Research team identifies the triggers of rare sleeping sickness
In the rare sleeping sickness narcolepsy, sufferers suffer from pronounced daytime sleepiness and tend to fall asleep suddenly. The chronic illness was documented as early as 1877, but the causes of the illness have remained a mystery to this day. A Swiss study has now brought light into the dark. Researchers were able to decipher the causes of narcolepsy.
Sudden sleep attacks, disturbed night sleep, hallucinations, loss of muscle control - narcolepsy is a hard cut in the quality of life for those affected. Sudden falling asleep is also associated with the risk of accidents. Until now, patients with chronic sleeping sickness did not know why they suffer from this illness. A Swiss research team with the participation of the University Sleep-Wake Epilepsy Center Bern (SWEZ) has now found the causes of rare narcolepsy. Her study results were recently published in the renowned journal "Nature".
Narcolepsy - a rare and enigmatic condition
Only around 0.05 percent of the population suffers from chronic sleeping sickness, the researchers report. The underlying mechanisms have largely remained a mystery since the discovery of the disease. The team led by Professor Federica Sallusto at the Institute for Research in Biomedicine in Bellinzona (IRB) and Professor Claudio LA Bassetti from the University Sleep-Wake Epilepsy Center (SWEZ) at the University Clinic for Neurology at the Inselspital in Bern made the breakthrough, identified the triggers and now offers new possibilities for diagnosis and therapy.
What was already known
From previous research, it was already known that narcolepsy is caused by the constant loss of a protein in the brain. The decrease in the protein hypocretin is genetic, according to the Swiss research group, and usually occurs in certain people who have a genetic susceptibility to it. Until now, why the protein has been lost has not been sufficiently understood.
Immune reactions trigger the sleeping sickness
In their study, the Swiss researchers showed for the first time that immune reactions are responsible for the loss of the protein hypocretin. The team identified so-called autoreactive T lymphocytes that elicit an immune response that causes the loss. Lymphocytes are white blood cells and are natural components of the blood. Its tasks include the detection and destruction of foreign substances such as viruses and bacteria. In narcolepsy patients, the autoreactive T-lymphocytes destroy certain neurons in the brain that are responsible for the production of hypocretin.
New therapy option
"With new sensitive methods, we were able to identify autoreactive T cells as the cause of this disease," Professor Federica Sallusto sums up the study results in a press release from the University Hospital of Bern. These lymphocytes could cause inflammation that could result in neuronal damage or even destroy hypocretin-producing neurons. "If we block autoreactive T cells in the early stages, we may be able to limit neuronal loss and prevent the disease from progressing," Sallusto explains.
Narcolepsy is often recognized too late
"This study will raise awareness of narcolepsy, which is little known in the general population and is often underdiagnosed by doctors or too late," adds Professor Claudio Bassetti. The new findings would open up new opportunities for early diagnosis as well as new treatment approaches.
What does the protein hypocretin do?
As already mentioned, the loss of hypocretin leads to the typical symptoms of sleeping sickness such as chronic fatigue, sleep disorders, sleep attacks, impaired consciousness and loss of muscle control. The protein hypocretin is produced in the hypothalamic region of the brain and regulates sleep-wake behavior as well as emotional and nutritional behavior. A certain genetic marker is present in 95 percent of narcolepsy patients (HLA allele DQB1 * 0602). For this reason, doctors assume that it is an autoimmune disease.
Narcolepsy often occurs after infectious diseases
As the researchers report, narcolepsy often occurs as a result of infectious diseases such as after a flu (influenza). This points to a possible role of environmental factors as triggers of the autoimmune process. However, the exact mechanisms why the T lymphocytes attack the neurons in the brain remain unclear. (vb)