Reduced glucocorticoid sensitivity of monocyte interleukin-6 release in male employees with high plasma levels of tumor necrosis factor-alpha.
Cytokine production by monocytes plays a key role in atherosclerosis. In vitro, preincubation of whole blood with tumor necrosis factor (TNF)-alpha regulates interleukin (IL)-6 release from monocytes stimulated with lipopolysaccharide (LPS). We investigated whether plasma levels of TNF-alpha would also relate to LPS-stimulated monocyte IL-6 production and the inhibitory effect of a glucocorticoid on this process. 224 middle-aged men were assigned to three groups according to tertiles of plasma levels of TNF-alpha. Subjects in the highest tertile (high TNF-alpha, n = 75) were compared to those in the lowest (low TNF-alpha, n = 74) and medium tertile (medium TNF-alpha, n = 75), respectively. In vitro monocyte IL-6 release following lipopolysaccharide (LPS)-stimulation was assessed with and without coincubation with incremental doses of dexamethasone. Monocyte glucocorticoid sensitivity was defined as the dexamethasone concentration inhibiting IL-6 release by 50%. Subjects with high TNF-alpha showed more IL-6 release after LPS-stimulation than those with low TNF-alpha (p =.011). Monocyte glucocorticoid sensitivity was lower in subjects with high levels of TNF-alpha than in subjects with low (p =.014) and with medium (p =.044) levels of TNF-alpha. Results held significance when a set of classic cardiovascular risk factors was controlled for. Our findings suggest that elevated plasma levels of TNF-alpha might enhance LPS-stimulated IL-6 release from circulating monocytes. Such a mechanism might contribute to exaggerated monocyte cytokine release in vivo to any LPS-like danger signal such as related to an infection or cellular stress thereby promoting atherosclerosis.
Wirtz
Petra H
PH
Department of Clinical Psychology and Psychotherapy, University of Zurich, Zürichbergstrasse 43, 8044 Zurich, Switzerland.
von Känel
Roland
R
Kunz-Ebrecht
Sabine
S
Ehlert
Ulrike
U
Fischer
Joachim E
JE
D000328:Adult; D001161:Arteriosclerosis / Q000209:etiology; D003907:Dexamethasone / Q000494:pharmacology*; D005938:Glucocorticoids / Q000494:pharmacology*; D006801:Humans; D066298:In Vitro Techniques; D008070:Lipopolysaccharides; D008297:Male; D009000:Monocytes / Q000187:drug effects / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*
D005938:Glucocorticoids; D008070:Lipopolysaccharides; D014409:Tumor Necrosis Factor-alpha; D003907:Dexamethasone