UCLA Health researchers have received $7.5 million to renew its longstanding research center focused on sex differences in irritable bowel syndrome (IBS).
The five-year study will determine why women with irritable bowel syndrome experience more severe symptoms and a greater burden of symptoms than men. These symptoms go beyond the gut and can include migraines, muscle pain, anxiety and fatigue. Researchers will also test whether a non-invasive vagus nerve stimulation therapy could alleviate these symptoms.
The center is part of the National Institutes of Health’s Specialized Centers of Research Excellence (SCORE) on Sex Differences program, which supports research to better understand biological differences between women and men and improve women’s health. The five-year study is funded by the National Institutes of Health’s Office of Research on Women’s Health and National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) and overseen by three leading UCLA Health digestive diseases and brain-gut-microbiome researchers: Drs. Lin Chang, Elaine Hsiao and Emeran Mayer.
Irritable bowel syndrome (IBS) is a common gut disease affecting roughly 6-8% of adults in the U.S. IBS is associated with recurring abdominal pain or discomfort, bloating, diarrhea and/or constipation among others. Women with IBS are more likely to report more severe symptoms such as bloating, constipation and abdominal pain, compared to men, and are more likely to seek healthcare for them, according to a UCLA study published this year.
In the new study, the UCLA researchers will investigate whether differences in how the body responds to stress help explain this greater burden. They will study how stress responses interact with sex hormones, gut microbes and the nerves that carry signals between the gut and brain. This research could help identify treatments that address the broader range of symptoms experienced by people with IBS.
There are three interrelated projects. The first project, led by Chang and UCLA gastroenterologist Dr. Andrea Shin, will study how stress responses, hormones and gut microbes relate to symptoms in women and men. It will also test whether noninvasive stimulation of the vagus nerve, which connects the brain and gut, can ease IBS and accompanying symptoms.
The second project, led by Mayer along with Jennifer Labus and Arpana Church of UCLA Health, will use brain imaging to examine sex differences in how the brain processes stress and pain, and how these patterns change with vagal nerve stimulation.
The third project, led by Hsiao, will use experimental models to determine how gut microbes and biological sex causally influence neuronal signals involved in abdominal pain and anxiety, potentially identifying new treatment targets.
Three research cores will support the projects. The Analytical Core will measure sex hormones in blood and stool to help explain their role in IBS. The Leadership Administrative Core will coordinate the research and oversight. The Career Enhancement Core will provide training, mentoring and seed funding for researchers studying sex differences and women’s health, and share findings with the public.
The study is set to conclude in 2031.
