Salivary Aβ Secretion and Altered Oral Microbiome in Mouse Models of AD.

BACKGROUND: Beta amyloid (Aβ) peptide containing plaque aggregations in the brain are a hallmark of Alzheimer's Disease (AD). However, Aβ is produced by cell types outside of the brain suggesting that the peptide may serve a broad physiologic purpose.
OBJECTIVE: Based upon our prior work documenting expression of amyloid β precursor protein (APP) in intestinal epithelium we hypothesized that salivary epithelium might also express APP and be a source of Aβ.
METHODS: To begin testing this idea, we compared human age-matched control and AD salivary glands to C57BL/6 wild type, AppNL-G-F , and APP/PS1 mice.
RESULTS: Both male and female AD, AppNL-G-F , and APP/PS1 glands demonstrated robust APP and Aβ immunoreactivity. Female AppNL-G-F mice had significantly higher levels of pilocarpine stimulated Aβ 1-42 compared to both wild type and APP/PS1 mice. No differences in male salivary Aβ levels were detected. No significant differences in total pilocarpine stimulated saliva volumes were observed in any group. Both male and female AppNL-G-F but not APP/PS1 mice demonstrated significant differences in oral microbiome phylum and genus abundance compared to wild type mice. Male, but not female, APP/PS1 and AppNL-G-F mice had significantly thinner molar enamel compared to their wild type counterparts.
CONCLUSION: These data support the idea that oral microbiome changes exist during AD in addition to changes in salivary Aβ and oral health. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.