Katrine Bay

Testicular descent: INSL3, testosterone, genes and the intrauterine milieu

Complete testicular descent is a sign of, and a prerequisite for, normal testicular function in adult life. The process of testis descent is dependent on gubernacular growth and reorganization, which is regulated by the Leydig cell hormones insulin-like peptide 3 (INSL3) and testosterone. Investigation of the role of INSL3 and its receptor, relaxin-family peptide receptor 2 (RXFP2), has contributed substantially to our understanding of the hormonal control of testicular descent. Cryptorchidism is a common congenital malformation, which is seen in 2–9% of newborn boys, and confers an increased risk of infertility and testicular cancer in adulthood. Although some cases of isolated cryptorchidism in humans can be ascribed to known genetic defects, such as mutations in INSL3 or RXFP2, the cause of cryptorchidism remains unknown in most patients. Several animal and human studies are currently underway to test the hypothesis that in utero factors, including environmental and maternal lifestyle factors, may be involved in the etiology of cryptorchidism. Overall, the etiology of isolated cryptorchidism seems to be complex and multifactorial, involving both genetic and nongenetic components.

Insulin-Like Factor 3 Levels in Second-Trimester Amniotic Fluid

BACKGROUND According to animal studies, the testicular Leydig cell hormone insulin-like factor 3 (Insl3) exerts a fundamental role in abdominal testis translocation, which occurs in the beginning of the second trimester in humans. Despite this, human prenatal INSL3 production has been poorly investigated. METHODS Amniotic fluid from 91 pregnant women undergoing amniocentesis was analyzed for INSL3 and testosterone (T) levels. Data were related to gestational age (15-25 wk) at amniocentesis and to sex (45 males and 48 females). RESULTS INSL3 was present in amniotic fluid from all but one of the investigated male fetuses (range: <0.02-0.36 ng/ml; mean +/- sd: 0.12 +/- 0.07), whereas the hormone was undetectable in the female fetuses. T was significantly higher in male (range: 0.54-1.71 nmol/liter; mean +/- sd: 1.04 +/- 0.30) as compared with in female amniotic fluid (range: 0.19-0.50 nmol/liter; mean +/- sd: 0.34 +/- 0.06) (P < 0.001). In males there was no correlation between INSL3 and T. A statistically borderline negative association was found between INSL3 and gestational age (P = 0.07), whereas the corresponding association was not significant for T (P = 0.12). In contrast, T in females correlated positively with gestational age (P = 0.02). CONCLUSIONS INSL3 is clearly present in human male amniotic fluid in the second trimester, where abdominal testis translocation takes place. In contrast, the hormone is undetectable in female amniotic fluid. The prenatal presence of INSL3 supports the hypothesis that this hormone is essential for testicular descent in humans.

Klinefelter syndrome: the forgotten syndrome: basic and clinical questions posed to an international group of scientists.

Sex chromosomes are important for proper sexual differentiation. Females carry two X chromosomes (46,XX), whereas males carry one X chromosome and one Y chromosome (46,XY). The SRY (sex-determining region of Y chromosome) gene is located on the Y chromosome, and directs the development of the foetal gonads into testes, although many other genes are also important for proper sexual development of the male foetus. When two (or more) X chromosomes are present in a cell (as in healthy females or in sex chromosome disorders like 47,XXY), only one is active. The additional X chromosome is mostly inactivated, and the condensed X chromatin can be seen as a Barr body in the periphery of the cell nucleus. The genes located in the two small pseudoautosomal regions (PAR) remain active in both men and women; therefore, men with KS are functionally trisomic for these genes. In addition, some genes in the region of the X chromosome, which are not homologous to the Y chromosome and thus are normally inactivated, do escape inactivation, and these genes are functionally duplicated in KS males (analogous to the situation in females). Following the first publication by Klinefelter et al. (1) on the clinical phenotype of KS in 1942, and the discovery by Jacobs and Strong in 1959 that the aetiology was an abnormal chromosome constitution with an extra X chromosome (2), several early research papers reported a heterogeneous symptomatology of men with the 47,XXY karyotype. However, during recent decades there has been relatively little further basic or clinical research in this area. In comparison, many more papers have been published regarding girls with the much rarer condition Turner syndrome, particularly because the use of growth hormone was introduced for the management of the disorder. Therefore, our basic knowledge of the genetic, endocrine, psychological and social aspects of KS, remains very limited. Even relatively simple and practical questions concerning its management have not been fully addressed. Since our department was established in 1990, we have cared for more than 200 patients with KS, and have carried out a number of research projects (3). However, we still have more questions than answers; in fact, the number of questions concerning KS is sharply increasing. Therefore we felt that the time was ripe to gather a group of leading researchers in paediatrics, endocrinology, genetics and psychology for a workshop on KS. Thus, a workshop was held on 6–8 May 2010 at Rigshospitalet, Copenhagen University Hospital. The participants considered several questions, only some of which could be answered. However, as seen on the following pages in this special issue of Acta Paediatrica containing the proceedings, many research ideas were presented during the meeting.

Endocrine disrupters: we need research, biomonitoring and action

The majority of chemicals so far identified as having endocrine-disrupting (ED) abilities are organic compounds. Paradoxically, up to about 200 years ago organic compounds were only produced by living organisms. Examples are our own hormones and plant phytoestrogens, which together with many other naturally occurring organic compounds have been in our milieu for millions of years. However, with the evolvement of synthetic organic chemistry during the latter half of the 19th century, ignited by the petrochemical industry and the recognition of oil and gas as a vast and cheap source of organic raw material, the synthesis and development of new organic compounds literarily exploded. At the turn of the millennium, an estimated 30,000 new organic chemicals were on the market, with some 1000 new compounds being added annually (Barney, 1980). Thus, people today are likely to be exposed to thousands of organic chemicals that did not exist less than four generations ago. We need to acknowledge that the development of the petrochemical industry was a crucial prerequisite for the industrial revolution, and thus for the subsequent prosperity and development of the Western world. It has enabled the development of new medicines that have improved and saved lives. Today’s modern living is filled with products and utensils consisting of such new materials, which make our everyday lives easier and safer. However, these obvious benefits must not make us blind to the fact that among all these new chemicals, some have turned out to be harmful to endocrine systems. Few of them, including pesticides, were designed to exert endocrine activities. But for many EDCs, their endocrine activity was not intended or foreseen and was only detected later as a result of animal testing or after exposure to wildlife and humans had occurred. It is important to keep in mind that the research field on endocrine disruption from the start was spurred by observations of increasing trends in the incidence of hormone related diseases and conditions in wildlife and human populations (Toppari et al., 1996; Gee, 2012). Some trends seen in wildlife have improved significantly following better cleansing of wastewater. Although trends in some reproductive problems seen in human populations have slowed down in some countries, they do not seem to have reversed (for review, see Skakkebaek et al., 2016). The fact remains that endocrine disruption is occurring in human populations; perhaps best documented by the increase in incidence rates of cancer in some endocrine organs, including breast, testicular, pancreas and thyroid cancer. [(Kilfoy et al., 2009; Znaor et al., 2015), see also Fig. 1, which contains data from the National Danish Cancer Registry; the first national cancer registry in the world (Wagner, 1991)]. It is also well documented that poor semen quality is very common among young men in industrialised countries (Jorgensen et al., 2012; Hart et al., 2015). Environmental factors are undoubtedly involved and endocrine-disrupting chemicals (EDCs) are among the suspects (WHO & UNEP Report 2013).

Reproductive Hormone Profiles during Imatinib Therapy in Men with Chronic Myeloid Leukemia

Imatinib side effects related to testicular function have been reported in male patients with chronic myeloid leukemia. These include decreased testosterone levels, gynecomastia and impaired spermatogenesis. To further investigate testicular function in relation to imatinib treatment, a longitudinal study on reproductive hormone profiles was conducted in 17 male patients with chronic myeloid leukemia. Blood samples were taken before and at one or more time points during imatinib therapy. Serum samples were analyzed for the hormones testosterone, estradiol, and luteinizing hormone (LH) to reflect testicular Leydig cell function. Sex hormone-binding globulin (SHBG) serum levels were measured to evaluate free testosterone, and serum levels of inhibin B and follicle stimulating hormone were measured to reflect spermatogenesis. Out of the 17 patients included in the study, one patient developed gynecomastia after 7-10 months of therapy. Testosterone levels were generally low in the patients both before and during the study, and did not change in response to imatinib therapy. Conversely, SHBG levels decreased transiently at 3 and 6-9 months of therapy (p=0.002 and p=0.008, respectively). Estradiol levels decreased at 12-15 months of therapy (p=0.048). LH and hormones reflecting spermatogenesis were unchanged. In conclusion, our longitudinal study of men with chronic myeloid leukemia showed a significant, but largely transient, decrease in SHBG levels in response to imatinib therapy. Testosterone levels were low in the men both before and during imatinib therapy.

Proceedings of the 5th Copenhagen Workshop on Endocrine Disrupters: Ubiquitous endocrine disrupters and possible human health effects

This special issue of International Journal of Andrology contains the proceedings of the 5th Copenhagen Workshop on Endocrine Disrupters with the subtitle ‘‘Ubiquitous endocrine disrupters and possible human health effects’’, which took place during 20–22 May 2009. The focus of the meeting was on human health effects of endocrine disrupters present in the environment of our modern daily life with emphasis on reproductive effects but also in relation to emerging evidence of other effects. The workshop was the fifth in the series of successful meetings held at Rigshospitalet in Copenhagen since 2000. The aim of these meetings has from the beginning been to bring together leading scientists with different expertise to discus the latest aspects of endocrine disruption. This 5 meeting in the series once again succeeded in this aim and gathered highly engaged participants from multiple disciplines including basic science, toxicology, reproductive biology, endocrinology, immunology and epidemiology. This mixing of people with different backgrounds not only proved to be beneficial for the sharing of ideas and results but also for opening up for new collaborations across disciplines. This special issue contains papers from nearly all speakers of the meeting resulting in a collection of review papers and original studies representing state of the art within the field of endocrine disrupters and human health. To bring the readers a feeling for the discussions that followed each presentation, we have also included the edited comments from the audience after nearly all of the articles in this volume. All papers accepted for this volume have passed the ordinary peer review process of the Journal. The organization of the workshop was a group effort of many people at the Department of Growth and Reproduction but we would in particular like to thank Tina Tronier, Kathrine Hurtigkarl, Anette M. Pedersen, and Britt M. Christensen for their valuable assistance. We also would like to thank Vivien McGrath (Edinburgh) for excellent editorial assistance. Finally, we gratefully acknowledge the generous support from the Danish Ministry of Environment and the Danish Ministry of Health, which made the workshop and this publication possible.