Endometriosis research: animal models for the study of a complex disease.

Endometriosis is a common gynaecological disease that is characterized and defined as the presence of endometrial tissue outside the uterus, causing painful periods and subfertility in approximately 10% of women. After more than 50 years of research, little is known about the mechanisms underlying the development and establishment of this condition. Animal models allow us to study the temporal sequence of events involved in disease establishment and progression. Also, because this disease occurs spontaneously only in humans and non-human primates and there are practical problems associated with studying the disease, animal models have been developed for the evaluation of endometriosis. This review describes the animal models for endometriosis that have been used to date, highlighting their importance for the investigation of disease mechanisms that would otherwise be more difficult to elucidate, and proposing new alternatives aimed at overcoming some of these limitations.

Neuroendocrine circuitry and endometriosis: progesterone derivative dampens corticotropin-releasing hormone-induced inflammation by peritoneal cells in vitro.

Clinical symptoms of endometriosis, such as pain and infertility, can be described as persistent stressors. Such continuous exposure to stress may severely affect the equilibrium and bidirectional communication of the endocrine and immune system, hereby further aggravating the progression of endometriosis. In the present study, we aimed to tease apart mediators that are involved in the stress response as well as in the progression of endometriosis. Women undergoing diagnostic laparoscopy due to infertility were recruited (n = 69). Within this cohort, early stage of endometriosis were diagnosed in n = 30 and advanced stage of endometriosis in n = 8. Levels of progesterone in serum were determined. Frequency of progesterone receptor (PR) expression on CD56(+) and CD8(+) peritoneal lymphocytes was analysed by flow cytometry. The production of tumour necrosis factor (TNF) and interleukin (IL)-10 by peritoneal leukocytes upon stimulation with the potent stress mediator corticotropin-releasing hormone (CRH) and the progesterone derivative dydrogesterone, or both, were evaluated. Furthermore, the production of progesterone-induced blocking factor (PIBF) by peritoneal leukocytes and the expression of PR in endometriotic tissue were investigated. Levels of progesterone in serum were decreased in women with endometriosis and inversely correlated to pain scores. Furthermore, an increased frequency of CD56(+)PR(+) and CD8(+)PR(+) peritoneal lymphocytes was present in advanced endometriosis. The TNF/IL-10 ratio, reflecting cytokine secretion by peritoneal cells, was higher in cells derived from endometriosis patients and could be further heightened by CRH stimulation, whereas stimulation with dydrogesterone abrogated the CRH-mediated inflammation. Finally, the expression of PIBF by peritoneal leukocytes was increased in endometriosis. Low levels of progesterone in the follicular phase could be responsible for the progression of endometriosis and related pain. Peripheral CRH, increasing upon high psychological stress, might contribute to the peritoneal inflammation present in endometriosis. The therapeutic application of progesterone derivatives, CRH blocking agents as well as improvement of stress coping may disrupt the vicious circle between the chronic peritoneal inflammation and high perception of psychological stress in endometriosis.

Immune status, psychosocial distress and reduced quality of life in infertile patients with endometriosis.

PROBLEM: The aim of the study was to identify if (i) psychosocial factors differ in endometriosis; (ii) related psychosocial aspects alter immune markers of depression/sickness behaviour; and (iii) serum immune marker may be indicative for endometriosis. METHOD OF STUDY: We enrolled 103 women in a case-control study. Psychosocial data were obtained, serum levels of interleukin (IL)-2, IL-4, IL-5, IL-6, IL-10, IL-12, IL-13, interferon (IFN)-gamma, TNF-alpha, IFN-alpha and soluble intercellular adhesion molecule-1 (sICAM-1) were analysed. RESULTS: Among 69 eligible patients, endometriosis was diagnosed in 38 women. Patients with endometriosis reported reduced quality of life, increased stress perception/depressive symptoms; the Th1/Th2 ratio was in favour of Th1, accompanied by the increased levels of IFN-alpha. sICAM-1 levels were unaffected. No correlation could be confirmed between psychosocial and immune markers. CONCLUSION: Women with endometriosis may benefit from strategies contributing to reduction of stress and development of coping mechanisms, thus helping to break the vicious circle of inflammation, sickness behaviour and depression.

Neuroendocrine-immune disequilibrium and endometriosis: an interdisciplinary approach.

Endometriosis, a chronic disease characterized by endometrial tissue located outside the uterine cavity, affects one fourth of young women and is associated with chronic pelvic pain and infertility. However, an in-depth understanding of the pathophysiology and effective treatment strategies of endometriosis is still largely elusive. Inadequate immune and neuroendocrine responses are significantly involved in the pathophysiology of endometriosis, and key findings are summarized in the present review. We discuss here the role of different immune mechanisms particularly adhesion molecules, proteinglycan interactions, and pro-angiogenic mediators in the development and progression of the disease. Finally, we introduce the concept of endometrial dissemination as result of a neuroendocrine-immune disequilibrium in response to high levels of perceived stress caused by cardinal clinical symptoms of endometriosis.