CXCL16调控ABCA1/ABCG1介导细胞内胆固醇外流在息肉状脉络膜血管病变发病机制中的作用

Polypoidal choroidal vasculopathy (PCV) is the leading cause of blindness among Chinese elderly. Our previous study first indentified that genes in the lipid metabolism especially in reverse cholesterol transport were significantly associated with the risk of PCV, but the the serum high density lipoprotein level was not an independent risk factor. Our preliminary experiment found serum cholesterol efflux capacity of PCV was equal with controls, while the levels of CXCL16, which could regulate intracellular cholesterol efflux of cells, were significantly lower in the aqueous humor and serum of PCV. That might imply CXCL16 could regulate the intracellular cholesterol efflux and involve in the pathogenesis of PCV with unclear mechanism. This study was designed to investigate the association among levels of CXCL16 in aqueous humor and serum, the express of ABCA1/ABCG1 and cholesterol efflux of the macrophage from peripheral blood mononuclear cell in larger sample of PCV; Overexpress or depress the CXCL16 of retina pigment epithelium and choroid vascular endothelial cell, and detect the downstream factors and the changes of intracellular cholesterol efflux; The remodeling of choroidal vessels and the expression of each member in this pathway will be observed in a mice model with gene silence of CXCL16 in RPE. The approval of this study will give the evidence of CXCL16 regulating the intracellular cholesterol efflux mediated by ABCA1/ABCG1 involved in the pathogenesis of PCV.

息肉状脉络膜血管病变(PCV)是我国老年人群多发的致盲性眼病。我们前期发现脂质代谢特别是胆固醇逆转运相关基因参与PCV发病，但血清高密度脂蛋白水平并非其独立危险因素。进一步预实验显示PCV患者血清胆固醇外流能力无异常，而蛋白芯片筛查发现其房水和血清中可调控细胞内胆固醇外流的CXCL16水平均显著降低，提示CXCL16可能通过调控细胞内胆固醇外流参与PCV发病，但机制未明。本项目拟在PCV患者中扩大样本研究房水和血清CXCL16水平、外周血单核细胞来源的巨噬细胞ABCA1/ABCG1表达及胆固醇外流率之间的关联性,同时在人视网膜色素上皮(RPE)、脉络膜血管内皮细胞中过表达和抑制CXCL16观察对下游通路和胆固醇外流的影响；进一步在小鼠体内验证特异性沉默RPE内CXCL16表达对RPE及脉络膜的影响；以期获得CXCL16调控ABCA1/ABCG1介导细胞内胆固醇外流参与PCV发病的可靠证据。

息肉状脉络膜血管病变(PCV)是我国老年人群多发的致盲性眼病。我们在本项目中较大样本验证了PCV患者房水和血清中可调控细胞内胆固醇外流的CXCL16水平均显著降低，但CXCL16基因单核苷酸多态性分析结果显示与PCV发病无关，且扩大样本后PCV患者外周血巨噬细胞的胆固醇外流率与对照组无统计学差异；视网膜色素上皮细胞（RPE）过度表达CXCL16对其下游ABCA1/ABCG1因子和VEGF表达无显著影响，对RPE胆固醇外流无显著影响。在小鼠眼新生血管生成的动物模型中CXCL16亦无法抑制新生血管生成。本项目没有获得CXCL16调控胆固醇外流参与PCV发病的证据，提示调节CXCL16的表达无法用于PCV的临床干预。本项目对PCV的血清脂质代谢谱系分析筛选出血小板活化因子是PCV的脂质学生物标记物，且胆固醇代谢相关因子的弹性蛋白酶解作用参与PCV发生；同时发现年龄相关的ICGA晚期的散在弱荧光点与PCV发病相关，可能是Bruch膜线性脂质沉积。