Antibody Responses to Porphyromonas gingivalis Strains in a High-Risk Population

Studies show an association between atherosclerosis and periodontal disease. More recently, elevated antibody titres to periodontal bacteria, which may be strain dependent, have been reported in cardiovascular patients.

Objectives: To examine serum antibody levels to six strains of Porphyromonas gingivalis in patients from a population at high risk for poor oral and general health. Methods: 415 patients from a socio-economically depressed area were enrolled. Detailed medical histories, a periodontal assessment and blood samples were collected. Serum samples were assessed for IgG antibody titres to six strains of P. gingivalis (FDC381, ATCC33277, W50, SPBG, UQD605, Su63) using ELISA. Patients were dichotomized according to antibody levels (≥8000ng/ml=high and <8000 ng/ml=low). Cardiovascular (CV) risk was classified according to the number of classical cardiovascular risk factors for each patient. Results: The average age was 42 (±12) years with 139 (34%) males. High anti-P. gingivalis antibody levels were associated with deepened periodontal probing depths (PPD) (at least 4 sites with probing depths ≥4mm, n=201/415) for all strains examined (p<0.044). In the CV high risk group (n=58), there was no difference in the median antibody levels between those with and without deepened periodontal probing depths. In the CV low risk group (n=41) there was no difference in the median antibody levels to all strains except W50, which was higher in those with deepened PPD (n=20). Conclusions: In this at risk population, high levels of anti-P. gingivalis antibodies were associated with deepened PPD. The association with CV risk was less clear and remains to be determined. This study was supported by NHMRC and Queensland Health.