Comprehensive gene expression meta-analysis identifies signature genes that distinguish microglia from peripheral monocytes/macrophages in health and glioma

Abstract

Monocytes/macrophages have begun to emerge as key cellular modulators of brain homeostasis and central nervous system (CNS) disease. In the healthy brain, resident microglia are the predominant macrophage cell population; however, under conditions of blood-brain barrier leakage, peripheral monocytes/macrophages can infiltrate the brain and participate in CNS disease pathogenesis. Distinguishing these two populations is often challenging, owing to a paucity of universally accepted and reliable markers. To identify discriminatory marker sets for microglia and peripheral monocytes/macrophages, we employed a large meta-analytic approach using five published murine transcriptional datasets. Following hierarchical clustering, we filtered the top differentially expressed genes (DEGs) through a brain cell type-specific sequencing database, which led to the identification of eight microglia and eight peripheral monocyte/macrophage markers. We then validated their differential expression, leveraging a published single cell RNA sequencing dataset and quantitative RT-PCR using freshly isolated microglia and peripheral monocytes/macrophages from two different mouse strains. We further verified the translation of these DEGs at the protein level. As top microglia DEGs, we identified P2ry12 , Tmem119, Slc2a5 and Fcrls , whereas Emilin2 , Gda, Hp and Sell emerged as the best DEGs for identifying peripheral monocytes/macrophages. Lastly, we evaluated their utility in discriminating monocyte/macrophage populations in the setting of brain pathology (glioma), and found that these DEG sets distinguished glioma-associated microglia from macrophages in both RCAS and GL261 mouse models of glioblastoma. Taken together, this unbiased bioinformatic approach facilitated the discovery of a robust set of microglia and peripheral monocyte/macrophage expression markers to discriminate these monocyte populations in both health and disease. Electronic supplementary material The online version of this article (10.1186/s40478-019-0665-y) contains supplementary material, which is available to authorized users.

Protective Microglial Subset in Development, Aging, and Disease: Lessons From Transcriptomic Studies

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DPP‐4 inhibitor reduces striatal microglial deramification after sensorimotor cortex injury induced by external force impact

“…Expression of microglia/macrophage gene Iba‐1, two microglia‐specific molecules P2ry12 and Tmem119 26 were all highly induced 3 days after CCI in both cortex and striatum of the ipsilateral hemisphere (Figure 5, vehicle vs sham). Their levels remain high and indistinguishable between drug treatments (Figure 5, sita or vilda).…”

Enzymatic dissociation induces transcriptional and proteotype bias in brain cell populations

“…Despite the increasing number of studies performing proteotype analysis of brain cells freshly isolated via ED (Flowers, Bell-Temin, Jalloh, Stevens, & Bickford, 2017; Haage et al, 2019; Sharma et al, 2015), it remains unexplored whether ED introduces biological artefacts in proteotype profiles of brain cells. Therefore, we investigated whether the type of cell isolation method could also alter the proteotype of brain cells.…”