Miyabenol a Exhibits Anti-Inflammatory Activity through Down-Regulation of LPS-Induced NF-κB and JAK/STAT Pathways in Raw 264.7 Macrophages

MIYABENOL A 在RAW 264.7細胞株透過干擾LPS 誘導之 NF-κB 及 JAK/STAT 途徑而表現出抗發炎活性

"根據我們之前的研究發現分離自小本山葡萄 （Vitis thunbergii） 的 miyabenol A （濃度由 0.1到 10 μM） 可有效抑制在RAW 264.7細胞株由 LPS 所誘導的一氧化氮 （NO）生成以及誘導型 NO合成酶 （iNOS）的表現, 本篇實驗進一步在轉錄層面探討 miyabenol A抑制 NO生成的分子作用機轉。以 LPS 刺激細胞可引起 NF-κB轉移入細胞核內同時伴隨細胞質中 IκB的裂解, 這些現象可以被 miyabenol A （3 及 10 μM） 所抑制。 LPS同時也增加 c-Jun 的磷酸化及c-Fos轉移入細胞核內的量 （AP-1的兩個主要組成）, 然而 miyabenol A 並不會影響前述活化反應。此外, 由 LPS 所誘導的 JAK-1/STAT-1磷酸化增加也會被 miyabenol A 所抑制。以上結果顯示 miyabenol A 可能透過干擾 LPS 誘導之 NF-κB 及 JAK/STAT 途徑而在 RAW 264.7 細胞株表現出抑制 NO 生成的抗發炎活性。We have previously reported that miyabenol A (a stilbene isolated from the roots of Vitis thunbergii) at concentrations ranged from 0.1 to 10 μM displayed potent anti-inflammatory activity to inhibit lipopolysaccaride (LPS)-stimulated nitric oxide (NO) production and inducible NO synthase (iNOS) expression in RAW 264.7 macrophages. Herein, we further investigated its mechanism of action focusing at the transcription level. Cells stimulated with LPS evoked a significant nuclear translocation of NF-κB, which was associated with cytosolic degradation of IκB. These activating phenomenon were abrogated in the presence of miyabenol A (3 and 10 μM). LPS also triggered AP-1 activation as revealed by increased c-Jun phosphorylation and c-Fos nuclear translocation (two major component of AP-1), but miyabenol A failed to affect this activation process. However, miyabenol A reduced LPS-activated phosphorylations of JAK-1/STAT-1. In summary, miyabenol A may inhibit LPS-mediated inflammatory response through down-regulation of both the NF-κB and JAK/STAT pathways to interrupt iNOS expression in RAW 264.7 macrophages. "