Antimicrobial peptides act as a component of brain immunity against microbes in Alzheimer's disease

Alzheimer's disease is a most prevalent type of dementia in elderly people. Extracellular accumulation of Amyloid-β (Aβ) and intracellular aggregation of Tau NFTs in the brain is proposed to be a key factor in the development of Alzheimer's disease. A fast-growing body of evidence strengthened the infectious hypothesis of sporadic type of AD. Recent clinical studies focused on the characterizing of antimicrobial peptides (AMPs), because it has been documented that some pathogenic microorganism, such as herpesviruses and particular bacterial strains, are generally present in AD individuals. And also, the environmental factors, such as persistent bacterial or viral infections, change the blood-brain barrier's (BBB) permeability, making it easier for opportunistic pathogens to colonise the brain. This review highlights the potential role of Aβ, which perform antimicrobial activity against diverse pathogens, significantly encouraging its role in the innate immune response. While mammalian amyloid is linked with disease, numerous microbes form amyloid fibrils to embattle the biofilm that prevent the cells from the surrounding environment. According to the microbial AD hypothesis, Aβ clumps up to combat the microbial infection.