技术资料

We have generated rat monoclonal antibodies specific for the mouse eotaxin receptor,C-C chemokine receptor 3 (CCR3). Several anti-CCR3 mAbs proved to be useful for in vivo depletion of CCR3-expressing cells and immunofluorescent staining. In vivo CCR3 mAbs of the IgG2b isotype substantially depleted blood eosinophil levels in Nippostrongyus brasiliensis-infected mice. Repeated anti-CCR3 mAb treatment in these mice significantly reduced tissue eosinophilia in the lung tissue and bronchoalveolar lavage fluid. Flow cytometry revealed that mCCR3 was expressed on eosinophils but not on stem cells,dendritic cells,or cells from the thymus,lymph node,or spleen of normal mice. Unlike human Th2 cells,mouse Th2 cells did not express detectable levels of CCR3 nor did they give a measurable response to eotaxin. None of the mAbs were antagonists or agonists of CCR3 calcium mobilization. To our knowledge,the antibodies described here are the first mAbs reported to be specific for mouse eosinophils and to be readily applicable for the detection,isolation,and in vivo depletion of eosinophils. View Publication

Innate immune cells adjust to microbial and inflammatory stimuli through a process termed environmental plasticity,which links a given individual stimulus to a unique activated state. Here,we report that activation of human plasmacytoid predendritic cells (pDCs) with a single microbial or cytokine stimulus triggers cell diversification into three stable subpopulations (P1-P3). P1-pDCs (PD-L1+CD80-) displayed a plasmacytoid morphology and specialization for type I interferon production. P3-pDCs (PD-L1-CD80+) adopted a dendritic morphology and adaptive immune functions. P2-pDCs (PD-L1+CD80+) displayed both innate and adaptive functions. Each subpopulation expressed a specific coding- and long-noncoding-RNA signature and was stable after secondary stimulation. P1-pDCs were detected in samples from patients with lupus or psoriasis. pDC diversification was independent of cell divisions or preexisting heterogeneity within steady-state pDCs but was controlled by a TNF autocrine and/or paracrine communication loop. Our findings reveal a novel mechanism for diversity and division of labor in innate immune cells. View Publication

BACKGROUND Atopy and viral respiratory tract infections synergistically promote asthma exacerbations. IgE cross-linking inhibits critical virus-induced IFN-α responses of plasmacytoid dendritic cells (pDCs),which can be deficient in patients with allergic asthma. OBJECTIVE We sought to determine whether reducing IgE levels in vivo with omalizumab treatment increases pDC antiviral IFN-α responses in inner-city children with asthma. METHODS PBMCs and pDCs isolated from children with exacerbation-prone asthma before and during omalizumab treatment were stimulated ex vivo with rhinovirus and influenza in the presence or absence of IgE cross-linking. IFN-α levels were measured in supernatants,and mRNA expression of IFN-α pathway genes was determined by using quantitative RT-PCR (qRT-PCR) in cell pellets. FcεRIα protein levels and mRNA expression were measured in unstimulated cells by using flow cytometry and qRT-PCR,respectively. Changes in these outcomes and associations with clinical outcomes were analyzed,and statistical modeling was used to identify risk factors for asthma exacerbations. RESULTS Omalizumab treatment increased rhinovirus- and influenza-induced PBMC and rhinovirus-induced pDC IFN-α responses in the presence of IgE cross-linking and reduced pDC surface FcεRIα expression. Omalizumab-induced reductions in pDC FcεRIα levels were significantly associated with a lower asthma exacerbation rate during the outcome period and correlated with increases in PBMC IFN-α responses. PBMC FcεRIα mRNA expression measured on study entry significantly improved an existing model of exacerbation prediction. CONCLUSIONS These findings indicate that omalizumab treatment augments pDC IFN-α responses and attenuates pDC FcεRIα protein expression and provide evidence that these effects are related. These results support a potential mechanism underlying clinical observations that allergic sensitization is associated with increased susceptibility to virus-induced asthma exacerbations. View Publication

Acute lymphoblastic leukemia (ALL) still frequently recurs after hematopoietic stem cell transplantation (HSCT),underscoring the need to improve the graft-versus-leukemia (GvL) effect. Natural killer (NK) cells reconstitute in the first months following HSCT when leukemia burden is at its lowest,but ALL cells have been shown to be resistant to NK cell-mediated killing. We show here that this resistance is overcome by NK cell stimulation with TLR-9-activated plasmacytoid dendritic cells (pDCs). NK cell priming with activated pDCs resulted in TRAIL and CD69 up-regulation on NK cells and IFN-γ production. NK cell activation was dependent on IFN-α produced by pDCs,but was not reproduced by IFN-α alone. ALL killing was further enhanced by inhibition of KIR engagement. We showed that ALL lysis was mainly mediated by TRAIL engagement,while the release of cytolytic granules was involved when ALL expressed NK cell activating receptor ligands. Finally,adoptive transfers of activated-pDCs in ALL-bearing humanized mice delayed the leukemia onset and cure 30% of mice. Our data therefore demonstrate that TLR-9 activated pDCs are a powerful tool to overcome ALL resistance to NK cell-mediated killing and to reinforce the GvL effect of HSCT. These results open new therapeutic avenues to prevent relapse in children with ALL. View Publication

Although natural Abs (NAbs) are present from birth,little is known about what drives their selection and whether they have housekeeping functions. The prototypic T15-NAb,first identified because of its protective role in infection,is representative of a special type of NAb response that specifically recognizes and forms complexes with apoptotic cells and which promotes cell-corpse engulfment by phagocytes. We now show that this T15-NAb IgM-mediated clearance process is dependent on the recruitment of C1q and mannose-binding lectin,which have known immune modulatory activities that also provide eat me" signals for enhancing phagocytosis. Further investigation revealed that the addition of T15-NAb significantly suppressed in vitro LPS-induced TNF-alpha and IL-6 secretion by the macrophage-like cell line� View Publication

The ability of NK cells to directly recognize pathogens and be activated via Toll-like receptors (TLR) is increasingly recognized. Nevertheless,controversial results on the NK cell ability to be directly activated by lipopolysaccharide (LPS),the ligand of TLR4,have been recently reported. To start elucidating the reasons explaining the contrasting observations of the literature,we focused on the potential role of currently used NK cell purification procedures to condition putative NK cell responsiveness to LPS. To do so,human NK cells were isolated by negative selection,using three different commercial kits,to be comparatively evaluated for the production of IFNgamma in response to ultra-pure LPS and/or IL-2. Despite the lack of surface TLR4,we found that two out of the three NK cell-enriched populations released IFNgamma (and one of the two,IL-12p70 as well) in response to the LPS plus IL-2 combination,whereas the last one did not. However,the two LPS plus IL-2-responsive NK cell populations were found variably contaminated with 6-sulfo LacNAc(+) dendritic cells (slanDC),demonstrated responsible for triggering,via the production of IL-12p70 in response to LPS,the release of IFNgamma by IL-2-stimulated NK cells. Accordingly,slanDC depletion completely abrogated the capacity to produce both IL-12p70 and IFNgamma in response to LPS plus IL-2 by slanDC-containing NK cells. Taken together,our data uncover that two commercially available kits,specifically designed to isolate NK cells by negative selection,also co-purify variable amounts of slanDC. The latter cells may dramatically affect the outcome of experiments carried on to evaluate NK cell responsiveness to TLR agonists such as LPS. 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

Inhibition of cytosolic DNA sensing represents a strategy that tumor cells use for immune evasion,but the underlying mechanisms are unclear. Here we have shown that CD47-signal regulatory protein α (SIRPα) axis dictates the fate of ingested DNA in DCs for immune evasion. Although macrophages were more potent in uptaking tumor DNA,increase of DNA sensing by blocking the interaction of SIRPα with CD47 preferentially occurred in dendritic cells (DCs) but not in macrophages. Mechanistically,CD47 blockade enabled the activation of NADPH oxidase NOX2 in DCs,which in turn inhibited phagosomal acidification and reduced the degradation of tumor mitochondrial DNA (mtDNA) in DCs. mtDNA was recognized by cyclic-GMP-AMP synthase (cGAS) in the DC cytosol,contributing to type I interferon (IFN) production and antitumor adaptive immunity. Thus,our findings have demonstrated how tumor cells inhibit innate sensing in DCs and suggested that the CD47-SIRPα axis is critical for DC-driven antitumor immunity. View Publication

Dendritic cells (DCs) are a heterogeneous population of professional antigen-presenting cells and are key cells of the immune system,acquiring different phenotypes in accordance with their localization during the immune response. A subset of inflammatory DCs is derived from circulating monocytes (Mo) and has a key role in inflammation and infection. The pathways controlling Mo-DC differentiation are not fully understood. Our objective was to investigate the possible role of nicotinamide adenine dinucleotide phosphate reduced form oxidases (NOXs) in Mo-DC differentiation. In this study,we revealed that Mo-DC differentiation was inhibited by NOX inhibitors and reactive oxygen species scavengers. We show that the Mo-DC differentiation was dependent on p22phox,and not on gp91phox/NOX2,as shown by the reduced Mo-DC differentiation observed in chronic granulomatous disease patients lacking p22phox. Moreover,we revealed that NOX5 expression was strongly increased during Mo-DC differentiation,but not during Mo-macrophage differentiation. NOX5 was expressed in circulating myeloid DC,and at a lower level in plasmacytoid DC. Interestingly,NOX5 was localized at the outer membrane of the mitochondria and interacted with p22phox in Mo-DC. Selective inhibitors and small interfering RNAs for NOX5 indicated that NOX5 controlled Mo-DC differentiation by regulating the JAK/STAT/MAPK and NFκB pathways. These data demonstrate that the NOX5-p22phox complex drives Mo-DC differentiation,and thus could be critical for immunity and inflammation. View Publication

Chemokine receptor CX3CR1(+) dendritic cells (DCs) have been suggested to sample intestinal antigens by extending transepithelial dendrites into the gut lumen. Other studies identified CD103(+) DCs in the mucosa,which,through their ability to synthesize retinoic acid (RA),appear to be capable of generating typical signatures of intestinal adaptive immune responses. We report that CD103 and CX3CR1 phenotypically and functionally characterize distinct subsets of lamina propria cells. In contrast to CD103(+) DC,CX3CR1(+) cells represent a nonmigratory gut-resident population with slow turnover rates and poor responses to FLT-3L and granulocyte/macrophage colony-stimulating factor. Direct visualization of cells in lymph vessels and flow cytometry of mouse intestinal lymph revealed that CD103(+) DCs,but not CX3CR1-expressing cells,migrate into the gut draining mesenteric lymph nodes (LNs) under steady-state and inflammatory conditions. Moreover,CX3CR1(+) cells displayed poor T cell stimulatory capacity in vitro and in vivo after direct injection of cells into intestinal lymphatics and appeared to be less efficient at generating RA compared with CD103(+) DC. These findings indicate that selectively CD103(+) DCs serve classical DC functions and initiate adaptive immune responses in local LNs,whereas CX3CR1(+) populations might modulate immune responses directly in the mucosa and serve as first line barrier against invading enteropathogens. View Publication