Multiple sclerosis: a treatment to curb the disease and protect the immune system

Multiple sclerosis is an autoimmune disease in which the immune system turns against the body. For the moment, the treatments aim to lower the reactions of the immune system, which is risky in view of the serious side effects that this implies, in particular with the occurrence of infections or even cancers. Researchers at Jefferson University (United States) have found a way to prevent the immune system from attacking the body, and therefore to stop the progression of multiple sclerosis. The results of their study were published on November 4, 2020 in the journal Science Translational Medicine.

When multiple sclerosis develops in humans, it attacks the electrical insulation around the axon of neurons, the myelin sheath. This sheath allows the electrical impulse passing from one neuron to another not to be lost, which affects the speed of the exchange of information. All the interest of current research is to find a way to preserve these sheaths and stop the attack produced by the immune system.

Antigens present in extracellular vesicles

“There are many possible immuno-activating antigens in the myelin sheath, but the biggest hurdle is that we don’t know which component of myelin triggers the immune response in patients with multiple sclerosis.says Abdolmohamad Rostami, director of the department of neurology at Jefferson University. Previous studies have used single myelin antigens or combinations of antigens to prevent autoimmunity in animal models, but in humans have had limited success..”

To better understand, the researchers went to analyze oligodendrocytes, the cells responsible for making the myelin sheath in the central nervous system. When grown in vitro, oligodendrocytes produce extracellular vesicles, which contain all myelin antigens. Thus, it appears easier to stop an autoimmune attack thanks to the antigens present in these vesicles. “The value of these extracellular vesicles is that they give us the ability to treat disease in an antigen-specific way, without having to know the exact identity of the target antigen.”, emphasizes Abdolmohamad Rostami.

A slowed disease and a preserved immune system

These extracellular vesicles were injected into three mice affected by multiple sclerosis at the early or advanced stages of the disease. When administered before the development of the disease, the extracellular vesicles have a prophylactic effect, which prevents the mice from suffering from paralysis or reduced mobility. If extracellular vesicles are injected after multiple sclerosis has set in, the severity of the disease is significantly reduced. In addition, this method does not attack the myelin sheath and leaves the immune system intact, which is not weakened.

“The antigens involved in the autoimmune response may differ between MS patients, and even change over time in an individual patient. The fact that our approach has been effective in different experimental models shows that it could act as a universal therapy.”, explains Abdolmohamad Rostami. He pursues: “This is a huge advantage of our antigen-specific method over current therapies, which destroy the immune system. That’s what makes ours so innovative.”

The same extracellular vesicles have been isolated in humans. As with mice, they also have multiple myelin antigens within them, which could therefore provide the same therapeutic effect as the rodents tested. Abdolmohamad Rostami and his team are now seeking to patent their approach, which could be a breakthrough for the treatment of multiple sclerosis.