Unique microglia recovery population revealed by single-cell RNAseq following neurodegeneration

Microglia are brain immune cells that constantly survey their environment to maintain homeostasis. Enhanced microglial reactivity and proliferation are typical hallmarks of neurodegenerative diseases. Whether specific disease-linked microglial subsets exist during the entire course of neurodegeneration, including the recovery phase, is currently unclear. Taking a single-cell RNA-sequencing approach in a susceptibility gene-free model of nerve injury, we identified a microglial subpopulation that upon acute neurodegeneration shares a conserved gene regulatory profile compared to previously reported chronic and destructive neurodegeneration transgenic mouse models. Our data also revealed rapid shifts in gene regulation that defined microglial subsets at peak and resolution of neurodegeneration. Finally, our discovery of a unique transient microglial subpopulation at the onset of recovery may provide novel targets for modulating microglia-mediated restoration of brain health. Overall design: scRNA-Seq was performed on microglial cells isolated from the ipsilateral and contralateral ventral pons of CX3CR1GFP/wt mice that underwent unilateral facial nerve axotomy at 12 weeks of age. The contralateral ventral pons of un-operated 12-week-old CX3CR1GFP/wt was used as baseline control (Day 0 post nerve transection) for the analysis. Three replicates were used per time point (Day 0, 7 and 30 post axotomy). mCEL-Seq2 protocol was used for single cell sequencing (Hashimshony et al. 2016, Herman et al. 2018).

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Tay TL, Sagar, Dautzenberg J, Grün D, Prinz M