Cholesterol homeostasis in pathogenesis of DR

胆固醇动态平衡和新陈代谢紊乱会导致高胆固醇 病变组织中的浓度和胆固醇晶体(CC)的形成。抄送通常是 在传统的组织学/免疫组织化学中被忽视的是用于组织处理的乙醇， 可以将它们溶解。这掩盖了CC的存在和可能参与的致病 机械装置。用扫描电子显微镜(SEM)观察未经硝酸甘油制备的组织 乙醇脱水步骤，我们鉴定了CC：I)在视网膜之间的“脂池”中的存在 糖尿病小鼠的色素上皮(RPE)和光感受器(PR)自由循环 血液；以及iii)在糖尿病受试者的循环单核细胞内。因为CC非常稳定 从生理上讲，它们不容易在体内溶解，成为 慢性炎症。CC被先天免疫系统识别为异物 因为它们的形状、坚固性和不能被溶解。此外，CC还可以诱导 炎症通过NLRP3炎性小体激活。这些小说初步出版了 研究使我们提出了以下假设(见图1示意图)：糖尿病- 导致1)全身胆固醇稳态的破坏，2)血视网膜屏障功能的破坏； III)SIRT1、LXR和CYP46A1的表达改变视网膜胆固醇稳态，导致 关键部位的CC形成：RPE、PR、单核/巨噬细胞和循环中 影响内皮细胞。这种CC的形成导致细胞内和细胞外的补体 NLRP3炎性小体的激活和启动以激活和释放高密度脂蛋白 破坏促炎细胞因子，促进博士的发展为了验证这一假说， 我们提出以下具体目标：AIM1：确定视网膜的时间变化 胆固醇的积累导致CC的形成。目标2：检验糖尿病-- 诱导的胆固醇在视网膜和视网膜中的积聚和CC的形成 单核/巨噬细胞诱导细胞内外补体活化 触发NLRP3炎症体和IL-1β的产生。目标3：检验LXR的假设 α-环糊精激活和直接封存胆固醇可抑制CC诱导的胆固醇 糖尿病视网膜和糖尿病视网膜中复合体和NLRP3炎性小体的形成 单核/巨噬细胞，从而预防慢性炎症和发展的DR。 影响：该项目的成功完成将导致确定一个全新的 CC诱导的复合体和NLRP3炎性小体形成的途径 药理上有针对性地预防DR。

Disruptions in cholesterol homeostasis and metabolism can lead to high cholesterol concentrations in diseased tissue and the formation of cholesterol crystals (CC). CC are often overlooked in traditional histo/immunohistochemistry as the ethanol, used for tissue processing, can dissolve them. This masks CC presence and potential involvement in pathogenic mechanisms. Using Scanning Electron Microscopy (SEM) of tissues prepared without an ethanol dehydration step, we identified the presence of CC: i) in “lipid pools” between retinal pigment epithelium (RPE) and photoreceptors (PR); ii) circulating freely in diabetic murine blood; and iii) within circulating monocytes of diabetic human subjects. Since CC are very stable physiologically and are not easily amenable to dissolving in vivo, they become a source of chronic inflammation. CC are recognized by the innate immune system as foreign bodies because of their shape, firmness, and inability to be dissolved. Moreover, CC also induce inflammation via the NLRP3 inflammasome activation. These novel preliminary and published studies have led us to propose the following hypothesis (see schematic in Fig.1): Diabetes- induced disruption of i) systemic cholesterol homeostasis, ii) blood retinal barrier function; and iii) SIRT1, LXR and CYP46A1 expression alters retinal cholesterol homeostasis leading to CC formation within key locations: RPE, PR, monocytes/macrophages, and in the circulation affecting the endothelium. This CC formation results in intra- and extracellular complement activation and priming of the NLRP3 inflammasome for its activation and release of highly damaging pro-inflammatory cytokines, promoting development of DR. To test this hypothesis, we propose the following Specific Aims: Aim1: To determine the temporal changes in retinal cholesterol accumulation that lead to CC formation. Aim 2: To test the hypothesis that diabetes- induced cholesterol accumulation and CC formation in the retina and in monocytes/macrophages induces activation of intracellular and extracellular complement to trigger the NLRP3 inflammasome and IL-1β production. Aim 3: To test the hypothesis that LXR activation and direct sequestration of cholesterol by alpha-cyclodextrin can inhibit CC-induced complosome and NLRP3 inflammasome formation in the diabetic retina and in monocytes/macrophages cells, thus preventing chronic inflammation and development of DR. Impact: The successful completion of this project will result in identifying an entirely novel pathway in which CC-induced complosome and NLRP3 inflammasome formation that can be pharmacologically targeted to prevent DR.