Contribution of immunology to implantation failure of euploid embryos

Cytometric assessment of uterine receptivity via epithelial β3 integrin expression

RESEARCH QUESTION

Many techniques now exist to assess the receptivity status of the endometrium. Can a simple low-cost flow cytometric technique be used to rapidly assess uterine receptivity via a luteal phase endometrial biopsy?

DESIGN

Epithelial β3 integrin (EB3) evaluation was undertaken in 300 women presenting with repeated implantation failure or recurrent pregnancy loss who subsequently underwent 710 assisted reproductive technology (ART) cycles. Endometrial tissue was mechanically dissociated and evaluated using specific antibodies to capture integrin expression. Autologous and donor oocyte embryo transfers were evaluated. A 'High', 'Borderline' and 'Low' grading system was developed based on the pattern and percentage expression of EB3 relative to the total endometrial epithelium. Clinical outcomes of the resulting embryo transfers (n = 559) were analysed according to EB3 grading.

RESULTS

Based on 180 completed transfers, the clinical pregnancy rate (CPR) per embryo transferred in the donor egg cycles was 41.7%. EB3 results from women with a 'High' grading showed a superior CPR (54.0%) compared with 'Low' (22.2% CPR) or 'Borderline' (37.4%) cases (P = 0.024). Similarly, following 379 autologous oocyte transfers, the CPR was 36.1% overall, with major variations between the 'High' (43.8%), 'Low' (17.5%) and 'Borderline' (34.8%) groups (P = 0.0008). Implantation rates showed similar significant trends in the 'High' versus 'Low' groups of 40.4% versus 16% (P = 0.048) in donor oocyte transfers, and 30.8% versus 16.1% (P = 0.025) in autologous oocyte transfers.

CONCLUSIONS

The distribution patterns and percentage expression of EB3 assessed by a flow cytometry grading system shows a significant relationship to implantation rate and CPR success in ART cycles and may thus represent a useful additional tool for the assessment of uterine receptivity.

Endometrial lymphocyte concentrations in adverse reproductive outcome populations

PURPOSE

The uterine immunophenotype is relatively poorly understood, with most studies reporting proportions/percentages. A novel technique to calculate local endometrial lymphocyte concentrations is described, and used to compare results between aetiological subgroups such as repeated implantation failure (RIF) and recurrent pregnancy loss (RPL) with male-factor controls.

METHODS

455 patients had an endometrial biopsy performed. Background history on initial presentation was used to subdivide the population into RIF (n = 149), RPL (n = 121), primary (n = 76) and secondary infertility (n = 80). A control group was identified comprising male factor infertility aetiology with all female investigations normal (n = 29). Endometrial Tissue was assessed using a comprehensive multi-parameter panel. Lymphocyte subpopulations were calculated using flowcount flurospheres and a mathematical correction applied to determine concentrations per milligram of tissue, based on original biopsy weight and volumetric dilutions.

RESULTS

The flow cytometry technique was successful in determining population centiles for concentrations of endometrial lymphocyte subsets. Distinct differences were noted across the patient groups. Th2 concentrations were significantly higher in the controls (p = 0.0002). All RPL/infertile populations had increased concentrations of peripheral type NK's (p = 0.016) and B cells (p = 0.045). Relative to male factor controls, CD4+ and CD8+ T lymphocyte populations were increased in RPL patients, and reduced in those with a history of RIF. Th1 concentrations were elevated in the adverse outcome groups (p = 0.032). Concentration centiles alone do not appear to accurately predict outcome with subsequent treatment.

CONCLUSIONS

Endometrial biopsy analysis by flow cytometry can provide detailed analysis of constituent lymphocyte subsets by concentration as well as proportion. This novel approach provides additional independent data to further assess the significance of endometrial changes in the setting of reproductive failure.

Exposure to Titanium Dioxide Nanoparticles During Pregnancy Changed Maternal Gut Microbiota and Increased Blood Glucose of Rat

Titanium dioxide nanoparticles (TiO₂ NPs) were used worldwide for decades, and pregnant women are unable to avoid exposing to them. Studies revealed that TiO₂ NPs could kill many kinds of bacteria, but whether they would affect the composition of gut microbiota, especially during pregnancy, was seldom reported. And, what adverse effects may be brought to pregnant females was also unknown. In this study, we established the prenatal exposure model of rats to explore the effects of TiO₂ NPs on gut microbiota. We observed an increasing trend, but not a significant change of alpha-diversity among control and exposure groups at gestation day (GD) 10 and GD 17 during normal pregnancy process. Each different time point had unique gut microbiota operational taxonomic units (OTUs) characteristics. The abundance of Ellin6075 decreased at GD 10 and GD 17, Clostridiales increased at GD 10, and Dehalobacteriaceae decreased at GD 17 after TiO₂ NPs exposure. Further phylogenetic investigation of communities by reconstruction of unobserved states (PICRUSt) prediction indicated that the type 2 diabetes mellitus related genes were enhanced, and taurine metabolism was weakened at the second-trimester. Further study showed that the rats' fasting blood glucose levels significantly increased at GD 10 (P < 0.05) and GD 17 (P < 0.01) after exposure. Our study pointed out that TiO₂ NPs induced the alteration of gut microbiota during pregnancy and increased the fasting blood glucose of pregnant rats, which might increase the potential risk of gestational diabetes of pregnant women.

Therapeutic role of granulocyte colony-stimulating factor (G-CSF) for infertile women under in vitro fertilization and embryo transfer (IVF-ET) treatment: a meta-analysis

OBJECTIVE

The aim of this meta-analysis is to explore the beneficial role of granulocyte colony-stimulating factor (G-CSF) on infertile women under artificial reproduction technology treatment.

METHOD

Medline, Embase and ISI Web of Science databases were searched to identify relevant randomized control trials. Studies before July, 2017 were included for primary screening. Meta-analysis of the total and subgroup patients was conducted, and relative risks (RRs) and their 95% confidence intervals (95% CI) were calculated by a fixed-effect model if no heterogeneity (evaluated as I2 statistic) existed. Otherwise, a random-effects model was adopted. Subgroup analysis was performed by administrating route or clinical indication. Egger test and influence analysis were conducted to evaluate the publication bias and study power, respectively.

RESULTS

The final selection enrolled 10 RCTs, involving 1016 IVF-ET cycles (521 distributed to the G-CSF group and 495 to the control). Compared with control group, G-CSF administration could significantly improve clinical pregnancy rate (CPR, RR 1.89, 95% CI 1.53-2.33), while it had no beneficial effect on embryo implantation rate (IR, RR 1.84, 95% CI 0.84-4.03). The subgroup analysis by administration route showed that both uterine infusion and subcutaneous injection can produce a substantial increase in CPR, with the pooled RRs (95% CI) 1.46 (1.04-2.05) and 2.23 (1.68-2.95), respectively. Nevertheless, most of included RCTs dealt with the RIF subjects, and the pooled analysis of this data showed a higher PR and IR in G-CSF group as compared to that in the control, with the RRs (95% CI) 2.07 (1.64-2.61) and 1.52 (1.08-2.14), respectively. Egger regression test did not demonstrate any significance for the publication bias.

CONCLUSION

G-CSF administration has a beneficial role on the clinical outcome after embryo transfer by both routes of local infusion and systematic administration, especially for the cases with RIF. Further RCTs are needed to investigate the role of G-CSF in thin endometrium patients.

Detailed endometrial immune assessment of both normal and adverse reproductive outcome populations

PURPOSE

Using a comprehensive flow cytometric panel, do endometrial immune profiles in adverse reproductive outcomes such as repeat implantation failure (RIF) and repeat pregnancy loss (RPL) differ from each other and male-factor controls?

METHODS

Six-hundred and twelve patients had an endometrial biopsy to assess the immunophenotype. History on presentation was used to subdivide the population into recurrent implantation failure (RIF) [n = 178], recurrent pregnancy loss (RPL) [n = 155], primary infertility [n = 130] and secondary infertility [n = 114]. A control group was utilised for comparative purposes [n = 35] and lymphocyte subpopulations were described.

RESULTS

Distinct lymphocyte percentage differences were noted across the populations. Relative to controls and RPL, patients with a history of RIF had significantly raised uterine NKs (53.2 vs 45.2 & 42.9%, p < 0.0001). All sub-fertile populations had increased percentage peripheral type NKs (p = 0.001), and exhibited increased CD69+ activation (p = 0.005), higher levels of B cells (p < 0.001), elevated CD4:CD8 ratio (p < 0.0001), lower T-regs (p = 0.034) and a higher proportion of Th1+ CD4s (p = 0.001). Patient aetiology confers some distinct findings, RPL; pNK, Bcells and CD4 elevated; RIF; uNK and CD56 raised while CD-8 and NK-T lowered.

CONCLUSIONS

Flow cytometric endometrial evaluation has the ability to provide a rapid and objective analysis of lymphocyte subpopulations. The findings show significant variations in cellular proportions of immune cells across the patient categories relative to control tissue. The cell types involved suggest that a potential differential pro-inflammatory bias may exist in patients with a history of adverse reproductive outcomes. Immunological assessment in appropriate populations may provide insight into the underlying aetiology of some cases of reproductive failure.

Increased levels of CCR7(lo)PD-1(hi) CXCR5+ CD4+ T cells, and associated factors Bcl-6, CXCR5, IL-21 and IL-6 contribute to repeated implantation failure

In vitro fertilization-embryo transfer (IVF-ET) can be used by infertile couples to assist with reproduction; however, failure of the embryo to implant into the endometrial lining results in failure of the IVF treatment. The present study investigated the expression of chemokine receptor 7 (CCR7)(lo) programmed death-1(PD-1)(hi) chemokine receptor type 5 (CXCR5)⁺ cluster of differentiation 4 (CD4)⁺ T cells and associated factors in patients with repeated implantation failure (RIF). A total of 30 females with RIF and 30 healthy females were enrolled in the current study. Flow cytometry was used to detect the proportion of CCR7(lo)PD-1(hi) CXCR5⁺ CD4⁺ T cells in the peripheral blood. Cytokine bead arrays were performed to detect the levels of interleukin (IL)-6, −4 and −2 in the serum. ELISAs were used to detect the level of IL-21 in the serum. Quantitative real time polymerase chain reaction analysis and immunohistochemistry were used to investigate the expression of B-cell lymphoma 6 (Bcl-6), chemokine receptor type 5 (CXCR5) and IL-21 in the endometrium. The results revealed that the percentage of CCR7(lo)PD-1(hi) CXCR5⁺ CD4⁺ T cells was increased in the RIF group compared with the control group during the mid luteal phase. The mRNA and protein levels of Bcl-6, IL-21 and CXCR5 in the endometrium and the concentrations of IL-21 and IL-6 in the serum were significantly increased in the RIF group; however, no significant difference was observed between the two groups in regards to the expression of IL-4 and IL-2. Furthermore, a significant positive correlation was identified between the percentage of CCR7(lo)PD-1(hi) CXCR5⁺ CD4⁺ T cells and IL-21 and IL-6 levels. The expression of IL-21 also had a positive correlation with Bcl-6 and CXCR5 expression in the RIF group. These results suggest that increased levels of CCR7(lo)PD-1(hi) CXCR5⁺ CD4⁺ T cells and associated factors contribute to RIF and could therefore be a potential therapeutic target.