Expression and clinical significance of plasma microRNA-155 in patients with primary Sjögren’s disease

Abstract Background This study aimed to investigate the expression profile and clinical relevance of microRNA-155 (miRNA-155) in patients with primary Sjögren’s disease (pSD). Methods We enrolled 75 pSD patients, categorized into untreated (n = 41) and treated (n = 34) subgroups, along with 40 healthy controls. Plasma miRNA-155 levels were quantified using quantitative real-time PCR (qRT-PCR) in a subset of participants (24 pSD patients, 10 controls). Clinical and immunological parameters, including erythrocyte sedimentation rate (ESR), anti-SSB antibodies, and organ involvement, were analyzed for correlations with miRNA-155 expression. Results miRNA-155 expression was significantly downregulated in pSD patients compared to controls (P = 0.001). Treated patients had significantly higher miRNA-155 levels than untreated patients (P = 0.045), although both were lower than controls. Subgroup analyses revealed elevated miRNA-155 levels in patients with higher ESR (P = 0.045), anti-SSB seropositivity (P = 0.001), and Chisholm grade III labial gland pathology (vs. grade IV, P = 0.049). Conversely, patients with interstitial lung disease exhibited reduced miRNA-155 expression (P = 0.007). Positive correlations were observed between miRNA-155 and ESR (r = 0.630, P = 0.001) and IgA levels (r = 0.542, P = 0.009). An exploratory analysis suggested lower baseline miRNA-155 levels may be associated with a greater therapeutic reduction in ESR. Conclusions pSD patients demonstrate significantly decreased plasma miRNA-155 expression. These levels are associated with treatment status, anti-SSB antibody production, pulmonary involvement, and labial gland pathology. miRNA-155 levels are also correlated with systemic inflammation and IgA dysregulation, suggesting its potential as a complex biomarker in pSD pathogenesis and for monitoring disease activity.