Microglia are essential for brain homeostasis, yet their roles in the aged brain remain poorly defined. Using microRNA (miRNA) profiling, cellular-resolution spatial transcriptomics, and bulk proteomics in 21-month-old mice, we characterize sex-dimorphic responses to microglial depletion via CSF1R inhibition (PLX5622 treatment). Microglia-enriched miRNAs, notably miR-146a-5p and miR-223-3p, were downregulated across different brain regions in both sexes. Transcriptional responses were sex dimorphic: females showed predominantly cell-type-specific downregulation, while males showed bidirectional changes including upregulation of Lzts3, Shank3, and Fgfbp1 alongside downregulation of Ang. Proteomic changes were larger in magnitude and independent from mRNA changes: males exhibited 295 differentially expressed proteins (DEPs) versus 34 in females (8.7-fold difference). Male DEPs had opposing directional shifts in synaptic vesicle proteins (upregulated) and mitochondrial ATP synthesis machinery (downregulated). These data describe sex-dimorphic molecular consequences of microglial loss in the aged brain and identify candidate post-transcriptional mechanisms warranting further investigation.
Amila Beganovic, M. Flotho, Jin-Xiu Li et al.· bioRxiv· 0 citations
Aging is associated with immune dysregulation in the brain and is the greatest risk factor for many neurodegenerative diseases. Rejuvenation interventions can mediate beneficial effects. Microglia are major contributors to neurodegenerative disease progression; however, the molecular changes underlying brain aging and rejuvenation remain poorly understood at the single-cell level. We identified and benchmarked several reproducible microglial states and a core set of genes that drive microglial activation in the mouse brain. We investigated microglial heterogeneity and examined the impact of aging and parabiosis-mediated exposure to young and old blood on microglial subpopulations across four brain regions: the cerebellum, cortex, hippocampus, and striatum. We revealed region-specific differences in microglial composition and age-related changes. The cerebellum consistently emerged as the most responsive region, whereas the striatum showed minimal responsiveness to parabiosis interventions. These findings highlight regional vulnerability and inform microglia-targeted strategies to modulate brain aging.
H. Naz, Nannan Lu, Caroline C. Escoubas et al.· Cell Reports· 0 citations
Routine and accessible plasma measures can be leveraged to recover reproducible, biologically distinct progression modules that improve characterization of heterogeneous AD and have practical value for risk stratification, trial enrichment, or treatment monitoring.
R. R. Butler, M. Brown, A. Weber et al.· medRxiv· 0 citations
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