The Injured Sciatic Nerve Atlas (iSNAT), insights into the cellular and molecular basis of neural tissue degeneration and regeneration
- University of Michigan-Ann Arbor, United States
- University of Michigan Medical School, United States
- University of California, Los Angeles, United States
- University of South Carolina, United States
- University of Michigan, United States
Abstract
Upon trauma, the adult murine PNS displays a remarkable degree of spontaneous anatomical and functional regeneration. To explore extrinsic mechanisms of neural repair, we carried out single cell analysis of naïve mouse sciatic nerve, peripheral blood mononuclear cells, and crushed sciatic nerves at 1-day, 3-days, and 7- days following injury. During the first week, monocytes and macrophages (Mo/Mac) rapidly accumulate in the injured nerve and undergo extensive metabolic reprogramming. Proinflammatory Mo/Mac in the injured nerve show high glycolytic flux compared to Mo/Mac in blood and dominate the early injury response. They subsequently give way to inflammation resolving Mac, programmed toward oxidative phosphorylation. Nerve crush injury causes partial leakiness of the blood-nerve-barrier, proliferation of endoneurial and perineurial stromal cells, and accumulation of select serum proteins. Micro-dissection of the nerve injury site and distal nerve, followed by single-cell RNA-sequencing, identified distinct immune compartments, triggered by mechanical nerve wounding and Wallerian degeneration, respectively. This finding was independently confirmed with Sarm1-/- mice, where Wallerian degeneration is greatly delayed. Experiments with chimeric mice showed that wildtype immune cells readily enter the injury site in Sarm1-/- mice, but are sparse in the distal nerve, except for Mo. We used CellChat to explore intercellular communications in the naïve and injured PNS and report on hundreds of ligand-receptor interactions. Our longitudinal analysis represents a new resource for nerve regeneration, reveals location specific immune microenvironments, and reports on large intercellular communication networks. To facilitate mining of scRNAseq datasets, we generated the injured sciatic nerve atlas (iSNAT): https://cdb-rshiny.med.umich.edu/Giger_iSNAT/
Data availability
All scRNA-seq datasets (fastq files and Seurat objects) are available online through the Gene Expression Omnibus (GEO) database https://www.ncbi.nlm.nih.gov/geo , accession number GSE198582.All code for iSNAT is available at https://github.com/GigerLab/iSNAT
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Injured Sciatic Nerve Atlas (iSNAT)NCBI Gene Expression Omnibus, GSE198582.
Article and author information
Author details
Daniel H Geschwind
Funding
Adelson Family Foundation (APNRR)
- Jeffery L Twiss
- Daniel H Geschwind
- Roman J Giger
NIH Blueprint for Neuroscience Research (MH119346)
- Roman J Giger
NIH Blueprint for Neuroscience Research (R01DC018500)
- Gabriel Corfas
NIH Blueprint for Neuroscience Research (T32 NS07222)
- Ashley L Kalinski
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Ethics
Animal experimentation: All procedures involving mice were approved by the Institutional Animal Care and Use Committees (IACUC) of the university of Michigan (PRO 00009851) and performed in accordance with guidelines developed by the National Institutes of Health
Copyright
© 2022, Zhao et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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The Injured Sciatic Nerve Atlas (iSNAT), insights into the cellular and molecular basis of neural tissue degeneration and regeneration
eLife 11:e80881.
https://doi.org/10.7554/eLife.80881
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