Cytokine-mediated neurologic disease in COVID-19

项目摘要 新出现的冠状病毒，SARS-CoV-2，已经引起了历史性的呼吸道疾病大流行（COVID-19）。 19）。一个令人惊讶的发现是，轻度和重度COVID-19都与持续的神经系统疾病有关。 症状，甚至在感染消退后。患者表现出各种症状， 注意力，计划和其他执行功能，记忆障碍，或新的精神病。验尸 对COVID-19患者大脑的分析没有发现感染SARS-CoV-2的证据， 薄壁组织然而，COVID-19感染与一系列神经损伤有关，包括梗死， 缺血、血管扩张和缺氧。尸检标本的免疫组织化学显示， SARS-CoV-2感染与血脑屏障（BBB）破坏、血脑屏障前体蛋白水平升高有关。 炎性细胞因子、IL-1β和小胶质细胞活化和结节以及神经元吞噬。在其他神经毒性 病毒感染时，IL-1β通过破坏血脑，促进中枢神经系统炎症 屏障和招募免疫细胞激活小胶质细胞，消除海马体中的突触， 对学习和记忆至关重要的大脑区域。在恢复过程中，IL-1β抑制神经发生，从而限制突触 恢复，并诱导空间记忆缺陷。我们假设SARS期间脑中IL-1β的产生- CoV-2感染通过破坏BBB并促进认知和记忆来增强神经功能障碍 赤字为了研究这一点，我们将使用COVID-19的C57 Bl/6小鼠模型，其中小鼠鼻内注射 感染了B.1.351（β变体），其自然感染小鼠。在目的1中，我们将研究IL-1 R1在 使用脑微血管内皮细胞（BMEC）特异性可诱导Cre交叉的BBB破坏的信号传导 IL-1 R floxed小鼠。我们还将确定IL-1 R1信号传导是否促进BMEC的激活和诱导BMEC的表达。 炎症。在目标2中，我们将探索IL-1 R1信号传导是否通过抑制 突触消除过程中的神经发生首先，我们将确定IL-1 R1对神经发生的影响。 在用B.1.351感染期间，使用神经干细胞（NSC）特异性的、与IL-1 R floxed杂交的可诱导Cre小鼠 小鼠接下来，我们通过NSC检测IL-1 R1信号在海马三突触回路恢复中的作用。 特异性或小胶质细胞特异性Cre-IL-1 R1 floxed小鼠。最后，使用与之前实验相同的小鼠，我们 将对从B.1.351中恢复的小鼠进行行为测试，以检查IL-1 R1的功能影响 发信号。在这个提议中，我们将共同探索神经系统疾病的免疫机制， 在COVID-19期间出现功能障碍。

PROJECT SUMMARY The newly emerged coronavirus, SARS-CoV-2, has caused a historic pandemic of respiratory disease (COVID- 19). One surprising finding, is that both mild and severe COVID-19 is associated with persistent neurological symptoms, even after resolution of infection. Patients present with a variety of symptoms, from deficits in attention, planning, and other executive functions, to memory impairment, or new psychoses. Post-mortem analyses of brains from individuals with COVID-19 did not find evidence of infectious SARS-CoV-2 in the parenchyma. However, COVID-19 infection is associated with an array of neurological injury, including infarcts, ischemia, hemorrhages, and hypoxia. Immunohistochemistry on post-mortem specimens demonstrated that SARS-CoV-2 infection is associated with blood-brain barrier (BBB) disruption, elevated levels of the pro- inflammatory cytokine, IL-1β, and microglial activation and nodules, and neuronophagia. In other neurovirulent viral infections, IL-1β promotes inflammation in the central nervous system via disruption of the blood-brain barrier and recruitment of immune cells that activate microglia, which eliminate synapses in the hippocampus, a brain region critical for learning and memory. During recovery, IL-1β inhibits neurogenesis, which limits synapse recovery, and induces spatial memory defects. We hypothesize that IL-1β production in the brain during SARS- CoV-2 infection potentiates neurological dysfunction by disrupting the BBB and promoting cognitive and memory deficits. To investigate this, we will use a C57Bl/6 mouse model of COVID-19, in which mice are intranasally infected with B.1.351 (Beta variant), which naturally infects mice. In Aim 1, we will investigate the role of IL-1R1 signaling on BBB disruption using a brain microvascular endothelial cell (BMEC) specific inducible Cre crossed to IL-1R floxed mice. We will also determine if IL-1R1 signaling promotes activation of BMECs and the induction of inflammation. In Aim 2, we will explore if IL-1R1 signaling impacts cognition and memory via inhibition of neurogenesis within ongoing synapse elimination. First, we will determine the impact of IL-1R1 on neurogenesis during infection with B.1.351 using neural stem cell (NSC) specific, inducible Cre mice crossed to IL-1R floxed mice. Next, we test the role of IL-1R1 signaling on recovery of the hippocampal trisynaptic cirucuit via NSC- specific or microglial-specific Cre-IL-1R1 floxed mice. Last, using the same mice as the previous experiment, we will perform behavioral tests on mice recovered from B.1.351 to examine the functional impact of IL-1R1 signaling. Together, in this proposal we will explore the immunological mechanisms that underlie neurological dysfunction during COVID-19.