Correlation of peripheral blood and endometrial immunophenotyping in ART: is peripheral blood sampling useful?

PURPOSE

Using a comprehensive flow cytometric panel, simultaneously obtained mid-luteal immunophenotypes from peripheral blood and endometrium were compared and values correlated. Is a peripheral blood evaluation of reproductive immunophenotype status meritorious relative to local endometrial evaluation to directly assess the peri-implantation environment?

METHODS

Fifty-five patients had a mid-luteal biopsy to assess the local endometrial immunophenotype, while simultaneously providing a peripheral blood sample for analysis. Both samples were immediately assessed using a comprehensive multi-parameter panel, and lymphocyte subpopulations were described and compared.

RESULTS

Distinct lymphocyte proportions and percentage differences were noted across the two compartments, confirming the hypothesis that they are distinct environments. The ratio of CD4 + to CD8 + T cells were reversed between the two compartments, as were Th1 and Th2-type CD4 + T cell ratios. Despite these differences, some direct relationships were noted. Positive Pearson correlations were found between the levels of CD57 + expressing natural killer cells, CD3 + NK-T cells and CD4 + Th1 cells in both compartments.

CONCLUSIONS

Flow cytometric evaluation provides a rapid and objective analysis of lymphocyte subpopulations. Endometrial biopsies have become the gold standard technique to assess the uterine immunophenotype in adverse reproductive outcome, but there may still a place for peripheral blood evaluation in this context. The findings demonstrate significant variations in cellular proportions across the two regions, but some positive correlations are present. Immunological assessment of these specific peripheral blood lymphocyte subtypes may provide insight into patients with potential alterations of the uterine immune environment, without the risks and inconveniences associated with an invasive procedure.

Potential utility of a non-invasive menstrual blood immunophenotype analysis in reproductive medicine

Purpose Can a comprehensive flow cytometry panel be used to assess immunophenotype profiles in menstrual blood of patients experiencing reproductive failure and age matched controls of proven fertility? Methods 58 recurrent pregnancy loss and repeated implantation failure patients, along with 15 age matched controls of proven fertility, had menstrual blood samples obtained within the first 24 hours of the onset of menstruation to non-invasively assess the local immunophenotype. Using a comprehensive multi-parameter flow panel the lymphocyte sub-populations were described and compared. Results Relative to well established peripheral blood immunophenotyping values, distinct lymphocyte population differences were noted between the subgroups. The ratios of CD4+ and CD8+ T-cells were inverted relative to peripheral blood and uterine NK cells represented by CD56bright were distinctly visualised, emphasising the distinction of menstrual and peripheral blood. Relative to controls there were marked increases in CD3+ve T-cells (p=0.009), CD4:CD8 ratio (p=0.004), CD19 B-cells (p=0.026) and CD56dim NK's (p=0.002) in the reproductive failure cases. Conclusions Flow cytometric evaluation can provide a rapid and objective analysis of lymphocyte subpopulations in many forms of tissue and fluid. The findings show significant variations in cellular composition of immune cells indicating a distinct compartment, with differences between cases and controls. Immunological assessment of the menstrual blood immunophenotype, in clinically appropriate patients, may provide insight into the aetiology of adverse reproductive outcome, without the risks and inconveniences associated with a more invasive endometrial biopsy.

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.

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.

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.

Anti-oxidant mediated normalisation of raised intracellular cytokines in patients with reproductive failure

Background

Raised intracellular cytokine ratios (CKR) are proposed as a significant risk factor for adverse reproductive outcome. An elevated cytokine ratio, such as between TNFa and/or IFNg to IL-10 is associated with recurrent miscarriage (RM). The use of pharmacological immunomodulators such as TNFα inhibitors in these patients is controversial and not generally recommended due to a lack of conclusive data supporting their use. We evaluated whether the use of anti-oxidants/dietary supplements as an alternative could positively influence CKR’s in ART patients.

Methods

A prospective non-placebo control trial of antioxidant treatment for abnormal peripheral inflammatory cytokine ratios was performed. CKRs were assessed using flow cytometry in stimulated versus unstimulated whole blood samples in 337 IVF patients presenting with a previous history of poor outcome (RM or implantation failure). CKR’s were found to be elevated in 150/337. 70/150 patients in this elevated group agreed to a 10 week regime of Omega 3, vitamin D3, and B complex, followed by retesting to evaluate effect.

Results

Mean cytokine ratios significantly improved between tests. Pre-treatment TNFa:IL-10 ratio improved from 71.6 to 21.0 (p < 0.0001) and IFNg:IL-10 ratio dropped from 24.5 to 12.5 (p < 0.0001). The improved ratios were achieved primarily by an increase in IL-10 expression (P = 0.0007), but also by a moderate decrease in stimulated TNFa expression (p = 0.008). Mean IFNg expression was unchanged (p = 0.42). On an individual basis CKR levels were normalised in 43 patients, improved in 12 and remained unchanged in 15. No significant differences in improvement were found between RM and IF subgroups.

Conclusions

Intracellular cytokine expression levels and ratios were modifiable by the supplement regime employed. Elevated cytokine ratios have been linked with adverse reproductive outcomes, and proposed treatments have included biological immunomodulators which antagonise TNFa, but come with significant associated cost implications and more importantly, cytotoxic side-effects. A dietary regime is more patient friendly and lower risk, while still achieving a similar effect in many patients.

Revisiting the Functional Impact of NK Cells

Immune responses are critical for the maintenance of homeostasis but can also upset the equilibrium, depending on the context and magnitude of the response. Natural killer (NK) cells are well known for their important roles in antiviral and antitumor immune responses, and they are currently used, mostly under optimized forms, as immunotherapeutic agents against cancer. Nevertheless, with accumulating examples of deleterious effects of NK cells, it is paramount to consider their negative contributions. Here, we critically review and comment on the literature surrounding undesirable aspects of NK cell activity, focusing on situations where they play a harmful rather than a protective role.

Why natural killer cells are not enough: a further understanding of killer immunoglobulin-like receptor and human leukocyte antigen

The immune system's role in recurrent reproductive failure is a controversial issue in assisted reproduction. Most studies into immune system implication in reproduction have focused on finding markers of peripheral blood and less on the uterine environment. Peripheral blood natural killer cells have become an "immune study core" for women with recurrent miscarriage or recurrent implantation failure, based on the mistaken notion that they cause reproductive failure by killing or "rejecting" the embryo. Maternal-fetal tolerance begins at the uterine level, so successful adaptation to the fetus occurs after a complicated process. Insufficient uterine lining invasion by an invading extravillous trophoblast is the primary defect in pregnancy disorders such as recurrent miscarriage. This process is regulated by the interaction between maternal killer immunoglobulin-like receptors (KIRs), expressed by uterine natural killer cells (uNK), and their ligand human leukocyte antigen (HLA) C, expressed by the extravillous trophoblast. Pregnancies are an increased risk of disorders in mothers with KIR AA when the fetus has paternal HLA-C2. A recent report has indicated that the expression of more than one paternal HLA-C by the extravillous trophoblast in assisted reproduction may affect placentation in mothers with KIR AA. This review provides insight into the immune system's role in assisted reproductive treatments. These insights can have an impact on the selection of single-embryo transfer and/or oocyte/sperm donor according to HLA-C in patients with recurrent implantation failure and recurrent miscarriage depending on their KIR haplotype.