Background: Epidemiologic studies demonstrated an association between periodontitis (PE) and coronary heart disease (CHD). The coexistence of the two disease entities could be dependent on mutual risk factors, and polymorphism of the interleukin (IL)-1 gene cluster associated with the severity of PE might also be involved in the pathogenesis of CHD.
Methods: The study consisted of 225 dentate white subjects, including 97 patients with CHD and 128 controls. Patients with confirmed diagnoses of CHD were recruited after being discharged from a cardiology department, and controls without CHD were recruited consecutively from the Copenhagen City Heart Study. Mean alveolar bone level (ABL) was measured on radiographs. ABL was stratified into ABL1 (ABL < or = 2 mm), ABL2 (2 mm <ABL < or = 4 mm), and ABL3 (ABL >4 mm). Genotypes were analyzed by amplifying the polymorphic regions of the IL-1 gene cluster using polymerase chain reaction, followed by restriction digestion and gel electrophoresis.
Results: In the univariate analysis, allele 2 of IL-1B+3954 and IL-1B-511 was associated with ABL (P = 0.040 and P = 0.039, respectively), whereas no association was found with allele 2 of IL-1A+4845 or IL-1RN variable number tandem repeat (VNTR) (P = 0.445 and P = 0.375, respectively). A lower ABL was associated with the occurrence of allele 2 of IL-1B-511. The multiple logistic regression analysis also showed a significant association of allele 1 of IL-1B-511 with high ABL (P = 0.049) and of allele 2 of IL-1A+4845 with high ABL among individuals with CHD (P = 0.050). There was no association between any of the polymorphisms of IL-1 and CHD in the univariate or multiple analyses. However, in a binary multiple logistic regression model, carriage of allele 1 of IL-1RN VNTR was found to be associated with the occurrence of both CHD and ABL3 (P = 0.016).
Conclusion: Allele 1 of IL-1RN VNTR may be associated with the coexistence of CHD and PE in a multiple regression model.