Focusing on the Essential Role of Biofilms in Alzheimer’s Disease

Biofilms are made by microbes and are exceedingly common in nature. On examination of
pathological specimens from the hippocampi in Alzheimer’s disease (AD) brains, biofilms have been
observed both intra and extra-cellularly. Borrelia burgdorferi of Lyme disease and T. denticola
(representative of the dental organisms) have been found by PCR analysis, and Borrelia burgdorferi
has been cultured from AD brains. Simultaneously with making biofilms in vitro, these cultivated
Borrelia have been shown to make beta amyloid precursor protein (ABPP) and amyloid beta (Aβ) in
pure culture. Comparatively, in the intracellular location in vivo, the Aβ (formed by the spirochetes
while making biofilm), when meshing with tau protein, causes tau to be phosphorylated by a known
interaction. When tau is hyperphosphorylated tau (p-tau), it no longer functions to stabilize neuronal
dendrites, and those dendrites disintegrate. Extracellular biofilms are coated with Aβ (which is
antimicrobial). Further, those biofilms attract Toll-like receptor 2 from the innate immune system; this
molecule attempts to kill the spirochetes, but is ineffective, because it is unable to penetrate the
biofilm. NFkB, one of the intermediates in the MyD88 pathway generated by TLR2, catalyzes beta
amyloid converting enzyme which, in turn, catalyzes beta and gamma secretase that cleave ABPP to
Aβ. Consequently, in the formation of biofilm, Aβ is created; and, in the TLR2/MyD88 response to the
“spirochete-coated” biofilm, Aβ is also created. Finally, p-tau, the other major element of the
pathology, is directly related to the creation of the biofilms. Biofilms are thus integral to the pathology
of AD. The various factors that worsen the disease have recently been outlined and their presence
and influence in the above pathway have been summarized. Fewer factors lead to the improvement in
the disease, but the factor that is most logical is the administration of an antibiotic to kill the
spirochetes before they make biofilms or before they even arrive at the brain and begin the process.