Subgingival microbial profiles in pre- and postmenopausal women: Associations with serum estradiol levels

Background

Subgingival dental plaque is an ecosystem playing a key role in supporting both oral health and systemic health. Menopause-related changes have the potential to disrupt its balance, which is crucial to postmenopausal well-being. Our study explored how circulating estradiol levels correlate with subgingival microbial composition using checkerboard DNA-DNA hybridization in premenopausal and postmenopausal women. We also demonstrated that combining this method with 16S ribosomal RNA (rRNA) sequencing insights remains valuable for examining subgingival ecology.

Methods

We assessed 40 bacterial species in 77 premenopausal and 81 postmenopausal women using checkerboard DNA-DNA hybridization and measured serum estradiol with enzyme-linked immunosorbent assay (ELISA). Women were categorized by subgingival dysbiosis severity using a modified Subgingival Microbial Dysbiosis Index (mSMDI). Six women from each normobiotic and dysbiotic subgroup across premenopausal and postmenopausal women underwent 16S rRNA sequencing analysis.

Results

DNA checkerboard analysis revealed that most observed variability in individual bacterial proportions is associated with periodontitis. Two species, Leptotrichia buccalis and Streptococcus constellatus, exhibited differences related to estradiol levels within the premenopausal group (p = 0.055 and p = 0.009, respectively). 16S rRNA sequencing confirmed the mSMDI's validity in categorizing normobiotic and dysbiotic states. Menopausal status was not associated with a dysbiotic shift in the subgingival microbiome despite significantly more attachment loss in postmenopausal compared to premenopausal women.

Conclusions

Our results indicate that decreased estradiol levels or increased attachment loss during menopause are not associated with changes in species abundance or dysbiotic shifts in women. The mSMDI may be a useful tool for classifying subgingival ecology based on its normobiotic or dysbiotic inclination.

Plain Language Summary

The microorganisms in the oral cavity, particularly those around the teeth and gums, form a complex community known as subgingival plaque. This ecosystem is crucial for maintaining both gum health and systemic health. While disease-related (dysbiotic) subgingival plaque causes gum disease (periodontitis), periodontitis further sustains a dysbiotic subgingival plaque microbial environment. Factors such as hormone levels can potentially influence the balance between health and disease-related subgingival plaque microorganisms. We investigated whether blood estradiol levels in women affect the abundance of specific bacteria in subgingival plaque and whether menopause alters the microbial balance in this community. We found that two bacterial species, Leptotrichia buccalis and Streptococcus constellatus, were positively associated with estradiol levels, but only in premenopausal women. Despite postmenopausal women having more severe periodontitis, their subgingival microbiome did not exhibit more dysbiotic characteristics than that of premenopausal women.