25-羟基胆固醇减轻体外肿瘤坏死因子α诱导的血脑屏障破坏

25-Hydroxycholesterol attenuates tumor necrosis factor alpha-induced blood-brain barrier breakdown in vitro

BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR BASIS OF DISEASE

影响因子:4.2

分区:生物学2区 / 生物物理2区生化与分子生物学3区

发表日期:2024 Dec

作者: Rodrigo Azevedo Loiola, Cindy Nguyen, Shiraz Dib, Julien Saint-Pol, Lucie Dehouck, Emmanuel Sevin, Marie Naudot, Christophe Landry, Jens Pahnke, Caroline Pot, Fabien Gosselet

DOI: 10.1016/j.bbadis.2024.167479

摘要

细胞内胆固醇代谢由SREBP-2和LXR信号通路调控。炎症对这些分子机制的影响尚未充分研究，尤其是在血脑屏障（BBB）层面。肿瘤坏死因子α（TNFα）是一种促炎细胞因子，与BBB功能障碍密切相关。因此，本研究旨在探讨TNFα对BBB胆固醇代谢的影响及其潜在信号通路机制。利用由人脑样内皮细胞（hBLECs）和脑周细胞（HBPs）组成的人类体外BBB模型，我们观察到TNFα通过降解紧密连接蛋白CLAUDIN-5及激活应激信号通路，增加BBB通透性。TNFα还促进胆固醇释放，减少胆固醇堆积和APOE分泌。在hBLECs中，SREBP-2靶基因（LDLR和HMGCR）表达增加，而ABCA1表达降低。在HBPs中，只有LDLR和ABCA1表达增加。TNFα处理还诱导25-羟基胆固醇（25-HC）的产生，这是一种参与免疫反应和细胞内胆固醇代谢的胆固醇代谢产物。25-HC预处理减轻了TNFα引起的BBB渗漏，并部分缓解其对ABCA1、LDLR和HMGCR表达的影响。总体而言，研究结果表明TNFα通过一种非LXR/ABCA1途径促进胆固醇外排，同时激活SREBP-2通路。25-HC的处理部分逆转了TNFα对LXR/SREBP-2通路的影响。该研究为理解神经炎症性疾病中与BBB功能障碍和胆固醇代谢相关的脑血管信号事件提供了新视角。

Abstract

Intracellular cholesterol metabolism is regulated by the SREBP-2 and LXR signaling pathways. The effects of inflammation on these molecular mechanisms remain poorly studied, especially at the blood-brain barrier (BBB) level. Tumor necrosis factor α (TNFα) is a proinflammatory cytokine associated with BBB dysfunction. Therefore, the aim of our study was to investigate the effects of TNFα on BBB cholesterol metabolism, focusing on its underlying signaling pathways. Using a human in vitro BBB model composed of human brain-like endothelial cells (hBLECs) and brain pericytes (HBPs), we observed that TNFα increases BBB permeability by degrading the tight junction protein CLAUDIN-5 and activating stress signaling pathways in both cell types. TNFα also promotes cholesterol release and decreases cholesterol accumulation and APOE secretion. In hBLECs, the expression of SREBP-2 targets (LDLR and HMGCR) is increased, while ABCA1 expression is decreased. In HBPs, only LDLR and ABCA1 expression is increased. TNFα treatment also induces 25-hydroxycholesterol (25-HC) production, a cholesterol metabolite involved in the immune response and intracellular cholesterol metabolism. 25-HC pretreatment attenuates TNFα-induced BBB leakage and partially alleviates the effects of TNFα on ABCA1, LDLR, and HMGCR expression. Overall, our results suggest that TNFα favors cholesterol efflux via an LXR/ABCA1-independent mechanism at the BBB, while it activates the SREBP-2 pathway. Treatment with 25-HC partially reversed the effect of TNFα on the LXR/SREBP-2 pathways. Our study provides novel perspectives for better understanding cerebrovascular signaling events linked to BBB dysfunction and cholesterol metabolism in neuroinflammatory diseases.