Oral Microbiota and Porphyromonas Gingivalis Kgp Genotypes Altered in Parkinson’s Disease with Mild Cognitive Impairment

Abstract Cognitive impairment (CI) is a common complication of the non-motor symptoms in Parkinson’s disease (PD), including PD with mild cognitive impairment (PD-MCI) and PD dementia. Recent studies reported the oral dysbiosis in PD and CI, respectively. Porphyromonas gingivalis ( P. gingivalis ), a pathogen of oral dysbiosis, play an important role in PD, whose lysine-gingipain (Kgp) could lead to AD-type pathologies. No previous study investigated the composition of oral microbiota and role of P. gingivalis in PD-MCI. This study aimed to investigates the differences of oral microbiota composition, P. gingivalis copy number, and Kgp genotypes among PD-MCI, PD with normal cognition(PD-NC) and periodontal status-matched control (PC) groups. The oral bacteria composition, the copy number of P. gingivalis and the Kgp genotypes in gingival crevicular fluid from PD-MCI, PD-NC, and PC were analyzed using 16S ribosomal RNA sequencing, quantitative real-time PCR, and MseⅠ restriction. We found that the structures of oral microbiota in PD-MCI group were significantly different compared to that in PD-NC and PC group. The relative abundances of Prevotella , Lactobacillus , Megasphaera , Atopobium and Howardella were negatively correlated with cognitive score. Moreover, there was a significant difference of Kgp genotypes among the three groups. The predominant Kgp genotypes of P. gingivalis in the PD-MCI group was primarily Kgp Ⅱ, whereas in the PD-NC group was mainly Kgp Ⅰ. The Kgp Ⅱ correlated with lower MMSE and MoCA scores, suggested that PD-CI may be related to Kgp genotypes Ⅱ.