Why does pregnancy sometimes reduce relapses in people with MS?

People with relapsing remitting MS who become pregnant often experience reduced relapse rates, especially during months seven to nine. After birth, relapse rates often return to normal or can even be worse. If we can understand why this occurs naturally in pregnancy, then we might be able to develop this as a new therapy for all people with MS.

About the project

The aim of this project is to better understand the effects of pregnancy on MS. During pregnancy, small fragments known as extracellular vesicles (EVs) are released from the placenta into the mother’s bloodstream. These EVs are packages which carry a cargo of molecules. The amount of EVs released by the placenta increases throughout pregnancy.

The team think these placental EVs travel in the bloodstream to the brain, where they deliver their cargo. They think the cargo in the EVs could reduce inflammation in the brain and so decrease the immune attacks in MS.

To test this, they’ll collect EVs in blood samples taken from pregnant people, both with and without MS. They’ll compare number, size, and the cargo inside, to see if the EVs from people with MS are different. Then, they’ll add the EVs to immune cells in a dish to see whether the effects are different.

How will it help people with MS

In the future the team hope to develop a therapy using placental EVs which would reduce relapses similarly to pregnancy. This would benefit people living with MS as a treatment option.

Understanding the link between pregnancy and reduction in relapses will lead to further findings. For example, not all pregnant people with MS experience a reduction in relapses. This could be linked to differences in their EVs. So, EVs could help to predict how an individual with MS might respond to pregnancy and help inform decisions around pregnancy and treatments.