Alzheimer’s Disease: Spirochetes, Biofilm and the Immune System

Alzheimers Disease: A Novel Hypothesis Integrating Spirochetes, Biofilm,

and the Immune System

Herbert B. Allen*, Diego Morales, Krister Jones and Suresh Joshi

Drexel University College of Medicine, Philadelphia, USA


In the light of recent studies showing the presence of spirochetes in the brains of Alzheimer’s disease (AD) patients, we have studied (post mortem) the hippocampus region in the brains of similarly affected AD patients utiliz- ing both pathology and immunohistochemistry. Our ndings demonstrate that the plaques, which are characteristically found in AD brains, reveal the presence of bio lms. These bio lms are undoubtedly made by the spirochetes present there; further, we have also found that the bio lms co-localize with the β amyloid that is a signature nding in the disease. Also, we have shown activation of Toll-like receptor 2 in the same areas. We postulate this is related to the disease because this innate immune system molecule cannot penetrate the bio lm to destroy the spirochetes present there, so, inasmuch as it is activated, it destroys the surrounding tissue instead. We compare this destruction to that which is caused by activation of the adaptive immune system, which leads to much more severe devastation, much more rapidly.

Keywords: Immune system; Hippocampus; Osteoarthritis; Bio lms Introduction

Recently, spirochetes have been found in the brains of Alzheimer’s dis- ease (AD) patients [1-3] and, even more recently, the pathology of general paresis of the insane (neurosyphilis) has been shown to be exactly similar to that of AD [4]. In addition, joints in osteoarthritis, another chronic dis- ease, have recently been shown to contain bio lms despite the joints being culture negative [5]. In each of these disease states, dental spirochetes and Borrelia burgdorferi spirochetes have been implicated [6,7]. In a similar fashion, chronic otitis media has been shown to contain bio lms while cul- tures have been negative [8]. Most organisms have the capability of making bio lms, and, once made, the now “slime”-covered organisms are no longer able to be cultured routinely nor be treated by antibiotics.

We recently have found that normal skin ora staphylococci make bio lms, occlude eccrine sweat ducts, activate the innate immune sys- tem (Toll-like receptor 2 [TLR 2]) and thereby trigger pathways to create the signs and symptoms of atopic dermatitis, another chronic disease [9]. We have applied the same pathological and immunohisto- chemical procedures that were used in the atopic dermatitis study to the specimens from AD to determine whether bio lms were present and whether the innate immune system was involved.


Seven hippocampal specimens from patients who had previously been con rmed both clinically and pathologically (post mortem) to have Alzheimer’s disease were examined by ve pathologists. Ten con- trol hippocampal specimens, from age and sex matched patients who died of unrelated, non-cerebral diseases and/or causes were included for study. All specimens were stained with hematoxylin and eosin (H+E), periodic acid Schi (PAS), Congo red routine stains; all speci- mens were also stained with treponema pallidum (TPI), β amyloid, CD 282 (TLR 2) and CD 284 (TLR 4) immunostains. e technique for these stains was as previously published [9]. PAS and β amyloid stains were applied sequentially to the specimens and were examined. Rou- tine light microscopy was employed. e specimens were not “blinded” because by gross examination alone, the AD specimens could be distin- guished from the controls.


e AD brains showed the expected histologic ndings of plaques,

J Neuroinfect Dis
ISSN: 2314-7326 JNID an open access journal

tangles, curly bers, Tau protein, and β amyloid on routine staining. (Figures 1-3) None of the controls demonstrated these. e PAS stained positively in the same locations as the plaques in AD patients; the con- trols showed no PAS positivity. e β amyloid/PAS preparations that were sequentially stained on the same specimens showed co-localiza- tion of the two stains. (Figure 4) CD 282, representing TLR 2, showed focal staining in the AD brains with nothing being evident in the con- trols. (Figures 4-6) CD 284 showed minimal reactivity.


We believe the positive PAS and Congo red ndings con rm the pres- ence of bio lms in the AD brains. e PAS stains the extracellular polysac- charide material that makes up the bulk of the bio lms and the Congo red stains the amyloid that forms the infrastructure of the bio lm. e amyloid

Figure 1: Hippocampus AD. The plaques of AD are well visualized in this speci- men. Congo red stain 10X.


Figure 2: Hippocampus AD. PAS staining indicates presence of bio lms 10X. 


Figure 3: Hippocampus AD. β amyloid which is the hallmark of AD 10X. 


Figure 4: Hippocampus AD. β amyloid and PAS co-localized in the plaques. PAS and β amyloid stains (combined) 40X. 


Figure 5: Hippocampus AD. TLR 2 seen throughout the tissue. CD 282 10 X. 



Figure 6: Hippocampus AD. Positive staining with CD 282 (TLR 2) 40 X. 


 *Corresponding author: Herbert B. Allen, Drexel University College of Medicine, Philadelphia, USA, Tel: 2157625550; Fax: 215 7625570; E-mail:

Received December 01, 2015; Accepted December 30, 2015; Published January 02, 2016

Citation: Allen HB, Morales D, Jones K, Joshi S (2016) Alzheimer’s Disease: A Novel Hypothesis Integrating Spirochetes, Bio lm, and the Immune System. J Neuroinfect Dis 7:200. doi:10.4172/2314-7326.1000200

Copyright: © 2016 Allen HB, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Volume 7 • issue 1

Citation: Allen HB, Morales D, Jones K, Joshi S (2016) Alzheimer’s Disease: A Novel Hypothesis Integrating Spirochetes, Bio lm, and the Immune System. J Neuroinfect Dis 7:200. doi:10.4172/2314-7326.1000200

Figure 6: Hippocampus AD. Positive staining with CD 282 (TLR 2) 40 X.

J Neuroinfect Dis
ISSN: 2314-7326 JNID an open access journal

Page 2 of 3

Figure 7: Representative bio lm (slime); photo of Malassezia furfur making bio lms in culture.

itself is not responsible for the PAS positivity as it is, at most, an oligosac- charide. e co-localization of the β amyloid and the PAS stain demon- strates that nding as well by positioning the bio lm and the β amyloid in the same place. e CD 282 positivity reveals activation of the innate immune system. ere was a concern that the positive TLR 2 staining rep- resented lipofuscin which is a marker of senescence. In some instances, it did; namely, the intracytoplasmic and the clumped material that was noted. Two controls also showed clumped material that stained positively. In the AD patients, the TLR 2 staining that was extracellular, and non-clumped, we considered actual TLR 2.

e presence (by polymerase chain reaction) of spirochetes (75% dental and 25% Lyme Borrelia) has previously been reported, as has the total similarity of AD and general paresis (tertiary syphilis) as relates to pathology [1,4]. e two diseases therefore are similar save for be- ing caused by di erent spirochetal organisms. Spirochetes have been shown to form bio lms, [10] and it appears that is occurring in the a icted brains. Most likely, they are creating bio lms via the “quo- rum sensing” mode: when there are su cient organisms present, they “sense” it and spin out bio lms to protect themselves. is renders them impenetrable not only to antibiotics, but to the immune system as well. (One can get a better sense of this from the photo of a representative bio lm as seen in Figure 7. Organisms have been shown to form bio- lms when exposed to salt, water, alcohol, low dose antibiotics, etc. as well as via the quorum sensing mechanism [11].

e spirochetes take considerable time to divide (90 days); [12] thus, the process to build a quorum is lengthy. is may account in part for the prolonged time for the disease to develop (up to 50 years for syphilitic de- mentia) [13]. e presence of TLR 2 may help explain the disease process. e organisms enter the brain during a bacteremic phase of a dental pro- cedure or during dissemination of Lyme Borrelia. ( e same process oc- curs in secondary syphilis with the organisms being systemic during that stage in the disease.) e dental spirochetes and the Lyme spirochetes di- vide slowly, as previously noted, accumulate a quorum, spin out bio lms, and cause the activation of TLR 2. TLR 2, incidentally, has previously been found, but not shown pathologically, in AD [14,15]. We are thus present- ing the same ndings in a di erent way. A mechanism by which TLR 2 is activated has recently been elucidated [16,17].

TLR 2 ordinarily combats gram positive organisms by coating and kill- ing them with TNF-α; however, TLR 2 has been shown to be upregulated by spirochetes even though the spirochetes themselves are weakly gram negative [18]. Once a bio lm is made, the TLR 2 cannot penetrate the slime coating and thus cannot destroy the organisms inside. e TLR 2 is

Volume 7 • Issue 1 • 1000200

Citation: Allen HB, Morales D, Jones K, Joshi S (2016) Alzheimer’s Disease: A Novel Hypothesis Integrating Spirochetes, Bio lm, and the Immune System. J Neuroinfect Dis 7:200. doi:10.4172/2314-7326.1000200

Disruption of dental plaque; Ixodes tick bite; syphilitic chancre (for comparison)


Organisms travel to brain (hippocampus 4 cm from posterior pharynx)

Gradually multiply and achieve quorum

Create bio lm (which is impenetrable)

Innate immune (TLR 2) system activation

Neural tissue destroyed (innocent bystanders) by TLR 2

Table 1: Alzheimer’s Disease Cascade.
“primed”, and the surrounding tissue, as an “innocent by stander” is con-

ceivably destroyed. e cascade of events is pictured in (Table 1).

Contrasted with the innate immune system, it is of exceeding in- terest what occurs when the activated adaptive immune system is in- volved. is takes place in the a ermath of a cerebrovascular accident (CVA or stroke) [19] where the blood brain barrier is breached. B lym- phocytes are then capable of entering the brain; IgG is noted in large areas of neural tissue, and T cells are recruited and enter the previously forbidden zone. e occurrence of Alzheimer’s disease a er a stroke is rapid (1-3 years), compared to the 30-50 years ordinarily noted [13]. e adaptive immune system with complement, alternate complement, opsonization, killer T cells, etc. eradicates organisms with much greater e ciency likening it to a “machine gun vs a bow and arrow” when com- pared to the innate immune system. However, just as in the situation with the innate immune system, it cannot penetrate the bio lm either, thus it destroys greater amounts of the surrounding neural tissue much more rapidly.

Consequently, in all likelihood, it is not the presence of the organ- isms, or the bio lms, or the β amyloid that is the etiology of AD. It is rather the reaction of the immune system to these organisms coated with bio lms that leads to the disease with all its manifestations. As it has been previously discussed, killing these organisms before they arrive at the brain or before they do damage (create bio lms) is exceed- ingly important in this disease [20]. Moreover, it will likely lead to a “cure” of this woeful in rmity, just as has been the case in syphilitic dementia.


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