Plasma levels of tumor necrosis factor alpha and soluble tumor necrosis factor receptors in patients with narcolepsy.
BACKGROUND
Narcolepsy is a disabling sleep disorder characterized by excessive daytime sleepiness, cataplexy, hypnagogic hallucinations, and sleep paralysis. Recent studies suggest that the immune system might play a pathogenic role pointing to a possible involvement of inflammatory cytokines.


METHODS
We investigated a sample of 30 patients with narcolepsy in comparison with 120 sex- and age-matched and 101 sex-, body mass index (BMI)-, and age-matched randomly selected normal controls. In these groups, plasma concentrations of tumor necrosis factor alpha (TNF-alpha) and its soluble receptors p55 and p75 (soluble TNF receptor [sTNF-R] p55 and sTNF-R p75) were measured using commercial enzyme-linked immunosorbent assays.


RESULTS
The narcoleptic patients showed a significantly higher BMI compared with controls of the same age. Soluble TNF-R p75 levels were consistently elevated in the narcoleptic patients compared with their sex- and age-matched (P = .001) as well as sex-, BMI-, and age-matched counterparts (P = .003). Female narcoleptic patients exhibited higher sTNF-R p55 levels compared with their sex- and age-matched controls (P = .01), but this difference disappeared when comparing patients with sex-, BMI-, and age-matched normal controls. Tumor necrosis factor alpha levels did not differ significantly between groups.


CONCLUSIONS
Narcoleptic patients show increased plasma levels of sTNF-R p75, suggesting a functional alteration of the TNF-alpha cytokine system, further corroborating a possible pathogenic role of the immune system in this sleep disorder.
Himmerich
Hubertus
H
Max Planck Institute of Psychiatry, Munich, Germany. himmerich@mpipsykl.mpg.de
Beitinger
Pierre A
PA
Fulda
Stephany
S
Wehrle
Renate
R
Linseisen
Jakob
J
Wolfram
Günther
G
Himmerich
Stephanie
S
Gedrich
Kurt
K
Wetter
Thomas C
TC
Pollmächer
Thomas
T
D015992:Body Mass Index; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009290:Narcolepsy / Q000097:blood / Q000276:immunology*; D018124:Receptors, Tumor Necrosis Factor / Q000097:blood*; D012737:Sex Factors; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*
D018124:Receptors, Tumor Necrosis Factor; D014409:Tumor Necrosis Factor-alpha