Arg‐gingipain, myeloperoxidase, and anti‐CarP across the rheumatoid arthritis spectrum

Periodontitis (PD) and rheumatoid arthritis (RA) are chronic inflammatory diseases that may be linked through immune system activity. Studies suggest RA can begin developing before symptoms appear (preRA), with early immune changes occurring in the body. One possible trigger is the occurrence of myeloperoxidase (MPO)-mediated carbamylation in the inflamed periodontium during the earliest phases of RA, which may precede the occurrence of autoantibodies, particularly anti-carbamylated proteins (anti-CarP). To date, these changes due to PD at different stages of RA have not been studied. This study investigated whether the Porphyromonas gingivalis enzyme, Arg-gingipain (Rgp) is linked to MPO and anti-CarP levels in individuals at different stages of RA. A total of 108 participants were recruited for this study, including preRA, early RA (eRA), established RA (RA), and healthy individuals (nonRA), with and without PD. Periodontal and rheumatological assessments were conducted. Rgp-B gene expressions were analyzed in subgingival plaque, and MPO and anti-CarP levels were measured in saliva and serum samples. Findings revealed that eRA participants with PD had the highest MPO and anti-CarP levels, which strongly correlated with periodontal inflammation. Additionally, MPO and anti-CarP were strongly correlated in all PD groups. These findings suggest that periodontal inflammation, especially in early RA, may contribute to immune responses involved in RA progression.