Lipari Cristiana Lucia Rita, Patti Aurora, Conti-Nibali Stefano, Messina Angela Anna, Magrì Andrea, Sortino Maria Angela, Merlo Sara
Department of Biomedical and Biotechnological Sciences, University of Catania, Via S. Sofia 97, 95123, Catania, Italy.
Department of Biological, Geological and Environmental Sciences, University of Catania, Via Androne 81, 95124, Catania, Italy.
J Transl Med. 2025 Sep 24;23(1):1012. doi: 10.1186/s12967-025-07044-7.
Early Alzheimer's disease (AD) is characterized by anti-inflammatory microglial responses to the beta amyloid peptide (Aβ), which later switch to pro-inflammatory. Such transition is relevant to disease progression and can be affected by concurrent insults, such as hypoxia (HY). This study explored whether a mild hypoxic stimulus could anticipate the microglial phenotypic switch, focusing in particular on involvement of SIRT1 and mitochondrial function.
HMC3 human microglia were polarized to an anti-inflammatory phenotype by 3 h of exposure to 0.2 μM of Aβ42 to mimic early AD and transferred to a hypoxic chamber with 3% of O for 1 h. Effects on microglial activation were investigated by analysis of the SIRT1-BDNF axis activation and enzymatic and ELISA assays of inflammatory markers. Mitochondrial function and morphology were analyzed by high resolution respirometry and laser scanning confocal microscopy.
Hypoxia (HY) prevented the Aβ42-induced early induction of SIRT1 translocation and BDNF release and significantly increased caspase 1 and NF-kB activity. Moreover, mitochondrial oxygen flows evaluated by high resolution respirometry were significantly reduced, while mitochondrial area, perimeter and branching were increased by Aβ42 + HY, compared to Aβ alone. These changes were contrasted by both melatonin (1 μM) and naringenin (10 μM), natural substances able to induce SIRT1. However, use of the selective SIRT1 inhibitor EX-527 (5 μM) suggested only a partial involvement for SIRT1 in the observed effects, prevalent for naringenin.
Our results suggest that mild hypoxic insults during early asymptomatic stages of AD can pose as a risk factor for an accelerated progression of the disease and show the benefits of SIRT1 induction strategies, including use of natural substances like melatonin and naringenin.
早期阿尔茨海默病（AD）的特征是小胶质细胞对β淀粉样肽（Aβ）产生抗炎反应，随后转变为促炎反应。这种转变与疾病进展相关，并且可能受到诸如缺氧（HY）等并发损伤的影响。本研究探讨了轻度缺氧刺激是否能预测小胶质细胞表型转换，特别关注沉默调节蛋白1（SIRT1）和线粒体功能的参与情况。
通过将人小胶质细胞系HMC3暴露于0.2μM的Aβ42 3小时以模拟早期AD，使其极化至抗炎表型，然后转移至含3%氧气的缺氧箱中1小时。通过分析SIRT1-脑源性神经营养因子（BDNF）轴的激活以及炎症标志物的酶学和酶联免疫吸附测定（ELISA）来研究对小胶质细胞活化的影响。通过高分辨率呼吸测定法和激光扫描共聚焦显微镜分析线粒体功能和形态。
缺氧（HY）阻止了Aβ42诱导的SIRT1易位和BDNF释放的早期诱导，并显著增加了半胱天冬酶1和核因子κB（NF-κB）的活性。此外，与单独使用Aβ相比，通过高分辨率呼吸测定法评估的线粒体氧流量显著降低，而Aβ42 + HY使线粒体面积、周长和分支增加。褪黑素（1μM）和柚皮素（10μM）这两种能够诱导SIRT1的天然物质可对抗这些变化。然而，使用选择性SIRT1抑制剂EX-527（5μM）表明，SIRT1仅部分参与了观察到的效应，柚皮素的作用更为显著。
我们的结果表明，AD早期无症状阶段的轻度缺氧损伤可能是疾病加速进展的危险因素，并显示了诱导SIRT1策略的益处，包括使用褪黑素和柚皮素等天然物质。
