The diagnostic utility of miRNA21 in systemic sclerosis.

Objective: Systemic sclerosis (SSc) is a multisystem autoimmune disease of heterogeneous pathogenesis, including vascular, immunologic, genetic, epigenetic, and environmental factors. Progressive fibrosis is the hallmark of SSc. Intense research has been conducted to unveil new tools for early diagnosis and management, thus reducing morbidity and mortality. miR-21 has recently been considered to play an important role in the fibrosis of SSc. The objective of this study was to evaluate miR-21 levels in SSc patients and study its correlation to the extent of skin fibrosis and association with various clinical characteristics.

Methods: A total of 25 patients with SSc who fulfilled the American College of Rheumatology/European Alliance of Associations for Rheumatology 2013 classification criteria, as well as 25 controls, were enrolled in a cross-sectional study. The extent of skin fibrosis was evaluated using the modified Rodnan skin score, and disease severity was assessed using the Medsger severity score. The levels of miR-21 were measured by quantitative real-time polymerase chain reaction. The 2-ΔΔCt method was used for analysis. SSc patients affected by diabetes mellitus, hypertension, renal impairment, heart disease, malignancy, other autoimmune diseases, or a history of serious acute infection within 6 weeks were excluded.

Results: There was a high statistically significant difference in miR-21 levels between cases and controls (p<0.001). At a cut-off level of 2.55, miR21 could discriminate between SSc patients and controls with sensitivity and specificity. There was no significant correlation between miR-21 levels and the degree of skin fibrosis. There was a significant positive association between miR-21 levels and the presence of arthritis in SSc patients (p=0.007).

Conclusions: miR-21 was suggested as a robust diagnostic biomarker in SSc with exceptional superiority over the traditionally utilized antibodies. Additionally, due to its association with arthritis, it is supposed to play a proinflammatory role in addition to its pronounced profibrotic effects. Interestingly, the profibrotic miR-21 may not reflect the extent of skin fibrosis.