Truffinet Frederic, Arco-Hierves Alejandro, Shalabi Hosnia, Pascaud Juliette, Mazet Paul, Rivière Elodie, E Silva-Saffar Sacha, Fabbri Lucilla, Leboucher Sophie, Besse Laetitia, Messaoudi Cedric, Attina Aurore, David Alexandre, Vagner Stephan, Nocturne Gaetane, Mariette Xavier, Bechara Rami
Université Paris-Saclay, Inserm, CEA, Center for Immunology of Viral, Auto-immune, Hematological and Bacterial diseases (IMVA-HB/IDMIT), Inserm U1184, Le Kremlin-Bicetre, France.
Fondation Arthritis, Neuilly Sur Seine, France.
Ann Rheum Dis. 2024 Sep 25. doi: 10.1136/ard-2024-226224.
The RNA epitranscriptomic modification known as -methyladenosine (mA) represents a novel mechanism of gene regulation that is poorly understood in human autoimmune diseases. Our research explores the role of this RNA mA modification in salivary gland epithelial cells (SGEC) and its impact on the pathogenesis of Sjögren's disease (SjD).
SGECs from SjD patients and controls were analysed for mA writers METTL3 and METTL14 expression using RNA-seq, quantitative PCR and immunohistochemistry. Functional assays assessed the impact of knockdown or pharmacological inhibition on proinflammatory gene expression and immune cell interactions (using transwell and coculture systems). Mechanistic studies examined METTL3-mediated mA modifications in double-stranded RNA (dsRNA) formation through immunofluorescence. Unsupervised clustering identified patterns of interferon activation in salivary glands and their correlation with mA writers.
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 mA modifications prevented dsRNA formation and IFN signalling activation. SGEC from SjD showed insufficient 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 expression.
Impairment of mA modifications in SGEC in response to inflammatory triggers favour the formation of dsRNA, potentially amplifying the interferon loop and contributing to SjD pathogenesis.
被称为N6-甲基腺苷（m6A）的RNA表观转录组修饰代表了一种新的基因调控机制，在人类自身免疫性疾病中人们对此了解甚少。我们的研究探讨了这种RNA m6A修饰在唾液腺上皮细胞（SGEC）中的作用及其对干燥综合征（SjD）发病机制的影响。
使用RNA测序、定量PCR和免疫组织化学分析来自SjD患者和对照的SGEC中m6A写入蛋白METTL3和METTL14的表达。功能测定评估敲低或药物抑制对促炎基因表达和免疫细胞相互作用的影响（使用Transwell和共培养系统）。机制研究通过免疫荧光检查METTL3介导的双链RNA（dsRNA）形成中的m6A修饰。无监督聚类确定了唾液腺中干扰素激活模式及其与m6A写入蛋白的相关性。
与对照相比，SjD患者的SGEC中METTL3和METTL14升高。矛盾的是，抑制METTL3会增加促炎基因表达，增强SGEC吸引免疫细胞和激活B细胞的能力。相反，抑制去甲基化酶FTO则产生相反的效果。METTL3介导的m6A修饰可防止dsRNA形成和IFN信号激活。与对照相比，来自SjD的SGEC对炎症触发的反应显示出不足的上调，表明调节炎症反应的能力有限。疾病活动度升高和干扰素特征较高的SjD患者表现出m6A表达降低。
SGEC中m6A修饰对炎症触发的损伤有利于dsRNA的形成，可能会放大干扰素循环并促成SjD的发病机制。
