Disappearance of the ovulation stigma in baboons (Papio anubis, Papio cynocephalus) as determined by serial laparoscopies during the luteal phase

Baboon model for the study of endometriosis

Endometriosis is a benign, estrogen-dependent disease and is now recognized as an enigmatic disease owing to its various clinical manifestations and locations. The lack of a reliable and specific method for the early detection of endometriosis often results in delayed diagnosis. So far, research has born inadequate findings regarding understanding the basic etiology or pathophysiology of endometriosis. Animal models that accurately represent the cellular and molecular changes associated with the initiation and progression of human endometriosis have significant potential to facilitate the development of better methods for the early detection and treatment of endometriosis. A number of animal model systems have been developed for the study of this disease. These models replicate many of the known salient features of human endometriosis. This review provides an insight into the use of the baboon model for studies focused on understanding human endometriosis.

Role of cytokines in endometriosis

OBJECTIVE

To review the literature on the role of cytokines in the pathogenesis of endometriosis and endometriosis-associated infertility.

DESIGN

Pertinent studies were identified by a computer search of MEDLINE. References of selected articles were hand-searched for additional citations.

RESULT(S)

Recent studies suggest that the peritoneal fluid of women with endometriosis contains an increased number of activated macrophages that secrete various local products, such as growth factors and cytokines. Levels of several cytokines were reported to be elevated in the peritoneal fluid of women with endometriosis. Because the peritoneal environment may be controlled by locally regulated factors, cytokines are believed to play a role in the development and progression of endometriosis and endometriosis-associated infertility. A possible pathogenic mechanism links cytokines with endometriosis.

CONCLUSION(S)

Cytokines, which are produced by many cell types including endometriotic tissues, play diverse roles in the pathogenesis of endometriosis and endometriosis-associated infertility. More studies about the specific role of these cells and soluble factors are needed to improve understanding of endometriosis and to develop novel therapies.

Pelvic inflammation induced by diagnostic laparoscopy in baboons

OBJECTIVE

To test the hypothesis that diagnostic laparoscopy can cause pelviperitoneal inflammation.

DESIGN

Retrospective analysis of data collected during a prospective controlled study in baboons.

SETTING

An academic research environment.

ANIMAL(S)

Samples were collected during laparoscopies in female baboons at the Institute of Primate Research, Kenya.

INTERVENTION(S)

In the first part of the study, 44 laparoscopies were performed in 16 baboons (5 with a normal pelvis, 11 with endometriosis) during the luteal phase, with a time interval of 1 month. In the second part of the study, 53 laparoscopies were performed in 15 baboons (6 with a normal pelvis, 9 with endometriosis) during the late follicular and luteal phases of one cycle, with a median time of 3-4 days between each laparoscopy.

MAIN OUTCOME MEASURE(S)

Peritoneal fluid (PF) was measured and analyzed for white blood cell (WBC) concentrations and, in the second part of the study, for the distribution of lymphocyte subsets (CD3, CD4, CD8, and CD20) and for the presence of cytokines transforming growth factor-beta1, interleukin (IL)-6, and IL-10.

RESULT(S)

In the first part of the study, PF volumes and WBC concentrations were comparable at the baseline and follow-up laparoscopies. In the second part of the study, PF obtained at the second laparoscopy showed a 10-fold increase in volume, a 3-fold increase in WBC concentration, a 10-fold increase in IL-6 concentration, and a 2-fold increase in transforming growth factor-beta1 concentration when compared with PF obtained at the first laparoscopy. The PF subset of granulocytes and CD3-positive cells was higher and the PF subset of macrophages was lower at follow-up laparoscopies than at the baseline laparoscopy.

CONCLUSION(S)

Diagnostic laparoscopy can cause peritoneal inflammation in baboons.

Clinical relevance of the baboon as a model for the study of endometriosis

OBJECTIVE

To review the value of the baboon as a model for the study of endometriosis.

DATA IDENTIFICATION AND SELECTION

Studies performed at the Institute of Primate Research in Nairobi, Kenya (1990-1994), and published in peer-reviewed journals.

RESULT(S)

Spontaneous endometriosis was found in about 25% of the baboons, and its prevalence increased with the duration of captivity. The laparoscopic appearance, pelvic localization, and microscopic aspects of the disease were similar to endometriosis in women. Microscopic endometriosis in macroscopically normal peritoneum was rare. Sampson's hypothesis (i.e., retrograde menstruation causes endometriosis) was supported by the increased incidence of retrograde menstruation in baboons with spontaneous endometriosis, the observation that cervical occlusion could cause retrograde menstruation and endometriosis, and the finding that intrapelvic injection of menstrual endometrium caused experimental moderate to severe endometriosis similar to the spontaneous disease. During follow-up of more than 2 years, endometriosis in baboons appeared to be a progressive disease, with active remodeling between several types of lesions. Progression was stimulated by high-dose immunosuppression. Fertility was normal in baboons with minimal disease but was reduced in baboons with mild, moderate, or severe endometriosis, possibly related to an increased incidence and recurrence of the luteinized unruptured follicle syndrome.

CONCLUSION(S)

The baboon is a good model for the study of endometriosis.