DataSheet_1_Interleukin 10 Restores Lipopolysaccharide-Induced Alterations in Synaptic Plasticity Probed by Repetitive Magnetic Stimulation.docx

Systemic inflammation is associated with alterations in complex brain functions such as learning and memory. However, diagnostic approaches to functionally assess and quantify inflammation-associated alterations in synaptic plasticity are not well-established. In previous work, we demonstrated that bacterial lipopolysaccharide (LPS)-induced systemic inflammation alters the ability of hippocampal neurons to express synaptic plasticity, i.e., the long-term potentiation (LTP) of excitatory neurotransmission. Here, we tested whether synaptic plasticity induced by repetitive magnetic stimulation (rMS), a non-invasive brain stimulation technique used in clinical practice, is affected by LPS-induced inflammation. Specifically, we explored brain tissue cultures to learn more about the direct effects of LPS on neural tissue, and we tested for the plasticity-restoring effects of the anti-inflammatory cytokine interleukin 10 (IL10). As shown previously, 10 Hz repetitive magnetic stimulation (rMS) of organotypic entorhino-hippocampal tissue cultures induced a robust increase in excitatory neurotransmission onto CA1 pyramidal neurons. Furthermore, LPS-treated tissue cultures did not express rMS-induced synaptic plasticity. Live-cell microscopy in tissue cultures prepared from a novel transgenic reporter mouse line [C57BL/6-Tg(TNFa-eGFP)] confirms that ex vivo LPS administration triggers microglial tumor necrosis factor alpha (TNFα) expression, which is ameliorated in the presence of IL10. Consistent with this observation, IL10 hampers the LPS-induced increase in TNFα, IL6, IL1β, and IFNγ and restores the ability of neurons to express rMS-induced synaptic plasticity in the presence of LPS. These findings establish organotypic tissue cultures as a suitable model for studying inflammation-induced alterations in synaptic plasticity, thus providing a biological basis for the diagnostic use of transcranial magnetic stimulation in the context of brain inflammation.

全身性炎症与学习、记忆等复杂脑功能的改变密切相关。然而，用于功能评估并量化炎症相关突触可塑性改变的诊断方法尚未完善。在既往研究中，我们证实细菌脂多糖（lipopolysaccharide, LPS）诱导的全身性炎症会改变海马神经元表达突触可塑性的能力，即兴奋性神经传递的长时程增强（long-term potentiation, LTP）。本研究旨在探讨重复经颅磁刺激（repetitive magnetic stimulation, rMS）——一种已应用于临床的无创脑刺激技术——所诱导的突触可塑性是否会受到LPS诱导炎症的影响。具体而言，我们通过脑组织培养探究了LPS对神经组织的直接作用，并测试了抗炎细胞因子白细胞介素10（interleukin 10, IL10）恢复突触可塑性的效果。如既往研究所示，对器官型内嗅皮层-海马组织培养施加10Hz重复经颅磁刺激，可显著增强CA1区锥体神经元的兴奋性神经传递。此外，经LPS处理的组织培养无法表达rMS诱导的突触可塑性。采用新型转基因报告小鼠株[C57BL/6-Tg(TNFa-eGFP)]制备的组织培养进行活细胞显微镜成像，证实离体给予LPS可触发小胶质细胞肿瘤坏死因子α（tumor necrosis factor alpha, TNFα）的表达，而IL10的存在可缓解这一现象。与该结果一致的是，IL10可抑制LPS诱导的TNFα、IL6、IL1β及IFNγ水平升高，并在LPS存在的情况下恢复神经元表达rMS诱导突触可塑性的能力。本研究证实器官型组织培养可作为研究炎症诱导突触可塑性改变的合适模型，从而为脑炎症背景下经颅磁刺激的临床诊断应用提供了生物学基础。