Exploring the role of microbiota and inflammation in tic fluctuations

摘要 慢性抽动障碍（CTD），包括图雷特氏症和持续性抽动障碍，是一种重要的神经系统疾病。 儿童和青少年残疾的主要原因，但药物治疗仍然非常不令人满意 由于严重的不良事件。开发更安全的CTD治疗方法的理想方向是靶向 相同的生物过程，抽搐自发地蜡和减弱随着时间的推移，然而，机制 对这些波动的根本原因仍知之甚少。 一个新的机会来解决这个问题可能来自最近的证据表明，抽搐的严重程度是 受到肠道菌群的影响。了解肠道微生物群组成的变化 可能解释抽搐恶化-并通过分子机制-可能导致治疗 CTD方面的突破;然而，这一问题仍未得到探讨。本R21建议的研究目标 应用的目的是探索肠道微生物群的变化是否以及如何导致抽搐恶化。 肠道微生物群可能通过多种机制影响抽搐的严重程度，包括合成 炎性细胞因子大量相关证据表明，肿瘤坏死因子-α（TNF）是 炎性细胞因子与抽搐恶化最相关。因此，为了测试这种细胞因子是否会增加抽搐， 严重性，我们评估了其在CTD小鼠模型中的作用。这些初步研究表明，低TNF 不引起病态行为的剂量显著增加这些小鼠中的抽搐样刻板行为。 基于这些发现，我们假设，在CTD患者中，肠道微生物群的改变导致 TNF或其他炎性细胞因子的产生，从而加剧抽搐。为了验证这一假设， 本R21申请中提出的探索性研究将使用转化平台，结合临床 在CTD患者中的分析和在小鼠模型中的机理实验。具体而言： - 在目标1中，我们将评估与CTD相关的肠道微生物群的改变，并测试抽搐是否 急性加重与肠道微生物群和炎症反应的改变有关， 来自40名CTD患者和40名未受影响的对照的粪便和血液样品。 - 在目标2中，我们将通过以下方式测试肠道微生物群改变与抽搐加重之间的因果关系： 将CTD患者的粪便样本移植到我们的抽动秽语障碍小鼠模型中; 我们还将检测TNF或其他炎性细胞因子是否对抽动严重程度的潜在变化有贡献。 在这项R21申请中提出的转化研究将是第一个系统分析肠道作用的研究。 微生物群的波动。如果我们的假设得到证实，未来的R01资助的研究将测试粪便是否 从未受影响的个体移植物质和/或益生菌治疗可以降低抽搐的严重程度。我们将 也研究炎症增加抽搐严重性的下游机制。因此，我们的结果可能 导致开发新的，更安全的，基于机制的CTD治疗方法。

ABSTRACT Chronic tic disorders (CTD), including Tourette’s disorder and persistent tic disorders, are a significant source of disability for children and adolescents, yet pharmacological therapies remain highly unsatisfactory due to serious adverse events. An ideal direction to develop safer treatments for CTD would be to target the same biological processes whereby tics spontaneously wax and wane over time; however, the mechanisms underlying these fluctuations remain poorly understood. A novel opportunity to solve this problem may come from recent evidence documenting that tic severity is influenced by the gut microbiota. Understanding whether changes in the composition of the gut microbiota may account for tic exacerbations - and through which molecular mechanisms - may lead to therapeutic breakthroughs in CTD; this issue, however, remains unexplored. The goal of the studies proposed in this R21 application is to explore whether and how variations in the gut microbiota contribute to tic exacerbations. The gut microbiota may influence tic severity through multiple mechanisms, including the synthesis of inflammatory cytokines. Ample correlational evidence points to tumor necrosis factor-α (TNF) as the inflammatory cytokine best associated with tic exacerbations. Thus, to test whether this cytokine increases tic severity, we evaluated its effects in a mouse model of CTD. These preliminary studies showed that low TNF doses that do not elicit sickness behavior significantly increase tic-like stereotypies in these mice. Based on these findings, we hypothesize that, in CTD patients, gut microbiota alterations lead to increased production of TNF or other inflammatory cytokines, which exacerbate tics. To test this hypothesis, the exploratory studies proposed in this R21 application will use a translational platform, combining clinical analyses in CTD patients and mechanistic experiments in mouse models. Specifically: - In Aim 1, we will assess the alterations of gut microbiota associated with CTD and test whether tic exacerbations are associated with alterations of the gut microbiota and inflammatory responses by testing fecal and blood samples from forty CTD patients and forty non-affected controls. - In Aim 2, we will test the causal link between gut microbiota alterations and tic exacerbations by transplanting fecal specimens from CTD-affected individuals into our mouse models of Tourette’s disorder; we will also test whether TNF or other inflammatory cytokines contribute to potential changes in tic severity. The translational studies proposed in this R21 application will be the first systematic analyses of the role of gut microbiota in tic fluctuations. If our hypothesis is verified, future R01-funded studies will test whether fecal material transplant from non-affected individuals and/or probiotic treatments can reduce tic severity. We will also study the downstream mechanisms whereby inflammation increases tic severity. Thus, our results may lead to the development of new, safer, mechanistically based treatments for CTD.