Fecal Microbiota Transfer Attenuates Aged Gut Dysbiosis and Functional Deficits after Traumatic Brain Injury

项目摘要/摘要 创伤性脑损伤(TBI)每年困扰着大约300万美国人。最高的 脑损伤的发病率发生在75岁及以上的成年人中，他们的死亡率较高，长期脑损伤较严重。 足月功能结果比年轻人更好。这种与年龄相关的结局差异也 在各种动物研究中都有报道。然而，分子和细胞机制只有 已经部分阐明，而明显缺乏针对年龄的脑损伤治疗。我们出版的 微生物组分析(16S RNA基因测序)数据显示，老龄小鼠在脑损伤后 显示有益的共生肠道细菌的损失更大，机会主义的上升更高 与年轻的成年脑损伤小鼠相比，这是一种有害物种。这种肠道代谢失调的增加 与老年脑外伤小鼠更严重的神经退行性变和神经认知缺陷有关。值得注意的是 初步数据显示，撞击损伤的大小显著减小，衰减 通过粪便将健康微生物群转移到幼年脑损伤小鼠的神经认知障碍 微生物组移植(FMT)因此，戴维斯博士假设脑外伤后的放置 将年轻的微生物群植入老年小鼠将减轻神经退行性变和神经认知 赤字。对于提议的研究的K99阶段，戴维斯博士将通过单一的 细胞RNA测序(scRNA-seq)以询问小胶质细胞在 老年小鼠脑损伤后FMT治疗后的损伤过程。他还将比较微生物组的scRNA-seq 用定量核磁共振测量解剖、神经认知和病理结果的数据， 行为表型和组织病理学。对于拟议研究的R00阶段，Dr。 Davis将利用SCFA重组的老年(80周大)无菌(GF)C57BL/6小鼠- 在颅脑损伤或假损伤前产生细菌丁状弧菌(B.fib)。突变的B.fib 生产的SCFA将减少10倍，将被用作对照。另一群年迈的野生型 C57BL/6小鼠将接受含有SCFAs(丁酸盐、醋酸盐和丙酸)的水与赋形剂 在TBI之后。ScRNAseq将用于确定目标微生物替代或SCFA饮食 补充剂可以减弱小胶质细胞的激活。解剖学、神经认知学和病理学 结果指标将通过MRI、行为表型和组织病理学来确定。 综上所述，这项建议将通过为以下方面提供新的见解来填补目前老年脑损伤研究的空白 导致与衰老相关的不同脑损伤预后的分子和细胞机制， 反过来，它可以精确定位潜在的针对衰老的脑损伤治疗靶点，这些靶点严重 缺乏。

Project Summary/Abstract Traumatic brain injury (TBI) afflicts about three million Americans every year. The highest incidence of TBI occurs in adults aged 75 and older who have higher mortality and worse long- term functional outcomes than younger adults. This age-associated outcome difference has also been reported in various animal studies. Yet, the molecular and cellular mechanisms have only been partially elucidated, and age specific TBI treatments are notably lacking. Our published microbiome analysis (16S RNA gene sequencing) data revealed that aged mice post-TBI demonstrate a greater loss of beneficial commensal gut bacteria and a higher rise in opportunistic deleterious species in the compared to young adult TBI mice. This increase in gut dysbiosis correlated with worse neurodegeneration and neurocognitive deficits in aged TBI mice. Of note preliminary data reveals a significant decrease in the size of the impact lesion and an attenuation of neurocognitive deficits with transfer of a healthy microbiome into young adult TBI mice via fecal microbiome transplantations (FMT) Hence, Dr. Davis hypothesizes that the post-TBI placement of a young microbiome into an aged mouse will attenuate neurodegeneration and neurocognitive deficits. For the K99 phase of the proposed research, Dr. Davis will validate the findings via single cell RNA sequencing (scRNA-seq) to interrogate the transcriptional profiles of microglia over the course of injury in aged mice FMT treated post-TBI. He will also compare microbiome scRNA-seq data to anatomic, neurocognitive, and pathologic outcome measures with quantitative MRI, behavioral phenotyping, and histopathology. For the R00 phase of the proposed research, Dr. Davis will utilize aged (80-weeks-old) germ-free (GF) C57BL/6 mice reconstituted with the SCFA- producing bacterium Butyrivibrio fibrosolvens (B. fib) before TBI or sham injury. Mutant B.fib that produces 10-fold less SCFA will be used as a control. A separate cohort of aged wild type C57BL/6 mice will receive water containing SCFAs (butyrate, acetate, and propionate) vs. vehicle after TBI. scRNAseq will be used to determine if targeted microbial replacement or SCFA dietary supplementation can attenuate microglia activation. Anatomic, neurocognitive, and pathologic outcome measures will be determined with MRI, behavioral phenotyping, and histopathology. Together, this proposal will fill current gaps in geriatric TBI research by providing new insights into the molecular and cellular mechanisms leading to aging-associated differential TBI outcomes, which can, in turn, pinpoint potential aging-specific TBI therapeutic targets, which are severely lacking.