Transplantation of iPSC-derived neural progenitor cells promotes clinical recovery and repair in response to murine coronavirus-induced neurologic disease

Intracranial inoculation of susceptible strains of mice with the neuroadapted JHM strain of mouse hepatitis virus (JHMV, a member of the Coronaviridae family of viruses) results in an acute encephalomyelitis characterized by widespread growth of virus in astrocytes, microglia, and oligodendrocytes with relative sparing of neurons. Virus-specific CD4+ and CD8+ T cells infiltrate into the central nervous system in response to infection and control viral replication through secretion of interferon gamma as well as cytolytic activity. Nonetheless, virus persists in white matter tracts, and animals develop an immune-mediated demyelinating disease in which both T cells and macrophages amplify white matter damage. For the past decade, we have explored the therapeutic potential of human neural progenitor cells derived from pluripotent stem cells in promoting clinical recovery associated with remyelination of demyelinated axons following intraspinal transplantation. This chapter highlights recent studies from our laboratories demonstrating that tissue repair is associated with the emergence of regulatory T cells in response to transplantation of NPCs. © 2021 Elsevier Inc. All rights reserved.

Microglia influence host defense, disease, and repair following murine coronavirus infection of the central nervous system.

The present study examines functional contributions of microglia in host defense, demyelination, and remyelination following infection of susceptible mice with a neurotropic coronavirus. Treatment with PLX5622, an inhibitor of colony stimulating factor 1 receptor (CSF1R) that efficiently depletes microglia, prior to infection of the central nervous system (CNS) with the neurotropic JHM strain of mouse hepatitis virus (JHMV) resulted in increased mortality compared with control mice that correlated with impaired control of viral replication. Single cell RNA sequencing (scRNASeq) of CD45+ cells isolated from the CNS revealed that PLX5622 treatment resulted in muted CD4+ T cell activation profile that was associated with decreased expression of transcripts encoding MHC class II and CD86 in macrophages but not dendritic cells. Evaluation of spinal cord demyelination revealed a marked increase in white matter damage in PLX5622-treated mice that corresponded with elevated expression of transcripts encoding disease-associated proteins Osteopontin (Spp1), Apolipoprotein E (Apoe), and Triggering receptor expressed on myeloid cells 2 (Trem2) that were enriched within macrophages. In addition, PLX5622 treatment dampened expression of Cystatin F (Cst7), Insulin growth factor 1 (Igf1), and lipoprotein lipase (Lpl) within macrophage populations which have been implicated in promoting repair of damaged nerve tissue and this was associated with impaired remyelination. Collectively, these findings argue that microglia tailor the CNS microenvironment to enhance control of coronavirus replication as well as dampen the severity of demyelination and influence repair.