Engineered W20-LT fusion protein ameliorates cognitive deficits and amyloid pathology in Alzheimer's mice

Alzheimer's disease (AD) is characterized by the accumulation of Amyloid-β (Aβ) oligomers, which are highly neurotoxic and drive disease progression. Current therapeutic strategies, including peptides and antibodies, often struggle to effectively promote microglial phagocytosis and subsequent intracellular clearance of aggregated Aβ. Furthermore, dense Aβ accumulation can overwhelm lysosomal enzymatic hydrolysis, leading to lysosomal stress and dysfunction. This creates a critical gap in AD treatment, where a multi-pronged approach targeting Aβ, microglial uptake, and lysosomal clearance is needed.

Researchers engineered W20-LT, a multifunctional fusion protein designed to address these challenges. It comprises an Aβ oligomer-specific single-chain variable fragment (scFv), a microglia-targeting Tuftsin peptide, and a p62-LIR peptide to activate autophagy. In vitro assays compared W20-LT to its parental W20, evaluating microglial uptake and intracellular clearance of Aβ oligomers. In vivo, APPswe/PS1dE9 (APP/PS1) mice received a low-dose regimen of W20-LT (0.5 µg, every 3 days) or W20, with cognitive deficits and amyloid pathology as primary endpoints.

In vitro assays revealed that W20-LT significantly outperformed the parental W20 by promoting rapid microglial uptake of Aβ oligomers and enhancing their intracellular clearance via an autophagy-associated pathway.

In APP/PS1 mice, a low-dose regimen of W20-LT (but not W20) significantly ameliorated cognitive deficits and reduced amyloid pathology. Mechanistically, W20-LT treatment was associated with enhanced autophagy-lysosomal pathway activity, evidenced by increased LC3B-II levels and reduced p62 levels. Additionally, CatD and LAMP1 levels were downregulated, indicating improved lysosomal function and mitigation of neuroinflammation. These findings collectively demonstrate W20-LT's ability to target, clear, and process Aβ aggregates.