Plasma microRNAs are associated with acute exacerbation in idiopathic pulmonary fibrosis

Haiyan Min, Shanshan Fan, Shiyu Song, Yi Zhuang, Hui Li, Yongzheng Wu, Hourong Cai, Long Yi, Jinghong Dai, Qian Gao

Acute exacerbation of idiopathic pulmonary fibrosis (AE-IPF) has high short-term mortality with unknown causes. To predict this malignant condition in clinics is challenging. In this study, we aim to demonstrate whether there are miRNAs that differ between AE-IPF and stable IPF, which may be served as reliable biomarker for AE-IPF prediction. Human fibrotic-associated miRNAs arrays were designed to detect miRNAs expression in plasma of 3 AE-IPF patients, 3 Stable-IPF (S-IPF) patients and 3 normal controls (NC). Differentially expressed miRNAs between AE-IPF and S-IPF patients were selected for further analyses. The validation studies were carried out in plasma of 12 AE-IPF patients, 45 S-IPF patients and 51 healthy control subjects. Signaling pathways and cellular processes interacted with validated miRNAs were predicted by DIANA-miRPath. According to the array analysis, 6 miRNAs showed differentiated expression between AE-IPF and S-IPF patients (P < 0.05). In the validation studies, let-7d-5p was decreased in S-IPF and further decreased in AE-IPF, when compared to NC (0.0003 ± 0.0002 vs 0.003 ± 0.002, P < 0.01 and 0.0007 ± 0.0005 vs 0.003 ± 0.002, P < 0.01). While miR-25-3p was obviously decreased in S-IPF (0.0002 ± 0.0001 vs 0.0003 ± 0.0003, P < 0.01) but significantly increased in AE-IP (0.0023 ± 0.002 vs 0.0003 ± 0.0003, P < 0.01). In receiver-operator characteristic (ROC) curve analysis, the areas under the curve (AUCs) of miR-25-3p and let-7d-5p were 0.83 and 0.75, respectively. The sensitivity at fixed specificity of 90% was improved from 50% to 66.7% when the two miRNAs were combined. The functional prediction of miRNAs suggested that the loss of anti-fibrotic capacity and the gain of uncontrolled cell growth may be required in AE-IPF pathogenesis. In conclusion, miR-25-3p and let-7d-5p in plasma were differentially expressed between AE-IPF and S-IPF. A combination of these two miRNAs may be a potential biomarker for AE-IPF from IPF.