Endometrioma: From Pathogenesis to Clinical Management

Dysregulation of the ADAM17/Notch signalling pathways in endometriosis: from oxidative stress to fibrosis

STUDY QUESTION

Is oxidative stress associated with the A disintegrin and metalloproteases (ADAM) metallopeptidase domain 17 (ADAM17)/Notch signalling pathway and fibrosis in the development of endometriosis?

SUMMARY ANSWER

Oxidative stress is correlated with hyperactivation of the ADAM17/Notch signalling pathway and a consequent increase in fibrosis in patients with endometriosis.

WHAT IS KNOWN ALREADY

It is nowadays accepted that oxidative stress plays an important role in the onset and progression of endometriosis. Oxidative stress is able to induce the synthesis of some members of the 'ADAM' family, such as ADAM17. ADAM17/Notch signalling is dysregulated in other profibrotic and inflammatory diseases.

STUDY DESIGN, SIZE, DURATION

This was a prospective laboratory study conducted in a tertiary-care university hospital between January 2011 and April 2013. We investigated non-pregnant, younger than 42-year-old patients (n = 202) during surgery for a benign gynaecological condition.

PARTICIPANTS/MATERIALS, SETTING, METHODS

After complete surgical exploration of the abdominopelvic cavity, 121 women with histologically proven endometriosis and 81 endometriosis-free control women were enrolled. Peritoneal fluid (PF) samples were obtained from all the study participants during surgery in order to detect advanced oxidation protein products (AOPPs) and metalloproteinase activity of ADAM17. Stromal cells from endometrial specimens (n = 8) were obtained from endometrium of control patients (Cs), and from eutopic (Es) and ectopic (Ps) endometrium of patients with deep infiltrating endometriosis (DIE) (n = 8). ADAM17, Notch and the fibrosis markers α-smooth muscle actin (α-SMA) and type-I collagen were assessed using immunoblotting in all the endometrial samples obtained. Additionally, fibrosis was assessed after using Notch cleavage inhibitors (DAPT and FLI-06). Notch and fibrosis were also evaluated after stimulation of stromal endometrial cells with ADAM17 purified protein, increasing concentrations of H2O2 and primary cell culture supernatants.

MAIN RESULTS AND THE ROLE OF CHANCE

Patients with DIE presented higher PF AOPP and ADAM17 protein levels than controls (P < 0.01 and P < 0.05, respectively). In addition, these two markers were positively correlated (r = 0.614; P < 0.001). At the cellular level, ADAM17 activity was increased in Es and Ps compared to Cs (P < 0.001 and P < 0.01, respectively). Furthermore, Ps presented hyperactivation of Notch signalling (P < 0.05) and augmentation of fibrosis markers (P = 0.009 for α-SMA and P = 0.015 for type-I collagen) compared to controls. The use of DAPT and FLI-06 reduced both fibrosis markers in Ps but not in Cs. Stimulation with ADAM17, H2O2 and Ps supernatant culture significantly increased Notch and fibrosis in both Ps and Cs.

LARGE SCALE DATA

N/A.

LIMITATIONS REASONS FOR CAUTION

The control group consisted of women who underwent surgery for benign gynaecological conditions, which could lead to biases because some of these conditions may cause alterations in oxidative stress and the ADAM17/Notch pathways. The small sample size of endometrial biopsies used for each group of patients (n = 8) is a limitation of the study, and results should be interpreted with caution.

WIDER IMPLICATIONS OF THE FINDINGS

We propose a novel pathway in endometriosis pathogenesis that correlates oxidative stress, hyperactivation of ADAM17/Notch signalling and a consequent increase in fibrosis. This study suggests that Notch signalling plays a key role in the fibrotic processes that take place in ectopic lesions of patients with DIE, as already observed in other pro-fibrotic diseases.

STUDY FUNDING AND COMPETING INTEREST(S)

This work was supported by grants from University Paris Descartes, INSERM and Fundación Alfonso Martín Escudero. The authors have no competing interests to declare.

Pathogenetic Mechanisms of Deep Infiltrating Endometriosis

Endometriosis is a benign gynecologic disease, affecting women of reproductive age associated with chronic pelvic pain, dysmenorrhea, dyspareunia and infertility. Ovarian endometrioma (OMA), superficial peritoneal endometriosis (SPE), and deep infiltrating endometriosis (DIE) are, till now, recognized as major phenotypes. The discussion is to know whether they share the same pathogenetic mechanisms. Till today, DIE is recognized as the most severe clinical form of endometriosis and has a complex clinical management. The DIE lesions have been considered in the present article, without distinguishing between the anterior (bladder) or the posterior (vagina, uterosacral ligaments, rectum, and ureter) compartment. The present knowledge indicates that hormonal function (estrogen and progesterone receptors) and immunological factors, such as peritoneal macrophages, natural killer cells, and lymphocytes, are critically altered in DIE. The aggressive behavior of DIE may be explained by the highly decreased apoptosis (nuclear factor kappa-light-chain-enhancer of activated B cells [NF-kB], B-cell lymphoma 2 [Blc-2], and anti-Mullerian hormone) and by the increased proliferation activity related to oxidative stress (NF-kB, reactive oxygen species, extracellular regulated kinase (ERK), advanced oxidation protein product). Invasive mechanisms are more expressed (matrix metalloproteinases and activins) in DIE in comparison to the OMA and SPE. Correlated with the increased invasiveness are the data on very high expression of neuroangiogenesis (nerve growth factor, vascular endothelial growth factor, and intercellular adhesion molecule) genes in DIE. Therefore, at the present time, several of the DIE pathogenetic features result specific in comparison to other endometriosis phenotypes, pleading for the existence of a specific entity. These evidence of specific pathogenetic features of DIE may explain the more severe symptomatology related to this form of endometriosis and suggest possible future target medical treatments.

[Endometriosis: increasing concentrations of serum interleukin-1β and interleukin-1sRII is associated with the deep form of this pathology]

OBJECTIVES

To assess interleukin-1β (IL-1β) and its inhibitory soluble interleukin-1 receptor type II (IL-1sRII) levels into the serum of patients with various forms of endometriosis and normal women, and investigate the correlation with disease activity.

PATIENTS AND METHODS

In this prospective laboratory study (2005-2010), 510 women with histologically proven endometriosis and 93 endometriosis-free controls have been enrolled. Laparoscopic complete exploration of the abdominopelvic cavity and blood samples have been performed in each patient. For each serum, IL-1β and IL-1sRII have been evaluated using Elisa.

RESULTS

IL-1β and IL-1sRII have been respectively detectable in 64% and 54.6% of serum samples from all 603 women studied. IL-1β was higher in women with deep infiltrating endometriosis (DIE) (mean 10.0pg/mL [0.005-416.2]) than in endometriosis-free women (mean 0.5pg/mL [0.01-1.7], P<0.01) or in women with superficial endometriosis (SUP) (mean 0.6pg/mL [0.1-2.9], P<0.01). Also, IL-1sRII was higher in DIE (mean 236.7pg/mL [0.9-6975]) than in the witness group (mean 85.0pg/mL [1-235.2], P<0.05) or in SUP (mean 85.1pg/mL [0.6-302], P<0.01).

CONCLUSION

This study highlights both a marked significant increase in serum IL-1β and IL-1sRII levels in DIE compared to SUP and normal women and suggests that a defect in the control of IL-1 can impact the pathophysiology of endometriosis.