Scientists discover key cause of pain for women with endometriosis

Scientists have discovered a key cause for pelvic pain experienced by women with endometriosis, potentially leading the way for new kinds of pain relief for the condition.

Researchers have discovered how cells in our immune system play a role in stimulating the growth and activity of nerve cells in endometriosis, increasing women’s sensitivity to pain in the pelvic region.

The work was conducted at the Greaves lab at Warwick Medical School at the University of Warwick, along with collaborators at the University of Edinburgh.

While the actual cause of endometriosis is unknown, it occurs when cells in the internal lining of the uterus grow outside of it in the form of lesions, causing significant pelvic pain. Current treatment options are limited to surgical removal of lesions or medical management to suppress ovarian hormone production, with new non-hormonal treatments desperately needed.

The new research focuses on the role of macrophages in contributing to the pain caused by endometriosis. Macrophages, which are a type of white blood cell found in our immune system, can adapt according to local signals and become modified by disease. The research also showed that macrophages are drawn more to the endometriosis lesions and are also found in high numbers inside the lesions themselves.

The scientists used a cell culture of disease-modified macrophages to observe increased production of the insulin-like growth factor-1 (IGF-1). After applying this onto nerve cells grown in culture, the team found that this encouraged the nerves to grown and also activated them. This confirmed that the production of IGF-1 by macrophages plays an important role in generating pain in endometriosis.

The team also examined peritoneal fluid from women with endometriosis and found increased concentrations of IGF-1 compared to those without the condition.

While previous studies have shown the role macrophages play in chronic pain but this research is the first to link them to endometriosis.

Lead author Dr Erin Greaves from Warwick Medical School said: “Endometriosis is sometimes considered a ‘hidden disorder’ because of a reluctance to discuss what can be passed off as ‘women’s problems’. Hormonal solutions rely on suppressing ovarian function but are not ideal as they can cause unwanted side effects, and prevent the user from becoming pregnant. We are trying to find non-hormonal solutions.

“If we can learn about the role of macrophages in endometriosis then we can distinguish them from healthy macrophages and target treatment to them. Macrophages are so crucial to our immune system tissue function and we need to know more about their roles, so this research goes some way in defining how macrophages are different in endometriosis.”

The role of macrophages play in increasing sensitivity to pain in the body could also act as a potential marker to target for treatment, the research suggests.

Dr Greaves added: “Endometriosis can affect women throughout their lives and is a very common condition. This discovery will go some way towards finding ways to relieve symptoms for women who suffer from endometriosis. We hope that in the future we can learn exactly how disease-modified macrophages in endometriosis promote disease and how we can target them in order to treat endometriosis.”