Genetic, Transcriptome, Proteomic, and Epidemiological Evidence for Blood-Brain Barrier Disruption and Polymicrobial Brain Invasion as Determinant Factors in Alzheimer’s Disease

Carter, Chris J.

Many viruses including Herpes viruses (HSV-1 and HHV6), the Borna disease virus, rabies virus, and the influenza A virus are known to use the olfactory route to invade the brain [14] . It has also been shown in mice that injection of HSV-1 into the olfactory bulbs leads to viral migration into the amygdala and hippocampus via the olfactory nerve and the locus coeruleus [176] . Nasal inoculation with C. pneumoniae in mice also results in cerebral A␤ deposition suggesting use of the olfactory route [118] . The nasal epithelial mucosa forms an important physical and immune barrier to invading pathogens [177, 178] . While immunosenescence occurs in many mucosal sites during aging, nasopharyngeal tissue function is more resistant and remains intact during aging with notable signs of immunosenescence seen only in the very elderly [179] . The nasal route of pathogen entry would thus also be restricted to the aged population.