Evaluation of oxidative stress caused by cariogenic bacteria in dental pulp cell

Caries-causing pathogenic microorganisms (cariogenic microorganisms) are the major source of pulpal inflammation and infection, and they cause the formation of reactive oxygen molecules (ROS) with the cell membrane components they secrete, thus increasing oxidative damage. In this study, the effects of ROS, Glutathione (GSH), Glutathione-S-Transferases (GST), which are the oxidative stress parameters caused by cariogenic microorganisms, and N-acetylcysteine (NAC), an effective antioxidant molecule, on the elimination of oxidative damage in primary cell culture prepared from healthy human dental pulp were investigated. For this purpose, primary cell culture was prepared with healthy dental pulps from wisdom teeth extracted from young individuals. Dental pulp cells in the passageway were incubated with 40 µg/ml lipopolysaccharide (LPS), 40 µg/ml lipoteic acid (LTA) and 0.3 mM hydrogen peroxide (H2O2) alone or with 10 mM pre-incubation. ROS, GSH and GST protein levels and immunohistochemical staining were performed in dental pulp cells. In addition, cell viability and necrosis-apoptosis levels were examined by flow cytometry. Statistical differences between groups were evaluated by Kruskal Wallis analysis followed by Mann-Whitney-U test for pairwise comparisons at =0,05. It was observed that cell viability decreased statistically insignificantly in LPS, LTA and H2O2 applications, and NAC pre-incubation did not cause a significant change (p>0.05). It was observed that NAC preincubation significantly reduced ROS levels in dental pulp cells treated with LPS, LTA and H2O2, both by biochemical analyzes and by immunofluorescence method (p<0.05). Biochemical analysis results showed that LPS, LTA and H2O2 incubation decreased intracellular GSH values of dental pulp cells, while NAC preincubation was insufficient to regenerate intracellular GSH. On the other hand, according to the immunostaining results, NAC+ H2O2 significantly increased intracellular GSH compared to the control (p<0.05). No significant difference was observed between the experimental groups in terms of GST enzyme activity values. As a result, while LPS, LTA and H2O2 affected oxidative stress in dental pulp cells at different levels, although NAC molecule reduced ROS levels, it did not show a significant effect on intracellular GSH levels. Key words: Apoptosis, dental pulp, inflammationon, GSH, GST, oksidative stress, ROS.