Clinical trial of immunostimulation with a biological response modifier in unexplained recurrent spontaneous abortion patients

Peripheral blood natural killer cell cytotoxicity in recurrent miscarriage: a systematic review and meta-analysis

Dysregulated natural killer (NK) cells have been associated with recurrent miscarriages (RM). Studies have suggested that high peripheral blood NK cell cytotoxicities (pNKCs) are associated with an increased risk of RM. The aim of this systematic review (SR) and meta-analysis (MAs) is to investigate the difference in pNKC between nonpregnant and pregnant women with RM and controls and determine whether pNKC is reduced by immunotherapy. We searched the PubMed/Medline, Embase, and Web of Science databases. The MAs were conducted to compare pNKCs between women with and without RM before and during pregnancy as well as pre- and post-immunotherapy. Risk of bias in nonrandomized studies was assessed by the Newcastle-Ottawa Scale. Statistical analysis was performed using the Review Manager software. A total of 19 studies were included in the SR and 14 studies in the MAs. The MAs revealed higher pNKCs among nonpregnant women with RM compared to controls (MD, 7.99 95 %CI 6.40-9.58; p < 0.00001). pNKCs were also higher in pregnant women with RM than in pregnant controls (MD, 8.21 95 %CI 6.08-10.34; p < 0.00001). Women with RM showed significantly decreased pNKCs after the immunotherapy compared to before (MD, -8.20 95 %CI -10.20 - -6.19; p < 0, 00001). Additionally, there is an association between high pNKCs and the risk of pregnancy loss in women with RM. However, included studies showed substantial heterogeneities regarding the inclusion criteria of patients, techniques measuring pNKC, and types of immunotherapies. More studies are needed to evaluate the clinical efficiency of pNKCs in managing RM.

Outcomes in prevention and management of miscarriage trials: a systematic review

BACKGROUND

There is a substantial body of research evaluating ways to prevent and manage miscarriage, but all studies do not report on the same outcomes.

OBJECTIVE

To review systematically, outcomes reported in existing miscarriage trials.

SEARCH STRATEGY

MEDLINE, Embase, CINAHL, and Cochrane were searched from inception until January 2017.

SELECTION CRITERIA

Randomised controlled trials (RCTs) reporting prevention or management of miscarriage. Miscarriage was defined as a pregnancy loss in the first trimester.

DATA COLLECTION AND ANALYSIS

Data about the study characteristics, primary, and secondary outcomes were extracted.

MAIN RESULTS

We retrieved 1553 titles and abstracts, from which 208 RCTs were included. For prevention of miscarriage, the most commonly reported primary outcome was live birth and the top four reported outcomes were pregnancy loss/stillbirth (n = 112), gestation of birth (n = 68), birth dimensions (n = 65), and live birth (n = 49). For these four outcomes, 58 specific measures were used for evaluation. For management of miscarriage, the most commonly reported primary outcome was efficacy of treatment. The top four reported outcomes were bleeding (n = 186), efficacy of miscarriage treatment (n = 105), infection (n = 97), and quality of life (n = 90). For these outcomes, 130 specific measures were used for evaluation.

CONCLUSIONS

Our review found considerable variation in the reporting of primary and secondary outcomes along with the measures used to assess them. There is a need for standardised patient-centred clinical outcomes through the development of a core outcome set; the work from this systematic review will form the foundation of the core outcome set for miscarriage.

TWEETABLE ABSTRACT

There is disparity in the reporting of outcomes and the measures used to assess them in miscarriage trials.

NK cell abnormality and its treatment in women with reproductive failures such as recurrent pregnancy loss, implantation failures, preeclampsia, and pelvic endometriosis

The regulation of uterine and peripheral blood natural killer (NK) cells has been associated with problems related to reproductive immunology such as recurrent pregnancy loss (RPL), implantation failure or preeclampsia. NKp46, one of the natural cytotoxicity receptors (NCRs), is a unique marker that functions in NK cell cytotoxicity and cytokine production. Expression of NKp46 on NK cells is lower in women with recurrent pregnancy loss and pregnancy-induced hypertension. Moreover, expression of NKp46 on peritoneal fluid NK cells is lower in women with pelvic endometriosis. Therefore, evaluation of NKp46 on peripheral blood NK cells may provide a means of screening for reproductive abnormalities. Recently, a new type of NK cell, the NK22 cell, has been reported. This cell may be a regulator not only of the mucosal barrier but also of reproduction. For women with RPL showing abnormal uterine and/or peripheral blood NK cells, both intravenous immunoglobulin treatment and intralipid treatment have been reported. The effects of these treatments are still controversial, and further studies are needed in order to clarify their true impact. The present review examines variations in the expression of NCRs on NK cells, the participation of NK22 cells in reproduction, and the possible use of intravenous immunoglobulin or intralipid treatment for women with recurrent pregnancy loss and NK cell abnormality.

Peripheral natural killer cell activity as a predictor of recurrent pregnancy loss: a large cohort study

OBJECTIVE

To determine the predictive value of preconceptional peripheral blood natural killer (pNK) cell activity in patients with recurrent pregnancy loss (RPL).

DESIGN

Cohort study.

SETTING

University department.

PATIENT(S)

A total of 552 patients with a history of two to six consecutive miscarriages.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

The predictive value of preconceptional pNK cell activity for subsequent miscarriage was analyzed using multivariable logistic regression analysis, with age, number of previous miscarriages, and presence/absence of previous live births and bed rest as covariates.

RESULT(S)

Age and number of previous miscarriages, but not high pNK cell activity, were found to be independent risk factors for a subsequent miscarriage. No effect of bed rest and previous live birth on the likelihood of live birth was observed (odds ratios 1.28 [95% confidence interval 0.81-2.02] and 0.91 [0.52-1.59], respectively).

CONCLUSION(S)

Elevated pNK cell activity was found to not be an independent risk factor for subsequent miscarriage. Clinicians should not measure the plasma NK activity as a systematic recurrent pregnancy loss examination, because its clinical significance is yet to be established.

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.

The changes of circulating lymphocyte sub-populations in women with preterm labour: a case-controlled study

OBJECTIVE

The aim of this study was to determine the changes in circulating T-cell subpopulations, B cells and natural killer cells in patients with imminent preterm labour.

METHODS

Thirty-five pregnant patients with imminent preterm labour and 35 women with uncomplicated pregnancies were included in the study. The gestational ages of the patients ranged from 28 to 36 weeks in both groups. The specific lymphocyte antigens were detected using direct staining with monoclonal antibodies, and analysed by flow cytometry.

RESULTS

We observed no significant difference in the mean percentage of T cell subpopulations, natural killer cells and active T cells in the group of patients with preterm labor when compared to controls. The mean percentage of T CD3+ lymphocytes was significantly lower and that of B CD19+ cells higher in the study group when compared to controls.

CONCLUSION

The alterations in maternal circulating lymphocyte subpopulations could be associated with the mechanisms mediating preterm labour.

The role of gamma/delta T cells in the feto-maternal relationship

Polymorphic MHC is absent from the trophoblast, therefore, it resists NK as well as CTL-mediated lysis in vitro. Activated gamma / delta TCR positive cells are significantly enriched in the decidua as well as in peripheral blood of healthy pregnant women. Human peripheral gamma / delta lymphocytes preferentially express the V gamma 9/V delta 2 TCR, whereas those of the decidua use the V delta 1 chain. These subpopulations are functionally polarized, the former being Th1, the latter Th2. Potentially cytotoxic V delta 2+ lymphocytes recognize HLA-E on the trophoblast via the CD94/NKG2A receptor, which induces an inhibitory signal, thus potentially inhibiting Th1 type cytokine production.

Embryonic karyotype of abortuses in relation to the number of previous miscarriages

OBJECTIVE

To examine the frequency of chromosomal abnormalities in products of conception from patients with recurrent miscarriages in relation to the number of previous miscarriages.

DESIGN

Retrospective analysis.

SETTING

Nagoya City University Medical Hospital.

PATIENT(S)

A total of 1,309 women with a history of 2-20 consecutive first-trimester abortions.

INTERVENTION(S)

Chromosomal analysis performed on products of conception with use of a standard G-banding technique.

MAIN OUTCOME MEASURE(S)

The frequencies of abnormal and normal embryonic karyotypes for each number of previous abortions were studied. The subsequent pregnancy outcome of patients whose previous miscarriages were karyotyped were studied along with the predictive value of karyotyping of previous miscarriages for subsequent miscarriages.

RESULT(S)

The miscarriage rate increased with the number of previous spontaneous abortions. The frequency of abnormal embryonic karyotypes significantly decreased and that of normal embryonic karyotypes significantly increased with the number of previous abortions. Among 71 patients whose embryonic karyotypes were normal, 44 aborted subsequently, and 23 of 60 patients whose embryonic karyotypes were abnormal aborted subsequently. Patients with a previous normal embryonic karyotype aborted more frequently than those with an abnormal karyotype.

CONCLUSION(S)

The frequency of normal embryonic karyotypes significantly increases with the number of previous abortions, and a normal karyotype in a previous pregnancy is a predictor of subsequent miscarriage.