bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Role of Rearrangement at the Second Ig Heavy Chain Locus in Maintaining B Cell Tolerance to DNA
Authors: Liu Yang , Li Lisa , Mohan Chandra 
Published: April 2014

Abstract
In recently generated B6.56R anti-DNA autoantibody-transgenic mice, it was noted that a substantial fraction of the B cells that had avoided DNA reactivity had done so through the rearrangement and usage of the endogenous, nontargeted H chain (HC) allele. This suggested that rearrangement at the second HC locus might be an important mechanism through which self-reactive B cells might successfully revise their initial Ag specificity. To test the importance of this mechanism in B cell tolerance, we generated B6.56R/56R mice that possessed the 56R anti-DNA H chain transgene inserted into both HC loci. These transgenic homozygotes developed higher titers of anti-DNA Abs, with an expanded population of B220lowMHC class IIlow B cells, enriched for CD21lowCD23low preplasmablasts. The analysis of hybridomas from these mice revealed that the only avenue by which these B cells could avoid DNA reactivity was through the use of the editor L chains, Vk20 or Vk21. Hence, in addition to LC editing, rearrangement and usage of the second HC locus/allele constitutes an important safety valve for B cells the primary BCR of which confers DNA reactivity. In contrast to these tolerance mechanisms, editing the first rearranged HC locus (through HC replacement) and somatic mutations appear to be less frequently used to edit/revise self-reactive B cells.
Presence of Suppressor HIV-Specific CD8+ T Cells Is Associated with Increased PD-1 Expression on Effector CD8+ T Cells
Authors: Elrefaei Mohamed , Baker Chris A. R. , Jones Norman G. , Bangsberg David R. , Cao Huyen 
Published: April 2014

Abstract
Mechanisms leading to the observed immune dysregulation in HIV-1 infection are not well understood. HIV-specific IL-10-positive CD8+ T cells are increased in advanced HIV disease. We have previously reported that Gag-specific IL-10-positive CD8+ T cells suppressed cytolysis. In this study we describe the suppressive effect of Nef-specific IL-10-positive CD8+ T cells. Interestingly, simultaneous removal of both Gag- and Nef-specific IL-10-positive CD8+ T cells led to higher HIV-specific cytolysis compared with the removal of Nef-specific IL-10-positive CD8+ T cells alone. We also examined the level of programmed cell death-1 (PD-1) as a measure of immune dysfunction in association with IL-10-positive suppressor CD8+ T cells. The level of PD-1 expression on CD107-positive effector CD8+ T cells was significantly increased when IL-10-positive suppressor CD8+ T cells were present (p &lt; 0.05). Our results suggest that IL-10-positive suppressor CD8+ T cells contribute to the immune dysfunction observed in advanced HIV infection and that the concomitant presence of multiple IL-10-positive CD8+ T cell populations may have an additive suppressive effect.
The Innate NK Cells, Allograft Rejection, and a Key Role for IL-15
Authors: Kroemer Alexander , Xiao Xiang , Degauque Nicolas , Edtinger Karoline , Wei Haiming , Demirci Gulcin , Li Xian Chang 
Published: April 2014

Abstract
Transplant rejection is mediated primarily by adaptive immune cells such as T cells and B cells. The T and B cells are also responsible for the specificity and memory of the rejection response. However, destruction of allografts involves many other cell types including cells in the innate immune system. As the innate immune cells do not express germline-encoded cell surface receptors that directly recognize foreign Ags, these cells are thought to be recruited by T cells to participate in the rejection response. In this study, we examined the alloreactivity of the innate NK cells in Rag−/− mice using a stringent skin transplant model and found that NK cells at a resting state readily reject allogeneic cells, but not the skin allografts. We also found that IL-15, when preconjugated to its high affinity IL-15Rα-chain, is remarkably potent in stimulating NK cells in vivo, and NK cells stimulated by IL-15 express an activated phenotype and are surprisingly potent in mediating acute skin allograft rejection in the absence of any adaptive immune cells. Furthermore, NK cell-mediated graft rejection does not show features of memory responses. Our data demonstrate that NK cells are potent alloreactive cells when fully activated and differentiated under certain conditions. This finding may have important clinical implications in models of transplantation and autoimmunity.
Comprehensive Gene Expression Profiling of Peyer’s Patch M Cells, Villous M-Like Cells, and Intestinal Epithelial Cells
Authors: Terahara Kazutaka , Yoshida Masato , Igarashi Osamu , Nochi Tomonori , Pontes Gemilson Soares , Hase Koji , Ohno Hiroshi , Kurokawa Shiho , Mejima Mio , Takayama Naoko , Yuki Yoshikazu , Lowe Anson W. , Kiyono Hiroshi 
Published: April 2014

Abstract
Separate populations of M cells have been detected in the follicle-associated epithelium of Peyer’s patches (PPs) and the villous epithelium of the small intestine, but the traits shared by or distinguishing the two populations have not been characterized. Our separate study has demonstrated that a potent mucosal modulator cholera toxin (CT) can induce lectin Ulex europaeus agglutinin-1 and our newly developed M cell-specific mAb NKM 16-2-4-positive M-like cells in the duodenal villous epithelium. In this study, we determined the gene expression of PP M cells, CT-induced villous M-like cells, and intestinal epithelial cells isolated by a novel approach using FACS. Additional mRNA and protein analyses confirmed the specific expression of glycoprotein 2 and myristoylated alanine-rich C kinase substrate (MARCKS)-like protein by PP M cells but not CT-induced villous M-like cells. Comprehensive gene profiling also suggested that CT-induced villous M-like cells share traits of both PP M cells and intestinal epithelial cells, a finding that is supported by their unique expression of specific chemokines. The genome-wide assessment of gene expression facilitates discovery of M cell-specific molecules and enhances the molecular understanding of M cell immunobiology.
Myeloid-Derived Suppressor Cells Accumulate in Kidney Allograft Tolerance and Specifically Suppress Effector T Cell Expansion
Authors: Dugast Anne-Sophie , Haudebourg Thomas , Coulon Flora , Heslan Michèle , Haspot Fabienne , Poirier Nicolas , Vuillefroy de Silly Romain , Usal Claire , Smit Helga , Martinet Bernard , Thebault Pamela , Renaudin Karine , Vanhove Bernard 
Published: April 2014

AbstractThe immune tolerance to rat kidney allografts induced by a perioperative treatment with anti-CD28 Abs is associated with a severe unresponsiveness of peripheral blood cells to donor Ags. In this model, we identified an accumulation in the blood of CD3−class II−CD11b+CD80/86+ plastic-adherent cells that additionally expressed CD172a as well as other myeloid markers. These cells were able to inhibit proliferation, but not activation, of effector T cells and to induce apoptosis in a contact-dependent manner. Their suppressive action was found to be under the control of inducible NO synthase, an enzyme also up-regulated in tolerated allografts. Based on these features, these cells can be defined as myeloid-derived suppressor cells (MDSC). Interestingly, CD4+CD25highFoxP3+ regulatory T cells were insensitive in vitro to MDSC-mediated suppression. Although the adoptive transfer of MDSC failed to induce kidney allograft tolerance in recently transplanted recipients, the maintenance of tolerance after administration of anti-CD28 Abs was found to be dependent on the action of inducible NO synthase. These results suggest that increased numbers of MDSC can inhibit alloreactive T cell proliferation in vivo and that these cells may participate in the NO-dependent maintenance phase of tolerance.
Central Memory CD8+ T Cells Appear to Have a Shorter Lifespan and Reduced Abundance as a Function of HIV Disease Progression
Authors: Ladell Kristin , Hellerstein Marc K. , Cesar Denise , Busch Robert , Boban Drina , McCune Joseph M. 
Published: April 2014

Abstract
Progressive HIV disease has been associated with loss of memory T cell responses to Ag. To better characterize and quantify long-lived memory T cells in vivo, we have refined an in vivo labeling technique to study the kinetics of phenotypically distinct, low-frequency CD8+ T cell subpopulations in humans. HIV-negative subjects and antiretroviral-untreated HIV-infected subjects in varying stages of HIV disease were studied. After labeling the DNA of dividing cells with deuterated water (2H2O), 2H-label incorporation and die-away kinetics were quantified using a highly sensitive FACS/mass spectrometric method. Two different populations of long-lived memory CD8+ T cells were identified in HIV-negative subjects: CD8+CD45RA−CCR7+CD28+ central memory (TCM) cells expressing IL-7Rα and CD8+CD45RA+CCR7−CD28− RA effector memory (TEMRA) cells expressing CD57. In pilot studies in HIV-infected subjects, TCM cells appeared to have a shorter half-life and reduced abundance, particularly in those with high viral loads; TEMRA cells, by contrast, retained a long half-life and accumulated in the face of progressive HIV disease. These data are consistent with the hypothesis that IL-7Rα+ TCM cells represent true memory CD8+ T cells, the loss of which may be responsible in part for the progressive loss of T cell memory function during progressive HIV infection.
Chronic Estradiol Administration In Vivo Promotes the Proinflammatory Response of Macrophages to TLR4 Activation: Involvement of the Phosphatidylinositol 3-Kinase Pathway
Authors: Calippe Bertrand , Douin-Echinard Victorine , Laffargue Muriel , Laurell Henrik , Rana-Poussine Vanessa , Pipy Bernard , Guéry Jean-Charles , Bayard Francis , Arnal Jean-François , Gourdy Pierre 
Published: April 2014

Abstract
Short-term exposure to 17β-estradiol (E2) in vitro has been reported to decrease the production of proinflammatory cytokines by LPS-activated macrophages through estrogen receptor α (ERα)-dependent activation of the PI3K pathway. In the present study, we confirm that in vitro exposure of mouse peritoneal macrophages to E2 enhanced Akt phosphorylation and slightly decreased LPS-induced cytokine production. In striking contrast, we show that chronic administration of E2 to ovariectomized mice markedly increases the expression of IL-1β, IL-6, IL-12p40, and inducible NO synthase by resident peritoneal macrophages in response to LPS ex vivo. These results clearly indicate that short-term E2 treatment in vitro does not predict the long-term effect of estrogens in vivo on peritoneal macrophage functions. We show that this in vivo proinflammatory effect of E2 was mediated through ERα. Although the expression of components of the LPS-recognition complex remained unchanged, we provided evidences for alterations of the TLR4 signaling pathway in macrophages from E2-treated mice. Indeed, E2 treatment resulted in the inhibition of PI3K activity and Akt phosphorylation in LPS-activated macrophages, whereas NF-κB p65 transcriptional activity was concomitantly increased. Incubation of macrophages with the PI3K inhibitor wortmanin enhanced proinflammatory cytokine gene expression in response to TLR4 activation, and abolishes the difference between cells from placebo- or E2-treated mice, demonstrating the pivotal role of the PI3K/Akt pathway. We conclude that the macrophage activation status is enhanced in vivo by E2 through ERα and, at least in part, by the down-modulation of the PI3K/Akt pathway, thereby alleviating this negative regulator of TLR4-signaling.
T-Bet Plays a Key Role in NK-Mediated Control of Melanoma Metastatic Disease
Authors: Werneck Miriam B. F. , Lugo-Villarino Geanncarlo , Hwang Eun Sook , Cantor Harvey , Glimcher Laurie H. 
Published: April 2014

AbstractAntitumor responses depend on type 1 immunity, which is severely impaired in mice deficient for the T-box expressed in T cells (T-bet) transcription factor. Both T-bet-deficient (T-bet−/−) NK and CTL show defective function, which can be overcome by strong stimuli due to the expression of eomesodermin, another member of the T-box family. The effective response from T-bet−/− mice to viral infection and tumor initiation corroborates with these findings. However, T-bet−/− animals fail to control cancer metastasis and are, therefore, highly susceptible to tumor spread. The mechanism of T-bet-dependent resistance to metastatic disease is not known. In this study, we show that T-bet plays a role in inhibiting cancer metastasis by regulating the longevity and function of NK cells. Our data demonstrate that the absence of a proper innate immune response driven by NK cells in T-bet−/− mice precludes the initiation of a potent adaptive response to tumors. Adoptive transfer of wild-type activated NK cells protects T-bet−/− animals after melanoma challenge showing that reconstitution of the NK compartment in these mice is sufficient to mediate a significant reduction in tumor burden. Transfer of T-bet−/− A-NK cells fails to do so, due to their reduced in vivo survival, inefficient lysis of cancer cells, and poor IFN-γ production. Taken together, these results show for the first time an irreplaceable role for T-bet in the NK-mediated cross-talk between innate and adaptive immune responses to metastatic disease.
Blunted IgE-Mediated Activation of Mast Cells in Mice Lacking the Ca2+-Activated K+ Channel KCa3.1
Authors: Shumilina Ekaterina , Lam Rebecca S. , Wölbing Florian , Matzner Nicole , Zemtsova Irina M. , Sobiesiak Malgorzata , Mahmud Hasan , Sausbier Ulrike , Biedermann Tilo , Ruth Peter , Sausbier Matthias , Lang Florian 
Published: April 2014

AbstractMast cell stimulation by Ag is followed by the opening of Ca2+-activated K+ channels, which participate in the orchestration of mast cell degranulation. The present study has been performed to explore the involvement of the Ca2+-activated K+ channel KCa3.1 in mast cell function. To this end mast cells have been isolated and cultured from the bone marrow (bone marrow-derived mast cells (BMMCs)) of KCa3.1 knockout mice (KCa3.1−/−) and their wild-type littermates (KCa3.1+/+). Mast cell number as well as in vitro BMMC growth and CD117, CD34, and FcεRI expression were similar in both genotypes, but regulatory cell volume decrease was impaired in KCa3.1−/− BMMCs. Treatment of the cells with Ag, endothelin-1, or the Ca2+ ionophore ionomycin was followed by stimulation of Ca2+-activated K+ channels and cell membrane hyperpolarization in KCa3.1+/+, but not in KCa3.1−/− BMMCs. Upon Ag stimulation, Ca2+ entry but not Ca2+ release from intracellular stores was markedly impaired in KCa3.1−/− BMMCs. Similarly, Ca2+ entry upon endothelin-1 stimulation was significantly reduced in KCa3.1−/− cells. Ag-induced release of β-hexosaminidase, an indicator of mast cell degranulation, was significantly smaller in KCa3.1−/− BMMCs compared with KCa3.1+/+ BMMCs. Moreover, histamine release upon stimulation of BMMCs with endothelin-1 was reduced in KCa3.1−/− cells. The in vivo Ag-induced decline in body temperature revealed that IgE-dependent anaphylaxis was again significantly (by ∼50%) blunted in KCa3.1−/− mice. In conclusion, KCa3.1 is required for Ca2+-activated K+ channel activity and Ca2+-dependent processes such as endothelin-1- or Ag-induced degranulation of mast cells, and may thus play a critical role in anaphylactic reactions.
Essential Roles for the Tec Family Kinases Tec and Btk in M-CSF Receptor Signaling Pathways That Regulate Macrophage Survival
Authors: Melcher Martin , Unger Bernd , Schmidt Uwe , Rajantie Iiro A. , Alitalo Kari , Ellmeier Wilfried 
Published: April 2014

Abstract
Tec family kinases have important roles in lymphocytes; however, little is known about their function in monocytes/macrophages. In this study we report that Tec family kinases are essential for M-CSF (M-CSF)-induced signaling pathways that regulate macrophage survival. Compared with wild-type bone marrow-derived macrophage (BMM) cultures, Tec−/−Btk−/− BMM cultures displayed increased cell death that correlated with a severe drop in macrophage numbers. In addition, macrophages deficient in either Tec or Btk showed expression and activation of caspase-11. Elucidation of M-CSF receptor (M-CSFR) signaling pathways revealed that the total tyrosine phosphorylation pattern upon M-CSF stimulation was altered in Tec−/−Btk−/− macrophages despite normal expression and phosphorylation of the M-CSFR. Further, Tec and Btk are required for proper expression of the GM-CSF receptor α (GM-CSFRα) chain in macrophages but not dendritic cells, implicating Tec family kinases in the lineage-specific regulation of GM-CSFRα expression. Taken together, our study shows that Tec and Btk regulate M-CSFR signaling-induced macrophage survival and provides a novel link between Tec family kinases and the regulation of caspase-11 and GM-CSFRα expression.
Host T Cells Are the Main Producers of IL-17 within the Central Nervous System during Initiation of Experimental Autoimmune Encephalomyelitis Induced by Adoptive Transfer of Th1 Cell Lines
Authors: Lees Jason R. , Iwakura Yoichiro , Russell John H. 
Published: April 2014

AbstractExperimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis, has long been thought to be mediated by Th1 CD4+ T cells. Using adoptive transfer techniques, transfer of CNS specific Th1 T cells was sufficient to induce EAE in naive mice. However, recent studies found a vital role for IL-17 in induction of EAE. These studies suggested that a fraction of IL-17-producing T cells that contaminate Th1 polarized cell lines are largely responsible for initiation of EAE. In this study, we tracked the appearance and cytokine production capacity of adoptively transferred cells within the CNS of mice throughout EAE disease. IL-17-producing, adoptively transferred cells were not enriched over the low percentages present in vitro. Thus, there was no selective recruitment and/or preferential proliferation of adoptively transferred IL-17-producing cells during the induction of EAE. Instead a large number of CNS infiltrating host T cells in mice with EAE were capable of producing IL-17 following ex vivo stimulation. The IL-17-producing T cells contained both αβ and γδ TCR+ T cells with a CD4+CD8− or CD4−CD8− phenotype. These cells concentrated within the CNS within 3 days of adoptive transfer, and appeared to play a role in EAE induction as adoptive transfer of Th1 lines derived from wild-type mice into IL-17-deficient mice induced reduced EAE clinical outcomes. This study demonstrates that an encephalitogenic Th1 cell line induces recruitment of host IL-17-producing T cells to the CNS during the initiation of EAE and that these cells contribute to the incidence and severity of disease.
CD47 Expression on T Cell Is a Self-Control Negative Regulator of Type 1 Immune Response
Authors: Bouguermouh Salim , Van Vu Quang , Martel Julie , Gautier Patrick , Rubio Manuel , Sarfati Marika 
Published: April 2014

Abstract
The cytokine milieu and dendritic cells (DCs) direct Th1 development. Yet, the control of Th1 polarization by T cell surface molecules remains ill-defined. We here report that CD47 expression on T cells serves as a self-control mechanism to negatively regulate type 1 cellular and humoral immune responses in vivo. Th2-prone BALB/c mice that lack CD47 (CD47−/−) displayed a Th1-biased Ab profile at steady state and after immunization with soluble Ag. CD47−/− mice mounted a T cell-mediated exacerbated and sustained contact hypersensitivity (CHS) response. After their adoptive transfer to naive CD47-deficient hosts 1 day before immunization with soluble Ag, CD47−/− as compared with CD47+/+CD4+ transgenic (Tg) T cells promoted the deviation of Ag-specific T cell responses toward Th1 that were characterized by a high IFN-γ:IL-4 cytokine ratio. Although selective CD47 deficiency on DCs led to increased IL-12p70 production, CD47−/−Tg T cells produced more IFN-γ and displayed higher T-bet expression than CD47+/+ Tg T cells in response to OVA-loaded CD47−/− DCs. CD47 as part of the host environment has no major contribution to the Th1 polarization responses. We thus identify the CD47 molecule as a T cell-negative regulator of type 1 responses that may limit unwanted collateral damage to maximize protection and minimize host injury.
Full Development of Th2 Immunity Requires Both Innate and Adaptive Sources of CD154
Authors: Jenkins Stephen J. , Perona-Wright Georgia , MacDonald Andrew S. 
Published: April 2014

Abstract
The CD40-CD154 interaction is critical for Th2 response generation during helminth infection and following immunization with helminth-conditioned dendritic cells, yet the key cellular sources of these molecules have still to be defined in vivo. In this study, we demonstrate that the requirement for CD40 expression during murine Th2 response induction is restricted exclusively to the Ag-bearing dendritic cells. In contrast, development of full Th2 immunity required CD154 expression on multiple populations. In this respect, optimal production of IL-5, IL-10, and IL-13 was dependent upon CD154 expression by both CD4+ T cells and non-lymphoid cells. IL-4 production had less stringent costimulatory requirements, with expression of CD154 on either non-lymphoid cells or T cells alone being sufficient to enable production of this archetypal Th2 cytokine. Disparities in CD154 requirements for T cell and B cell responses were revealed during experimental schistosomiasis where, even in the face of robust Th2 generation, B cell class-switching was entirely dependent upon expression of CD154 by the lymphoid compartment. These data help define the costimulatory interactions that occur during the generation of Th2 immunity, and challenge the widely held view that CD154 expressing T cells are the sole contributors in this process.
Induction of Exosome Release in Primary B Cells Stimulated via CD40 and the IL-4 Receptor
Authors: Saunderson Sarah C. , Schuberth Petra C. , Dunn Amy C. , Miller Lilija , Hock Barry D. , MacKay Philippa A. , Koch Norbert , Jack Ralph W. , McLellan Alexander D. 
Published: April 2014

Abstract
Exosomes are lipid-bound nanovesicles formed by inward budding of the endosomal membrane and released following fusion of the endosomal limiting membrane with the plasma membrane. We show here that primary leukocytes do not release exosomes unless subjected to potent activation signals, such as cytokine or mitogen stimulation. In particular, high levels of exosomes were released when murine splenic B cells were stimulated via CD40 and the IL-4 receptor. This property was shared by B cells from different anatomic locations, as newly formed, marginal zone and follicular B cells were capable of secreting exosomes upon CD40/IL-4 triggering. B cell exosomes expressed high levels of MHC class I, MHC class II, and CD45RA (B220), as well as components of the BCR complex, namely, surface Ig, CD19, and the tetraspanins CD9 and CD81. Ig on the plasma membrane of primary B cells was targeted to the exosome pathway, demonstrating a link between the BCR and this exocytic pathway. IgD and IgM were the predominant Ig isotypes associated with CD40/IL-4 elicited exosomes, though other isotypes (IgA, IgG1, IgG2a/2b, and IgG3) were also detected. Together, these results suggest that exosome release is not R constitutive activity of B cells, but may be induced following cell: cell signaling.