Abrogation of type-I interferon signalling alters the microglial response to Aβ_1-42

Neuroinflammation and accompanying microglial dysfunction are now appreciated to be involved in Alzheimer's disease (AD) pathogenesis. Critical to the process of neuroinflammation are the type-I interferon (IFN) family of cytokines. Efforts to phenotypically characterize microglia within AD identify distinct populations associated with type-I IFN signalling, yet how this affects underlying microglial function is yet to be fully elucidated. Here we demonstrate that Aβ_1-42 exposure increases bioactive levels of type-I IFN produced by primary microglia alongside increased expression of type-I IFN related genes. Primary microglia isolated from brains of APP_swePS1_ΔE9 mice with ablated type-I IFN signalling show an increased phagocytic ability to uptake FITC-Aβ_1-42. Correlative assessment of plaque sizes in aged APP_swePS1_ΔE9 mice with abrogated type-I IFN signalling show unchanged deposition levels. Microglia from these mice did however show alterations in morphology. This data further highlights the role of type-I IFN signalling within microglia and identifies a role in phagocytosis. As such, targeting both microglial and global type-I IFN signalling presents as a novel therapeutic strategy for AD management.