Tlr7 Drives Sex Differences in Age- and AD-related Demyelination

Alzheimer's disease (AD) and other age-related disorders associated with demyelination exhibit sex differences. Here, we used single-nuclei transcriptomics to dissect the contributions of sex chromosomes and gonads in demyelination and AD. In a mouse model of demyelination, we identified the role of sex chromosomes and gonads in modifying microglia and oligodendrocyte responses before and after myelin loss. In an AD-related mouse model expressing APOE4, XY sex chromosomes heightened interferon response and tau-induced demyelination. The X-linked gene Toll-like receptor 7 (Tlr7) regulated sex-specific interferon response to myelin. Deletion of Tlr7 dampened sex differences while protecting against demyelination. Administering TLR7 inhibitor mitigated tau-induced motor impairment and demyelination in male mice, indicating that Tlr7 plays a role in the male-biased IFN-I response in aging- and AD-related demyelination.