The anti-citrullinated protein antibody (ACPA), an autoantibody of rheumatoid arthritis (RA), is very specific in the diagnosis of RA and has been detected in early cases and several years before the onset of the disease. In this study, we focused on ACPA and examined whether it could be detected in saliva whether it is associated with periodontal disease.
Porphyromonas gingivalis (Pg) or Escherichia coli (Ec) was administered into the oral cavity of DBA/1JJmsSlc mice. The arthritis index was measured in foot bones, and collected saliva and serum. The amount of ACPA in serum and saliva was measured using ELISA, and antibodies in serum, saliva, and foot bones were detected and analysed by western blotting.
Histopathological analysis of foot bones of the Pg/RA group detected greater inflammatory cell infiltration than in the RA group, and bone resorption was evident. Furthermore, ELISA results show that the amount of ACPA in serum was significantly higher in the Pg/RA group (P < 0.05), with a tendency to also increase in the saliva. In addition, western blotting results show a 55 kDa citrullinated protein in the serum and saliva of the RA and Pg/RA groups.
We conclude that Pg infection increases ACPA in the serum and is reflected in the saliva, and may be involved in the inflammatory progression of RA.