Women with multiple sclerosis temporarily get much better when pregnant, and researchers now think they know why.
Pregnancy causes a downshift in a woman’s immune system, and it appears that this unintentionally improves symptoms associated with the autoimmune disorder MS, according to a new study published recently in the Journal of Neuroinflammation.
Previous research has shown that MS relapses decrease by 70% during the last third of pregnancy, researchers said. Other autoimmune diseases like rheumatoid arthritis also improve with pregnancy.
Nerve function in MS is hampered because the immune system starts attacking the fat that serves as an insulating sheath around nerve fibers. The nerves become inflamed, and this can lead to nerve damage.
But pregnancy is a very special condition when it comes to the immune system, the researchers noted.
The immune system is set up to defend against foreign substances, and half of a fetus’s genetic material comes from the father.
Despite this, the fetus is not rejected by the mother’s immune system due to a balancing act in which the system adapts during pregnancy to become more tolerant.
Researchers decided to look more closely at these changes brought on by pregnancy and why they might improve MS symptoms. This could lead to new, more effective treatment options for MS patients, most of whom deteriorate over time.
The researchers focused in particular on T cells, which play a key role in driving MS and also are important during pregnancy.
The new study compared 11 women with MS to seven women without MS, all of whom had blood samples taken before, during and after pregnancy.
The research team identified the genes that regulate the T cells and studied how they switch on and off at various points during pregnancy.
“What was possibly most striking is that we couldn’t find any real differences between the groups during pregnancy, as it seems that the immune system of a pregnant woman with MS looks roughly like that of a healthy pregnant woman,” said researcher Sandra Hellberg, an assistant professor at the Department of Biomedical and Clinical Sciences at Linkoping University in Sweden.
Pregnancy affects networks of interacting genes, researchers found, and these genes are to a large extent linked to MS and to important processes in the immune system.
The network of genes affected during pregnancy also included genes regulated by pregnancy hormones, mainly progesterone.
“The biggest changes happen in the last third of pregnancy, and this is where women with MS improve the most. These changes are then reversed after pregnancy at the point in time when there is a temporary increase in disease activity. It is important to stress that disease activity thereafter goes back to what it was prior to the pregnancy,” Hellberg said in a university news release.
Researchers are now testing various hormones in the lab in an attempt to mimic the effects observed in the study, to see if these can be part of a possible future treatment strategy.
Johns Hopkins has more about multiple sclerosis and pregnancy.
SOURCE: Linkoping University, news release, June 13, 2023
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