Exposure of Porphyromonas gingivalis to cortisol increases bacterial growth

Psychological stress is considered as a risk factor for periodontal diseases. The stress-related hormone, cortisol is one of the main molecules released during human stress response and is found in plasma and gingival crevicular fluid. This hormone has been suggested to modify composition of subgingival biofilms. The aim of this study was to investigate the effect of exposure to cortisol on Porphyromonas gingivalis (P. gingivalis) growth.

P. gingivalis ATCC strain 33277 was cultured under strict anaerobic conditions at 37°C in Brain Heart Infusion medium supplemented with hemin (5μgml(-1)) and menadione (1μgml(-1)). Bacterial cultures were incubated with or without hydrocortisone (0.04-10μgml(-1)) at 37°C for 12, 24 and 48h and bacterial growth was evaluated by spectrophotometric method (OD600nm). Cortisol consumption has been followed by HPLC.

Cortisol significantly increased P. gingivalis growth in the first 24h peaking at 12h but this increase was not related to the concentration used. During the time period, no consumption of cortisol was observed.

This study provides further support for the idea that stress-induced hormone; cortisol may influence the growth of P. gingivalis. This specific effect may be involved in the relationship between stress and periodontal diseases.