Exploring the role of microbiota and inflammation in tic fluctuations

摘要 慢性抽动障碍(CTD)，包括抽动障碍和持续性抽动障碍，是一种重要的 儿童和青少年的残疾来源，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针对 相同的生物过程，抽搐会随着时间的推移自发地消退；然而，其机制 人们对这些波动背后的原因仍然知之甚少。 一个解决这个问题的新机会可能来自最近的证据，证明抽搐的严重性是 受肠道微生物区系的影响。了解肠道微生物区系的组成是否发生变化 可能是抽动加剧的原因--以及通过哪些分子机制--可能导致治疗 CTD方面的突破；然而，这一问题仍未得到探索。本R21中提出的研究目标 应用是探索肠道微生物区系的变化是否以及如何导致抽动加剧。 肠道微生物区系可能通过多种机制影响抽动的严重性，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是 炎性细胞因子最好与抽搐加重有关。因此，为了测试这种细胞因子是否会增加抽动 严重程度，我们在CTD小鼠模型上评估了它的效果。这些初步研究表明，低肿瘤坏死因子 不会引起疾病行为的剂量显著增加了这些小鼠的抽搐样刻板印象。 基于这些发现，我们假设，在CTD患者中，肠道微生物区系的改变导致 产生肿瘤坏死因子或其他炎性细胞因子，加剧抽搐。为了检验这一假设， 在此R21应用中提出的探索性研究将使用翻译平台，结合临床 CTD患者的分析和小鼠模型的力学实验。具体地说，就是： -在目标1中，我们将评估与CTD相关的肠道微生物区系的变化，并测试是否抽搐 通过测试，病情恶化与肠道微生物区系和炎症反应的改变有关 来自40名CTD患者和40名正常对照的粪便和血液样本。 -在目标2中，我们将通过以下方式测试肠道微生物区系变化和抽动加剧之间的因果联系 将CTD患者的粪便样本移植到我们的抽动症小鼠模型中； 我们还将测试肿瘤坏死因子或其他炎性细胞因子是否有助于抽搐严重程度的潜在变化。 在这项R21应用中提出的翻译研究将是第一次系统地分析肠道的作用 TIC波动中的微生物区系。如果我们的假设得到证实，未来由R01资助的研究将测试粪便 从未受影响的个人进行材料移植和/或益生菌治疗可以减轻抽动的严重程度。我们会 也要研究炎症增加抽动严重程度的下游机制。因此，我们的结果可能 导致开发新的、更安全的、基于机械的治疗CTD的方法。

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.