Inflammation-Induced Behavioral Alterations: A Psychogenomic Approach

描述(申请人提供)：重度抑郁症是发达国家第二大疾病负担，也是导致残疾的主要原因。炎症在抑郁症中的作用已经确定，然而，要更完整地了解与炎症诱导的抑郁症相关的分子机制和生物过程，需要对个别候选系统的可能性进行调查。这项应用的基本原理是通过对炎症诱导的抑郁机制进行全基因组功能分析和网络重建来填补目前存在的空白。我们将结合我们经过验证和接受的卡介苗(BCG)诱导的炎症小鼠模型和我们的吲哚胺2，3双加氧酶基因敲除(IDO KO)小鼠来回答两个重要的限速问题：目的1)在BCG诱导的抑郁症中，哪些基因在先天免疫细胞中有差异表达？目的2)卡介苗诱导的抑郁基因的生物学功能和网络是什么？目标1将通过使用RNA-Seq测量的先天性免疫细胞的转录组特征来实现。我们已经证明了这项提议的三个关键基石。首先，接种卡介苗会导致持续至少3周的类似抑郁的长期行为。其次，卡介苗诱导的抑郁是由IDO激活介导的，IDO KO小鼠与野生型小鼠一样发展为炎症，尽管它们没有表现出类似抑郁的行为。第三，肺和脑巨噬细胞在增强炎症行为反应中起着至关重要的作用。因此，将使用随机2x2析因设计，包括两个处理(BCG-挑战和生理盐水对照)和两个小鼠品系(野生型和IDO KO)。根据能量分析，每个攻击品系组12只小鼠的肺巨噬细胞和脑小胶质细胞将在攻击后2周采集。不同组之间的消减和差异表达对比将允许识别炎症诱导的抑郁基因，这些基因在抑郁症样行为的长期模型中表达，并且：1)独立于可能有助于康复的炎症和免疫变化，2)独立于基线菌株差异。目标2将通过对目标1中确定的基因进行抽象主义功能分析和基因网络重建来解决。除了知识发现，我们还将测试有关抑郁症功能特征的具体假设，包括：5-羟色胺、鸟嘌呤-四氢生物蝶呤、一氧化氮、能量代谢途径和转录因子。关键转录本将使用实时定量聚合酶链式反应进行确认。一个拥有神经科学、行为学、免疫学、转录组分析和生物信息学专业知识的多学科团队已经组成，以完成拟议的研究。这项申请提交给R21计划是因为提出了一项有针对性的RNA-Seq“探索性实验”，并对途径和网络进行了创新性的比较。拟议的研究成果包括：1)确定炎症导致抑郁的分子机制，包括免疫途径和调控基序；2)阐明炎症与抑郁之间的关系；3)深入了解相关过程，如年龄依赖的炎症诱导的抑郁和其他与炎症相关的神经疾病，包括焦虑、自闭症、精神分裂症、阿尔茨海默病和人类免疫缺陷病毒引起的痴呆症，以及对酒精和药物的依赖。 公共卫生相关性：我们已经从汇集的临床和实验数据中了解到，抑郁症是在炎症条件下的疾病背景下发展起来的。对炎症诱导的抑郁的分子基础的全面理解将产生于第一个系统生物学方法，即使用功能分析和基因网络重建来研究转录组的特征。这项研究在知识发现和假设生成方面的结果将有助于开发预测和诊断工具，从而为那些受到炎症诱导的行为障碍困扰的人提供预防和补救治疗。

DESCRIPTION (provided by applicant): Major depression is the second largest burden of disease in the developed world and a leading cause of disability. The role of inflammation in depression has been established, yet a more complete understanding of the molecular mechanisms and biological processes associated with inflammation-induced depression requires an investigation of possibilities that lie "outside the box" of individual candidate systems. The rationale of this application is to fill the void that currently exists through a genome-wide functional analysis and network reconstruction of the mechanisms of inflammation-induced depression. We will integrate our well-validated and accepted murine model of Bacillus Calmette-Guerin (BCG) induced inflammation and our indoleamine 2,3 dioxygenase knock-out (IDO KO) mice to answer two important and rate-limiting questions: Aim 1) What genes are differentially expressed in innate immune cells in BCG-induced depression? Aim 2) What are the biological functions and networks of the BCG-induced depression genes? Aim 1 will be addressed by characterizing the transcriptome profile of innate immune cells measured using RNA-Seq. We have demonstrated the three pivotal cornerstones for this proposal. First, BCG inoculation induces long-lasting depression-like behaviors that persist for at least 3 weeks. Second, BCG-induced depression is mediated by IDO activation and IDO KO mice develop inflammation just as wild-type mice, although they do not display depression-like behaviors. Third, lung and brain macrophages play a crucial role in mounting inflammatory behavioral response. Therefore, a randomized 2x2 factorial design including two treatments (BCG-challenge and saline control) and two mice strains (wild type and IDO KO) will be used. Lung macrophages and brain microglia from 12 mice per challenge-strain group, based on power analysis, will be collected 2 weeks after challenge. Subtractive and differential expression contrasts between groups will permit identification of inflammation-induced depression genes that are expressed in a long-lasting model of depression-like behavior and: 1) are independent of changes in inflammation and immunity that may contribute to recovery, and 2) are independent of baseline strain differences. Aim 2 will be addressed using abstractionist functional analyses of the genes identified in Aim 1 and gene network reconstruction. In addition to knowledge discovery, we will test concrete hypotheses on the functional signature of depression, including: serotonin, guanine-tetrahydrobiopterin nitric oxide, and energy metabolism pathways and transcription factors. Key transcripts will be confirmed using Real Time Quantitative PCR. A multidisciplinary team with expertise in neuroscience, behavior, immunity, transcriptome analysis and bioinformatics has been assembled to accomplish the proposed research. This application is submitted to the R21 program because a targeted RNA-Seq "exploratory experiment" and innovative comparison of pathways and networks are proposed. The outcomes of the proposed research are: 1) identification of molecular mechanisms including immune pathways and regulatory motifs that underlie inflammation-induced depression, 2) elucidation of the relationship between inflammation and depression, and 3) insights on related processes such as age-dependent inflammation-induced depression and other inflammation-associated neurological disorders, including anxiety, autism, schizophrenia, Alzheimer's disease and dementia caused by human immunodeficiency virus, and addictions to alcohol and drugs. PUBLIC HEALTH RELEVANCE: We already know from converging clinical and experimental data that depression develops on a background of sickness under conditions of inflammation. A comprehensive understanding of the molecular basis of inflammation-induced depression will result from this first systems biology approach to investigate the transcriptome profile using functional analysis followed by gene network reconstruction. The outcomes of this study in terms of knowledge discovery and hypothesis generation will help to develop prognostic and diagnostic tools that will lead to preventive and remedial treatments for those afflicted by inflammation-induced behavioral disorders.