Tumor necrosis factor alpha decreases, and interleukin-10 increases, the sensitivity of human monocytes to dexamethasone: potential regulation of the glucocorticoid receptor.
Resistance to glucocorticoid therapy has been observed in patients with autoimmune/inflammatory diseases and may be related to the inflammatory process itself. The aim of this study was to examine the ability of tumor necrosis factor alpha (TNFalpha, a proinflammatory cytokine) and interleukin (IL)-10 (an anti-inflammatory cytokine) to differentially regulate the sensitivity of human monocytes/macrophages to glucocorticoids. To accomplish this, we first analyzed the pattern of TNFalpha and IL-10 inhibition by dexamethasone in LPS-stimulated whole-blood cell cultures. Second, we studied the modulation of the sensitivity of these cells to dexamethasone by preincubation with TNFalpha or IL-10 and measurement of LPS-stimulated IL-6 secretion. In addition, we evaluated the effect of dexamethasone on phorbolmyristate-acetate-stimulated IL-1 receptor antagonist secretion by the human monocytic cell line U937. Finally, we investigated whether the modulation of corticosensitivity in TNFalpha- and IL-10-pretreated U937 cells was related to a change of the glucocorticoid receptor concentration and affinity. Dexamethasone had different effects on LPS-induced TNFalpha and IL-10 secretion; whereas it suppressed TNFalpha in a dose-dependent fashion, its effect on IL-10 secretion was biphasic, producing stimulation at lower, and inhibition at higher doses. The concentration of LPS employed influenced the effect of dexamethasone on IL-10 secretion (P < 0.001). Pretreatment with TNFalpha diminished, and with IL-10 improved, the ability of dexamethasone to suppress IL-6 secretion in whole-blood cell cultures (P < 0.01 for both) and to enhance IL-1 receptor antagonist secretion by U937 cells (P < 0.05 for both). TNFalpha decreased (P < 0.001), while IL-10 increased (P < 0.001), the concentration of dexamethasone binding sites in these cells, with no discernible effect on their binding affinity. We conclude that glucocorticoids differentially modulate TNFalpha and IL-10 secretion by human monocytes in a LPS dose-dependent fashion and that the sensitivity of these cells to glucocorticoids is altered by TNFalpha or IL-10 pretreatment; TNFalpha blocks their effects, whereas IL-10 acts synergistically with glucocorticoids. This is accompanied by opposite glucocorticoid receptor changes, respectively opposing and favoring glucocorticoid actions. This study suggests that the pattern of pro-/antiinflammatory cytokine secretion may alter the response of patients to glucocorticoid therapy.
Franchimont
D
D
Department of Gastroenterology CHU, University of Liège, Belgium.
Martens
H
H
Hagelstein
M T
MT
Louis
E
E
Dewe
W
W
Chrousos
G P
GP
Belaiche
J
J
Geenen
V
V
D000328:Adult; D002460:Cell Line; D003907:Dexamethasone / Q000494:pharmacology*; D006801:Humans; D053590:Interleukin 1 Receptor Antagonist Protein; D016753:Interleukin-10 / Q000096:biosynthesis / Q000494:pharmacology*; D008070:Lipopolysaccharides / Q000494:pharmacology; D008297:Male; D008875:Middle Aged; D009000:Monocytes / Q000737:chemistry / Q000187:drug effects*; D011965:Receptors, Glucocorticoid / Q000032:analysis*; D012795:Sialoglycoproteins / Q000096:biosynthesis; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis / Q000494:pharmacology*
C507763:IL1RN protein, human; D053590:Interleukin 1 Receptor Antagonist Protein; D008070:Lipopolysaccharides; D011965:Receptors, Glucocorticoid; D012795:Sialoglycoproteins; D014409:Tumor Necrosis Factor-alpha; D016753:Interleukin-10; D003907:Dexamethasone