FRI0268 Dna demethylation characterizes salivary gland epithelial cells from patients with primary sjögren’s syndrome

• Published in: Annals of the rheumatic diseases Vol. 72; no. Suppl 3; p. A465
• Main Authors: Cornec, D., Thabet, Y., Le Dantec, C., Ghedira, I., Devauchelle-Pensec, V., Renaudineau, Y., Pers, J.-O.
• Format: Journal Article
• Language: English
• Published: London BMJ Publishing Group Ltd and European League Against Rheumatism 01.06.2013; BMJ Publishing Group LTD
• ISSN: 0003-4967; 1468-2060
• DOI: 10.1136/annrheumdis-2013-eular.1395

Background Sjögren’s syndrome (SS) is an autoimmune exocrinopathy characterized by an epithelium injury with dense lymphocytic infiltrates composed of activated T and B cells. Present at the interface of genetic and environmental risk factors, epigenetic modifications are suspected to play a key role in SS. Objectives to characterize DNA methylation in SS. Methods 5 methyl cytosine (5MeCyt) ELISA tested global DNA methylation within long-term culture salivary gland epithelial cells (SGEC) and peripheral blood T and B cells from eight SS patients. DNA methylation/demethylation partners were tested by real time quantitative PCR (DNMT1, DNMT3a/b, PCNA, UHRF1, MBD2, MBD4, and Gadd45-alpha). Immunofluorescence was conducted on labial salivary gland biopsy. Co-culture experiments were performed using the human salivary gland cell line (HSG) and B cells. Results Global DNA methylation was reduced in SGEC from SS patients (5MeCyt: 36.3±3.2% in SS versus 43.1±3.3% in controls, P=0.01), while no differences were observed in T and B cells. SGEC demethylation in SS patients was associated with a 7-fold decrease in DNA methyl transferase (DNMT) 1 and a 1.8-fold increase in Gadd45-alpha expression. The other DNA methylation/demethylation partners tested were not different from controls. Interestingly, SGEC demethylation may be attributed in part to the infiltrating B cells as suspected from the analysis of salivary gland biopsy in SS patients treated with rituximab (anti-CD20). Such hypothesis was confirmed using co-culture experiments with HSG cells and B cells revealing an alteration of the ERK/DNMT1 pathway. Finally, several SGEC genes were overexpressed due to DNA methylation changes including ICAM-1 and human endogenous retrovirus (HERV). Conclusions As a consequence, part of the SGEC dysfunction in SS may be linked to epigenetic modifications and this tissue-specific defect may be ascribed in part to infiltrating B cells, thus opening new therapeutic perspectives in SS. Disclosure of Interest: None Declared