Diurnal rhythms of pro-inflammatory cytokines: regulation by plasma cortisol and therapeutic implications.

Abstract

Clinical features of certain immuno-inflammatory disorders such as rheumatoid arthritis and asthma exhibit diurnal fluctuation, which could be related to diurnal rhythmicity of pro-inflammatory cytokine production. To investigate the latter, the authors performed measurements of lipopolysaccharide (LPS)-stimulated whole blood, interferon gamma (IFN-gamma), tumour necrosis factor alpha (TNF-alpha), interleukin 1 (IL-1) and IL-12 production in 13 healthy volunteers over 24 h. These cytokines exhibited distinct diurnal rhythms that peaked in the early morning and were inversely related to the rhythm of plasma cortisol. Elevation of plasma cortisol within the physiological range by administratio..