A UCLA study reveals the cellular basis for how estrogen protects against damage to the central nervous system in women with multiple sclerosis. The researchers found estrogen treatment exerts positive effects on immune cells in the brain and in oligodendrocytes.

The third trimester of pregnancy has been shown to reduce relapse rates by about 70 percent as compared to before pregnancy. Other studies have shown benefits over the long term because of multiple pregnancies. An estrogen unique to pregnancy that is made by the fetus and placenta has been proposed by researchers to mediate this pregnancy protection in both the MS mouse model as well as in two successfully completed clinical trials of estriol treatment in women with MS. How that happens has remained a critical question. Researchers have reported mouse studies showing that estrogen protected the brain from damage by activating a protein called estrogen receptor beta.

Researchers used female mice genetically engineered to show MS symptoms. They first eliminated the estrogen receptor beta in either immune cells of the brain or in oligodendrocytes, the cells that make the myelin sheath, as a way of making those particular cells unresponsive to estrogen. They then treated mice without or with the estrogen receptor beta in these cells to learn if disease protection was lost or not. Results showed that the estrogen-like treatment was acting on both immune cells of the brain as well as on oligodendrocytes, together resulting in myelin repair and reduced disability.

Results of mouse model studies sometimes do not translate to humans and may be years away from being a marketable treatment. However, the researchers said this study confirms that this estrogen-like compound can combat MS via complementary effects on two distinct cell types. Researchers are now developing a next-generation estrogen-like compound with robust biochemical effects on oligodendrocytes and immune cells in the brain.

The study was published in the journal Brain.