Department of Physiology and Pharmacology, Pasteur Institute of Iran, Tehran, Iran.
Department of Biology, School of Basic Science, Science and Research Branch, Islamic Azad University, Tehran, Iran.
J Mol Neurosci. 2019 Apr;67(4):495-503. doi: 10.1007/s12031-018-1249-1. Epub 2019 Jan 4.
Soluble amyloid beta (Aβ) oligomers are the most common forms of Aβ in the early stage of Alzheimer's disease (AD). They are highly toxic to the neurons but their capability to activate microglia remains controversial. Microglia develop two distinct phenotypes, classic (M1) and alternative (M2). Tuning of microglia to the alternative (anti-inflammatory) state is of major interest in treatment of neuroinflammatory disease. This study aimed to assess tuning the microglia to produce interferon beta (IFN-β) as an anti-inflammatory cytokine through TLR4 pathway in a rat model of AD. Microglial BV-2 cells were treated with 1 μg/ml lipopolysaccharides (LPS), Monophosphoryl lipid A (MPL), or vehicles for 24 h, and then incubated with Aβ oligomer. After 24 h, cell pellets were harvested and TIR-domain-containing adapter-inducing interferon-β (TRIF), interferon regulatory factor 3 (IRF3), and IFN-β levels were measured. The ligands/vehicle were microinjected into the right ventricle of male Wistar rats every 3 days. Two weeks later, an osmotic pump filled with oligomeric Aβ/vehicle was implanted in the left ventricle. After 2 weeks, TRIF, IRF3, and IFN-β levels were measured in the hippocampal tissue. TNF-α and IFN-β levels were assessed in the hippocampus using immunohistochemistry. The oligomeric Aβ did not change TRIF, IRF3, and IFN-β levels in both cell culture and hippocampal tissue. However, pretreatment with LPS or MPL increased the level of these proteins. BV-2 cells morphologically express M1 state in presence of higher dose of Aβ oligomer (10 μM). Pretreatment with LPS or MPL decreased the TNF-α and increased the number of IFN-β positive cells in the hippocampus of Aβ-treated rats. In conclusion, pretreatment with low dose TLR4 agonists could induce microglia to produce neuroprotective cytokines including IFN-β which may be considered as a potential strategy to combat neuronal degeneration in AD.
可溶性淀粉样蛋白β (Aβ) 寡聚体是阿尔茨海默病 (AD) 早期最常见的 Aβ 形式。它们对神经元具有高度毒性，但激活小胶质细胞的能力仍存在争议。小胶质细胞表现出两种不同的表型，经典 (M1) 和替代 (M2)。将小胶质细胞调节为替代 (抗炎) 状态是治疗神经炎症性疾病的主要关注点。本研究旨在评估通过 TLR4 途径将小胶质细胞调节为产生干扰素-β (IFN-β) 作为抗炎细胞因子，以在 AD 大鼠模型中发挥作用。用 1 μg/ml 脂多糖 (LPS)、单磷酰脂质 A (MPL) 或载体处理 BV-2 细胞 24 小时，然后与 Aβ 寡聚体孵育。24 小时后，收集细胞沉淀并测量 TIR 结构域包含衔接子诱导干扰素-β (TRIF)、干扰素调节因子 3 (IRF3) 和 IFN-β 水平。将配体/载体每隔 3 天微注射到雄性 Wistar 大鼠的右心室中。2 周后，将填充有寡聚体 Aβ/载体的渗透泵植入左心室。2 周后，测量海马组织中的 TRIF、IRF3 和 IFN-β 水平。使用免疫组织化学评估海马组织中的 TNF-α 和 IFN-β 水平。寡聚体 Aβ不会改变细胞培养和海马组织中的 TRIF、IRF3 和 IFN-β 水平。然而，用 LPS 或 MPL 预处理会增加这些蛋白质的水平。在存在较高剂量 Aβ 寡聚体 (10 μM) 的情况下，BV-2 细胞形态上表达 M1 状态。用 LPS 或 MPL 预处理可降低 Aβ 处理大鼠海马组织中的 TNF-α 并增加 IFN-β 阳性细胞的数量。总之，用低剂量 TLR4 激动剂预处理可诱导小胶质细胞产生包括 IFN-β 在内的神经保护性细胞因子，这可能被视为对抗 AD 中神经元变性的潜在策略。
