Narcolepsy as an autoimmune disease: the role of H1N1 infection and vaccination.
Narcolepsy is a sleep disorder characterised by loss of hypothalamic hypocretin (orexin) neurons. The prevalence of narcolepsy is about 30 per 100 000 people, and typical age at onset is 12-16 years. Narcolepsy is strongly associated with the HLA-DQB1*06:02 genotype, and has been thought of as an immune-mediated disease. Other risk genes, such as T-cell-receptor α chain and purinergic receptor subtype 2Y11, are also implicated. Interest in narcolepsy has increased since the epidemiological observations that H1N1 infection and vaccination are potential triggering factors, and an increase in the incidence of narcolepsy after the pandemic AS03 adjuvanted H1N1 vaccination in 2010 from Sweden and Finland supports the immune-mediated pathogenesis. Epidemiological observations from studies in China also suggest a role for H1N1 virus infections as a trigger for narcolepsy. Although the pathological mechanisms are unknown, an H1N1 virus-derived antigen might be the trigger.
Helsinki Sleep Clinic, Vitalmed Research Centre, Helsinki, Finland; Department of Clinical Neurosciences, University of Helsinki, Helsinki, Finland. Electronic address: markku.partinen@helsinki.fi.
Markku
M
Partinen
Molecular Sleep Laboratory, Department of Diagnostics, Glostrup Hospital, Glostrup, Denmark.
Birgitte Rahbek
BR
Kornum
Department of Biomedical and Neuromotor Sciences, University of Bologna, Italy; IRCCS Istituto delle Scienze Neurologiche, Bologna, Italy.
Giuseppe
G
Plazzi
Danish Center for Sleep Medicine, Department of Clinical Neurophysiology, University of Copenhagen, Glostrup Hospital, Glostrup, Denmark.
Poul
P
Jennum
Department of Virology, University of Turku, Turku, Finland; Department of Infectious Disease Surveillance and Control, National Institute for Health and Welfare, Helsinki, Finland.
Ilkka
I
Julkunen
Department of Vaccines and Immune Protection, National Institute for Health and Welfare, Helsinki, Finland.
Outi
O
Vaarala
D020274:Autoimmune Diseases of the Nervous System / Q000453:epidemiology / Q000276:immunology* / Q000821:virology*; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype / Q000276:immunology* / Q000472:pathogenicity; D007251:Influenza, Human / Q000150:complications / Q000453:epidemiology / Q000276:immunology*; D009290:Narcolepsy / Q000453:epidemiology / Q000276:immunology* / Q000821:virology; D014611:Vaccination / Q000009:adverse effects*