Clustering of PCOS-like traits in naturally hyperandrogenic female rhesus monkeys

Study question

Do naturally occurring, hyperandrogenic (≥1 SD of population mean testosterone, T) female rhesus monkeys exhibit traits typical of women with polycystic ovary syndrome (PCOS)?

Summary answer

Hyperandrogenic female monkeys exhibited significantly increased serum levels of androstenedione (A4), 17-hydroxyprogesterone (17-OHP), estradiol (E2), LH, antimullerian hormone (AMH), cortisol, 11-deoxycortisol and corticosterone, as well as increased uterine endometrial thickness and evidence of reduced fertility, all traits associated with PCOS.

What is known already

Progress in treating women with PCOS is limited by incomplete knowledge of its pathogenesis and the absence of naturally occurring PCOS in animal models. A female macaque monkey, however, with naturally occurring hyperandrogenism, anovulation and polyfollicular ovaries, accompanied by insulin resistance, increased adiposity and endometrial hyperplasia, suggests naturally occurring origins for PCOS in nonhuman primates.

Study design, size, duration

As part of a larger study, circulating serum concentrations of selected pituitary, ovarian and adrenal hormones, together with fasted insulin and glucose levels, were determined in a single, morning blood sample obtained from 120 apparently healthy, ovary-intact, adult female rhesus monkeys (Macaca mulatta) while not pregnant or nursing. The monkeys were then sedated for somatometric and ultrasonographic measurements.

Participants/materials, setting, methods

Female monkeys were of prime reproductive age (7.2 ± 0.1 years, mean ± SEM) and represented a typical spectrum of adult body weight (7.4 ± 0.2 kg; maximum 12.5, minimum 4.6 kg). Females were defined as having normal (n = 99) or high T levels (n = 21; ≥1 SD above the overall mean, 0.31 ng/ml). Electronic health records provided menstrual and fecundity histories. Steroid hormones were determined by tandem LC-MS-MS; AMH was measured by enzymeimmunoassay; LH, FSH and insulin were determined by radioimmunoassay; and glucose was read by glucose meter. Most analyses were limited to 80 females (60 normal T, 20 high T) in the follicular phase of a menstrual cycle or anovulatory period (serum progesterone <1 ng/ml).

Main results and the role of chance

Of 80 monkeys, 15% (n = 12) exhibited classifiable PCOS-like phenotypes. High T females demonstrated elevations in serum levels of LH (P < 0.036), AMH (P < 0.021), A4 (P < 0.0001), 17-OHP (P < 0.008), E2 (P < 0.023), glucocorticoids (P < 0.02-0.0001), the serum T/E2 ratio (P < 0.03) and uterine endometrial thickness (P < 0.014) compared to normal T females. Within the high T group alone, anogenital distance, a biomarker for fetal T exposure, positively correlated (P < 0.015) with serum A4 levels, while clitoral volume, a biomarker for prior T exposure, positively correlated (P < 0.002) with postnatal age. Only high T females demonstrated positive correlations between serum LH, and both T and A4. Five of six (83%) high T females with serum T ≥2 SD above T mean (0.41 ng/ml) did not produce live offspring.

Large scale data

N/A.

Limitations, reasons for caution

This is an initial study of a single laboratory population in a single nonhuman primate species. While two biomarkers suggest lifelong hyperandrogenism, phenotypic expression during gestation, prepuberty, adolescence, mid-to-late reproductive years and postmenopause has yet to be determined.

Wider implications of the findings

Characterizing adult female monkeys with naturally occurring hyperandrogenism has identified individuals with high LH and AMH combined with infertility, suggesting developmental linkage among traits with endemic origins beyond humans. PCOS may thus be an ancient phenotype, as previously proposed, with a definable pathogenic mechanism(s).

Study funding/competing interest(s)

Funded by competitive supplement to P51 OD011106 (PI: Mallick), by P50 HD028934 (PI: Marshall) and by P50 HD044405 (PI: Dunaif). The authors have no potential conflicts of interest.

An overview of molecular and cellular mechanisms associated with porcine pregnancy success or failure

Prenatal mortality remains one of the major constraints for the commercial pig industry in North America. Twenty to thirty per cent of the conceptuses are lost early in gestation and an additional 10-15% is lost by mid-to-late gestation. Research over the last two decades has provided critical insights into how uterine capacity, placental efficiency, genetics, environment, nutrition and immune mechanisms impact successful conceptus growth; however, the exact cause and effect relationship in the context of foetal loss has yet to be determined. Similar to other mammalian species such as the human, mouse, rat, and primates, immune cell enrichment occurs at the porcine maternal-foetal interface during the window of conceptus attachment. However, unlike other species, immune cells are solely recruited by conceptus-derived signals. As pigs have epitheliochorial placentae where maternal and foetal tissue layers are separate, it provides an ideal model to study immune cell interactions with foetal trophoblasts. Our research is focused on the immune-angiogenesis axis during porcine pregnancy. It is well established that immune cells are recruited to the maternal-foetal interface, but their pregnancy specific functions and how the local milieu affects angiogenesis and inflammation at the site of foetal arrest remain unknown. Through a better understanding of how immune cells modulate crosstalk between the conceptus and the mother, it might be possible to therapeutically target immune cells and/or their products to reduce foetal loss. In this review, we provide evidence from the literature and from our own work into the immunological factors associated with porcine foetal loss.

Cellular and molecular events in early and mid gestation porcine implantation sites: a review

Commercial, North American pork breeds (Sus scrofa) experience significant loss of genetically-normal conceptuses during the peri-implantation (attachment) period and at mid-gestation (day 50 to 90 of the 114 day porcine gestation interval). Although exact causes for these losses are not defined, asynchronous in-utero development and deficits in vascularization of the endometrium and placenta appear to be involved. Understanding of normal maternal-fetal dialogue is critical to develop breeding or therapeutic strategies that improve fetal health and overall litter size in commercial pigs. The non-invasive, epitheliochorial porcine placenta permits investigation of maternal or fetal compartments without cross contaminating cells. We developed and use protocols to capture single, homogenous populations of porcine cells (endometrial lymphocytes, dendritic or endothelial cells) from histological sections using laser capture microdissection (LCM), a powerful tool for study of gene expression that reflects the in vivo environment. These data are compared with gene expression in biopsies of endometrium and of trophoblast from the same, attachment sites. Here we review justifications for selection of the genes we have studied and our published and in progress work. These data provide new insights into the roles of the endometrial immune environment in the regulation of the success and failure of porcine conceptuses.