Mechanobiology & Soft Matter Group, Interfaces and Complex Fluids Laboratory, Research Institute for Biosciences, University of Mons, 7000 Mons, Belgium.
Laboratory of Neuroscience, Research Institute for Biosciences, Faculty of Medicine and Pharmacy, University of Mons, 7000 Mons, Belgium.
ACS Chem Neurosci. 2021 Oct 20;12(20):3885-3897. doi: 10.1021/acschemneuro.1c00488. Epub 2021 Oct 6.
Deformation, compression, or stretching of brain tissues cause diffuse axonal injury (DAI) and induce structural and functional alterations of astrocytes, the most abundant cell type in the brain. To gain further insight into the role of mechanically activated astrocytes on neuronal networks, this study was designed to investigate whether cytokines released by mechanically activated astrocytes can affect the growth and synaptic connections of cortical neuronal networks. Astrocytes were cultivated on elastic membranes and subjected to repetitive mechanical insults, whereas well-defined protein micropatterns were used to form standardized neuronal networks. GFAP staining showed that astrocytes were mechanically activated after two cycles of stretch and mesoscale discovery assays indicated that injured astrocytes released four major cytokines. To understand the role of these cytokines, neuronal networks were cultured with the supernatant of healthy or mechanically activated astrocytes, and the individual contribution of the proinflammatory cytokine tumor necrosis factor-α (TNF-α) was studied. We found that the supernatant of two-cycle stretched astrocytes decreased presynaptic terminals and indicated that TNF-α must be considered a key player of the synaptic loss. Furthermore, our results indicate that cytokines released by injured astrocytes significantly modulate the balance between TNFR1 and TNFR2 receptors by enhancing R2 receptors. We demonstrated that TNF-α is not involved in this process, suggesting a predominant role of other secreted cytokines. Together, these results contribute to a better understanding of the consequences of repetitive astrocyte deformations and highlight the role of inflammatory signaling pathways in synaptic plasticity and modulation of TNFR1 and TNFR2 receptors.
脑组织的变形、压缩或拉伸会导致弥漫性轴索损伤（DAI），并引起星形胶质细胞的结构和功能改变，星形胶质细胞是大脑中最丰富的细胞类型。为了更深入地了解机械激活的星形胶质细胞在神经元网络中的作用，本研究旨在探讨机械激活的星形胶质细胞释放的细胞因子是否会影响皮质神经元网络的生长和突触连接。星形胶质细胞在弹性膜上培养，并受到重复的机械刺激，同时使用明确的蛋白质微图案来形成标准化的神经元网络。GFAP 染色显示，星形胶质细胞在两次拉伸循环后被机械激活，而中尺度发现测定表明受损的星形胶质细胞释放了四种主要细胞因子。为了了解这些细胞因子的作用，将神经元网络与健康或机械激活的星形胶质细胞的上清液一起培养，并研究了促炎细胞因子肿瘤坏死因子-α（TNF-α）的单独作用。我们发现，两轮拉伸星形胶质细胞的上清液减少了突触前末梢，并表明 TNF-α必须被视为突触丢失的关键因素。此外，我们的结果表明，受损星形胶质细胞释放的细胞因子通过增强 R2 受体显著调节 TNFR1 和 TNFR2 受体之间的平衡。我们证明 TNF-α不参与这个过程，表明其他分泌的细胞因子起着主要作用。总之，这些结果有助于更好地理解重复星形胶质细胞变形的后果，并强调炎症信号通路在突触可塑性和 TNFR1 和 TNFR2 受体调节中的作用。
