Pathological interplay between microglia and macrophages in AD. Pathological trigger is detected by Pattern-Recognition Receptors (PRRs) in microglia recognized by pathogen-associated molecular patterns (PAMPs) or danger-associated molecular patterns (DAMPs). The protein cascade induces microglia to initiate immune response at the injury site by acquiring M1 and M2 macrophages. Furthermore, microglia fuse with soluble Aβ through cell surface receptors (CSRs)/ Toll-like receptors (TLRs) and amyloid fibrils resulting in its activation and leading to phagocytosis, clearance and degradation of Aβ. The engulfment of Aβ turn on the endo-lysosomal pathway in microglia. On the other hand, prolonged activation of microglia leads to release of pro-cytokines that induces pro-inflammatory cascade.