Sun Zhenghao, Li Xuewang, Yang Liu, Dong Xianan, Han Yuli, Li Yan, Luo Jing, Li Weizu
Department of Pharmacology, Basic Medicine College, Key Laboratory of Anti-Inflammatory and Immunopharmacology, Ministry of Education, Anhui Medical University, Hefei, 230032, Anhui, China.
Department of Neurosurgery, The First Affiliated Hospital of Anhui Medical University, Hefei, 230032, Anhui, China.
Mol Neurobiol. 2022 May;59(5):3183-3205. doi: 10.1007/s12035-021-02717-y. Epub 2022 Mar 14.
The level of lipopolysaccharide (LPS) is higher in the blood and brains of patients with Alzheimer's disease (AD), and this phenomenon is strongly linked to AD-related neuronal damage and β-amyloid (Aβ) generation. However, the mechanism by which LPS causes neuronal damage has still not been fully clarified. Oxidative stress, neuroinflammation, and Ca overload are regarded as important factors influencing AD. NADPH oxidase 2 (NOX2) and the NOD-like receptor family protein 1 (NLRP1) inflammasome play important roles in promoting oxidative stress and inflammation in neurons. Ca overload can activate calcineurin (CN), which further dephosphorylates nuclear factor of activated T cells (NFAT), leading to its translocation into the nucleus to regulate gene transcription. In the present study, LPS (250 µg/kg) exposure for 14 days was used to induce cognitive dysfunction in mice and LPS (20 µg/ml) exposure for 48 h was used to induce neuronal damage in HT22 cells. The results showed that LPS exposure activated phospholipase C (PLC), CN, and NFAT1; increased the expressions of NOX2- and NLRP1-related proteins; and promoted neuronal damage and Aβ deposition in mice and HT22 cells. However, treatment with 2-APB (SOCE inhibitor), apocynin (NOX inhibitor), or tempol (reactive oxygen species scavenger) significantly reversed these LPS-induced changes, and improved neuronal damage and Aβ deposition. Moreover, LPS exposure promoted PLC phosphorylation, increased the level of inositol-1,4,5-triphosphate, elevated the intracellular Ca concentration ([Ca]), and disrupted [Ca] homeostasis in HT22 cells. These data indicated that the activation of SOCE-mediated NFAT1-NOX2-NLRP1 inflammasome involves in LPS-induced neuronal damage and Aβ generation.
阿尔茨海默病（AD）患者血液和大脑中的脂多糖（LPS）水平较高，且这种现象与AD相关的神经元损伤和β-淀粉样蛋白（Aβ）生成密切相关。然而，LPS导致神经元损伤的机制仍未完全阐明。氧化应激、神经炎症和钙超载被认为是影响AD的重要因素。烟酰胺腺嘌呤二核苷酸磷酸（NADPH）氧化酶2（NOX2）和NOD样受体家族蛋白1（NLRP1）炎性小体在促进神经元氧化应激和炎症中起重要作用。钙超载可激活钙调神经磷酸酶（CN），后者进一步使活化T细胞核因子（NFAT）去磷酸化，导致其转位至细胞核以调节基因转录。在本研究中，采用14天暴露于LPS（250 μg/kg）来诱导小鼠认知功能障碍，采用48小时暴露于LPS（20 μg/ml）来诱导HT22细胞神经元损伤。结果显示，LPS暴露激活了磷脂酶C（PLC）、CN和NFAT1；增加了NOX2和NLRP1相关蛋白的表达；并促进了小鼠和HT22细胞中的神经元损伤和Aβ沉积。然而，用2-氨基乙氧基二苯硼酸（2-APB，一种储存性钙内流（SOCE）抑制剂）、阿朴吗啡（一种NOX抑制剂）或Tempol（一种活性氧清除剂）进行处理可显著逆转这些LPS诱导的变化，并改善神经元损伤和Aβ沉积。此外，LPS暴露促进了PLC磷酸化，增加了肌醇-1,4,5-三磷酸水平，提高了细胞内钙浓度（[Ca]），并破坏了HT22细胞中的[Ca]稳态。这些数据表明，SOCE介导的NFAT1-NOX2-NLRP1炎性小体的激活参与了LPS诱导的神经元损伤和Aβ生成。
