title: Circadian rhythm of the soluble p75 tumor necrosis factor (sTNF-R75) receptor in humans--a possible explanation for the circadian kinetics of TNR-alpha effects.
abstract: Circadian alterations of several immune functions in vivo are well established, and may have important physiological and clinical implications. In line with this, tumor necrosis factor (TNF)-alpha has been implicated in the circadian regulation of body temperature. As soluble TNF receptors (TNF-R) act as naturally occurring competitive inhibitors of this cytokine, we investigated plasma levels of the soluble sTNF-R55 and sTNF-R75 in comparison with plasma cortisol and body temperature in nine healthy male volunteers during a defined 16 h light/8 h dark cycle. It was found that sTNF-R75, but not sTNF-R55, exhibited a clear-cut circadian rhythm with a significant (P < 0.01) peak at 7:51 a.m. +/- 58 min. The phase of the sTNF-R75 rhythm preceded that of cortisol by approximately 1 h and inversely corresponded to the circadian rhythm of body temperature. Moreover, the individual amplitudes of sTNF-R75 and body temperature exhibited a significant (P < 0.01) positive correlation. These results suggest that (i) the two sTNF-R are regulated independently, (ii) the sTNF-R75 rhythm is not primarily due to the cortisol rhythm and (iii) the fluctuation of the sTNF-R may contribute to the regulation of body temperature by modulating the availability of free TNF.
authors.affiliation: Department of General and Experimental Pathology, University of Graz, Austria.
authors.forename: P M
authors.initials: PM
authors.lastname: Liebmann
authors.forename: G
authors.initials: G
authors.lastname: Reibnegger
authors.forename: M
authors.initials: M
authors.lastname: Lehofer
authors.forename: M
authors.initials: M
authors.lastname: Moser
authors.forename: P
authors.initials: P
authors.lastname: Pürstner
authors.forename: H
authors.initials: H
authors.lastname: Mangge
authors.forename: K
authors.initials: K
authors.lastname: Schauenstein
mesh_terms: D000328:Adult; D015703:Antigens, CD / Q000097:blood*; D001831:Body Temperature / Q000502:physiology; D002940:Circadian Rhythm; D006801:Humans; D006854:Hydrocortisone / Q000097:blood; D007700:Kinetics; D008297:Male; D018124:Receptors, Tumor Necrosis Factor / Q000097:blood*; D047888:Receptors, Tumor Necrosis Factor, Type I; D047889:Receptors, Tumor Necrosis Factor, Type II; D014409:Tumor Necrosis Factor-alpha / Q000502:physiology*
chemical_list: D015703:Antigens, CD; D018124:Receptors, Tumor Necrosis Factor; D047888:Receptors, Tumor Necrosis Factor, Type I; D047889:Receptors, Tumor Necrosis Factor, Type II; D014409:Tumor Necrosis Factor-alpha; D006854:Hydrocortisone