背景:高同型半胱氨酸血症(HHcy)与阿尔茨海默病(AD)的发展有关,其神经病理学特征是淀粉样蛋白β(Aβ)的积累。小胶质细胞(MG)在Aβ原纤维的摄取中起着至关重要的作用,其功能障碍会使AD恶化。然而,HHcy对MGAβ吞噬的影响仍未研究。
方法:我们从患有遗传性胱硫醚-β-合酶缺陷(Cbs-/-)的HHcy小鼠的大脑中分离出MG,并进行了大量RNA-seq。我们对Cbs-/-小鼠MG的转录组进行了荟萃分析,人类和小鼠ADMG,MGAβ吞噬模型,人类AD甲基化组,和GWASAD基因。
结果:在Cbs-/-小鼠中鉴定了HHcy和低甲基化状况。通过Cbs-/-MG转录组分析,鉴定出353个MGDEGs。在Cbs-/-MG中发现吞噬体形成和整合素信号通路被抑制。通过分析4例AD患者和7例小鼠AD数据集的MG转录组,确定了409个人和777只小鼠ADMGDEGs,其中37个在两个物种中都很常见。通过进一步结合MGAβ吞噬模型的转录组分析,我们确定了130个功能验证的Aβ吞噬ADMGDEGs(人类AD中20个,110inmouseAD),这反映了Aβ吞噬作用的代偿激活。有趣的是,我们确定了14个人Aβ吞噬ADMGDEGs,它们代表了人AD中MGAβ吞噬功能受损。最后,通过一系列ADMG转录组的荟萃分析,功能性吞噬作用,HHcyMG,和人类AD脑甲基化组数据集,我们确定了5种HHcy抑制的吞噬细胞ADMGDEGs(Flt1,Calponin3,Igf1,Cacna2d4和Celsr),据报道它们可以调节MG/MΦ的迁移和Aβ的吞噬作用。
结论:我们建立了人和小鼠ADMG中Aβ吞噬作用激活和人ADMG中Aβ吞噬作用受损的代偿反应的分子特征。我们的发现表明,低甲基化可能会调节AD中HHcy抑制的MGAβ吞噬作用。
Hyperhomocysteinemia (HHcy) has been linked to development of Alzheimer\'s disease (AD) neuropathologically characterized by the accumulation of amyloid β (Aβ). Microglia (MG) play a crucial role in uptake of Aβ fibrils, and its dysfunction worsens AD. However, the effect of HHcy on MG Aβ phagocytosis remains unstudied.
We isolated MG from the cerebrum of HHcy mice with genetic cystathionine-β-synthase deficiency (Cbs-/-) and performed bulk RNA-seq. We performed meta-analysis over transcriptomes of Cbs-/- mouse MG, human and mouse AD MG, MG Aβ phagocytosis model, human AD methylome, and GWAS AD genes.
HHcy and
hypomethylation conditions were identified in Cbs-/- mice. Through Cbs-/- MG transcriptome analysis, 353 MG DEGs were identified. Phagosome formation and integrin signaling pathways were found suppressed in Cbs-/- MG. By analyzing MG transcriptomes from 4 AD patient and 7 mouse AD datasets, 409 human and 777 mouse AD MG DEGs were identified, of which 37 were found common in both species. Through further combinatory analysis with transcriptome from MG Aβ phagocytosis model, we identified 130 functional-validated Aβ phagocytic AD MG DEGs (20 in human AD, 110 in mouse AD), which reflected a compensatory activation of Aβ phagocytosis. Interestingly, we identified 14 human Aβ phagocytic AD MG DEGs which represented impaired MG Aβ phagocytosis in human AD. Finally, through a cascade of meta-analysis of transcriptome of AD MG, functional phagocytosis, HHcy MG, and human AD brain methylome dataset, we identified 5 HHcy-suppressed phagocytic AD MG DEGs (Flt1, Calponin 3, Igf1, Cacna2d4, and Celsr) which were reported to regulate MG/MΦ migration and Aβ phagocytosis.
We established molecular signatures for a compensatory response of Aβ phagocytosis activation in human and mouse AD MG and impaired Aβ phagocytosis in human AD MG. Our discoveries suggested that
hypomethylation may modulate HHcy-suppressed MG Aβ phagocytosis in AD.