2022 Volume 65 Issue 1 Pages 47-55
Purpose: It is important to elucidate the relationship between periodontal disease and rheumatoid arthritis (RA). Thus, we investigated the effect of oral infection with Porphyromonas gingivalis on the exacerbation of RA by histopathological and imaging analysis using an RA mouse model.
Methods: In this study, 11-week-old DBA/1J mice were used as RA model mice for collagen-induced arthritis. In the experimental group, 0.1 ml of P. gingivalis (1×109 CFU/ml) suspended in 2.5% carboxymethylcellulose (CMC) was administered directly into the oral cavity of mice every other day. In the control group, 0.1 ml of 2.5% CMC was administered in the same manner. At day 45 after oral administration, mice in both groups were sacrificed, and the left lower limbs and spine were collected and analyzed. Soft X-ray images of the left lower limbs were used to evaluate the development of RA symptoms. The periarticular bone tissue of the spine was evaluated by micro-computed tomography (micro-CT) or histological morphological observation by safranin O/fast green staining. In spinal joints, immunohistochemical staining using matrix metalloproteinase-13 (MMP-13) antibody was performed to detect the type II collagen present in the cartilage.
Results: Soft X-ray showed ankylosis, bone obscuration, and a rough appearance in the experimental group. Micro-CT analysis showed a significant decrease in the interspinous distance in the experimental group. Histological analysis showed a marked decrease in type II collagen in the cartilage endplates. Furthermore, the number of MMP-13-positive cells detected in the cartilage endplates and fibrous rings was 1.6 times higher in the experimental group than in the control group.
Conclusion: Oral infection with P. gingivalis promotes tissue destruction in the spinal joints of the mouse model of collagen-induced arthritis, suggesting that periodontal disease caused by P. gingivalis may have a systemic effect on the progression of symptoms in patients with rheumatoid arthritis.
