Dexamethasone regulates IL-1? and TNF-?-induced interleukin-8 production in human bone marrow stromal and osteoblast-like cells

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Abstract
We have investigated both constitutive- and cytokine-induced secretion of interleukin-8 (IL-8) and its regulation by dexamethasone and 17β-estradiol in normal human bone marrow stromal (HBMS), osteoblast-like cells (hOB), and osteosarcoma MG-63 cells. Although HBMS cells secrete low levels of IL-8 constitutively, treatment with IL-1β and tumor necrosis factor-α (TNF-α) induced IL-8 secretion. Their effects were synergistic but IL-8 production was not affected by 17β-estradiol. Human osteosarcoma MG-63 cells also secreted low levels of IL-8 constitutively; the production was induced by IL-1β and TNF-α and was also not affected by 17β-estradiol. The magnitude of the response to cytokine stimulation of IL-8 in MG-63 cells was much lower than that of HBMS and hOB cells, indicating differences in response in normal and osteoblastic osteosarcoma cells. Dexamethasone (10-7 M) significantly inhibited IL-1β plus TNF-α stimulated IL-8 production in HBMS, MG-63, and hOB cells. The accumulated results demonstrate that IL-8 is secreted by HBMS, MG-63, and hOB cells, suggesting that IL-8 may play a role in the regulation of bone cell function. These data also emphasize the importance of glucocorticoids in controlling cytokine secretion in HBMS, hOB, and MG-63 cells.