Inducible Nitric Oxide Synthase (NOS2) is Required for Oligodendrocyte Lineage Progression and Remyelination in Murine β-Coronavirus-Induced Neuroinflammation
Year: 2026
Type: preprint
Abstract: Background Multiple sclerosis (MS) and post-viral demyelinating encephalomyelitis are characterized by chronic central nervous system (CNS) inflammation, myelin sheath destruction, and impaired tissue repair. While inducible nitric oxide synthase (NOS2) is traditionally viewed as a cytotoxic mediator in acute neuroinflammation, its temporal role, from myelin loss to the long-term endogenous remyelination phase, has remained controversial and poorly defined. Using a murine β-coronavirus (MHV-RSA59) model of neuroinflammation, we investigated the requirement for NOS2 during the myelin loss and repair phase (days 30 to 60 post-infection). Method Age-matched C57BL/6 wild-type (WT) and NOS2-/-mice were intracranially inoculated with 10,000 PFU of RSA59. Animals were euthanized at defined time points (day 30 and day 60 post-infection) to harvest the tissue samples. Luxal Fast Blue (LFB) staining, immunofluorescence (IF), immunoblotting, immunohistochemistry, and flow cytometry were performed on the RSA59-infected brain and spinal cord samples of NOS2-/- and WT mice. Results Our recent findings revealed that NOS2-/- mice, compared to WT mice, showed persistent demyelinating plaques, reduced myelin restoration, as indicated by the expression of myelin-forming proteins, and a diminution of oligodendrocyte precursor cells (OPCs) and mature oligodendrocytes during the remyelination phase. This delayed regenerative process in the absence of NOS2 was associated with prolonged activation of CNS-resident microglia and an infiltrated myeloid cell population, which may lead to a dysregulated inflammatory environment in the CNS. Mechanistically, loss of NOS2 led to more phagocytic activity in CNS-resident microglia and infiltrating myeloid cells. Our findings establish that NOS2-derived signals are essential for clearing inflammatory debris and transitioning myeloid cells from a pro-inflammatory state toward a pro-regenerative phenotype, thereby creating a permissive microenvironment for myelin repair. Conclusion This study elucidates how NOS2 regulates the balance between pathological damage and tissue repair. Also, our current research highlights NOS2 not merely as a marker of inflammation, but as a crucial protective factor required for effective myelin regeneration in virus-induced neuroinflammatory demyelination.
Source: Research Square
Language: English
Subfield: Clinical Neurology
Field: Medicine
Domain: Health Sciences
Open Access status: green
Funders: Arthritis National Research Foundation, National Research Foundation, Department of Biotechnology, Ministry of Science and Technology, India, Indian Institute of Science Education and Research Kolkata, Directorate for Biological Sciences, Science and Engineering Research Board, Division of Emerging Frontiers
OpenAlex ID: W7225228043