Genetic Dissection of a VIP Link between Immune Dysfunction and Neurodevelopmental Disorders Characterized by Social Deficits

项目1项目摘要/摘要 免疫功能障碍在文献中被广泛报道为导致 以社交缺陷为特征的神经发育障碍，例如自闭症谱系障碍(ASD)和 精神分裂症。从进化论的角度来看，数百万年来，人类的行为，特别是 社会性是由两种古老的战斗力量塑造的：病原体和免疫系统。疾病行为 或者在ASD中避免社交，因此可以被视为大脑的一种免疫输入，以逃避 病原体的传播。过去十年内的新兴研究开始揭示免疫输入(例如， 脑膜免疫)确实会影响神经回路。关键问题仍然没有得到回答，包括是否， 免疫功能失调何时以及如何导致以社交为特征的神经发育障碍 赤字？此外，免疫系统能否在治疗上有针对性地改善中国的社会症状 自闭症和精神分裂症？最近，几项大规模的全基因组关联研究(GWAS)准确地指出 染色体7q36.6位点的拷贝数变异(CNV)在精神分裂症中高度存在 和自闭症，所有的微复制(三重)都发生在一个基因内：血管活性肠道 多肽受体2(VIPR2)。重要的是，VIPR2的配体、血管活性肠肽(VIP)几乎已被发现 使自闭症儿童新生儿血液中的正常水平增加了两倍。众所周知，VIP/VIPR2 信号调节免疫，使Th1/Th2平衡向Th2细胞倾斜。所有这些基因发现 找出长期寻找的社会缺陷和免疫功能失调之间的联系 神经发育障碍。将这种遗传脆弱性转化为机械性和病理生理学 有识之士，我们研制了一系列条件性VIPR2细菌人工染色体(BAC)转基因 VIPR2 CNV小鼠模型。BAC的条件设计允许在需要的情况下关闭转基因 由Cre重组酶控制的时空模式，从而促进了对受影响细胞的解剖 人口。基因过度激活的VIPR2信号导致出生后早期小胶质细胞修剪缺陷和 表现出强烈的社会赤字。因此，我们提出了VIP/VIPR2过度激活的中心假说 T细胞中的信号引发异常的免疫转化，扰乱社会性大脑发育和/或社会性 行为。这一假设将在以下具体目标中进行检验：目标1将检验潜在的 T细胞VIPR2 CNV在诱导全身性免疫失衡中的致病作用 发展。这个目标代表了第一个使用设计受体的化学遗传学方法。 由设计药物(DREADD)独家激活，与CREB-荧光素酶报告基因一起转基因 远程控制T细胞类型特异性GαS gpr/pKA信号，以确定VIPR2是否驱动Th2型 优先分化足以导致社会缺陷和大脑发育缺陷。我们的建议 病因学相关动物模型中的遗传询问将通过提供 第一次明确的因果证据表明，免疫功能失调是充分和必要的 大脑发育和/或表现出社会行为缺陷。鉴于目前还没有治疗疾病的疗法 对于自闭症和精神分裂症，我们的结果将产生重要的积极影响，因为它们奠定了基础 对于针对T细胞免疫的量身定制治疗(例如，小分子VIPR2拮抗剂)的想法 社会症状的解决，这是高度创新的，具有巨大的翻译价值。

Project 1 Project Summary/Abstract Immune dysfunction has been extensively reported in the literature as a risk factor contributing to neurodevelopmental disorders characterized by social deficits, e.g., autism spectrum disorder (ASD) and schizophrenia. From an evolutionary perspective, for many millions of years, human behavior, especially sociality, has been shaped by two ancient battling forces: pathogens and the immune system. Sickness behavior or avoidance of social interaction in ASD could thus be viewed as an immune input into the brain to evade the spreading of the pathogens. Emerging research within the last decade starts to reveal that immune inputs (e.g., meningeal immunity) can indeed affect neural circuits. The critical questions remain unanswered include whether, when and how a dysfunctional immunity can cause neurodevelopmental disorders characterized by social deficits? Besides, whether the immune system can be therapeutically targeted to ameliorate social symptoms in autism and schizophrenia? Recently, several large-scale genome-wide association studies (GWAS) pinpointed a Copy Number Variation (CNV) at the chromosomal locus 7q36.6 that is highly represented in schizophrenia and autism, with all of the microduplications (triplications) occurring within a single gene: vasoactive intestinal peptide receptor 2 (VIPR2). Importantly, VIPR2 ligand, vasoactive intestinal peptide (VIP) has been found almost tripled the normal level in the neonatal blood of children with autism. It has been well established that VIP/VIPR2 signaling modulates immunity and shifts the Th1/Th2 balance in favor of Th2 cells. All these genetic findings pinpoint a long-sought link between the social deficits and dysfunctional immunity consistently observed in neurodevelopmental disorders. To translate such a genetic vulnerability into a mechanistic and pathophysiologic insight, we have developed a series of conditional VIPR2 Bacterial Artificial Chromosome (BAC) transgenic mouse models of VIPR2 CNV. The conditional design of the BAC allows switching-off the transgene in desired spatial-temporal patterns, controlled by Cre recombinase, thus facilitating dissection of the inflicted cell populations. Genetically over-activated VIPR2 signaling elicits early postnatal microglial pruning deficits and manifests robust social deficits. Therefore, we propose the central hypothesis that over-activated VIP/VIPR2 signaling in T cells elicits abnormal immune transformation to disrupt social brain development and/or social behavior. The hypothesis will be examined in the following specific aims: Aim 1 will examine the potential pathogenic role of VIPR2 CNV in T cells to elicit systemic immune imbalance to disrupt early postnatal brain development. This aim represents the first to employ a chemogenetic approach with Designer Receptors Exclusively Activated by Designer Drugs (DREADD) together with CREB-luciferase reporter transgenesis to remotely control T cell-type-specific Gαs GPCR/PKA signaling to determine whether VIPR2 driven Th2 preferential differentiation is sufficient to elicit social deficits and brain developmental deficits. Our proposed genetic interrogation in an etiology-relevant animal model will shift the paradigm of the field by providing for the first time unequivocal causal evidence to that a dysfunctional immunity is sufficient and necessary to disrupt brain development and/or to manifest social behavioral deficits. Given that there is no disease-modifying therapy for autism and schizophrenia, our results will have an important positive impact because they lay the groundwork to the idea of tailoring of treatments (e.g., small molecule VIPR2 antagonist) targeting T cell immunity for resolution of social symptoms, which is highly innovative, and with tremendous translational value.