技术资料

Invariant natural killer T (iNKT) cells are a unique lymphocyte subpopulation that mediates antitumor activities upon activation. A current strategy to harness iNKT cells for cancer treatment is endogenous iNKT cell activation using patient-derived dendritic cells (DCs). However,the limited number and functional defects of patient DCs are still the major challenges for this therapeutic approach. In this study,we investigated whether human embryonic stem cells (hESCs) with an ectopically expressed CD1d gene could be exploited to address this issue. Using a lentivector carrying an optimized expression cassette,we generated stably modified hESC lines that consistently overexpressed CD1d. These modified hESC lines were able to differentiate into DCs as efficiently as the parental line. Most importantly,more than 50% of such derived DCs were CD1d+. These CD1d-overexpressing DCs were more efficient in inducing iNKT cell response than those without modification,and their ability was comparable to that of DCs generated from monocytes of healthy donors. The iNKT cells expanded by the CD1d-overexpressing DCs were functional,as demonstrated by their ability to lyse iNKT cell-sensitive glioma cells. Therefore,hESCs stably modified with the CD1d gene may serve as a convenient,unlimited,and competent DC source for iNKT cell-based cancer immunotherapy. View Publication

The recruitment of monocytes and their differentiation into macrophages at sites of inflammation are key events in determining the outcome of the inflammatory response and initiating the return to tissue homeostasis. To study monocyte trafficking and macrophage differentiation in vivo,we have generated a novel transgenic reporter mouse expressing a green fluorescent protein (GFP) under the control of the human CD68 promoter. CD68-GFP mice express high levels of GFP in both monocyte and embryo-derived tissue resident macrophages in adult animals. The human CD68 promoter drives GFP expression in all CD115(+) monocytes of adult blood,spleen,and bone marrow; we took advantage of this to directly compare the trafficking of bone marrow-derived CD68-GFP monocytes to that of CX3CR1(GFP) monocytes in vivo using a sterile zymosan peritonitis model. Unlike CX3CR1(GFP) monocytes,which downregulate GFP expression on differentiation into macrophages in this model,CD68-GFP monocytes retain high-level GFP expression for 72 hours after differentiation into macrophages,allowing continued cell tracking during resolution of inflammation. In summary,this novel CD68-GFP transgenic reporter mouse line represents a powerful resource for analyzing monocyte mobilization and monocyte trafficking as well as studying the fate of recruited monocytes in models of acute and chronic inflammation. View Publication

BACKGROUND: Conventional regulatory T cells (Tregs) can suppress human immunodeficiency virus type 1 (HIV-1)-specific immune responses but cannot control immune activation in primary HIV infection. Here,we characterized Treg subsets,using recently defined phenotypic delineation,and analyzed the relative contribution of cell subsets to the production of immunosuppressive cytokines in primary HIV infection. METHODS: In a longitudinal prospective study,ex vivo phenotyping of fresh peripheral blood mononuclear cells from patients with primary HIV infection was performed at baseline and month 6 of follow-up to characterize Treg subsets,immune activation,and cytokine production in isolated CD4(+) T cells. RESULTS: The frequency of CD4(+)CD25(+)CD127(low) Tregs and the distribution between the naive,memory,and activated/memory Treg subsets was similar in patients and healthy donors. However,Tregs from patients with primary HIV infection showed peculiar phenotypic profiles,such as elevated FoxP3,ICOS,and CTLA-4 expression,with CTLA-4 expression strikingly increased in all Treg subsets both at baseline and month 6 of follow-up. The great majority of interleukin 10 (IL-10)-producing CD4(+) T cells were FoxP3(neg) (ie,Tr1-like cells). In contrast to conventional Tregs,Tr1-like cells were inversely correlated with immune activation and not associated with lower effector T-cell responses. CONCLUSION: FoxP3(neg) Tr1-like cells-major contributors to IL-10 production-may have a beneficial role by controlling immune activation in early HIV infection. View Publication

The localization of memory T cells to human skin is essential for long-term immune surveillance and the maintenance of barrier integrity. The expression of CCR8 during naive T cell activation is controlled by skin-specific factors derived from epidermal keratinocytes and not by resident dendritic cells. In this study,we show that the CCR8-inducing factors are heat stable and protease resistant and include the vitamin D3 metabolite 1α,25-dihydroxyvitamin D3 and PGE2. The effect of either metabolite alone on CCR8 expression was weak,whereas their combination resulted in robust CCR8 expression. Elevation of intracellular cAMP was essential because PGE2 could be substituted with the adenylyl cyclase agonist forskolin,and CCR8 expression was sensitive to protein kinase A inhibition. For effective induction,exposure of naive T cells to these epidermal factors needed to occur either prior to or during T cell activation even though CCR8 was only detected 4-5 d later in proliferating T cells. The importance of tissue environments in maintaining cellular immune surveillance networks within distinct healthy tissues provides a paradigm shift in adaptive immunity. Epidermal-derived vitamin D3 metabolites and PGs provide an essential cue for the localization of CCR8(+) immune surveillance T cells within healthy human skin. View Publication

Downregulation of host gene expression is one of the many strategies employed by intracellular pathogens such as Mycobacterium tuberculosis (MTB) to survive inside the macrophages and cause disease. The underlying molecular mechanism behind the downregulation of host defense gene expression is largely unknown. In this study we explored the role of histone deacetylation in macrophages in response to infection by virulent MTB H37Rv in manipulating host gene expression. We show a significant increase in the levels of HDAC1 with a concomitant and marked reduction in the levels of histone H3-acetylation in macrophages containing live,but not killed,virulent MTB. Additionally,we show that HDAC1 is recruited to the promoter of IL-12B in macrophages infected with live,virulent MTB,and the subsequent hypoacetylation of histone H3 suppresses the expression of this gene which plays a key role in initiating Th1 responses. By inhibiting immunologically relevant kinases,and by knockdown of crucial transcriptional regulators,we demonstrate that protein kinase-A (PKA),CREB,and c-Jun play an important role in regulating HDAC1 level in live MTB-infected macrophages. By chromatin immunoprecipitation (ChIP) analysis,we prove that HDAC1 expression is positively regulated by the recruitment of c-Jun to its promoter. Knockdown of HDAC1 in macrophages significantly reduced the survival of intracellular MTB. These observations indicate a novel HDAC1-mediated epigenetic modification induced by live,virulent MTB to subvert the immune system to survive and replicate in the host. View Publication

The p110δ isoform of PI3K is known to play an important role in immunity,yet its contribution to CTL responses has not been fully elucidated. Using murine p110δ-deficient CD8(+) T cells,we demonstrated a critical role for the p110δ subunit in the generation of optimal primary and memory CD8(+) T cell responses. This was demonstrated in both acute viral and intracellular bacterial infections in mice. We show that p110δ signaling is required for CD8(+) T cell activation,proliferation and effector cytokine production. We provide evidence that the effects of p110δ signaling are mediated via Akt activation and through the regulation of TCR-activated oxidative phosphorylation and aerobic glycolysis. In light of recent clinical trials that employ drugs targeting p110δ in certain cancers and other diseases,our study suggests caution in using these drugs in patients,as they could potentially increase susceptibility to infectious diseases. These studies therefore reveal a novel and direct role for p110δ signaling in in vivo CD8(+) T cell immunity to microbial pathogens. View Publication

A novel subset of human regulatory B-cells has recently been described. They arise from within the transitional B-cell subpopulation and are characterised by the production of IL-10. They appear to be of significant importance in regulating T-cell immunity in vivo. Despite this important function,the molecular mechanisms by which they control T-cell activation are incompletely defined. Here we show that transitional B-cells produced more IL-10 and expressed higher levels of IL-10 receptor after CD40 engagement compared to other B-cell subsets. Furthermore,under this stimulatory condition,CD86 expressed by transitional B-cells was down regulated and T-cell proliferation was reduced. We provide evidence to demonstrate that the down-regulation of CD86 expression by transitional B-cells was due to the autocrine effect of IL-10,which in turn leads to decreased T-cell proliferation and TNF-α production. This analysis was further extended to peripheral B-cells in kidney transplant recipients. We observed that B-cells from patients tolerant to the graft maintained higher IL-10 production after CD40 ligation,which correlates with lower CD86 expression compared to patients with chronic rejection. Hence,the results obtained in this study shed light on a new alternative mechanism by which transitional B-cells inhibit T-cell proliferation and cytokine production. View Publication

Hypoxia-inducible transcription factors (HIFs) regulate a wide array of adaptive responses to hypoxia and are often activated in solid tumors and hematologic malignancies due to intratumoral hypoxia and emerging new layers of regulation. We found that in chronic lymphocytic leukemia (CLL),HIF-1α is a novel regulator of the interaction of CLL cells with protective leukemia microenvironments and,in turn,is regulated by this interaction in a positive feedback loop that promotes leukemia survival and propagation. Through unbiased microarray analysis,we found that in CLL cells,HIF-1α regulates the expression of important chemokine receptors and cell adhesion molecules that control the interaction of leukemic cells with bone marrow and spleen microenvironments. Inactivation of HIF-1α impairs chemotaxis and cell adhesion to stroma,reduces bone marrow and spleen colonization in xenograft and allograft CLL mouse models,and prolongs survival in mice. Of interest,we found that in CLL cells,HIF-1α is transcriptionally regulated after coculture with stromal cells. Furthermore,HIF-1α messenger RNA levels vary significantly within CLL patients and correlate with the expression of HIF-1α target genes,including CXCR4,thus further emphasizing the relevance of HIF-1α expression to CLL pathogenesis. View Publication

The youngest peripheral T cells (recent thymic emigrants [RTEs]) are functionally distinct from naive T cells that have completed postthymic maturation. We assessed the RTE memory response and found that RTEs produced less granzyme B than their mature counterparts during infection but proliferated more and,therefore,generated equivalent target killing in vivo. Postinfection,RTE numbers contracted less dramatically than those of mature T cells,but RTEs were delayed in their transition to central memory,displaying impaired expression of CD62L,IL-2,Eomesodermin,and CXCR4,which resulted in impaired bone marrow localization. RTE-derived and mature memory cells expanded equivalently during rechallenge,indicating that the robust proliferative capacity of RTEs was maintained independently of central memory phenotype. Thus,the diminished effector function and delayed central memory differentiation of RTE-derived memory cells are counterbalanced by their increased proliferative capacity,driving the efficacy of the RTE response to that of mature T cells. View Publication

Recent advances in immunometabolism link metabolic changes in stimulated macrophages to production of IL-1β,a crucial cytokine in the innate immune response to Mycobacterium tuberculosis. To investigate this pathway in the host response to M. tuberculosis,we performed metabolic and functional studies on human alveolar macrophages,human monocyte-derived macrophages,and murine bone marrow-derived macrophages following infection with the bacillus in vitro. M. tuberculosis infection induced a shift from oxidative phosphorylation to aerobic glycolysis in macrophages. Inhibition of this shift resulted in decreased levels of proinflammatory IL-1β and decreased transcription of PTGS2,increased levels of anti-inflammatory IL-10,and increased intracellular bacillary survival. Blockade or absence of IL-1R negated the impact of aerobic glycolysis on intracellular bacillary survival,demonstrating that infection-induced glycolysis limits M. tuberculosis survival in macrophages through induction of IL-1β. Drugs that manipulate host metabolism may be exploited as adjuvants for future therapeutic and vaccination strategies. View Publication

Developing vaccine strategies to generate high numbers of Ag-specific CD8 T cells may be necessary for protection against recalcitrant pathogens. Heterologous prime-boost-boost immunization has been shown to result in large quantities of functional memory CD8 T cells with protective capacities and long-term stability. Completing the serial immunization steps for heterologous prime-boost-boost can be lengthy,leaving the host vulnerable for an extensive period of time during the vaccination process. We show in this study that shortening the intervals between boosting events to 2 wk results in high numbers of functional and protective Ag-specific CD8 T cells. This protection is comparable to that achieved with long-term boosting intervals. Short-boosted Ag-specific CD8 T cells display a canonical memory T cell signature associated with long-lived memory and have identical proliferative potential to long-boosted T cells Both populations robustly respond to antigenic re-exposure. Despite this,short-boosted Ag-specific CD8 T cells continue to contract gradually over time,which correlates to metabolic differences between short- and long-boosted CD8 T cells at early memory time points. Our studies indicate that shortening the interval between boosts can yield abundant,functional Ag-specific CD8 T cells that are poised for immediate protection; however,this is at the expense of forming stable long-term memory. View Publication

Human melanoma cells express various tumour antigens that are recognized by CD8(+) cytotoxic T lymphocytes (CTLs) and elicit tumour-specific responses in vivo. However,natural and therapeutically enhanced CTL responses in melanoma patients are of limited efficacy. The mechanisms underlying CTL effector phase failure when facing melanomas are still largely elusive. Here we show that,on conjugation with CTL,human melanoma cells undergo an active late endosome/lysosome trafficking,which is intensified at the lytic synapse and is paralleled by cathepsin-mediated perforin degradation and deficient granzyme B penetration. Abortion of SNAP-23-dependent lysosomal trafficking,pH perturbation or impairment of lysosomal proteolytic activity restores susceptibility to CTL attack. Inside the arsenal of melanoma cell strategies to escape immune surveillance,we identify a self-defence mechanism based on exacerbated lysosome secretion and perforin degradation at the lytic synapse. Interfering with this synaptic self-defence mechanism might be useful in potentiating CTL-mediated therapies in melanoma patients. View Publication