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Problem Trophoblasts are known to decrease natural killer ( NK) cell cytotoxicity. However, little is known about the interaction between trophoblasts and NK cells during pregnancy. Interleukin-15 ( IL-15) is essential for priming NK cells and maximizing their effector functions. We investigated whether trophoblasts regulate NK cell activation via IL-15/ IL-2 receptor and its signaling pathways. Method of study Natural killer-92 cells were primed with human first-trimester trophoblast cells (Sw.71) conditioned medium ( CM) and co-cultured with K562 cells. Flow cytometry, Western blot analysis, and real-time PCR were performed to assess NK cell cytotoxicity, IL-15/ IL-2 receptor expression, phosphorylation of STAT5 and MAPKs, and mRNA expression of IL-15-related genes. Results Natural killer-92 cells incubated with Sw.71 CM showed reduced cytotoxicity and IL-15-mediated proliferation, and expression of IL-15/ IL-2 receptor subunits. STAT5 phosphorylation, EOMES and T-bet mRNA expressions, and ERK/ JNK pathways of NK 92 cells were suppressed by Sw.71 CM. Productions of perforin, granzyme B, and IFN-γ were also downregulated. Conclusion Trophoblasts regulate human NK cell functions via suppression of IL-15/ IL-2 receptor expression, transcription factors, and ERK/ JNK pathways. [ABSTRACT FROM AUTHOR]

Natural killer (NK) cells are innate immune effector cells that protect against cancer and some viral infections. Until recently, most studies have investigated the molecular signatures of human or mouse NK cells to identify genes that are specifically expressed during NK cell development. However, the mechanism regulating NK cell development remains unclear. Here, we report a regulatory network of potential interactions during in vitro differentiation of human NK cells, identified using genome-wide mRNA and miRNA databases through hierarchical clustering analysis, gene ontology analysis and a miRNA target prediction program. The microRNA (miR)-583, which demonstrated the largest ratio change in mature NK cells, was highly correlated with IL2 receptor gamma (IL2Rγ) expression. The overexpression of miR-583 had an inhibitory effect on NK cell differentiation. In a reporter assay, the suppressive effect of miR-583 was ablated by mutating the putative miR-583 binding site of the IL2Rγ 3′ UTR. Therefore, we show that miR-583 acts as a negative regulator of NK cell differentiation by silencing IL2Rγ. Additionally, we provide a comprehensive database of genome-wide mRNA and miRNA expression during human NK cell differentiation, offering a better understanding of basic human NK cell biology for the application of human NK cells in immunotherapy. [ABSTRACT FROM AUTHOR]

Abstract: Natural killer (NK) cells are differentiated from hematopoietic stem cells (HSCs) which are located at the lowest end of an oxygen gradient within the bone marrow (BM). In this report, we investigated whether oxygen tension could affect NK cell differentiation from hematopoietic cells in vitro. We found that hypoxia led to an inhibition of differentiation in NK cells, and increased oxygen supply alleviated this inhibition and restored NK cell differentiation under hypoxic condition. Hypoxia-treated cells demonstrated reduced mRNA expression of transcription factors (TFs) that have important roles in NK cell differentiation, such as EOMES, T-bet, GATA-3 and ETS-1. Moreover, hypoxia-pretreated cells recovered mRNA expression of TFs when the oxygen tension was changed to normoxia. Our findings suggest that oxygen tension modulates in vitro differentiation of NK cells through the regulation of TF expression. [Copyright &y& Elsevier]

Abstract: Natural killer (NK) cells act important roles in innate immunity and adaptive immunity. However, the mechanisms governing NK cell development have not been clearly elucidated. Previous studies have shown that an HMG (high-mobility group) protein, TOX, is important for regulating the differentiation program of developing T cells in mice. In this study, we examined the role of TOX in differentiation of human NK cells. Knockdown of TOX in differentiating cells decreased the NK cell population identified by expression of NK surface markers and receptors. In addition, over-expression of TOX enhanced the differentiation of NK cells which give rise to a population showing effector functions of mature NK cells. Moreover, TOX influenced expression of T-bet (T-box expressed in T cells, also as known as Tbx21) during NK cell development. Overall, these results suggest that TOX is required for IL-15-mediated NK cell differentiation and affected expression of T-bet that plays critical roles in NK differentiation and maturation. [Copyright &y& Elsevier]

Abstract: NK cells play crucial roles in innate immunity and adaptive immunity. The detailed mechanisms, however, governing NK cell development remains unclear. In this study, we report that YC-1 significantly enhances NK cell populations differentiated from human umbilical cord blood hematopoietic stem cells (HSCs). NK cells increased by YC-1 display both phenotypic and functional features of fully mature NK (mNK) cells, but YC-1 does not affect the activation of mNK cells. YC-1 did not affect cGMP production and phosphorylation of STAT-5 which is essential for IL-15R signaling. On the other hand, YC-1 increased p38 MAPK phosphorylation during NK cell differentiation. Furthermore, p38 inhibitor SB203580 inhibited the differentiation of NK cells enhanced by YC-1. Taken together, these data suggest that YC-1 enhances NK cell differentiation through the activation of p38 MAPK which is involved in NK cell differentiation. [Copyright &y& Elsevier]

Perforin (Prf1) and granzyme B (GzmB) are essential effector molecules for natural killer (NK)-cell cytotoxicity, but how Prf1 and GzmB expression is regulated during arming of NK cells is poorly defined. We show that human microRNA (miR)-27a* is a negative regulator of NK-cell cytotoxicity by silencing Prf1 and GzmB expression. Human miR-27a* specifically bound to the 3' untranslated regions of Prf1 and GzmB, down-regulating expression in both resting and activated NK cells, and it functioned as a fine-tuner for homeostasis of the net amount of the effector proteins. Consistent with miR-27a* having an inhibitory role, knockdown of miR-27a* in NK cells dramatically increased cytotoxicity in vitro and decreased tumor growth in a human tumor xenograft model. Thus, NK-cell cytotoxicity is regulated, in part, by microRNA, and modulating endogenous miR-27a* levels in NK cells represents a potential immunotherapeutic strategy. [ABSTRACT FROM AUTHOR]

Abstract: The IL-22 NKp46+ innate lymphoid cells, NCR22 cells, are very important for the early host defense against microbial pathogens. We show here that NCR22 cells were differentiated from Lin−CD127+CD117+ cells that were derived from hematopoietic precursor cells (HPCs) of mouse bone marrow cells. The combination of low concentrations of IL-23 and IL-15 induced differentiation of NCR22 cells from Lin−CD127+CD117+ cells. NCR22 cells expressed a large amount of IL-22 and RORγt, and they had poor cytolytic activity and produced little IFN-γ. Lin−CD127+CD117+ cells were very similar to intestinal lamina propria LTi-like cells; both cells dominantly expressed RORγt and IL-22. Meanwhile, Lin−CD127−CD117+ cells that were also derived from HPCs did not express RORγt and IL-22, and they developed into conventional NK cells, not into NCR22 cells. These findings revealed that NCR22 cells can be differentiated from Lin−CD127+CD117+ cells which are derived from HPCs. [Copyright &y& Elsevier]