Cold to fight multiple sclerosis

Change focus. That is what a group of scientists from the
University of Geneva-UNIGE (Switzerland)
to treat multiple sclerosis. It is about diverting the immune system, whose malfunction causes this autoimmune disease, with something else. And they propose cold.

In evolutionary biology, the “theory of the history of life”, first proposed in the 1950s, posits that when the environment is favorable, the resources used by any organism are dedicated to growth and reproduction. On the contrary, in a hostile environment, resources are transferred to so-called maintenance programs, such as energy conservation and defense against external attacks.

now researchers from the
UNIGE
is to apply this concept in a specific field of medicine: the erroneous activation of the immune system that causes autoimmune diseases.

By studying mice with a model of multiple sclerosis, the scientists discovered how exposure to low temperatures forced the body to divert its resources of the immune system towards the maintenance of body heat.

In fact, during the cold, the immune system lowered its harmful activity, which considerably attenuated the course of the autoimmune disease.

These results, which deserve the cover of the journal “Cell Metabolism”, open the way to a fundamental biological concept on the allocation of energetic resources.

Autoimmune diseases occur when the immune system attacks the body’s own organs. For example, the Diabetes type 1, for example, it is caused by the mistaken destruction of insulin-producing cells of the pancreas.

Multiple sclerosis is the most common autoimmune disease of the central nervous system (consisting of the brain and spinal cord). The ailment is characterized by the destruction of myelin, which is a protector of nerve cells and is important for the correct and rapid transmission of electrical signals. Therefore, its loss leads to a neurological disability, including paralysis.

After a few days, we observed a clear improvement in the severity of the disease, as well as in the degree of demyelination observed in the central nervous system

“The defense mechanisms of our body against the hostile environment are energetically expensive and can be limited by compensations when several of them are activated. Therefore, the body may have to prioritize the allocation of resources to different defense programs based on their survival values, “he explains. Mirko Trajkovski, lead author of the study.

His team thought this may be of particular concern for autoimmunity, where the introduction of an additional energy-costly program can elicit a milder immune response and thereby affect disease. In other words, “Could we divert the energy that the body expends when the immune system fails?».

To test their hypothesis, the scientists subjected mice that suffered from experimental autoimmune encephalomyelitis, a model of human multiple sclerosis, to a relatively cooler environment, around 10 ° C after an acclimatization period of gradual decrease in ambient temperature.

«After a few days, we observed a clear improvement in the severity of the disease, as well as in the degree of demyelination observed in the central nervous system ”, details Doron Merkler, co-author of the work.

In autoimmune diseases, however, self antigens are confused with foreign ones.

In addition, he highlights, “the animals had no difficulty in maintaining their body temperature at a normal level, but, curiously, the symptoms of the alterations of the locomotor system decreased drastically, from not being able to walk on their hind legs to only a slight paralysis of the The tail”.

The researchers explain that the immune response is based, among other things, on the ability of so-called antigen-presenting monocytes to instruct T cells on how to recognize foreign elements that need to be fought off.

In autoimmune diseases, however, self antigens are mistaken for foreign ones.

In this study, he points out Mirko Trajkovski, «We show that the cold modulates the activity of inflammatory monocytes by decreasing their ability to present antigens, which makes T cells, a type of cell with a critical role in autoimmunity, less activated.

That is, by forcing the body to increase its metabolism to maintain body heat, cold robs the immune system of resources. This causes a decrease in harmful immune cells and thus improves the symptoms of the disease.

“While the concept of prioritizing thermogenic response over immune response is clearly protective against autoimmunity, it is worth noting that exposure to cold increases susceptibility to certain infections. Therefore, our work could be relevant not only for neuroinflammation, but also for other infectious or immune-mediated diseases, which deserves further investigation, ”adds Trajkovski.

Our work could be relevant not only for neuroinflammation, but also for other infectious or immune-mediated diseases, which deserves further investigation.

The truth is that an increase in autoimmune diseases has been observed for some time. The improvement in living conditions in Western countries, which has been noted in recent decades, has gone hand in hand with an increase in cases of autoimmune diseases. “Although this increase is undoubtedly multifactorial, the fact that we have an abundance of energy resources at our disposal can play an important role, but still little known, in the development of autoimmune diseases “, concludes Doro Merkler.

The researchers will now continue their research to answer the million dollar question: Can their discoveries be applied to develop a clinical application for humans?

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