TY - JOUR
TI - Circadian rhythmicity, variability and correlation of interleukin-6
levels in plasma and cerebrospinal fluid of healthy men
AU - Agorastos, Agorastos
AU - Hauger, Richard L.
AU - Barkauskas, Donald A.
AU - and Moeller-Bertram, Tobias
AU - Clopton, Paul L.
AU - Haji, Uzair and
AU - Lohr, James B.
AU - Geracioti, Jr., Thomas D.
AU - Patel, Piyush M. and
AU - Chrousos, George P.
AU - Baker, Dewleen G.
JO - Psychoneuroendocrinology
PY - 2014
VL - 44
TODO - null
SP - 71-82
PB - PERGAMON-ELSEVIER SCIENCE LTD
SN - 0306-4530
TODO - 10.1016/j.psyneuen.2014.02.020
TODO - Interleukin-6 (IL-6); Cytokines; Circadian; Immune; Inflammation; Blood
brain-barrier (BBB); Cerebrospinal fluid (CSF); Sleep; Stress;
Neuroimmunology
TODO - Background: Interleukin-6 (IL-6) is a cytokine with pleiotropic actions
in both the periphery of the body and the central nervous system (CNS).
Altered IL-6 secretion has been associated with inflammatory
dysregulation and several adverse health consequences. However, little
is known about the physiological circadian characteristics and dynamic
inter-correlation between circulating and CNS IL-6 levels in humans, or
their significance.
Methods: Simultaneous assessment of plasma and cerebrospinal fluid (CSF)
IL-6 levels was performed hourly in 11 healthy male volunteers over 24
h, to characterize physiological IL-6 secretion levels in both
compartments.
Results: IL-6 levels showed considerable within- and between-subject
variability in both plasma and CSF, with plasma/CSF ratios revealing
consistently higher levels in the CSF. Both CSF and plasma IL-6 levels
showed a distinctive circadian variation, with CSF IL-6 levels
exhibiting a main 24 h, and plasma a biphasic 12 h, circadian component.
Plasma peaks were roughly at 4 p.m. and 4 a.m., while the CSF peak was
at around 7 p.m. There was no correlation between coincident CSF and
plasma IL-6 values, but evidence for significant correlations at a
negative 7-8 h time lag.
Conclusions: This study provides evidence in humans for a circadian IL-6
rhythm in CSF and confirms prior observations reporting a plasma
biphasic circadian pattern. Our results indicate differential IL-6
regulation across the two compartments and are consistent with local
production of IL-6 in the CNS. Possible physiological significance is
discussed and implications for further research are highlighted.
Published by Elsevier
ER -