Regulation of Tau Pathology by the Microglial Fractalkine Receptor

SummaryAggregates of the hyperphosphorylated microtubule-associated protein tau (MAPT) are an invariant neuropathological feature of tauopathies. Here, we show that microglial neuroinflammation promotes MAPT phosphorylation and aggregation. First, lipopolysaccharide-induced microglial activation promotes hyperphosphorylation of endogenous mouse MAPT in nontransgenic mice that is further enhanced in mice lacking the microglial-specific fractalkine receptor (CX3CR1) and is dependent upon functional toll-like receptor 4 and interleukin-1 (IL-1) receptors. Second, humanized MAPT transgenic mice lacking CX3CR1 exhibited enhanced MAPT phosphorylation and aggregation as well as behavioral impairments that correlated with increased levels of active p38 MAPK. Third, in vitro experiments demonstrate that microglial activation elevates the level of active p38 MAPK and enhances MAPT hyperphosphorylation within neurons that can be blocked by administration of an interleukin-1 receptor antagonist and a specific p38 MAPK inhibitor. Taken together, our results suggest that CX3CR1 and IL-1/p38 MAPK may serve as novel therapeutic targets for human tauopathies.Video Abstract To view the video inline, enable JavaScript on your browser. However, you can download and view the video by clicking on the icon belowHelp with MP4 filesOptionsDownload video (29775 K)

► Microglial activation promotes MAPT phosphorylation and aggregation ► CX3CR1 deficiency enhances MAPT pathology and promotes behavioral disturbances ► A soluble factor from microglia induces MAPT phosphorylation via a p38 MAPK pathway ► Induction of MAPT phosphorylation is dependent upon TLR4 and IL-1 signaling