Autoimmune diseases, including atherosclerosis, diabetes mellitus and rheumatoid arthritis, can be triggered and aggravated by the pathogen-driven antigenic peptide from Porphyromonas gingivalis HSP60. P. gingivalis is the major pathogen of chronic periodontitis, which is a global epidemic prevalent in two-thirds of the adult population. The monoclonal antibody raised against peptide 19 (Pep19: TLVVNRLRGSLKICAVKAPG) from P. gingivalis HSP60 was polyreactive to the human homolog. The aim of this study was to determine if Pep19 from P. gingivalis HSP60 manifests itself as a predominant antigen in infection-triggered autoimmune diseases.
 Pep19 from P. gingivalis HSP60, Mycobacterium tuberculosis HSP60 and Chlamydia pneumoniae HSP60 was synthesized for comparative recognition by the sera from patients with atherosclerosis, type 2 diabetes and rheumatoid arthritis, all with ongoing periodontal disease, and by the sera of a control group of patients with periodontal disease but with no history of atherosclerosis, type 2 diabetes or rheumatoid arthritis.
Of the Pep19 peptides from P. gingivalis HSP60, M. tuberculosis HSP60 and C. pneumoniae HSP60, Pep19 from P. gingivalis HSP60 was the peptide epitope predominantly and most consistently recognized by the serum samples of the four disease groups (chronic periodontitis, atherosclerosis, type 2 diabetes mellitus and rheumatoid arthritis).
Seroreactivity to Pep19 of P. gingivalis HSP60, an oral pathogen, was predominant in patients with autoimmune disease with ongoing periodontal disease.