Fernandez-Lizarbe Sara, Pascual Maria, Gascon M Soledad, Blanco Ana, Guerri Consuelo
Department of Cellular Pathology, Centro de Investigación Príncipe Felipe, Avda. Autopista del Saler 16, 46013 Valencia, Spain.
Mol Immunol. 2008 Apr;45(7):2007-16. doi: 10.1016/j.molimm.2007.10.025. Epub 2007 Dec 3.
Toll-like receptors (TLRs) response is critical in innate resistance to infection. Alcohol consumption has been shown to suppress the inflammatory response mediated through TLR4, down regulating the production of inflammatory cytokines. We recently reported that low concentrations of ethanol activate TLR4 signaling in astrocytes and triggers neuroinflammation. Because macrophages are important cells in innate immunity, we investigate whether low concentrations of ethanol could stimulate the TLR4 signaling response in murine RAW 264.7 macrophages, and the mechanism involved in the ethanol-induced TLR4 activation. Our results show that while ethanol, at high concentrations (100mM) or in the presence of the LPS, suppresses the TLR4 response, low to moderate levels (10-50mM) activate the TLR4 response and triggers the stimulation of the mitogen-activated protein kinases (MAPKs) and the transcription factor NF-kappaB pathways, leading to the production of nitric oxide (NO) and inflammatory cytokines. Pre-treatment with anti-TLR4 Abs abolishes the effects of ethanol on the production of cytokines. We also present evidence that stimulation with either ethanol or LPS induces translocation and clustering of TLR4 and signaling molecules (IRAK and MAPKs) into lipid rafts. Treatment with either streptolysin-O or saponin, lipid rafts disrupting agents, abolishes the ethanol-induced activation of the TLR4/IL-1RI signaling pathway. In summary, the present results demonstrate that low to moderate concentrations of ethanol are capable of stimulating TLR4/IL-1RI response, and provide evidence of a novel mechanism by which ethanol, through its interaction with membrane rafts, can promote TLR4/IL-1RI recruitment and signaling.
Toll样受体（TLRs）反应在先天性抗感染中至关重要。饮酒已被证明可抑制通过TLR4介导的炎症反应，下调炎性细胞因子的产生。我们最近报道，低浓度乙醇可激活星形胶质细胞中的TLR4信号并引发神经炎症。由于巨噬细胞是先天性免疫中的重要细胞，我们研究了低浓度乙醇是否能刺激小鼠RAW 264.7巨噬细胞中的TLR4信号反应以及乙醇诱导TLR4激活的机制。我们的结果表明，虽然高浓度（100mM）乙醇或存在脂多糖（LPS）时会抑制TLR4反应，但低至中等水平（10 - 50mM）会激活TLR4反应并触发丝裂原活化蛋白激酶（MAPKs）和转录因子核因子κB（NF-κB）途径的刺激，导致一氧化氮（NO）和炎性细胞因子的产生。用抗TLR4抗体预处理可消除乙醇对细胞因子产生的影响。我们还提供证据表明，用乙醇或LPS刺激会诱导TLR4和信号分子（白细胞介素-1受体相关激酶（IRAK）和MAPKs）转位并聚集到脂筏中。用脂筏破坏剂链球菌溶血素-O或皂角苷处理可消除乙醇诱导的TLR4/白细胞介素-1受体（IL-1RI）信号通路的激活。总之，目前的结果表明，低至中等浓度的乙醇能够刺激TLR4/IL-1RI反应，并提供了一种新机制的证据，即乙醇通过与膜筏相互作用可促进TLR4/IL-1RI的募集和信号传导。
