技术资料

We describe the generation of a fusion cytokine consisting of GM-CSF in tandem with N-terminal-truncated MCP-1 (6-76),hereafter GMME1. Treatment of activated T cells with recombinant GMME1 protein leads to proinflammatory cytokine reduction and apoptosis via a CCR2-restricted pathway. Similarly,cell death is triggered in macrophages cultured with GMME1,while an inhibition of Ab production from plasma cells is observed. Treatment of CD4 T cells derived from experimental autoimmune encephalomyelitis mice with GMME1 leads to p38 hyperphosphorylation,inhibition of p44/42,AKT and STAT3 phosphorylation,and caspase-3 activation. GMME1 administration to experimental autoimmune encephalomyelitis mice suppresses symptomatic disease and correlates with decreased levels of inflammatory cytokines including IL-17,MOG-specific Ab titers,and blockade of CD4 and CD8 T cell infiltration in spinal cords. We propose that GMME1 defines a new class of agents for the treatment of autoimmune ailments by selectively targeting lymphomyeloid cells expressing CCR2. View Publication

Canonically,immunoglobulin E (IgE) mediates allergic immune responses by triggering mast cells and basophils to release histamine and type 2 helper cytokines. Here we found that in human systemic lupus erythematosus (SLE),IgE antibodies specific for double-stranded DNA (dsDNA) activated plasmacytoid dendritic cells (pDCs),a type of cell of the immune system linked to viral defense,which led to the secretion of substantial amounts of interferon-α (IFN-α). The concentration of dsDNA-specific IgE found in patient serum correlated with disease severity and greatly potentiated pDC function by triggering phagocytosis via the high-affinity FcɛRI receptor for IgE,followed by Toll-like receptor 9 (TLR9)-mediated sensing of DNA in phagosomes. Our findings expand the known pathogenic mechanisms of IgE-mediated inflammation beyond those found in allergy and demonstrate that IgE can trigger interferon responses capable of exacerbating self-destructive autoimmune responses. View Publication

Circulating Tumor Cells (CTCs) represent an easy,repeatable and representative access to information regarding solid tumors. However,their detection remains difficult because of their paucity,their short half-life,and the lack of reliable surface biomarkers. Flow cytometry (FC) is a fast,sensitive and affordable technique,ideal for rare cells detection. Adapted to CTCs detection (i.e. extremely rare cells),most FC-based techniques require a time-consuming pre-enrichment step,followed by a 2-hours staining procedure,impeding on the efficiency of CTCs detection. We overcame these caveats and reduced the procedure to less than one hour,with minimal manipulation. First,cells were simultaneously fixed,permeabilized,then stained. Second,using low-speed FC acquisition conditions and two discriminators (cell size and pan-cytokeratin expression),we suppressed the pre-enrichment step. Applied to blood from donors with or without known malignant diseases,this protocol ensures a high recovery of the cells of interest independently of their epithelial-mesenchymal plasticity and can predict which samples are derived from cancer donors. This proof-of-concept study lays the bases of a sensitive tool to detect CTCs from a small amount of blood upstream of in-depth analyses. View Publication

PURPOSE: Immunotherapy holds promise as a new strategy for the eradication of residual cells in acute myeloid leukaemia (AML). Leukaemic antigen presenting cells (APCs) combining optimal antigen presentation and tumour antigenicity could be used as potent T cell activators. For clinical purposes it is desirable to culture APCs under serum-free conditions. Therefore,we compared morphological,immunophenotypical and functional outcome of the serum-free culture of AML-APCs to their serum-enriched culture. METHODS: AML blasts (n=19) were cultured in the presence of either a cytokine mix or calcium ionophore (CI) for 14 and 2 days,respectively,in FCS-containing medium (FCS),StemSpan serum-free medium (SP) and CellGro serum-free medium (CG). After culture relative yields were calculated and immunophenotypic analysis of APC markers was performed. The mixed leukocyte reaction (MLR) was used to determine T cell stimulating capacity. RESULTS: Serum-free culture of AML-APCs resulted in comparable morphology,relative yields and immunophenotype to serum-enriched culture. By comparing both serum-free media we observed a trend towards a more mature phenotype of CI-cultured AML-APCs in SP. MLR showed that serum-free cultured cells have equal T cell stimulatory capacity in comparison with serum-enriched culture. CONCLUSION: These data show that the serum-free culture of AML-APCs is feasible and that these APCs are comparable to serum-enriched cultured AML-APCs with regard to morphological,immunophenotypical and functional characteristics. These AML-APCs are suitable for the development of active specific immunisation protocols which meet the criteria for good clinical practise (GCP). View Publication

Emerging evidence suggests an immunosuppressive role of altered tumor glycosylation due to downregulation of innate immune responses via immunoregulatory Siglecs. In contrast,human T cells,a major anticancer effector cell,only rarely express Siglecs. However,here,we report that the majority of intratumoral,but not peripheral blood,cytotoxic CD8+ T cells expressed Siglec-9 in melanoma. We identified Siglec-9+ CD8+ T cells as a subset of effector memory cells with high functional capacity and signatures of clonal expansion. This cytotoxic T-cell subset was functionally inhibited in the presence of Siglec-9 ligands or by Siglec-9 engagement by specific antibodies. TCR signaling pathways and key effector functions (cytotoxicity,cytokine production) of CD8+ T cells were suppressed by Siglec-9 engagement,which was associated with the phosphorylation of the inhibitory protein tyrosine phosphatase SHP-1,but not SHP-2. Expression of cognate Siglec-9 ligands was observed on the majority of tumor cells in primary and metastatic melanoma specimens. Targeting the tumor-restricted,glycosylation-dependent Siglec-9 axis may unleash this intratumoral T-cell subset,while confining T-cell activation to the tumor microenvironment. View Publication

The types and magnitude of Ag-specific immune responses can be determined by the functional plasticity of dendritic cells (DCs). However,how DCs display functional plasticity and control host immune responses have not been fully understood. In this study,we report that ligation of DC-asialoglycoprotein receptor (DC-ASGPR),a C-type lectin receptor (CLR) expressed on human DCs,resulted in rapid activation of Syk,followed by PLCgamma2 and PKCdelta engagements. However,different from other Syk-coupled CLRs,including Dectin-1,signaling cascade through DC-ASGPR did not trigger NF-kappaB activation. Instead,it selectively activated MAPK ERK1/2 and JNK. Rapid and prolonged phosphorylation of ERK1/2 led to sequential activation of p90RSK and CREB,which consequently bound to IL10 promoter and initiated cytokine expression. In addition,DC-ASGPR ligation activated Akt,which differentially regulated the activities of GSK-3alpha/beta and beta-catenin and further contributed to IL-10 expression. Our observations demonstrate that DC-ASGPR induces IL-10 expression via an intrinsic signaling pathway,which provides a molecular explanation for DC-ASGPR-mediated programing of DCs to control host immune responses. View Publication

Differences in clinical outcome of simian immunodeficiency virus (SIV) infection in disease-resistant African sooty mangabeys (SM) and disease-susceptible Asian rhesus macaques (RM) prompted us to examine the role of regulatory T cells (Tregs) in these two animal models. Results from a cross-sectional study revealed maintenance of the frequency and absolute number of peripheral Tregs in chronically SIV-infected SM while a significant loss occurred in chronically SIV-infected RM compared to uninfected animals. A longitudinal study of experimentally SIV-infected animals revealed a transient increase in the frequency of Tregs from baseline values following acute infection in RM,but no change in the frequency of Tregs occurred in SM during this period. Further examination revealed a strong correlation between plasma viral load (VL) and the level of Tregs in SIV-infected RM but not SM. A correlation was also noted in SIV-infected RM that control VL spontaneously or in response to antiretroviral chemotherapy. In addition,immunofluorescent cell count assays showed that while Treg-depleted peripheral blood mononuclear cells from RM led to a significant enhancement of CD4+ and CD8+ T-cell responses to select pools of SIV peptides,there was no detectable T-cell response to the same pool of SIV peptides in Treg-depleted cells from SIV-infected SM. Our data collectively suggest that while Tregs do appear to play a role in the control of viremia and the magnitude of the SIV-specific immune response in RM,their role in disease resistance in SM remains unclear. View Publication

Small intestinal CD103(+) dendritic cells (DCs) have the selective ability to promote de novo generation of regulatory T cells via the production of retinoic acid (RA). Considering that aldehyde dehydrogenase (ALDH) activity controls the production of RA,we used a flow cytometry-based assay to measure ALDH activity at the single-cell level and to perform a comprehensive analysis of the RA-producing DC populations present in lymphoid and nonlymphoid mouse tissues. RA-producing DCs were primarily of the tissue-derived,migratory DC subtype and can be readily found in the skin and in the lungs as well as in their corresponding draining lymph nodes. The RA-producing skin-derived DCs were capable of triggering the generation of regulatory T cells,a finding demonstrating that the presence of RA-producing,tolerogenic DCs is not restricted to the intestinal tract as previously thought. Unexpectedly,the production of RA by skin DCs was restricted to CD103(-) DCs,indicating that CD103 expression does not constitute a universal" marker for RA-producing mouse DCs. Finally� View Publication

Frequent hallmarks of T-cell acute lymphoblastic leukemia (T-ALL) include aberrant NOTCH signaling and deletion of the CDKN2A locus,which contains 2 closely linked tumor suppressor genes (INK4A and ARF). When bone marrow cells or thymocytes transduced with a vector encoding the constitutively activated intracellular domain of Notch1 (ICN1) are expanded ex vivo under conditions that support T-cell development,cultured progenitors rapidly induce CD4+/CD8+ T-ALLs after infusion into healthy syngeneic mice. Under these conditions,enforced ICN1 expression also drives formation of T-ALLs in unconditioned CD-1 nude mice,bypassing any requirements for thymic maturation. Retention of Arf had relatively modest activity in suppressing the formation of T-ALLs arising from bone marrow-derived ICN1+ progenitors in which the locus is epigenetically silenced,and all resulting Arf (+/+) tumors failed to express the p19(Arf) protein. In striking contrast,retention of Arf in thymocyte-derived ICN1+ donor cells significantly delayed disease onset and suppressed the penetrance of T-ALL. Use of cultured thymocyte-derived donor cells expressing a functionally null Arf-GFP knock-in allele confirmed that ICN1 signaling can induce Arf expression in vivo. Arf activation by ICN1 in T cells thereby provides stage-specific tumor suppression but also a strong selective pressure for deletion of the locus in T-ALL. View Publication