Virulence of periodontopathogens Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis: micro-computed tomography and inflammatory cytokine analysis

Abstract

The objective of this study is to determine the difference between A. actinomycetemcomitans and P. gingivalis virulence as the cause of periodontal disease. Thirty male Wistar rats were divided into six groups. Ten rats were induced by 10 ug/mL P. gingivalis lipopolysaccharides (LPS), and the other ten rats were induced by 10 ug/mL crude proteins of A. actinomycetemcomitans. The injection was performed three times for six weeks in the interdental area between the first and the second mandibular right molar by using a 30gauge needle. On the third and seventh days, five rats from each group were decapitated and observed with microcomputed tomography (μ-CT) to determine the severity of alveolar bone resorption. The immunohistochemical method was used to find the expression of macrophage inflammatory cytokines (IL-1β and TNF-α). The ANOVA test was performed to determine the difference among each group. The μ-CT image observation of each group revealed that the severity of alveolar bone resorption was different in each group. In the group that was induced by the crude proteins of A. actinomycetemcomitans, resorption was more advanced than those in the LPS and the control group. A significant increase (p<0.05) was found in IL-1β and TNF-α expressions after induction in both groups on the third and seventh days, with the highest cytokine expression observed on the seventh day. The expressions of IL-1β and TNF-α in the group that was induced by the crude proteins of A. actinomycetemcomitans were significantly higher than those in the LPS group. The crude proteins of A. actinomycetemcomitans showed a greater level of virulence than the P. gingivalis LPS in either alveolar bone resorption or inflammatory cytokine expression.