Aim: Although aberrant DNA methylation has been described in rheumatoid arthritis (RA), no studies have interrogated this epigenetic modification in early disease. Following recent investigations of T and B lymphocytes in established disease, we now characterize in these cell populations genome-wide DNA methylation in treatment-naive patients with early RA.
Patients & methods: HumanMethylation450 BeadChips were used to examine genome-wide DNA methylation in lymphocyte populations from 23 early RA patients and 11 healthy individuals.
Results: Approximately 2000 CpGs in each cell type were differentially methylated in early RA. Clustering analysis identified a novel methylation signature in each cell type (150 sites in T lymphocytes, 113 sites in B lymphocytes) that clustered all patients separately from controls. A subset of sites differentially methylated in early RA displayed similar changes in established disease.
Conclusion: Treatment-naive early RA patients display novel disease-specific DNA methylation aberrations, supporting a potential role for these changes in the development of RA.
Keywords: B lymphocyte; CpG; DNA methylation; Illumina 450K array; T lymphocyte; early rheumatoid arthritis; genome-wide; treatment naive.