技术资料

Recent compelling evidence indicates that Th17 confer host immunity against a variety of microbes,including extracellular and intracellular pathogens. Therefore,understanding mechanisms for the induction and activation of Ag-specific Th17 is important for the rational design of vaccines against pathogens. To study this,we employed an in vitro system in which influenza hemagglutinin (HA) 1 was delivered to dendritic cells (DCs) via Dectin-1 using anti-human Dectin-1 (hDectin-1)-HA1 recombinant fusion proteins. We found that healthy individuals maintained broad ranges of HA1-specific memory Th17 that were efficiently activated by DCs targeted with anti-hDectin-1-HA1. Nonetheless,these DCs were not able to induce a significant level of HA1-specific Th17 responses even in the presence of the Th17-promoting cytokines IL-1? and IL-6. We further found that the induction of surface IL-1R1 expression by signals via TCRs and common ?-chain receptors was essential for naive CD4(+) T cell differentiation into HA1-specific Th17. This process was dependent on MyD88,but not IL-1R-associated kinase 1/4. Thus,interruptions in STAT3 or MyD88 signaling led to substantially diminished HA1-specific Th17 induction. Taken together,the de novo generation of pathogen-specific human Th17 requires complex,but complementary,actions of multiple signals. Data from this study will help us design a new and effective vaccine strategy that can promote Th17-mediated immunity against microbial pathogens. View Publication

Lymphocyte activation gene-3 (LAG-3) is an inhibitory receptor expressed by CD4+ T cells and tempers their homeostatic expansion. Because CD4+ T cell proliferation is tightly coupled to bioenergetics,we investigate the role of LAG-3 in modulating naive CD4+ T cell metabolism. LAG-3 deficiency enhances the metabolic profile of naive CD4+ T cells by elevating levels of mitochondrial biogenesis. In vivo,LAG-3 blockade partially restores expansion and the metabolic phenotype of wild-type CD4+ T cells to levels of Lag3-/- CD4+ T cells,solidifying that LAG-3 controls these processes. Lag3-/- CD4+ T cells also demonstrate greater signal transducer and activator of transcription 5 (STAT5) activation,enabling resistance to interleukin-7 (IL-7) deprivation. These results implicate this pathway as a target of LAG-3-mediated inhibition. Additionally,enhancement of STAT5 activation,as a result of LAG-3 deficiency,contributes to greater activation potential in these cells. These results identify an additional mode of regulation elicited by LAG-3 in controlling CD4+ T cell responses. View Publication

Immune activation may underlie the pathogenesis of irritable bowel syndrome (IBS),but the evidence is conflicting. We examined whether peripheral CD4+ T-cells from IBS patients demonstrated immune activation and changes in cytokine production. To gain mechanistic insight,we examined whether immune activation correlated with psychological stress and changing symptoms over time. IBS patients (n = 29) and healthy volunteers (HV; n = 29) completed symptom and psychological questionnaires. IBS patients had a significant increase in CD4+ T-cells expressing the gut homing marker integrin beta7 (p = 0.023) and lymphoid marker CD62L (p = 0.026) compared to HV. Furthermore,phytohaemagglutinin stimulated CD4+ T-cells from IBS-D patients demonstrated increased TNFalpha secretion when compared to HV (p = 0.044). Increased psychological scores in IBS did not correlate with TNFalpha production,while stress hormones inhibited cytokine secretion from CD4+ T-cells of HV in vitro. IBS symptoms,but not markers of immune activation,decreased over time. CD4+ T-cells from IBS-D patients exhibit immune activation,but this did not appear to correlate with psychological stress measurements or changing symptoms over time. This could suggest that immune activation is a surrogate of an initial trigger and/or ongoing parallel peripheral mechanisms. View Publication

CD4 T cells play a critical role in promoting the development of autoimmunity in type 1 diabetes. The diabetogenic CD4 T cell clone BDC-2.5,originally isolated from a NOD mouse,has been widely used to study the contribution of autoreactive CD4 T cells and relevant Ags to autoimmune diabetes. Recent work from our laboratory has shown that the Ag for BDC-2.5 T cells is a hybrid insulin peptide (2.5HIP) consisting of an insulin C-peptide fragment fused to a peptide from chromogranin A (ChgA) and that endogenous 2.5HIP-reactive T cells are major contributors to autoimmune pathology in NOD mice. The objective of this study was to determine if poly(lactide-co-glycolide) (PLG) nanoparticles (NPs) loaded with the 2.5HIP Ag (2.5HIP-coupled PLG NPs) can tolerize BDC-2.5 T cells. Infusion of 2.5HIP-coupled PLG NPs was found to prevent diabetes in an adoptive transfer model by impairing the ability of BDC-2.5 T cells to produce proinflammatory cytokines through induction of anergy,leading to an increase in the ratio of Foxp3+ regulatory T cells to IFN-gamma+ effector T cells. To our knowledge,this work is the first to use a hybrid insulin peptide,or any neoepitope,to re-educate diabetogenic T cells and may have significant implications for the development of an Ag-specific therapy for type 1 diabetes patients. 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

The hexamethylene bisacetamide (HMBA) anticancer drug was dismissed due to limited efficacy in leukemic patients but it may re-enter into the clinics in HIV-1 eradication strategies because of its recently disclosed capacity to reactivate latent virus. Here,we investigated the impact of HMBA on the cytotoxicity of natural killer (NK) cells against acute T lymphoblastic leukemia (T-ALL) cells or HIV-1-infected T cells that exit from latency. We show that in T-ALL cells HMBA upmodulated MICB and ULBP2 ligands for the NKG2D activating receptor. In a primary CD4+ T cell-based latency model,HMBA did not reactivate HIV-1,yet enhanced ULBP2 expression on cells harboring virus reactivated by prostratin (PRO). However,HMBA reduced the expression of NKG2D and its DAP10 adaptor in NK cells,hence impairing NKG2D-mediated cytotoxicity and DAP10-dependent response to IL-15 stimulation. Alongside,HMBA dampened killing of T-ALL targets by IL-15-activated NK cells and impaired NK cell-mediated clearance of PRO-reactivated HIV-1+ cells. Overall,our results demonstrate a dominant detrimental effect of HMBA on the NKG2D pathway that crucially controls NK cell-mediated killing of tumors and virus-infected cells,providing one possible explanation for poor clinical outcome in HMBA-treated cancer patients and raising concerns for future therapeutic application of this drug. View Publication