Narcolepsy: If You Sleep Too Much, It Could Be Your Immune System’s Fault

Narcoleptics have difficulty standing up for more than one to two hours in a row without falling asleep. This excessive daytime sleepinessis accompanied by cataplexies, that is to say a loss of muscle tone triggered by an emotion that is often pleasant, such as giggles. Narcolepsy-cataplexy is thought to be caused by the loss or dysfunction of specific neurons located in the lateral hypothalamus and which normally secrete a neurotransmitter, orexin, which stimulates appetite and arousal.

Researchers agree that the origin of this disease is autoimmune, and is linked to a failure of the immune system. To confirm this hypothesis, researchers from Inserm (Unit 1043 “Center for Physiopathology of Toulouse-Purpan” have developed a mouse model simulating narcolepsy.

They generated mice expressing an autoantigen in orexinergic neurons. An autoantigen is the normal component of the body which is attacked by the immune system in the event of an autoimmune disease.

Immunotherapy, a way to treat narcolepsy

T cells (lymphocytes who will carry out the immune message) responsible for stimulating this autoantigen were then injected into rodents to see how the orexinergic neurons reacted.

Verdict, the administered lymphocytes triggered local inflammation without destroying the affected neurons. If these had been destroyed, the mice would have developed cataplexy and sleep disturbances, similar to human narcolepsy.

“These results suggest that immunotherapy could be used in the treatment of narcolepsy-cataplexy and identifies a potential cellular target for this therapeutic strategy” concludes in a Inserm press release Roland Liblau, Inserm researcher who carried out this work.

Narcolepsy is an extremely rare but serious disorder that affects on average 2 people per 10,000.

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