The Characteristics Of Regulatory T Cells Distribution In Porphyromonas Gingivalis-infected Atherosclerosis Patients

Porphyromonas gingivalis (P.gingivalis) is the main pathogen of periodontal disease. Increasing evidences shows that periodontal pathogen infection contributes to atherosclerosis (AS) progression. Regulatory T cell (Treg) plays a central role in the control of autoimmune response in AS. However, the relationship between P.gingivalis infection and Treg dysregulation during the development of AS is still unknown. The prevalence of different P.gingivalis FimA genotype in the process is unclear. P.gingivalis infection patients were determined by measuring anti-Pgingivalis lgG antibody. The objective of this study was to analyze the relationship between P.gingivalis infection and Treg reduction/dysfunction to elucidate their role in periodontitis-AS interaction.Part I The distribution of regulatory T cells in Porphyromonas gingivalis-infected atherosclerotic patientsObjective To analyze the distribution of Treg in Pgingivalis-infected AS patients.Materials and Methods40P.gingivalis infected atherosclerosis (Pg-AS).32P.gingivalis infected patients (Pg) and29no P.gingivalis and AS patients (HC) were selected. Peripheral blood mononuclear cells were isolated from venous blood of Pg-AS, Pg and HC groups. PBMCs were incubated with antibodies to human CD25, CD4and FOXP3and examined on a flow cytometry to analyze the frequencies of circulating CD4+CD25+T cells and CD4+CD25+FOXP3+Tregs in total CD4+T cell population. Statistical analysis was performed to determine the difference of CD4+CD25+T cells and CD4+CD25+FOXP3+Tregs population among these three groups. The concentration of plasma TGF-bl was measured by ELISA assay and analyzed with statistical analysis.Results The frequencies of CD4+CD25+T cells were4.27%(1.55-10.95%) in the Pg-AS group,4.85%(1.49-10.80%) in the Pg-infected group, and4.56%(1.30-10.60%) in the HC group. No significant difference was analyzed in peripheral CD4+CD25+T cells among these three groups (p>0.05). However, the frequencies of CD4+CD25+FOXP3+Tregs in CD4+T cells in Pg-AS patients were1.95%(0.67-4.43%), significantly lower than in Pg-infected patients [3.38(1.43-7.10)] and controls [3.14%(0.78-5.40%)]. No significant difference was found between Pg-infected and HC groups. An decreased level of TGF-bl was found in Pg-AS patients compared to those with Pg patients and HC. A strongly positive correlation was detected between the frequency of CD4+CD25+FOXP3+Tregs in CD4+T subsets and plasma TGF-(31concentration (r=0.615,p<0.001).Conclusion The population and function of CD4+CD25+FOXP3+Tregs are decreased in P.gingivalis infected atherosclerotic patients.Part II The relationship between Porphyromonas gingivalis FimA genotype and regulatory T cell distributionObjective To analyze Tregs distribution of atherosclerosis infected with different genotype of P.gingivalis.Materials and Methods Sub-gingival plaque samples were taken from the Pg-AS patients and Pg patients. The genomic DNA of bacteria was isolated from plaque samples. P.gingivalis FimA genotype was determined by PCR method with specific primers. Statistical analysis was performed to determine the relationship between genotype Ⅱ FimA and CD4+CD25+FOXP3+Treg distribution of P.gingivalis infected AS patients.Results Type II P.gingivalis was detected in65%of Pg-AS subjects and in59.4%of Pg subjects. There was no difference between with type II and without type II in Pg group. In Pg-AS group, the frequency of CD4+CD25+FOXP3+T cells was1.82%(0.87-3.78%) with genotype II P.gingivalis infection. It was significantly decreased compared with those without genotype II P.gingivalis infected AS patients [2.65%(1.17-4.43%)](p<0.01).Conclusion Type II FimA is the main genotype in sub-gingival plaque of chronic periodontitis. It may be a predominant genotype in the process of P.gingivalis associated AS.In this study, we examined Tregs distribution and TGF-β1concentration in peripheral blood of P.gingivalis infected AS patients compared with periodontitis patients and health controls. The prevalence of P.gingivalis with different genotype was also analyzed. From the results we can conclude that that P.gingivalis infection reduced Tregs in atherosclerosis patients. P.gingivlias FimA genotype II is the dominant type associated with decreased Treg population.