Circulating miRNA expression profiling in primary aldosteronism

Introduction: Primary aldosteronism (PA) is a major cause of secondary hypertension. The two principal forms of PA are bilateral adrenal hyperplasia (BAH) and aldosterone-producing adenoma (APA) whose differentiation is clinically pivotal, due to their different treatments. Adrenal venous sampling (AVS) is considered to be the gold standard for the differentiation of the two clinical entities, but it is invasive, requires great expertise and is unavailable in many centers. There would be a major clinical need for a reliable and easily accessible diagnostic biomarker. Circulating microRNA were shown to be useful as minimally invasive diagnostic markers in many diseases, but their potential applicability in PA has not yet been investigated. Aims: To determine and compare the circulating microRNA expression profiles of AVS-confirmed APA and BAH plasma samples, and to evaluate their applicability as minimally invasive markers. Methods: 81 AVS-confirmed plasma samples were included. Next-generation sequencing (NGS) was performed on 30 EDTA-anticoagulated plasma samples. Significantly differently expressed miRNAs were validated by real-time RT-qPCR on all samples. Results: We have found relative overexpression of miR-30e-5p, miR-30d-5p, miR-223-3p and miR-7-5p in BAH compared to APA by NGS. Validation of 81 samples confirmed significant overexpression (p=0.03) of miR-7-5p. Regarding the microRNA expressional variations, APA is more heterogenous at the miRNA level compared to BAH. Conclusion: miR-7-5p was significantly overexpressed in BAH samples compared to APA samples, but its sensitivity and specificity values are not good enough for introduction to the clinical practice yet. Altogether 30 samples were investigated by high-throughput miRNA expression profiling (16 aldosterone-producing adenomas and 14 bilateral adrenal hyperplasias)