MicroRNA expression profile in circulating exosomes and plasma of patients with gestational diabetes

Introduction. MicroRNAs are small non-coding RNAs, playing critical roles in modulating gene expression. The deregulation of microRNAs has been observed in gestational diabetes (GDM), highlighting their crucial involvement both in the pathogenic mechanisms of this condition and in the development of its complications. Circulating microRNAs can be packaged into exosomes, and exosome signalling has emerged as a novel mechanism of cell-to-cell communication. Through exosomes, microRNAs are delivered in distant target cells and are able to affect gene expression. Aim. The aim of this study was to explore microRNA expression in circulating exosomes and in plasma obtained from patients with GDM and healthy control subjects in the third trimester of gestation, to potentially elucidate some relevant aspects of GDM pathophysiology and individuate novel potential candidate biomarkers for GDM. Methods. A discovery cohort of plasma samples collected from GDM (n=3, age: 34.7 ± 4.9 years; BMI 27.0 ± 3.7 Kg/m2) and NGT women (n=3, age: 34.3 ± 3.1 years; BMI 26.4 ± 1.1 Kg/m2) was recruited. In addition, a discovery cohort of healthy non-pregnant age- and BMI-matched women (NP, n=5) was used as negative control. The microRNA patterns of expression in exosomes and plasma have been assessed with the innovative technology NanoString nCounter microRNA expression (NanoString Technologies inc., Seattle, WA, USA). Target gene identification and bioinformatics analysis of the differentially expressed microRNAs have been performed with Ingenuity Pathway Analysis (IPA, QIAGEN Redwood City, USA). Results. A specific set of microRNAs resulted to be differentially expressed in exosomes and plasma from GDM patients compared to NGT. Specifically, five exosomal microRNAs were significantly upregulated, while 23 were downregulated in GDM compared to NGT. As for plasma, 4 microRNA were upregulated, while 9 were downregulated in GDM compared to NGT. In addition, two microRNAs, miR-196a-5p and miR-652, resulted to be significantly downregulated in GDM compared both to NGT and NP in exosomes and plasma, respectively, suggesting that their deregulation might hallmark GDM pregnancy. In bioinformatics analysis the major predicted target genes and biological processes of the deregulated microRNAs were associated with insulin resistance, abnormal glucose and lipid metabolism, consistently linked to GDM pathophysiology. Conclusions. GDM might alter microRNA profile in exosomes and plasma, conceivably mirroring the metabolic alterations described in GDM pregnancy. In light of this, exploring circulating microRNA expression might help unravel the molecular events leading to the metabolic alterations observed in GDM.