Relating the number of human leucocytes antigen mismatches to pregnancy complications in oocyte donation pregnancies: study protocol for a prospective multicentre cohort study (DONOR study)

Oocyte donation pregnancies with high fetal-maternal immunogenetic dissimilarity show alterations in the maternal peripheral immunoregulatory response

Oocyte donation (OD) pregnancies result in increased fetal-maternal immunogenetic dissimilarity due to paternal and donor-derived genes. Higher fetal-maternal HLA mismatches are correlated with preeclampsia. Therefore, this study explored the maternal immune response, focusing on regulatory T cells (Tregs) during low versus high allogeneic pregnancies, and healthy versus preeclamptic OD pregnancies. Ten healthy and five preeclamptic OD pregnancies were included. Maternal peripheral blood was collected at different stages of pregnancy. Fetal-maternal HLA mismatches were determined, and immunophenotyping of peripheral blood mononuclear cells was conducted using a 22-colour spectral flow cytometry panel. Cytokines and hormones were detected in maternal plasma using ELISA and Luminex assays. The findings show similarities, but also distinct differences between low and high allogeneic healthy OD pregnancies. Early high allogeneic OD pregnancy showed reduction in Tregs, and CD8+ T cells, alongside lower percentage of effector/memory Tregs expressing PD-1 and Helios. Additionally, high allogeneic OD pregnancies showed increased IL-6 and progesterone in the first trimester. These variations suggest a different mode of immune regulation in early high allogeneic OD pregnancies, possibly to maintain healthy pregnancy. Further comparative analyses revealed reduced CD45RO+CTLA-4+ Tregs and increased latent TGF-β1 and -β2 levels in early preeclamptic compared to healthy OD pregnancy. Late-stage preeclamptic OD pregnancies exhibited higher frequencies of CD45RO+TIGIT+ Tregs and higher levels of TNFα, indicating both a regulatory and pro-inflammatory environment. Overall, this study sheds light on the course of various immunoregulatory key players in OD pregnancy, and expands knowledge on maternal tolerance in this particular type of pregnancy.

Development of the DONOR prediction model on the risk of hypertensive complications in oocyte donation pregnancy: study protocol for a multicentre cohort study in the Netherlands

INTRODUCTION

Oocyte donation (OD) pregnancy is accompanied by a high incidence of hypertensive complications, with serious consequences for mother and child. Optimal care management, involving early recognition, optimisation of suitable treatment options and possibly eventually also prevention, is in high demand. Prediction of patient-specific risk factors for hypertensive complications in OD can provide the basis for this. The current project aims to establish the first prediction model on the risk of hypertensive complications in OD pregnancy.

METHODS AND ANALYSIS

The present study is conducted within the DONation of Oocytes in Reproduction project. For this multicentre cohort study, at least 541 OD pregnancies will be recruited. Baseline characteristics and obstetric data will be collected. Additionally, one sample of maternal peripheral blood and umbilical cord blood after delivery or a saliva sample from the child will be obtained, in order to determine the number of fetal-maternal human leucocyte antigen mismatches. Following data collection, a multivariate logistic regression model will be developed for the binary outcome hypertensive complication 'yes' and 'no'. The Prediction model Risk Of Bias ASsessment Tool will be used as guide to minimise the risk of bias. The study will be reported in line with the 'Transparent Reporting of a multivariable prediction model for Individual Prognosis Or Diagnosis' guideline. Discrimination and calibration will be determined to assess model performance. Internal validation will be performed using the bootstrapping method. External validation will be performed with the 'DONation of Oocytes in Reproduction individual participant data' dataset.

ETHICS AND DISSEMINATION

This study is approved by the Medical Ethics Committee LDD (Leiden, Den Haag, Delft), with protocol number P16.048 and general assessment registration (ABR) number NL56308.058.16. Further results will be shared through peer-reviewed journals and international conferences.

Development of hypertensive complications in oocyte donation pregnancy: protocol for a systematic review and individual participant data meta-analysis (DONOR IPD)

INTRODUCTION

The assisted reproductive technique of oocyte donation (OD) is comparable to in vitro fertilisation (IVF), with the distinction of using a donated oocyte and thus involving two women. Compared with IVF and naturally conceived (NC) pregnancies, OD pregnancies have a higher risk for pregnancy complications as pregnancy-induced hypertension (PIH) and pre-eclampsia (PE). Various covariates among women pregnant by OD, however, also contribute to an increased risk for developing hypertensive complications. Therefore, we will conduct the DONation of Oocytes in Reproduction individual participant data (DONOR IPD) meta-analysis to determine the risk for the development of hypertensive complications in OD pregnancy, in comparison to autologous oocyte pregnancy (non-donor IVF/intracytoplasmic sperm injection (ICSI) and NC pregnancy). The DONOR IPD meta-analysis will provide an opportunity to adjust for confounders and perform subgroup analyses. Furthermore, IPD will be used to externally validate a prediction model for the development of PE in OD pregnancy.

METHODS AND ANALYSIS

A systematic literature search will be performed to search for studies that included women pregnant by OD, and documented on hypertensive complications in OD pregnancy. The authors from each study will be asked to collaborate and share IPD. Using the pseudoanonymised combined IPD, we will perform statistical analyses with one-stage and two-stage approaches, subgroup analyses and possibly time-to-event analyses to investigate the risk of developing hypertensive complications in OD pregnancy. Furthermore, we will formally assess a prediction model on its performance in an external validation with the use of IPD.

ETHICS AND DISSEMINATION

Ethical approval and individual patient consent will not be required in most cases since this IPD meta-analysis will use existing pseudoanonymised data from cohort studies. Results will be disseminated through peer-reviewed journals and international conferences.

PROSPERO REGISTRATION NUMBER

CRD42021267908.

Different immunoregulatory components at the decidua basalis of oocyte donation pregnancies

Oocyte donation (OD) pregnancies are characterized by more fetal-maternal human leukocyte antigen (HLA) mismatches compared with naturally conceived (NC) and in vitro fertilization (IVF) pregnancies. The maternal immune system has to cope with greater immunogenetic dissimilarity, but involved immunoregulation remains poorly understood. We examined whether the amount of regulatory T cells (Tregs) and immunoregulatory cytokines in decidua basalis of OD pregnancies differs from NC and IVF pregnancies. The cohort included 25 OD, 11 IVF and 16 NC placentas, maternal peripheral blood, and umbilical cord blood of uncomplicated pregnancies. Placenta slides were stained for FOXP3, IL-10, IL-6, gal-1, TGF-β and Flt-1. Semi-quantitative (FOXP3+ Tregs) and computerized analysis (cytokines) were executed. The blood samples were typed for HLA class I and II to calculate fetal-maternal HLA mismatches. The percentage of Tregs was significantly higher in pregnancies with 4-6 HLA class I mismatches (n = 17), compared to 0-3 mismatches (n = 35; p = 0.04). Cytokine analysis showed significant differences between OD, IVF and NC pregnancies. Flt-1 was significantly lower in pregnancies with 4-6 HLA class I mismatches (p = 0.004), and in pregnancies with 6-10 HLA mismatches in total (p = 0.024). This study suggests that immunoregulation at the fetal-maternal interface in OD pregnancies with more fetal-maternal HLA mismatches is altered.