RT Journal Article SR Electronic T1 m6A RNA methylation controls salivary gland epithelial cell function and has a protective role in Sjögren’s disease JF Annals of the Rheumatic Diseases JO Ann Rheum Dis FD BMJ Publishing Group Ltd and European League Against Rheumatism SP ard-2024-226224 DO 10.1136/ard-2024-226224 A1 Truffinet, Frederic A1 Arco-Hierves, Alejandro A1 Shalabi, Hosnia A1 Pascaud, Juliette A1 Mazet, Paul A1 Rivière, Elodie A1 E Silva-Saffar, Sacha A1 Fabbri, Lucilla A1 Leboucher, Sophie A1 Besse, Laetitia A1 Messaoudi, Cedric A1 Attina, Aurore A1 David, Alexandre A1 Vagner, Stephan A1 Nocturne, Gaetane A1 Mariette, Xavier A1 Bechara, Rami YR 2024 UL http://ard.bmj.com/content/early/2024/09/24/ard-2024-226224.abstract AB Objectives The RNA epitranscriptomic modification known as N6-methyladenosine (m6A) represents a novel mechanism of gene regulation that is poorly understood in human autoimmune diseases. Our research explores the role of this RNA m6A modification in salivary gland epithelial cells (SGEC) and its impact on the pathogenesis of Sjögren’s disease (SjD).Methods SGECs from SjD patients and controls were analysed for m6A writers METTL3 and METTL14 expression using RNA-seq, quantitative PCR and immunohistochemistry. Functional assays assessed the impact of METTL3 knockdown or pharmacological inhibition on proinflammatory gene expression and immune cell interactions (using transwell and coculture systems). Mechanistic studies examined METTL3-mediated m6A modifications in double-stranded RNA (dsRNA) formation through immunofluorescence. Unsupervised clustering identified patterns of interferon activation in salivary glands and their correlation with m6A writers.Results METTL3 and METTL14 were elevated in SGEC from SjD patients in comparison to controls. Paradoxically, inhibiting METTL3 increased proinflammatory gene expression, enhancing SGEC’s ability to attract immune cells and activate B cells. Conversely, inhibiting the eraser FTO had the opposite effect. METTL3-mediated m6A modifications prevented dsRNA formation and IFN signalling activation. SGEC from SjD showed insufficient METTL3 upregulation compared with controls in response to inflammatory triggers, indicating a limited capacity to regulate the inflammatory response. SjD patients with elevated disease activity and higher interferon signature exhibit reduced METTL3 expression.Conclusions Impairment of m6A modifications in SGEC in response to inflammatory triggers favour the formation of dsRNA, potentially amplifying the interferon loop and contributing to SjD pathogenesis.Data are available in a public, open access repository. Data are available on reasonable request. NS-SV-TT-AC and NS-SV-TT-DC cells are available by MTA from the National Heart, Lung and Blood Institute (NHLBI) and the National Institute of Dental and Craniofacial Research (NIDCR). STM2457, STM2120 and STM3006 are under MTA from STORM THERAPEUTICS LTD. All other reagents are commercially available. RNAseq data generated in this study are available on reasonable request, rami.bechara@universite-paris-saclay.fr. RNAseq data from these studies GSE23117 (48), GSE154926 (49), GSE157159 (50), GSE173808 (51) are publicly available.