THU0008 Hypermethylation of Treg-Specific Demethylated Regions in the Ikaros Transcription Factor Family Members, Helios and EOS, in Rheumatoid Arthritis Tregs. (9th June 2015)

• Record Type: Journal Article
• Authors: Skapenko, A.; Lukas, S.; Haupt, S.; Söntgerath, V.; Leipe, J.; Schulze–Koops, H.
• Is Part Of: Annals of the rheumatic diseases. Volume 74(2015)Supplement 2
• Page Start: 195
• Page End: 195
• Publication Date: 2015-06-09
• Subjects: Rheumatism -- Periodicals; 616.723005
• DOI: 10.1136/annrheumdis-2015-eular.5791
• Languages: English
• ISSNs: 0003-4967

Abstract

Abstract : Background: Members of the Ikaros family of transcription factors have been implicated in controlling the characteristic phenotype of regulatory T cells (Tregs). Ikaros family zinc finger 4 (IKZF4, Eos) mediates Foxp3-dependent gene silencing and is required to maintain the phenotype of Foxp3-positive Tregs, whereas IKFZ2 (Helios) is involved in the suppression of IL2 gene transcription and upregulation of Foxp3. An important regulation level of tissue-specific gene-expression is DNA methylation. In particular, Treg-specific gene expression is controlled by DNA methylation within characteristic clusters, Treg-specific demethylation regions . Objectives: To analyze the DNA methylation status of Treg-specific demethylated regions of Helios and Eos in T cells from patients with rheumatoid arthritis (RA) and to compare the level of methylation to that in T cells from healthy controls. Methods: In both genes, DNA methylation was assessed by bisulfite sequencing in a CpG island located in an intragenic conserved non-coding sequence (CNS). In addition, a CpG-rich region in exon 6 of the Helios gene was also analyzed. Results: All analyzed regions were completely methylated in effector T cells from RA patients and controls. In contrast, considerable degrees of demethylation were detected in the regions of interest in CD25+CD127- T cells, in line with the hypothesis of an important regulatory mechanism facilitating Treg-specific gene expression. Importantly, the methylation rate of the CNS CpG island in the Helios gene was significantly higher in Tregs from RA patients than in those from controls (55% vs. 40%, p<0.05). Similarly, the CpGs within exon 6 of the Helios gene were demethylated to a significantly different level between RA patients and controls (50% vs. 40% methylation, respectively; p<0.05). Finally, in the CNS CpG island of the Eos gene, the methylation level in Tregs from RA patients was also significantly higher as compared to healthy control Tregs (68% vs. 53%, p<0.01). Conclusions: The data are consistent with the hypothesis of Treg specific expression of Helios and Eos regulated by DNA methylation within Treg-specific demethylation regions. Furthermore, the data suggest that impaired function Tregs in RA might be related to an altered expression of Helios and Eos as a consequence of increased DNA methylation. This mechanism might provide a molecular epigenetic insight into the pathogenesis of autoimmune diseases. Disclosure of Interest: None declared