uNK Cell Density Research Articles

Does non-cavity distorting intramural fibroid affect endometrium around the time of embryo implantation?

The effect of the intramural fibroids not distorting the cavity remains controversial on implantation and pregnancy. The aim of this study was to examine the impact of non-cavity distorting intramural fibroids on endometrium. Fifty-six women with non-cavity distorting intramural fibroid were recruited in this study. Paired endometrial specimens, one from beneath the fibroid (ipsilateral endometrium) and the other from the opposite side of uterine cavity, away from the fibroid (contralateral endometrium) were obtained 7–9 days after the luteinizing hormone surge in a natural cycle. Histological dating, Mucin1 and Glycodelin expression and uterine natural killer (uNK) cell density were compared between the paired samples. The median (IQR) H-score of Mucin1 staining in the ipsilateral luminal epithelium was 210% (142–230%), which was significantly (p < 0.05) higher than that of the contralateral luminal endometrium (157%, IQR 114–176%). There was no significant difference in Mucin1 expression in the glandular epithelium. There was no significant difference in Glycodelin expression in luminal and glandular epithelium, uNK cells density or histological dating results between the paired endometrial samples. In conclusion, it is uncertain whether the altered expression of Mucin1 in luminal epithelium alone may have impact on implantation when other markers are not changed.

Ovarian Stimulation in Mice Resulted in Abnormal Placentation through Its Effects on Proliferation and Cytokine Production of Uterine NK Cells.

Ovarian stimulation is associated with an increased incidence of abnormal placentation. Uterine natural killer (uNK) cells are the major subpopulation of decidual immune cells, which are crucial for placentation. In a previous study, we found that ovarian stimulation impairs uNK cell density on gestation day (GD) 8.5 in mice. However, it was not clear how ovarian stimulation led to a reduction in the density of uNK cells. In this study, we constructed two mouse models, an in vitro mouse embryo transfer model and an estrogen-stimulated mouse model. We used HE and PAS glycogen staining, immunohistochemical techniques, q-PCR, Western blot, and flow cytometry to analyze the mouse decidua and placenta, and the results showed that SO resulted in a fetal weight reduction, abnormal placental morphology, decreased placental vascular density, and abnormal density and function of uNK cells. Our results suggest that ovarian stimulation resulted in aberrant estrogen signaling and may contribute to the disorder of uNK cells caused by ovarian stimulation. Together, these results provide new insights into the mechanisms of aberrant maternal endocrine environments and abnormal placentation.

Individual dynamics of uterine natural killer cells in natural and stimulated cycles monitored using a new endometrial dating method.

It is important to evaluate the dynamics of uterine natural killer (uNK) cells in hormone replacement therapy (HRT) cycles, given their potential role in implantation and the common usage of HRT cycles with in vitro fertilization (IVF). A total of 132 subfertile patients were evaluated during the secretory phase of either natural ovulation (OV) or HRT cycles, with two biopsies taken on approximately days 5 and 10 after ovulation/progesterone administration in a single menstrual cycle. Immunohistochemical Personal Endometrial Maturation Analysis (PEMA) was used to better quantify secretory-phase endometrial development, in combination with subsequent evaluation of uNK cell density. uNK cell density increased rapidly from the early to mid-secretory phase, with mean uNK densities of 113 and 117 per mm2 in first biopsies and 315 and 387 per mm2 in second biopsies for OV and HRT cycles, respectively. After reassessment of endometrial development with PEMA, the first and second biopsies in HRT and OV cycles were histologically dated to developmental ranges between days 15-20 (first biopsy) and days 19-25 (second biopsy). Subfertile women showed variable endometrial development in PEMA assessment, with uNK cell density correlating with the dating results. Overall, comparable levels of uNK cell density were observed in OV and HRT cycles. Importantly, uNK cell density depends on the histological maturation stage, with similar low coefficients of determination. This observation suggests that aberrant uNK cell results more likely reflect displaced endometrial maturation, rather than an intrinsic anomaly in uNK cell trafficking.

Ovarian stimulation reduces fetal growth by dysregulating uterine natural killer cells in mice.

Ovarian stimulation is associated with a higher risk of low birth weight. However, the precise mechanisms by which ovarian stimulation increases the chances of low birth weight remain unclear. In this mouse model study, in vivo developed blastocysts that were not exposed to gonadotropins were transferred into pseudopregnant females that had mated naturally (the control group), pseudopregnant females that had been administered a low dose of ovulation-stimulating hormone (the L-SO group) and pseudopregnant females that had been administered a high dose of ovulation-stimulating hormone (the H-SO group). The embryo implantation rate and fetal weight were significantly lower in the L-SO and H-SO groups than in the control group. The density of Dolichos biflorus agglutinin (DBA)+ uterine natural killer (uNK) cells in the decidua basalis was significantly lower in the L-SO and H-SO groups than in the control group. Ovarian stimulation also downregulated a variety of cytokines related to uNK cells that are involved in placental angiogenesis and trophoblast invasion. Collectively, our findings indicate that ovarian stimulation impairs DBA+ uNK cell density in the decidua basalis, which may downregulate uNK-related cytokine secretion and influence placental angiogenesis and restrict fetal growth in mice.

Association between chronic endometritis and uterine natural killer cell density in women with recurrent miscarriage: clinical implications.

This aim of this study was to determine the association between uterine natural killer (uNK) cell density and chronic endometritis (CE). Endometrial biopsies from 135 women with recurrent miscarriage were obtained precisely 7 days after luteinizing hormone surge in natural cycles. Endometrial sections were immunostained for CD56 for uNK cells and CD138 for plasma cells, respectively. Uterine NK cell counting was performed according to a standardized protocol and results were expressed as percentage of CD56+ cells/ total stromal cells. High uNK cell density was defined as >4.5% and CE was diagnosed when the plasma cell density > 5.15 cells/ 10 mm2 . The uNK cells density in women with CE (median, 5.1%; range, 3.4-8.8%) was significantly (P < 0.05) higher than that of those without CE (median, 3.8%; range, 1.2%-7.3%). The prevalence of high uNK cell density in women with CE (11/29, 37.9%) was significantly (P < 0.05) higher than that of women without CE (8/106, 7.5%). To conclude, there was a significant association between high uNK cell density and CE. In women with high uNK cell density, plasma cell should be examined to determine if the underlying cause is associated with CE.

Endometrial uNK cell counts do not predict successful implantation in an IVF population.

Are uterine natural killer (uNK) cell numbers and their distribution relative to endometrial arterioles altered in women with recurrent implantation failure (RIF) compared to women with embryo implantation success (IS)? uNK cell numbers and their distribution relative to endometrial arterioles are not significantly different in women with RIF compared to women in whom embryo implantation occurs successfully following IVF. uNK cells are regulators of decidual angiogenesis and spiral arteriole remodelling during early pregnancy. Although some studies have shown that uNK cell numbers may be altered in women with RIF, the methods used to measure uNK cell numbers have proven inconsistent, making reproduction of these results difficult. It is unclear, therefore, whether the results reported so far are reproducible. Moreover, it is not known how uNK cell numbers may impact IVF outcomes. Despite the lack of conclusive evidence, uNK cell numbers are often evaluated as a prognostic criterion in women undergoing assisted reproductive procedures. Endometrial pipelle biopsies were collected 6-8days post-LH surge in natural cycles from women with RIF (n = 14), women with IS (n = 11) and women with potential RIF at the time of the study (PRIF; n = 9) from 2013 to 2015. uNK cells (i.e. CD56+ and/or CD16+ phenotypes) and their distribution relative to endometrial arterioles were investigated by standard immunohistochemistry protocols and quantified using Aperio ScanScopeXT images digitized by ImageJ and deconvoluted into binary images for single cell quantification using a Gaussian Blur and Yen algorithm. There was no significant difference in the cell density of CD56+ or CD16+ uNK cells in women with RIF compared to women with IS or PRIF. There was a higher proportion of uNK cells in the distal regions compared to the regions closest to the arterioles in all patient groups. Further, we identified a significant reduction in uNK cell density in women who had a previous pregnancy compared to those who had not, regardless of their current implantation status. Not applicable. Spiral arterioles could not always be accurately identified by digital image analysis; therefore, all endometrial arterioles were selected and analysed. Patient numbers for the study were low. However, as the clinical phenotypes of each patient were well defined, and endometrial dating was accurately determined by three independent pathologists, differences between patient groups with respect to the uNK numbers and distribution should have been measurable if uNK cell counts were to be useful as a prognostic marker of RIF. Our findings demonstrate that CD56+ and CD16+ uNK cell numbers are not significantly different in women with RIF in a typical cohort of women undergoing IVF. Further, prior pregnancy was associated with a significantly reduced number of uNK cells in both the RIF and IS patient groups, suggestive of a long-term pregnancy induced suppression of uNK cells. Combined, these findings do not support the clinical value of using uNK cell numbers as a prognostic indicator of implantation success with IVF treatment. Funding for this work was provided by Royal Women's Hospital Foundation. P.P. was supported by an NHMRC Early Career Fellowship [TF 11/14] and W.T.T. was supported by an NHMRC Postgraduate Scholarship [1055814]. The authors do not have any competing interests with this study.

P94: The effect of endometrial scratching and dexamethasone intrauterine infusion for repeated implantation failure patients with different uNK cell density

American Journal of Reproductive ImmunologyVolume 81, Issue S1 p. 81-81 ABSTRACTS P94: The effect of endometrial scratching and dexamethasone intrauterine infusion for repeated implantation failure patients with different uNK cell density First published: 31 May 2019 https://doi.org/10.1111/aji.92_13120Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume81, IssueS1Special Issue: The 39th Annual Meeting of the American Society for Reproductive Immunology, 12-15 June 2019, Grand Rapids, Michigan, USAMay 2019Pages 81-81 RelatedInformation

Dysregulated uterine natural killer cells and vascular remodeling in women with recurrent pregnancy losses.

Angiogenesis and vascular remodeling in secretory endometrium represent one of the crucial steps in pregnancy establishment, for which uterine NK (uNK) cells have an important role. Impairment of these steps may proceed to implantation and instigate initial pathology of recurrent pregnancy losses (RPL). In this study, we aim to investigate vascular development and density of uNK cells in secretory endometrium of women with RPL. Mid-secretory phase endometrial tissues from women with RPL (n=15) and fertile controls (n=7) were investigated. CD56+ and CD16+ uNK cells, CD31+ vascular endothelial cells and smooth muscle myosin (SMM)+ . Vascular smooth muscle cells (VSMC) expressing SMM were investigated using immunohistochemistry and western blot. High-throughput quantitative real-time polymerase chain reaction (qRT-PCR) was used as well. CD56+ uNK number was significantly higher in women with RPL compared to controls (P<0.0001). uNK cell density by immunohistochemistry was positively correlated with CD56 mRNA expression by qRT-PCR (r2 =0.43, P=0.0137). The number of blood vessels represented by the expression of either CD31 or SMM was higher in women with RPL as compared to controls (P<0.05 and P<0.0001, respectively), and correlated with the number of uNK cell (r2 =0.18, P<0.04, and r2 =0.65, P<0.0001, respectively). The wall thickness of spiral arteries was significantly higher in women with RPL as compared with that of controls (P=0.0027). Increased uNK cells in mid-secretory endometrium are associated with increased vascularization and defective vascular transformation of spiral arteries in women with RPL.

Elevated Periimplantation Uterine Natural Killer Cell Density in Human Endometrium Is Associated With Impaired Corticosteroid Signaling in Decidualizing Stromal Cells

Background:Decidualizing human endometrial stromal cells (HESCs) profoundly up-regulate 11β-hydroxysteroid dehydrogenase type 1 (11βHSD1), the enzyme that converts inert cortisone to active cortisol. We postulated that the induction of a cortisol gradient upon decidualization of the periimplantation endometrium may impact on the uterine natural killer (uNK) cell population and on local expression of corticosteroid-dependent target genes.Methods:Midluteal endometrial biopsies (n = 55) were processed for uNK cell (CD56) analysis and primary HESC cultures. The cultures remained either untreated or were decidualized for 4 or 8 days. A tissue microarray was constructed from endometria with normal (n = 18) and elevated uNK cell (n = 18) scores. An abnormal uNK cell test was defined as greater than 5% CD56+ cells in the subluminal stroma.Results:Increased uNK cell density was associated with lower endometrial expression of 11βHSD1 and mineralocorticoid receptor (MR) but not glucocorticoid receptor in vivo. Elevated uNK cell density also corresponded to impaired induction of key decidual markers (11βHSD1, prolactin, and insulin-like growth factor binding protein-1) and MR-dependent enzymes (dehydrogenase/reductase member 3 and retinol saturase) in differentiating HESC cultures. Increased uNK cell density in vivo was not associated with increased in vitro expression of either IL-15 or IL-11, two cytokines implicated in uNK cell regulation.Conclusions:Elevated levels of uNK cells in the stroma underlying the surface epithelium are associated with inadequate cortisol biosynthesis by resident decidualizing cells and suboptimal induction of key MR-dependent enzymes involved in lipid biogenesis and the retinoid transport pathway. Our observations suggest that uNK cell testing identifies those women at risk of reproductive failure due to relative uterine cortisol deficiency.

A feasibility trial of screening women with idiopathic recurrent miscarriage for high uterine natural killer cell density and randomizing to prednisolone or placebo when pregnant

Is it feasible to screen women with idiopathic recurrent miscarriage (RM) for high uterine natural killer (uNK) cell density and then randomize them to prednisolone or placebo when pregnant? It was feasible to recruit women with idiopathic RM into a 'screen and treat' trial despite their desire for active medication. Clinical trials of immunotherapy in women with idiopathic RM have failed to substantiate efficacy in preventing miscarriage. Preimplantation uNK cell density is higher in women with RM and can be reduced with prednisolone. In a pilot RCT, 160 eligible women were screened with an endometrial biopsy and those with high uNK cell density were invited to return when pregnant for randomization to prednisolone (20 mg for 6 weeks, 10 mg for 1 week, 5 mg for 1 week) or identical placebo tablets. Randomization was by random number generation and patients, clinicians and outcome assessors were blinded to allocation. The study size and duration was determined by funding, which was for a feasibility trial, for 2 years, sufficient to screen 150 women and randomize 40 women. The outcome measures were recruitment rate, women's perspectives, compliance, live birth and miscarriage rates and pregnancy complications. The trial was advertised nationally in the UK. Women who attended research clinics run by one consultant (SQ) with three or more consecutive idiopathic miscarriages were included. Women's perspectives of the trial were sought through a questionnaire. The endometrium was sampled 5-9 days after the LH surge, stained using immunohistochemistry for CD56 and the sub-epithelial region analysed with image analysis. Women with a high uNK cell density (>5%) were invited to contact the clinic at 4-6 weeks gestation for randomization. Compliance with medication was assessed using a daily log, and side effects recorded by the women in a diary and on a structured proforma completed in the clinic at the end of the first trimester. All women had ultrasound scans every 2 weeks until 14 weeks' gestation and growth scans at 28 and 34 weeks' gestation in addition to routine antenatal care and a follow-up in person or by telephone 6 weeks after delivery. Despite the fact that 85% of women said they would prefer the active treatment, the trial recruitment occurred at the planned rate. Eligible women (n = 160) attended the research clinics and had the uNK test, 72 were screen positive and 40 returned when pregnant for randomization. Compliance with medication was reported to be 100%. The active treatment was associated with side effects of insomnia and flushing. The live birth rate was 12/20 (60%) with prednisolone and 8/20 (40%) with placebo (Risk Ratio 1.5, 95% confidence interval (CI) 0.79-2.86, absolute difference 20% CI-10%, +50%), and hence, this was not significant. There were no pregnancy complications or serious adverse fetal outcomes. This was a feasibility trial so of insufficient size to assess efficacy or safety. There was inconsistency in the start date of the trial medication and this may have affected the outcome in the active treatment group. It was feasible to recruit women with idiopathic RM into a 'screen and treat' trial despite their desire for active medication. Our data also suggest that in future trials the primary outcome measure is live birth rate after 24 weeks gestation.

A rapid, reliable method for uNK cell density estimation

Interest in uterine NK cell density as a diagnostic or screening tool in reproductive disorders is growing. However, current methods of analysis are time consuming. In this study, 997 images from 100 women were analysed both by the currently used method combining manual and computer aided counting, and by using colour splitting combined with area measurement as an estimate of positively stained cells. Good correlation was found between both methods (r2=0.92) centred around the line of equality, with no systematic differences observed in Bland Altman plots. The area measurement was significantly faster and thus is a useful screening method.

Endometrial cell counts in recurrent miscarriage: a comparison of counting methods

Studies of uterine natural killer (uNK) cells require reliable measurements of uNK cell density among diverse endometrial tissue. The aim of this study was to compare cell counting manually with two computer-aided methods based on a public domain software package, ImageJ. Immunohistochemistry (IHC) of CD56(+) uNK cells was performed on endometrium from recurrent miscarriage patients. Numbers of stromal cells per high-power field (HPF) were counted by two observers using: (i) manual tally counter and graticule; (ii) ImageJ 'point picker' tool; and (iii) ImageJ 'particle analysis' tool. Coefficients of variation (CV) and Bland-Altman plots were used to evaluate interobserver differences. Evaluation of %uNK using ImageJ particle analysis for stromal cell counts and point picker tool for uNK counts was undertaken. Point picker and particle analysis were significantly better than manual counting [interobserver CVs mean (standard deviation) 6.1% (3.3%); 4.7% (3.9%), 8.2% (6.5%), respectively]. Mean inter- and intra-observer CVs for %uNK were 10.3% (6.6%), 8.5% (4.9%) and 6.8% (4.3%), respectively. Bland-Altman analysis revealed no systematic differences in cell counts with the number of cells in the image for each method. Compared to manual cell counting, computer-aided image analysis yields more reproducible results for the assessment of uNK cells density using IHC.

Natural killer cells and pregnancy outcomes in women with recurrent miscarriage and infertility: a systematic review

Peripheral natural killer (pNK) and uterine NK (uNK) cells have been associated with reproductive failure. We systematically reviewed the literature to assess whether numbers or activity of pNK or uNK cells predicted subsequent pregnancy and outcome. We searched the electronic MEDLINE database from 1950 to April 2010 for relevant publications by using MeSH terms 'natural killer cells', 'reproduction' and 'pregnancy complications'. We included studies that measured pre-pregnancy pNK and uNK cell numbers or activity in women with recurrent miscarriage (RM) or infertility, and reported subsequent pregnancy outcomes of miscarriage or failure to conceive after assisted reproductive technology (ART). The search identified 783 publications and 12 fulfilled the inclusion criteria. There were too few women entered into the observational studies to assess whether high pNK cell percentages or activity predicted subsequent miscarriage in women with idiopathic RM (numbers: n = 32, OR 17, 95% CI 0.82-350.6, activity: n = 92, OR 2.51, 95% CI 0.16-40.29), or implantation failure (n = 203, OR 1.35, 95% CI 0.28-6.46), or miscarriage in infertile women after ART (n = 79, OR 2.48, 95% CI 0.50-12.32). Similarly, the studies of uNK cells were not large enough to assess whether abnormal uNK cell density predicted subsequent miscarriage in women with idiopathic RM (n = 72, OR 1.33, 95% CI 0.16-11.11). None of the uNK cell studies in women with infertility reported pregnancy outcomes dichotomized for uNK cell numbers. The prognostic value of measuring pNK or uNK cell parameters remains uncertain. More studies are needed to confirm or refute the role of NK cell assessments as a predictive test for screening women who may benefit from immunotherapy.

SELECTED ORAL COMMUNICATION SESSION, SESSION 34: EARLY PREGNANCY LOSS PROGNOSIS AND TREATMENT, Tuesday 5 July 2011 10:00 - 11:30

Introduction: Multiple trials of immunotherapy for reproductive failure have failed to demonstrate significant benefit. A reason for this may be the lack of a test that selects which women will benefit from treatment. High density of uterine naturak killer (uNK) cells has been associated with recurrent miscarriage (RM) and prednisolone was shown to reduce this uNK cell density. Hence we carried out a double blind randomised placebo controlled trial of prednisolone versus placebo in early pregnancy for women with RM and increased uNK cell density. The aim of this pilot trial was to assess the feasibility of recruitment, integrity of trial procedures and potential efficacy for future power calculations.

Uterine natural killer cells and angiogenesis in recurrent reproductive failure

Increased numbers of phenotypically unusual CD56(bright) CD16- uterine natural killer (uNK) cells have been associated with recurrent reproductive failure. uNK cells produce angiogenic growth factors and are potential regulators of decidual angiogenesis in early pregnancy. The final common mechanism for early pregnancy loss is thought to be early onset of the maternal circulation and excessive placental oxidative stress. We tested the hypothesis that increased uNK cells in preimplantation endometrium are associated with altered angiogenesis. Women with recurrent reproductive failure (n = 122) were investigated with uterine artery Doppler and endometrial biopsy. Immunohistochemistry was used to identify uNK, endothelial and vascular smooth muscle cells and image analysis was used to assess location, density and differentiation. uNK cell density was positively correlated with the formation of blood (P = 0.005, r = 0.5) and lymphatic vessels (P = 0.0001, r = 0.6), spiral arteriole smooth muscle differentiation (P = 0.01, r = 0.5) and endometrial oedema (P = 0.004). The functional effect of this was a reduced uterine artery resistance to blood flow. These data suggest that uNK cells may regulate angiogenesis in non-pregnant endometrium. The mechanisms of reproductive failure associated with increased uNK cell density appear to be increased angiogenesis and peri-implantation blood flow, which may lead to early maternal circulation and hence pregnancy failure due to excessive oxidative stress.

286. The role of uterine natural killer cells in causing irregular bleeding in HT users

Menopausal hormone therapy (HT) causes irregular bleeding in up to 60% of user. This is extremely unpopular with patients, and commonly leads to invasive and expensive investigations to rule out underlying pelvic pathology. In most cases no cause is found. The aim of this study was to further elucidate the mechanisms of vascular fragility. Uterine NK cells are known to increase vascular fragility during the normal menstrual cycle. We hypothesise that HT is associated with an increase in uterine natural killer (uNK) cells. Eighty six endometrial biopsies were obtained from 59 postmenopausal users of continuous combined HT. Uterine NK cells were identified using immunohistochemistry as being CD56+. Image analysis was used to identify absolute number of CD56+ cells and their distribution within the stroma. Endometrial histology was classified using Noyes criteria. A statistically significant increase in endometrial uNK cell density was observed in HT users compared to postmenopausal women not using HT (P &lt; 0.001). uNK cell populations were more marked in biopsies taken during a bleeding episode compared to those HT users with amenorrhoea (P = 031). uNK cells are a major regulator of endometrial vascular integrity and are known to be disrupted in irregular bleeding with progestin only contraceptives. This is the first study to report the presence of uNK cells in postmenopausal endometrium and the first to report a significant association between bleeding patterns and uNK cell density. We postulate that HT induces an increase in endometrial uNK cell populations and that their presence stimulates endometrial vascular fragility leading to bleeding.