[Inhibitory effect of dexamethasone on myeloid differentiation factor 88 and tumor necrosis factor-alpha expressions in mouse peritoneal macrophages].

Objective: To study the inhibitory effect of dexamethasone (DEX) on myeloid differentiation factor 88 (MyD88) and tumor necrosis factor-alpha (TNF-alpha) expression in mouse peritoneal macrophages in innate immune response to Penicillium marneffei (PM).

Methods: Mouse peritoneal macrophages were cultured in the presence of heat-inactivated yeast-phase PM with or without DEX, and the protein and mRNA expressions of MyD88 in the macrophages were detected using Western blotting and real-time PCR, respectively. TNF-alpha in the cell culture supernatant was measured with enzyme-linked immunosorbent assay.

Results: DEX suppressed TNF-alpha production by the macrophages co-cultured with PM. The expressions of MyD88 were up-regulated by PM stimulation, whose effect was inhibited by the application of DEX.

Conclusion: The inhibitory effect of DEX on PM-induced proinflammatory responses of the macrophage is directly associated with the inhibition of MyD88 expression.