TLR4 and Alzheimer disease: GAS can induce a transformation of microglia from the M1 pro-inflammatory phenotype to the M2 anti-inflammatory phenotype, which is achieved by the inhibition of various pathways, including those involving TLR4/TRAF6/NF-κB, PI3K/AKT, and Nrf2/STAT3, thereby reducing neuroinflammation and improving neuroinflammatory damage, and exerting an anti-inflammatory effect in neurological disorders such as AD and epilepsy.