搜索结果: 'gmp t cell activator'

Bright/Arid3a has been characterized both as an activator of immunoglobulin heavy-chain transcription and as a proto-oncogene. Although Bright expression is highly B lineage stage restricted in adult mice,its expression in the earliest identifiable hematopoietic stem cell (HSC) population suggests that Bright might have additional functions. We showed that textgreater99% of Bright(-/-) embryos die at midgestation from failed hematopoiesis. Bright(-/-) embryonic day 12.5 (E12.5) fetal livers showed an increase in the expression of immature markers. Colony-forming assays indicated that the hematopoietic potential of Bright(-/-) mice is markedly reduced. Rare survivors of lethality,which were not compensated by the closely related paralogue Bright-derived protein (Bdp)/Arid3b,suffered HSC deficits in their bone marrow as well as B lineage-intrinsic developmental and functional deficiencies in their peripheries. These include a reduction in a natural antibody,B-1 responses to phosphocholine,and selective T-dependent impairment of IgG1 class switching. Our results place Bright/Arid3a on a select list of transcriptional regulators required to program both HSC and lineage-specific differentiation. View Publication

We have previously shown that a granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin-15 (IL-15) 'fusokine' (GIFT15) exerts immune suppression via aberrant signaling through the IL-15 receptor on lymphomyeloid cells. We show here that ex vivo GIFT15 treatment of mouse splenocytes generates suppressive regulatory cells of B cell ontogeny (hereafter called GIFT15 B(reg) cells). Arising from CD19+ B cells,GIFT15 B(reg) cells express major histocompatibility complex class I (MHCI) and MHCII,surface IgM and IgD,and secrete IL-10,akin to previously described B10 and T2-MZP B(reg) cells,but lose expression of the transcription factor PAX5,coupled to upregulation of CD138 and reciprocal suppression of CD19. Mice with experimental autoimmune encephalomyelitis went into complete remission after intravenous infusion of GIFT15 B(reg) cells paralleled by suppressed neuroinflammation. The clinical effect was abolished when GIFT15 B(reg) cells were derived from mmicroMT (lacking B cells),MHCII-knockout,signal transducer and activator of transcription-6 (STAT-6)-knockout,IL-10-knockout or allogeneic splenocytes,consistent with a pivotal role for MHCII and IL-10 by sygeneic B cells for the observed therapeutic effect. We propose that autologous GIFT15 B(reg) cells may serve as a new treatment for autoimmune ailments. View Publication

Class switch DNA recombination (CSR) is central to the maturation of the Ab response because it diversifies Ab effector functions. Like somatic hypermutation,CSR requires activation-induced cytidine deaminase (AID),whose expression is restricted to B cells,as induced by CD40 engagement or dual TLR-BCR engagement (primary CSR-inducing stimuli). By constructing conditional knockout Igh(+/C)γ(1-cre)Rab7(fl/fl) mice,we identified a B cell-intrinsic role for Rab7,a small GTPase involved in intracellular membrane functions,in mediating AID induction and CSR. Igh(+/C)γ(1-cre)Rab7(fl/fl) mice displayed normal B and T cell development and were deficient in Rab7 only in B cells undergoing Igh(C)γ(1-cre) Iγ1-Sγ1-Cγ1-cre transcription,as induced--like Igh germline Iγ1-Sγ1-Cγ1 and Iε-Sε-Cε transcription--by IL-4 in conjunction with a primary CSR-inducing stimulus. These mice could not mount T-independent or T-dependent class-switched IgG1 or IgE responses while maintaining normal IgM levels. Igh(+/C)γ(1-cre)Rab7(fl/fl) B cells showed,in vivo and in vitro,normal proliferation and survival,normal Blimp-1 expression and plasma cell differentiation,as well as intact activation of the noncanonical NF-κB,p38 kinase,and ERK1/2 kinase pathways. They,however,were defective in AID expression and CSR in vivo and in vitro,as induced by CD40 engagement or dual TLR1/2-,TLR4-,TLR7-,or TLR9-BCR engagement. In Igh(+/C)γ(1-cre)Rab7(fl/fl) B cells,CSR was rescued by enforced AID expression. These findings,together with our demonstration that Rab7-mediated canonical NF-κB activation,as critical to AID induction,outline a novel role of Rab7 in signaling pathways that lead to AID expression and CSR,likely by promoting assembly of signaling complexes along intracellular membranes. View Publication

Brucella is a facultative intracellular pathogen and the etiological agent of brucellosis. In some cases,human brucellosis results in a persistent infection that may reactivate years after the initial exposure. The mechanisms by which the parasite evades clearance by the immune response to chronically infect its host are unknown. We recently demonstrated that dendritic cells (DCs),which are critical components of adaptive immunity,are highly susceptible to Brucella infection and are a preferential niche for the development of the bacteria. Here,we report that in contrast to several intracellular bacteria,Brucella prevented the infected DCs from engaging in their maturation process and impaired their capacities to present antigen to naïve T cells and to secrete interleukin-12. Moreover,Brucella-infected DCs failed to release tumor necrosis factor alpha (TNF-alpha),a defect involving the bacterial protein Omp25. Exogenous TNF-alpha addition to Brucella-infected DCs restored cell maturation and allowed them to present antigens. Two avirulent mutants of B. suis,B. suis bvrR and B. suis omp25 mutants,which do not express the Omp25 protein,triggered TNF-alpha production upon DC invasion. Cells infected with these mutants subsequently matured and acquired the ability to present antigens,two properties which were dramatically impaired by addition of anti-TNF-alpha antibodies. In light of these data,we propose a model in which virulent Brucella alters the maturation and functions of DCs through Omp25-dependent control of TNF-alpha production. This model defines a specific evasion strategy of the bacteria by which they can escape the immune response to chronically infect their host. View Publication

Structural bone allografts are widely used in the clinic to treat critical sized bone defects,despite lacking the osteoinductive characteristics of live autografts. To address this,we generated revitalized structural allografts wrapped with mesenchymal stem/progenitor cell (MSC) sheets,which were produced by expanding primary syngenic bone marrow derived cells on temperature-responsive plates,as a tissue-engineered periosteum. In vitro assays demonstrated maintenance of the MSC phenotype in the sheets,suggesting that short-term culturing of MSC sheets is not detrimental. To test their efficacy in vivo,allografts wrapped with MSC sheets were transplanted into 4-mm murine femoral defects and compared to allografts with direct seeding of MSCs and allografts without cells. Evaluations consisted of X-ray plain radiography,3D microCT,histology,and biomechanical testing at 4- and 6-weeks post-surgery. Our findings demonstrate that MSC sheets induce prolonged cartilage formation at the graft-host junction and enhanced bone callus formation,as well as graft-host osteointegration. Moreover,a large periosteal callus was observed spanning the allografts with MSC sheets,which partially mimics live autograft healing. Finally,biomechanical testing showed a significant increase in the structural and functional properties of MSC sheet grafted femurs. Taken together,MSC sheets exhibit enhanced osteogenicity during critical sized bone defect repair,demonstrating the feasibility of this tissue engineering solution for massive allograft healing. View Publication

The B cell-activating factor of the TNF family receptor (BAFF-R),encoded by the TNFRSF13C gene,is critically important for transitional B cell survival to maturity. Thus,ligation of BAFF-R by BAFF delivers a potent survival signal. Reports implicating the BAFF/BAFF-R signaling axis in the pathogenesis of autoimmune human diseases and B lineage malignancies have largely prompted studies focusing on BAFF expression; however,there is an equally critical need to better understand BAFF-R expression. Initial BAFF-R expression,although characterized in murine B cells,has not yet been reported in human B lymphopoiesis. In this study,we first demonstrate that BAFF-R expression is absent from early precursors and is acquired by bone marrow B cells newly expressing the BCR. We next focused on identifying the specific genomic region that controls BAFF-R expression in mature B cells (i.e.,the TNFRSF13C promoter). To accomplish this,we used in silico tools examining interspecies genomic conservation in conjunction with reporter constructs transfected into malignant B and plasma cell lines. DNase protection assays using nuclear extracts from BAFF-R-expressing cells suggested potential regulatory sites,which allowed the generation of EMSA probes that bound NFs specific to BAFF-R-expressing cells. With a more stringent analysis of interspecies homology,these assays identified a site at which a single nucleotide substitution could distinctly impact promoter activity. Finally,chromatin immunoprecipitation assays revealed the in vivo binding of the specific transcription factor c-Rel to the most proximal genomic region,and c-Rel small interfering RNA transfections in BAFF-R-expressing lines demonstrated a coincident knockdown of both c-Rel and BAFF-R mRNA. View Publication

Symptomatic dengue virus infection ranges in disease severity from an influenza-like illness to life-threatening shock. One model of the mechanism underlying severe disease proposes that weakly neutralizing,dengue serotype cross-reactive antibodies induced during a primary infection facilitate virus entry into Fc receptor-bearing cells during a subsequent secondary infection,increasing viral replication and the release of cytokines and vasoactive mediators,culminating in shock. This process has been termed antibody-dependent enhancement of infection and has significantly hindered vaccine development. Much of our understanding of this process has come from studies using mouse monoclonal antibodies (MAbs); however,antibody responses in mice typically exhibit less complexity than those in humans. A better understanding of the humoral immune response to natural dengue virus infection in humans is sorely needed. Using a high-efficiency human hybridoma technology,we isolated 37 hybridomas secreting human MAbs to dengue viruses from 12 subjects years or even decades following primary or secondary infection. The majority of the human antibodies recovered were broadly cross-reactive,directed against either envelope or premembrane proteins,and capable of enhancement of infection in vitro; few exhibited serotype-specific binding or potent neutralizing activity. Memory B cells encoding enhancing antibodies predominated in the circulation,even two or more decades following infection. Mapping the epitopes and activity of naturally occurring dengue antibodies should prove valuable in determining whether the enhancing and neutralizing activity of antibodies can be separated. Such principles could be used in the rational design of vaccines that enhance the induction of neutralizing antibodies,while lowering the risk of dengue shock syndrome. View Publication

Natural killer (NK) cells form an important arm of the innate immune system and function to combat a wide range of invading pathogens,ranging from viruses to bacteria. However,the means by which NK cells accomplish recognition of pathogens with a limited repertoire of receptors remain largely unknown. In the current study,we describe the recognition of an emerging fungal pathogen,Candida glabrata,by the human NK cytotoxic receptor NKp46 and its mouse ortholog,NCR1. Using NCR1 knockout mice,we observed that this receptor-mediated recognition was crucial for controlling C. glabrata infection in vitro and in vivo. Finally,we delineated the fungal ligands to be the C. glabrata adhesins Epa1,Epa6,and Epa7 and demonstrated that clearance of systemic C. glabrata infections in vivo depends on their recognition by NCR1. As NKp46 and NCR1 have been previously shown to bind viral adhesion receptors,we speculate that NKp46/NCR1 may be a novel type of pattern recognition receptor. View Publication

A variety of nonmalignant cells present in the tumor microenvironment promotes tumorigenesis by stimulating tumor cell growth and metastasis or suppressing host immunity. The role of such stromal cells in T-cell lymphoproliferative disorders is incompletely understood. Monocyte-derived cells (MDCs),including professional antigen-presenting cells such as dendritic cells (DCs),play a central role in T-cell biology. Here,we provide evidence that monocytes promote the survival of malignant T cells and demonstrate that MDCs are abundant within the tumor microenvironment of T cell-derived lymphomas. Malignant T cells were observed to remain viable during in vitro culture with autologous monocytes,but cell death was significantly increased after monocyte depletion. Furthermore,monocytes prevent the induction of cell death in T-cell lymphoma lines in response to either serum starvation or doxorubicin,and promote the engraftment of these cells in nonobese diabetic/severe combined immunodeficient mice. Monocytes are actively recruited to the tumor microenvironment by CCL5 (RANTES),where their differentiation into mature DCs is impaired by tumor-derived interleukin-10. Collectively,the data presented demonstrate a previously undescribed role for monocytes in T-cell lymphoproliferative disorders. View Publication

We have previously reported that an anti-human transferrin receptor IgG3-avidin fusion protein (anti-hTfR IgG3-Av) inhibits the proliferation of an erythroleukemia-cell line. We have now found that anti-hTfR IgG3-Av also inhibits the proliferation of additional human malignant B and plasma cells. Anti-hTfR IgG3-Av induces internalization and rapid degradation of the TfR. These events can be reproduced in cells treated with anti-hTfR IgG3 cross-linked with a secondary Ab,suggesting that they result from increased TfR cross-linking. Confocal microscopy of cells treated with anti-hTfR IgG3-Av shows that the TfR is directed to an intracellular compartment expressing the lysosomal marker LAMP-1. The degradation of TfR is partially blocked by cysteine protease inhibitors. Furthermore,cells treated with anti-hTfR IgG3-Av exhibit mitochondrial depolarization and activation of caspases 9,8,and 3. The mitochondrial damage and cell death can be prevented by iron supplementation,but cannot be fully blocked by a pan-caspase inhibitor. These results suggest that anti-hTfR IgG3-Av induces lethal iron deprivation,but the resulting cell death does not solely depend on caspase activation. This report provides insights into the mechanism of cell death induced by anti-TfR Abs such as anti-hTfR IgG3-Av,a molecule that may be useful in the treatment of B-cell malignancies such as multiple myeloma. View Publication

We analyzed 112 patients with high-risk acute myeloid leukemia (61 in complete remission [CR]; 51 in relapse),who received human leukocyte-antigen (HLA)-haploidentical transplants from natural killer (NK) alloreactive (n = 51) or non-NK alloreactive donors (n = 61). NK alloreactive donors possessed HLA class I,killer-cell immunoglobulin-like receptor (KIR) ligand(s) which were missing in the recipients,KIR gene(s) for missing self recognition on recipient targets,and alloreactive NK clones against recipient targets. Transplantation from NK-alloreactive donors was associated with a significantly lower relapse rate in patients transplanted in CR (3% versus 47%) (P textgreater .003),better event-free survival in patients transplanted in relapse (34% versus 6%,P = .04) and in remission (67% versus 18%,P = .02),and reduced risk of relapse or death (relative risk versus non-NK-alloreactive donor,0.48; 95% CI,0.29-0.78; P textgreater .001). In all patients we tested the missing ligand" model which pools KIR ligand mismatched transplants and KIR ligand-matched transplants from donors possessing KIR(s) for which neither donor nor recipient have HLA ligand(s). Only transplantation from NK-alloreactive donors is associated with a survival advantage." View Publication