Shikonin inhibits the lipopolysaccharide-induced release of HMGB1 in RAW264.7 cells via IFN and NF-κB signaling pathways

To study the anti-inflammation effect of Shikonin (Shik) and its mechanism, murine macrophage-like RAW264.7 cells (RAW264.7 cells) were divided into control group, LPS group (0.125, 0.25 and 0.5 mu g/ml), LPS (0.125, 025 and 0.5 mu g/ml) plus Shik (0.5, 1 and 2 mu M) group, and Shik (2 mu M) group. After exposure for 24 h, the levels of Interleukin-6 (IL-6), nitric oxide (NO) and Tumor Necrosis Factor-alpha (TNF-alpha) in supernatant were measured with ELISA, the expression of high mobility group box 1(HMGB1) in supernatant and cytoplasm was assayed using gRT-PCR, western blot and immunofluorescence assays, the expression of IFN-beta in cellular and supernatant was assayed by gRT-PCR and ELISA, and the ratio of nuclear to cytoplasm for NF-kappa B protein expression was assayed using western blot. The results of our investigation demonstrated that Shik could reduce significantly the levels of IL-6, NO and TNF-alpha in RAW264.7 cells exposed to LPS (P < 0.05 or P < 0.01). The expression of HMGB1, IFN-beta and the ratio of nuclear to cytoplasm for NF-kappa B protein expression in LPS plus Shik group declined significantly as compared with LPS group (P < 0.05 or P < 0.01). The inhibitors of IFN-beta signaling molecule JAK and NF-kappa B could attenuate significantly the expression of HMGB1 in supernatant. It was found in the present study that Shik could have the anti-inflammatory effects in RAW264.7 cells exposed to LPS, and one of the mechanisms may be the down-regulation of HMGB expression, which was associated with the IFN-beta and NF-kappa B signaling pathways. (C) 2014 Elsevier B.V. All rights reserved.