Serum protein levels of YKL-40 and plasma miR-214 expression in patients with systemic sclerosis.

Objectives: Systemic sclerosis (SSc) is an autoimmune disease with incompletely revealed etiology and pathophysiology. There are still no specific and reliable biomarkers. Here we examined YKL-40 as a biomarker of inflammation and fibrosis, and suggest a possible mechanism for its regulation.

Methods: Forty female patients with SSc (26 with diffuse cutaneous (dcSSc) and 14 with limited cutaneous SSc (lcSSc)) and 14 healthy female controls were enrolled in this cross-sectional study. Bioinformatic tools identified miR-214 binding site in the 3'-untranslated region (3'UTR) of YKL-40 mRNA. Serum levels of YKL-40 were examined by ELISA, while YKL-40 mRNA and miR-214 was measured by qPCR.

Results: The analysis revealed several microRNAs (miRNAs) targeting YKL-40 mRNA, from which miR-214 was selected. YKL-40 serum levels were significantly higher in patients compared to controls ( = .0042). In contrary, miR-214 expression in plasma of SSc patients was significantly down-regulated compared to controls ( = .0058). Receiver operating characteristic (ROC) and area under the curve (AUC) analysis showed that both serum YKL-40 and plasma miR-214 levels had good capacity to distinguish patients with SSc, dcSSc and lcSSc from healthy subjects.

Conclusion: YKL-40 and miR-214 have different expression profile in SSc. Increased serum levels of YKL-40 could be associated with down-regulation of miR-214 expression in plasma. Both, YKL-40 concentrations and miR-214 plasma fold change values might serve as possible biomarkers in SSc.