Borràs Carla, Canyelles Marina, Santos David, Rotllan Noemí, Núñez Estefanía, Vázquez Jesús, Maspoch Daniel, Cano-Sarabia Mary, Carmona-Iragui Maria, Sirisi Sònia, Lleó Alberto, Fortea Juan, Alcolea Daniel, Blanco-Vaca Francisco, Escolà-Gil Joan Carles, Tondo Mireia
Institut de Recerca Sant Pau.
Hospital de la Santa Creu i Sant Pau.
Res Sq. 2024 Dec 23:rs.3.rs-5682870. doi: 10.21203/rs.3.rs-5682870/v1.
In the central nervous system, apolipoprotein (APO) E-containing high-density lipoprotein (HDL)-like particles mediate the transport of glial-derived cholesterol to neurons, which is essential for neuronal membrane remodeling and maintenance of the myelin sheath. Despite this, the role of HDL-like cholesterol trafficking on Alzheimer's disease (AD) pathogenesis remains poorly understood. We aimed to examine cholesterol transport via HDL-like particles in cerebrospinal fluid (CSF) of AD patients compared to control individuals. Additionally, we explored the ability of reconstituted HDL containing different APOE isoforms to regulate cholesterol transport. We evaluated the capacity of CSF HDL-like particles to facilitate radiolabeled unesterified cholesterol efflux from A172 human glioblastoma astrocytes and to deliver cholesterol to SH-SY5Y human neuronal cells. The HDL-like proteome in the AD and control groups was analyzed by liquid chromatography-mass spectrometry (LC-MS/MS). Reconstituted HDL nanoparticles were prepared by combining phospholipids and cholesterol with human APOE3 or APOE4, followed by radiolabeling with unesterified cholesterol. Our results showed that cholesterol efflux from astrocytes to CSF were similar between AD patients and controls, both under baseline conditions and after activation of ATP-binding cassette transporters A1 and G1. However, CSF HDL-like particle-mediated neuronal cholesterol uptake was significantly reduced in the AD group. LC-MS/MS analysis identified 775 proteins associated with HDL-like particles in both groups, with no major alterations in proteins linked to cholesterol metabolism. However, 27 proteins involved in non-cholesterol-related processes were differentially expressed. Notably, synthetic reconstituted HDL particles containing APOE4 exhibited reduced capacity to deliver cholesterol to neurons compared to those with APOE3. These findings indicate that CSF HDL-like particles from patients with AD demonstrate impaired cholesterol delivery to neurons. Our study highlights APOE4 as a critical contributor to abnormal neuronal cholesterol uptake in AD pathophysiology.
在中枢神经系统中，含载脂蛋白（APO）E的高密度脂蛋白（HDL）样颗粒介导神经胶质细胞衍生的胆固醇向神经元的转运，这对于神经元膜重塑和髓鞘维持至关重要。尽管如此，HDL样胆固醇转运在阿尔茨海默病（AD）发病机制中的作用仍知之甚少。我们旨在研究与对照个体相比，AD患者脑脊液（CSF）中通过HDL样颗粒进行的胆固醇转运情况。此外，我们还探讨了含有不同APOE异构体的重组HDL调节胆固醇转运的能力。我们评估了CSF中HDL样颗粒促进放射性标记的未酯化胆固醇从A172人胶质母细胞瘤星形胶质细胞流出并将胆固醇递送至SH-SY5Y人神经细胞的能力。通过液相色谱-质谱联用（LC-MS/MS）分析AD组和对照组中的HDL样蛋白质组。通过将磷脂和胆固醇与人APOE3或APOE4结合，然后用未酯化胆固醇进行放射性标记，制备重组HDL纳米颗粒。我们的结果表明，在基线条件下以及ATP结合盒转运蛋白A1和G1激活后，AD患者和对照组中星形胶质细胞向CSF的胆固醇流出情况相似。然而，AD组中CSF HDL样颗粒介导的神经元胆固醇摄取显著降低。LC-MS/MS分析在两组中鉴定出775种与HDL样颗粒相关的蛋白质，与胆固醇代谢相关的蛋白质没有重大变化。然而，27种参与非胆固醇相关过程的蛋白质存在差异表达。值得注意的是，与含有APOE3的重组HDL颗粒相比，含有APOE4的合成重组HDL颗粒向神经元递送胆固醇的能力降低。这些发现表明，AD患者的CSF HDL样颗粒向神经元的胆固醇递送受损。我们的研究强调APOE4是AD病理生理学中异常神经元胆固醇摄取的关键因素。
