Epigenome-wide association study of rheumatoid arthritis identifies differentially methylated loci in B cells

• Published in: Human molecular genetics Vol. 26; no. 14; pp. 2803 - 2811
• Main Authors: Julià, Antonio, Absher, Devin, López-Lasanta, María, Palau, Nuria, Pluma, Andrea, Waite Jones, Lindsay, Glossop, John R, Farrell, William E, Myers, Richard M, Marsal, Sara
• Format: Journal Article
• Language: English
• Published: England 15.07.2017
• Subjects: Aged; Arthritis, Rheumatoid - genetics; Arthritis, Rheumatoid - metabolism; B-Lymphocytes - metabolism; Case-Control Studies; Cohort Studies; CpG Islands - genetics; DNA Methylation - genetics; Epigenesis, Genetic - genetics; Epigenomics - methods; Female; Genome-Wide Association Study - methods; Humans; Lupus Erythematosus, Systemic - genetics; Male; Middle Aged; Signal Transduction
• ISSN: 0964-6906; 1460-2083
• DOI: 10.1093/hmg/ddx177

Epigenetic regulation of immune cell types could be critical for the development and maintenance of autoimmune diseases like rheumatoid arthritis (RA). B cells are highly relevant in RA, since patients express autoantibodies and depleting this cell type is a successful therapeutic approach. Epigenetic variation, such as DNA methylation, may mediate the pathogenic activity of B cells. In this study, we performed an epigenome-wide association study (EWAS) for RA with three different replication cohorts, to identify disease-specific alterations in DNA methylation in B cells. CpG methylation in isolated B lymphocytes was assayed on the Illumina HumanMethylation450 BeadChip in a discovery cohort of RA patients (N = 50) and controls (N = 75). Differential methylation was observed in 64 CpG sites (q < 0.05). Six biological pathways were also differentially methylated in RA B cells. Analysis in an independent cohort of patients (N = 15) and controls (N = 15) validated the association of 10 CpG sites located on 8 genes CD1C, TNFSF10, PARVG, NID1, DHRS12, ITPK1, ACSF3 and TNFRSF13C, and 2 intergenic regions. Differential methylation at the CBL signaling pathway was replicated. Using an additional case-control cohort (N = 24), the association between RA risk and CpGs cg18972751 at CD1C (P = 2.26 × 10-9) and cg03055671 at TNFSF10 (P = 1.67 × 10-8) genes was further validated. Differential methylation at genes CD1C, TNFSF10, PARVG, NID1, DHRS12, ITPK1, ACSF3, TNFRSF13C and intergenic region chr10p12.31 was replicated in a cohort of systemic lupus erythematosus (SLE) patients (N = 47) and controls (N = 56). Our results highlight genes that may drive the pathogenic activity of B cells in RA and suggest shared methylation patterns with SLE.