Quantitative Analysis of the Periodontal Pathogens' Behavior Under Succinate Concentrations

Objectives: Many scientific studies have shown that there is a strong two-way association between diabetes mellitus and oral health, especially regarding periodontal diseases. From the previous studies in our lab, we have identified an increase in the growth of periodontal pathogens under high glucose concentrations. However, the underlying exact mechanism behind these trends still remained unclear. Recently, several studies have detected an elevated level of succinate in diabetic patients as well as patients with periodontitis. The succinate is one of intermediate compounds in the tricarboxylic acid (TCA) cycle, which is one of the byproducts derived from a step wise cyclic process in order to oxidize the pyruvate formed during the glycolytic breakdown of glucose. Furthermore, some studies have suggested that some identified periodontal pathogens utilize the succinate as a source of energy for their growth. Accordingly, the aim of our study was to uncover the mechanism behind this two-way relationship by focusing on the periodontal pathogens, Porphyromonas gingivalis and Fusobacterium nucleatum, which are associated with periodontitis under the various concentrations of succinate.
Methods: We analyzed the bacterial growth and their behavior in several different levels of succinate (0, 0.1, 0.5, 1, 5, 10 mg/ml) by using the optical density (OD) measurements and the plate count method. In addition, their virulence under different concentrations of succinate was measured by PCR.
Results: So far, the CFU plate count from Day 0, Day 3, and Day 7 shows the increasing trend of the pathogenic growth as the succinate concentration increases. The results indicated that the hyper-succinate condition could promote the growth of periodontal bacteria and might alter the degree of their virulence.
Conclusions: These findings will provide healthcare practitioners with a new perspective on a close relationship between oral health and systemic health.