Potential role of antimicrobial peptides in the early onset of Alzheimer's disease.

Cerebral aggregation of amyloid-β (Aβ) is thought to play a major role in the etiology of Alzheimer's disease. Environmental influences, including chronic bacterial or viral infections, are thought to alter the permeability of the blood-brain barrier (BBB) and thereby facilitate cerebral colonization by opportunistic pathogens. This may eventually trigger Aβ overproduction and aggregation. Host biomolecules that target and combat these pathogens, for instance, antimicrobial peptides (AMPs) such as Aβ itself, are an interesting option for the detection and diagnostic follow-up of such cerebral infections. As part of the innate immune system, AMPs are defensive peptides that efficiently penetrate infected cells and tissues beyond many endothelial barriers, most linings, including the BBB, and overall specifically target pathogens. Based on existing literature, we postulate a role for labeled AMPs as a marker to target pathogens that play a role in the aggregation of amyloid in the brain.