein has been used in mice as an adjuvant protein to induce antitumor responses and specific CD8 and CD4 Th1 responses to nominal Ags. In this work we report on the effect of LAG-3Ig on the maturation and activation of human monocyte-derived dendritic cells (DC). LAG-3Ig binds MHC class II molecules expressed in plasma membrane lipid rafts on immature human DC and induces rapid morphological changes, including the formation of dendritic projections. LAG-3Ig markedly up-regulates the expression of costimulatory molecules and the production of IL-12 and TNF-α. Consistent with this effect on DC maturation, LAG-3Ig disables DC in their capacity to capture soluble Ags. These events are associated with the acquisition of professional APC function, because LAG-3Ig increases the capacity of DC to stimulate the proliferation and IFN-γ response by allogeneic T cells. These effects were not observed when using ligation of MHC class II by specific mAb. Class II-mediated signals induced by a natural ligand, LAG-3, lead to complete maturation of DC, which acquire the capacity to trigger naive T cells and drive polarized Th1 responses.
Phenotypic and Functional Heterogeneity of EBV Epitope-Specific CD8+ T Cells
Authors: Catalina Michelle D. , Sullivan John L. , Brody Robin M. , Luzuriaga Katherine 
Published: April 2014

Abstract
High frequencies of EBV-specific CD8+ T cells have been detected during acute EBV infection, yet persistent infection inevitably results. To address this issue, we characterized the phenotype and function of epitope-specific CD8+ T cell populations from presentation with acute through latent infection. Considerable phenotypic and functional heterogeneity within, as well as between, two different epitope-specific populations was observed over time following acute infection. B7 EBV-encoded nuclear Ag (EBNA)-3A-specific CD8+ T cells expressed only CD45RO from acute through latent EBV infection. A2 BMLF-1-specific CD8+ T cells expressed CD45RO during acute infection and either CD45RA or CD45RO during latent EBV infection. This difference in CD45 isoform expression between the two epitope-specific populations did not translate into differences in perforin content, the ability to produce IFN-γ, or the ability to proliferate in response to Ag in vitro. In individuals with latent EBV infection, the frequencies of A2 BMLF-1- or B7 EBNA-3A-specific CD8+ T cells that expressed CD45RA, CD45RO, CD62 ligand, CCR7, and perforin were stable over time. However, the expression of CD62 ligand and CCR7 was significantly higher among EBNA-3A-specific CD8+ T cells than among BMLF-1-specific CD8+ T cells. Further work is necessary to understand how phenotypic and functional differences between EBV epitope-specific CD8+ T cells are related to the biology of the virus and to the equilibrium between the virus and the host during persistent infection.
Requirement for the Lymphocyte Semaphorin, CD100, in the Induction of Antigen-Specific T Cells and the Maturation of Dendritic Cells
Authors: Kumanogoh Atsushi , Suzuki Kazuhiro , Ch’ng EweSeng , Watanabe Chie , Marukawa Satoko , Takegahara Noriko , Ishida Isao , Sato Takehito , Habu Sonoko , Yoshida Kanji , Shi Wei , Kikutani Hitoshi 
Published: April 2014

AbstractCD100 belongs to the semaphorin family, several members of which are known to act as repulsive axonal guidance factors during neuronal development. We have previously demonstrated that CD100 plays a crucial role in humoral immunity. In this study, we show that CD100 is also important for cellular immunity through the maturation of dendritic cells (DCs). CD100−/− mice fail to develop experimental autoimmune encephalomyelitis induced by myelin oligodendrocyte glycoprotein peptide, because myelin oligodendrocyte glycoprotein-specific T cells are not generated in the absence of CD100. In vitro studies with T cells from OVA-specific TCR-transgenic mice demonstrate that Ag-specific T cells lacking CD100 fail to differentiate into cells producing either IL-4 or IFN-γ in the presence of APCs and OVA peptide. In addition, DCs from CD100−/− mice display poor allostimulatory capabilities and defects in costimulatory molecule expression and IL-12 production. The addition of exogenous soluble rCD100 restores normal functions in CD100−/− DCs and further enhances functions of normal DCs. Furthermore, treatment of Ag-pulsed DCs with both soluble CD100 and anti-CD40 before immunization significantly enhances their immunogenicity. This treatment elicits improved T cell priming in vivo, enhancing both primary and memory T cell responses. Collectively, these results demonstrate that CD100, which enhances the maturation of DCs, is essential in the activation and differentiation of Ag-specific T cells.
A Role for theCr2Gene in Modifying Autoantibody Production in Systemic Lupus Erythematosus
Authors: Wu Xiaobo , Jiang Ning , Deppong Christine , Singh Jasvinder , Dolecki Gregory , Mao Dailing , Morel Laurence , Molina Hector D. 
Published: April 2014

AbstractSystemic lupus erythematosus is an autoimmune disease characterized by autoantibody production against nuclear Ags. Recent studies suggest that the Cr2 gene, which encodes for complement receptor (CR)1 and CR2, is important in disease susceptibility. Because the precise disease phenotype related to this gene, in isolation or in relation to other genetic loci, is not known, we analyzed C57BL/6 mice with a targeted mutation in Cr2 (C57BL/6.Cr2−/−) with or without a concomitant mutation in Fas (C57BL/6.lpr Cr2−/−). The Cr2null mutation in a C57BL/6.lpr background markedly increases the serum concentrations of IgG1 and IgG2b and the levels of antinuclear and anti-dsDNA Abs as compared with C57BL/6.lpr controls. There is also a trend for higher concentrations of IgG2a and IgG3. In contrast, isolated deficiencies in either these CRs or Fas have a limited effect in the production of anti-dsDNA Abs. Moreover, the Cr2null mutation does not affect other disease manifestations. These findings demonstrate that abnormalities in CR1 and CR2 may be linked to the production of autoantibodies by modifying the effect of other systemic lupus erythematosus susceptibility genes. Phenotypic expression of other disease manifestations need additional Cr2-independent genetic factors.
Two Phenotypically Distinct Subsets of Spleen Dendritic Cells in Rats Exhibit Different Cytokine Production and T Cell Stimulatory Activity
Authors: Voisine Cécile , Hubert Francois-Xavier , Trinité Benjamin , Heslan Michèle , Josien Régis 
Published: April 2014

Abstract
We recently reported that splenic dendritic cells (DC) in rats can be separated into CD4+ and CD4− subsets and that the CD4− subset exhibited a natural cytotoxic activity in vitro against tumor cells. Moreover, a recent report suggests that CD4− DC could have tolerogenic properties in vivo. In this study, we have analyzed the phenotype and in vitro T cell stimulatory activity of freshly isolated splenic DC subsets. Unlike the CD4− subset, CD4+ splenic DC expressed CD5, CD90, and signal regulatory protein α molecules. Both fresh CD4− and CD4+ DC displayed an immature phenotype, although CD4+ cells constitutively expressed moderate levels of CD80. The half-life of the CD4−, but not CD4+ DC in vitro was extremely short but cells could be rescued from death by CD40 ligand, IL-3, or GM-CSF. The CD4− DC produced large amounts of the proinflammatory cytokines IL-12 and TNF-α and induced Th1 responses in allogeneic CD4+ T cells, whereas the CD4+ DC produced low amounts of IL-12 and no TNF-α, but induced Th1 and Th2 responses. As compared with the CD4+ DC that strongly stimulated the proliferation of purified CD8+ T cells, the CD4− DC exhibited a poor CD8+ T cell stimulatory capacity that was substantially increased by CD40 stimulation. Therefore, as previously shown in mice and humans, we have identified the existence of a high IL-12-producing DC subset in the rat that induces Th1 responses. The fact that both the CD4+ and CD4− DC subsets produced low amounts of IFN-α upon viral infection suggests that they are not related to plasmacytoid DC.
Prostaglandins Inhibit 5-Lipoxygenase-Activating Protein Expression and Leukotriene B4 Production from Dendritic Cells Via an IL-10-Dependent Mechanism
Authors: Harizi Hedi , Juzan Monique , Moreau Jean-François , Gualde Norbert 
Published: April 2014

Abstract
PGs produced from arachidonic acid by the action of cyclooxygenase enzymes play a pivotal role in the regulation of both inflammatory and immune responses. Because leukotriene B4 (LTB4), a product of 5-lipoxygenase (5-LO) pathway, can exert numerous immunoregulatory and proinflammatory activities, we examined the effects of PGs on LTB4 release from dendritic cells (DC) and from peritoneal macrophages. In concentration-dependent manner, PGE1 and PGE2 inhibited the production of LTB4 from DC, but not from peritoneal macrophage, with an IC50 of 0.04 μM. The same effect was observed with MK-886, a 5-LO-activating protein (FLAP)-specific inhibitor. The decreased release of LTB4 was associated with an enhanced level of IL-10. Furthermore, the inhibition of LTB4 synthesis by PGs was significantly reversed by anti-IL-10, suggesting the involvement of an IL-10-dependent mechanism. Hence, we examined the effects of exogenous IL-10 on the 5-LO pathway. We demonstrate that IL-10 suppresses the production of LTB4 from DC by inhibiting FLAP protein expression without any effect on 5-LO and cytosolic phospholipase A2. Taken together, our results suggest links between DC cyclooxygenase and 5-LO pathways during the inflammatory response, and FLAP is a key target for the PG-induced IL-10-suppressive effects.
A Role for Stat5 in CD8+ T Cell Homeostasis
Authors: Kelly John , Spolski Rosanne , Imada Kazunori , Bollenbacher Julie , Lee Stephen , Leonard Warren J. 
Published: April 2014

Abstract
Cytokine signals are known to contribute to CD8+ memory T cell homeostasis, but an exact understanding of the mechanism(s) has remained elusive. We have now investigated the role of Stat5 proteins in this process. Whereas Stat5a and Stat5b KO mice have decreased numbers of CD8+ T cells, Stat5-transgenic mice have an increased number of these cells. Stat5b-transgenic mice exhibit increased Ag-induced cell death of CD4+ T cells and augmented proliferation and Bcl-2 expression in CD8+ T cells, providing a basis for this finding. Moreover, CD8+ memory T cells are substantially affected by Stat5 levels. These findings identify Stat5 proteins as critical signaling mediators used by cytokines to regulate CD8+ T cell homeostasis.
Efficient Induction of Primary and Secondary T Cell-Dependent Immune Responses In Vivo in the Absence of Functional IL-2 and IL-15 Receptors
Authors: Yu Aixin , Zhou Jiehao , Marten Norman , Bergmann Cornelia C. , Mammolenti Michele , Levy Robert B. , Malek Thomas R. 
Published: April 2014

Abstract
IL-2 and IL-15 are thought to be important cytokines for T cell-dependent immune responses. Mice deficient in IL-2, IL-2Rα, and IL-2Rβ are each characterized by a rapid lethal autoimmune lymphoproliferative disorder that complicates their use in studies aimed at investigating the role of these cytokines and receptors for immune responses in vivo. We have previously characterized a novel transgenic (Tg) mouse on the IL-2Rβ−/− genetic background (Tg−/− mice) that lacks autoimmune disease but still contains peripheral T cells that are nonresponsive to IL-2 and IL-15. In the present study, these mice were used to investigate the extent by which IL-2 and IL-15 are essential for T cell immunity in vivo. Tg−/− mice generated near normal primary and secondary Ab responses to OVA, readily mounted first and second set allogeneic skin graft rejection responses, and developed primary and recall CD8 T cell responses to vaccinia virus. However, Tg−/− mice generated a slightly lower level of IgG2a Abs to OVA, exhibited a somewhat delayed first set skin graft rejection response with lower allo-specific CTL, and developed a significantly lower number of IFN-γ-producing vaccinia-specific CD8+ T cells. Thus, although T effector function is somewhat impaired, T cell immunity is largely functional in the absence of IL-2- and IL-15-induced signaling through IL-2Rβ.