Cyclodextrin promotes atherosclerosis regression via LXR activation (II)

Atherosclerosis is an inflammatory disease linked to elevated blood cholesterol levels. Despite ongoing advances in the prevention and treatment of atherosclerosis, cardiovascular disease remains the leading cause of death worldwide. Continuous retention of apolipoprotein B-containing lipoproteins in the subendothelial space causes a local overabundance of free cholesterol. Since cholesterol accumulation and deposition of cholesterol crystals (CCs) triggers a complex inflammatory response, we tested the therapeutic potential of increasing cholesterol solubility in experimental atherogenesis. Here we show that treatment of murine atherosclerosis with the cyclic oligosaccharide 2-hydroxypropyl-beta-cyclodextrin (CD), a compound that solubilizes lipophilic substances, reduced atherosclerotic plaque size, cholesterol crystal load and promoted plaque regression even under continuing Western diet. CD solubilized CCs and promoted cholesterylester and oxysterol production in macrophages leading to liver X receptor (LXR)-mediated transcriptional reprogramming. CD increased cholesterol efflux from macrophages and substantially augmented reverse cholesterol transport in vivo. Furthermore, CD reduced proinflammatory cytokines in vivo and decreased macrophage responsiveness towards TLR and inflammasome activation. Since CD treatment in humans is safe and CD beneficially affects key pathogenetic factors in atherogenesis it may thus be used clinically to prevent or treat human atherosclerosis. We hypothesize that cyclodextrin (CD) reprograms macrophage gene expression by activating LXR transcription factors. Therefore, we used M-CSF derived bone-marrow macrophages from wt and LXRa/LXRb dko mice, which were loaded with cholesterol crystals for 3h or left untreated. Excess cholesterol crystals were washed away and the BMDMs were treated for 4h with 10 mM of CD prior to gene expression analysis.动脉粥样硬化（Atherosclerosis）是一种与血液胆固醇水平升高相关的炎症性疾病。尽管动脉粥样硬化的预防与治疗技术持续取得进展，心血管疾病仍是全球范围内的首要致死病因。载脂蛋白B（apolipoprotein B）包裹的脂蛋白在内皮下间隙的持续滞留，会导致局部游离胆固醇过量蓄积。鉴于胆固醇蓄积与胆固醇晶体（cholesterol crystals, CCs）的沉积可触发复杂的炎症应答，我们评估了提升胆固醇溶解性在实验性动脉粥样硬化中的治疗潜力。本研究表明，使用环寡糖2-羟丙基-β-环糊精（2-hydroxypropyl-beta-cyclodextrin, CD）——一种可增溶脂溶性物质的化合物——干预小鼠动脉粥样硬化，即使在持续喂食西方饮食的条件下，仍可缩小动脉粥样硬化斑块体积、降低胆固醇晶体负荷，并促进斑块消退。CD可溶解胆固醇晶体，并促进巨噬细胞内胆固醇酯与氧固醇的生成，进而介导肝X受体（liver X receptor, LXR）依赖的转录重编程。CD可增强巨噬细胞的胆固醇外流能力，并在体内显著提升逆胆固醇转运效率。此外，CD可在体内降低促炎细胞因子水平，减弱巨噬细胞对Toll样受体（TLR）与炎症小体激活的应答反应。鉴于CD在人体中使用安全，且可对动脉粥样硬化发生发展的关键致病因素产生有益影响，其有望在临床中用于预防或治疗人类动脉粥样硬化。我们提出假说：环糊精（cyclodextrin, CD）可通过激活LXR转录因子，重编程巨噬细胞的基因表达。为此，我们使用了野生型与LXRα/LXRβ双敲除小鼠的M-CSF诱导骨髓来源巨噬细胞（bone-marrow derived macrophages, BMDMs），将其用胆固醇晶体负载3小时或不做处理。移除过量的胆固醇晶体后，在进行基因表达分析前，将骨髓来源巨噬细胞用10 mM的CD处理4小时。