Glucocorticoids inhibit production of exosomes containing inflammatory microRNA-155 in lipopolysaccharide-induced macrophage inflammatory responses.

Glucocorticoids are anti-inflammatory agents that are widely used in clinical practice. Increasing evidence has identified exosomes as important mediators in inflammation, but it is unknown whether glucocorticoids regulate exosome secretion and function. In the present study, we observed a reduction of exosome secretion in lipopolysaccharide (LPS)-induced RAW264.7 macrophages following treatment with dexamethasone. Importantly, exosomes isolated from LPS-induced RAW264.7 macrophages increased TNF-α and IL-6 production in RAW264.7 cells. However, this increase was less pronounced following treatment with exosomes isolated from dexamethasone-treated cells. Moreover, dexamethasone decreased expression of pro-inflammatory microRNA-155 in exosomes from LPS-induced RAW264.7 macrophages. We postulate that exosomes are novel targets in the anti-inflammatory effect of glucocorticoids in LPS-induced macrophage inflammatory responses. These findings will benefit the development of new approaches for anti-inflammatory therapeutics. IJCEP