New Model Helps Scientists Study Mysterious Pain Condition that Prevents Women from Having Sex

Researchers have developed the first in vitro (translation: outside the body) model to study the enigmatic condition of vulvodynia, which triggers unexplained pain at the opening of the vagina and is the most common cause of intercourse pain in premenopausal women. There are no proven medical treatments for the disorder, which affects around 15 percent of women and girls of all ages and ethnicities, according to David C. Foster, M.D., M.P.H., a gynecologist and international vulvodynia expert. He is optimistic that the model will speed the evaluation and development of much-needed new therapies.

Vulvodynia is often diagnosed when a woman is treated for a series of yeast infections and continues to experience pain long after the infections have been cleared. It may also arise following other causes of genital irritation, such as treatment for genital warts or contact with a chemical allergen. Until now, the cause of the lasting pain women experience has been a mystery, leading some health care professionals to erroneously label vulvodynia a “psychological condition". 

Using the in vitro model, which incorporates cells from healthy and vulvodynia-afflicted women, Foster and a research team headed by co-lead investigator Richard P. Phipps, Ph.D. found that vulvodynia sufferers have a much stronger immune response to infection-causing yeasts compared to women without the disease. They believe that this overblown response leads to increased inflammation that promotes pain upon contact, like when having sex, inserting a tampon or wearing tight-fitting pants. It is not known why the pain persists: Foster says that genetics or an environmental trigger may cause certain women to develop chronic pain.

Foster and Phipps hope that exploring the cellular signaling mechanisms of the immune response will identify potential drug candidates that may turn in to new treatment options for this devastating condition, which strains relationships and hinders or completely eliminates the ability to conceive because couples can’t have sex.  

The research, published in the journal Pain, was funded by the Eunice Kennedy Shriver National Institute of Child Health and Human Development at the National Institutes of Health. Foster, professor emeritus in the Department of Obstetrics and Gynecology and Phipps, professor of Environmental Medicine, worked closely with Constantine G. Haidaris, Ph.D., professor in the Department of Microbiology and Immunology, Adrienne D. Bonham, M.D., M.S., clinical associate professor of Obstetrics and Gynecology and Christopher J. Stodgell, Ph.D., research associate professor of Obstetrics and Gynecology.

In an accompanying editorial, Melissa A. Farmer from the Feinberg School of Medicine at Northwestern University states, “I believe that the proof of concept of Foster et al. is one of the most significant advances in vulvodynia research over the past 20 years.”