Using Human iPSC Models to Determine the Mechanism of Inflammation-Induced Disruption of Dopamine Neurotransmission

项目摘要 目前的提案将使用创新的干细胞技术来探索炎症的机制， 影响多巴胺（DA）神经传递，特别关注炎症对突触前DA的影响 囊泡炎症被认为在约30%的抑郁症患者中起关键的病理生理作用， 与奖赏回路的影响有关，导致动机缺陷，最终导致快感缺乏。快感缺乏 抑郁症是抑郁症的核心和致残症状，抑郁症是全球残疾的主要原因。研究 实验室动物和人类的研究表明，大脑中炎症的主要目标之一是大脑中的DA。 腹侧纹状体，一个皮质下的大脑区域，已被证明是唯一可接近的外周 炎症介质，包括白细胞介素（IL）-6通过破坏血脑屏障。体内 在非人灵长类动物和啮齿类动物中的微透析证明了给予炎性细胞因子 包括IL-6减少细胞外DA的可用性和释放， 显示在给予炎性细胞因子干扰素-α后纹状体DA周转减少。 然而，目前尚不清楚的是炎症反应的具体细胞和分子机制。 细胞因子如IL-6破坏DA神经传递。我们的初步研究结果表明，在体外IL-6治疗， 人诱导多能干细胞（hiPSC）衍生的DA神经元（其表达IL-6受体）直接 降低DA的可用性，并下调与突触囊泡相关的通路中的基因表达 功能这些效应发生在没有细胞毒性的情况下，基因表达的变化是 Baricitinib是一种FDA批准的药物，在埃默里大学开发，通过 抑制Janus激酶1和2。在目前的项目中，我们的目标是进一步阐明机制， IL-6使用人iPSC衍生的DA神经元影响DA神经传递。具体来说，我们将确定 在存在或不存在baricitinib的情况下，IL-6对hiPSC衍生的DA中突触囊泡功能的影响 神经元（Aim 1）。我们将进一步确定IL-6对DRD 2基因选择性剪接的影响， turn可以调节DA神经元的突触囊泡功能（Aim 2）。这些研究还将包括DA神经元 表达与抑郁症相关的DRD 2变体rs 1076560，其与替代DRD 2 拼接综上所述，所提出的实验将为使用 干细胞技术揭示炎症对DA神经传递、脱落 对精神疾病中DA系统缺陷的致病机制有了新的认识，同时提供了一个 药物开发平台与埃默里的药物发现管道一致。

PROJECT SUMMARY The current proposal will use innovative stem cell technology to explore the mechanism(s) by which inflammation affects dopamine (DA) neurotransmission, with a special focus on inflammation's effects on presynaptic DA vesicles. Inflammation is believed to play a pivotal pathophysiologic role in ~30% of depressed patients and is associated with effects on reward circuitry, leading to motivational deficits and ultimately anhedonia. Anhedonia is a core and disabling symptom of depression, which is the leading cause of disability worldwide. Studies in laboratory animals and humans indicate that one of the major targets of inflammation in the brain is DA in the ventral striatum, a subcortical brain region that has been shown to be uniquely accessible to peripheral inflammatory mediators including interleukin (IL)-6 through disruption in the blood brain barrier. In vivo microdialysis in non-human primates and rodents demonstrate that administration of inflammatory cytokines including IL-6 reduces extracellular DA availability and release, and neuroimaging studies in humans demonstrate reduced striatal DA turnover following administration of the inflammatory cytokine interferon-alpha. What remains unknown, however, are the specific cellular and molecular mechanisms by which inflammatory cytokines such as IL-6 disrupt DA neurotransmission. Our preliminary findings indicate that in vitro IL-6 treatment of human induced pluripotent stem cell (hiPSC)-derived DA neurons (which express IL-6 receptors) directly decreases DA availability and downregulates gene expression in pathways associated with synaptic vesicular function. These effects occurred in the absence of cellular toxicity, and the gene expression changes were reversed by baricitinib, an FDA-approved drug that was developed at Emory and blocks IL-6 signaling through inhibition of Janus Kinases 1 and 2. In the current project, we aim to further elucidate the mechanisms by which IL-6 affects DA neurotransmission using human iPSC-derived DA neurons. Specifically, we will determine the impact of IL-6 on synaptic vesicular function in the presence or absence of baricitinib in hiPSC-derived DA neurons (Aim 1). We will further determine the impact of IL-6 on alternative splicing of the DRD2 gene, which in turn can regulate synaptic vesicular function in DA neurons (Aim 2). These studies will also include DA neurons expressing the depression-associated DRD2 variant rs1076560, which is associated with alternate DRD2 splicing. Taken together, the proposed experiments will provide an important proof of principle for the use of stem cell technology to reveal the mechanisms of inflammation's effects on DA neurotransmission, shedding new light on pathogenic mechanisms underlying DA system deficits in psychiatric disorders, while providing a platform for drug development aligned with Emory's drug discovery pipeline.