Anti-CLEC7A nanobody in situ engineering promotes amyloid-β oligomers clearance by CAR-microglia to alleviate Alzheimer's disease pathology in mice

Chimeric antigen receptor microglia (CAR-M)-mediated amyloid-β oligomers (AβO) phagocytosis shows great promise in Alzheimer's disease (AD) treatment, however, the limited AβO degradation of CAR-M compromises their anti-AβO potency. This work here reports an in situ engineered agonistic anti-C-type lectin domain containing 7 A (CLEC7A) nanobody to accelerate AβO degradation of CAR-M, augmenting their anti-AβO efficacy. Specifically, with the intranasal-delivered microglia-targeting lipid nanoparticles (LNP), this work generates an AβO-specific degradation-potentiated CAR-M by introducing dual mRNAs encoding AβO-specific CAR and anti-CLEC7A nanobody into the cerebral microglia. These data show that these engineered CAR-M exhibited superior phagocytic function and promoted intracellular AβO degradation via activating CLEC7A-spleen tyrosine kinase (SYK) signaling pathway through the local secretion of anti-CLEC7A nanobody. In the APP/PS1 mouse model of AD, these in situ reprogrammed CAR-M significantly reduced cerebral Aβ levels, suppressed neuroinflammation, and restored cognitive function. In sum, these findings demonstrate that potentiating AβO degradation within CAR-M effectively alleviates AD pathology, providing a promising therapeutic strategy for AD with broad application in other neurodegenerative diseases.