During pregnancy, changes in the immune system have beneficial effects on the symptoms of multiple sclerosis.
- Pregnant women with multiple sclerosis usually notice a reduction in their symptoms.
- This is linked to changes in the immune system, which becomes more “tolerant” during this period.
- This would have effects on gene networks involved in the disease.
110,000 people suffer from multiple sclerosis in France, and the majority are women. Indeed, the latter have a greater risk of developing the disease. However, in case of pregnancy, there is a good chance that their symptoms will temporarily improve. Swedish researchers have just understood why and explain it in Log of Neuroinflammation.
Pregnancy: how does the immune system adapt?
“Pregnancy is a very special condition from an immunological point of view., they recall. Initially, our immune system has the role of protecting us against foreign elements present in our body, such as viruses or bacteria. “Although half of the fetus’ genetic material comes from the father, it is not rejected by the mother’s immune systemnote the authors. One of the reasons this balance exercise is almost always successful is that during pregnancy the mother’s immune system adapts to become more tolerant..”
However, multiple sclerosis (MS) is an autoimmune disease: this means that the immune system attacks the cells of our body. “The autoimmune mechanisms involved attack the myelin sheath that surrounds the axons in the central nervous system, explain Inserm. This phenomenon leads to scattered lesions in the central nervous system, called plaques: this is where the name of the disease comes from (the term sclerosis is historical and proves to be unsuitable).” According to researchers from the University of Linköping, this greater tolerance of the immune system during pregnancy could explain the reduction in MS symptoms.
MS: how does a woman’s immune system work during pregnancy?
“Periods of symptoms, i.e. relapses, decrease by 70% during the last third of pregnancy”, they explain. To better understand this phenomenon, the researchers looked at T lymphocytes, which are strongly involved in the immune system. In their study, they compared 11 women with MS to 7 healthy women through their blood test. “What was perhaps most striking was that we found no real difference between the groups during pregnancy, as it appears that the immune system of a pregnant woman with MS looks much the same as of a healthy pregnant woman“, explains Sandra Hellberg, one of the co-authors of the study. In reality, it is gene networks that are affected during pregnancy. The study shows that these genes “are largely related to disease and important immune system processes”.
For the authors of the study, these discoveries could lead to new treatments: they are currently testing the effects of different hormones in the laboratory. The latter could make it possible to mimic the effects of pregnancy on the immune system and thus reduce the symptoms of the disease.