Sheffield Institute for Translational Neuroscience, University of Sheffield, 385a Glossop Road, Sheffield, S10 2HQ, UK.
Population Health Sciences Institute, Newcastle University, Newcastle upon Tyne, UK.
Acta Neuropathol Commun. 2021 Jan 6;9(1):5. doi: 10.1186/s40478-020-01109-y.
Type 2 diabetes mellitus (T2D), characterised by peripheral insulin resistance, is a risk factor for dementia. In addition to its contribution to small and large vessel disease, T2D may directly damage cells of the brain neurovascular unit. In this study, we investigated the transcriptomic changes in cortical neurones, and associated astrocytes and endothelial cells of the neurovascular unit, in the ageing brain. Neurone, astrocyte, and endothelial cell-enriched mRNA, obtained by immuno-laser capture microdissection of temporal cortex (Brodmann area 21/22) from 6 cases with self-reported T2D in the Cognitive Function and Ageing Study neuropathology cohort, and an equal number of age and sex-matched controls, was assessed by microarray analysis. Integrated Molecular Pathway Level Analysis was performed using the Kyoto Encyclopaedia of Genes and Genomes database on significantly differentially expressed genes, defined as P < 0.05 and fold-change ± 1.2. Hub genes identified from Weighted Gene Co-expression Network Analysis were validated in neurones using the NanoString nCounter platform. The expression and cellular localisation of proteins encoded by selected candidate genes were confirmed by immunohistochemistry. 912, 2202, and 1227 genes were significantly differentially expressed between cases with self-reported T2D and controls in neurones, astrocytes, and endothelial cells respectively. Changes in cortical neurones included alterations in insulin and other signalling pathways, cell cycle, cellular senescence, inflammatory mediators, and components of the mitochondrial respiratory electron transport chain. Impaired insulin signalling was shared by neurovascular unit cells with, additionally, apoptotic pathway changes in astrocytes and dysregulation of advanced glycation end-product signalling in endothelial cells. Transcriptomic analysis identified changes in key cellular pathways associated with T2D that may contribute to neuronal damage and dysfunction. These effects on brain cells potentially contribute to a diabetic dementia, and may provide novel approaches for therapeutic intervention.
2 型糖尿病（T2D）的特点是外周胰岛素抵抗，是痴呆的危险因素。除了对小血管和大血管疾病的贡献外，T2D 还可能直接损害脑神经血管单元的细胞。在这项研究中，我们研究了衰老大脑中皮质神经元以及神经血管单元中的相关星形胶质细胞和内皮细胞的转录组变化。通过免疫激光捕获微解剖来自认知功能和衰老研究神经病理学队列中自我报告患有 T2D 的 6 例患者（Brodmann 区域 21/22）的颞叶皮质获得神经元、星形胶质细胞和内皮细胞丰富的 mRNA，并与年龄和性别匹配的对照组进行了微阵列分析。使用京都基因和基因组百科全书数据库对显著差异表达基因进行了整合分子途径水平分析，定义为 P<0.05 和 fold-change±1.2。从加权基因共表达网络分析中确定的枢纽基因在神经元中使用 NanoString nCounter 平台进行了验证。通过免疫组织化学法证实了选定候选基因编码蛋白的表达和细胞定位。在神经元、星形胶质细胞和内皮细胞中，自我报告患有 T2D 的病例与对照组之间分别有 912、2202 和 1227 个基因的表达显著不同。皮质神经元的变化包括胰岛素和其他信号通路、细胞周期、细胞衰老、炎症介质以及线粒体呼吸电子传递链的组成部分的改变。神经血管单元细胞的胰岛素信号受损，此外，星形胶质细胞中凋亡途径的改变和内皮细胞中晚期糖基化终产物信号的失调。转录组分析确定了与 T2D 相关的关键细胞途径的变化，这些变化可能导致神经元损伤和功能障碍。这些对脑细胞的影响可能导致糖尿病性痴呆，并为治疗干预提供新的方法。
