Serum miR-21 and miR-29a expression in systemic sclerosis patients.

Objectives: The aim of our study was to evaluate the expression levels of miR-21 and miR-29a in the serum of systemic sclerosis (SSc) patients and to determine their correlation with clinical and immunological parameters.

Methods: 34 patients fulfilling the ACR/EULAR 2013 classification criteria for SSc were included in the study. miR-21 and miR-29a expression levels in the serum were determined by PCR (SYBR Green technology). 2-ΔΔCt method was used for analysis. 14 healthy donors were used as controls (HCs).

Results: Expression levels of miR-21 were upregulated in the serum of 17 (50.0%) of the patients. The expression of miR-29a was downregulated in 15 (44.12%) of the SSc patients. Receiver operating characteristic (ROC) curve analysis was conducted in order to evaluate the diagnostic accuracy of the expression levels of the studied miRNAs in the serum. Area under the curve (AUC) for miR-21 was 0.634 (95% CI=0.479-0.790), p=0.147 with 64.7% sensitivity and 64.3% specificity. AUC for miR-29a was 0.605 (95% CI=0.420-0.790), with 64.3% sensitivity and 52.9% specificity but without statistical significance (p=0.257). The multimarker analysis of the ROC curves for both miRNAs showed AUC=0.714 (95% CI=0.569-0.860), p=0.021 with 79.4% sensitivity and 42.9% specificity. Levels of miR-29a correlated with the levels of miR-21 in the serum (with Spearman correlation coefficient 0.517, p=0.00017) and with the presence of anti-Scl70 antibodies in the serum (with Spearman correlation coefficient 0.438, p=0.010).

Conclusions: Our data showed a deregulation of miR-21 and miR-29a in the serum of patients with SSc which could suggests their potential role in the disease pathogenesis. Further analysis with higher number of patients is needed to confirm if these miRNAs could be used in the clinical practice as diagnostic biomarkers as well as biomarkers for both disease activity and progression.