Glucosylceramide attenuates the inflammatory mediator expression in lipopolysaccharide-stimulated RAW264.7 cells

The positive effect of glucosylceramide (GlcCer) on skin conditions is well known. Recently, there has been increasing interest in the potential antiinflammatory effects of GlcCer due to its efficacy in relieving atopic skin symptoms. However, the role of GlcCer in inflammation has not been investigated completely. Thus, we hypothesized that GlcCer might exhibit the antiinflammatory effects through the inhibition of nuclear factor κB (NF-κB) and mitogen-activated protein kinase (MAPK) signaling. To test this hypothesis, the antiinflammatory effects and signaling mechanisms of GlcCer were investigated in lipopolysaccharide (LPS)-induced RAW 264.7 cells. We report that GlcCer inhibited messenger RNA and protein expression of tissue necrosis factor α and interleukin 1β without cytotoxicity. However, it did not affect interleukin 6 production in LPS-stimulated RAW 264.7 macrophages. Glucosylceramide also suppressed prostaglandin E2 but not nitric oxide production, consistent with its inhibition of cyclooxygenase 2 but not of inducible nitric oxide synthase expression. The molecular mechanism of GlcCer-mediated inhibition of LPS-induced inflammation in RAW 264.7 cells is closely related to suppression of NF-κB p65 subunit nuclear translocation as well as to phosphorylation of extracellular signal-regulated kinase and, in particular, p38 MAPK. In addition, GlcCer did not affect c-Jun N-terminal kinase phosphorylation. In conclusion, GlcCer inhibits LPS-induced inflammation by blocking the nuclear translocation of NF-κB and inhibiting the phosphorylation of extracellular signal-regulated kinase/p38 MAPK pathways in macrophages, suggesting that it might be a promising potential drug candidate for various inflammatory diseases.