HIV-1 Nef protein expression in human CD34+ progenitors impairs the differentiation of an early T/NK cell precursor

HIV-1 impairs the production of T cells, through mechanisms that are still unknown. Here, we investigated the effect of the expression of HIV-1 Nef on the T-cell potential of human hematopoietic CD34(+) precursors. Those progenitors were transduced by using lentiviral vectors expressing Nef and cultured on OP9-DL1 cells allowing the differentiation of T cell from human hematopoietic precursors. We demonstrate that Nef impairs the generation of a CD3epsilon(+)CD5(+) CD1a(+) precursor stage that has initiated a D-J rearrangement of the TCRbeta locus. Onward stages of T-cell development were also affected with a quantitative reduction of CD4(+) intraCD3epsilon(+) Immature single positive cells (ISP), Double Positive (DP) CD4(+)CD8(+) TCRalphabeta T cells and CD56(+) NK cells. But B cell production was not affected. Limiting dilution analyses demonstrated a significant reduction in the frequency of T/NK progenitors among Nef-expressing CD34(+) cells. Altogether, these data demonstrate that Nef interferes with the differentiation of a primitive lymphoid human precursor with a T/NK potential.     

A human CD34(+) subset resides in lymph nodes and differentiates into CD56bright natural killer cells

In humans, T cells differentiate in thymus and B cells develop in bone marrow (BM), but the natural killer (NK) precursor cell(s) and site(s) of NK development are unclear. The CD56bright NK subset predominates in lymph nodes (LN) and produces abundant cytokines compared to the cytolytic CD56dim NK cell that predominates in blood. Here, we identify a novel CD34dimCD45RA(+) hematopoietic precursor cell (HPC) that is integrin alpha4beta7bright. CD34dimCD45RA(+)beta7bright HPCs constitute <1% of BM CD34(+) HPCs and approximately 6% of blood CD34(+) HPCs, but >95% of LN CD34(+) HPCs. They reside in the parafollicular T cell regions of LN with CD56bright NK cells, and when stimulated by IL-15, IL-2, or activated LN T cells, they become CD56bright NK cells. The data identify a new NK precursor and support a model of human NK development in which BM-derived CD34dimCD45RA(+)beta7bright HPCs reside in LN where endogenous cytokines drive their differentiation to CD56bright NK cells in vivo.     

Importance of stromal determinants in the generation of dendritic and natural killer cells in the human spleen

Summary The interaction between stroma and blood cells in the human spleen has received little attention, despite their well-defined roles during blood cell development in bone marrow. We have reported previously that human spleen-derived fibroblasts display a differentiated myofibroblast phenotype and constitutively express a biologically active form of membrane interleukin (IL)-15 that can drive co-cultured CD34(+) blood cells to differentiate into activated natural killer (NK) cells. Here, we show that, in addition to NK cells, CD34/fibroblast co-cultures also yield myeloid CD1a(+)CD38(+)CD68(+)CD86(+) HLA-DR(+)CD14(-)CD80(-) dendritic cells (DCs) after 3-4 weeks in culture. We found that DC development depended on endogenously secreted stromal macrophage colony-stimulating factor (M-CSF) and CD40/CD40L interaction rather than on fibroblast- and CD34-derived membrane IL-15. CD1a(+) cells were necessary for co-produced NK cells to acquire lytic functions by a mechanism involving cell-to-cell contact and DC-derived IL-12. This study highlights the importance of spleen myofibroblasts in the in vitro generation of two distinct cell types (DC and NK cells) from the innate immune system and suggests that the human spleen is involved in the generation of NK cells from circulating progenitors.     

Effects of Delta1 and Jagged1 on early human hematopoiesis: correlation with expression of notch signaling-related genes in CD34+ cells

It has been shown that Notch signaling mediated by ligands of both Jagged and Delta families expands the hematopoietic stem cell compartment while blocking or delaying terminal myeloid differentiation. Here we show that Delta1- and Jagged1-expressing stromal cells have distinct effects on the clonogenic and differentiation capacities of human CD34(+) CD38(+) cells. Jagged1 increases the number of bipotent colony-forming unit-granulocyte macrophage (CFU-GM) and unipotent progenitors (CFU-granulocytes and CFU-macrophages), without quantitatively affecting terminal cell differentiation, whereas Delta1 reduces the number of CFU-GM and differentiated monocytic cells. Expression analysis of genes coding for Notch receptors, Notch targets, and Notch signaling modulators in supernatant CD34(+) cells arising upon contact with Jagged1 and Delta1 shows dynamic and differential gene expression profiles over time. At early time points, modest upregulation of Notch1, Notch3, and Hes1 was observed in Jagged1-CD34(+) cells, whereas those in contact with Delta1 strikingly upregulated Notch3 and Hes1. Later, myeloid progenitors with strong clonogenic potential emerging upon contact with Jagged1 upregulated Notch1 and Deltex and downregulated Notch signaling modulators, whereas T/NK progenitors originated by Delta1 strikingly upregulated Notch3 and Deltex and, to a lesser extent, Hes1, Lunatic Fringe, and Numb. Together, the data unravel previously unrecognized expression patterns of Notch signaling-related genes in CD34(+) CD38(+) cells as they develop in Jagged1- or Delta1-stromal cell environments, which appear to reflect sequential maturational stages of CD34(+) cells into distinct cell lineages.     

Transient Notch signaling induces NK cell potential in Pax5-deficient pro-B cells

Unlike early B/T cell development, NK cell lineage commitment is not well understood, with a major limitation being the lack of a robust culture system to assay NK cell progenitors. Here we have exploited the multi-lineage potential of Pax5(-/-) pro-B cells to establish an effective system to direct differentiation of progenitors into the NK cell lineage. Cultivation of Pax5(-/-) pro-B cells on OP9 cells expressing the Notch ligand Delta-Like1 (OP9-DL1) in the presence of IL-7 efficiently induced T and NK cell potential. For NK cells, Notch was only transiently required, as prolonged signaling decreased NK and increased T cell development. Pure NK cell populations could be obtained by the culture of these Notch signal-experienced cells onto OP9 stroma and IL-15. A similar transient exposure to Notch was also compatible with the differentiation of NK cells from hematopoietic progenitors, while sustained Notch signaling impaired NK cell generation. Pax5(-/-) pro-B cell-derived NK cells were cytotoxic, secreted cytokines and expressed all the expected NK cell-specific surface markers examined except the Ly49 family, a phenotype similar to fetal NK cells. These data indicate that Notch signaling induces T/NK cell differentiation in Pax5(-/-) pro-B cells that is strikingly similar to early thymopoiesis.     

Interleukin-15 Promotes the Commitment of Cord Blood CD34^＋ Stem Cells into NK Cells

Naturalkiller(NK)cellsweresubgroupoflymphocytes thatplayedanessentialroleinthecellularbasedimmune defenseagainstvirus infectedandtransfectedcells.His torically,inteleukin 2(IL 2)wasregardedasthenatural activatorforNKcells.Recently,itwasdiscoveredthat IL …     

Delta-1对IL-6R+髓系祖细胞分化的影响

目的 探讨Notch配体Delta-1在髓系造血细胞分化过程中对膜结合和可溶性IL-6受体所介导信号的调节作用.方法 分离正常脐血单核细胞,然后利用CD34免疫磁珠试剂盒和FACSVantage流式细胞仪从所获单核细胞中拣选CD34 CD38-细胞;将CD34 CD38-细胞利用SCF、Flt3L、TPO和IL-3(4GFs)培养7 d,用CD36免疫磁珠试剂盒分离掉培养细胞中的CD36 红系祖细胞,然后用FACSVantage流式细胞仪将细胞再次拣选出CDl15- CD14- CD1a- IL-6R 表型的细胞,将这种表型的细胞用含有4GFs、4GFs IL-6或4GFs FP6培养基在有或无Delta-1存在的条件下进行培养11 d,并对CD15 粒细胞、CD14 单核细胞和CD14-CD1a 树突状细胞进行计数.结果 发现所有CD15、CD14或CD1a阳性的细胞均表达IL-6R;IL-6和FP6可促进CD15 细胞的分化;Delta-1在无IL-6和FP6存在时对CD15 细胞的分化表现出轻度的抑制作用;在IL-6和FP6存在时对CD15 粒细胞的分化表现出明显的抑制作用;相反,IL-6和FP6抑制CD14-CD1a 细胞的分化,而Delta-1促进CDl4-CD1a 细胞的分化.结论 Delta-1可通过抑制mIL-6R-和sIL-6R所介导的IL-6生物学效应抑制IL-6R 髓系祖细胞分化为粒细胞和单核细胞,但促进其分化为树突状细胞.     

CCR1 chemokine receptor expression isolates erythroid from granulocyte-macrophage progenitors

Simple methods that separate progenitor cells of different hemopoietic lineages would facilitate studies on lineage commitment and differentiation. We used an antibody specific for the chemokine receptor CCR1 to examine mononuclear cells isolated from cord blood samples. When CD34(+) cells were separated into CD34(+)CCR1(+) and CD34(+)CCR1(-) cells and plated in colony-forming assays, the granulocyte/macrophage progenitors were found almost exclusively in the CD34(+)CCR1(+) cells. In contrast, the CD34(+)CCR1(-) cells contained the majority of the erythroid progenitors. There was a highly significant difference (P<0.002) in the total percentage distribution of both granulocyte-macrophage colony-forming cells and erythroid burst-forming units between the two populations. This is the first report of separation of erythroid progenitors from granulocyte/macrophage progenitors using a chemokine receptor antibody in cord blood samples. These results suggest that at the clonogenic progenitor cell stage the expression of CCR1 might be lineage-specific. This method should prove useful for studies on erythroid progenitor and granulocyte/macrophage differentiation.     

CD4+CD25+Foxp3+IFN-γ+ human induced T regulatory cells are induced by interferon-γ and suppress alloresponses nonspecifically

Interferon-γ (IFN-γ)-producing CD3(+)CD4(+)CD25(+)Foxp3(+) peripheral blood lymphocytes (PBL) are more frequently detectable in patients with good than in patients with impaired long-term kidney graft function, suggesting an immunoregulatory role of this induced T regulatory (iTreg) subtype. Herein, the in vitro function of separated CD3(+)CD4(+)CD25(+)Foxp3(+)IFN-γ(+) PBL that were induced by phorbol 12-myristate 13-acetate (PMA)/ionomycin or alloantigenic stimulation was investigated using cell coculture techniques and flow cytometry. CD4(+)CD25(+)Foxp3(+) PBL with intracellular IFN-γ production increased to 26% in cell cultures stimulated with PMA/ionomycin for 6 hours. Recombinant IFN-γ augmented and anti-IFN-γ monoclonal antibody blocked induction of CD4(+)CD25(+)Foxp3(+)IFN-γ(+) PBL, suggesting their IFN-γ-dependent induction. In addition, CD4(+)CD25(+)Foxp3(+)IFN-γ(+) PBL produced immunosuppressive interleukin (IL)-10, transforming growth factor-β, and IL-4 intracellularly and expressed both IFN-γ and IFN-γ receptors (CD119) on the cell surface, allowing separation of CD4(+)CD25(+)IFN-γ(+) PBL with 98% purity. Addition of enriched CD4(+)CD25(+)IFN-γ(+) PBL to autologous PMA/ionomycin stimulated PBL decreased blast formation (p < 0.05), indicating suppression of cell proliferation by CD4(+)CD25(+)IFN-γ(+) PBL. CD4(+)CD25(+)IFN-γ(+) PBL separated from primary mixed leukocyte cultures (MLC) and added to autologous or third-party secondary MLC suppressed allogeneic T-cell activation nonspecifically (p < 0.05). We conclude that CD4(+)CD25(+)Foxp3(+)IFN-γ(+) PBL are induced by IFN-γ, making them sensors for IFN-γ and initial immune responses. Circulating CD4(+)CD25(+)Foxp3(+)IFN-γ(+) PBL could suppress allogeneic T-cell responses in patients and may be involved in inhibition of the posttransplant alloresponse.     

重组人IL-15促人脐血CD34+造血干细胞定向分化为NK细胞

目的 探讨IL－15促CD34^ 造血干细胞定向分化为NK细胞的作用。方法 采用MACS法分离脐血中CD34^ 细胞，分别用IL－15、SCF（造血干细胞因子）和IL－15 SCF体外培养，流式细胞仪测定CD3、CD16、CD56分子，MTT法检测NK细胞杀伤活性。结果 IL－15可以促进CD34^ 细胞分化为以CD56^ CD16^-为主的NK细胞，SCF具有较强的协同作用。结论 IL－15具有促使NK细胞定向分化的作用。     

Inhibition of LTi Cell Development by CD25 Blockade Is Associated with Decreased Intrathecal Inflammation in Multiple Sclerosis

Genetic polymorphisms in the interleukin-2 receptor α (IL-2Rα) chain (CD25) locus are associated with several human autoimmune diseases, including multiple sclerosis (MS). Blockade of CD25 by the humanized monoclonal antibody daclizumab decreases MS-associated inflammation but has surprisingly limited direct inhibitory effects on activated T cells. The present study describes unexpected effects of daclizumab therapy on innate lymphoid cells (ILCs). The number of circulating retinoic acid receptor-related orphan receptor γt-positive ILCs, which include lymphoid tissue inducer (LTi) cells, was found to be elevated in untreated MS patients compared to healthy subjects. Daclizumab therapy not only decreased numbers of ILCs but also modified their phenotype away from LTi cells and toward a natural killer (NK) cell lineage. Mechanistic studies indicated that daclizumab inhibited differentiation of LTi cells from CD34(+) hematopoietic progenitor cells or c-kit(+) ILCs indirectly, steering their differentiation toward immunoregulatory CD56(bright) NK cells through enhanced intermediate-affinity IL-2 signaling. Because adult LTi cells may retain lymphoid tissue-inducing capacity or stimulate adaptive immune responses, we indirectly measured intrathecal inflammation in daclizumab-treated MS patients by quantifying the cerebrospinal fluid chemokine (C-X-C motif) ligand 13 and immunoglobulin G index. Both of these inflammatory biomarkers were inhibited by daclizumab treatment. Our study indicates that ILCs are involved in the regulation of adaptive immune responses, and their role in human autoimmunity should be investigated further, including their potential as therapeutic targets.     

Anti-IL-5 (mepolizumab) therapy induces bone marrow eosinophil maturational arrest and decreases eosinophil progenitors in the bronchial mucosa of atopic asthmatics

BACKGROUND: Eosinophils develop from CD34(+) progenitors under the influence of IL-5. Atopic asthmatic individuals have increased numbers of mature eosinophils and eosinophil pro-genitors within their bone marrow and bronchial mucosa. We have previously reported that anti-IL-5 monoclonal antibody treatment decreases total bone marrow and bronchial mucosal eosinophil numbers in asthma. OBJECTIVE: Using an anti-IL-5 monoclonal antibody, we examined the role of IL-5 in eosinophil development within the bone marrow and bronchial mucosa in asthma. METHODS: Blood, bone marrow, and airway mucosal biopsy specimens were examined before and after anti-IL-5 (mepolizumab) treatment of asthmatic individuals in a double-blind, placebo-controlled trial. Numbers of mature and immature eosinophils were measured by histologic stain (bone marrow myelocytes, metamyelocytes, and mature eosinophils), flow cytometry (bone marrow and blood CD34(+)/IL-5Ralpha(+) cells), enumeration of bone marrow-derived eosinophil/basophil colony-forming units in methylcellulose culture, and sequential immunohistochemistry and in situ hybridization (bronchial mucosal CD34(+)/IL-5Ralpha mRNA(+) cells). RESULTS: Mepolizumab decreased mature eosinophil numbers in the bone marrow by 70% (P =.017) in comparison with placebo and decreased numbers of eosinophil myelocytes and metamyelocytes by 37% (P =.006) and 44% (P =.003), respectively. However, mepolizumab had no effect on numbers of blood or bone marrow CD34(+), CD34(+)/IL-5Ralpha(+) cells, or eosinophil/basophil colony-forming units. There was a significant decrease in bronchial mucosal CD34(+)/IL-5Ralpha mRNA(+) cell numbers in the anti-IL-5 treated group (P =.04). CONCLUSION: These data suggest that anti-IL-5 therapy might induce partial maturational arrest of the eosinophil lineage in the bone marrow. The reduction in airway CD34(+)/IL-5 mRNA(+) cell numbers suggests that IL-5 might also be required for local tissue eosinophilopoiesis.     

Natural killer cell mediated cytotoxicity of tumor cells initiated by neem leaf preparation is associated with CD40-CD40L-mediated endogenous production of interleukin-12

Neem leaf preparation (NLP) was found to activate natural killer (NK) cells (CD56(+)CD3(-)) to enhance their cytotoxic ability to tumor cells and stimulate the release of interleukin-12 (IL-12) from macrophages from healthy individuals and head-and-neck squamous cell carcinoma patients. NLP upregulated cytotoxic (CD16(+) and CD56(dim)) NK cells, and the cytotoxicity of NK-sensitive K562 cells by NLP-stimulated peripheral blood mononuclear cells decreased significantly after IL-12 neutralization. This NK-mediated cytotoxicity was manifest by upregulation of IL-12-dependent intracellular expression of the perforin-granzyme B system. Moreover, NK cytotoxic function was abolished after use of concanamycin A, a perforin inhibitor, but not by brefeldin A, a Fas inhibitor, confirming the participation of the perforin-granzyme B system. In addition NLP upregulated the expression of CD40 in CD14(+) monocytes and CD40L in CD56(+) lymphocytes. Neutralization of CD40 and CD40L in NLP-stimulated peripheral blood mononuclear cells culture resulted in significant downregulation of IL-12 release and cytotoxicity of NK cells, demonstrating the role of a CD40-CD40L interaction in the observed functions. Signals involved in the NLP-induced release of IL-12, and thereby induction of NK cell cytotoxicity, are mediated by activating p38MAPK pathway, but not through the ERK1/2 signaling pathway. Overall the results suggest that NLP effects NK cellular cytotoxicity by CD40-CD40L-mediated endogenous production of IL-12, which critically controls perforin-dependent tumor cell cytotoxicity.     

Bcl-xL is associated with the anti-apoptotic effect of IL-15 on the survival of CD56(dim) natural killer cells

Human NK cells can be distinguished into CD56(bright) and CD56(dim) subsets based on cell surface CD56 density. It has been shown that IL-2 and IL-15 have opposing effects on life and death of CD8(+) T cells. However, the roles of IL-2 and IL-15 in regulating these two NK cell subsets remain elusive. In this study, we comparatively analyzed the effects of IL-2 and IL-15 on two NK cell subsets. IL-15 improved the proliferation and activation of CD56(dim) NK cells in long-term cord blood mononuclear cell culture, but IL-2 only maintained the survival of CD56(bright) NK cells. The percentage of CD56(+)Annexin V(+) NK cells cultured with IL-15 was lower than that with IL-2; moreover, most of Annexin V(+) NK cells were primarily in the CD56(dim) NK cells. IL-15 cultured NK cells expressed higher level of Bcl-xL than IL-2 cultured cells. Furthermore, IL-15 more strongly upregulated CD25 expression and better maintained the expression of IL-15Ralpha than IL-2. These results suggest that CD56(dim) NK cells undergo apoptosis when cultured with IL-2, but IL-15 inhibits their apoptosis and Bcl-xL is associated with the anti-apoptotic effect of IL-15. So IL-15 played a crucial role in sustaining long-lasting functions of CD56(dim) NK cells.     

IL-21 induces both rapid maturation of human CD34+ cell precursors towards NK cells and acquisition of surface killer Ig-like receptors

The NK cell maturation from CD34(+) Lin(-) hematopoietic cell precursors is a complex process that requires the direct contact with stromal cells and/or the synergistic effect of different cytokines. In this study we show that IL-21 is capable of inducing an accelerated NK cell maturation when added to cultures of CD34(+) Lin(-) cells isolated from human cord blood supplemented with IL-15, Flt3-L and SCF. After 25 days of culture, 50% of CD56(+) cells expressed various NK cell markers including the NKp46 and NKp30 triggering receptors, the CD94/NKG2A inhibitory receptor and CD16. At day 35, substantial fractions of NK cells expressed KIR, CD8 and CD2, i.e. surface markers expressed by mature NK cells, that are virtually undetectable in developing NK cells cultured in the absence of IL-21. Remarkably, similar to mature NK cells all these markers were included in the CD56(dim) cell fraction, while the CD56(bright) population was only composed of CD94/NKG2A(-) and CD94/NKG2A(+) cells. Thus, IL-21 allows the induction of a full NK cell maturation in vitro and offers an important tool for dissecting the molecular mechanisms involved in different steps of NK cell maturation and in the acquisition of a mature KIR repertoire.     

Generation of natural killer cells from serum-free, expanded human umbilical cord blood CD34+ cells

Natural killer (NK) cells are important effectors of the innate immune system, which exhibits cytolytic activity against infectious agents and tumor cells. NK cells are derived from CD34(+) hematopoietic stem cells (HSCs). Human umbilical cord blood (UCB) has been recognized as a rich source of HSCs. Previously, we have reported an optimized serum-free medium for ex vivo expansion of CD34(+) cells from UCB. In this study, the serum-free, expanded CD34(+) cells were tested to differentiate into NK cells and their induction kinetics. After 5 weeks of induction, the induced NK cells were characterized by analysis of surface antigens, IFN-gamma secretion, and cytotoxicity against K562 cells. The results indicated that NK cells derived from the serum-free, expanded CD34(+) cells exhibited both characteristics and functions of NK cells. Furthermore, the serum-free, expanded CD34(+) cells showed a significantly higher NK cell differentiation potential than freshly isolated CD34(+) cells. NK cells induced from serum-free, expanded CD34(+) cells showed a higher concentration of IFN-gamma secretion and ability of cytotoxicity than those from freshly isolated CD34(+) cells. Therefore, ex vivo-expanded CD34(+) cells in optimized serum-free medium could differentiate into NK cells and provided a promising cell source for immunotherapeutic approaches.