α- Linolenic acid modulates phagocytosis of extracellular Tau and induces microglial migration

Abstract

The seeding effect of extracellular Tau species is an emerging aspect to study the Tauopathies in Alzheimers disease. Tau seeds enhance the propagation of disease along with its contribution to microglia-mediated inflammation. Omega-3 fatty acids are known to exert the anti-inflammatory property to microglia by modulating cell membrane compositions that influence various receptors expression and signaling cascade. The immunomodulatory function of omega-3 fatty acids exerts anti-inflammatory properties to microglia. Owing to the imparted anti-inflammatory nature enhance phagocytosis and increased migration property has been observed in microglia. The increased phagocytosis of extracellular Tau monomer and aggregates has been observed upon ALA exposure to microglia cells. The intracellular degradation of internalized Tau species was targeted by early and late endosomal markers Rab5 and Rab7. The increased levels of LAMP-2A and colocalization with internalized Tau indicated the degradation via lysosome. These results indicate the degradation of internalized Tau species in the presence of ALA instead of getting accumulated in the cell. The enhanced migratory ability of microglia in the presence of ALA induces the MTOC repolarization. Tau seeds greatly contribute to the spread of disease, one way to reduce the spreading is to reduce the presence of extracellular Tau seed. Microglia could be influenced to reduce extracellular Tau seed with dietary fatty acids. Our results suggest that dietary fatty acids ALA significantly enhances phagocytosis and intracellular degradation of internalized Tau. Enhanced migration supports the phagocytosis process. Our approach provides insights into the beneficial role of ALA as an anti-inflammatory dietary supplement to treat AD.