oxLDL通过TLR4诱导脂质累积和炎症反应促进动脉粥样硬化的分子机制

摘要

Objective · To investigate the possible role of TLR4 signaling pathway in the mediation of atherosclerosis. Methods · TLR4 were knocked down via transfection with TLR4-specific siRNA, and the lipid accumulation was further detected in control and TLR4-knockdown groups by oil red O staining. The expression of CD36 and Lectin-like oxLDL receptor 1 (LOX-1) in macrophages were detected by Western blotting to investigate the role of TLR4 in the expression of oxLDL-related receptors. Cytokines such as interleukin-6 (IL-6), IL-8, monocyte chemoattractant protein 1 (MCP-1), and matrix metalloproteinase-9 (MMP-9) were tested by ELISA to confirm the possible role of TLR4 in the secretion of inflammatory factors. Results · Macrophages (namely CD68+ cells) were found to accumulate within atherosclerosis plaques with TLR4 highly expressed on the surface of macrophages; the stimulation with oxLDL promoted the lipid accumulation (P<0.01), the secretion of inflammatory factors (P<0.01), and the expression of CD36 and LOX-1. The oxLDL-associated expression of CD36 was decreased but the expression of LOX-1 was not affected. The knockdown of TLR4 inhibits oxLDL-induced lipid accumulation (P<0.01)and inflammatory cytokines (IL-6, IL-8, MCP-1 and MMP-9) secretion (P<0.01). Conclusion · TLR4 signaling pathway possibly promotes the lipid accumulation and the secretion of inflammatory factors via up-regulating the expression of CD36 to affect the formation and development of atherosclerosis.%目的·探究TLR4诱导脂质累积和炎症反应从而调控动脉粥样硬化的分子机制.方法·采用TLR4特异性siRNA敲除巨噬细胞,通过油红O染色法比较对照组和实验组中细胞内脂质含量;通过Western blotting检测CD36和血凝素样氧化低密度脂蛋白受体1(LOX-1)表达;通过ELISA检测白介素-6(IL-6)、IL-8、单核细胞趋化蛋白-1(MCP-1)和基质金属蛋白酶-9(MMP-9)等炎症因子的表达.结果·动脉粥样硬化斑块中巨噬细胞(CD68+)大量聚集,且TLR4表达明显上调.oxLDL刺激巨噬细胞,可促进细胞中脂质累积(P<0.01)并导致oxLDL相关受体CD36和LOX-1的表达上调以及炎症因子表达(P<0.01).特异性siRNA敲除TLR4可抑制oxLDL诱导的巨噬细胞内脂质累积(P<0.01)和炎症因子分泌(P<0.01),并影响oxLDL诱导的CD36表达,但对LOX-1表达没有影响.结论·oxLDL/TLR4可能通过上调CD36介导巨噬细胞中脂质累积和炎症反应,从而促进动脉粥样硬化发生和发展.