技术资料

Viral infection triggers induction of antiviral cytokines and effectors,which are critical mediators of innate antiviral immune response. It has been shown that the processing body-associated protein LSm14A is involved in the induction of antiviral cytokines in cell lines but in vivo evidence is lacking. By generating LSm14A-deficient mice,in this study,we show that LSm14A plays a critical and specific role in the induction of antiviral cytokines in dendritic cells (DCs) but not in macrophages and fibroblasts. Induction of antiviral cytokines triggered by the DNA viruses HSV-1 and murid herpesvirus 68 and the RNA virus vesicular stomatitis virus but not Sendai virus was impaired in Lsm14a(-/-) DCs,which is correlated to the functions of the adaptor protein MITA/STING in the antiviral signaling pathways. LSm14A deficiency specifically downregulated MITA/STING level in DCs by impairing its nuclear mRNA precursor processing and subsequently impaired antiviral innate and adaptive immune responses. Our findings reveal a nuclear mRNA precursor processing and cell-specific regulatory mechanism of antiviral immune responses. View Publication

IL-18 is a member of the IL-1 family involved in innate immunity and inflammation. Deregulated levels of IL-18 are involved in the pathogenesis of multiple disorders including inflammatory and metabolic diseases,yet relatively little is known regarding its regulation. Liver X receptors or LXRs are key modulators of macrophage cholesterol homeostasis and immune responses. Here we show that LXR ligands negatively regulate LPS-induced mRNA and protein expression of IL-18 in bone marrow-derived macrophages. Consistent with this being an LXR-mediated process,inhibition is abolished in the presence of a specific LXR antagonist and in LXR-deficient macrophages. Additionally,IL-18 processing of its precursor inactive form to its bioactive state is inhibited by LXR through negative regulation of both pro-caspase 1 expression and activation. Finally,LXR ligands further modulate IL-18 levels by inducing the expression of IL-18BP,a potent endogenous inhibitor of IL-18. This regulation occurs via the transcription factor IRF8,thus identifying IL-18BP as a novel LXR and IRF8 target gene. In conclusion,LXR activation inhibits IL-18 production through regulation of its transcription and maturation into an active pro-inflammatory cytokine. This novel regulation of IL-18 by LXR could be applied to modulate the severity of IL-18 driven metabolic and inflammatory disorders. View Publication

Leukocyte recruitment to inflammation sites progresses in a multistep cascade. Chemokines regulate multiple steps of the cascade,including arrest,transmigration,and chemotaxis. The most important chemokine receptor in mouse neutrophils is CXCR2,which couples through G$\alpha$i2- and G$\alpha$i3-containing heterotrimeric G proteins. Neutrophils arrest in response to CXCR2 stimulation. This is defective in G$\alpha$i2-deficient neutrophils. In this study,we show that G$\alpha$i3-deficient neutrophils showed reduced transmigration but normal arrest in mice. We also tested G$\alpha$i2- or G$\alpha$i3-deficient neutrophils in a CXCL1 gradient generated by a microfluidic device. G$\alpha$i3-,but not G$\alpha$i2-,deficient neutrophils showed significantly reduced migration and directionality. This was confirmed in a model of sterile inflammation in vivo. G$\alpha$i2-,but not G$\alpha$i3-,deficient neutrophils showed decreased Ca(2+) flux in response to CXCR2 stimulation. Conversely,G$\alpha$i3-,but not G$\alpha$i2-,deficient neutrophils exhibited reduced AKT phosphorylation upon CXCR2 stimulation. We conclude that G$\alpha$i2 controls arrest and G$\alpha$i3 controls transmigration and chemotaxis in response to chemokine stimulation of neutrophils. View Publication

Immune tolerance is executed partly by Foxp3(+)regulatory T (Treg) cells,which suppress autoreactive T cells. In autoimmune type 1 diabetes (T1D) impaired tolerance promotes destruction of insulin-producing β-cells. The development of autoantigen-specific vaccination strategies for Foxp3(+)Treg-induction and prevention of islet autoimmunity in patients is still in its infancy. Here,using human haematopoietic stem cell-engrafted NSG-HLA-DQ8 transgenic mice,we provide direct evidence for human autoantigen-specific Foxp3(+)Treg-induction in vivo. We identify HLA-DQ8-restricted insulin-specific CD4(+)T cells and demonstrate efficient human insulin-specific Foxp3(+)Treg-induction upon subimmunogenic vaccination with strong agonistic insulin mimetopes in vivo. Induced human Tregs are stable,show increased expression of Treg signature genes such as Foxp3,CTLA4,IL-2Rα and TIGIT and can efficiently suppress effector T cells. Such Foxp3(+)Treg-induction does not trigger any effector T cells. These T1D vaccine candidates could therefore represent an expedient improvement in the challenge to induce human Foxp3(+)Tregs and to develop novel precision medicines for prevention of islet autoimmunity in children at risk of T1D. View Publication

Multiple sclerosis (MS) is caused by T cells that are reactive for brain antigens. In experimental autoimmune encephalomyelitis,the animal model for MS,myelin-reactive T cells initiate the autoimmune process when entering the nervous tissue and become reactivated upon local encounter of their cognate CNS antigen. Thereby,the strength of the T-cellular reactivation process within the CNS tissue is crucial for the manifestation and the severity of the clinical disease. Recently,B cells were found to participate in the pathogenesis of CNS autoimmunity,with several diverse underlying mechanisms being under discussion. We here report that B cells play an important role in promoting the initiation process of CNS autoimmunity. Myelin-specific antibodies produced by autoreactive B cells after activation in the periphery diffused into the CNS together with the first invading pathogenic T cells. The antibodies accumulated in resident antigen-presenting phagocytes and significantly enhanced the activation of the incoming effector T cells. The ensuing strong blood-brain barrier disruption and immune cell recruitment resulted in rapid manifestation of clinical disease. Therefore,myelin oligodendrocyte glycoprotein (MOG)-specific autoantibodies can initiate disease bouts by cooperating with the autoreactive T cells in helping them to recognize their autoantigen and become efficiently reactivated within the immune-deprived nervous tissue. 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

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

Acute myeloid leukemia (AML) is the most common type of acute leukemia affecting older individuals at a median age of 67 years. Resistance to intensive induction chemotherapy is the major cause of death in elderly AML; hence novel treatment strategies are warranted. CD33-directed antibody-drug conjugates (Gemtuzumab ozogamicin) have been shown to improve overall survival,validating CD33 as a target for antibody-based therapy of AML. Here we report the in vitro efficacy of BI 836858,a fully human,Fc-engineered,anti-CD33 antibody using AML cell lines and primary AML blasts as targets. BI 836858-opsonized AML cells significantly induced both autologous and allogeneic natural killer (NK)-cell degranulation and NK cell-mediated antibody-dependent cellular cytotoxicity (ADCC). In vitro treatment of AML blasts with decitabine (DAC) or 5-azacytidine,two hypomethylating agents that show efficacy in older patients,did not compromise BI 836858-induced NK cell-mediated ADCC. Evaluation of BI 836858-mediated ADCC in serial marrow AML aspirates in patients who received a ten-day course of DAC (pre-DAC,days 4,11 and 28 post-DAC) revealed significantly higher ADCC in samples at day 28 post-DAC when compared to pre-DAC treatment. Analysis of ligands (L) to activating receptors (NKG2D showed significantly increased NKG2DL expression in day 28 post-DAC samples compared to pre-DAC samples; when NKG2DL receptor was blocked using antibodies,BI 836858-mediated ADCC was significantly decreased,suggesting that DAC enhances AML blast susceptibility to BI 836858 by upregulating NKG2DL. These data provide a rationale for combination therapy of Fc-engineered antibodies such as BI 836858 with azanucleosides in elderly patients with AML. 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