The Marine Biomedical Research Institute, Guangdong Medical University, Zhanjiang 524023, China; Southern Marine Science and Engineering Guangdong Laboratory (Zhanjiang), Zhanjiang 524023, China; The Marine Biomedical Research Institute of Guangdong Zhanjiang, Zhanjiang 524023, China.
Department of Pharmacology, Guangdong Medical University, Zhanjiang 524023, China.
Life Sci. 2021 Feb 15;267:118943. doi: 10.1016/j.lfs.2020.118943. Epub 2021 Jan 4.
Astaxanthin is a natural carotenoid, can readily cross the blood-brain barrier and exerts a powerful neuroprotective effect. In this study, experiments were performed to explore the underlying molecular mechanisms of which Astaxanthin inhibiting the microglia M1 activation.
BV2 cells and mice were pre-treated with Astaxanthin and treated by Lipopolysaccharide (LPS). The expressions of M1-related factors (pro-inflammatory cytokines and M1 markers) were measured by RT-qPCR and western blot. The target association between miR-31-5p and Numb was explored via luciferase activity assay. MiR-31-5p mimic was transfected into BV2 cells, then the cells were treated with Astaxanthin in combination with LPS. The expression of M1-related factors and Notch pathway-related molecules were measured via RT-qPCR, western blot and immunofluorescence assay.
Precondition of BV2 cells with Astaxanthin inhibited the expression of M1-related factors triggered by LPS. In addition, Astaxanthin decreased the number of Iba1-positive microglia and downregulated the levels of M1-related factors in hippocampus in LPS-treated mice. Further investigation revealed that Astaxanthin-mediated suppression of M1-related factors levels was reversed by miR-31-5p mimic in BV2 cells stimulated by LPS. Subsequently, we verified that miR-31-5p repressed Numb expression by binding to the 3'-UTR of Numb mRNA. Also, Astaxanthin suppressed the expression of Notch1, Hes1 and Hes5 and improved the expression of Numb in BV2 cells challenged by LPS, but this alteration can be reversed by miR-31-5p mimic.
Our study demonstrated that down-regulating miR-31-5p by Astaxanthin could be a potential therapeutic approach to suppress neuroinflammation via regulating microglia M1 activation.
虾青素是一种天然类胡萝卜素，能够轻易穿过血脑屏障，并发挥强大的神经保护作用。本研究旨在探讨虾青素抑制小胶质细胞 M1 活化的潜在分子机制。
用虾青素预处理 BV2 细胞和小鼠，并用脂多糖（LPS）处理。通过 RT-qPCR 和 Western blot 测量 M1 相关因子（促炎细胞因子和 M1 标志物）的表达。通过荧光素酶活性测定法探索 miR-31-5p 与 Numb 之间的靶标关联。将 miR-31-5p 模拟物转染到 BV2 细胞中，然后用虾青素联合 LPS 处理这些细胞。通过 RT-qPCR、Western blot 和免疫荧光测定法测量 M1 相关因子和 Notch 通路相关分子的表达。
用虾青素预处理 BV2 细胞可抑制 LPS 引发的 M1 相关因子的表达。此外，虾青素降低了 LPS 处理小鼠海马中 Iba1 阳性小胶质细胞的数量，并下调了 M1 相关因子的水平。进一步研究表明，在 LPS 刺激的 BV2 细胞中，miR-31-5p 模拟物逆转了虾青素介导的 M1 相关因子水平的抑制。随后，我们证实 miR-31-5p 通过与 Numb mRNA 的 3'-UTR 结合来抑制 Numb 表达。此外，虾青素抑制 LPS 作用下的 BV2 细胞中 Notch1、Hes1 和 Hes5 的表达，并改善 Numb 的表达，但这种变化可被 miR-31-5p 模拟物逆转。
我们的研究表明，通过虾青素下调 miR-31-5p 可能是通过调节小胶质细胞 M1 活化来抑制神经炎症的潜在治疗方法。
