Epigenetic regulation of sexually divergent neuroinflammation with brain aging and Alzheimer's disease

项目摘要/摘要 年龄和性别是发展为阿尔茨海默病(AD)的主要危险因素， 所有年龄段的女性，从60岁到100岁。导致阿尔茨海默病性别差异的潜在机制不是 很好地理解，防止制定针对性别的治疗干预措施。慢性的，低级的 炎症是大脑老化和神经退化的特征。作为中枢神经系统的前哨巨噬细胞， 小胶质细胞在感知和响应中枢神经系统环境的变化中起着重要作用。小胶质细胞监测 外源/“非我”和内源性物质的中枢神经系统，既服务于神经保护，也服务于神经退行性变 功能。在正常生理条件下，小胶质细胞保持相对静止、监视的表型； 然而，刺激可以使小胶质细胞分化为促炎M1表型或抗炎M2表型 表型。小胶质细胞表型转换的控制涉及DNA修饰的调节，主要是 胞嘧啶的甲基化和羟甲基化，控制基因组的可及性和基因表达。 女性小胶质细胞特异性炎症通路的活跃激活与年龄和性别差异 DNA随年龄的变化表明，在大脑老化和神经炎症的性别差异中，表观遗传学起到了作用。 然而，配对的表观基因组学和转录组学研究还没有在患有 性别之间的年龄。为了解决这一进展障碍，我们开发了小胶质细胞特异性的三苯氧胺诱导剂， 转基因NuTRAP模型允许从谱系追踪的小胶质细胞中分离核酸(DNA和RNA)。在……里面 目的1、MC/HMC小胶质细胞特异性海马区随增龄变化的全基因组研究 氧化亚硫酸氢盐测序(WGoxBS)。表观基因组数据，以及来自其的配对转录组数据 动物将被用来确定改变的修饰模式在与年龄相关的基因变化中的作用 表达，丰富基因组调节区的差异修饰，并鉴定基因组 为将来的表观基因组编辑实验提供基因座。尽管在目前的一些啮齿类动物中记录到了性分化 阿尔茨海默病模型，该领域公认的限制是转基因动物在 青年时期，不像零星的AD，发生在生命的晚期。新的AD模型，如淀粉样β蛋白(Aβ)寡聚体 输液允许在大脑老化和性别影响的背景下检查与AD相关的Aβ神经病理。在……里面 目的2，我们将β寡聚体输注与我们的新的NuTRAP模型相结合来选择性地分析小胶质细胞的特异性 Aβ神经毒性背景下的表观基因组和转录改变。此外，免疫组织化学和 细胞因子/趋化因子面板用于胶质细胞增生症的读数，以评估衰老对β诱导的小胶质细胞的影响 两性之间的反应性。如果成功，这些研究将为研究性别分化的小胶质细胞提供洞察力 功能与年龄和β相关的神经病理和确定性别特异性发展的靶点 治疗性干预。未来的研究也将利用这些发现来检验性行为的调节 与大脑老化有关的分歧。

PROJECT SUMMARY/ABSTRACT Age and sex are the primary risk factors for developing Alzheimer’s disease (AD), with a higher incidence in women at all ages from 60-100 years old. Mechanisms underlying the cause of sex differences in AD are not well understood, preventing the development of sex-specific therapeutic interventions. Chronic, low-grade inflammation is characteristic of brain aging and neurodegeneration. As the sentinel macrophages of the CNS, microglia play an important role in sensing and responding to changes in the CNS milieu. Microglia monitor the CNS for foreign/’non-self’ and endogenous substances, serving both neuroprotective and neurodegenerative functions. Under normal physiological conditions, microglia retain a relatively quiescent, surveillance phenotype; however stimulation can polarize microglia to the pro-inflammatory M1 phenotype or anti-inflammatory M2 phenotype. Control of microglial phenotypic switching involves regulation of DNA modifications, principally methylation and hydroxymethylation of cytosines, which control genome accessibility and gene expression. Exuberant activation of microglial-specific inflammatory pathways with age in females and sexual divergence in DNA modifications with age point to an epigenetic role in sex differences in brain aging and neuroinflammation. However, paired epigenomic and transcriptomic studies have not been conducted in hippocampal microglia with age between sexes. To address this barrier to progress we developed microglial-specific, tamoxifen-inducible, transgenic NuTRAP models to allow isolation of nucleic acids (DNA & RNA) from lineage-traced microglia. In Aim 1, microglial-specific hippocampal changes in mC/hmC with aging will be examined by whole genome oxidative bisulfite sequencing (WGoxBS). Epigenomic data, and the paired transcriptomic data from the same animals will be used to determine the role of altered modification patterns in age-related changes in gene expression, enrichment of differential modifications in regulatory regions of the genome, and to identify genomic loci for future epigenome editing experiments. Although sexual divergence is documented in some current rodent models of AD, an acknowledged limitation in the field is that transgenic animals develop AD neuropathology at a young age, unlike sporadic AD, which occurs late in life. New AD models like amyloid-beta (Aβ) oligomer infusion allow for examination of AD-related Aβ neuropathology in the context of brain aging and sex effects. In Aim 2, we combine Aβ-oligomer infusion with our novel NuTRAP model to selectively analyze microglial-specific epigenomic and transcriptomic changes in the context of Aβ neurotoxicity. Further, immunohistochemistry and cytokine/chemokine panels are used readouts for gliosis, to assess the effect of aging on Aβ-induced microglial reactivity between sexes. If successful, these studies will provide insights into sexually divergent microglial function with aging and Aβ-related neuropathology and identify targets for development of sex-specific therapeutic interventions. Future studies will also use these findings to examine the regulators of sexual divergence with brain aging.