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According to a Swiss team, multiple sclerosis is caused by a lack of communication of immune cells, independently of genetic factors. A promising avenue for better understanding the origin of this disease and better treating it in the future.
A chronic inflammatory disease of the central nervous system, multiple sclerosis (MS) is also the most common cause of neurological impairment in young adults. It attacks the brain and spinal cord, causing various motor, cognitive and sensory disorders.
Unknown causes of multiple sclerosis
The cause of multiple sclerosis is still not officially known. Various genetic factors are suspected, as are different environmental influences, which have been associated with the disease. Last January, an American study had linked this disease to the Epstein-Barr virus, showing that the infection multiplied the risk of being affected by 32! But a new Swiss study sheds new light on the causes of this disease.
American researchers have endeavored to identify the genetic and environmental role in the occurrence of multiple sclerosis. According to them, genetic predisposition alone cannot explain MS. “Based on our study, we were able to show that approximately half of the composition of our immune system is determined by genetics.“, explains Florian Ingelfinger, doctoral student at the Institute of Experimental Immunology of the University of Zurich. The study carried out by the scientists shows that these genetic influences, although present in affected patients, are not sufficient on their own to trigger multiple sclerosis.
61 pairs of twins observed
Their study involved pairs of monozygotic twins, with only one twin having MS. These “identical twins” had the same genetic heritage. “Although the healthy twins also had the highest genetic risk for MS, they showed no clinical signs of the disease.”explains Lisa Ann Gerdes, co-author of the study.
Studying the occurrence of the disease in “identical twins” has enabled the team to rule out genetic influence and specifically monitor changes related to environmental factors. They focused on the impact on this impact on the immune system responsible for triggering MS in one of the two twins.
Updated immune system changes
“We explore the central question of how the immune system of two genetically identical individuals results in significant inflammation and massive nerve damage in one case, and no damage in the other.“, explains Burkhard Becher.
Relying on state-of-the-art techniques to describe in detail the immune profiles of twin pairs (mass cytometry, genetic analysis, artificial intelligence to sort information…), the researchers collected “as much information as technically possible from these valuable samples“.
An error in immune cell communication
“Surprisingly, we found that the biggest differences in the immune profiles of twins with MS are in cytokine receptors, that is, how immune cells communicate with each other. The cytokine network is like the language of the immune system.”says Dr. Ingelfinger.
Researchers have found that increased sensitivity to certain cytokines leads to greater activation of T cells in the blood of patients with multiple sclerosis. These T cells are more likely to migrate into the central nervous system of patients and cause the damage that causes multiple sclerosis there.
Better understand the causes of MS to treat it better tomorrow
“IThe results of this study are particularly valuable compared to previous MS studies that did not take genetic predisposition into account.”, says Burkhard Becher, another author of the study. “We are thus able to discover which part of the immune dysfunction in MS is influenced by genetic components and which part is influenced by environmental factors. This is of fundamental importance for understanding the development of the disease. he concludes.