不明原因自然流产与蜕膜NK细胞表面活化性受体表达的相关性研究

探讨不明原因自然流产患者蜕膜NK细胞杀伤活性与其细胞表面活化性受体NKp46、NKp44、NKp30和NKG2D表达的相关性。选取21例早孕不明原因自然流产患者为病例组,25例正常早孕人流妇女为对照组,收集两组的蜕膜组织,Ficoll密度梯度离心分离淋巴细胞,MACS磁珠分选CD3-CD56+NK细胞。以K562细胞为靶细胞,用细胞染色及流式细胞技术检测两组蜕膜NK细胞杀伤活性,用流式细胞技术检测两组蜕膜CD56brightCD16-NK和CD56dimCD16+NK细胞上活化性受体NKp46、NKp44、NKp30和NKG2D的表达,并与NK细胞杀伤活性进行相关性分析。结果:(1)早孕蜕膜NK细胞具有杀伤活性;(2)病例组蜕膜NK细胞的杀伤活性较正常对照组显著增强(P=0.014);(3)病例组蜕膜CD56brightCD16-NK细胞中NKp44的表达比正常对照组显著升高(P=0.021);病例组蜕膜CD56dimCD16+NK细胞中NKp46和NKp44的表达比正常对照组显著升高(分别P=0.026,P=0.041);其余活化性受体的表达两组未见明显差异;(4)蜕膜NK细胞杀伤功能与蜕膜CD56brightCD16-NK细胞中NKp44的表达呈显著正相关(r=0.677,P<0.05),和蜕膜CD56dimCD16+NK细胞中NKp46的表达呈显著正相关(r=0.634,P<0.05)。蜕膜NK细胞活化性受体NKp46和NKp44表达增加,从而使蜕膜NK细胞的杀伤功能增强可能在不明原因自然流产的发病中起重要作用。     

CD59 is physically and functionally associated with natural cytotoxicity receptors and activates human NK cell-mediated cytotoxicity

Triggering of cytotoxicity in human NK cells is induced by the combined engagement of several triggering receptors. These include primary receptors such as NKG2D and the natural cytotoxicity receptors (NCR) NKp30, NKp46 and NKp44, while other molecules, including 2B4, NTB-A and NKp80, function as co-receptors. As reported in the present study, during an attempt to identify novel NK receptors or co-receptors, we found that CD59 functions as a co-receptor in human NK cell activation; engagement of CD59 by specific mAb delivers triggering signals to human NK cells, resulting in enhancement of cytotoxicity. Similar to other NK co-receptors, the triggering function of CD59, a glycosylphosphatidylinositol (GPI)-linked protein, depends on the simultaneous engagement of primary receptors such as NCR. Accordingly, CD59-dependent triggering was virtually restricted to NK cells expressing high surface densities of NKp46, and mAb-mediated modulation of NKp46 resulted in markedly decreased responses to anti-CD59 mAb. Biochemical analysis revealed that CD59 is physically associated with NKp46 and NKp30. Moreover, engagement of CD59 resulted in tyrosine phosphorylation of CD3zeta chains associated with these NCR, but not those associated with CD16. Thus, CD59-mediated costimulation of NK cells requires direct physical interaction of this GPI-linked protein with primary triggering NK receptors.     

Recognition of viral hemagglutinins by NKp44 but not by NKp30

Natural killer (NK) cells destroy virus-infected and tumor cells without prior antigen stimulation. The NK cell cytotoxicity is regulated in large part by the expression of NK cell receptors that are able to bind major histocompatibility complex (MHC) class I glycoproteins. NK cells also express lysis triggering receptors specific for non-MHC ligands, including NKp30, NKp44, NKp46 and CD16. However, the nature of their ligands, recognized on target cells, is undefined. We have recently shown that the NKp46 protein, but not the CD16 protein, recognizes the hemagglutinin (HA) of influenza virus (IV) and the hemagglutinin-neuraminidase (HN) of Sendai virus (SV), and that the recognition of HA from IV requires the sialylation of NKp46 oligosaccharides. We have also demonstrated that binding of NKp46 to HA of IV is required for lysis of cells expressing the corresponding glycoproteins by a substantial subset of NK clones. Here we show that NKp44, but not NKp30, can also recognize the HA of both IV and SV and that the recognition of IV HA requires the sialylation of the NKp44 receptor in a similar way to that of NKp46. SV infection of 721.221 cells expressing MHC class I proteinsresulted in the abrogation of the inhibition by NK clones expressing high levels of NKp44. In addition, the binding of NKp44 to HA improves the ability of some NK clones to lyse IV infected cells.     

Activation of natural killer cells by hepatitis C virus particles in vitro

Little is known about the ability of hepatitis C virus (HCV) to alter early innate immune responses in infected patients. Previous studies have shown that natural killer (NK) cells are functionally impaired after interaction of recombinant HCV glycoprotein E2 with the co-stimulatory CD81 molecule in vitro; however, the functional consequences of a prolonged contact of NK cells with HCV particles have remained unclear. We have examined the phenotypes of purified, interleukin-2-activated NK cells from healthy donors and HCV genotype 1b patients after culture for 5 days with HCV pseudoparticles (HCVpp) and serum samples containing HCV genotype 1b. NK cells from healthy donors and chronic HCV patients were found to up-regulate receptors associated with activation (NKp46, NKp44, NKp30, NKG2D), while NK receptors from the killer cell immunoglobulin-like receptor family (KIR/CD158), predominantly having an inhibitory function, were significantly down-modulated after culture in the presence of HCV particles compared with control cultures of NK cells. HCV-infected sera and HCVpp elicited significantly higher secretion of the NK effector lymphokines interferon-γ and tumour necrosis factor-α. Furthermore, HCV stimulated the cytotoxic potential of NK cells from normal donors and patients. The enhanced activation of NK cells after prolonged culture with HCVpp or HCV-containing sera for 5 days suggests that these innate effector cells may play an important role in viral control during early phases of HCV infection.     

Separation Methods of T Cells,Natural Killer,and Dendritic Cells from Peripheral Blood of Cancer Patients using Interleukin-2 and Functional Analysis of Natural Killer Cells after Separation

We aimed to induce three different immune cell subsets from a single blood sample from cancer patients to target different biological characters of cancer cells. In the presence of 6000 IU/ml IL-2, natural killer (NK) cells adhere to plastic. By using this ability, we could separate dendritic cells, T cells, and NK cells from peripheral blood mononuclear cells. The cultured NK cells demonstrated higher nonspecific cytotoxicity against tumor cell lines than did the T cells. Furthermore, adherent NK cells demonstrated higher cytotoxicity than nonadherent NK cells, although there was no difference between adherent and nonadherent NK cells in natural cytotoxicity receptors (NKp30, NKp44, NKp46) and NKG2D expression. With these results, we confirmed that we could induce dendritic cell, T cell, and higher cytotoxic NK cells from a single blood draw, and this methodology facilitates to the use of these cells for clinical grade conditions.     

Separation methods of T cells, natural killer, and dendritic cells from peripheral blood of cancer patients using interleukin-2 and functional analysis of natural killer cells after separation

We aimed to induce three different immune cell subsets from a single blood sample from cancer patients to target different biological characters of cancer cells. In the presence of 6000 IU/ml IL-2, natural killer (NK) cells adhere to plastic. By using this ability, we could separate dendritic cells, T cells, and NK cells from peripheral blood mononuclear cells. The cultured NK cells demonstrated higher nonspecific cytotoxicity against tumor cell lines than did the T cells. Furthermore, adherent NK cells demonstrated higher cytotoxicity than nonadherent NK cells, although there was no difference between adherent and nonadherent NK cells in natural cytotoxicity receptors (NKp30, NKp44, NKp46) and NKG2D expression. With these results, we confirmed that we could induce dendritic cell, T cell, and higher cytotoxic NK cells from a single blood draw, and this methodology facilitates to the use of these cells for clinical grade conditions.     

Expression of killer immunoglobulin-like receptors on peripheral blood NK cell subsets of women with recurrent spontaneous abortions or implantation failures

PROBLEM: Decidual natural killer (NK) cells express inhibitory receptors (killer immunoglobulin-like receptors, KIRs), which bind to ligands on trophoblast cells (human leucocyte antigen, HLA-C). This interaction appears to block NK cytotoxicity against trophoblast cells. In this study, we investigated the expression of inhibitory and activating receptors in peripheral blood NK cells of women with recurrent spontaneous abortion (RSA) or implantation failures. METHOD OF STUDY: CD56(dim)/CD16(+), CD56(bright)/CD16(-) NK cells and CD56(+)/CD3(+) NKT cells of women with RSA or in vitro fertilization (IVF) failures and normal controls were analyzed for the expression of CD158a, CD158b inhibitory KIRs or CD161-activating receptors, by flow cytometric analysis. RESULTS: CD158a and CD158b inhibitory receptor expression by CD56(dim)/CD16(+) and CD56(bright)/CD16(-) NK cells were significantly decreased, and CD161-activating receptor expression by CD56(+)/CD3(+) NKT cells was significantly increased in women with implantation failures when compared with normal controls. CONCLUSIONS: An imbalance between inhibitory and activating receptor expression was found in NK cells of women with implantation failures. This imbalance may explain the adverse reproductive outcome.     

Increased killer immunoglobulin-like receptor expression and functional defects in natural killer cells in lung cancer

Frequencies of natural killer (NK) cells from patients with non-small cell lung cancer (NSCLC) or small cell lung cancer (SCLC) did not differ from healthy controls. A higher proportion of NK cells from NSCLC patients expressed the killer immunoglobulin-like receptor (KIR) CD158b than in controls (P = 0.0004), in the presence or absence of its ligand, HLA-C1. A similar result was obtained for CD158e in the presence of its ligand HLA-Bw4 in NSCLC patients (P = 0.003); this was entirely attributable to the Bw4I group of alleles in the presence of which a fivefold higher percentage of CD158e(+) NK cells was found in NSCLC patients than controls. Proportions of CD158b(+) NK cells declined with advancing disease in NSCLC patients. Expression of NKp46, CD25 and perforin A, and production of interferon-γ following stimulation with interleukin-12 and interleukin-18, were all significantly lower in NK cells from NSCLC patients than in controls. Both NK cell cytotoxicity and granzyme B expression were also reduced in lung cancer patients. Increased inhibitory KIR expression would decrease NK cell cytotoxic function against tumour cells retaining class I HLA expression. Furthermore, the reduced ability to produce interferon-γ would restrict the ability of NK cells to stimulate T-cell responses in patients with lung cancer.     

Age-related changes in natural killer cell receptors from childhood through old age

Most studies on natural killer (NK) cells and aging have focused on overall cell numbers and global cytotoxic activity. NK cell functions are controlled by surface receptors belonging to three major families: killer cell immunoglobulin-like receptors (KIRs), natural cytotoxicity receptors (NCRs), and C-type lectins. The expression of these receptors was investigated from childhood through old age in T, NKT- and NK cells and also in the CD56(dim) (cytotoxic) and CD56(bright) (responsible for cytokine production) NK cell subsets. A decrease in the expression of activating receptors (NKp30 and NKp46) was observed in NK cells in elderly individuals. KIR expression was increased only in the CD56(bright) subset. Children presented similar results regarding expression of NKp30 and KIR, but not NKp46. NKG2D expression was decreased in T cells of elderly subjects. Analysis of KIR genotype revealed that KIR2DL5 and KIR2DS3 were significantly associated with old age. Cytotoxic activity was preserved from childhood through old age, suggesting that the increase of the absolute number of CD56(dim), observed in elderly, may represent a compensatory mechanism for the receptor expression alterations. This initial study provides the framework for more focused studies of this subject, which are necessary to determine whether the changing balance of NK receptor expression may influence susceptibility to infectious, inflammatory, and neoplastic diseases.     

Differential expression of natural killer cell activating receptors in blood versus bone marrow in patients with monoclonal gammopathy

In monoclonal gammopathies (MG) and multiple myeloma (MM), normal natural cytotoxicity receptors (NCR) expression (NCR1/NKp46, NCR2/NKp44, NCR3/NKp30) is observed in natural killer (NK) cells. Nonetheless, except in plasma cell leukemia, few tumor plasmocytes are present in PB, while NK studies have been performed on peripheral blood (PB). For this reason we focused our attention on NK from bone marrow (BM). Our study demonstrates that the down‐regulation of NCR3/NKp30 is only detectable in NK from BM but not in PB, and shows a drastic decrease of both NKG2D and CD244/2B4/p38 expression in NK from BM in comparison with PB. In conclusion, our data more precisely describe the mechanism of immune escape of MG/MM from innate immunity since we show a drastic down regulation of 3 major activating NK receptors (NCR3/NKp30, NKG2D and CD244/2B4/p38) at the site of tumor, i.e BM, that was undetectable in PB. Further studies regarding immune regulatory drugs in MG/MM will imperiously require the assessment of immune cell status not only in PB but also in BM to obtain more relevant data regarding anti‐tumor efficacy.     

Expression of natural cytotoxicity receptors and a2V-ATPase on peripheral blood NK cell subsets in women with recurrent spontaneous abortions and implantation failures

PROBLEM: Natural cytotoxicity receptors (NCRs) are unique markers, which regulate NK cell cytotoxicity and cytokine production. a2V-ATPase is expressed on subsets of PBMC and regulates the extracellular environment, which facilitates NK cytotoxicity or cytokine secretion. In this study, we aim to investigate the expression of NCRs and a2V-ATPase in peripheral blood NK cells of women with recurrent spontaneous abortions (RSA) or implantation failures. METHOD OF STUDY: Peripheral blood NK cells (CD56(dim) and CD56(bright) were analyzed for the expression of NCRs (NKp46, NKp44 and NKp30) and a2V-ATPase using 3-color flow cytometry in women with RSA (n=24), implantation failures (n=19) or normal healthy women (n=13). RESULTS: CD56+/NKp46+ cells were markedly decreased (P<0.05) and CD56(bright)/a2V-ATPase+ cells were significantly increased (P<0.05) in women with RSA as compared to those of normal controls. In women with RSA or implantation failures, expression of NKp46, NKp44, NKp30, and a2V-ATPase on CD56(bright) NK cells was significantly up-regulated as compared with those of CD56(dim) NK cells. CONCLUSION: The differential expression of NCRs and a2V-ATPase in NK cell subsets may suggest dysregulation of NK cytotoxicity and cytokine production in women with RSA and implantation failures.     

Peritoneal natural killer cells from epithelial ovarian cancer patients show an altered phenotype and bind to the tumour marker MUC16 (CA125)

The ovarian tumour marker MUC16 (CA125) inhibits the cytotoxic responses of human natural killer (NK) cells and down-regulates CD16. Here we show that approximately 10% of the peripheral blood NK cells (PBNK) from the epithelial ovarian cancer (EOC) patients are CD16(-) CD56(br) whereas 40% of the peritoneal fluid NK (PFNK) carry this phenotype, which is usually associated with NK cells from the lymph nodes or human decidua. PBNK from healthy donors exposed to PF show a significant increase in the CD16(-) CD56(br) population. This shift in phenotype is not caused by increased apoptosis of the CD16(+) CD56(dim) cells or selective proliferation of the CD16(-) CD56(br) NK cells. Thus, the terminal differentiation of the CD16(-) CD56(br) NK cells to CD16(+) CD56(dim) subset that occurs during normal NK cell development may actually be a reversible step. A majority of the NK cell receptors (NKp46, NKp44, NKG2D, CD244, CD226, CD158a, CD158b, and CD158e) studied were down-regulated in the PFNK. MUC16 binds selectively to 30-40% of CD16(+) CD56(dim) NK cells in EOC patients indicating that phenotypic alterations in these cells are mediated by tumour-derived soluble factors. Similar to EOC, MUC16 in early pregnancy also binds to NK cells suggesting shared mechanisms of NK cell suppression in feto-maternal tolerance and immune evasion by ovarian cancers.     

Bovine natural killer cells acquire cytotoxic/effector activity following activation with IL-12/15 and reduce Mycobacterium bovis BCG in infected macrophages

Bovine natural killer (NK) cells were recently identified by positive selection of a NK cell-activating receptor p46 (NKp46)+ CD3- lymphocyte population, which expresses CD25 and CD8 and lyses tumor cell lines following stimulation with recombinant interleukin-2. In the current work, we characterize the cytotoxic/effector potential of a CD3(-)CD8(-)CD11b- population isolated through negative selection of bovine peripheral blood leukocytes. This population is CD25(lo)CD62(hi) when isolated and becomes CD25hiCD62L(lo) following cytokine stimulation. Activated bovine NK cells increase expression of granulysin, interferon-gamma, and perforin and have cytotoxic activity against human tumor cells and Mycobacterium bovis bacillus Calmette-Guerin-infected alveolar and monocyte-derived macrophages. Expression of a bovine homologue of the CD56 neural adhesion molecule expressed by human NK cells was detected in mRNA from brain tissue but was not detected in peripheral blood mononuclear cells or purified NK cell mRNA. Analysis of mRNA from nonstimulated peripheral blood NK cells demonstrates the constitutive expression of homologues of human NK receptors NKp46, CD244, and CD94 and the granule proteins granulysin and perforin. Phorbol ester-stimulated CD8+ T cells also expressed CD244 and CD94, and CD4+ T cells expressed CD94. These NK cell receptors bearing T lymphocytes may represent memory subsets characterized in humans. The results of these studies demonstrate that bovine NK cells may play an important role in the innate immune responses of cattle.     

The corticosteroid-induced inhibitory effect on NK cell function reflects down-regulation and/or dysfunction of triggering receptors involved in natural cytotoxicity

Corticosteroids are known to inhibit NK cell functions. However no information is available on whether such inhibition may affect the expression and/or the function of receptors involved in NK cell activation. In an attempt to analyze this point, we studied peripheral blood NK cells isolated from pediatric patients undergoing allogeneic BM transplantation. NK cells were analyzed before, during and after methylprednisolone administration to treat acute graft-versus-host disease. In NK cells freshly isolated from peripheral blood during methylprednisolone treatment, the surface expression of activating receptors, particularly NKp46 and NKp30, was consistently reduced. Such impaired expression could also be detected after 5 days of culture in IL-2. Such cultured NK cells also failed to express the IL-2-inducible NKp44 receptor. Accordingly, cytotoxicity against different tumor target cell lines was sharply reduced. The effect on NK cells isolated from healthy individuals and cultured in the presence of methylprednisolone was also analyzed. A similar inhibitory effect occurred in the expression of activating NK receptors. In addition, a sharp impairment of NK cytotoxicity against different tumor target cell lines or immature DC was detected.     

Siglec‐7 Defines a Highly Functional Natural Killer Cell Subset and Inhibits Cell‐Mediated Activities

Sialic acid‐binding immunoglobulin‐like lectin‐7 (Siglec‐7) is an inhibitory receptor expressed on natural killer (NK) cells. In this study, we investigated the relationship between Siglec‐7 expression and NK cell functions. Siglec‐7 was highly expressed on NK cells and was preferentially expressed by mature NK cells from peripheral blood of healthy adults. Siglec‐7⁺ NK cells displayed higher levels of activating receptors CD38, CD16, DNAM1, NKp30 and NKp46, but lower levels of inhibitory receptors such as NKG2A and CD158b, compared with Siglec‐7^– NK cells. Functional tests showed that Siglec‐7⁺ NK cells displayed more CD107a degranulation and IFN‐γ production than Siglec‐7^– NK cells. Siglec‐7 inhibited NK cell functions when interacting with specific antibodies. These data suggest that Siglec‐7 defines a highly functional NK cell subset and suppresses NK cell‐mediated functions when cross‐linked with specific antibodies.     

Identification of novel single nucleotide substitutions in the NKp30 gene expressed in human natural killer cells

Cytotoxicity of natural killer (NK) cells is regulated by a balance of signals from two kinds of NK receptors, activating receptors and inhibitory receptors. Natural cytotoxicity receptors (NCR) family, which consists of NKp30, NKp44 and NKp46, is a major human activating NK receptor. NKp30 has been mapped to the HLA class III region near tumor necrosis factor (TNF) family loci. We have analyzed the NKp30 gene of healthy Japanese and found two synonymous substitutions in the coding region, c.111G>A and c.156C>T, and also identified two single-nucleotide polymorphisms (SNPs) in the promotor region, -201G>A and -163G>C. Furthermore, it was confirmed that these polymorphisms of the NKp30 gene show strong linkage disequilibria with each other and with HLA-DRB1 or TNFA polymorphisms. Since susceptibilities to certain diseases were mapped near this region, the NKp30 polymorphisms could be useful genetic markers.     

NKp46 is the major triggering receptor involved in the natural cytotoxicity of fresh or cultured human NK cells. Correlation between surface density of NKp46 and natural cytotoxicity against autologous, allogeneic or xenogeneic target cells.

NKp46 is a novel triggering receptor expressed by all human NK cells that is involved in natural cytotoxicity. In this study we show that the surface density of NKp46 may vary in different NK cells and that a precise correlation exists between the NKp46 phenotype of NK clones and their natural cytotoxicity against HLA-class I-unprotected allogeneic or xenogeneic cells. Thus, NKp46bright clones efficiently lysed human and murine tumor cells while NKp46dull clones were poorly cytolytic against both types of target cells. We also show that the NKp46 phenotype of NK clones correlates with their ability to lyse HLA-class I-unprotected autologous cells. Finally, NKp46 was found to be deeply involved in the natural cytotoxicity mediated by freshly derived NK cells. This was indicated both by the inhibition of cytolysis after monoclonal antibody-mediated masking of NKp46 and by the correlation existing between the natural cytotoxicity of fresh NK cells derived from different donors and their NKp46 phenotype. In conclusion, these studies strongly support the concept that NKp46 plays a central role in the physiological triggering of NK cells and, as a consequence (in concert with killer inhibitory receptors), in the NK-mediated clearance of abnormal cells expressing inadequate amounts of HLA-class I molecules.