New proof that narcolepsy is an autoimmune disease

Researchers at the University of Copenhagen have discovered self-reactive cells in people with narcolepsy. This is a new important proof that the sleep disorder is an autoimmune disease. This knowledge could lead to better treatment of chronic disease, say researchers at the origin of this new discovery.

Scientists have been waiting for many years for the narcolepsy of sleep disorders to be an autoimmune disease, but can not conclusively prove it. Researchers from the Faculty of Health Sciences and Medical Sciences of the University of Copenhagen as well as the Technical University of Denmark and Rigshospitalet have discovered new important evidence attesting to the accuracy of their hypotheses. The new research results have been published in the scientific journal Nature Communications.

"We found self-reactive cytotoxic CD8 T cells in the blood of patients with narcolepsy. That is, the cells recognize the neurons that produce the hypocretin that regulates the waking state of a person. This does not prove that they are the ones who killed the neurons, but it is an important step forward. We now know what the cells are for, "says Associate Professor Birgitte Rahbek Kornum from the Department of Neuroscience.

The immune system is designed to recognize viruses and bacteria. When its cells are self-reactive, as is the case in autoimmune diseases, the immune system recognizes the body's own cells and attacks them. The fact that they are cytotoxic means that they are able to kill other cells. In most patients with narcolepsy, neurons that produce hypocretin and thus regulate our waking state have been destroyed.

& # 39; To kill other cells, for example hypocretin producing neurons, CD4 and CD8 usually have to work together. In 2018, scientists discovered self-reactive CD4 T cells in patients with narcolepsy. It was really the first evidence that narcolepsy was actually an autoimmune disease. We have now provided additional and important evidence: CD8 T cells are also self-reactive, "says Professor Rahbek Kornum.

Self-reactive cells have also been found in healthy individuals

In the study, researchers studied and analyzed blood samples from 20 people with narcolepsy. In addition, they analyzed blood samples from a control group of 52 healthy people. In almost all 20 patients with narcolepsy, the researchers found autoreactive CD8 T cells. However, self-reactivity was not found only in people with sleep disorders. Researchers have also discovered self-reactive cells in many healthy individuals.

"We also found self-reactive cells in some of the healthy individuals, but here the cells probably have not been activated. This is something we see more and more often with autoimmunity, that is, it is dormant in all of us, but not activated in everyone. The next big puzzle is learning what activates them, "says Rahbek Kornum.

According to Rahbek Kornum, the discovery of self-reactive cells in healthy individuals also underscores the theory that something must trigger narcolepsy and activate self-reactivity. Scientists still do not know what causes the disease. They expect that a combination of genetics, self-reactive cells and a trigger form will cause the disease, e.g. a viral infection. The disease can be treated medically today, but new research findings could pave the way for even better treatments.

"We will probably focus more on treating narcolepsy with drugs that affect the immune system. This has however already been attempted because the hypothesis that there is an autoimmune disease has existed for many years. But now that we know that T cells are induced, we can begin to target and make immune treatments even more effective and accurate, "said Rahbek Kornum.

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University of Copenhagen