Certain environmental conditions may lead to structural changes in the protective sheaths that cover nerve fibers and thus trigger multiple sclerosis, a team of Tel Aviv University researchers has found.
The research shows that myelin sheaths — the “insulating tape” surrounding axons, which carry electrical impulses in neurons — undergo structural changes when triggered by certain conditions, such as salt concentration (salinity) and temperature. These changes in the myelin sheaths, according to the study, make the body vulnerable to autoimmune attacks that can lead to MS.
The disease causes the immune system to attack the myelin that covers nerve fibers, and thus causes communication problems between the brain and the rest of the body. Some 1 million people in the US are estimated to be affected by the disease, according to preliminary results of a study by the National MS Society.
The research was led by Prof. Roy Beck of TAU’s School of Physics and Astronomy and conducted by Rona Shaharabani, a doctoral student in Beck’s lab, and Maor Ram-On, a doctoral student in Prof. Ronen Talmon’s lab at the Technion Institute of Technology. It was published in the Proceedings of the National Academy of Sciences of the USA (PNAS).
Earlier research by Beck revealed that changes in the structure of myelin sheaths are a factor in the development of MS.
“Current therapeutic approaches have focused on the autoimmune response without identifying the culprit,” he said. “We have found that under certain environmental conditions, such as elevated salinity and temperature, myelin sheaths protecting neurons undergo structural transitions consistent with pathological myelin structures in multiple sclerosis.”
Physiological conditions are regulated in the body itself, but the body’s temperature and salinity are subject to localized external changes. The results presented in the study suggest that even minor changes in these conditions may trigger multiple sclerosis.
“The myelin sheaths undergo structural transitions at the molecular level when affected by different environmental conditions. These small modifications create structural instabilities that allow the immune system to attack neurons,” said Shaharabani.
The study is very initial, said Beck in a phone interview, and the findings do not mean that people should stop ingesting salt or taking hot baths. What it does mean, he said, is that “further research is needed to understand how environmental conditions impact and are regulated in diseased patients.”
The researchers used X-ray scattering and cryogenic transmission electron microscopy (cryo-TEM) to track and measure the myelin sheaths in healthy and diseased animal models, after exposing them to the different environmental conditions. The found that “drastic structural reorganization and instabilities of myelin membrane are linked to specific environmental conditions,” and healthy lamellar membranes — membrane -coating granules — spontaneously changed into different pathological structures.
“These results highlight that local environmental conditions are critical for myelin function,” said Shaharabani. These conditions should be taken into account as alternative ways to help with the early diagnosis of the disease or as a way of avoiding the “onset of demyelination,” she said.
“Since we believe that these structural modifications result in myelin membrane vulnerability to the immune system attacks, it can help explain the causes of MS and perhaps pave the way for a treatment or a cure,” Shararabani said.
Shaharabani said that the researchers are now looking for other factors that could cause structural changes to myelin function, “which may unravel further insights to fight multiple sclerosis and related disorders.”