Gasdermin D activation in oligodendrocytes and microglia drives inflammatory demyelination in progressive multiple sclerosis.

Neuroinflammation coupled with demyelination and neuro-axonal damage in the central nervous system (CNS) contribute to disease advancement in progressive multiple sclerosis (P-MS). Inflammasome activation accompanied by proteolytic cleavage of gasdermin D (GSDMD) results in cellular hyperactivation and lytic death. Using multiple experimental platforms, we investigated the actions of GSDMD within the CNS and its contributions to P-MS. Brain tissues from persons with P-MS showed significantly increased expression of GSDMD, NINJ1, IL-1β, and -18 within chronic active demyelinating lesions compared to MS normal appearing white matter and nonMS (control) white matter. Conditioned media (CM) from stimulated GSDMD human macrophages caused significantly greater cytotoxicity of oligodendroglial and neuronal cells, compared to CM from GSDMD macrophages. Oligodendrocytes and CNS macrophages displayed increased Gsdmd immunoreactivity in the central corpus callosum (CCC) of cuprizone (CPZ)-exposed Gsdmd mice, associated with greater demyelination and reduced oligodendrocyte precursor cell proliferation, compared to CPZ-exposed Gsdmd animals. CPZ-exposed Gsdmd mice exhibited significantly increased G-ratios and reduced axonal densities in the CCC compared to CPZ-exposed Gsdmd mice. Proteomic analyses revealed increased brain complement C1q proteins and hexokinases in CPZ-exposed Gsdmd animals. [F]FDG PET imaging showed increased glucose metabolism in the hippocampus and whole brain with intact neurobehavioral performance in Gsdmd animals after CPZ exposure. GSDMD activation in CNS macrophages and oligodendrocytes contributes to inflammatory demyelination and neuroaxonal injury, offering mechanistic and potential therapeutic insights into P-MS pathogenesis.