There is a growing body of scientific evidence suggesting that hormones, including sex hormones, may affect and be affected by the immune system. For example, both estrogen and progesterone, two important female sex hormones, may suppress some immune activity. Testosterone, the primary male hormone, may also act as an immune response suppressor. During pregnancy, estrogen and progesterone levels are very high, which may help explain why pregnant women with MS usually have less disease activity.
Laboratory Studies Suggest Role of Sex Hormones
Manipulation of sex hormones in animal models of MS and some other autoimmune diseases has been shown to prevent or ameliorate these diseases. To address this question, the National MS Society convened a Task Force on Gender, MS and Autoimmunity, which recommended that:
- The immune responses of men and women be studied comparatively
- The interaction of all hormones with the immune system be studied in both men and women
- A comparison study of menstruation, pregnancy and menopause be made in women with MS and other autoimmune diseases
- A study of genetic factors be made to determine whether gender-related autoimmune responses are inherited
- A study be made of differences in the disease course between men and women
Sex Hormones as Treatments for MS
Both testosterone and estriol—an estrogen hormone that is produced during late pregnancy—have been shown to have a beneficial effect in experimental allergic encephalomyelitis (EAE), the animal model of MS. Based on these findings, Rhonda Voskuhl, MD, and colleagues conducted a small trial of estriol in women with MS.
Estriol appeared to reduce MRI activity in women with relapsing remitting MS, but not in those with secondary progressive MS. Dr. Voskuhl is now leading a team of investigators at seven medical centers to conduct a two-year, controlled clinical trial of estriol added to standard therapy to treat MS. Investigators plan to administer either oral estriol along with Copaxone® (glatiramer acetate, Teva Pharmaceutical Industries Ltd.) or Copaxone plus inactive placebo to 150 women with relapsing-remitting MS. If successful, this clinical trial could lay the groundwork for a larger, definitive trial that could lead to a new treatment option for women with MS.
Nancy Sicotte, MD, Rhonda Voskuhl, MD, and colleagues have published results from a small study, funded by the National MS Society and others, suggesting that one year of treatment with a gel containing the sex hormone testosterone (applied to the skin) in 10 men with relapsing-remitting MS resulted in significant improvements in cognitive function and in slowing brain tissue loss. These positive findings were reported in the May 2007 issue of Archives of Neurology.
Impact of Hormones on Disease Onset or Progression in Women
There have been no large-scale studies of the effects of oral contraceptives or hormone replacement therapy in women with MS who are post- menopausal. The effects of such hormonal therapies on MS are unknown. One study has suggested that the use of oral contraceptives by women has no effect on the expected rate of developing MS.
MS and Fertility
To date, there is no evidence that either women or men with MS have lower fertility than age-matched healthy controls.