Department of Anatomy and Medical Imaging, Faculty of Medical and Health Science, University of Auckland, Private Bag 92019, Auckland, New Zealand.
Centre for Brain Research, Faculty of Medical and Health Science, University of Auckland, Private Bag 92019, Auckland, New Zealand.
Acta Neuropathol Commun. 2020 Oct 20;8(1):170. doi: 10.1186/s40478-020-01047-9.
In Alzheimer's disease (AD), microglia are affected by disease processes, but may also drive pathogenesis. AD pathology-associated microglial populations have been identified with single-cell RNA-Seq, but have not been validated in human brain tissue with anatomical context. Here, we quantified myeloid cell markers to identify changes in AD pathology-associated microglial populations. We performed fluorescent immunohistochemistry on normal (n = 8) and AD (n = 8) middle temporal gyri, co-labelling the pan-myeloid cell marker, Iba1, with one of 11 markers of interest (MOIs): CD45, HLA-DR, CD14, CD74, CD33, CD206, CD32, CD163, P2RY12, TMEM119, L-Ferritin. Novel image analyses quantified the single-cell abundance of Iba1 and each MOI. Each cell was gated into one Iba1-MOI population (Iba1 MOI, Iba1 MOI, or Iba1 MOI) and the abundance of each population was compared between AD and control. Triple-labelling of L-Ferritin and Iba1 with a subset of MOIs was performed to investigate L-Ferritin-MOI co-expression on Iba1 cells. Iba1 MOI myeloid cell populations delineated by MOIs CD45, HLA-DR, CD14, CD74, CD33, CD32, and L-Ferritin were increased in AD. Further investigation of the Iba1 MOI populations revealed that their abundances correlated with tau, but not amyloid beta, load in AD. The Iba1 microglial population highly expressed L-Ferritin, reflecting microglial dysfunction. The L-Ferritin CD74 HLA-DR phenotype of the Iba1 population mirrors that of a human AD pathology-associated microglial subpopulation previously identified using single-cell RNA-Seq. Our high-throughput immunohistochemical data with anatomical context support the microglial dysfunction hypothesis of AD.
在阿尔茨海默病（AD）中，小胶质细胞受到疾病过程的影响，但也可能驱动发病机制。利用单细胞 RNA-Seq 已经鉴定出与 AD 病理相关的小胶质细胞群体，但尚未在具有解剖学背景的人类脑组织中进行验证。在这里，我们量化了髓样细胞标志物，以确定与 AD 病理相关的小胶质细胞群体的变化。我们对正常（n=8）和 AD（n=8）颞中回进行了荧光免疫组织化学染色，用 pan-myeloid 细胞标志物 Iba1 与 11 个感兴趣的标志物（MOI）之一进行共标记：CD45、HLA-DR、CD14、CD74、CD33、CD206、CD32、CD163、P2RY12、TMEM119、L-铁蛋白。新的图像分析定量了 Iba1 和每个 MOI 的单细胞丰度。每个细胞都被门控到一个 Iba1-MOI 群体（Iba1 MOI、Iba1 MOI 或 Iba1 MOI），并比较了 AD 和对照组之间每个群体的丰度。对 L-铁蛋白和 Iba1 进行了一组 MOIs 的三重标记，以研究 Iba1 细胞上 L-铁蛋白-MOI 的共表达。用 MOIs CD45、HLA-DR、CD14、CD74、CD33、CD32 和 L-铁蛋白划分的 Iba1 MOI 髓样细胞群体在 AD 中增加。对 Iba1 MOI 群体的进一步研究表明，它们的丰度与 AD 中的 tau 相关，而与淀粉样蛋白β无关。Iba1 小胶质细胞群体高度表达 L-铁蛋白，反映了小胶质细胞功能障碍。Iba1 群体的 L-铁蛋白 CD74 HLA-DR 表型反映了先前使用单细胞 RNA-Seq 鉴定的人类 AD 病理相关小胶质细胞亚群的表型。我们具有解剖学背景的高通量免疫组织化学数据支持 AD 中小胶质细胞功能障碍的假说。
