Detailed analysis of peripheral blood natural killer cells in women with repeated IVF failure

Exploring the Immunological Aspects and Treatments of Recurrent Pregnancy Loss and Recurrent Implantation Failure

Recurrent pregnancy loss (RPL) is defined as the occurrence of two or more consecutive pregnancy losses before 24 weeks of gestation. It affects 3-5% of women who are attempting to conceive. RPL can stem from a variety of causes and is frequently associated with psychological distress and a diminished quality of life. By contrast, recurrent implantation failure (RIF) refers to the inability to achieve a successful pregnancy after three or more high-quality embryo transfers or at least two instances of egg donation. RIF shares several causative factors with RPL. The immunological underpinnings of these conditions involve alterations in uterine NK cells, reductions in M2 macrophages and myeloid-derived suppressor cells, an increased Th1/Th2 ratio, a decreased Treg/Th17 ratio, the presence of shared ≥3 HLA alleles between partners, and autoimmune disorders. Various therapeutic approaches have been employed to address these immunological concerns, achieving varying degrees of success, although some therapies remain contentious within the medical community. This review intends to explore the immunological factors implicated in RPL and RIF and to analyze the immunological treatments employed for these conditions, which may include steroids, intravenous immunoglobulins, calcineurin inhibitors, anti-TNF antibodies, intralipid infusions, granulocyte colony-stimulating factor, and lymphocyte immunotherapy.

Ovarian Stimulation Effects on Ghrelin Secretion and Reproductive Potential

OBJECTIVE

Finely regulated Ghrelin (Ghrl) secretion is essential during early pregnancy, as infra or supraphysiologic levels can be detrimental. Since oestrogens stimulate Ghrl synthesis, ovarian stimulation (OS) might increase ghrelinemia, thus being detrimental for fertility. The aim of this work was to evaluate whether OS increases ghrelinemia and associates with maternal endocrine and immune biomarkers and reproductive success.

DESIGN

The 97 women undergoing assisted reproduction were grouped as follows: OS: undergoing OS and fresh embryo transfer (n = 35); FET: undergoing frozen embryo transfer in a cycle different from that of OS (n = 25) and, OD: undergoing embryo transfer in oocyte donation cycles (n = 37). At embryo transfer day, several endocrine and immune biomarkers were assessed.

RESULTS

OS patients showed significantly higher serum estradiol, progesterone and Ghrl, than those not stimulated. Patients that suffered miscarriage showed significantly lower concentrations of sex-hormones, with a similar trend for Ghrl, that deserves further investigation. Moreover, OS patients showed decreased frequencies of circulating T cells and reduced ratios of uNK/NK cells, which significantly associated with serum levels of sex-hormones. Besides, ROC curves identified cut-off values predictive of clinical pregnancy and/or miscarriage for peripheral counts of uNK cells, T cells, and uNK/NK cells ratio.

CONCLUSIONS

As hypothesised, OS significantly increased serum Ghrl in correlation with sex-hormone levels. These last, significantly associated with maternal immune response and reproductive outcome. Although Ghrl exhibited a similar profile, it did not reach statistical significance, indicating the need for further investigation. Additionally, the identification of maternal immunological cut-off values holds significant clinical relevance.

The role of probiotics in restoring the Th1 to Th2 ratio in women experiencing recurrent implantation failure; a double-blind randomized clinical trial

BACKGROUND

Among the complex causes of infertility, Recurrent Implantation Failure (RIF) stands out as a challenging condition. Immunological aberrations are closely implicated in RIF, particularly the imbalance between T helper 1 (Th1) and T helper 2 (Th2) cytokines. Interest in harnessing probiotics to enhance fertility outcomes in RIF-affected women is growing. This study aimed to investigate the potential of probiotics in restoring the Th1 to Th2 ratio and enhancing implantation outcomes in women experiencing RIF.

METHODS

A double-blinded randomized controlled trial enrolled 50 women with a record of at least three RIFs and 50 women with successful pregnancies as a control group in our study. RIF patients were randomly assigned to either the probiotic intervention group (n = 25) or the placebo group (n = 25). The probiotic group administered two tablets per day for 6 months the probiotic tablets that contained prebiotic. At the same time, the placebo group received an identical-looking placebo. Flow cytometry technique was used to evaluate Th1 and Th2 cell frequencies. Gene expression of IL-4, IL-10, TNF-α and IFN-ɣ was analyzed using QRT-PCR. Serum concentrations of IL-4, IL-10, TNF-α and IFN-ɣ cytokines were evaluated using the ELISA technique.

RESULTS

Flow cytometry analysis revealed significantly higher Th1 cell percentages in RIF patients compared to healthy controls, while healthy controls exhibited more significant Th2 cell proportions. Probiotic intervention led to a reduction in Th1 cells and an increase in Th2 cells in RIF patients. ELISA analysis indicated higher proinflammatory and lower anti-inflammatory cytokines compared to controls. After probiotic treatment, TNF-α and IFN-ɣ levels decreased, while IL-10 and IL-4 levels increased in RIF patients. QRT-PCR analysis showed no significant differences in cytokine gene expression between RIF patients before intervention. After probiotic therapy, pro-inflammatory cytokine expression decreased, and anti-inflammatory cytokine expression increased. Placebo treatment resulted in limited changes. Probiotic intervention effectively modulated the Th1 to Th2 ratio in RIF patients, evidenced by reduced Th1 cell percentages, enhanced Th2 cell populations, and cytokine level adjustments. The probiotic intervention improved implantation outcomes in women with RIF, as evidenced by a higher clinical pregnancy rate in the treatment group compared to the placebo group (p = 0.037).

CONCLUSION

These findings highlight the potential of probiotics in restoring immune balance and improving implantation outcomes in women with RIF.

Endometrial scratching and intralipid treatment-no general recommendations

Objectives

Endometrial scratching (ES) and/or intravenous intralipid therapy (in cases of increased uterine natural killer cells, uNKs) are still conducted in several fertility centers as "add-on" treatments in patients undergoing ART, although convincing evidence for beneficial effects is lacking.

Study design

In this retrospective study, associations between ES treatment or additional intralipid therapy and pregnancy and live birth rates of 1,546 patients undergoing 2,821 IVF-/ICSI-treatment cycles with fresh or frozen embryo transfers in a German fertility-center between 1st January 2014 and 31th May 2017 were analyzed.

Results

Overall pregnancy and live birth rates for all 2,821 treatment cycles (468 cycles with ES) were 32.8% and 23.5%. There were no statistically significant differences in pregnancy or live birth rates between first treatment cycles with and without ES (p = 0.915 and p = 0.577) or between second cycles following an unsuccessful first cycle with and without ES (p = 0.752 and p = 0.623). These results were confirmed using multivariable generalized estimating equations (GEE) models accounting for non-independency of multiple treatment cycles per patients that included all cycles and showed no significant effect of ES on pregnancy (p = 0.449) or live birth rates (p = 0.976). Likewise, a GEE model revealed no significant effect of intralipid treatment on pregnancy (p = 0.926) and live birth rates (p = 0.727).

Conclusions

Our results reveal no evidence that ES increases the pregnancy or live birth rates in women undergoing their first or further IVF cycle with fresh or frozen embryo transfer. Intralipid treatment was also not beneficial. Even if patients explicitly ask for it, these procedures are not recommended outside of clinical studies.

The use of immunomodulation therapy in women with recurrent implantation failure undergoing assisted conception: A multicentre cohort study

PROBLEM

Recurrent implantation failure (RIF) after multiple embryo transfers remains a vexing problem and immunomodulators have been used with conflicting results. This study aims to assess the effect of immunomodulation therapy on live birth rate (LBR) in women with RIF undergoing assisted reproduction treatment (ART).

METHOD OF STUDY DESIGN

This is a retrospective cohort study in multicentre network of private assisted conception units in the UK. The study included women who had at least two failed attempts of embryo transfers at CARE fertility network in the period from 1997 to 2018. Women in the treatment group had immunomodulator drugs in the form of corticosteroids, low molecular weight heparin (LMWH), and intravenous intralipid (IVIL) infusions, either separately or in combination, after immunological testing, in addition to standard ART whilst women in the control group had only ART without immunomodulators. The primary outcome was LBR per cycle. Secondary outcomes included the rates of clinical pregnancy (CPR), cumulative live birth (CLBR), and miscarriage.

RESULTS

A total of 27 163 ART cycles fulfilled the inclusion criteria, of which 5083 had immunomodulation treatment in addition to standard ART treatment, and 22 080 had standard ART treatment alone. Women in the treatment group were significantly older (mean age 38.5 vs. 37.1 years, p < .001), and had a higher number of previous failed ART cycles (mean 4.3 vs. 3.8, p < .01). There was a higher LBR in women who received immunomodulation therapy when compared with the control group (20.9% vs. 15.8%, odds ratio [OR] 1.4, 95% confidence interval [CI] 1.29-1.53, p < .001). Multivariate regression analysis showed that immunomodulation treatment was a significant independent predictor of live birth after adjusting for other confounders (adjusted OR [aOR] 1.33, 95% CI 1.15-1.54, p < .001). Survival analysis showed a higher CLBR in the treatment group (adjusted hazard ratio [aHR] 1.78, 95% CI 1.62-1.94, p < .001).

CONCLUSION(S)

This study provides evidence of a potential beneficial effect of immunomodulation therapy in women with RIF after immunological testing. There remains a need for high quality, adequately powered multicentre RCTs to robustly address the role of immunomodulation in women with RIF. There is also an urgent need for standardised screening tests for immune disorders that could preclude implantation.

Analysis of the risk factors in patients with unexplained recurrent spontaneous abortion

PROBLEM

We aimed to explore the risk factors in patients with unexplained recurrent spontaneous abortion (URSA) and to provide a basis for clinically targeted therapy.

METHOD OF STUDY

This case-control study comprised 202 patients with URSA treated at our hospital and 115 women in early pregnancy with a normal birth history during the same period. After procuring the data we conducted a multivariate logistic regression analysis of risk factors related to URSA.

RESULTS

Logistic regression analysis showed (i) that the number of spontaneous abortions (SAs; odds ratio [OR] = 492.123), the levels of autoantibodies (OR = 19.322) and tumor necrosis factor alpha (TNF-α; OR = 9.615), and the CT and TT genotypes of methylenetetrahydrofolate reductase (MTHFR) C677T (OR = 6.217 and 15.009, respectively) were risk factors for URSA and (ii) that 25-hydroxyvitamin D (25-(OH)D; OR = 0.919) was a protective factor. The most important risk factor was a history of one or more SAs, with the risk of pregnancy loss increasing 491.123-fold. Every unit increase in serum 25-(OH)D reduced the risk of SA by 8.1%.

CONCLUSIONS

The risk factors for URSA included the number of SAs, the levels of autoantibodies and TNF-α, and the MTHFR C677T T allele; 25-(OH)D was a protective factor. We recommend that women diagnosed with URSA receive intervention as soon as possible so as to actively reduce the incidence of recurrent SA.

Pregnancy by Oocyte Donation: Reviewing Fetal-Maternal Risks and Complications

Oocyte donation (OD) has greatly improved over the last three decades, becoming a preferred practice of assisted reproductive technology (ART) for infertile women wishing for motherhood. Through OD, indeed, it has become possible to overcome the physiological limitation due to the ovarian reserve (OR) exhaustion as well as the poor gamete reliability which parallels the increasing age of women. However, despite the great scientific contribution related to the success of OD in the field of infertility, this practice seems to be associated with a higher rate of major risky events during pregnancy as recurrent miscarriage, infections and placental diseases including gestational hypertension, pre-eclampsia and post-partum hemorrhage, as well as several maternal-fetal complications due to gametes manipulation and immune system interaction. Here, we will revisit this questioned topic since a number of studies in the medical literature focus on the successful aspects of the OD procedure in terms of pregnancy rate without, however, neglecting the risks and complications potentially linked to external manipulation or heterologous implantation.

Increased cytotoxic natural killer cells in the endometrium alone cannot be considered the immunological cause of recurrent miscarriage

OBJECTIVE

To study the distribution and gene expression of endometrial immune cell populations, especially natural killer (NK) subsets, between assisted reproductive technology patients and healthy donors and explore a possible relationship of these results with patients' killer cell immunoglobulin-like receptor (KIR) genotypes and KIR-human antigen leukocyte-C (HLA-C) binding.

DESIGN

Prospective observational cohort study.

SETTING

Clinic and university laboratories.

PATIENT(S)

Participants included 39 women with recurrent miscarriages who had undergone in vitro fertilization cycles with donated oocytes and 21 healthy oocyte donors with proven fertility.

INTERVENTION(S)

Endometrial biopsy samples were collected from both patients and donors, and the KIR genotypes of the assisted reproductive technology patients were analyzed.

MAIN OUTCOME MEASURE(S)

Endometrial gene expression (cluster of differentiation [CD] antigens and anti-inflammatory and proinflammatory interleukins) and the number and percentage of regulatory T and NK cell populations in patients and donors were determined. Subsequently, the results obtained were categorized in the group of patients by KIR genotype. Killer cell immunoglobulin-like receptor-HLA-C binding was also examined in patients, considering their KIRs.

RESULT(S)

A higher percentage of CD56dimCD16+ NK cells were observed in patients than those in healthy donors. Nevertheless, when categorizing patients by KIR genotype and comparing the KIR AA (35.9%), AB (43.6%), and BB (20.5%) groups, no statistically significant difference was observed in either endometrial gene expression or any of the immune cell populations analyzed. Finally, no differences in binding between KIR and HLA-C molecules were registered among these 3 sets of patients.

CONCLUSION(S)

The reported increase in the number of NK cells with a cytotoxic profile in the endometrium of women with a history of recurrent miscarriages cannot alone explain these events because no relationship is observed between such cellular increase and the KIR genotypes, which individually, and in combination with the different HLA-C alleles, have also been associated, by previous studies, with negative reproductive outcomes.

CLINICAL TRIAL REGISTRATION NUMBER

1405-MAD-025-JG.

Co-administration of tacrolimus and low molecular weight heparin in patients with a history of implantation failure and elevated peripheral blood natural killer cell proportion

AIM

To investigate the therapeutic effect of co-administration of tacrolimus (TAC) and low-molecular-weight heparin (LMWH) or LMWH only on pregnancy outcomes in the female with a history of implantation failure and elevated peripheral blood natural killer (pNK) cell proportion in frozen-thawed embryo transfer cycles.

METHODS

To evaluate the pregnancy parameters for 249 patients with ≥2 implantation failures and pNK cell proportion ≥12% by analyzing a retrospective observational cohort study. Sixty patients had received the co-administration TAC and LMWH (TAC & LMWH group), 85 others had only taken LMWH (LWMH group), and the rest did not take any particular drugs (control group).

RESULTS

The experimental finding indicated that the TAC & LMWH group and the LMWH group showed higher clinical pregnancy rates than the control group (p < 0.05), and TAC & LMWH group had a much higher live birth rate. According to the binary logistic regression analysis, the combination of TAC and LMWH was conducive to clinical pregnancy and live birth rate and reduced the possibility of miscarriage. It would not affect the result of spontaneous abortion and live birth, although the LMWH was only beneficial to clinical pregnancy. In addition, these findings were similar for these three groups' obstetrical and neonatal outcomes.

CONCLUSIONS

The combination of TAC and LMWH can improve clinical pregnancy and live birth rates and reduce the risk of spontaneous miscarriage in patients with a history of implantation failure and elevated pNK ratio. LMWH is also beneficial to clinical pregnancy.

Identification and validation of immune cells and hub genes alterations in recurrent implantation failure: A GEO data mining study

Introduction: Recurrent implantation failure (RIF) is a distressing problem in assisted reproductive technology (ART). Immunity plays a vital role in recurrent implantation failure (RIF) occurrence and development, but its underlying mechanism still needs to be fully elucidated. Through bioinformatics analysis, this study aims to identify the RIF-associated immune cell types and immune-related genes. Methods: The differentially expressed genes (DEGs) were screened based on RIF-associated Gene Expression Omnibus (GEO) datasets. Then, the enrichment analysis and protein-protein interaction (PPI) analysis were conducted with the DEGs. The RIF-associated immune cell types were clarified by combining single sample gene set enrichment analysis (ssGSEA) and CIBERSORT. Differentially expressed immune cell types-related modules were identified by weighted gene co-expression network analysis (WGCNA) and local maximal quasi-clique merger (lmQCM) analysis. The overlapping genes between DEGs and genes contained by modules mentioned above were delineated as candidate hub genes and validated in another two external datasets. Finally, the microRNAs (miRNAs) and long non-coding RNAs (lncRNAs) that interacted with hub genes were predicted, and the competing endogenous RNA (ceRNA) regulatory network was structured. Results: In the present study, we collected 324 DEGs between RIF and the control group, which functions were mainly enriched in immune-related signaling pathways. Regarding differential cell types, the RIF group had a higher proportion of activated memory CD4 T cells and a lower proportion of γδ T cells in the endometrial tissue. Finally, three immune-related hub genes (ALOX5AP, SLC7A7, and PTGS2) were identified and verified to effectively discriminate RIF from control individuals with a specificity rate of 90.8% and a sensitivity rate of 90.8%. In addition, we constructed a key ceRNA network that is expected to mediate molecular mechanisms in RIF. Conclusion: Our study identified the intricate correlation between immune cell types and RIF and provided new immune-related hub genes that offer promising diagnostic and therapeutic targets for RIF.

Prednisolone and enoxaparin (clexane) therapy ('the Bondi protocol') for repeated IVF failure

PROBLEM

What is the impact of an empirical immune therapy protocol of prednisolone and enoxaparin (clexane) (the 'Bondi protocol') on women with repeated in vitro fertilization (IVF) failure?

METHOD OF STUDY

This was a retrospective review of live birth outcomes conducted on all transfer cycles performed by a single clinician (GS) at IVFAustralia between February 2016 and April 2020. This study consisted of 1786 transfer cycles, including 460 cycles treated with the Bondi protocol and 1326 without. Women with repeated IVF failure were given the Bondi protocol based on blood NK cell activity. Primary outcome was live birth and statistical analysis was performed with GraphPad Prism software with significance for P-values < .05.

RESULTS

Overall 'Bondi' and 'normal' protocol cycles had similar rates of IVF/ICSI, fresh/frozen transfers and use of preimplantation genetic testing (PGT). Women given the Bondi protocol were older, had more previous cycles and had higher blood NK cell activity. There was no significant difference in live birth rates (Bondi 26%, normal 28%). Bondi protocol live birth rates per transfer cycle were as high as 40% in patients under 38 years old. The Bondi protocol was more effective as NK activity increased from 'normal' to 'borderline' to 'high'. For high NK cell activity levels, live birth rates were over four times higher for women on the Bondi protocol (28%) than those on normal protocols (6%, P = .0007).

CONCLUSION

This study describes a simple and relatively safe immune therapy protocol that may improve IVF success rates in women with evidence of immune dysfunction.

Clinical outcome of intrauterine administration of peripheral mononuclear cells or human chorionic gonadotropin in unexplained implantation failure

PROBLEM

Intrauterine administration of autologous peripheral blood mononuclear cells (PBMCs) or human chorionic gonadotropin (hCG) has been proposed to facilitate embryo implantation, while its effect on clinical outcome of women with previous implantation failure (RIF) in frozen/thawed embryo transfer (FET) cycles is still unclear.

METHOD OF STUDY

A total 523 patients having not experienced successful clinical pregnancy were enrolled in our study, including 207 repeat implantation failure (RIF) patients, and 316 patients with previous implantation failures but failed to meet the diagnostic criteria for RIF (non-RIF). Autologous PBMCs were cultured with hCG for 4 h in the hCG-activated PBMC-treated group (n = 73 in RIF patients, n = 112 in non-RIF patients), and then intrauterine administered 2 days before FET. In the hCG-treated group (n = 67 in RIF patients, n = 100 in non-RIF patients), recombinant hCG was administered 2 days before FET. The control group (n = 67 in RIF patients, n = 104 in non-RIF patients) underwent FET without intrauterine administration.

RESULTS

In RIF patients, the clinical pregnancy rate of the above three groups are 56.16%, 53.73%, and 43.28%, respectively (p = .276). The implantation rate and live birth rate showed no significant differences (p > .05). For non-RIF patients, higher clinical pregnancy rate was also seen in PBMC intrauterine group (57.15%) and hCG intrauterine group (58.00%) than controls (50.96%) but without statistical significance. There were no significant differences of implantation rate and live birth rate (p > .05).

CONCLUSION

Intrauterine administration of hCG-activated PBMC and hCG did not improve clinical outcomes for both RIF and non-RIF patients before FET embryo transfer.

Intralipid therapy and adverse reproductive outcome: is there any evidence?

Controversy exists regarding the benefits of intravenous intralipid therapy in patients with a poor reproductive history. It is frequently reported that there is no evidence to support the effectiveness, utility or safety for this treatment. While individual studies may be perceived as weak, a systematic review and meta-analysis were performed to determine if there is any advantage to patients. PubMed, Embase and Scopus searches were performed with the target populations being either recurrent pregnancy loss (RPL), or recurrent implantation failure (RIF) undergoing assisted reproductive technology (ART) and receiving intralipid infusions. These cohorts were compared with either placebo, no intervention or alternative treatments. The most relevant outcome measures were considered to be clinical pregnancy rate (CPR), live birth rate (LBR), implantation rate (IR) and miscarriage rate (MR). Twelve studies encompassing 2676 participants met the criteria for selection and were included and reviewed. Treatment of the target population with intralipid led to an improvement in IR (Odds Ratio (OR): 2.97, 2.05–4.29), pregnancy rate (OR: 1.64, 1.31–2.04), and LBR (OR: 2.36, 1.75–3.17), with a reduction in MR (OR: 0.2, 0.14–0.30). Although intravenous intralipid is not recommended as a routine treatment for recurrent miscarriage or implantation failure, there is enough data to suggest consideration in selected patients where routine testing is unremarkable, standard treatments have failed and immunological risk factors are present. The presence of abnormal uterine natural killer (uNK) cells needs more study as a target marker to determine those who could benefit.

Recurrent Implantation Failure May Be Identified by a Combination of Diagnostic Biomarkers: An Analysis of Peripheral Blood Lymphocyte Subsets

BACKGROUND

Recurrent implantation failure (RIF) is a challenge during assisted reproductive technology (ART). In the present study, potential diagnostic biomarkers for the immune status of peripheral blood lymphocyte subsets in patients with RIF were analyzed, with the aim of identifying novel biomarkers that may predict RIF.

METHODS

A total of 41 participants, including 21 women with RIF and 20 fertile controls, were included in the present study. Functional analysis was performed and the cytokine status of natural killer (NK), T, CD8+ T, T helper (Th), and γδ T cells which are lymphocyte subsets in peripheral blood was measured using flow cytometry. Binary logistic regression analysis adjusted for T follicular helper 1 (Tfh1), Tfh2, Tfh17, and early NK cells was performed to determine the relationship between the peripheral blood lymphocyte subsets and RIF. Potential diagnostic biomarkers were assessed by logistic regression analysis and receiver operating characteristic curves.

RESULTS

There were significantly more Tfh1, Tfh17, and NK cells in the RIF group compared with the control group (all P < 0.05). However, the percentage of T, regulatory T (Tregs), and Tfh2 cells, as well as early inhibitory NK cells, was significantly lower in the RIF group compared with the control group (all P < 0.05). Following logistics regression analysis, Treg, Tfh17, and early inhibitory NK cells exhibited significant differences between the two groups. Combination diagnosis using these 3 biomarkers had a higher area under the curve of 0.900 (95% confidence interval: 0.808-0.992, P < 0.001) in the RIF group compared with that in the control group.

CONCLUSION

T, Tregs, Tfh1, Tfh2, Tfh17, NK cells, and early inhibitory NK cells may play important regulatory roles in embryo implantation. The combination of 3 molecular markers (Treg, Tfh17, and early inhibitory NK cells) could provide a high diagnostic value for women with RIF, thus providing novel potential biomarkers for RIF in ART. The present findings could provide a reference either for the clinical treatment of patients with RIF or for future large, well-designed studies.

Glucocorticoid therapy in assisted reproduction

As glucocorticoids are well-known as important regulators of stress and the immune system, their function and clinical use have elicited substantial interest in the field of reproduction. In particular, the effect of glucocorticoid therapy on endometrial receptivity during assisted reproduction, including in vitro fertilization (IVF) cycles, has led to a great deal of interest and controversy. However, previous studies have not been able to provide consistent and reliable evidence due to their small, non-controlled designs and use of different criteria. Considering the potential risk of exposure to glucocorticoids for mothers and fetuses in early pregnancy, the use of glucocorticoids in IVF cycles should be carefully evaluated, including the balance between risk and benefit. To date, there is no conclusive evidence that the use of glucocorticoids improves the pregnancy rate in IVF cycles with unselected subjects, and a further investigation should be considered with a proper study design.

Immunological Testing in Assisted Reproductive Technology

Fetal implantation requires carefully orchestrated involvement of the maternal immune system. Aberrant function within implantation has been suggested as a cause of implantation failure. The emergence of immunological theories of miscarriage has led to immunological testing as an adjuvant treatment in assisted reproductive technology; however, it remains controversial, with mixed evidence both for immunological cause and the benefits of immunological testing. Literature on common methods of immunological testing within assisted reproductive technology is reviewed including those of peripheral and uterine natural killer cells, chronic endometritis, and T-helper cells cytokine ratio. There is little consensus in the evidence on immunological testing in the context of recurrent implantation failure. The field is limited by a lack of uniformity in approach to testing and heterogeneity of the pathophysiological cause. Nevertheless, the maternal immune system is heavily involved in implantation and the new era of personalized medicine ensures that a more defined approach to immunological testing will be achieved.

Immunotherapy to improve pregnancy outcome in women with abnormal natural killer cell levels/activity and recurrent miscarriage or implantation failure: A systematic review and meta-analysis

There is a trend towards offering immunotherapy to women with unexplained reproductive failure based on abnormal Natural Killer (NK) cell levels. Previous systematic reviews evaluating immunotherapy usage have not focused on women with abnormal level of NK cells. To address the gap in literature, this systematic review aims to evaluate the efficacy of immunotherapy to improve pregnancy outcome in women with recurrent miscarriage (RM) or implantation failure (RIF) specifically selected based on abnormal levels and/or activity of NK cells. Six databases were searched for peer-reviewed studies following PRISMA guidelines. Risk of bias assessment was conducted using RoB2 for randomized controlled trials (RCT) and ROBINS-I for non-RCT. Of 1025 studies identified, seven studies on intravenous immunoglobulin (IVIG) (four), prednisolone (one), etanercept (one) and intralipid (one) were included. Meta-analysis of the non-RCT IVIG studies (557 participants; 312 intervention, 245 controls) showed livebirth in favour of intervention (RR 2.57; 95 % CI = 1.79-3.69; p < 0.05), however there were significant heterogeneity (I² = 62 %) and moderate to severe risk of bias in these studies. Individual RCTs reported improved livebirth outcome in etanercept, intralipid and prednisolone and this was significant in the former two (p < 0.05). In conclusion, there may be some benefit of immunotherapy, but paucity of high quality evidence means that it is not possible to support the use of immunotherapy even when selected based on abnormal NK cell level/activity. Further research with application of scientifically validated immunological biomarkers in well-planned large scale RCTs will determine whether immunotherapy is beneficial in this subpopulation of women.

Novel predictive and therapeutic options for better pregnancy outcome in frozen embryo transfer cycles

Since 1978, in the first decades of in vitro fertilization (IVF), the use of ovarian hyperstimulation allowed for the development and transfer of multiple embryos. As IVF technology improved, the number of multiple pregnancies increased, which led to gradual reduction in the number of embryos that were transferred. Embryo freezing (vitrification) was recommended to allow subsequent transfer if the fresh cycle was unsuccessful. However, experimentation has continued to improve pregnancy outcomes. We discuss here the significance of frozen embryo transfer cycle and the impact of uterine and peripheral immunity dominated by NK cells and regulatory T cells and human chorionic gonadotropin on pregnancy outcome in this innovative mode of IVF therapy.

Intrauterine administration of autologous hCG- activated peripheral blood mononuclear cells improves pregnancy outcomes in patients with recurrent implantation failure; A double-blind, randomized control trial study

We aimed to investigate the effect of intrauterine administration of autologous hCG-activated PBMCs in RIF women with low Th-17/Treg cell ratio. 248 women with a history of implantation failure volunteered to receive PBMC-therapy. After immunologic consultation and doing flow cytometry analysis, 100 women with at least three IVF/ET failure who had low Th-17/Treg ratio in comparison with healthy control were enrolled in this study. These 100 patients were randomly divided into two groups as PBMC receiving (n = 50) and controls (n = 50). Then PBMCs were obtained from patients and treated with hCG for 48 h. Afterward, PBMCs were administered into the uterine cavity of the patient in the study group, two days before ET. The concentration of inflammatory cytokines was examined in the supernatant of cultured PBMCs after 2, 24, and 48 h of incubation using the ELISA method. The frequency of Th-17, Treg, and the Th-17/Treg ratio was significantly lower in RIF women than the healthy controls (P < 0.0001). The secretion of inflammatory cytokines was significantly higher after 48 h compared to 2 and 24 h (P < 0.0001). The pregnancy and live birth rate were significantly increased in women undergoing the PBMC-therapy compared to control (PBS-injecting) group (P = 0.032 and P = 0.047, respectively). The miscarriage rate was considerably lower in PBMC-therapy group (P = 0.029). Our findings suggest that intrauterine administration of autologous in vitro hCG-activated PBMCs improves pregnancy outcomes in patients with at least three IVF/ET failures.

Potential impact of maternal vitamin D status on peripheral blood and endometrium cellular immunity in women with recurrent implantation failure

PROBLEM

This study aims to evaluate the modulatory effects of vitamin D on peripheral blood and endometrial cellular immunity in women with recurrent implantation failure (RIF).

METHOD OF STUDY

One hundred and fifty-four women with RIF were identified at a fertility center from January 2018 and March 2019. Blood and endometrium samples were collected during the mid-luteal phase before IVF treatment or pregnancy. The serum vitamin D status, NK cell cytotoxicity, Th1 cytokine production, and endometrial immune cells were detected before and after vitamin D supplementation.

RESULTS

The NK cell cytotoxicity at an effector:target (E:T) ratio of 50:1 or 25:1 was significantly higher in vitamin D insufficiency group (VDI) than those in vitamin D normal group (VDN) (P < .05 each). The percentage of IFN-γ- or TNF-α-producing Th cells was significantly increased in VDI or vitamin D deficiency group (VDD) when compared with VDN (P < .05 each). The percentage of CD68⁺ macrophages on all endometrial cells in VDI and VDD was significantly higher than in VDN (P < .05 each), while no significant differences in the percentage of other endometrial immune cells among the three groups were observed. This dysregulation was significantly reduced with vitamin D supplementation.

CONCLUSION

Our findings highlighted that vitamin D may have an important role in the regulation of not only systemic but also local immune response for optimization of maternal tolerance for implantation in women with RIF. Pre-conception optimization of vitamin D status should be considered in women with RIF.

A randomized controlled trial of etanercept in the treatment of refractory recurrent spontaneous abortion with innate immune disorders

OBJECTIVE

To evaluate the effectiveness of etanercept in the treatment of refractory recurrent spontaneous abortion with innate immune disorders.

MATERIALS AND METHODS

A randomized controlled trial in patients with refractory innate immune RSA was conducted in our hospital. 188 patients were selected, all with at least 4 consecutive miscarriages and caused by innate immunity disorders. Patients were randomly allocated into 2 groups. One group (n = 95) used etanercept 25 mg per week starting from the first day after menstruation, while the other (n = 93) with placebo. Delivery of a healthy baby without malformations was regarded as the primary outcome.

RESULTS

In etanercept group, 85 (89.47%) patients delivered a healthy baby, while in placebo group, this number was only 67 (72.04%) [P = 0.01, OR = 3.30; 95% CI(1.49～7.32)]. Significantly lower levels of TNF-α and NK cell activity were observed in gestation weeks 4-10 in etanercept group versus placebo group (P < 0.05).

CONCLUSION

The results provide a proof of principle that etanercept can be an attractive therapeutic strategy for refractory innate immune RSA.

Intralipid Immunotherapy for Repeated IVF Failure

The intravenous fat emulsion, intralipid, has been hypothesised to be an effective and safe treatment for repeated in vitro fertilisation (IVF), implantation failure and pregnancy loss. This exploratory, retrospective cohort study determined pregnancy outcomes and documented adverse events associated with intralipid use. Ninety-three women were identified as having received intralipid for a history of repeated unsuccessful IVF cycles and pre-viable pregnancy loss in two Australian IVF units that independently recruited between October 2014 and July 2016. Pregnancy outcomes and adverse events were recorded in fresh and frozen embryo transfer cycles in which the infusion was administered. The 93 women who received intralipid had a clinical pregnancy rate of 40.0%, compared with 35.0% in 651 age-matched controls undergoing IVF, which was not significantly different. The intralipid group had a livebirth rate of 35.7%. Apart from flushing, which was experienced by one individual, there were no adverse events associated with intralipid use. As a prelude to definitive evidence of benefit, we did not identify a safety concern or reduced pregnancy rates in intralipid users compared to controls. Indeed, these outcomes were better than expected in a poor prognosis group. This data supports an argument for large, randomised controlled trials to determine the benefit of intralipid in the treatment of recurrent implantation failure or miscarriage.

In vitro fertilization add-ons for the endometrium: it doesn't add-up

The probability of live birth from an in vitro fertilization (IVF) cycle is modest. Many additional treatments (add-ons) are available which promise to improve the success of IVF. This review summarizes the current evidence for common IVF add-ons which are suggested to improve endometrial receptivity. Systematic reviews of randomized controlled trials and individual trials were included. Five add-ons were included: immune therapies, endometrial scratching, endometrial receptivity array, uterine artery vasodilation, and human chorionic gonadotropin instillation. The results suggest there is no robust evidence that these add-ons are effective or safe. Many IVF add-ons are costly, consuming precious resources which may be better spent on evidence-based treatments or further IVF. Large randomized controlled trials and appropriate safety assessment should be mandatory before the introduction of IVF add-ons into routine practice.

The number and cytotoxicity and the expression of cytotoxicity-related molecules in peripheral natural killer (NK) cells do not predict the repeated implantation failure (RIF) for the in vitro fertilization patients

Natural killer (NK) cells are thought to play a key role in the successful establishment of a pregnancy by facilitating immunological adaptation of the semi-allogeneic developing embryo. The aim of this study was to explore the cell number, immunophenotypic characteristics, and activities of peripheral blood NK cells in women with repeated implantation failure (RIF). Peripheral blood was obtained from 27 women with RIF and 11 healthy, fertile controls during the middle luteal phase of the menstrual cycle. CD3^- CD56⁺ NK cells were quantified and analyzed by flow cytometry for the expression of cytolytic molecules (granzyme B, granulysin, and perforin) as well as cell surface receptors responsible for NK cell activation or inhibition (NKG2D, NKp30, NKp46, CD158a, CD158b). NK cytotoxicity was measured at three effector-to-target cell ratios. Women with RIF and fertile controls did not differ significantly in the percentage of circulating CD3⁻CD56⁺ NK cells, or in the proportions of these cells that expressed granzyme B, granulysin, or perforin. The two groups also did not differ significantly in the proportions of NK cells expressing the receptors NKG2D, NKp30, NKp46, CD158a or CD158b. General linear model analysis showed that NK cytotoxicity increased with effector-to-target cell ratio. However, NK cytotoxicity did not differ significantly between patients with RIF and fertile controls. These results suggest that RIF is not associated with significant alterations in the number or function of peripheral blood NK cells.

Recurrent Implantation Failure-update overview on etiology, diagnosis, treatment and future directions

Recurrent implantation failure (RIF) refers to cases in which women have had three failed in vitro fertilization (IVF) attempts with good quality embryos. The definition should also take advanced maternal age and embryo stage into consideration. The failure of embryo implantation can be a consequence of uterine, male, or embryo factors, or the specific type of IVF protocol. These cases should be investigated to determine the most likely etiologies of the condition, as this is a complex problem with several variables. There are multiple risk factors for recurrent implantation failure including advanced maternal age, smoking status of both parents, elevated body mass index, and stress levels. Immunological factors such as cytokine levels and presence of specific autoantibodies should be examined, as well as any infectious organisms in the uterus leading to chronic endometritis. Uterine pathologies such as polyps and myomas as well as congenital anatomical anomalies should be ruled out. Sperm analysis, pre-implantation genetic screening and endometrial receptivity should be considered and evaluated, and IVF protocols should be tailored to specific patients or patient populations. Treatment approaches should be directed toward individual patient cases. In addition, we suggest considering a new initial step in approach to patients with RIF, individualized planned activities to activate the brain's reward system in attempt to improve immunological balance in the body.

First do no harm: uterine natural killer (NK) cells in assisted reproduction

Natural killer (NK) cells are a type of lymphocyte circulating in peripheral blood named because of their effector functions in killing target cells. Immune cells that share similar phenotypic characteristics but are poor killers populate the uterine lining at implantation and during early pregnancy when the placenta is established. The functions of these uterine NK (uNK) cells are essentially unknown but available data point to a role in regulating placentation in concert with other elements of the decidua and invading trophoblast cells. Despite the lack of scientific rationale and advice from clinical governing bodies, such as the Human Fertilisation and Embryology Authority, an increasing range of tests and therapies are still offered to women undergoing IVF or attending recurrent miscarriage clinics based on the myth that uterine NK cells need suppressing to prevent damage to the embryo. New treatments can be introduced at whim with subsequent demands for expensive trials to prove/disprove their efficacy. The evidence that targeting uNK or peripheral blood NK cells assists women with recurrent pregnancy failure is lacking. Healthcare professionals and patients should very carefully evaluate the practice of immunomodulation to enhance pregnancy outcome. A discussion on how to move towards stricter regulation of immunotherapy in non-hospital settings is now needed because it is clear that the potential risks and costs of these therapies outweigh any benefits.

Intrauterine insemination of cultured peripheral blood mononuclear cells prior to embryo transfer improves clinical outcome for patients with repeated implantation failures

Implantation failure is a major limiting factor in assisted reproduction improvement. Dysfunction of embryo–maternal immuno-tolerance pathways may be responsible for repeated implantation failures. This fact is supported by immunotropic theory stipulating that maternal immune cells, essentially uterine CD56+ natural killer cells, are determinants of implantation success. In order to test this hypothesis, we applied endometrium immuno-modulation prior to fresh embryo transfer for patients with repeated implantation failures. Peripheral blood mononuclear cells were isolated from repeated implantation failure patients undergoing assisted reproductive technology cycles. On the day of ovulation induction, cells were isolated and then cultured for 3 days and transferred into the endometrium cavity prior to fresh embryo transfer. This immunotherapy was performed on 27 patients with repeated implantation failures and compared with another 27 patients who served as controls. Implantation and clinical pregnancy were increased significantly in the peripheral blood mononuclear cell test versus control (21.54, 44.44 vs. 8.62, 14.81%). This finding suggests a clear role for endometrium immuno-modulation and the inflammation process in implantation success. Our study showed the feasibility of intrauterine administration of autologous peripheral blood mononuclear cells as an effective therapy to improve clinical outcomes for patients with repeated implantation failures and who are undergoing in vitro fertilization cycles.

Immunomodulatory treatment with intravenous immunoglobulin and prednisone in patients with recurrent miscarriage and implantation failure after in vitro fertilization/intracytoplasmic sperm injection

OBJECTIVE

To assess outcome in terms of live-birth rate after fresh or frozen IVF/intracytoplasmic sperm injection assisted reproductive technology (ART) cycles where immunomodulation was given to patients with recurrent pregnancy loss after prior ART treatments.

DESIGN

Retrospective cohort study.

SETTING

Tertiary care university hospital.

PATIENT(S)

Fifty-two patients with a history of at least three consecutive pregnancy losses after ART who underwent at least one further ART cycle with concurrent immunomodulation in 2003-2012.

INTERVENTION(S)

Immunomodulation with IV immunoglobulin and prednisone starting from before ET and continuing in the first trimester if pregnancy was established.

MAIN OUTCOME MEASURE(S)

Live-birth rate per ET and cumulative live-birth rate after up to five ETs.

RESULT(S)

Nineteen patients (36.5%) achieved a live birth after the first ET with immunomodulation, and a total of 32 patients achieved a live birth in the study period, resulting in a cumulative live-birth rate of 61.5%. There was no significant difference in baseline and immunological parameters between the patients achieving a live birth or not. The live-birth rate after the first immunomodulated ART cycle in our patients is higher than that reported in a previous study.

CONCLUSION(S)

Immunomodulation with a combination of IV immunoglobulin and prednisone is a promising treatment for recurrent pregnancy loss after ART, but randomized placebo-controlled trials are needed.

Female asthma has a negative effect on fertility: what is the connection?

Reproductive changes such as impaired fertility and adverse pregnancy outcomes have been related to female asthma. We recently found that time to pregnancy is prolonged in asthmatic females especially in women with moderate to severe asthma and in those above 30 years of age. Despite their reproductive difficulties the asthmatics ultimately conceived just as many biological children as healthy throughout their reproductive lives. This knowledge therefore raises questions about how asthma affects fertility pathophysiologically. The purpose of this review is to describe the existing knowledge in this field and suggest hypotheses of causal relationships, which may form the basis for future studies in this field. The aim is, in particular, in the literature to examine whether there is any evidence to suggest that the systemic inflammation that characterizes asthma, can affect fertility. The issue is potentially clinically important for asthmatic, infertile individuals and society because treatment of the general systemic inflammation associated with the asthmatic disease combined with hormone stimulation might be the optimal target for an effective infertility therapy, possibly decreasing the need for in vitro fertilization.

Natural killer cells in female infertility and recurrent miscarriage: a systematic review and meta-analysis

INTRODUCTION Embryo implantation is a complex process involving maternal hormonal changes, immune responses and maturational events in the embryo. A pregnancy could fail when these events are not synchronized. It is speculated that in women, an elevation of natural killer (NK) cells may have an effect on reproductive performance, and NK cell levels in blood are currently being used as a diagnostic test to guide the initiation of therapies in patients with infertility. METHODS We conducted a systematic review to evaluate the (i) levels of NK cells in blood and endometrium in infertile versus fertile women, (ii) association between NK cells and IVF outcome, (iii) levels of NK cells in blood and endometrium in women with recurrent miscarriage (RM) versus controls. The following electronic databases were searched: Medline, EMBASE, Cochrane Library, Web of Science and National Research Register. RESULTS A total of 22 studies were included. Meta-analysis of studies that evaluated peripheral and uterine NK (uNK) cell percentages in infertile versus fertile women showed no significant difference between the two groups [standardized mean difference (SMD) -0.33; 95% confidence intervals (CI) -1.06, 0.4; P = 0.37; SMD -1.82; 95% CI -4.80, 1.17; P = 0.23 respectively]. Pooling of studies that reported peripheral NK cells as numbers showed significantly higher NK cell numbers in infertile women compared with fertile controls (SMD 3.16; 95% CI 1.07, 5.24; P = 0.003). Meta-analysis of studies that evaluated the role of NK cells in IVF outcome showed no significant difference in live birth rates in women with elevated NK cells or NK cell activity compared with women without elevated peripheral NK cells or NK cell activity (NK activity assessed using a cytotoxicity assay) (relative risk 0.57; 95% CI 0.06, 5.22; P = 0.62). Meta-analysis of studies that evaluated peripheral NK cell percentages in women with RM versus controls showed significantly higher NK cell percentages in women with RM (SMD 1.36; 95% CI 0.04, 2.69; P = 0.04). Meta-analysis of studies that evaluated peripheral NK cell numbers showed significantly higher NK cell numbers in women with RM compared with controls (SMD 0.81; 95% CI 0.47, 1.16; P < 0.00001). Meta-analysis of studies that evaluated uNK cells showed no significant difference in women with RM compared with controls (SMD 0.40; 95% CI -1.24, 2.04; P = 0.63). CONCLUSIONS Further research is needed before NK cell assessment can be recommended as a diagnostic tool in the context of female infertility or RM. There is no clear explanation as to why the results differ when data for NK cells are expressed as numbers or a percentage. On the basis of current evidence, NK cell analysis and immune therapy should be offered only in the context of clinical research.

Natural killer cells and their activation status in normal pregnancy

Increased peripheral blood-activated NK cell counts are associated with increased risk of miscarriage and failed in vitro fertilization treatment. However, assessment of activated peripheral NK cells in normal and pathological pregnancies beyond implantation and early miscarriage has not been described. Total CD69 expressing NK cells counts were measured by flow cytometry in healthy women with singleton pregnancies, including 45 at 11⁺⁶–13⁺⁶ weeks' gestation, 46 at 20⁺⁰–22⁺⁴ weeks, and 42 at 31⁺⁶–33⁺⁵ weeks. The number of peripheral blood NK cells decreased, whereas the percentage of activated CD69 expressing NK cells increased from the first to the third trimester of pregnancy. This study shows the course of peripheral blood NK cells and activated CD69 expressing NK cells in uncomplicated nulliparous singleton pregnancies. This is a first step in understanding their implication in pathological pregnancies.