So far the pathomechanism of preeclampsia in pregnancy is focussed on increased circulating levels of soluble fms-like tyrosin kinase-1 (sFLT-1) that neutralizes glomerular VEGF-A expression and prevents its signaling at the glomerular endothelium. As a result of changed glomerular VEGF-A levels endotheliosis and podocyte foot process effacement are typical morphological features of preeclampsia. Recently, microRNA-26a-5p (miR-26a-5p) was described to be also upregulated in the preeclamptic placenta. We found that miR-26a-5p targets VEGF-A expression by means of PIK3C2α in cultured human podocytes and that miR-26a-5p overexpression in zebrafish causes proteinuria, edema, glomerular endotheliosis and podocyte foot process effacement. Interestingly, recombinant zebrafish Vegf-Aa protein could rescue glomerular changes induced by miR-26a-5p. In a small pilot study, preeclamptic patients with podocyte damage identified by podocyturia, expressed significantly more urinary miR-26a-5p compared to healthy controls. Thus, functional and ultrastructural glomerular changes after miR-26a-5p overexpression can resemble the findings seen in preeclampsia and indicate a potential pathophysiological role of miR-26a-5p in addition to sFLT-1 in this disease.

Although several risk factors such as infarct size have been identified, the progression of heart failure (HF) remains difficult to predict in clinical practice. Using an experimental rat model of post-myocardial infarction (MI), we previously identified 45 proteins differentially modulated during HF by proteomic analysis. This study sought to identify microRNAs (miRNAs) able to regulate these proteins and to test their relevance as biomarkers for HF. In silico bioinformatical analysis selected 13 miRNAs related to the 45 proteins previously identified. These miRNAs were analyzed in the rat and in cohorts of patients phenotyped for left ventricular remodeling (LVR). We identified that 3 miRNAs, miR-21-5p, miR-23a-3p and miR-222-3p, and their target Mn superoxide dismutase (SOD2) were significantly increased in LV and plasma of HF-rats. We found by luciferase activity a direct interaction of miR-222-3p with 3'UTR of SOD2. Transfection of human cardiomyocytes with miR-222-3p mimic or inhibitor induced respectively a decrease and an increase of SOD2 expression. Circulating levels of the 3 miRNAs and their target SOD2 were associated with high LVR post-MI in REVE-2 patients. We demonstrated for the first time the potential of microRNAs regulating SOD2 as new circulating biomarkers of HF.

Hypertrophic cardiomyopathy (HCM) is one of the most common hereditary heart diseases and is associated with a high risk of sudden cardiac death. HCM is characterized by pronounced hypertrophy of cardiomyocytes, fiber disarray and development of fibrosis and can be divided into a non-obstructive (HNCM) and obstructive form (HOCM) therefore requiring personalized therapeutic therapies. In the present study, we investigated the expression patterns of several circulating circular RNAs (circRNAs) as potential biomarkers in patients with HCM. We included 64 patients with HCM and 53 healthy controls to the study and quantitatively measured the expression of a set of circRNAs already known to be associated with cardiac diseases (circDNAJC6) and/or being highly abundant in blood (circTMEM56 and circMBOAT2). Abundancy of circRNAs was then correlated to relevant clinical parameters. Serum expression levels of circRNAs DNAJC6, TMEM56 and MBOAT2 were downregulated in patients with HCM. The inverse association between circRNA levels and HCM remained unchanged even after adjusting for confounding factors. All circRNAs, evaluated separately or in combination, showed a robust discrimination capacity when comparing control subjects with HCM, HNCM or HOCM patients (AUC from 0.722 to 0.949). Two circRNAs, circTMEM56 and circDNAJC6, significantly negatively correlated with echocardiographic parameters for HOCM. Collectively, circulating circRNAs DNAJC6, TMEM56 and MBOAT2 can distinguish between healthy and HCM patients. In addition, circTMEM56 and circDNAJC6 could serve as indicators of disease severity in patients with HOCM. Thus, circRNAs emerge as novel biomarkers for HCM facilitating the clinical decision making in a personalized manner.

Hypertrophic cardiomyopathy (HCM) is one of the most common hereditary heart diseases and can be classified into an obstructive (HOCM) and non-obstructive (HNCM) form. Major characteristics for HCM are the hypertrophy of cardiomyocytes and development of cardiac fibrosis. Patients with HCM have a higher risk for sudden cardiac death compared to a healthy population. In the present study, we investigated the abundancy of selected proteins as potential biomarkers in patients with HCM. We included 60 patients with HCM and 28 healthy controls and quantitatively measured the rate of a set of 92 proteins already known to be associated with cardiometabolic processes via protein screening using the proximity extension assay technology in a subgroup of these patients (20 HCM and 10 healthy controls). After validation of four hits in the whole cohort of patients consisting of 88 individuals (60 HCM patients, 28 healthy controls) we found only one candidate, c-KIT, which was regulated significantly different between HCM patients and healthy controls and thus was chosen for further analyses. c-KIT is a tyrosine-protein kinase acting as receptor for the stem cell factor and activating several pathways essential for cell proliferation and survival, hematopoiesis, gametogenesis and melanogenesis. Serum protein levels of c-KIT were significantly lower in patients with HCM than in healthy controls, even after adjusting for confounding factors age and sex. In addition, c-KIT levels in human cardiac tissue of patients with HOCM were significant higher compared to controls indicating high levels of c-KIT in fibrotic myocardium. Furthermore, c-KIT concentration in serum significantly correlated with left ventricular end-diastolic diameter in HOCM, but not HCM patients. The present data suggest c-KIT as a novel biomarker differentiating between patients with HCM and healthy population and might provide further functional insights into fibrosis-related processes of HOCM.

The family of RNA-binding proteins (RBP) functions as a crucial regulator of multiple biological processes and diseases. However, RBP function in the clinical setting of idiopathic pulmonary fibrosis (IPF) is still unknown. We developed a practical in silico screening approach for the characterization of RBPs using multi-sources data information and comparative molecular network bioinformatics followed by wet-lab validation studies. Data mining of bulk RNA-Sequencing data of tissues of patients with IPF identified Quaking (QKI) as a significant downregulated RBP. Cell-type specific expression was confirmed by single-cell RNA-Sequencing analysis of IPF patient data. We systematically analyzed the molecular interaction network around QKI and its functional interplay with microRNAs (miRs) in human lung fibroblasts and discovered a novel regulatory miR-506-QKI axis contributing to the pathogenesis of IPF. The in silico results were validated by in-house experiments applying model systems of miR and lung biology. This study supports an understanding of the intrinsic molecular mechanisms of IPF regulated by the miR-506-QKI axis. Initially applied to human lung disease, the herein presented integrative in silico data mining approach can be adapted to other disease entities, underlining its practical relevance in RBP research.