hsa-miR-7 Is a Potential Biomarker for Idiopathic Inflammatory Myopathies with Interstitial Lung Disease in Humans

microRNAs (miRNAs) have been identified as biomarkers for various diseases. However, the significance of circulating miRNAs for the diagnosis of idiopathic inflammatory myopathies (IIM) is still unknown. In this study, we aim to investigate the significance of miRNAs as potential biomarkers for predicting the patients with IIM and interstitial lung disease (ILD) METHODS: Total RNA was isolated from plasma of 43 IIM patients and 43 healthy people. The expression of miRNAs was analyzed by miRNA microarray and validated by qRT-PCR RESULTS: Microarray shows more differentially expressed circulating miRNAs found in IIM patients compared with healthy controls (P<0.05). qRT-PCR confirmed miR-7 and miR-21 showes significantly changed levels in plasma samples between IIM patients and healthy controls (P<0.05). However, only miR-7 was the sole miRNA lower expression in each IIM patient (P<0.05), which is also lower expression in IIM/ILD patients than that without ILD (P<0.05). The area under curve (AUC) for distinguishing IIM/ILD patients from IIM without ILD is 0.8978, and the 95% confidence interval is 0.7961 to 0.9995. The receiver operating characteristic (ROC) curve analysis showes miR-7 cutoff value is 0.0063. Further, AUC analysis showes both miR-7 and miR-21 have diagnostic value as biomarkers for IIM patients form health controls; however, miR-7 is more sensitive CONCLUSION: miR-7 is a potential biomarker as a diagnostic indicator for IIM patients and can be used to distinguish IIM/ILD patients from IIM without ILD.