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.     

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.     

Natural killer (NK) cell subsets and NK cell cytotoxicity in women with histories of recurrent spontaneous abortions

PROBLEM: Natural Killer (NK) cell measurement and NK cytotoxicity are two measurements for assessing the cellular immune response. Both of the techniques have been reported to be prognostic for women with recurrent spontaneous abortion (RSA), We evaluated the two methods to determine the relationship of the two assays. Because both methods portend to evaluate the same process, the previous clinical data suggested that the methods evaluate the same phenomena. We undertook these studies to determine whether simple NK cell counts may be sufficient in the evaluation of NK activity in RSA. METHOD OF STUDY: The NK cell cytotoxicity at effector-to-target ratios of 50:1 and 25:1 was determined using a flow cytometric NK cell cytotoxicity assay. These values were then correlated with the percentages and absolute counts of three peripheral blood NK cell subsets. RESULTS: The data indicate that the flow cytometric assay is reproducible and precise and can be successfully used to evaluate patient samples. Linear regression analysis indicated a lack of correlation between peripheral blood NK cell cytotoxicity and percentages or absolute counts of ***CD56+CD16+, CD56+CD16 — or CD3+CD56+ lymphocyte subsets (range of correlation coefficients, 0.1–0.3). CONCLUSIONS: NK cell cytotoxicity and peripheral blood NK cell values measure different aspects of NK cells and do not correlate. These data indicate that simple enumeration of NK cells may not be sufficient in the evaluation of NK cells in RSA.     

Natural killer (NK) cell receptors' repertoire in couples with recurrent spontaneous abortions

PROBLEM: Natural killer (NK) cell receptors (NKRs) have been suggested to protect trophoblast, but their function at the fetomaternal interface remains unknown. To investigate if the outcome of pregnancy depends on women's NKRs, we studied the NKR repertoire in couples with recurrent spontaneous abortions (RSA). METHODS: Twenty-six childless couples with > or = 2 abortions, characterized by alloimmune abnormalities, and 26 control couples were genotyped for five killer immunoglobulin-like receptors (KIR) and two CD94/NKG receptors, known to have as ligands human leukocyte antigen (HLA) class I molecules with trophoblastic expression: inhibitory 2DL1,2,3 and activating 2DS1,4 KIRs, inhibitory NKG2A and activating NKG2C. Detected repertoires of women and partners were compared between the two groups. RESULTS: Less aborters than controls were found to have all three inhibitory KIRs (30.77% versus 69.23%, P = 0.01), some of them had only one inhibitory KIR (19.23% versus 3.85%, P = 0.08) and most of them were lacking inhibitory KIRs possessed by their husbands (57.69% versus 15.38%, P = 0.001). CONCLUSIONS: Women with alloimmune abortions have a limited inhibiting KIR repertoire and such miscarriages may occur because trophoblastic HLA class I molecules are recognized by decidual NK cells lacking the appropriate inhibitory KIRs.     

Status of peripheral blood natural killer cells in women with recurrent spontaneous abortions and infertility of unknown aetiology

The aim of this study was to investigate the functional status and immunophenotypic characteristics of natural killer (NK) cells in women who suffer recurrent spontaneous abortions (RSA) or have infertility of unknown aetiology. Peripheral blood mononuclear cells (PBMC) were obtained from 40 study patients and 13 normal healthy multiparous controls. NK cells were identified using anti-CD56 and anti-CD16 monoclonal antibodies (mAb). The expression of CD69, CD25, CD122, CD30, CD154, CD128 and CD94 on NK cells was detected using specific mAb and analysed by flow cytometry. CD69 expression on NK cells after ED(27) human trophoblast cell line co-culture with PBMC was also investigated. A significant increase in CD69 expression on CD56(+) NK cells was demonstrated in women with RSA (P < 0.005) and infertility (P < 0.05) as compared with that of normal controls. Conversely, CD94 expression was significantly decreased in women with RSA (P < 0.005) and infertility (P < 0.05) in comparison with that of controls. Increased CD69 expression on NK cells was induced after 24 h co-culture with ED(27). In conclusion, peripheral blood NK cells of women with RSA and infertility of unknown aetiology have higher proportions of activated NK cells in vivo. Unbalanced CD69 and CD94 expression may explain the underlying pathology.     

T helper 1 and 2 cytokine expression in women with recurrent spontaneous abortions and infertility of repeated implantation failures

Normal pregnancy is proposed to be a T helper (Th) 2 immune response. Th2 cells induce antibody mediated immunity and secrete cytokines such as IL-4, 5 and 10, which favors a successful pregnancy. A few studies are reported to investigate Th1 or Th2 immune responses in women with reproductive failures. Recent advances in flow cytometric analysis enable us to detect presence of Th1 or Th2 immune response by isolating T cell subpopulations and defining their characteristics of intracellular cytokine expression. Women with recurrent spontaneous abortions (RSA) and infertility of multiple implantation failures after IVF/ET have significantly higher Th1/Th2 ratios as compared to normal fertile women. Intracellular TNF-α expression, TNF-α/IL-4 and TNF-α/IL-10 ratios in CD3+/CD4+ T cells are significantly different in women with implantation failure who got pregnant, who failed to get pregnant and normal fertile women. When the absolute cell counts of cytokine expressing cells are examined, women with RSA and implantation failures demonstrated significantly higher TNF-α expressing CD3+/CD4+ T cells and lower IL-10 expressing CD3+/CD8+ T cells than those of normal fertile controls. In conclusion, women with RSA and infertility of implantation failures demonstrate a Th1 biased immune response. Further molecular genetic study of Th1 and Th2 cytokines may shed the light to understand possible etiologies for dysregulation Th1/Th2 immune responses.     

反复性自然流产患者MTHFR基因的多态性研究

目的检测反复性自然流产（recurrent spontaneous abortion，RSA）≥2次患者亚甲基四氢叶酸还原酶（methylenetetmhydrofolate reductase，MTHFR）基因位点C677T的出现频率，分析其与RSA发生的可能关系。方法采用聚合酶链反应-限制性片段长度多态（PCR—RFLP）技术检测80例RSA患者和60例正常妇女MTHFR基因C677T位点的分布和频率。结果在MTHFR基因突变分型中，RSA组T／T型以及C／T＋T／T型出现频率显著高于对照组。对照组C／C型频率显著高于患者组；单纯C／T型两组没有显著性差异。结论MTHFR基因位点突变以及部分HLA—DR基因位点与RSA发生有关。     

Thyroid autoantibodies in euthyroid non-pregnant women with recurrent spontaneous abortions

This study was undertaken to evaluate the incidence of thyroidautoantibodies in women with a history of recurrent (three ormore consecutive) spontaneous abortions. A total of 22 euthyroidnon-pregnant habitual aborters were analysed for thyreoglobulinand thyroid peroxidase antibodies; 22 nulligravidae and 22 multigravidaewithout endocrine dysfunction served as controls. Both thyroidantibodies were assayed using highly sensitive, commerciallyavailable enzyme-linked immunosorbent assay kits. Eight of the22 women with recurrent spontaneous abortions (36%) but onlytwo of the 22 nulligravidae controls (9%; ² test, P = 0.03)and one of 22 multigravidae subjects (5%; ² test, P < 0.01)demonstrated positive titres (> 100 IU/ml, as recommendedby the manufacturer) of thyreoglobulin, thyroid peroxidase orboth antibodies. The mean ± SD antibody concentrationswere 102.5 ± 226.5 in the study versus 20.9 ±68.8 in the nulligravidae (U-test, P = 0.057) and 26.4 ±60.2 IU/ml (P = 0.097) in the multigravidae population for thyroidperoxidase, and 47.7 ± 57.9 versus 24.1 ± 31.9(U-test, P = 0.051) and 28.1 ± 27.9 IU/ml (P = 0.059)for thyreoglobulin. In conclusion, the incidence of thyroidantibodies in euthyroid women with habitual abortions appearsto be significantly increased compared with the controls ofreproductive age without previous abortions. Although the importantissue of cause and effect has not been fully clarified, thisfinding suggests that thyroid antibodies may be a marker forautoimmune-mediated recurrent spontaneous abortions, not dissimilarto, for example, anticardiolipin.     

Expression of intracellular Th1 and Th2 cytokines in women with recurrent spontaneous abortion,implantation failures after IVF/ET or normal pregnancy

PROBLEM: We aimed to investigate absolute counts of intracellular T helper 1 (Th1) and Th2 cytokine expressing T-cell subpopulations in women with three or more recurrent spontaneous abortions (RSA), multiple implantation failures after in-vitro fertilization and embryo transfer (IVF/ET) (three or more) or during normal pregnancy. METHOD OF STUDY: Absolute cell counts and percentages of CD3+, CD3+/CD4+, and CD3+/CD8+ T-cell populations expressing intracellular cytokines [interferon-gamma (IFN-gamma), tumor necrosis factor-alpha (TNF-alpha), interleukin (IL)-4 and IL-10] was studied by four-color flow cytometry in 15 RSA and 13 implantation failure patients. Eighteen fertile non-pregnant and 47 normal pregnant women were also compared with regard to intracellular cytokine expression. RESULTS: Interleukin-10 producing CD3+/CD8+ T-cell counts were significantly lower in women with RSA (P < 0.05) and implantation failures (P < 0.05), and TNF-alpha producing CD3+/CD4+ T-cell counts were higher in women with RSA (P < 0.05) and implantation failures (P < 0.005) than those of non-pregnant fertile controls. During normal pregnancies, first trimester IL-4 expressing CD3+, CD3+/CD4+ T-cell counts (P < 0.05) and IFN-gamma expressing CD3+ T-cell counts (P < 0.05) were significantly higher than those of third trimester (P < 0.05). First trimester TNF-alpha expressing CD3+/CD8+ T-cell counts were significantly higher than those of second and third trimester women (P < 0.05). However, there are no differences in cytokine expression between non-pregnant and first trimester pregnant women. CONCLUSION: Absolute counts of IFN-gamma, IL-4, and TNF-alpha expressing T cells decrease with the progress of gestation (third trimester) during normal pregnancies. In women with implantation failures, absolute cell counts of TNF-alpha expressing CD3+/ 4- cells reflects the presence of dominant Th1 immune response. A significantly increased Th1 cytokine expression may be the underlying immune etiology for reproductive failures.     

Massive immunoglobulin treatment in women with four or more recurrent spontaneous primary abortions of unexplained aetiology

The aim of this trial was to investigate the efficacy of massive i.v. immunoglobulin (MIVIg) treatment for women with a history of recurrent spontaneous abortion (RSA) due to unexplained aetiology. The study included nine women (11 pregnancies) with a history of four or more consecutive RSA with unexplained aetiology and no live births. The mean number of fetal losses was 4.5 (range 4-6 abortions). Over the course of 5 days, immunoglobulin (20 g/day) was infused i.v. at gestational weeks 4-7. No additional infusions were carried out. Two pregnancies out of the 11 conceptions resulted in missed abortions at gestational weeks 6 and 7 respectively. Mosaicism (46XX/ 48XX, +16, +20), and tetraploidy (92XXXX) were found by chromosome analyses of the two aborti. Eight out of the other nine pregnancies resulted in full term deliveries of healthy neonates. One pregnancy developed intrauterine growth retardation and fetal distress, resulting in a premature delivery (30 gestational weeks) by Caesarean section. Thus, excluding the two abortions with chromosome aberrations, the MIVIg treatment was effective in all nine pregnancies of RSA women with unexplained aetiology. This MIVIg treatment (100 g administered in early gestation) may be a beneficial alternative to previous IVIg infusion methods, and should be further evaluated in a multicentric, placebo-controlled study, employing a larger number of homogeneous patients who fall into a high risk category of first trimester abortions.      

The human natural cytotoxicity receptors (NCR) that induce HLA class I-independent NK cell triggering

The cytolytic activity mediated by human natural killer (NK) cells is the result of a balance between signals delivered by inhibitory and activating receptors. The inhibitory receptors are represented by different families of HLA-specific receptors characterized by immunoreceptor tyrosine-based inhibiting motif(ITIM) sequences in their cytoplasmic portion. The function and the specificity of the inhibitory receptors imply the existence of triggering receptors specific for non-HLA ligands that are responsible for the induction of the cytolytic activity against HLA class I-deficient target cells. These receptors have remained elusive until recently when three distinct NK-specific molecules, termed natural cytotoxicity receptors (NCR), were identified and cloned. The different members of this novel family of receptors play a complementary role in the recognition and lysis of target cells. The NCR family is composed by a heterogeneous group of molecules belonging to the Ig superfamily that associate to different immunoreceptor tyrosine-based activating motif (ITAM)-containing signal transducing polypeptides.     

X chromosome aneuploidy in lymphocyte cultures from women with recurrent spontaneous abortions

Occasional metaphases with X chromosome aneuploidy can be detected in short-term lymphocyte cultures from women with recurrent abortions. The significance of this finding is unknown. It has been suggested that it may reflect a genetic tendency to nondisjunction that predisposes these women to an increased risk of producing aneuploid offspring. We have investigated prospectively the frequency of X chromosome aneuploidy in lymphocyte cultures from 104 women with a normal chromosome constitution and a history of recurrent pregnancy loss defined as 2 or more spontaneous abortions. Seventeen women (16%) had a significant number (2-10%) of X aneuploid cells in cultured lymphocytes but no evidence of constitutional chromosome mosaicism, based on analysis of fibroblast cultures. A control group of age-matched fertile women without a history of recurrent abortions showed a similar level of X chromosome aneuploidy in lymphocyte cultures. No increased risk for production of liveborn children with aneuploidy was found on retrospective analysis of the reproductive histories of these women. A significant effect of culture conditions on X chromosome gain or loss has been demonstrated by comparison of medium 199 with Dulbecco's modified Eagle medium.     

Analysis of human leukocyte antigen (HLA)-G polymorphism in normal women and in women with recurrent spontaneous abortions.

Human leukocyte antigen (HLA)-G is a non-classical class I antigen. It has limited expression, but is high at the foetomaternal interface. This unique expression pattern of HLA-G suggests that it might be important for survival of the foetus during pregnancy. In the present study, 120 women with recurrent spontaneous abortions (RSA) and 120 fertile control women were genotyped for the HLA-G locus. This is the first report describing HLA-G polymorphism in normal fertile and RSA women from India. The allele HLA-G*010103 was higher in women with recurrent foetal losses. Interestingly, the HLA-G*010105 and G*010108 alleles were totally absent in normal fertile women but present in RSA women with frequencies of 1.7% and 0.4%, respectively. Allele G*010107 was absent in both the groups. The frequency of the null allele G*0105N was high (13.8%) in our population as compared to other world populations. Our data support the hypothesis that HLA-G polymorphism may contribute to recurrent foetal loss.     

Occurrence of other reproductive failures among women with recurrent spontaneous abortion

We have previously reported an association between recurrent spontaneous abortion and ectopic pregnancy. We now report that not only ectopic pregnancy, but also other reproductive failures including hydatidiform moles, preterm births, and stillbirths are also associated with recurrent spontaneous abortion. The obstetrical histories of 455 women who had experienced two or more consecutive spontaneous abortions were studied for the occurrence of term births, preterm births, stillbirths, spontaneous abortions, ectopic pregnancies, and hydatidiform moles. The observed frequencies of these reproductive outcomes were compared with the expected frequencies of 920 term births, 80 preterm births, five stillbirths, 150 spontaneous abortions, 14.5 ectopic pregnancies and 0.5 molar pregnancies per 1,000 livebirths. The 455 women had experienced 1,968 pregnancies of which 184 were term births, 30 were preterm births, 16 were stillbirths, 1,669 were spontaneous abortions, 63 were ectopic pregnancies, and six were molar pregnancies. The ratio of observed to expected values was term births 0.1, preterm births 1.6, stillbirths 14.0, spontaneous abortion 6.6, ectopic pregnancy 2.6, and molar pregnancy 7.1. The gravid specific proportions of reproductive outcomes were constant suggesting comorbidity or common cause(s). The commonality that links these types of reproductive failure will provide insight into the mechanisms of reproductive wastage.     

Serological study of parvovirus B19 infection in women with recurrent spontaneous abortions

The feto-pathogenic association of parvovirus B19 (B19) has been sparingly studied in women with abortion, but not in women with recurrent spontaneous abortions (RSA). Serum samples from 116 women with RSA who were pre-screened for S-TORCH, Chlamydia trachomatis infections, anatomical, chromosomal, endocrinal abnormality and Rh incompatibility and those who had no such known causes of abortion were included in the study. Sera were also collected from 136 normal pregnant women and 120 normal non-pregnant women as disease and normal control respectively. All sera were tested at 1:400 dilutions for B19 IgM by in-house ELISA using cloned and baculovirus expressed VP1 and VP2 antigens of B19. The frequency of anti-B19 IgM antibodies in women with RSA was 19.8%, in pregnant females it was 11% and in normal non-pregnant female was 5%. Sera of 23 women with RSA which were positive for B19 IgM tested negative for B19 DNA by PCR. Patients with RSA should be screened for B19 infection and guidelines for treatment should emerge.     

Seroanalysis of Chlamydia trachomatis and S-TORCH agents in women with recurrent spontaneous abortions

Genital tract infections are an important cause of pregnancy loss, many of which are amenable to treatment. There is scarcity of literature on role of S-TORCH agents in recurrent spontaneous abortions (RSA) and available data on role of Chlamydia trachomatis (CT) is controversial. In a retrospective analysis, CT IgM, IgG and IgA antibodies were tested by indirect ELISA in 86, 53 and 30 sera samples respectively from women with RSA (= or > 3 abortions). IgM antibodies using m-capture ELISA for S-TORCH agents (Syphilis, tested by VDRL) were analysed in 47 sera from women with RSA. Results compared with 29 age matched normal pregnant women. Anatomical, endocrine, Rh incompatibility and chromosomal abnormality in the couple were ruled out prior to inclusion in the study. Serum anti-CT IgM positivity was 46.5% in RSA vs. 13.8% in control group (p < 0.001). S-TORCH positivity in RSA group was 31.9% and nil in the control group (p < 0.005). Present study demonstrates a strong association between IgM antibodies to CT and S-TORCH agents in women with history of RSA.     

自然流产患者外周血与蜕膜NK细胞亚群数量变化的研究

目的：研究自然流产患者外周血与蜕膜组织自然杀伤细胞亚群数量的变化。方法：对36例自然流产患者及30例正常健康早孕者（对照）外周血及蜕膜组织中淋巴细胞进行单克隆抗体标记,应用流式细胞仪定性、定量分析技术对NK细胞（natural killer)亚群进行分析。结果：（1）流产组外周血及蜕膜组织NK细胞CD56＋CD16＋百分比较对照组明显升高。（P＜0．01）,而蜕膜组织中NK细胞CD56＋CD16－百分比明显低于对照组（P＜0．001）。（2）外周血与蜕膜组织NK细胞CD56＋CD16＋亚群存在相关性（γ＝0．516,P＜0．05）。结论：NK细胞亚群的数量变化可以引起蜕膜免疫微环境的失调,导致自然流产。外周血与蜕膜NK细胞CD56＋CD16＋亚群存在正相关关系。     

High levels of peripheral blood NK cells in women suffering from recurrent spontaneous abortion are reverted from high-dose intravenous immunoglobulins

PROBLEM: To determine the levels of peripheral blood natural killer (NK) cells in healthy women and recurrent aborters, and the effect of intravenous immunoglobulins (IVIGs) on these levels. METHOD OF STUDY: A total of 659 women were evaluated for NK cells by means of flow cytofluorimetry: 42 non-pregnant healthy women, 394 non-pregnant recurrent spontaneous abortion (RSA) women, 36 pregnant healthy women and 187 pregnant RSA women. Fifty-four of the pregnant RSA women were treated with IVIG; in 18 of them NK cells were measured immediately before and after the very first IVIG infusion (0.5 g/kg body weight). RESULTS: Blood NK cell results were increased in RSA pregnant/non-pregnant women, and significantly reduced by IVIG, even after the very first infusion. In RSA pregnant women treated by means of IVIG therapy, 92.3% success rate was observed. CONCLUSIONS: High levels of NK cells are detected in women affected by RSA. IVIGs are capable of decreasing them with a short- and long-term efficacy, allowing having a very high success rate of pregnancies in RSA women.     

Increased natural killer cell cytotoxicity and IL-2 production in recurrent spontaneous abortion

PROBLEM: To determine whether natural killer (NK) cells cytotoxicity in peripheral blood is altered in patients with a history of recurrent spontaneous abortion (RSA); also, if there is any correlation between cytokine production and NK cytotoxicity. METHOD OF STUDY: In this case-control study, 21 patients with RSA within 24 hr of the last abortion (group I), and 32 pregnants with no history of abortion (group II) were surveyed. NK cell cytotoxicity was evaluated by flow cytometry, and IL-2, IL-10, transforming growth factor beta1 were measured in cell culture supernatant by ELISA method. RESULTS: Group I showed higher NK cytotoxicity than group II at all of effector to target (E:T) ratios (P < or = 0.045).The correlation between production of IL-2 and NK cytotoxicity was positively significant (R = 0.350, P = 0.001). Group I had significantly higher levels of IL-2 than group II (P = 0.001). In group II, the production of IL-10 by peripheral blood mononuclear cells was higher than group I (P = 0.002). CONCLUSION: Increased NK cell cytotoxicity and high level of IL-2 may be considered as a risk factor for RSA.