Sameera Zia, Marianela E. Traetta, Charbel S. Baaklini, Brady P. Hammond, Rebecca K. John, Katherine Souter, Niels Meijns, Larry K. A. Afun, Sharmistha P. Panda, Fernando Gonzàlez Ibáñez, Mena K. Burr, Eva Dhupia, Abhisha M. Rathod, Andréia V. Faria, Dhruvish Zaveri, Sowmya Challa, Eugene Hahn, Sohrab B. Manesh, Kelly V. Lee, Madelene F. S. Ho, Timothy N. Friedman, Aislinn D. Maguire, Arina Pang, Olivia Farkas, B Szulc, Luiz Tenorio, Diya Vyas, Olivia R. La Caprara, Wolfram Tetzlaff, Sarthak Sinha, Greg J. Duncan, Anastassia Voronova, Bradley J. Kerr, Marie‐Ève Tremblay, Jeff Biernaskie, Geert J. Schenk, Jason R. Plemel
Multiple sclerosis (MS) is a chronic, inflammatory condition characterized by neurodegeneration and lost myelin, or demyelination. This lost myelin may be regenerated in people with MS through a process called remyelination, that is prone to failure and is impaired with age. Remyelination is facilitated by microglia but our understanding of the microglial response during remyelination is incomplete. Here, we profile the microglial response during remyelination in the lysolecithin mouse model using single-cell RNA sequencing and find several distinct microglial states during the early stages of remyelination that coalesce into a resolved state defined by the presence of myelin transcripts, a state also present in MS brains. We also observe a delay in the appearance of several microglial states with age, in concordance with delayed remyelination. This multi-faceted microglial response during efficient remyelination provides the basis of multi-faceted microglia-specific targets for future MS therapies. Microglial states throughout remyelination are incompletely understood. Here, the authors show that microglia form several states during the early stages of remyelination that coalesce into a partially resolved state that is dysregulated with age.