Abstract
STUDY QUESTION
Are genetic effects on endometrial gene expression tissue specific and/or associated with reproductive traits and diseases?
SUMMARY ANSWER
Analyses of RNA-sequence data and ...individual genotype data from the endometrium identified novel and disease associated, genetic mechanisms regulating gene expression in the endometrium and showed evidence that these mechanisms are shared across biologically similar tissues.
WHAT IS KNOWN ALREADY
The endometrium is a complex tissue vital for female reproduction and is a hypothesized source of cells initiating endometriosis. Understanding genetic regulation specific to, and shared between, tissue types can aid the identification of genes involved in complex genetic diseases.
STUDY DESIGN, SIZE, DURATION
RNA-sequence and genotype data from 206 individuals was analysed and results were compared with large publicly available datasets.
PARTICIPANTS/MATERIALS, SETTING, METHODS
RNA-sequencing and genotype data from 206 endometrial samples was used to identify the influence of genetic variants on gene expression, via expression quantitative trait loci (eQTL) analysis and to compare these endometrial eQTLs with those in other tissues. To investigate the association between endometrial gene expression regulation and reproductive traits and diseases, we conducted a tissue enrichment analysis, transcriptome-wide association study (TWAS) and summary data-based Mendelian randomisation (SMR) analyses. Transcriptomic data was used to test differential gene expression between women with and without endometriosis.
MAIN RESULTS AND THE ROLE OF CHANCE
A tissue enrichment analysis with endometriosis genome-wide association study summary statistics showed that genes surrounding endometriosis risk loci were significantly enriched in reproductive tissues. A total of 444 sentinel cis-eQTLs (P < 2.57 × 10−9) and 30 trans-eQTLs (P < 4.65 × 10−13) were detected, including 327 novel cis-eQTLs in endometrium. A large proportion (85%) of endometrial eQTLs are present in other tissues. Genetic effects on endometrial gene expression were highly correlated with the genetic effects on reproductive (e.g. uterus, ovary) and digestive tissues (e.g. salivary gland, stomach), supporting a shared genetic regulation of gene expression in biologically similar tissues. The TWAS analysis indicated that gene expression at 39 loci is associated with endometriosis, including five known endometriosis risk loci. SMR analyses identified potential target genes pleiotropically or causally associated with reproductive traits and diseases including endometriosis. However, without taking account of genetic variants, a direct comparison between women with and without endometriosis showed no significant difference in endometrial gene expression.
LARGE SCALE DATA
The eQTL dataset generated in this study is available at http://reproductivegenomics.com.au/shiny/endo_eqtl_rna/. Additional datasets supporting the conclusions of this article are included within the article and the supplementary information files, or are available on reasonable request.
LIMITATIONS, REASONS FOR CAUTION
Data are derived from fresh tissue samples and expression levels are an average of expression from different cell types within the endometrium. Subtle cell-specifc expression changes may not be detected and differences in cell composition between samples and across the menstrual cycle will contribute to sample variability. Power to detect tissue specific eQTLs and differences between women with and without endometriosis was limited by the sample size in this study. The statistical approaches used in this study identify the likely gene targets for specific genetic risk factors, but not the functional mechanism by which changes in gene expression may influence disease risk.
WIDER IMPLICATIONS OF THE FINDINGS
Our results identify novel genetic variants that regulate gene expression in endometrium and the majority of these are shared across tissues. This allows analysis with large publicly available datasets to identify targets for female reproductive traits and diseases. Much larger studies will be required to identify genetic regulation of gene expression that will be specific to endometrium.
STUDY FUNDING/COMPETING INTEREST(S)
This work was supported by the National Health and Medical Research Council (NHMRC) under project grants GNT1026033, GNT1049472, GNT1046880, GNT1050208, GNT1105321, GNT1083405 and GNT1107258. G.W.M is supported by a NHMRC Fellowship (GNT1078399). J.Y is supported by an ARC Fellowship (FT180100186). There are no competing interests.
ABSTRACT
Endometriosis is a heterogeneous disease in terms of patient symptoms, treatment responsiveness and the presentation of endometriotic lesions. This article explores the histological features ...of endometriotic lesions, highlighting their sometimes underappreciated heterogeneity. We note the variability in evidence for and against the menstrual cycle responsiveness of lesions and consider the utility of drawing parallels between endometriotic lesions and eutopic endometrium. We ask whether histopathologic features beyond just the presence/absence of endometrial-like glands and/or stroma could help improve disease stratification. At the same time, we acknowledge the desire of many clinicians and patients to avoid invasive surgery thereby limiting the ability to histologically phenotype lesions. The ability to derive clinically useful histological information from endometriotic lesions, in association with patient data, would be invaluable to clinicians to help improve treatment options in such a diverse group of patients. However, in suggesting that a shift in focus may enable the development of a better patient stratification system, we recognise that our wish for a single comprehensive stratification system may be beyond reach for a disease of such diverse presentation.
Is the expression of steroid hormone receptors (oestrogen receptor-α and progesterone receptor A/B) and proliferative markers (Bcl-2 and Ki67) uniform among superficial peritoneal endometriotic ...lesions?
A retrospective cohort study of 24 patients with surgically and histologically confirmed endometriosis. Immunofluorescence was used to determine the proportion of oestrogen receptor-α (ERα), progesterone receptor A/B, Bcl-2 and Ki67 positive cells in 271 endometriotic lesions (defined as endometriotic gland profile/s within an individual region of CD10 stromal immunostaining from a single biopsy) from 67 endometriotic biopsies from 24 patients. Data were analysed to examine associations related to menstrual cycle stage, lesion location and gland morphology.
Oestrogen receptor-α and progesterone receptor A/B expression in superficial peritoneal endometriotic lesions was extremely heterogeneous. Bcl-2 immunostaining in endometriotic lesions was also variable, whereas Ki67 immunostaining was minimal. Menstrual cycle stage associations were limited in steroid hormone receptor and Bcl-2 expression in lesions. Patterns in progesterone receptor A/B and Bcl-2 immunostaining were associated with lesion location. Bcl-2 was differentially expressed, based on lesion gland morphology.
These data demonstrate considerable diversity in the expression of steroid hormone receptors and Bcl-2 between lesions, even within an individual patient.
Introduction
Endometriosis is an under‐researched disease, with Aotearoa‐specific data severely lacking. Current estimates of parameters such as rates of endometriosis diagnosis, indication for ...surgery and sites of disease are based on international data. There is currently no published data on endometriosis surgeries in Aotearoa New Zealand.
Aims
We aimed to describe the laparoscopic surgeries conducted for suspected endometriosis at Te Whatu Ora – Capital and Coast, including the prevalence of endometriosis in this cohort, indication for surgery, symptoms experienced, endometriosis stage and sites involved, number of repeat laparoscopies, and prevalence of endometriosis at repeat surgery.
Materials and methods
To conduct this retrospective cross‐sectional study, data were extracted from Te Whatu Ora – Capital and Coast systems to identify all records indicating surgery for suspected endometriosis during 2018 and 2019. Variables investigated included age, ethnicity, endometriosis diagnosis (International Classification of Diseases‐10 Clinical Modification coding), stage of endometriosis, histological report and endometriosis symptoms (pain and/or fertility).
Results
There were 436 surgeries for suspected endometriosis performed during 2018 and 2019, and endometriosis was diagnosed in 68.3% of these surgeries. Pacific and Asian people were under‐represented in the study cohort compared to the demographics of the hospital catchment area (Pacific: 3.0% vs 8.4%, Asian: 9.9% vs 12.9%). The most common indication for surgery was pain. There were 76 surgeries performed for suspected recurrence of endometriosis, and endometriosis was identified in 55.6% of these.
Conclusions
Endometriosis surgeries in this hospital in Aotearoa show similar presentations and surgical findings to international data. Our findings highlight areas requiring more research in an Aotearoa‐specific context.
Pacific young people living in Aotearoa New Zealand experience disparities in their sexual and reproductive health outcomes, thought to stem from cultural differences and educational inequities. ...Although these barriers have been characterised in literature, their influence on Pacific youth’s understandings of sexual and reproductive health have been relatively unexplored. This study investigated the sexual and reproductive health knowledge of Pacific students enrolled at a university in Aotearoa New Zealand in 2020 and where they gained this knowledge. The study used the theoretical framework of the (revitalised) Fonofale health model and was guided by the Kakala research methodology. Data were collected by means of an online survey comprised of open-ended questions and Likert scales, completed by eighty-one eligible students. Open-ended questions were analysed for general themes and responses to Likert scale items are reported using descriptive statistical analysis. The study found that Pacific youth have strong foundations of health knowledge that is heavily influenced by Polynesian cultural beliefs. Both formal and non-formal learning environments were important in developing participants’ health knowledge of these topics and for encouraging independent help-seeking behaviours. This is the first reported study to investigate the sexual and reproductive health knowledges of a pan-Pacific tertiary cohort of young people.
Despite surgical and pharmacological interventions, endometriosis can recur. Reliable information regarding risk of recurrence following a first diagnosis is scant. The aim of this study was to ...examine clinical and survey data in the setting of disease recurrence to identify predictors of risk of endometriosis recurrence.BACKGROUNDDespite surgical and pharmacological interventions, endometriosis can recur. Reliable information regarding risk of recurrence following a first diagnosis is scant. The aim of this study was to examine clinical and survey data in the setting of disease recurrence to identify predictors of risk of endometriosis recurrence.This observational study reviewed data from 794 patients having surgery for pelvic pain or endometriosis. Patients were stratified into two analytic groups based on self-reported or surgically confirmed recurrent endometriosis. Statistical analyses included univariate, followed by multivariate logistic regression to identify risk factors of recurrence, with least absolute shrinkage and selection operator (Lasso) regularisation. Risk-calibrated Supersparse Linear Integer Models (RiskSLIM) and survival analyses (with Lasso) were undertaken to identify predictive features of recurrence.METHODSThis observational study reviewed data from 794 patients having surgery for pelvic pain or endometriosis. Patients were stratified into two analytic groups based on self-reported or surgically confirmed recurrent endometriosis. Statistical analyses included univariate, followed by multivariate logistic regression to identify risk factors of recurrence, with least absolute shrinkage and selection operator (Lasso) regularisation. Risk-calibrated Supersparse Linear Integer Models (RiskSLIM) and survival analyses (with Lasso) were undertaken to identify predictive features of recurrence.Several significant features were repeatedly identified in association with recurrence, including adhesions, high rASRM score, deep disease, bowel lesions, adenomyosis, emergency room attendance for pelvic pain, younger age at menarche, higher gravidity, high blood pressure and older age. In the surgically confirmed group, with a score of 5, the RiskSLIM method was able to predict the risk of recurrence (compared to a single diagnosis) at 95.3% and included adenomyosis and adhesions in the model. Survival analysis further highlighted bowel lesions, adhesions and adenomyosis.RESULTSSeveral significant features were repeatedly identified in association with recurrence, including adhesions, high rASRM score, deep disease, bowel lesions, adenomyosis, emergency room attendance for pelvic pain, younger age at menarche, higher gravidity, high blood pressure and older age. In the surgically confirmed group, with a score of 5, the RiskSLIM method was able to predict the risk of recurrence (compared to a single diagnosis) at 95.3% and included adenomyosis and adhesions in the model. Survival analysis further highlighted bowel lesions, adhesions and adenomyosis.Following an initial diagnosis of endometriosis, clinical decision-making regarding disease management should take into consideration the presence of bowel lesions, adhesions and adenomyosis, which increase the risk of endometriosis recurrence.CONCLUSIONSFollowing an initial diagnosis of endometriosis, clinical decision-making regarding disease management should take into consideration the presence of bowel lesions, adhesions and adenomyosis, which increase the risk of endometriosis recurrence.
Do different subtypes of superficial peritoneal endometriotic lesions exist, based on the presence and morphology of smooth muscle, collagen fibres and immune cell populations?
A retrospective cohort ...study of 24 patients, from across the menstrual cycle, with surgically and histologically confirmed endometriosis. Immunofluorescence was used to delineate the CD10 stromal area of lesions (n = 271 lesions from 67 endometriotic biopsies), and then smooth muscle actin (SMA) positive tissue and immune cell populations (CD45+ and CD68+) were quantified within and adjacent to these lesions. Second harmonic generation microscopy was used to evaluate the presence and morphology of type-1 collagen fibres within and surrounding lesions.
Overall, immune cell numbers and the area of SMA and collagen within endometriotic lesions tended to be low, but a spectrum of presentations significantly varied, particularly in the adjacent tissue microenvironment, based on lesion locations, the morphology of endometriotic gland profiles, or both. Lesions in which collagen fibres formed well aligned capsules around the CD10+ stromal border were identified compared with lesions in which collagen fibre distribution was random. Considerable inter- and intra-patient variability in the morphology of SMA and collagen was observed within and surrounding lesions.
These data demonstrate considerable diversity in the presence of immune cells and morphology of SMA and collagen within, but even more so, surrounding endometriotic lesions, even within individual patients. This heterogeneity, especially within individual patients, presents a challenge to incorporating these cell and tissue types into any new endometriosis classification systems or prognostic approaches.
Endometriosis is a disease defined by the presence of benign lesions of endometrial-like glands and stroma outside the endometrial cavity. Affecting an estimated 11.4% of Australian women, symptoms ...include chronic pelvic pain, dysmenorrhea and infertility. The current gold standard of diagnosis requires an expensive and invasive laparoscopic surgery, resulting in delayed time to treatment. The identification of a non-invasive endometriosis biomarker - a measurable factor correlating with disease presence or activity - has therefore become a priority in endometriosis research, although no biomarker has yet been validated. As small molecule metabolites and lipids have emerged as a potential focus, this review with systematic approach, aims to summarize studies examining metabolomic biomarkers of endometriosis in order to guide future research. EMBASE, PubMed and Web of Science were searched using keywords: lipidomics OR metabolomics OR metabolome AND diagnostic tests OR biomarkers AND endometriosis, and only studies written in English from August 2000 to August 2020 were included. Twenty-nine studies met inclusion and exclusion criteria and were included. These studies identified potential biomarkers in serum, ectopic tissue, eutopic endometrium, peritoneal fluid, follicular fluid, urine, cervical swabs and endometrial fluid. Glycerophospholipids were identified as potential biomarkers in all specimens, except urine and cervical swab specimens. However, no individual molecule or metabolite combination has reached clinical diagnostic utility. Further research using large study populations with robust patient phenotype and specimen characterisation is required if we are to make progress in identifying and validating a non-invasive diagnostic test for endometriosis.
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