High levels of NK cells in the peripheral blood of patients affected with anti-phospholipid syndrome and recurrent spontaneous abortion: a potential new hypothesis

Assessment of the risk of unexplained recurrent spontaneous abortion based on the proportion and correlation of NK cells and T cells in peripheral blood

BACKGROUND

Unexplained recurrent spontaneous abortion (URSA) is difficult to diagnose and treat clinically due to its unknown causeOBJECTIVE: Changes in natural killer (NK) cells, T lymphocytes, and Th1(IFNγ)/Th2(IL-4) cytokines were investigated in the peripheral blood of patients with URSA to examine the pathogenesis, clinical diagnosis, and inform potential treatment strategies for this condition.

METHODS

For this study, we selected patients with URSA as the case group and included normal women in the control group. Flow cytometry was performed to detect lymphocytes and cytokines in the peripheral blood of all subjects.

RESULTS

The proportion of NK cells, Th1 cells, and the Th1/Th2 ratio were significantly higher in the URSA group compared to the control group; whereas the proportion of CD3+T cells was lower. Pairwise correlation analysis revealed a positive correlation between the percentage of NK cells and CD3+T cells, as well as CD3+CD4+T cells. Canonical correlation analysis indicated a significant correlation between NK cells and T cells, including their subgroups.

CONCLUSION

Patients with URSA have immune balance disorders, characterised by an increased proportion of peripheral blood NK cells, Th1, and Th1/Th2 ratio along with a decreased proportion of CD3+T cells. The proportion of NK cells and CD3+T may serve as predictive factors for URSA, while NK cells are closely related to the regulation of CD3+T cells and their subsets. By regulating the level of IFN-γ, NK cells can influence the proportion of CD3+T cells and induce a Th1 (IFNγ)/Th2 (IL-4) imbalance.

Antiphospholipid antibody-mediated NK cell cytotoxicity

Antiphospholipid syndrome (APS) is an autoimmune thrombophilia that is characterised by thrombosis and obstetric complications in the presence of antiphospholipid antibodies (aPL). Pregnancy complications remain a challenging problem for patients with APS, especially during the first trimester. Although natural killer (NK) cells constitute up to 70% of decidual lymphocytes during the first trimester, their contribution to early pregnancy loss in APS is largely unknown. We aimed to analyse whether aPL are able to recruit antibody-dependent cellular cytotoxicity (ADCC) of NK cells, with special emphasis on the differences in the effects of aPL containing anti-β2GPI domain 1 (anti-β2GPI-D1) antibodies (aPL+/D1+) and those that do not (aPL+/D1-). Our findings revealed a differential distribution of NK subsets in the presence of different aPL. Namely, aPL+/D1- IgGs increased CD56^dim/CD16^dim cells, while aPL+/D1 + IgGs increased the number of CD56^bright/CD16^dim cells. ADCC NK cell cytotoxicity was found to be higher in the presence of aPL+/D1- IgGs, as defined by an increased target cell death, degranulation and increased expression of CD11b, CD69 and NKG2D. Overall, our evidence showed that aPL are able to recruit ADCC, suggesting NK cells as candidate cells for APS-related obstetric complications.

Human Leukocyte Antigen (HLA) Typing Study Identifies Maternal DQ2 Susceptibility Alleles among Infertile Women: Potential Associations with Autoimmunity and Micronutrients

BACKGROUND

The interplay between female fertility and autoimmune diseases (AIDs) can involve HLA haplotypes and micronutrients. We analyzed the distribution of HLA-DQ2/-DQ8 in women with infertility or recurrent spontaneous abortion (RSA) and possible associations with AIDs and micronutrient status.

METHODS

Consecutive women (n = 187) with infertility and RSA, and controls (n = 350) were included. All women were genotyped for HLA-DQ2 (DQA1*0201, A1*05, and B1*02) and -DQ8 (DQA1*03 and DQB1*0302) alleles. Serum 25(OH)D, VB12, folate, and ferritin were evaluated.

RESULTS

DQA1*05/B1*02 and the occurrence of at least one DQ2 allele were more prevalent among RSA and infertile women than controls. Infertile women showed lower 25(OH)D and higher prevalence of AIDs than RSA women. In the multivariate analysis, DQA1*05/B1*02 was associated with a significantly higher risk of AIDs in infertile women, and DQA1*05 was independently associated with both 25(OH)D deficiency and AIDs. In RSA women, the presence of AIDs was associated with a significantly higher risk of 25(OH)D deficiency.

CONCLUSION

Our findings showed, for the first time, a higher proportion of DQ2 alleles in infertile and RSA women as compared to controls. Predisposing DQ2 alleles are independent risk factors for AIDs and 25(OH)D deficiency in infertile women and could represent biomarkers for performing early detection of women requiring individually tailored management.

Extensive serum biomarker analysis in the prethrombotic state of recurrent spontaneous abortion

The prethrombotic state (PTS) is a possible cause of recurrent spontaneous abortion (RSA). The aim of this study was to identify serum biomarkers for the detection of RSA with PTS (PSRSA). A Quantibody array 440 was used to screen novel serum‐based biomarkers for PSRSA/NRSA (RSA without PTS). Proteins differentially expressed in PSRSA were analysed using bioinformatics methods and subjected to a customized array and enzyme‐linked immunosorbent assay (ELISA) validation. We used receiver operating characteristic to calculate diagnostic accuracy, and machine learning methods to establish a biomarker model for evaluation of the identified targets. 20 targets were selected for validation using a customized array, and seven targets via ELISA. The decision tree model showed that IL‐24 was the first node and eotaxin‐3 was the second node distinguishing the PSRSA and NRSA groups (an accuracy rate of 100% and an AUC of 1). Epidermal growth factor (EGF) as the node distinguished the PSRSA and NC groups (an accuracy rate of 100% and an AUC of 1). EGF as the node distinguished the NRSA and NC groups (an accuracy rate of 96.5% and an AUC of 0.998). Serum DNAM‐1, BAFF, CNTF, LAG‐3, IL‐24, Eotaxin‐3 and EGF represent a panel of promising diagnostic biomarkers to detect the PSRSA.

Functional NK surrogate biomarkers for inflammatory recurrent pregnancy loss and recurrent implantation failure

PROBLEM

Expansion of circulating NK cells has been related to pregnancy complications. This study aims at investigating several surface NK cell markers to identify a baseline inflammatory profile in women with recurrent pregnancy loss (iRPL) and recurrent implantation failure (iRIF).

METHOD OF STUDY

Expression of NKp30, TIGIT, NKp46, and DNAM-1 on total peripheral blood NK subsets, regulatory (CD56^bright CD16^neg ), and cytotoxic (CD56^dim CD16^pos/neg ) NK cells was measured.

RESULTS

Eighty-three women were recruited and classified into two groups, 58 women with RPL and 25 with RIF. A control group of 31 fertile women was included. Expression of NKp30 on cytNK was significantly higher in RPL (p = .019) and RIF (p < .001) than HC. TIGIT on cytNK cells was also higher in both RPL (p < .001) and RIF (p < .01). An optimal cutoff of 70% for NKp30⁺ cytNK disclosed a sensitivity of 82%, a specificity of 55%, and 83% PPV for RPL diagnosis. A cutoff level of 83% for TIGIT⁺ cytNK was chosen to discriminate between healthy controls and RPL women, with PPV of 84%.

CONCLUSION

Our preliminary data on this RPL and RIF cohorts suggest a simple diagnostic tool by combining NKp30 and TIGIT on cytNK cells to better identify a subgroup of RPL and RIF patients with a baseline inflammatory profile. A more rigorous selection of these patients through phenotyping peripheral cytNK cells may better define patients that could benefit from an immunomodulatory treatment to prevent further pregnancy losses. The performance of these biomarkers requires further investigation and validation in independent cohorts.

Increased Peripheral NKG2A-NKG2D+CD3-CD16+CD56dim NK Cell Subset Was Positively Correlated with Antiphospholipid Antibodies in Patients of Obstetric Antiphospholipid Syndrome

Obstetric antiphospholipid syndrome (OAPS) is an autoimmune disorder with severe life-threatening complications shown during pregnancy. It has been reported that the increase in CD16⁺CD56^dim natural killer (NK) cells in peripheral blood are risk factors for recurrent miscarriages, but this expression of CD16⁺CD56^dim NK cells in OAPS patients has not been reported, and the mechanism is not clearly illustrated. In this study, we compared the distributional profiles of different NK cell subsets and the expressions of NK cell-activating receptors in peripheral blood of patients with OAPS and healthy women. Our results showed significantly increased NKG2A^-NKG2D⁺ subset and decreased NKG2A⁺NKG2D^- subset in CD3^- CD16⁺CD56^dim NK cells, CD3^-CD16^-CD56^bright NK cells and CD56⁺T cells in OAPS patients compared with those in healthy control women. The CD27^-CD11b⁺ subset significantly increased in CD3^-CD16⁺CD56^dim NK cells in OAPS patients compared with those in healthy control women. In addition, the NKG2A^-NKG2D⁺ subset in CD3^-CD16⁺CD56^dim NK subset in triple positivity was higher than single positivity OAPS patients. At the optimal diagnostic threshold established by ROC analysis, using the cut-off of NKG2A^-NKG2D⁺ and CD27^-CD11b⁺ subset in CD3^-CD16⁺CD56^dim NK cells is 10.10% and 92.75%, the sensitivity of NKG2A^-NKG2D⁺ and CD27^-CD11b⁺ to detect patients with OAPS compared with healthy control results was 94.1% and 60.8%, and specificity was 84.2% and 89.5%, respectively, with an area under the curve (AUC) of 0.903 and 0.829, respectively. The NKG2A^-NKG2D⁺ subset in CD3^-CD16⁺CD56^dim NK cells was positively correlated with the antiphospholipid antibodies lg anti-aCL IgG, lg anti-aCL IgM, lg anti-aCL IgA, lg anti-β2GP1 IgM and Complement 4(C4), while the CD27⁺CD11b⁺ subset in CD3^-CD16⁺CD56^dim NK cells was correlated with lg anti-β2GP1 IgG and lg anti-β2GP1 IgA. These results suggested that the NK cytotoxic function enhanced in OAPS patients and unbalanced of NK activating receptors and inhibiting receptors may contribute to the immune pathogenesis of OAPS.

17β-Estradiol Promotes Proinflammatory and Procoagulatory Phenotype of Innate Immune Cells in the Presence of Antiphospholipid Antibodies

Antiphospholipid syndrome (APS) is the most common cause of acquired thrombophilia and recurrent spontaneous miscarriages associated with extended persistence of antiphospholipid antibodies (aPL). How circulating aPL and high-17β-estradiol (E2) environment contribute to the pregnancy complications in APS is poorly defined. Therefore, we aimed to analyse whether E2 could be responsible for the immune cell hyperactivation in aPL- positive (lupus anticoagulant, anti-cardiolipin, anti-β2-glycoprotein) in women. For this, peripheral blood mononuclear cells (PBMCs) from 14 aPL- positive and 13 aPL- negative women were cultured in the presence or absence of E2, LPS or E2+LPS and cell immunophenotype and cytokine release were analysed. In the aPL+ group, E2 presence markedly increased the percentage of NK cells positive for CD69 (p < 0.05), monocytes positive for tissue factor (TF, CD142) (p < 0.05), and B cells expressing PD-L1 (p < 0.05), as well as the elevated production of IL-1β comparing to aPL- women (p < 0.01). Regardless of aPL positivity, E2 augmented the procoagulatory response elicited by LPS in monocytes. Our findings show the ability of E2 to promote proinflammatory and procoagulatory phenotype of innate immune cells in individuals with aPL positivity. Our data highlights the significant impact of female hormones on the activation of immune cells in the presence of aPL.

Anti-domain 1 β2 glycoprotein antibodies increase expression of tissue factor on monocytes and activate NK Cells and CD8+ cells in vitro

Background

β2-Glycoprotein I (β2GPI) represents the major antigenic target for antiphospholipid antibodies (aPL), with domain 1 (D1) being identified as a risk factor for thrombosis and pregnancy complications in APS. We aimed to analyse the ability of aPL, and particularly anti-D1 β2GPI, to stimulate prothrombotic and proinflammatory activity of immune cells in vitro.

Methods

Peripheral blood mononuclear cells (PBMCs) from 11 healthy individuals were incubated with: (1) “anti-D1(+)”—pooled plasma derived from patients suspected of having APS contained anticardiolipin antibodies (aCL), lupus anticoagulant (LA), anti-β2GPI and anti-D1 β2GPI; (2) “anti-D1(−)”—pooled plasma from patients suspected of having APS contained aCL, LA, anti-β2GPI, and negative for anti-D1 β2GPI; (3) “seronegative”—negative for aPL.

Results

The presence of anti-D1(+) and anti-D1(−) plasma resulted in increased HLA-DR and CD11b on monocytes. While only anti-D1(+) plasma markedly increased the percentage and median fluorescence intensity (MFI) of CD142 (tissue factor, TF) on monocytes in comparison with those cultured with anti-D1(−) and seronegative plasma. Anti-D1(+) plasma resulted in increased percentage and MFI of activation marker CD69 on NK and T cytotoxic cells. Expression of IgG receptor FcγRIII(CD16) on monocytes and NK cells was down-regulated by the anti-D1(+) plasma.

Conclusions

Taking together, our study shows the ability of patient-derived aPL to induce immune cell activation and TF expression on monocytes. For the first time, we demonstrated the influence of anti-D1 β2GPI on the activation status of monocytes, NK and cytotoxic T cells. Our findings further support a crucial role of D1 epitope in the promotion of thrombosis and obstetrical complications in APS.

Clinical factors associated with pregnancy outcome in women with recurrent pregnancy loss

The aim of this prospective cohort study was to evaluate clinical factors associated with pregnancy outcomes in women with recurrent pregnancy loss (RPL). Women with a history of two or more pregnancy losses underwent workups for clinical factors of RPL and their pregnancies were followed-up with informed consent. Two hundred eleven (81.5%) of 259 women with RPL became pregnant. The multivariable analyses demonstrated that age (p < .01, OR 0.9, 95%CI 0.97-0.83), uterine abnormality (p < .05, OR 0.3, 95%CI 0.11-0.8), and protein C (PC) deficiency (p < .01, OR 0.14, 95%CI 0.03-0.6) were independent factors for becoming pregnancy in women with RPL. The number of previous pregnancy loss (p < .01, OR 0.57, 95%CI 0.43-0.75) and natural killer (NK) cell activity ≥33% (p < .01, OR 0.31, 95%CI 0.13-0.73) were independent factors for live birth in the subsequent pregnancy. Advanced age, the presence of uterine abnormality, and PC deficiency were risk factors for reduced pregnancy rate in women with RPL. Increased number of previous pregnancy loss and high NK cell activity were risk factors for miscarriage in the subsequent pregnancy. These results involve important information and are helpful for clinical practitioners.

Increased natural killer cell subsets with inhibitory cytokines and inhibitory surface receptors in patients with recurrent miscarriage and decreased or normal subsets in kidney transplant recipients late post-transplant

Patients with recurrent miscarriage (RM) show up-regulated cytotoxic natural killer (NK) cells that are suspected to play a causal role in abortion. In the present study, we investigated counter-regulating inhibitory mechanisms and compared the results in RM patients with those of healthy controls (HC), patients with end-stage renal disease (ESRD) and kidney transplant recipients late post-transplant (TX). NK, NK T and T cell subsets were analysed in the peripheral blood of 31 RM, 14 female ESRD and nine female TX patients as well as 21 female HC using eight-colour fluorescence flow cytometry. Compared with HC, RM patients showed significantly higher absolute numbers of CD56⁺ NK cells co-expressing the phenotype interferon (IFN)-γR⁺ , IL-4⁺ , transforming growth factor (TGF)-β⁺ , IL-4⁺ human leucocyte antigen D-related (HLA-DR)⁺ , TGF-β⁺ HLA-DR⁺ , IL-4⁺ TGF-β⁺ , IL-4⁺ TGF-β^- , IFN-γ⁺ and/or IL-10^- IFN-γ⁺ (all P ≤ 0·01), more IL-17⁺ CD56^bright (P = 0·028) NK cells and more CD56^dim CD16⁺ NK cells co-expressing IFN-γR, IFN-γ, IL-4 and/or TGF-β (all P ≤ 0·01). When the same cell subsets were analysed in ESRD or TX patients, cytokine-producing NK cell subsets were not significantly different from those of HC. RM patients showed significantly higher absolute numbers of CD158a⁺ , CD158b⁺ , CD158a^- CD158e⁺ (all P < 0·05), NKG2D⁺ NKG2A⁺ , NKG2D ⁺ NKG2A^- , NKG2D⁺ and/or NKG2A⁺ (all P ≤ 0·01) CD56⁺ NK cells and higher CD158a⁺ , CD158b⁺ (all P < 0·05), NKG2D⁺ and/or NKG2A⁺ (all P < 0·01) CD56^dim+ CD16⁺ NK cells than HC. In contrast, ESRD patients had normal and TX recipients had lower CD158a⁺ and NKG2D⁺ NKG2A^- CD56⁺ NK cells and lower CD158a⁺ CD56^dim+ CD16⁺ NK cells (all P < 0·05) than HC. RM patients have abnormally high circulating NK cells expressing inhibitory cytokines and inhibitory surface receptors which might contribute to the pathogenesis of RM.

Natural killer cells and T lymphocytes in pregnancy and pre-eclampsia

Although pre-eclampsia (PE), a hypertensive disorder of pregnancy, has significant maternal and fetal morbidity and mortality worldwide, the mechanisms contributing to this disease have not been fully elucidated. Studies in patients and experimental models have shown that changes in the number or function of immune cells of both the adaptive and innate immune systems contribute to the development and pathogenesis of PE. This commentary summarizes our current understanding of the role of the immune system in the pathogenesis of PE, specifically focussing on dysfunction of natural killer (NK) cells and T lymphocyte populations.

Decreased NK cell immunity in kidney transplant recipients late post-transplant and increased NK-cell immunity in patients with recurrent miscarriage

BACKGROUND

There is evidence that NK-cell reactivity might affect graft outcome in transplant recipients and pregnancy in women.

METHOD

NK-cell subsets were determined in whole blood using eight-colour-fluorescence flow cytometry in patients before and after renal transplantation, patients with recurrent miscarriage (RM) and healthy controls (HC).

RESULTS

Patients late post-transplant (late-Tx) with functioning renal transplants showed abnormally low CD56dimCD16+ NK-cells containing both perforin and granzyme (vs HC p = 0.021) whereas RM patients exhibited abnormally high numbers of these cells (vs HC p = 0.043). CD56dimCD16+perforin+granzyme+ NK-cell counts were strikingly different between the two patient groups (p<0.001). In addition, recipients late-Tx showed abnormally low CD8+ NK-cells (vs HC p<0.001) in contrast to RM patients who showed an abnormal increase (vs HC p = 0.008). CD8+ NK-cell counts were strongly different between the two patient groups (p<0.001). Higher perforin+granzyme+CD56dimCD16+ and CD8+ NK-cells were associated with impaired graft function (p = 0.044, p = 0.032). After in-vitro stimulation, CD56dimCD16+ and CD56brightCD16dim/- NK-cells showed strong upregulation of CD107a and IFNy, whereas the content of perforin decreased dramatically as a consequence of perforin release. Recipients late post-Tx showed less in-vitro perforin release (= less cytotoxicity) than HC (p = 0.037) and lower perforin release was associated with good graft function (r = 0.738, p = 0.037). Notably, we observed strong in-vitro perforin release in 2 of 6 investigated RM patients. When circulating IL10+CD56bright NK-cells were analyzed, female recipients late post-Tx (n = 9) showed significantly higher relative and absolute cell numbers than RM patients (p = 0.002 and p = 0.018, respectively); and high relative and absolute IL10+CD56bright NK-cell numbers in transplant recipients were associated with low serum creatinine (p = 0.004 and p = 0.012) and high glomerular filtration rate (p = 0.011 and p = 0.002, respectively). Female recipients late post-Tx exhibited similar absolute but higher relative numbers of IL10+IFNy- NK-cells than RM patients (p>0.05 and p = 0.016, respectively).

CONCLUSION

NK-cells with lower cytotoxicity and immunoregulatory function might contribute to good long-term graft outcome, whereas circulating NK-cells with normal or even increased cytotoxicity and less immunoregulatory capacity are observed in patients with RM.

Immunologic Abnormalities, Treatments, and Recurrent Pregnancy Loss: What Is Real and What Is Not?

Recurrent pregnancy loss, depending on the definition, affects 1% to 3% of women aiming to have a child. Little is known about the direct causes of recurrent pregnancy loss, and the condition is considered to have a multifactorial and complex pathogenesis. The aim of this review was to summarize the evaluation and the management of the condition with specific emphasis on immunologic biomarkers identified as risk factors as well as current immunologic treatment options. The review also highlights and discusses areas in need of further research.

Uterine CD56dim and CD16+ Cells in Refractory Antiphospholipid Antibody-Related Pregnancy Loss and Chromosomally Intact Abortuses: A Case-Control Study

AIM

To evaluate the role of uterine natural killer (uNK) CD56^dim and CD16⁺ cells in patients with refractory antiphospholipid, antibody-mediated, recurrent, pregnancy loss.

SETTINGS AND DESIGN

A case-control study was conducted between 2012 and 2015 at a university hospital.

PATIENTS AND METHODS

A group of 118 women with a history of antiphospholipid antibody syndrome experiencing fetal loss in spite of low dose aspirin (LDA) and low molecular weight heparin (LMWH) treatment in the current pregnancy were included in this study. A group of 32 patients undergoing an elective termination of viable pregnancies before 20 weeks were taken as controls. Suction evacuation was performed to collect abortus specimens, and uterine wall curettage was performed to collect decidua specimens, which were then stained using monoclonal antibodies specific to CD56 and CD16.

STATISTICS

Statistical analyses were performed using the Statistical Package for the Social Sciences version 18 software. Chi-square and Fisher exact tests were used for making comparison between the groups.

RESULTS

Abnormal fetal karyotype was found in nine (9/97) cases of the study group, which means that abnormal karyotype accounts for only 9.3% of the causes of failure of treatment. Abnormal karyotype was found in four cases of the control group. Only cases with normal karyotyping were subjected to decidual uNK cells analysis. We found that CD56^dim and CD16⁺ were found in the decidua of 79 cases (79/97), which means that aberrant natural killer cells expression might account for 81.4% of the cases of refractory antiphospholipid antibody (APA)-mediated recurrent pregnancy loss.

CONCLUSION

CD56^dim and CD16⁺ uNK cells might be correlated with refractory APA-mediated recurrent pregnancy loss.

Intravenous immunoglobulin G in women with reproductive failure: The Korean Society for Reproductive Immunology practice guidelines

The task force of the Korean Society for Reproductive Immunology recommends intravenous immunoglobulin G treatment in women with reproductive failure, including recurrent pregnancy loss and/or repeated implantation failure, who show cellular immune factors such as abnormal natural killer cell levels, natural killer cell cytotoxicity, and/or type 1 T helper immunity.

Innate Immune System at the Maternal-Fetal Interface: Mechanisms of Disease and Targets of Therapy in Pregnancy Syndromes

The maternal-fetal interface is an immunologically unique site that allows the tolerance to the allogenic fetus and maintains host defense against possible pathogens. Balanced immune responses are required for the maintenance of successful pregnancy. It has been demonstrated that innate immune disturbances may be responsible for some adverse pregnancy outcomes such as preeclampsia (PE); hemolysis, elevated liver enzymes, low platelets (HELLP) syndrome; intrauterine growth restriction (IUGR); and recurrent spontaneous abortion (RSA). Observational studies suggest that immunomodulatory treatments in pregnancy-specific complications may improve both the hematological/biochemical features in the mother and the perinatal outcomes. The following review will discuss how recent and relevant findings in the field of the innate immunity have advanced our understanding of the role of inflammation and innate immune system in the pathogenesis of pregnancy failure and will discuss the therapeutic outcomes of the existing studies and clinical trials in light of these new insights.

Peripheral blood natural killer cells and mild thyroid abnormalities in women with reproductive failure

Abnormalities in peripheral blood natural killer (NK) cells have been reported in women with primary infertility and recurrent spontaneous abortion (RSA) and several studies have been presented to define cutoff values for abnormal peripheral blood NK cell levels in this context. Elevated levels of NK cells were observed in infertile/RSA women in the presence of thyroid autoimmunity (TAI), while no studies have been carried out, to date, on NK cells in infertile/RSA women with non-autoimmune thyroid diseases. The contribution of this study is two-fold: (1) the evaluation of peripheral blood NK cell levels in a cohort of infertile/RSA women, in order to confirm related data from the literature; and (2) the assessment of NK cell levels in the presence of both TAI and subclinical hypothyroidism (SCH) in order to explore the possibility that the association between NK cells and thyroid function is not only restricted to TAI but also to SCH. In a retrospective study, 259 age-matched women (primary infertility [n = 49], primary RSA [n = 145], and secondary RSA [n = 65]) were evaluated for CD56+CD16+NK cells by flow cytometry. Women were stratified according to thyroid status: TAI, SCH, and without thyroid diseases (ET). Fertile women (n = 45) were used as controls. Infertile/RSA women showed higher mean NK cell levels than controls. The cutoff value determining the abnormal NK cell levels resulted ⩾15% in all the groups of women. Among the infertile/RSA women, SCH resulted the most frequently associated thyroid disorder while no difference resulted in the prevalence of TAI and ET women between patients and controls. A higher prevalence of women with NK cell levels ⩾15% was observed in infertile/RSA women with SCH when compared to TAI/ET women. According to our data, NK cell assessment could be used as a diagnostic tool in women with reproductive failure and we suggest that the possible association between NK cell levels and thyroid function can be described not only in the presence of TAI but also in the presence of non-autoimmune thyroid disorders.

Delineating the deranged immune system in the antiphospholipid syndrome

The antiphospholipid syndrome (APS) is a systemic autoimmune disease that is characterized serologically by the presence of antiphospholipid antibodies (aPL) and clinically by vascular thrombosis and obstetric complications. The protein β2 glycoprotein I (β2GPI) is identified as the most important autoantigen in this syndrome. Activation of endothelial cells, thrombocytes and placental tissue by anti-β2GPI antibodies relates to the clinical manifestations of APS. This review describes genetic and environmental factors in relation to APS and summarizes the current knowledge on abnormalities in components of both the innate and adaptive immune system in APS. The role of dendritic cells, T-cells, B-cells, monocytes, neutrophils and NK-cells as well as the complement system in APS are discussed. Several gaps in our knowledge on the pathophysiology of APS are identified and a plea is made for future extensive immune cell profiling by a systems medicine approach in order to better unravel the pathogenesis of APS, to gain more insight in the role of the immune system in APS as well as having the potential to reveal biomarkers or novel therapeutic targets.

Prolactin and natural killer cells: evaluating the neuroendocrine-immune axis in women with primary infertility and recurrent spontaneous abortion

PROBLEM

An association between serum prolactin (PRL) and peripheral blood natural killer (NK) cells has been described in healthy women. We explored for the first time the PRL response to the thyrotrophin-releasing hormone (TRH) test and the association between PRL and NK cells in women with reproductive failure.

METHODS

A total of 130 women [31 primary infertility, 69 recurrent spontaneous abortion (RSA), and 30 fertile women] were evaluated by a TRH test to analyze the following: basal PRL (bPRL), peak-time PRL, PRL absolute and relative increase, decline-time PRL. Hyperprolactinaemia (HPRL) was defined as bPRL ≥15 ng/mL. NK cells were characterized by immunophenotyping.

RESULTS

Significantly higher bPRL levels were found in the infertile women than in controls. Both the infertile and the RSA women showed significantly elevated NK levels. bPRL levels correlated with NK cells in HPRL-infertile women.

CONCLUSIONS

In patients with HPRL, an association between NK cell and bPRL results. The dynamic test in the infertile women would help in the management of the pregnancy impairment.

Resistance of uterine radial artery blood flow was correlated with peripheral blood NK cell fraction and improved with low molecular weight heparin therapy in women with unexplained recurrent pregnancy loss

PROBLEM

To investigate whether peripheral blood natural killer (pbNK) cell levels are associated with uterine blood flow, and low molecular weight heparin (LMWH) treatment is effective to improve uterine blood flow in women with decreased uterine blood flow and unexplained recurrent pregnancy loss (RPL).

METHOD OF STUDY

This was a prospective controlled study. Study population included 33 pregnant women (between 5 and 7 weeks gestation) with ≥ 2 RPL and controls were 47 healthy pregnant women. pbNK cell fractions (CD3(-)/56(+)/16(+)) of peripheral blood mononuclear cells were measured by flow cytometry. Uterine color-pulsed Doppler ultrasound was performed to evaluate uterine radial artery resistance index (URa-RI). In RPL women with elevated URa-RI (≥ 0.5), LMWH (ranges 40-60 mg/day) was administered subcutaneously daily and URa-RI was reassessed 1 week later. Pregnancy outcome was analyzed at 12 weeks gestation.

RESULTS

URa-RI was significantly higher in pregnant women with RPL than controls (0.60 ± 0.14 versus 0.54 ± 0.12, P = 0.039). In pregnant women with RPL, pbNK cell fractions displayed a positive correlation with URa-RI (Pearson's r = 0.429, P = 0.013). URa-RI was significantly decreased 1 week after LMWH treatment as compared to that of pretreatment (pretreatment RI: 0.65 ± 0.11 versus post-treatment RI: 0.56 ± 0.13, P = 0.011). Pregnancy outcome of RPL women with LMWH treatment was not different from that of pregnant controls (73.3% versus 85.0%, P = NS).

CONCLUSION

Increased pbNK cells are associated with decreased uterine radial artery blood flow. LMWH treatment effectively decreases URa-RI with improved pregnancy outcome in women with RPLs and elevated URa-RI. A larger scale study is needed to verify these findings.

Determination of clinical cellular immune markers in women with recurrent pregnancy loss

PROBLEM

Dysregulated natural killer (NK) immunity and T-cell immunity are associated with recurrent pregnancy loss (RPL). We aim to define clinically relevant NK and T-cell parameters for RPL and determine their cutoff values.

METHODS OF STUDY

Ninety-five women with RPL (>3) including 42 idiopathic and 53 known-etiology RPL, and 29 age-matched fertile controls were enrolled. Peripheral blood immunophenotype, NK cell cytotoxicity (NKC), and T-helper (Th) 1 and Th2 cytokine producing cell ratios (Th1/Th2) were measured using flowcytometry. The cutoff values were determined using Youden's J with likelihood ratio (LR) >2.

RESULTS

Natural killer cell percentage and NKC, TNF-α(+) Th1 cells, and TNF-α/IL-10 producing Th1/Th2 cell ratio were significantly higher in idiopathic RPL than controls. By the area under the curve (AUC) analysis, NK cell percentage (AUC = 0.691), NKC (AUC = 0.649), TNF-α(+) Th1 cells (AUC = 0.681) and Th1/Th2 cell ratio (AUC = 0.660) were highly specific for RPL. The cutoff values for NK cell percentage, NKC (E:T cell ratio 25:1), and TNF-α/IL-10 producing Th1/Th2 cell ratio are 16.1, 23.8, and 36.2%, respectively. Seventy-six percent of idiopathic RPL showed at least one of more immune abnormalities by these criteria.

CONCLUSION

Differences in NK cell percentages, NKC and Th1/Th2 cell ratio differentiated RPL from fertile controls.

New decision-tree model for defining the risk of reproductive failure

PROBLEM

Natural killer (NK) cells play a key role in embryo implantation and pregnancy success, whereas blood and uterine NK expansions have been involved in the pathophysiology of reproductive failure (RF). Our main goal was to design in a large observational study a tree-model decision for interpretation of risk factors for RF.

METHODS OF STUDY

A hierarchical multivariate decision model based on a classification and regression tree was developed. NK and NKT-like cell subsets were analyzed by flow cytometry.

RESULTS

By multivariate analysis, blood NK cells expansion was an independent risk factor for RF (both recurrent miscarriages and implantation failures). We propose a new decision-tree model for the risk interpretation of women with RF based on a combination of main risk factors.

CONCLUSIONS

Women with age above 35 years and >13% CD56⁺CD16⁺ NK cells showed the highest risk of further pregnancy loss (100%).

Treatment of refractory obstetric antiphospholipid syndrome: the state of the art and new trends in the therapeutic management

Objective

To date, there are no reliable data regarding the actual treatment received by women with refractory obstetric antiphospholipid syndrome (OAPS). The aim of this study was to assess current clinical evidence and new trends in the treatment of refractory OAPS.

Methods

A non-systematic but comprehensive literature search using relevant keywords was made to identify relevant articles published in English from different computerized databases: PubMed (Medline), Google Scholar electronic database search and The Cochrane Library, from January 2000 to March 2012. Studies on the treatment of poor obstetric outcomes in women with OAPS were included. Prospective randomized clinical trials, cohort studies, reviews, systematic reviews and meta-analysis were retrieved.

Results

A total of 130 articles were finally selected for this review, including 17 randomized clinical trials and four meta-analyses. The majority of articles were non-randomized original papers and basic and clinical reviews.

Conclusion

Up to 20% of women with OAPS do not receive the currently recommended therapeutic regimen. Unfortunately, well-designed studies regarding the usefulness of new drugs in refractory OAPS are scarce. Hydroxychloroquine and low-dose prednisolone appear to be useful when added to standard therapy. Current data do not support the use of intravenous immunoglobulins in this field. The role played by double anti-aggregant therapy, fondaparinux, vitamin D, pentoxifylline and TNF-targeted therapies should be tested in well-designed studies.

The correlation of autoantibodies and uNK cells in women with reproductive failure

There is conflicting evidence on the role of autoimmune disorders in reproductive failure, including recurrent miscarriage (RM) and recurrent implantation failure (RIF), after in vitro fertilisation (IVF). Several commonly studied autoimmune markers in women with reproductive failure include antiphospholipid antibodies (APAs), thyroid peroxidase antibodies (TPA) and uterine natural killer (uNK) cells. However, there have not been any studies that have examined the correlation of these markers in women with reproductive failure. To determine if women who tested positive for autoantibodies (APA and thyroid peroxidase antibodies) have significantly higher uNK cell numbers than women who tested negative for these antibodies, the percentage of stromal cells that stained positive for CD56 was identified by immunocytochemistry in endometrial biopsies from 42 women with unexplained RM (29 women tested negative for autoantibodies and 13 women tested positive for autoantibodies) and 40 women with unexplained RIF (30 women tested negative for autoantibodies and 10 women tested positive for autoantibodies). Biopsies were obtained on days LH+7 to LH+9. There was no significant difference in uNK cell numbers between women with unexplained RM who tested negative and those who tested positive for autoantibodies. Similarly, there was no significant difference in uNK cell numbers between women with unexplained RIF who tested negative and those who tested positive for autoantibodies. In women with reproductive failure the presence of autoantibodies does not appear to affect the numbers of uNK cells in the endometrium around the time of implantation.

Intravenous immunoglobulin treatment increased live birth rate in a Spanish cohort of women with recurrent reproductive failure and expanded CD56(+) cells

PROBLEM

Natural killer (NK, CD3(-)CD56(+)/CD16(+)) and NKT-like cells (CD3(+)CD56(+)/CD16(+)) activity is considered among the key factors for reproductive success. In the absence of immunological screening, beneficial effects of intravenous immunoglobulin (IVIG) in preventing recurrent reproductive failure (RRF) have not been reported. Here, we analyse the IVIG influence on pregnancy success in women with RRF and circulating NK or/and NKT-like cells expansion.

METHOD OF STUDY

One hundred fifty-seven women with previous recurrent miscarriage and/or recurrent implantation failure after in vitro fertilization were consecutively studied. Sixty-four patients with CD56(+) cell expansion, no apparent underlying disease and who maintained their desire to conceive were selected. Forty of them received IVIG during pregnancy.

RESULTS

Overall, the clinical pregnancy rate for the women under IVIG therapy was 92.5% and the live birth rate was 82.5%. Significantly lower pregnancy and live birth rates (25% and 12.5%, respectively) were observed for the patients with recurrent pregnancy loss and NK/NKT-like cells expansion without IVIG. After three cycles of IVIG, NK cell percentages decreased significantly and these values persisted throughout gestation.

CONCLUSION

Intravenous immunoglobulin therapy for women with RRF and NK or NKT-like cell expansion was a safe and beneficial therapeutic strategy that associated with high clinical pregnancy and live birth rates.

Quantitative and functional changes in peripheral natural killer cells in women with reproductive failure after artificial insemination with donor sperm

Considerable evidence indicates that quantitative and/or functional abnormalities of natural killer (NK) cells are associated with reproductive failure. The objective of this study was to determine if peripheral NK percentage and activity are altered in women with reproductive failure after artificial insemination by donor (AID), and which parameters can best discriminate women with AID failure and normal controls. A case-control study of 20 fertile controls, 25 patients undergoing more than four treatment cycles without success (Group I), 25 experiencing biochemical pregnancy loss (Group II), and 25 undergoing embryo growth arrest or miscarriage (Group III) was performed. The peripheral NK percentage and cytotoxicity was evaluated by flow cytometry. Our results showed that a significantly increased percentage of NK cell cytotoxicity (NKCC) was detected in all study groups compared with the controls. The percentage of CD56(+) NK cells was elevated in Groups II and III compared with the controls. The percentage of CD56(+)CD16(+) NK cells in the study groups was higher than that in the controls. By using receiver operating characteristic curve and logistic regression analysis, we found that NKCC combined with CD56(+)CD16(+) NK percentage had good predictive power. The overall predicted percentage correct was 0.89. These results suggest that enhanced NKCC and an elevated cytotoxic NK percentage may be associated with AID failure and can be biomarkers for predicting AID-induced failure.

Pathophysiological mechanisms in antiphospholipid syndrome

Antiphospholipid syndrome is a systemic autoimmune disease associated with thrombosis and recurrent fetal loss in the setting of detectable antiphospholipid (aPL) antibodies. The major antigenic target has been identifed as β₂-glycoprotein I (β₂GPI), which mediates binding of aPL antibodies to target cells including endothelial cells, monocytes, platelets and trophoblasts, leading to prothrombotic and proinfammatory changes that ultimately result in thrombosis and fetal loss. This article summarizes recent insights into the role of β₂GPI in normal hemostasis, interactions between aPL antibodies, β₂GPI and cell-surface molecules, molecular prothrombotic and proinfammatory changes induced by aPL antibodies and pathogenic changes leading to fetal loss in antiphospholipid syndrome. New directions in therapy using these insights are examined.

NK cells, autoantibodies, and immunologic infertility: a complex interplay

Infertility and recurrent spontaneous abortion (RSA) are heterogeneous conditions that have been frequently explained with an immunological pathomechanism. A deeper insight into apparently unexplained infertility and RSA shows increasing evidences supporting both alloimmune and autoimmune mechanisms, in which natural killer (NK) cells and autoantibodies seem to play a relevant role. Successful pregnancy is considered as Th1-Th2 cooperation phenomenon, with a predominantly Th2-type lymphocytes response, together with the emerging role of interleukin (IL)-12, IL-15, and IL-18 and of other unidentified soluble factors dependent on NK cells. Uterine NK cells comprise the largest population at implantation site, and their activity, characteristics, and abundance suggest that they participate at the "decidualization" process that, vice versa, induces NK activation and recruitment in each menstrual cycle. However, NK cell alteration may be associated with impaired pregnancy, and the modulation in the number of circulating NK cells is most likely to be a primary event rather than an active inflammation/drug administration consequence during an inflammatory/autoimmune process, thus playing an important role in the pathogenesis of immunological infertility. Relationships within immunological infertility, recurrent spontaneous abortion, autoantibodies, and NK cells will be reviewed herein.

Quantitative abnormalities of peripheral blood distinct T, B, and natural killer cell subsets and clinical findings in obstetric antiphospholipid syndrome

OBJECTIVE

Few studies have assessed immunophenotypic abnormalities on lymphocyte subsets in patients with antiphospholipid syndrome (APS). We performed an extended immunological study to define alterations of distinct T, B, and natural killer (NK) cell subsets in obstetric patients with APS and their relationship with APS-associated complications.

METHODS

PATIENTS AND CONTROLS

36 women with APS [Sydney criteria, Group A1 without thrombosis (n=26), Group A2 with thrombosis (n=10)]; and 36 age matched women with recurrent abortion without antiphospholipid antibodies (disease controls; Group B), 36 healthy parous women (healthy controls; Group C), and 36 healthy nonparous women (healthy controls; Group D). Thrombotic events occurred after history of abortions in all A2 women. Three-color whole-blood flow cytometry was used to characterize the distinct immunophenotypes.

RESULTS

A1 patients had significantly higher percentages of CD4+CD45RA-CCR7+ central memory cells (A1 vs D), higher percentages of activated CD4+CD25+ T cells (A1 vs D), and lower percentages and absolute counts of CD4+CD45RA-CCR7- effector memory cells (A1 vs D). Group A2 patients had higher percentages and absolute numbers of CD19+CD27-IgD+ naive B cells (A2 vs A1 vs all controls), lower percentages and absolute numbers of CD3-CD56+CD16+ NK cells (A2 vs all controls), and higher percentages of activated CD4+DR+ (A2 vs all controls), CD8+DR+ (A2 vs A1 vs C vs D), CD4+CD38+DR+ (A2 vs D), and CD4+CD25+DR+ T cells (A2 vs all controls). Increased percentages of CD8+DR+ T cells [relative risk (RR) 2.43, 95% CI 1.09-5.44, p=0.02] and of naive B cells (RR 3.05, 95% CI 1.30-7.11, p=0.009) were associated with development of thrombosis.

CONCLUSION

In obstetric patients with APS we documented significant changes in T, B, and NK cell homeostasis. Increased levels of CD8+DR+ and CD19+CD27-IgD+ cells might identify obstetric patients with APS at risk of having thrombosis.

Clinical implication of natural killer cells and reproduction

The regulation of natural killer (NK) cells in the peripheral blood and endometrial layers has been associated with reproductive immunopathology such as recurrent spontaneous abortions (RSA), infertility of implantation failures, or pre-eclampsia. The placenta has a complex anatomical structure and different subsets of NK cells with various functional roles can directly interact with trophoblasts. NK cell subpopulations and their functions, putative roles of NK cells in peripheral blood and endometrium are reviewed in relation to RSA and infertility. An increase in NK cell numbers and /or activity in pre- or post-conceptional period in women with RSA or infertility with multiple implantation failures are a significant clinical concern. In addition, immuno-phenotypic characteristics of NK cells in these women support the changes for their increased activity status. Further studies are needed to explore underlying mechanism of NK cells in RSA, infertility, and other reproductive immunopathologies. Possible neurological and hormonal control of NK cells and NK cell interaction with various leukocyte populations need further investigation in women with reproductive failures.

NK cells in autoimmunity: a two-edg'd weapon of the immune system

Natural killer (NK) cells are part of the innate-immune system and respond rapidly to a variety of insults via cytokine secretion and cytolytic activity. Their main function is first line of innate immunity across viral, bacterial and parasitic infections. NK-cells are not solely killers but can also act as regulators of adaptive immunity. It is evident from literature that NK-cells are deeply involved in autoimmunity, but the question is how and why they act as a two edged weapon. Number of circulating NK-cells can be frequently altered depending on the disease taken into consideration. Cytokine milieu, the microenvironment in which they mature and other stimuli acting on different cell surface receptors may differently trigger NK-cells response and influence their role in autoimmune diseases. Functional differences between NK-cells at different anatomical sites, the adaptability of NK-cells effector responses and genetic factors may also explain differences in such responses. Thus, NK-cell alterations may be associated with increased autoimmunity and the modulation in the number of circulating NK-cells seems to be a primary event rather than an active inflammation/drug administration consequence during inflammatory/autoimmune processes, playing a fundamental role in the pathogenesis of a number of autoimmune diseases.