Identification of immunoreactive epitopes of the Porphyromonas gingivalis heat shock protein in periodontitis and atherosclerosis

Abstract

Heat shock protein 60 (HSP60) of Porphyromonas gingivalis, a major periodontal pathogen, might be a trigger molecule linking infectious periodontitis and autoimmune atherosclerosis. The aim of this study was to identify the peptide specificity of anti-P. gingivalis HSP60 monoclonal antibodies and their cross-reactivity with bacterial and human HSPs. Their specific immunoreactivity to periodontal or atherosclerotic lesions was also investigated. Twenty patients with chronic periodontitis and 20 atherosclerosis patients who had undergone surgical intervention for atheromatous plaques with evidence of ongoing periodontal disease, were selected. Synthetic peptide 19 ((TLVVNRLRGSLKICAVKAPG)-specific T-cell lines were established from inflamed gingiva and atheromatous plaque and the phenotypes and cytokine profiles were characterized. Thirty per cent of periodontitis patients and 100% of atherosclerosis patients reacted positively to cross-reactive peptide 19 from both P. gingivalis and human HSP60. The peptide 19-specific T-cell lines demonstrated the phenotype characteristic of helper T cells (CD4(+)) but did not express CD25 or FOXP3. The interleukin-10 levels were elevated significantly in the peptide 19 T-cell line. Synthetic peptide 19 of P. gingivalis HSP60 is an immunoreactive epitope in the periodontitis-atherosclerosis axis.