25-羟基胆固醇减弱肿瘤坏死因子α诱导的血脑屏障分解体外
25-Hydroxycholesterol attenuates tumor necrosis factor alpha-induced blood-brain barrier breakdown in vitro
影响因子:4.20000
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
摘要
细胞内胆固醇代谢受SREBP-2和LXR信号通路调节。炎症对这些分子机制的影响仍然很少研究，尤其是在血脑屏障（BBB）水平上。肿瘤坏死因子α（TNFα）是与BBB功能障碍相关的促炎细胞因子。因此，我们研究的目的是研究TNFα对BBB胆固醇代谢的影响，重点是其潜在的信号通路。使用人类的体外BBB模型，该模型由人脑样内皮细胞（HBLEC）和脑周细胞（HBP）组成，我们观察到，TNFα通过降解两种细胞类型中的紧密连接蛋白Claudin-5和激活应力信号通路来提高BBB的渗透率。 TNFα还促进胆固醇释放并降低胆固醇的积累和APOE分泌。在HBLEC中，SREBP-2靶标（LDLR和HMGCR）的表达增加，而ABCA1表达降低。在HBP中，仅增加LDLR和ABCA1表达。 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代谢产物。 25-HC预处理减轻TNFα诱导的BBB泄漏，并部分减轻TNFα对ABCA1，LDLR和HMGCR表达的影响。总体而言，我们的结果表明，TNFα通过BBB的LXR/ABCA1非依赖性机制促进胆固醇外排，而它激活了SREBP-2途径。用25-HC的处理部分逆转了TNFα对LXR/SREBP-2途径的影响。我们的研究提供了新的观点，可以更好地理解与神经炎症性疾病中BBB功能障碍和胆固醇代谢相关的脑血管信号传导事件。
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.