Neuroinflammation in endometriosis: macrophages behaving badly?

Lead Research Organisation: University of Edinburgh
Department Name: MRC Centre for Reproductive Health

Abstract

Endometriosis is an inflammatory condition, defined by the presence of womb lining (endometrium) outside the womb, most commonly on the lining of the wall of the pelvic cavity ('endometriosis lesions'). This is thought to occur via a phenomenon known as 'retrograde menstruation', where the endometrium that is shed during menstruation is refluxed backwards through the Fallopian tubes into the pelvic cavity. Endometriosis affects approx.1.5 million women in the UK and a large majority of women with endometriosis also have debilitating pelvic pain. Costs incurred by treating women with endometriosis and associated loss of productivity are estimated at £11.7 billion per year. Endometriosis is treated surgically or with drugs that suppress hormones, but symptoms usually recur after surgery and the available medical treatments have undesirable side effects. Women want new treatments to ease their suffering.
Why endometriosis causes pain is poorly understood but I believe that it is due to the growth of new nerves into the lesions and their stimulation by molecules involved in inflammation (neuroinflammation). Notably, endometriosis can also be found associated with a general increased sensitivity to pain. Immune cells, such as macrophages are critical in the inflammatory process. Each tissue has its own 'type' of macrophage and they have been identified as important cells in the disease progression of endometriosis. We do not know how macrophages affect nerve growth in endometriosis or contribute to pain in the condition. However, I have recently shown that macrophages manipulated in the laboratory to mimic macrophages found in endometriosis lesions increase nerve growth and inflammation. I have developed a novel experimental mouse model of endometriosis that mirrors the human condition. The lesions form in a similar way to the human, and the mice also exhibit endometriosis-associated pain. Using this model I have shown that macrophages from the pelvic cavity migrate ino lesions. Notably, for the first time I have also shown that macrophages present in the shed endometrium at the time of menstruation also survive in the lesions. This model will allow me to determine how macrophages contribute to neuroinflammation, endometriosis-associated pain and subsequent increases in sensitivity to pain.
My specific aims are fourfold; firstly I will investigate how macrophages, that are present in the shed endometrium at the time menstruation, influence the formation of endometriosis lesions using a laboratory mouse model of 'menstruation' and endometriosis. Secondly, I will determine how macrophages influence nerve growth and neuroinflammation in endometriosis lesions. Thirdly, I will determine how factors produced by macrophages that have been identified in the previous objective, interact with nerves by using pain-sensing nerves grown in the laboratory. Finally, I will determine if macrophages play a role in endometriosis-associated pain and general increased sensitivity to pain, and to discover whether inhibition of factors produced by macrophages can reduce this pain.
I have developed innovative new models and produced exciting and informative novel preliminary data and I am confident that I can deliver the specified aims. I believe that information generated during this fellowship will lead to quality high impact publications, new understanding of how endometriosis causes pain and will inform new ways to treat endometriosis-associated pain.

Technical Summary

Endometriosis is a common chronic inflammatory disorder characterised by debilitating pelvic pain and hypersensitivity. Treatments are limited to hormonal suppression or surgical excision of lesions and symptoms commonly recur. There is an un-met clinical need for new strategies to treat endometriosis-associated pain. I believe that the pain is a consequence of neuroinflammation; the growth of new nerves and their activation by inflammatory mediators within the lesion. Endometriosis-associated macrophages are critical players in the pathophysiology of endometriosis. I have generated evidence indicating that isolated human M2 or 'regenerative' macrophages exposed to oestrogen to mimic the microenvironment of human endometriosis lesions both enhance neurogenesis and increase the expression of inflammatory cytokines. However, it is unknown how endometriosis-associated macrophages contribute to neurogenesis, neuroinflammation and pain in vivo. The objectives of this project are:
1. To use the macrophage depletion mouse, Cd11b-DTR to determine how macrophages present in the shed endometrium contribute to the establishment of lesions using a mouse model of 'menstruation' and a novel mouse model of endometriosis
2. To use the Cd11b-DTR mouse to determine how macrophages influence neurogenesis and neuroinflammation in established lesions in a mouse model of endometriosis.
3. To interrogate the effect of macrophage-derived factors identified in (2) on nerve function using in vitro models of sensory neurons.
4. To determine the role of macrophages in endometriosis-associated pain and hypersensitivity using behavioural monitoring in mice and to explore how inhibition of macrophage-derived factors ameliorate endometriosis-associated pain.
I am confident the work will generate novel data leading to high impact publications, significant advances in the field and the identification of novel targets with translational value for the treatment of endometriosis-associated pain.

Planned Impact

Benefit to patients and to the NHS:
Endometriosis UK (http://www.endometriosis-uk.org/) estimates that 1.5 million women in the UK suffer from endometriosis and associated debilitating pelvic pain. Endometriosis has a huge impact on their quality of life, ability to work and care for their families. The development of novel therapeutics that avoid the side-effects of current therapy options will greatly improve the health, quality of life and productivity of endometriosis patients. The costs associated with supporting patients places a significant economic burden on healthcare providers. The work described in this proposal represents an opportunity to advance understanding of the mechanisms of endometriosis-associated pain and a platform for development of a therapy that avoids surgery or contraceptive/menopausal side effects. We have established a network within Scotland (Scottish Endometriosis Network) who meet regularly to debate way(s) in which we can improve patient care and who will provide ongoing input into my research project. We have a close dialogue with patient organizations including Endometriosis UK (letter of support) to ensure the impact on patient care of any findings is maximized.
Benefit to commercial organisations:
Data generated will be of particular interest to commercial organizations because it will lead to an understanding of macrophage-derived factors involved in pain and hypersensitivity, identify novel targets and lead to the development of therapies that have an effect on the pain-regulatory cascade that accompanies this disorder. I have already built in a platform for commercialisation of the results obtained by working closely with the University of Edinburgh's BioQuarter Team, a realistic time-frame for this to be realised is 5-10 years.
Benefit to charities:
We work in close association with the charity Endometriosis UK. I am part of a team involved in disseminating information to patients at a recent patient information day hosted by the charity (April 2014). I will continue to work with Endometriosis UK to help healthcare providers and communicate my research to patients and their families. My co-sponsor Dr Andrew Horne also recently organised an event for endometriosis awareness at the Scottish Parliament with Endometriosis UK, and we received a statement from the Health Minister stating that funding should be allocated in this area.
Benefit to policy-makers:
Mounting evidence suggests endometriosis causes general hypersensitivity to pain due to changes that occur in the CNS of women with chronic pain. The proposed work will generate new knowledge on this and benefit policy makers, because it should inform alterations in the way patients are received in the clinic with more emphasis on input from pain psychologists, and pain experts. Dr Andrew Horne's Pelvic Pain Team is multidisciplinary, however this is not the case throughout the whole of the UK.
Benefit to wider public:
New treatments that arise as a result of the proposed programme of work will benefit members of the general public including the families, partners and employers of women with endometriosis.
Benefit to researchers and clinicians working in the field of pain and endometriosis:
Endometriosis remains an enigmatic disorder and its aetiology is poorly understood. I will publish my findings in high impact academic journals, share them via our website and communicate them at local and international meetings that attract experts in the field.
Benefit to capacity building:
The proposed work will allow me to launch my independent career and the work will involve training in new techniques. It will allow me to develop my own supervision and mentoring roles and offer the opportunity for both MSc and undergraduate medical students to undertake projects within the vibrant environment of the Institute. The research will generate a 4 year post for a UoE grade 6 technician providing job security and training.

Publications

10 25 50
 
Description Barbour Watson Trust- awarded to Chloe Hogg PhD student
Amount £2,000 (GBP)
Organisation University of Edinburgh 
Sector Academic/University
Country United Kingdom
Start 12/2017 
End 12/2018
 
Description Edinburgh Cellular Genomics Consortium Pump Priming Competition for scRNA-Seq (stemming from an MRC Discovery Award made to Prof Chris Ponting)
Amount £15,000 (GBP)
Organisation Medical Research Council (MRC) 
Sector Academic/University
Country United Kingdom
Start 01/2018 
End 06/2018
 
Description MRC Asset sharing
Amount £302,097 (GBP)
Organisation Medical Research Council (MRC) 
Sector Academic/University
Country United Kingdom
Start 01/2017 
End 12/2018
 
Description Project grant
Amount £40,000 (GBP)
Organisation Rosetrees Trust 
Sector Charity/Non Profit
Country United Kingdom
Start 04/2018 
End 02/2020
 
Description Research Incentives Grant
Amount £7,217 (GBP)
Funding ID 70354 
Organisation Carnegie Trust 
Sector Charity/Non Profit
Country United Kingdom
Start 01/2016 
End 12/2016
 
Description Research and Innovation Staff Exchange (RISE) Call: H2020-MSCA-RISE-2015
Amount € 45,000 (EUR)
Organisation European Commission 
Sector Public
Country European Union (EU)
Start 01/2016 
End 12/2020
 
Description Wellbeing of Women Research Grants
Amount £198,864 (GBP)
Organisation Wellbeing of Women 
Sector Charity/Non Profit
Country United Kingdom
Start 08/2016 
End 08/2018
 
Title in vivo optical imaging of endometriosis lesions in our in-house mouse model 
Description We have optimised our in-house model to allow non invasive optical imaging of endometriosis lesions allowing repeated measures and reduced numbers of animals 
Type Of Material Model of mechanisms or symptoms - mammalian in vivo 
Year Produced 2017 
Provided To Others? No  
Impact Reduced numbers of animals 
 
Description Optimisation of the Edinburgh Mouse Model of Endometriosis 
Organisation Ferring Pharmaceuticals
Country Switzerland 
Sector Private 
PI Contribution My research team and I are contributing expertise, intellectual input and animal modelling skills to the collaboration in order to optimise our in-house mouse model of endometriosis to allow non-invasive optical imaging of lesions and maximise the use of the model for testing potential therapeutics. Our research has led to a number of important insights and we have achieved the objective of modifying the model to allow imaging. Ferring have since extended our initial collaboration from 6 months to 18 months in order for us to investigate molecular mechanisms of endometriosis development in the hope of identifying new targets.
Collaborator Contribution The collaborators are contributing their expertise and intellectual input in how the model might be used for testing therapeutics
Impact Not yet
Start Year 2017
 
Description 'miRNAs in Endometriosis' conference (Germany) 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact 50 delegates attended 'miRNAs in endometriosis' in Münster, my talk sparked a lot of interest in my novel mouse model of endometriosis and some new collaborations may arise from this.
Year(s) Of Engagement Activity 2017
 
Description Come and meet the EXPPECT team and learn about endometriosis 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Patients, carers and/or patient groups
Results and Impact I organised a workshop for patients as part of the MRC festival. The event consisted of talks, laparoscopy simulators, chance to look at lesions down the microscope and learn about endometriosis research. We had very good feedback from attendees who wanted more events like this.
Year(s) Of Engagement Activity 2017
 
Description Endometriosis-associated macrophages; defining their functions and ontogeny. Biomedical Research Unit in Reproductive Health, University of Warwick - invited speaker 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Postgraduate students
Results and Impact 40 people attended this invited seminar which encouraged lots of discussion and plans for collaboration
Year(s) Of Engagement Activity 2017
 
Description Exploring pain mechanisms in endometriosis. Centre for Discovery Brain Sciences, University of Edinburgh - invited speaker 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Postgraduate students
Results and Impact 50 researchers attended this invited seminar, which sparked questions and discussion and increased awareness of the condition
Year(s) Of Engagement Activity 2017
 
Description Interview for New Scientist 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact Provided journalist from New Scientist with opinion on endometriosis research
Year(s) Of Engagement Activity 2017
URL https://www.newscientist.com/article/2153750-common-condition-endometriosis-reprograms-brain-for-dep...
 
Description Laboratory models for identifying new drug targets for endometriosis. ESHRE, Helsinki, Finland - invited speaker 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact ESHRE Pre- Congress Course 7 Endometriosis - getting research from bench to bedside, Helsinki, Finland. Over 100 researchers from academia, clinical practice and Industry attended this pre-congress course where I was an Invited speaker. Ferring Pharmaceuticals first approached me following this talk - led to a collaboration.
Year(s) Of Engagement Activity 2016
 
Description Royal College of Obstetricians and Gynaecologists Annual Academic Meeting - invited speaker 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Professional Practitioners
Results and Impact Communicating translational basic science research to clinicians. Generated lots of discussion about the direction of endometriosis research
Year(s) Of Engagement Activity 2016
 
Description Society for Reproductive Investigation Annual Conference (California) 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Other audiences
Results and Impact Poster presentation of recent research, sparked questions and discussion, interest from industry and attracted a New Investigator Award
Year(s) Of Engagement Activity 2015
URL http://www.sri-online.org/about-sri/sri-awards/2015-best-new-investigator-posters
 
Description What can be learnt from murine models? ESHRE Campus Course; Methodological approaches for investigating endometrial function and endometriosis, Edinburgh, UK - invited speaker 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Over 100 researchers attended this campus course to learn more about methods for studying endometrial function and endometriosis
Year(s) Of Engagement Activity 2017