2023-05-27 15:00:00
This is a major breakthrough for people with multiple sclerosis: Dutch researchers have discovered that patients with multiple sclerosis (MS) have structural abnormalities in their white matter (or myelin) even before the inflammation of multiple sclerosis does not develop.
The results of their work have been published in Annals of Neurology.
Multiple sclerosis affects the nervous system
Multiple sclerosis (MS) is a chronic inflammatory autoimmune disease of the central nervous system, explains theInserm : “A dysfunction of the immune system leads to lesions that cause motor, sensory, cognitive, visual or even sphincter disturbances (most often urinary and intestinal)”. In early or advanced progressive multiple sclerosis, lesions appear in the brain along with significant inflammatory activity.
Through their study of post-mortem human brains from MS patients and controls that were donated to the Dutch Brain Bank, the researchers saw a change in their myelin.
This white, insulating fatty substance in the brain wraps up to 150 times around nerve fibers. It is like an insulating sheath that surrounds the extensions of neurons, is essential for the proper conduction of nerve impulses and the proper functioning of neurons, according to the‘Brain Institute.
Multiple sclerosis: a defect in the brain causes the symptoms
Indeed, at regular distances from each other, the myelin is interrupted by nodes of Ranvier. “When transmitting electrical signals, the signal jumps from one node of Ranvier to another, allowing a fiber containing myelin to transmit a signal 100 times faster than without myelin. In people with MS, myelin is damaged and signal transmission in the central nervous system is disrupted, which can impair functions such as walking and vision”, write the authors of the study.
The researchers found that the myelin of MS patients was less tightly wrapped around the nerve fiber. Thus the fiber is not properly isolated, which has important consequences: the signal cannot be transmitted as quickly as before and the symptoms appear.
Multiple sclerosis: towards a white matter treatment?
Also, along with the damaged myelin, more mitochondria – the small structures inside cells – grow, the researchers noted.
But that makes the situation even worse. Indeed, although mitochondria are generally useful for cell energy production, they also produce many by-products, such as oxygen radicals that amplify the breakdown of myelin, explain the authors.
Armed with these discoveries, researchers now want to find out how to prevent these deleterious phenomena for brain health from occurring:
“The next step will be to see if we can prevent myelin from wrapping so loosely around nerve endings (…) It would be great to find a way to prevent myelin from detaching. Although this does not prevent lesions that are already present, it might prevent new lesions from developing. This would be an entirely new target for the treatment of multiple sclerosis”, said Aletta van den Bosch of the research team at the Netherlands Institute for Neuroscience.
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