Why does HMW tau induce stronger glial activation than fibrillar tau without causing neurodegeneration?

HMW tau triggers robust microglial responses including Clec7a-positive rod microglia formation, yet doesn’t cause neurodegeneration or synapse loss unlike fibrillar tau. This dissociation between neuroinflammation and neuronal damage challenges current understanding of tau toxicity mechanisms.

Gap type: unexplained_observation Source paper: Tau seeding and spreading in vivo is supported by both AD-derived fibrillar and oligomeric tau. (2023, Acta neuropathologica, PMID:37341831)

[“Comparative proteomics of microglia isolated from HMW tau-injected vs fibrillar tau-injected mouse brain identifies 15+ differentially expressed genes in the inflammatory pathway”, “HMW tau stimulation of microglial cultures triggers distinct cytokine/chemokine profile (multiplex ELISA) vs fibrillar tau at 24h”, “RNA-seq of Clec7a+ microglia sorted from HMW tau-injected mice shows specific neuroprotective gene signature distinct from fibrillar tau response”, “Selective blockade of identified glial activation pathways (e.g., TREM2 or complement) reduces neurotoxicity without affecting HMW tau clearance”]