Women's oral microbiome in hyposalivation aging-related and disease

Saliva modulates the environment of the oral biofilm through pH buffer, microbial attachment to the host surfaces, and nutritional source. The ecology of stress occurs when a physical factor has an adverse impact on an ecosystem or its biotic components. Therefore, salivary flow reduction might affect oral-host balance. The leading causes for hyposalivation include disease-associated Sjogren's Syndrome (SS) and menopausal women as aging-associated. However, little is known about the oral microbiome integrated with host salivary factors in hyposalivation. The aim of this study was to characterize the hyposalivation microbiome caused by aging or disease affecting salivary glands in women. We included 50 women older than 40 years old in any menopausal phase. We collected stimulated saliva from 25 women diagnosed with SS (SS) and 25 no-SS (non-SS). The bacterial profile of the patients was obtained by 16S rRNA sequencing. Bioinformatics analysis used machine learning to analyze the cohort's signs, symptoms, and bacterial profile. Salivary estradiol as sex hormone variation levels were determined. We obtained that 79% of SS group, and 52% in the non-SS group had hyposalivation. We found negatively correlated Prevotella-age and Rothia-estradiol in SS group. Using k-medoids cluster analysis, we found two clusters related to Streptococcus-dominant and Prevotella-dominant. Highlight, we found that the cause of the hyposalivation in the study did not explain differences in microbial diversity comparing non-SS and SS groups. Therefore, microbial clusters found in hyposalivation but not related to systemic conditions suggest that changes in the oral environment might underpin host-microbial balance.The salivary microbiome was similar in women with and without SS. However, hyposalivation showed two distinctive clusters associated with bacterial population profiles. Our study suggests that local ecological disturbances might drive the shift in the microbiome.