Epigenome-wide association study using peripheral blood leukocytes identifies genomic regions associated with periodontal disease and edentulism in the Atherosclerosis Risk in Communities Study

Aim Our goal was to investigate individual susceptibility to periodontitis by conducting an epigenome-wide association study using peripheral blood. Materials and Methods For this analysis, we included 1077 African American and 457 European American participants of the Atherosclerosis Risk in Communities (ARIC) study who had completed a dental examination or reported being edentulous at visit 4 and had available data on DNA methylation. DNA methylation levels were compared by periodontal disease severity and edentulism to identify differentially methylated regions (DMRs) and evaluate the CpGs belonging to those DMRs using multinominal logistic regression. Results We identified a region in gene ZFP57 (6p22.1) that was significantly hypomethylated in severe periodontal disease compared to no/mild periodontal disease in European American participants. A separate region in an unknown gene (located in Chr10: 743,992-744,958) demonstrated significant positive association with edentulism compared to no/mild periodontal disease in African American participants. Four CpGs in a region located within HOXA4 were significantly hypermethylated in severe periodontal disease compared to no/mild periodontal disease in African American participants. Conclusions Our study highlights epigenetic variations in ZPF57 and HOXA4 that were significantly and reproducibly associated with periodontitis. Future studies should evaluate gene regulatory mechanisms in the candidate regions of these loci. Scientific Rationale for Study Without altering the DNA sequence, epigenetic effects (e.g., DNA methylation changes) can alter gene activity and influence host response to periodontal infections. Our well-powered study investigates individual susceptibility to periodontitis by conducting a thorough assessment of periodontitis-related DNA methylation levels in blood. Principal Findings We identified two gene regions, ZPF57 and HOXA4 , that are differentially methylated in individuals with compared to those without periodontitis. Practical implications Studying differential leukocyte DNA methylation patterns may point to candidate regions and underlying gene regulatory mechanisms that play a key role in the progression and/or susceptibility to periodontitis. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement The Atherosclerosis Risk in Communities study has been funded in whole or in part with Federal funds from the National Heart, Lung, and Blood Institute, National Institutes of Health, Department of Health and Human Services, under Contract nos. (HHSN268201700001I, HHSN268201700002I, HHSN268201700003I, HHSN268201700004I, and HHSN268201700005I,). The Dental ARIC Study was supported by the National Institute of Dental and Craniofacial Research (R01 DE11551). Additional support to complete the analysis was provided by the 2018 American Association for Cancer Research (AACR)-Johnson & Johnson Lung Cancer Innovation Science Award (MPIs: Michaud, Platz, and Kelsey). The content of this work is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health. This work was also supported by the Maryland Cigarette Restitution Fund at Johns Hopkins. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: This study reports analyses conducted solely using de-identified data from the ARIC study. The ARIC study protocol was approved by the Institutional Review Boards at each study site. The ARIC participants gave written informed consent. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines and uploaded the relevant EQUATOR Network research reporting checklist(s) and other pertinent material as supplementary files, if applicable. Yes The datasets used in the current study are available from the ARIC study.