bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cutting Edge: Th2 Response Induction by Dendritic Cells: A Role for CD40
Authors: MacDonald Andrew S. , Straw Amy D. , Dalton Nicole M. , Pearce Edward J. 
Published: April 2014

AbstractWe investigated the influence of dendritic cell (DC) CD40 expression on Th2 and Th1 development by in vivo transfer of Ag-pulsed bone marrow-derived DC generated from wild-type (WT) or CD40−/− mice. Contrary to expectation, CD40−/− DC primed with Ag that inherently induce a Th2 response (soluble egg Ag from Schistosoma mansoni) failed to induce a Th2 response or any compensatory Th1 response, whereas CD40−/−DC primed with Ag that inherently induce a Th1 response (Propionibacterium acnes) generated a competent Th1 response. Thus, DC expression of CD40 is a prerequisite for initiation of Th2, but not Th1, responses by these Ag. Consistent with this, CD154−/− mice, unlike WT mice, failed to mount a Th2 response when directly injected with schistosome eggs but mounted a normal Th1 response after challenge with P. acnes. CD40-CD154 interaction can therefore play a major role in Th2 response induction.
Cutting Edge: Negative Regulation of Immune Synapse Formation by Anchoring Lipid Raft to Cytoskeleton Through Cbp-EBP50-ERM Assembly
Authors: Itoh Katsuhiko , Sakakibara Masahiro , Yamasaki Sho , Takeuchi Arata , Arase Hisashi , Miyazaki Masaru , Nakajima Nobuyuki , Okada Masato , Saito Takashi 
Published: April 2014

Abstract
Ag recognition by T lymphocytes induces immune synapse formation and recruitment of signaling molecules into a lipid raft. Cbp/PAG is a Csk-associated membrane adapter protein exclusively localized in a lipid raft. We identified NHERF/EBP50 as a Cbp-binding molecule, which connects the membrane raft and cytoskeleton by binding to both Cbp through its PDZ domain and ezrin-radixin-moesin through the C terminus. Overexpression of Cbp reduced the mobility of the raft on the cell surface of unstimulated T cells and prevented synapse formation and subsequent T cell activation, whereas a mutant incapable of EBP50 binding restored both synapse formation and activation. These results suggest that anchoring of lipid raft to the cytoskeleton through Cbp-EBP50-ezrin-radixin-moesin assembly regulates membrane dynamism for synapse formation and T cell activation.
Indirect IL-4 Pathway in Type 1 Immunity
Authors: Karulin Alexey Y. , Hesse Maike D. , Yip Hualin C. , Lehmann Paul V. 
Published: April 2014

AbstractRecall Ag-specific IL-4 was detected in the spleen and in the blood, but not in lymph nodes of mice in which polarized type 1 immunity was induced. This IL-4 was not produced by T cells, but soluble factors secreted by the recall Ag-activated T cells, including IL-3, triggered cells of the innate immune system, primarily mast cells, to secrete IL-4. This notion has profound implications for immunodiagnostics: the detection of apparently recall Ag-specific IL-4 does not necessarily reflect the presence of Th2 or Th0 memory T cells with long-term cytokine commitment as is of interest for assessing adoptive immunity. We found that in vivo the indirect IL-4 pathway did not suffice to trigger IgE isotype switching, but promoted IgG1 production and inhibited type 1 T cell differentiation. Therefore, the indirect IL-4 pathway can explain partial type 2 immune response phenotypes in vivo in face of unipolar Th1 T cell immunity. The representation of mast cells in different tissues may explain why immune responses in certain organs are more type 2 biased. Therefore, the indirect pathway of IL-4 production represents a novel type of interaction between the innate and the adoptive immune system that can contribute to the outcome of host defense and immune pathology.
Tissue Expression of Human Toll-Like Receptors and Differential Regulation of Toll-Like Receptor mRNAs in Leukocytes in Response to Microbes, Their Products, and Cytokines
Authors: Zarember Kol A. , Godowski Paul J. 
Published: April 2014

AbstractMembers of the Toll-like receptor (TLR) family mediate dorsoventral patterning and cellular adhesion in insects as well as immune responses to microbial products in both insects and mammals. TLRs are characterized by extracellular leucine-rich repeat domains and an intracellular signaling domain that shares homology with cytoplasmic sequences of the mammalian IL-1 receptor and plant disease resistance genes. Ten human TLRs have been cloned as well as RP105, a protein similar to TLR4 but lacking the intracellular signaling domain. However, only five TLRs have described functions as receptors for bacterial products (e.g., LPS, lipoproteins). To identify potential sites of action, we used quantitative real-time RT-PCR to examine systematically the expression of mRNAs encoding all known human TLRs, RP105, and several other proteins important in TLR functions (e.g., MD-1, MD-2, CD14, MyD88). Most tissues tested expressed at least one TLR, and several expressed all (spleen, peripheral blood leukocytes). Analysis of TLR expression in fractionated primary human leukocytes (CD4+, CD8+, CD19+, monocytes, and granulocytes) indicates that professional phagocytes express the greatest variety of TLR mRNAs although several TLRs appear more restricted to B cells, suggesting additional roles for TLRs in adaptive immunity. Monocyte-like THP-1 cells regulate TLR mRNA levels in response to a variety of stimuli including phorbol esters, LPS, bacterial lipoproteins, live bacteria, and cytokines. Furthermore, addition of Escherichia coli to human blood ex vivo caused distinct changes in TLR expression, suggesting that important roles exist for these receptors in the establishment and resolution of infections and inflammation.
Potent CD4+ T Cell Responses Elicited by a Bicistronic HIV-1 DNA Vaccine Expressing gp120 and GM-CSF
Authors: Barouch Dan H. , Santra Sampa , Tenner-Racz Klara , Racz Paul , Kuroda Marcelo J. , Schmitz Joern E. , Jackson Shawn S. , Lifton Michelle A. , Freed Dan C. , Perry Helen C. , Davies Mary-Ellen , Shiver John W. , Letvin Norman L. 
Published: April 2014

AbstractVirus-specific CD4+ T cell responses have been shown to play a critical role in controlling HIV-1 replication. Candidate HIV-1 vaccines should therefore elicit potent CD4+ as well as CD8+ T cell responses. In this report we investigate the ability of plasmid GM-CSF to augment CD4+ T cell responses elicited by an HIV-1 gp120 DNA vaccine in mice. Coadministration of a plasmid expressing GM-CSF with the gp120 DNA vaccine led to only a marginal increase in gp120-specific splenocyte CD4+ T cell responses. However, immunization with a bicistronic plasmid that coexpressed gp120 and GM-CSF under control of a single promoter led to a dramatic augmentation of vaccine-elicited CD4+ T cell responses, as measured by both cellular proliferation and ELISPOT assays. This augmentation of CD4+ T cell responses was selective, since vaccine-elicited Ab and CD8+ T cell responses were not significantly changed by the addition of GM-CSF. A 100-fold lower dose of the gp120/GM-CSF bicistronic DNA vaccine was required to elicit detectable gp120-specific splenocyte proliferative responses compared with the monocistronic gp120 DNA vaccine. Consistent with these findings, i.m. injection of the gp120/GM-CSF bicistronic DNA vaccine evoked a more extensive cellular infiltrate at the site of inoculation than the monocistronic gp120 DNA vaccine. These results demonstrate that bicistronic DNA vaccines containing GM-CSF elicit remarkably potent CD4+ T cell responses and suggest that optimal Th cell priming requires the precise temporal and spatial codelivery of Ag and GM-CSF.
The Receptor for Heat Shock Protein 60 on Macrophages Is Saturable, Specific, and Distinct from Receptors for Other Heat Shock Proteins
Authors: Habich Christiane , Baumgart Karina , Kolb Hubert , Burkart Volker 
Published: April 2014

AbstractPrevious studies have shown that human heat shock protein (hsp) 60 elicits a strong proinflammatory response in cells of the innate immune system with CD14, Toll-like receptor (TLR) 2, and TLR4 as mediators of signaling, but probably not of binding. In the present study, we directly demonstrate binding of hsp60 to the macrophage surface and find the binding receptor for hsp60 different from the previously described common receptor for several other heat shock proteins, including hsp70, hsp90, and gp96. Fluorescence-labeled human hsp60 bound to cell surfaces of the murine macrophage lines J774 A.1 and RAW264.7 and to mouse bone marrow-derived macrophages. By flow cytometry, we could demonstrate for the first time that hsp60 binding to macrophages occurred at submicromolar concentrations, is saturable, and can be competed by unlabeled hsp60, but not by unrelated proteins, thus confirming the classic characteristics of specific ligand-receptor interactions. Binding of hsp60 at 4°C was followed by endocytosis at 37°C. Hsp60 binding to macrophages could not be competed by excess hsp70, hsp90, or gp96, all of which share the α2-macroglobulin receptor as binding site. Hsp60 binding occurred in the absence of surface TLR4. However, no cytokine response was induced by hsp60 in TLR4-deficient macrophages. We conclude that hsp60 binds to a stereo-specific receptor on macrophages, and that different surface molecules are engaged in binding and signal transduction. Furthermore, the binding site for hsp60 is separate from the common receptor for hsp70, hsp90, and gp96, which suggests an independent role of hsp60 as danger Ag and in immunoregulation.
I-κB Kinase β Is Critical for B Cell Proliferation and Antibody Response
Authors: Ren Hong , Schmalstieg Aurelia , Yuan Dorothy , Gaynor Richard B. 
Published: April 2014

AbstractThe NF-κB proteins are critical in the regulation of the immune and inflammatory response. Stimulation of the NF-κB pathway leads to increases in I-κB kinase β (IKKβ) kinase activity to result in the enhanced phosphorylation and degradation of I-κB and the translocation of the NF-κB proteins from the cytoplasm to the nucleus. In this study, a dominant-negative IKKβ mutant expressed from the IgH promoter was used to generate transgenic mice to address the role of IKKβ on B cell function. Although these transgenic mice were defective in activating the NF-κB pathway in B cells, they exhibited no defects in B lymphocyte development or basal Ig levels. However, they exhibited defects in the cell cycle progression and proliferation of B cells in response to treatment with LPS, anti-CD40, and anti-IgM. Furthermore, selective defects in the production of specific Ig subclasses in response to both T-dependent and T-independent Ags were noted. These results suggest that IKKβ is critical for the proliferation of B cells and the control of some aspects of the humoral response.
Migration of Human Hematopoietic Progenitor Cells Across Bone Marrow Endothelium Is Regulated by Vascular Endothelial Cadherin
Authors: van Buul Jaap D. , Voermans Carlijn , van den Berg Veronique , Anthony Eloise C. , Mul Frederik P. J. , van Wetering Sandra , van der Schoot C. Ellen , Hordijk Peter L. 
Published: April 2014

AbstractThe success of stem cell transplantation depends on the ability of i.v. infused stem cells to engraft the bone marrow, a process referred to as homing. Efficient homing requires migration of CD34+ cells across the bone marrow endothelium, most likely through the intercellular junctions. In this study, we show that loss of vascular endothelial (VE)-cadherin-mediated endothelial cell-cell adhesion increases the permeability of monolayers of human bone marrow endothelial cells (HBMECs) and stimulates the transendothelial migration of CD34+ cells in response to stromal cell-derived factor-1α. Stromal cell-derived factor-1α-induced migration was dependent on VCAM-1 and ICAM-1, even in the absence of VE-cadherin function. Cross-linking of ICAM-1 to mimic the leukocyte-endothelium interaction induced actin stress fiber formation but did not induce loss of endothelial integrity, whereas cross-linking of VCAM-1 increased the HBMEC permeability and induced gaps in the monolayer. In addition, VCAM-1-mediated gap formation in HBMEC was accompanied by and dependent on the production of reactive oxygen species. These data suggest that modulation of VE-cadherin function directly affects the efficiency of transendothelial migration of CD34+ cells and that activation of ICAM-1 and, in particular, VCAM-1 plays an important role in this process through reorganization of the endothelial actin cytoskeleton and by modulating the integrity of the bone marrow endothelium through the production of reactive oxygen species.
IL-2 and Related Cytokines Can Promote T Cell Survival by Activating AKT
Authors: Kelly Erin , Won Angela , Refaeli Yosef , Van Parijs Luk 
Published: April 2014

AbstractThe regulated elimination of T cells serves to maintain normal immune function and prevents autoimmune responses. IL-2 family cytokines play an important role in controlling the survival of immature and mature T cells. These molecules activate the protein kinase, AKT/PKB. AKT has been shown to transduce an antiapoptotic signal in numerous cell types. In this study, we show that an active form of AKT can protect T cells from apoptosis following growth factor withdrawal and that IL-2 family cytokines can promote T cell survival by activating this kinase. We also provide evidence that AKT does not block death receptor-mediated killing of lymphocytes. These data suggest that AKT may serve as a common signaling element by which members of the IL-2 family of cytokines promote T cell survival.
Fractalkine Is Expressed by Smooth Muscle Cells in Response to IFN-γ and TNF-α and Is Modulated by Metalloproteinase Activity
Authors: Ludwig Andreas , Berkhout Theo , Moores Kitty , Groot Pieter , Chapman Gayle 
Published: April 2014

Abstract
Fractalkine/CX3C-chemokine ligand 1 is expressed as a membrane-spanning adhesion molecule that can be cleaved from the cell surface to produce a soluble chemoattractant. Within the vasculature, fractalkine is known to be generated by endothelial cells, but to date there are no reports describing its expression by smooth muscle cells (SMC). In this study we demonstrate that IFN-γ and TNF-α, but not IL-1β, cooperate synergistically to induce fractalkine mRNA and protein expression in cultured aortic SMC. We also report the release of functional, soluble fractalkine from the membranes of stimulated SMC. This release is inhibited by the zinc metalloproteinase inhibitor batimastat, resulting in the accumulation of membrane-associated fractalkine on the SMC surface. Therefore, an SMC-derived metalloproteinase activity is involved in fractalkine shedding. While soluble fractalkine present in SMC-conditioned medium is capable of inducing calcium transients in cells expressing the fractalkine receptor (CX3CR1), blocking experiments using neutralizing Abs reveal that it can be inactivated without affecting the chemotactic activity of SMC-conditioned media on monocytes. However, membrane-bound fractalkine plays a major role in promoting adhesion of monocytic cells to activated SMC. This fractalkine-mediated adhesion is further enhanced in the presence of batimastat, indicating that shedding of fractalkine from the cell surface down-regulates the adhesive properties of SMC. Hence, during vascular inflammation, the synergistic induction of fractalkine by IFN-γ and TNF-α together with its metalloproteinase-mediated cleavage may finely control the recruitment of monocytes to SMC within the blood vessel wall.
Peptide Specificity of Thymic Selection of CD4+CD25+ T Cells
Authors: Pacholczyk Rafal , Kraj Piotr , Ignatowicz Leszek 
Published: April 2014

AbstractThe CD4+CD25+ regulatory T cells can be found in the thymus, but their need to undergo positive and negative selection has been questioned. Instead, it has been hypothesized that CD4+CD25+ cells mature following TCR binding to MHC backbone, to low abundant MHC/peptide complexes, or to class II MHC loaded with peripheral autoantigens. In all these circumstances, processes that are distinct from positive and negative selection would govern the provenance of CD4+CD25+ cells in the thymus. By comparing the development of CD4+CD25− and CD4+CD25+ cells in mice expressing class II MHC molecules bound with one or many peptide(s), we show that the CD4+CD25+ cells appear during natural selection of CD4+ T cells. The proportion of CD4+CD25+ cells in the population of CD4+ thymocytes remains constant, and their total number reflects the complexity of selecting class II MHC/peptide complexes. Hence, thymic development of CD4+CD25+ cells does not exclusively depend on the low-density, high-affinity MHC/peptide complexes or thymic presentation of peripheral self-Ags, but, rather, these cells are selected as a portion of the natural repertoire of CD4+ T cells. Furthermore, while resistant to deletion mediated by endogenous superantigen(s), these cells were negatively selected on class II MHC/peptide complexes. We postulate that while the CD4+CD25+ thymocytes are first detectable in the thymic medulla, their functional commitment occurs in the thymic cortex.
Elimination of Porcine Hemopoietic Cells by Macrophages in Mice
Authors: Abe Masahiro , Cheng Jane , Qi Jin , Glaser Roseann M. , Thall Aron D. , Sykes Megan , Yang Yong-Guang 
Published: April 2014

Abstract
The difficulty in achieving donor hemopoietic engraftment across highly disparate xenogeneic species barriers poses a major obstacle to exploring xenograft tolerance induction by mixed chimerism. In this study, we observed that macrophages mediate strong rejection of porcine hemopoietic cells in mice. Depletion of macrophages with medronate-encapsulated liposomes (M-liposomes) markedly improved porcine chimerism, and early chimerism in particular, in sublethally irradiated immunodeficient and lethally irradiated immunocompetent mice. Although porcine chimerism in the peripheral blood and spleen of M-liposome-treated mice rapidly declined after macrophages had recovered and became indistinguishable from controls by wk 5 post-transplant, the levels of chimerism in the marrow of these mice remained higher than those in control recipients at 8 wks after transplant. These results suggest that macrophages that developed in the presence of porcine chimerism were not adapted to the porcine donor and that marrow-resident macrophages did not phagocytose porcine cells. Moreover, M-liposome treatment had no effect on the survival of porcine PBMC injected into the recipient peritoneal cavity, but was essential for the migration and relocation of these cells into other tissues/organs, such as spleen, bone marrow, and peripheral blood. Together, our results suggest that murine reticuloendothelial macrophages, but not those in the bone marrow and peritoneal cavity, play a significant role in the clearance of porcine hemopoietic cells in vivo. Because injection of M-liposomes i.v. mainly depletes splenic macrophages and liver Kupffer cells, the spleen and/or liver are likely the primary sites of porcine cell clearance in vivo.
The Pre-B Cell Receptor Signaling for Apoptosis Is Negatively Regulated by FcγRIIB
Authors: Kato Ibuki , Takai Toshiyuki , Kudo Akira 
Published: April 2014

AbstractMany studies have shown that FcγRIIB is a negative regulator of B cell receptor signaling, and even though FcγRIIB is expressed through all developmental stages of the B cell lineage, its involvement in pre-B cell receptor (pre-BCR) signaling has not been examined. To investigate FcγRIIB function at the pre-B cell stage, we have established pre-BCR positive pre-B cell lines from normal mice and FcγRIIB-deficient mice, named PreBR and Fcγ−/−PreBR, respectively. These cell lines are able to differentiate into immature B cells in vitro by removal of IL-7. In PreBR, apoptosis was moderately induced by F(ab′)2 anti-μ Ab, but not by intact anti-μ Ab. Phosphorylation of SH2-containing inositol 5-phosphatase (SHIP) and Dok, which are involved in FcγRIIB signaling, was induced by anti-μ cross-linking in PreBR. In contrast, apoptosis was strongly induced by both the F(ab′)2 and intact anti-μ Abs in Fcγ−/−PreBR, and the level of phosphorylation of SHIP or Dok was much lower in Fcγ−/−PreBR than those observed in PreBR. Restoration of FcγRIIB to Fcγ−/−PreBR followed by anti-μ cross-linking blocked severe apoptosis, and up-regulated SHIP and Dok phosphorylation. The results demonstrate that FcγRIIB negatively regulates pre-BCR-mediated signaling for apoptosis.
A Genetic Determinant That Specifically Regulates the Frequency of Hematopoietic Stem Cells
Authors: Morrison Sean J. , Qian Dalong , Jerabek Libuse , Thiel Bonnie A. , Park In-Kyung , Ford Preston S. , Kiel Mark J. , Schork Nicholas J. , Weissman Irving L. , Clarke Michael F. 
Published: April 2014

Abstract
The regulation of hematopoietic stem cell (HSC) homeostasis is not well understood. We screened for genetic polymorphisms that were linked to differences between mouse strains in the numbers of long-term reconstituting HSCs or restricted progenitors in the bone marrow. AKR/J mice had significantly higher frequencies and numbers of both HSCs and restricted progenitors in their bone marrow than C57BL/Ka-Thy-1.1 mice. The C57BL/Ka-Thy-1.1 alleles were partially dominant. A locus on chromosome 17, including the H-2 complex, was significantly linked to the frequency of long-term self-renewing HSCs but showed no evidence of linkage to the frequency of restricted progenitors. Conversely, a chromosome 1 locus exhibited suggestive linkage to restricted progenitor frequencies but was not linked to HSC frequency. This demonstrates that there are distinct genetic determinants of the frequencies of HSCs and restricted progenitors in vivo. The AKR/J chromosome 17 locus was not sufficient to increase HSC frequencies when bred onto a C57BL background. This suggests that to affect HSC frequencies, the product(s) of this locus likely depend on interactions with unlinked modifying loci.
The BCR/ABL Transgene Causes Abnormal NK Cell Differentiation and Can Be Found in Circulating NK Cells of Advanced Phase Chronic Myelogenous Leukemia Patients
Authors: Nakajima Hikaru , Zhao Robert , Lund Troy C. , Ward Jeanne , Dolan Michelle , Hirsch Betsy , Miller Jeffrey S. 
Published: April 2014

Abstract
NK cells from the blood of chronic myelogenous leukemia (CML) patients are progressively decreased in number as the disease progresses from chronic phase to blast crisis. We hypothesize that BCR/ABL may be directly responsible by interfering with NK cell differentiation. CD34+HLA-DR+ cells from CML patients were studied for their capacity to differentiate into NK cells. The NK cell cloning frequency was significantly decreased from CML CD34+HLA-DR+ cells compared with cells from normal donors, yet CD34+HLA-DR+ cells gave rise to BCR/ABL+ NK cells in some patients. This finding prompted us to further investigate circulating NK cells from the blood of CML patients. CD56+CD3− NK cells were sorted from CML patients and examined by fluorescence in situ hybridization (FISH). In contrast to chronic phase CML, significant numbers of NK cells from advanced phase CML patients were BCR/ABL+, whereas T cells were always BCR/ABL− regardless of the disease stage. To test the effects of BCR/ABL as the sole genetic abnormality, BCR/ABL was transduced into umbilical cord blood CD34+ cells, and NK development was studied. p210-enhanced green fluorescence protein-transduced cells gave rise to significantly decreased numbers of NK cells compared with enhanced green fluorescence protein transduction alone. In addition, the extrinsic addition of BCR/ABL-transduced autologous CD34+ cells suppressed the NK cell differentiation of normal umbilical cord blood CD34+CD38− cells. This study provides the first evidence that BCR/ABL is responsible for the altered differentiation of NK cells and that the NK cell lineage can be involved with the malignant clone in advanced stage CML.