Let-7 Family microRNAs Expression in Subcutaneous Skin Negatively Correlate with Severity of Pulmonary Hypertension in Patients with Systemic Scleroderma

Abstract

Introduction: MicroRNAs (miRNAs) have been shown to play an important role in various cardiovascular diseases. However, its roles in the pathogenesis of connective tissue disease-associated pulmonary hypertension (PH) are not clear. Hypothesis: In patents with systemic scleroderma (SSc), subcutaneous miRNAs expression profiles are different depending on the presence or absence of PH. Methods and Results: Data of 16 SSc patients who underwent subcutaneous tissue biopsy were available for retrospective analysis. To determine the changes in subcutaneous miRNAs expression profiles in SSc-associated PH, a mixture of equal amount of subcutaneous miRNAs from 6 PH or 6 non-PH were prepared. We performed miRNA PCR array analysis, and the miRNA expression was comprehensively compared between PH and non-PH group. We found that 591 miRNAs were upregulated, and 57 miRNAs were downregulated in PH group (Figure). Among them, only miRNAs which showed a Ct value less than 35 were considered for further analysis. When a 1.5-fold difference was considered meaningful, 32 miRNAs were upregulated, and 14 miRNAs were down regulated in PH group. Interestingly, 5 out of 14 downregulated miRNAs belong to let-7 family (let-7a, -7b, -7d, -7f, -7g). We validated the results by quantitative real-time PCR with specific primer for each miRNAs individually and found that 4 let-7 family members (let-7a, -7d, -7f, -7g) were significantly downregulated in 6 PH compared with those in 10 non-PH skin. The expression level of let-7d was negatively correlated with pulmonary arterial pressure measured by echocardiography. Conclusions: The expression level of let-7 family microRNAs in subcutaneous skin are lower in patients with SSc with PH than those without PH. Let-7 family microRNAs expression in subcutaneous skin negatively correlate with severity of PH in patients with SSc. Subcutaneous miRNA could be a useful marker to identify the presence and severity of PH in patients with SSc. ![][1] [1]: /embed/graphic-1.gif