Increased METTL3 expression and m⁶A RNA methylation may contribute to the development of dry eye in primary Sjogren's syndrome

BackgroundPrimary Sjogren's syndrome (pSS) is a chronic autoimmune disorder defined by xerostomia and keratoconjunctivitis sicca, and its etiology remains unknown. N6-methyladenosine (m(6)A) is the predominant posttranscriptional modification in eukaryotic mRNAs and is dynamically regulated by m(6)A regulators. Dysregulation of m(6)A modification is closely associated with several autoimmune disorders, but the role of m(6)A modification in pSS remains unknown. This study investigated the potential role of m(6)A and m(6)A-related regulators in pSS patients with dry eye.MethodsThis cross-sectional study included forty-eight pSS patients with dry eye and forty healthy controls (HCs). Peripheral blood mononuclear cells (PBMCs) were isolated, and the level of m(6)A in total RNA was measured. The expression of m(6)A regulators was determined utilizing real-time PCR and western blotting. The serological indicators detected included autoantibodies, immunoglobulins (Igs), complement factors (Cs), and inflammatory indicators. Dry eye symptoms and signs were measured, including the ocular surface disease index, Schirmer's test (ST), corneal fluorescein staining score (CFS), and tear break-up time. Spearman's correlation coefficient was employed to assess the associations of m(6)A and m(6)A-related regulator expression with clinical characteristics.ResultsThe expression level of m(6)A was markedly increased in the PBMCs of pSS patients with dry eye compared to HCs (P (value)<0.001). The relative mRNA and protein expression levels of the m(6)A regulators methyltransferase-like 3 (METTL3) and YT521-B homology domains 1 were markedly elevated in pSS patients with dry eye (both P (value)<0.01). The m(6)A RNA level was found to be positively related to METTL3 expression in pSS patients (r = 0.793, P (value)<0.001). Both the m(6)A RNA level and METTL3 mRNA expression correlated with the anti-SSB antibody, IgG, ST, and CFS (all P (values) < 0.05). The m(6)A RNA level was associated with C4 (r = -0.432, P (value) = 0.002), while METTL3 mRNA expression was associated with C3 (r = -0.313, P (value) = 0.030).ConclusionsOur work revealed that the upregulation of m(6)A and METTL3 was associated with the performance of serological indicators and dry eye signs in pSS patients with dry eye. METTL3 may contribute to the pathogenesis of dry eye related to pSS.