Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne, UK.
Institute of Neuroscience and Psychology, University of Glasgow, Queen Elizabeth University Hospital, Glasgow, UK.
Brain Pathol. 2022 Nov;32(6):e13101. doi: 10.1111/bpa.13101. Epub 2022 Jun 24.
With the hypothesis that perivascular microglia are involved as neuroinflammatory components of the gliovascular unit contributing to white matter hyperintensities on MRI and pathophysiology, we assessed their status in stroke survivors who develop dementia. Immunohistochemical and immunofluorescent methods were used to assess the distribution and quantification of total and perivascular microglial cell densities in 68 brains focusing on the frontal lobe WM and overlying neocortex in post-stroke dementia (PSD), post-stroke non-dementia (PSND) and similar age control subjects. We primarily used CD68 as a marker of phagocytic microglia, as well as other markers of microglia including Iba-1 and TMEM119, and the myeloid cell marker TREM2 to assess dementia-specific changes. We first noted greater total densities of CD68 and TREM2 cells per mm in the frontal WM compared to the overlying cortex across the stroke cases and controls (p = 0.001). PSD subjects showed increased percentage of activated perivascular CD68 cells distinct from ramified or primed microglia in the WM (p < 0.05). However, there was no apparent change in perivascular TREM2 cells. Total densities of TREM2 cells were only ~10% of CD68 cells but there was high degree of overlap (>70%) between them in both the WM and the cortex. CD68 and Iba-1 or CD68 and TMEM119 markers were colocalised by ~55%. Within the deep WM, ~30% of CD68+ cells were co-localised with fragments of degraded myelin basic protein. Among fragmented CD68+ cells in adjacent WM of PSD subjects, >80% of the cells expressed cleaved caspase-3. Our observations suggest although the overall repertoire of perivascular microglial cells is not changed in the parenchyma, PSD subjects accrue more perivascular-activated CD68+ microglia rather than TREM2+ cells. This implies there is a subset of CD68+ cells, which are responsible for the differential response in perivascular inflammation within the gliovascular unit of the deep WM.
基于血管周围小胶质细胞是神经炎症成分的假说，它们是促成 MRI 上的脑白质高信号和病理生理学改变的脑血单元的一部分，我们评估了它们在发生痴呆的中风幸存者中的状态。我们使用免疫组织化学和免疫荧光方法评估了 68 例大脑中总小胶质细胞和血管周围小胶质细胞密度的分布和定量，重点关注中风后痴呆（PSD）、中风后非痴呆（PSND）和相似年龄对照组的额叶 WM 和覆盖的皮质。我们主要使用 CD68 作为吞噬性小胶质细胞的标志物，以及其他小胶质细胞标志物，包括 Iba-1 和 TMEM119，以及髓样细胞标志物 TREM2，以评估与痴呆相关的变化。我们首先注意到，与对照组相比，在所有中风病例中，额叶 WM 中 CD68 和 TREM2 细胞的密度每毫米更高（p=0.001）。与 PSD 患者的 WM 中激活的血管周围 CD68 细胞不同，它们与分枝或预激活的小胶质细胞不同（p<0.05）。然而，血管周围 TREM2 细胞没有明显变化。TREM2 细胞的总密度仅约为 CD68 细胞的 10%，但在 WM 和皮质中，它们之间有很高的重叠（>70%）。CD68 和 Iba-1 或 CD68 和 TMEM119 标志物的共定位约为 55%。在深部 WM 中，约 30%的 CD68+细胞与降解的髓鞘碱性蛋白片段共定位。在 PSD 患者相邻 WM 的碎片 CD68+细胞中，>80%的细胞表达 cleaved caspase-3。我们的观察表明，尽管在实质内血管周围小胶质细胞的总体谱没有改变，但 PSD 患者积累了更多的血管周围激活的 CD68+小胶质细胞，而不是 TREM2+细胞。这意味着存在一小部分 CD68+细胞，它们负责深部 WM 中脑血单元内血管周围炎症的差异反应。
