Altered expression of interleukin-18 in the ectopic and eutopic endometrium of women with endometriosis

doi:10.1016/j.jri.2006.03.003

Journal of Reproductive Immunology

Volume 72, Issues 1–2, December 2006, Pages 108-117

https://doi.org/10.1016/j.jri.2006.03.003 Get rights and content

Abstract

Objective

: This study has investigated the expression of interleukin (IL)-18 in the eutopic and ectopic endometrium of women with endometriosis and the role of IL-18 on the pathogenesis of endometriosis.

Methods

: Endometriotic tissue specimens and endometrium specimens were obtained from patients with endometriosis. IL-18 protein was determined by immunohistochemical analysis. Expression levels of IL-18 mRNA were analyzed by reverse transcriptase (RT)-PCR.

Results

: IL-18 was detected in the glandular epithelial and stromal cells of eutopic and ectopic endometrium. RT-PCR analysis showed that endometrial IL-18 mRNA expression levels were significantly higher at the secretory phase than the proliferative phase in normal women, but not in patients with endometriosis. IL-18 mRNA expression levels were lower in the ectopic endometrium than in the eutopic endometrium of women with endometriosis. IL-18 mRNA levels in both ectopic and eutopic endometrium of patients with endometriosis were lower than in endometrium of women without endometriosis.

Conclusion

: Ectopic and eutopic endometrial IL-18 was down-regulated in women with endometriosis, suggesting that IL-18 might play a pathogenic role in the formation of endometriosis.

Introduction

Endometriosis is a common benign gynecologic disease that affects about 10% of women of reproductive age (Oku et al., 2004). The exact pathogenesis of this enigmatic disease is still unclear. To date, the theory of retrograde menstruation that postulates reflux of shed endometrial tissue through the fallopian tube with implantation on the peritoneal surface is widely accepted. Although dissemination of endometrial cells into ectopic locations during menses appears to be a common phenomenon, ectopic implantation of these cells only occurs infrequently. It seems that menstrual debris in women with endometriosis may be more prone to implant and invade the peritoneum or ovary than in normal women. An inappropriate immunologic response in the local peritoneal environment may play a crucial role in survival and development of the implanted ectopic endometrium. Increased release of inflammatory cytokines is an important component of the immunologic response. It has been shown that the expression levels of some cytokines in the eutopic endometrium of women with endometriosis differ from that of normal women (Arici, 2002, Jolicoeur et al., 1998, Khan et al., 2003).

Interleukin (IL)-18 plays an important role in immunomodulatory and anti-tumor process. IL-18 is produced as a 24 kDa precursor that requires cleavage by IL-1-converting enzyme (also called caspase-1) in order to generate its biologically active 18 kDa monomer (Ghayur et al., 1997, Gu et al., 1997). IL-18, together with IL-12, induces interferon (IFN)-γ and initiates production of pro-inflammatory cytokines. IL-18 also promotes T-helper 1 (Th1) responses and cytotoxic activity of natural killer (NK) cells (Takeda et al., 1998). Moreover, IL-18 stimulates macrophages to induce cyclooxygenase (COX)-II and, subsequently, prostaglandins (PGs), which mediate various biological responses such as pain (Kashiwamura et al., 2002). A previous study indicated that IL-18 was constitutively expressed in endometrial epithelial cells and stromal cells throughout the menstrual cycle (Yoshino et al., 2001).

A study from our hospital has suggested that IL-18 concentrations in peritoneal fluid (PF) were significantly lower in patients with endometriosis than in women without endometriosis (Zhang et al., 2004). We hypothesized that IL-18 might be involved in the pathogenesis of endometriosis and that expression levels of IL-18 might be different in the eutopic endometrium of patients with endometriosis and normal women. In the present study, we have tried to determine the expression of IL-18 in the eutopic and ectopic endometrium of patients with endometriosis. We determined also the expression of IL-18 in endometrium at the different phases of the menstrual cycle of women with or without endometriosis.

Section snippets

Patient population

Fifty-seven women voluntarily participated in this study. Written consent from all women and approval by the Institutional Review Committee of the Medical School, Zhejiang University, was obtained for this study. None of the participants had pelvic inflammatory disease or cancer, and none had received any hormonal therapies 3 months prior to the present study.

The diagnosis of endometriosis was confirmed by visual impression at the time of surgery and histological examination of resected

Immunohistochemical analysis

Immunohistochemical staining with anti-IL-18 antibody was detected in both the glandular epithelial and stromal cells of eutopic endometrium and endometriotic lesions. Fig. 1 shows that IL-18 expression was localized in the cytoplasm of glandular epithelial and stromal cells. There was no signal detected in the negative controls.

Semi-quantitative RT-PCR analysis

RT-PCR analysis indicated that IL-18 mRNA was expressed in all samples. As shown in Table 2, the relative level of IL-18 mRNA expression in ectopic endometrium (0.73 ±

Discussion

The expression of IL-18 in the ectopic and eutopic endometrium of women with endometriosis has been investigated. We found that IL-18 mRNA levels were significantly lower in the ectopic and eutopic endometrium in women with endometriosis than in normal women. We demonstrated also that expression levels of IL-18 mRNA were significantly higher at the secretory phase than the proliferative phase in normal women, but not in women with endometriosis.

It is well-known that IL-18 plays an important

Acknowledgement

This work was supported in part by National Science Foundation of China (No. 30471642).

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Citation Excerpt :
IL-18, which is consistently among the 4 most strongly weighted factors (Figs 1B, 2B, and 3B), is produced by many cell types, including stromal and epithelial cells in the endometrium, where it regulates activation and cytokine production of uNK cells and is implicated in vascular remodeling in pregnancy (69–72). Consistent with our findings of a negative association with endometriosis, transcriptional analyses of endometrial biopsy specimens showed that IL-18 mRNA expression was higher in normal women than in women with endometriosis (72). Also consistent with our findings of great variability among a patient population with infertility (Supplemental Table 2) are reports that in patients with recurrent implantation failure, IL-18 is lower in the preimplantation endometrium in some patients and higher in others, underscoring the need for patient stratification in immune-targeted therapies in this population (73, 74).
To evaluate whether endometrial molecular profiles distinguish subsets of patients according to clinical characteristics, and to infer dysregulated immune networks, by measuring cytokines, chemokines, and growth factors in endometrial biopsy specimens from a cohort of infertile women with a high incidence of endometriosis.
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Department of Gynecology at a university hospital.
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Endometrial biopsies were performed during surgery. Fertility outcome and clinical parameters were registered preoperatively and after 6 months.
The concentrations of 48 factors in endometrial biopsy specimens were analyzed with respect to clinical status in univariate and multivariate frameworks.
The concentrations of 44 factors from endometrial tissues of 74 patients were suitable for analysis. Although the tissue concentrations of interleukin (IL)15, IL-7, and interferon γ-induced protein (IP)-10 were individually lower in patients with endometriosis than in those without endometriosis, the differences were not significant after multiple comparison. However, multivariate modeling incorporating covariation showed separation between subsets of endometriotic and nonendometriotic patients, based predominantly on IP-10, monocyte chemoattractant protein-1, IL-16, and IL-18; this result was independent of cycle and fertility status. Analysis restricted to endometrial tissues from the secretory phase separated endometriotic and nonendometriotic patients by a combination of IL-15, IP-10, monocyte chemoattractant protein-1, IL-16, and IL-18. This combination suggests a uterine natural killer cell defect. We found no significant correlations between endometrial cytokines and fertility outcome.
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Las concentraciones de 48 factores en especímenes de biopsia endometrial se analizaron con respecto al estatus clínico en marcos univariable y multivariable.
Las concentraciones de 44 actores de tejido endometrial de 74 pacientes fueron adecuadas para el análisis. Aunque las concentraciones de interleucina (IL) 15, IL-7 e IL-10 fueron individualmente menores en las pacientes con endometriosis que en aquellas sin endometriosis, las diferencias no fueron significativas tras la comparación múltiple. Sin embargo, un modelo multivariable incorporando covarianza mostró separación entre subgrupos de pacientes con y sin endometriosis, basados principalmente en IP-10, MCP-1, IL-16 e IL-18. Este resultado fue independiente del ciclo y el estado de fertilidad. Un análisis restringido a tejidos endometriales de fase secretoria separó a pacientes con y sin endometriosis mediante una combinación de IL-15, IP-10, MCP-1, IL-16 e IL-18. Esta combinación sugiere un defecto de células NK. No hallamos correlaciones significativas entre citoquinas endometriales y resultados de fertilidad.
Una firma molecular en tejido endometrial fue capaz de distinguir pacientes con y sin endometriosis, implicando a las células NK en la endometriosis.
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Endometriosis is an estrogen-dependent chronic gynecological disease characterized by the development of endometrial tissue outside the uterus, especially in the ovaries, pelvic peritoneum, and rectovaginal septum. It affects approximately 150 million women worldwide and 7%–12% of women of reproductive age. The incidence of the disease in infertile patients can increase up to 50%, and 80% of unexplained infertility may be associated with endometriosis. Endometriosis is seen in 25% of patients who undergo assisted reproductive treatments (ART), and ovarian endometriosis is found in 20%–40% of these patients. Despite the scientifically supported relationship between endometriosis and infertility, it is difficult to prove a correlation between endometriosis and infertility since endometriosis has an impact on fertility status via different mechanisms given the heterogeneity of the disease. The mechanisms that lead to infertility in patients with endometriosis are the distortions of the pelvic anatomy because of the chronic inflammation and fibrosis, impaired endometrial receptivity, decreased ovarian reserve and oocyte quality and dysregulation of the immune system. In the management of the endometriosis-associated infertility, intrauterine insemination, ART, and surgery are the treatment options of which surgery has controversies. Treatment should be opted individually according to the woman’s age, ovarian reserve, presence of the cyst unilaterally or bilaterally, symptoms, presence of radiological features suggestive of malignancy, and previous history of surgery. And also, women with endometriosis should definitely seek fertility preservation counseling.
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This supports the concept that secretory phase endometrium immune phenotype during severe ovarian endometriosis may be one of the causes of primary infertility functioning in a multi-modal manner (Lalitkumar et al., 2005; Sengupta and Ghosh 2014; Lessey and Kim, 2017; Sanchez et al., 2017; Sengupta et al., 2017; Focarelli et al., 2018; Robertson et al., 2018; Bulun et al., 2019). Our observation that higher IL18 concentrations are detected in the culture medium conditioned by control ESC compared with that conditioned by OE-ESC corroborates well with the earlier reports (Huang et al., 2006; Luo et al., 2006). IL18 belongs to the IL1 family of cytokines and is constitutively expressed in large number of cells and its dysregulation can cause inflammatory diseases (Baker et al., 2019).
Do endometrial stromal cells from primary infertile patients with severe ovarian endometriosis display differential secretory profiles of inflammation-associated cytokines during the implantation window that may cause infertility?
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CCL3, CCL4, CCL5, CXCL10, FGF2, IFNG, IL1RN, IL5, TNFA, and VEGF could be detected only in the conditioned media of stromal cells obtained from the ovarian endometriosis group. Among other cytokines detected in the conditioned media of both groups, CCL2 (P = 0.0018), CSF3 (P = 0.0017), IL1B (P = 0.0066), IL4 (P = 0.036), IL6 (P = 0.0039) and IL13 (P = 0.036) were found to be higher, whereas the concentration of IL18 was lower (P = 0.023) in the ovarian endometriosis group. Concentrations of CCL2, IL1B, IL4 and IL13 in conditioned medium reflected significant diagnostic performance for predicting ovarian endometriosis. Cellular phenotypic validation in vitro revealed an enhanced proliferative phenotype (P = 0.046) with no change in cell migratory capacity of endometrial stromal cells from the ovarian endometriosis group.
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Soluble CD200 in secretory phase endometriosis endometrial venules may explain endometriosis pathophysiology and provide a novel treatment target
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Endometriosis is defined as the presence of endometrial tissue outside the uterine cavity and is considered a benign gynecologic condition; however, in some cases, it may be aggressive. The pathogenesis of endometriosis is complex and multifactorial. Despite being one of the most widely studied gynecologic diseases, its pathogenesis remains uncertain. The intrinsic endometrial abnormalities thought to be associated with endometriosis include abnormal expression of genes, modification of endometrial response to hormones such as progesterone; increased nerve density, and oxidative stress. Evaluation of the endometrium in patients with endometriosis is an important line of investigation in the pathophysiology of the disease. It has been suggested that investigation of eutopic endometrium may help to achieve this goal. Presented herein is a literature review and a comprehensive evaluation of the role of eutopic endometrium in pelvic endometriosis. Clinical correlations of the disease are highlighted, with the objective of understanding the role of eutopic endometrium in endometriosis.
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¹: The authors have equal contribution to the present study.

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Altered expression of interleukin-18 in the ectopic and eutopic endometrium of women with endometriosis

Abstract

Objective

Methods

Results

Conclusion

Introduction

Section snippets

Patient population

Immunohistochemical analysis

Semi-quantitative RT-PCR analysis

Discussion

Acknowledgement

J. Reprod. Immunol.

Fertil. Steril.

Fertil. Steril.

Fertil. Steril.

Fertil. Steril.

Fertil. Steril.

Lab. Invest.

Immunity

Fertil. Steril.

Fertil. Steril.

Local cytokines in endometrial tissue: the role of interleukin-8 in the pathogenesis of endometriosis

Ann. N. Y. Acad. Sci.

Interleukin-18 acts as an angiogenesis and tumor suppressor

FASEB J.

Immuno-endocrine interactions in early pregnancy

Hum. Reprod.

Cytokines in implantation

Hum. Reprod. Update