Sex differences in monocyte expression of IL-6: role of autonomic mechanisms.

TitleSex differences in monocyte expression of IL-6: role of autonomic mechanisms.
Publication TypeJournal Article
Year of Publication2007
AuthorsO'Connor M-F, Motivala SJ, Valladares EM, Olmstead R, Irwin MR
JournalAm J Physiol Regul Integr Comp Physiol
Date Published2007 Jul
KeywordsAdult, Autonomic Nervous System, Circadian Rhythm, Female, Heart Rate, Hormones, Humans, Interleukin-6, Lipopolysaccharides, Male, Middle Aged, Monocytes, Parasympathetic Nervous System, Sex Characteristics, Sympathetic Nervous System, Toll-Like Receptor 4, Vagus Nerve

Sex differences in the prevalence of inflammatory disorders exist, perhaps due to sex differences in cellular mechanisms that contribute to proinflammatory cytokine activity. This study analyzed sex differences of monocyte intracellular expression of IL-6 and its associations with reproductive hormones and autonomic mechanisms in 14 matched pairs of men and women (n = 28). Monocyte intracellular IL-6 production was repeatedly assessed over two circadian periods. Sympathetic balance was estimated by heart rate variability and the ratio of power in the low-frequency (LF) to high-frequency (HF); vagal tone was indexed by the power of HF component. As compared to men, women showed greater monocyte expression of IL-6 across the circadian period. In addition, women showed lower sympathetic balance (LF/HF ratio), and greater levels of vagal tone (HF power). In women, but not men, sympathovagal balance was negatively associated with monocyte IL-6 expression, whereas vagal tone was positively associated with production of this cytokine. Levels of reproductive hormones were not related to monocyte IL-6 expression. The marked increase in monocyte expression of interleukin-6 in women has implications for understanding sex differences in risk of inflammatory disorders. Additionally, these data suggest that sex differences in sympathovagal balance or vagal tone may be a pathway to explain sex differences in IL-6 expression. Interventions that target autonomic mechanisms might constitute new strategies to constrain IL-6 production with impacts on inflammatory disease risk in women.

Alternate JournalAm. J. Physiol. Regul. Integr. Comp. Physiol.
PubMed ID17428894
Grant ListAA 13239 / AA / NIAAA NIH HHS / United States
AG 18367 / AG / NIA NIH HHS / United States
AI 52737 / AI / NIAID NIH HHS / United States
DA 16541 / DA / NIDA NIH HHS / United States
HL 079955 / HL / NHLBI NIH HHS / United States
K01 AG028404 / AG / NIA NIH HHS / United States
M01 RR 00827 / RR / NCRR NIH HHS / United States
M01 RR 00865 / RR / NCRR NIH HHS / United States
MH 55253 / MH / NIMH NIH HHS / United States
T32 MH 19925 / MH / NIMH NIH HHS / United States