Oral microbiome and serological analyses on association of Alzheimer's disease and periodontitis

To investigate the association between Alzheimer's disease (AD) and periodontitis in the aspects of periodontal status, serological markers, and oral microbiome.Twenty AD and 20 healthy subjects were enrolled in this age- and gender-matched case-control study. Clinical periodontal parameters and serum biomarkers, including amyloid β42 (Aβ42 ), Tau, phosphorylated Tau (pTau), triglyceride, pro-inflammatory cytokines, and anti-Porphyromonas gingivalis lipopolysaccharide (LPS) antibody were examined. The saliva samples were analyzed for oral microbiome composition.Alzheimer's disease patients with Clinical Dementia Rating (CDR) ≥1 exhibited significantly more clinical attachment loss (CAL) than those with lower CDR. The levels of serum Tau protein, hsCRP and anti-P. gingivalis LPS antibody were markedly elevated in the AD group compared with the control group. Serum pTau protein level was positively correlated with anti-P. gingivalis LPS antibody titer. Moreover, the increased abundances of Capnocytophaga sp ora clone DZ074, Eubacterium infirmum, Prevotella buccae, and Selenomonas artemidis were detected in the AD group. Interestingly, serum levels of Aβ42, pTau, and anti-P. gingivalis LPS antibody were strongly related to the gene upregulation in human pathogen septicemia.Our study suggested the association of periodontal infection and oral microbiome with AD. Further large-scale studies with longitudinal follow-up are warranted.