Perinatal origins of male reproductive health disorders

Lead Research Organisation: MRC Human Reproductive Sciences Unit

Abstract

Reproductive disorders in newborn boys (incomplete testicular descent into the scrotum, hypospadias - a disorder of penis development) and young men (low sperm counts, testicular cancer) are extremely common and/or may be increasing in incidence. Many cases of these disorders probably arise because of abnormal development of the testis in the fetus during early pregnancy, and in animal models we have recently identified when and how this is likely to occur, although we still do not know what causes the problems in humans. It appears to involve abnormal development of key cell types in the fetal testis and altered male sex hormone (testosterone) production/action.||We have established an animal model in which very similar disorders can be induced in the male offspring after exposure of the mother during pregnancy to a common environmental chemical (dibutyl phthalate, DBP). We are using this model to establish the mechanisms in the fetal testis via which the subsequent male reproductive disorders arise, and so identify potential causal routes.||To be fertile, a man must produce tens of millions of sperm every day. A low sperm count can lead to impaired fertility. The number of sperm a man can make is determined by numbers of the supporting (Sertoli) cells in his testes, as these cells regulate sperm production. Sperm counts and Sertoli cell number vary enormously between men, and this variation may originate in fetal and early postnatal life (0-6 months of age), when Sertoli cells increase in numbers.||Recent findings have shown that testosterone produced within the developing testes, and which controls male development, also regulates Sertoli cell numbers. We are using animal models to establish the importance of this effect of testosterone, how it exerts its effects on Sertoli cells and whether deficiencies in its action result in infertility.||We will also investigate how certain environmental chemicals, including phthalates such as DBP, affect Sertoli cell development in these animal models, in order to understand how such exposures could reduce Sertoli cell numbers and lead to lower sperm counts or other male reproductive disorders in adulthood.

Technical Summary

Reproductive disorders in newborn boys (testicular maldescent, penile abnormalities such as hypospadias) and young men (low sperm counts, testicular germ cell cancer) are common. There is growing evidence that many cases of these disorders comprise a testicular dysgenesis syndrome (TDS) with a common fetal origin associated with maldevelopment of the fetal testis and of the functions of its Leydig and/or Sertoli cells.||We are using an animal model of TDS involving exposure of pregnant rats to the plasticizer dibutyl phthalate (DBP). Male DBP-exposed offspring exhibit a high incidence of cryptorchidism, hypospadias and infertility in adulthood and abnormal development/function of the germ cells and somatic (Leydig, Sertoli) cells in fetal life. The latter manifest as suppressed testosterone levels, altered Leydig cell development, reduced Sertoli cell number and abnormalities in fetal germ cells. Focal dysgenetic changes in the testes of DBP-exposed males are evident in adulthood (malformed seminiferous cords, intratubular Leydig cells, Sertoli cell-only tubules, immature Sertoli cells), which we have also found in testes of adult human TDS patients.||We are using the rat TDS model and testis tissue from humans and marmosets to establish the cellular, biochemical and hormonal mechanisms via which TDS disorders arise, by characterising functional development of fetal (and postnatal) Leydig, Sertoli, germ and peritubular cells, using confocal microscopy, immunocytochemistry, Westerns and RT-PCR. Similar approaches are being applied to fixed/cultured testis tissue to compare somatic and germ cell development in the human, marmoset and rat.||Related studies are focused on low sperm counts in men, which can cause infertility, and which is common e.g. 15% of young Scottish men in our studies have abnormally low sperm counts. Other than abstinence period, the key determinant of sperm counts is the number of Sertoli cells in the testes, which is determined by their proliferation in fetal, neonatal and peripubertal life. Variation in Sertoli cell number and sperm counts between men is huge, but what causes this variation is unknown. We have shown in our animal models (transgenic mice, rats, marmosets) that testosterone action in fetal and early postnatal life is important in increasing Sertoli cell numbers, and we are using these to establish what factors relevant to humans might reduce androgen-driven Sertoli cell proliferation in fetal or neonatal life and thus affect sperm production/fertility in adulthood.||Using our animal models, we have identified a masculinisation programming window in fetal life during which androgens must act to enable correct later development of the reproductive system. We have shown that impaired androgen action within this discrete time window induces cryptorchidism and hypospadias, determines adult testis size (and thus sperm counts) as well as penis and prostate size and anogenital distance. The latter provides a lifelong read-out of androgen action within the masculinisation programming window. The latter is thus a likely time in fetal life for the origin of TDS disorders.

Publications

10 25 50

 
Description Advisory Committee on Hazardous Substances
Geographic Reach National 
Policy Influence Type Gave evidence to a government review
Impact Provided research evidence as a foundation for policy decisions to be made
 
Description British Nutrition Foundation task force report on 'Nutrition and developmental programming of later disease
Geographic Reach National 
Policy Influence Type Participation in a advisory committee
URL http://eu.wiley.com/WileyCDA/WileyTitle/productCd-1444336789,descCd-buy.html
 
Description Co-writer of report prepared for the European Science Foundation on Male reproductive health
Geographic Reach Europe 
Policy Influence Type Participation in a advisory committee
URL http://www.esf.org/publications/medical-sciences.html
 
Description Gave 1h web-casted presentation to US Consumer product safety commission: chronic hazard advisory panel (CHAP).
Geographic Reach North America 
Policy Influence Type Gave evidence to a government review
Impact The CHAP committee reports directly to the US Government and determines regulatory policy on the use of, and human exposure to, phthalates, which are ubiquitous environmental chemicals.
URL http://www.cpsc.gov/about/cpsia/chap1111.html
 
Description Invited external expert reviewer for the US Department of Health & Human Services National Toxicology Program
Geographic Reach North America 
Policy Influence Type Participation in a advisory committee
Impact Provided objective analysis of the potential impacts of exposure to bisphenol A on the risk of disease in humans
 
Description Member of the Veterinary Products Committee working group on 'Risks associated with the use of hormonal substances in food-producing animals'.
Geographic Reach Multiple continents/international 
Policy Influence Type Participation in a advisory committee
 
Description Member of the working group on Variability and uncertainty in toxicolocy for the UK Committee on Toxicity
Geographic Reach National 
Policy Influence Type Participation in a advisory committee
 
Description Royal Society of Chemistry's Toxicology Group & Environment & Health Safety Committee
Geographic Reach National 
Policy Influence Type Participation in a advisory committee
 
Description WHO/FAO expert assessment of health risks of bisphenol A
Geographic Reach Multiple continents/international 
Policy Influence Type Participation in a advisory committee
Impact Expert assessment and report that will guide regulatory decisions by governments worldwide as well as framing research priorities for the future
 
Description BBSRC CASE Studentship
Amount £72,000 (GBP)
Organisation Biotechnology and Biological Sciences Research Council (BBSRC) 
Sector Public
Country United Kingdom
Start 09/2006 
End 08/2009
 
Description EU Framework V
Amount £264,000 (GBP)
Organisation European Commission 
Department Fifth Framework Programme (FP5)
Sector Public
Country European Union (EU)
Start 01/2006 
End 04/2006
 
Description EU Framework VII
Amount £403,850 (GBP)
Organisation European Commission 
Department Seventh Framework Programme (FP7)
Sector Public
Country European Union (EU)
Start 05/2007 
End 04/2011
 
Description ICCA, Long Range Research Initiative
Amount £36,050 (GBP)
Organisation International Council of Chemical Associations (ICCA) 
Sector Academic/University
Country Global
Start 06/2008 
End 03/2009
 
Description Project grant
Amount £16,000 (GBP)
Organisation Wellcome Trust 
Sector Charity/Non Profit
Country United Kingdom
Start 04/2008 
End 03/2011
 
Title Animal model of human disease 
Description It is an animal model for the commonest human male reproductive disorders that affect newborn and young adult males, disorders that are collectively referred to as testicular dysgenesis syndrome (TDS). We developed and validated this model, based on first reports from toxicologists. It enables study of some of the mechanisms that lead to TDS disorders, which is not possible directly in the human. It involves pregnancy exposure of laboratory rats to a ubiquitous environmental chemical, dibutyl phthalate (DBP), and therefore offers opportunities to also evalaute if this compound (or like compounds) may contribute causally to human TDS disorders. 
Type Of Material Model of mechanisms or symptoms - mammalian in vivo 
Year Produced 2006 
Provided To Others? Yes  
Impact Description and further use of this model has been widely accepted as validating the TDS hypothesis in humans. It has identified potential new mechanisms underlying TDS disorders, including effects of deficient androgen production/action on Sertoli cells (the cellular orchestrators of normal testis development), transient effects on early fetal testis growth and delays in cell development and differentiation. It has emphasised the importance of normal timing of fetal testis development as a determinant of normal reproductive function in later life. 
 
Title Xenografting of human fetal testis tissue 
Description Xenografts of human fetal testis tissue are grafted into immune-compromised mice and then grow normally, providing a model system for directly investigating what chemicals/other factors may adversely impact on human fetal testis development and function 
Type Of Material Model of mechanisms or symptoms - human 
Provided To Others? No  
Impact Allows for the first time 'experimentation' on the human fetal testis whilst it is growing and developing normally. Provides a direct means for assessing risks of chemicals to this tissue in fetal life, which has previously been impossible 
 
Description Androgen action in the testis 
Organisation Catholic University of Louvain
Country Belgium 
Sector Academic/University 
PI Contribution We utilised tissues from animals provided by our collaborators to explore the role of androgen in fetal testis development
Collaborator Contribution They generated specific androgen receptor knockout mice which we used for some of our studies
Impact Publications 17289843 19131576 19587329 19587329
 
Description Biomarkers of testicular toxicity 
Organisation GlaxoSmithKline (GSK)
Country Global 
Sector Private 
PI Contribution We undertook the majority of the research
Collaborator Contribution It has explored the possibility of in-life assessment of early adverse toxic effects on the testis using germ cell-specific biomarkers, and shown that this is not a realistic possibility.
Impact Thorough investigation of this possibility. 20624998
Start Year 2006
 
Description EU Framework V - EDEN partnership 
Organisation Rigshospitalet
Country Denmark 
Sector Hospitals 
PI Contribution We have developed, validated and applied animal models for the relevant human diseases (testicular dysgenesis syndrome) and this has provided new understanding and targets for the corresponding clinical studies.
Collaborator Contribution It has provided clinical data on patients that complements our animal model based studies to make a cohesive research programme
Impact New understanding of the origins of common human male reproductive disorders 16466534 16916955 17289843 17431488 17877717 17928633 18174951
 
Description EU Framework VII 
Organisation University of Turku
Department Department of Physiology
Country Finland 
Sector Academic/University 
PI Contribution Further development and refinement of our animal models to enable uncovering of the mechanistic basis for the fetal origins human testicular dysgenesis syndrome disorders and how these may relate to wider disruption of health, such as metabolic disorders.
Collaborator Contribution Provision of prospective clinical studies of human males with/without relevant male reproductive disorders and evaluation of the role that perinatal exposures to environmental chemicals may have on this. This integrates with our similar, mechanistic animal-based studies.
Impact New understanding of the origins of common human male reproductive disorders 18308057 18566125 19656234 19819957 20002220
Start Year 2007
 
Description Effect of fetal exposure of sheep to environmental chemicals on development and fucntion of the reproductive system 
Organisation University of Aberdeen
Department Biomedical Sciences
Country United Kingdom 
Sector Academic/University 
PI Contribution Responsible for evaluating effects on the developing testis and male reproductive tract
Collaborator Contribution It has provided an additional animal model in which exposure to complex 'real world' mixtures of environmental chemicals can be evaluated for their effects on the developing reproductive system. This complements our laboratory-based animal studies.
Impact New evidence for effects of fetal chemical mixture exposure on all different component parts of the reproductive system (brain, gonads and hormones). 18436539 20019906 20236231 20582145 20676422
Start Year 2007
 
Description Susceptibility of fetal testis steroidogenesis to disruption 
Organisation International Council of Chemical Associations (ICCA)
Country Global 
Sector Academic/University 
PI Contribution We undertook the literature research and the writing of the review
Collaborator Contribution It enabled the writing and publication of a major review article, which would not otherwise have been possible.
Impact Publication of the review 19887492
Start Year 2008
 
Description British Science Festival 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Public/other audiences
Results and Impact I gave a presentation on 'Use of xenografts of human fetal testis tissue for identifying the fetal origins of male reproductive disorders' as part of a symposium on 'animals containing human material' in research, organised by the Academy of Medical Sciences, and on which they have since published a report (ISBN: 978-1-903401-32-3)

Coverage in the media, filmed interview (available on Youtube) as well as the report by Academy of Medical Sciences mentioned above
Year(s) Of Engagement Activity 2010
 
Description CBS News 60 minutes feature 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Type Of Presentation Keynote/Invited Speaker
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact CBS News 60 minutes programme on 'Phthalates: are they safe?' (2010)

Invitations from the plastics industry to talk to them at their scientific meetings
Year(s) Of Engagement Activity 2013
URL http://www.cbsnews.com/video/watch/?id=6512528n&tag=api
 
Description Interactions with the media 
Form Of Engagement Activity A magazine, newsletter or online publication
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Media (as a channel to the public)
Results and Impact On google, I have 71 listed hits for media interactions/stories since 2006 and these are summarised, and the more important itemised, below. Television appearances/interviews for Danish television news (2007) and a Danish documentary (2006), for the main Science news programme in Norway and for a documentary shown recently in Sweden & Norway (June 2009) on prime-time evening TV (http://www1.nrk.no/nett-tv/klipp/503455). Also participated (filmed interviews in Copenhagen and my laboratory) in a Franco-German production 'Men in Danger', a documentary (http://www.filmakers.com/index.php?a=filmDetail&filmID=1558) screened in France and Germany in 2008 and which won best current affairs program, Prix Europa 2008. Also filmed interview for UK (international) production of 'Toxic baby' which is due for public release or screening in 2009-2010 (http://www.toxicbaby.com/). Recently did filming/interview in my lab for CBS News 60 minutes on environmental chemicals and how to assess human health risks, due for screening in Autumn 2009. Numerous radio interviews for UK - BBC News or World service (8 times), BBC Radio Scotland, Radio 4, several local radio stations and for abroad (have done live interviews with local radio stations in Australia, USA and Canda in the last two years). Numerous interviews for UK newspapers - Scotsman, Daily Mail (several times, most recently in 2012), Daily Express, The Times (several times, most recently in 2012), Sunday Times (several times, most recently in 2012), Telegraph (several times, most recently in 2012), Independent (several times, most recently in 2012), Guardian. Also interviews for magazines - Nature, New Scientist, Mens Health (twice), Marie Claire, Playboy and others whose names I've forgotten - and for independent journalists.

Continued media and public interest in matters relating to male reproductive health. Repeated contacts by journalists, the Science media Centre, Sense about Science etc
Year(s) Of Engagement Activity 2006,2007,2008,2009,2010
URL http://www1.nrk.no/nett-tv/klipp/503455
 
Description Presentation to industry 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact I gave a talk and was the Workshop summariser at the European Council for Plasticisers and Intermediates (ECPI) Workshop on Phthalate Esters & Reproductive Health

This has led to ECPI funding a series of studies in academic laboratories to help address the concerns and uncertainties raised at this workshop
Year(s) Of Engagement Activity 2006
 
Description Public engagement committee 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? Yes
Geographic Reach National
Primary Audience Public/other audiences
Results and Impact Committee set up by the Society to better inform the public about all aspects of endocrinology and its health relevance by sponsoring public talks at UK Science Festivals and by engaging with and interacting with all aspects of the media.

Widespread sponsoring of public lectures at UK Science Festivals. Considerable coverage of these talks in the media.
Year(s) Of Engagement Activity 2008,2009,2010,2011
 
Description Public lecture 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? Yes
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact I gave a talk on: How hormones rule our lives: effects of hormones from within and outside the body

This was an inaugural talk in this series which prompted the Society to extend these public lecture/communication activities by sponsoring public talks at UK Science Festivals and by forming a Committee to identify, implement and co-ordinate these activities
Year(s) Of Engagement Activity 2007
 
Description Public lecture 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? Yes
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact I gave a talk on: How hormones rule our lives.

Coverage in local media and in UK Society for Endocrinology newsletter (they co-sponsored the talk).
Year(s) Of Engagement Activity 2008
 
Description Public lectures 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? Yes
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact I presented two public lectures in 2008 as part of the ongoing series (attended by general public + schoolchildren). They were as follows: 1. Why testicles are cool 2. Who's in control? How hormones rule our lives from start to finish

More interest in our research (local media coverage) plus attendees have returned to attend most public lectures in this series since then.
Year(s) Of Engagement Activity 2008
 
Description Sense about Science 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? Yes
Geographic Reach National
Primary Audience Media (as a channel to the public)
Results and Impact Member of expert panel for Sense about Science which provides expert assessment of new scientific publications/research for the media in the UK and which is intended to reinstate more balance in media science reporting in the UK

Continued use by the media of quotes/analyses that I provide via Sense about Science
Year(s) Of Engagement Activity 2006,2007,2008,2009,2010