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BACKGROUND: Systemic defects in intestinal iron absorption, circulation, and retention cause iron deficiency in 50% of patients with heart failure. Defective subcellular iron uptake mechanisms that are independent of systemic absorption are incompletely understood. The main intracellular route for iron uptake in cardiomyocytes is clathrin-mediated endocytosis. METHODS: We investigated subcellular iron uptake mechanisms in patient-derived and CRISPR/Cas-edited induced pluripotent stem cell-derived cardiomyocytes as well as patient-derived heart tissue. We used an integrated platform of DIA-MA (mass spectrometry data-independent acquisition)-based proteomics and signaling pathway interrogation. We employed a genetic induced pluripotent stem cell model of 2 inherited mutations (TnT [troponin T]-R141W and TPM1 [tropomyosin 1]-L185F) that lead to dilated cardiomyopathy (DCM), a frequent cause of heart failure, to study the underlying molecular dysfunctions of DCM mutations. RESULTS: We identified a druggable molecular pathomechanism of impaired subcellular iron deficiency that is independent of systemic iron metabolism. Clathrin-mediated endocytosis defects as well as impaired endosome distribution and cargo transfer were identified as a basis for subcellular iron deficiency in DCM-induced pluripotent stem cell-derived cardiomyocytes. The clathrin-mediated endocytosis defects were also confirmed in the hearts of patients with DCM with end-stage heart failure. Correction of the TPM1-L185F mutation in DCM patient-derived induced pluripotent stem cells, treatment with a peptide, Rho activator II, or iron supplementation rescued the molecular disease pathway and recovered contractility. Phenocopying the effects of the TPM1-L185F mutation into WT induced pluripotent stem cell-derived cardiomyocytes could be ameliorated by iron supplementation. CONCLUSIONS: Our findings suggest that impaired endocytosis and cargo transport resulting in subcellular iron deficiency could be a relevant pathomechanism for patients with DCM carrying inherited mutations. Insight into this molecular mechanism may contribute to the development of treatment strategies and risk management in heart failure.

Additional file 1: Fig. S1. db/db mice exhibit increased structural aortic stiffness. Aortic pressure diameter curves from db/db mice vs. +/db controls. *p < 0.05 vs. +/db controls. (n = 5/group)

Background Myocardial fibrosis is a major determinant of outcome in aortic stenosis (AS). Novel fast real-time (RT) cardiovascular magnetic resonance (CMR) mapping techniques allow comprehensive quantification of fibrosis but have not yet been compared against standard techniques and histology. Methods Patients with severe AS underwent CMR before (n = 110) and left ventricular (LV) endomyocardial biopsy (n = 46) at transcatheter aortic valve replacement (TAVR). Midventricular short axis (SAX) native, post-contrast T1 and extracellular volume fraction (ECV) maps were generated using commercially available modified Look-Locker Inversion recovery (MOLLI) (native: 5(3)3, post-contrast: 4(1)3(1)2) and RT single-shot inversion recovery Fast Low-Angle Shot (FLASH) with radial undersampling. Focal late gadolinium enhancement was excluded from T1 and ECV regions of interest. ECV and LV mass were used to calculate LV matrix volumes. Variability and agreements were assessed between RT, MOLLI and histology using intraclass correlation coefficients, coefficients of variation and Bland Altman analyses. Results RT and MOLLI derived ECV were similar for midventricular SAX slice coverage (26.2 vs. 26.5, p = 0.073) and septal region of interest (26.2 vs. 26.5, p = 0.216). MOLLI native T1 time was in median 20 ms longer compared to RT (p 0.91), excellent for post-contrast T1 times (ICC > 0.81) and good for native T1 times (ICC > 0.62). Diffuse collagen volume fraction by biopsies was in median 7.8%. ECV (RT r = 0.345, p = 0.039; MOLLI r = 0.40, p = 0.010) and LV matrix volumes (RT r = 0.45, p = 0.005; MOLLI r = 0.43, p = 0.007) were the only parameters associated with histology. Conclusions RT mapping offers fast and sufficient ECV and LV matrix volume calculation in AS patients. ECV and LV matrix volume represent robust and universally comparable parameters with associations to histologically assessed fibrosis and may emerge as potential targets for clinical decision making. Open-Access-Publikationsfonds 2020

Background Chronic kidney disease (CKD) is an independent risk factor for the development and severity of coronary artery disease (CHD) and endothelial dysfunction. There is an increase in the circulating angiogenesis inhibitors endostatin (END), thrombospondin-2 (TSP), angiopoietin-2 (ANG) and the nitric oxide (NO) inhibitor asymmetric dimethyl arginine (ADMA) in CKD patients. The aim of this study was to evaluate associations of the serum level of these factors and of the related angiogenesis inhibitor, endoglin (ENG), with burden of coronary atherosclerosis. Methods One hundred twenty-two patients undergoing coronary angiography were recruited from the cardiac catheterization lab at a single center. The total burden of coronary plaque (mm2) and the presence of coronary collaterals were quantified using quantitative coronary angiography (QCA). Serum levels of angiogenesis inhibitors were measured by ELISA (ENG, END, and ANG), Luminex assay (TSP), or HLPC (ADMA), respectively. Associations with plaque burden and coronary collateral supply were analyzed in multi-variable linear and logistic regression models. Results There was no significant association found between levels of circulating ADMA, ENG, END, ANG, or TSP and coronary plaque burden or collateral formation. Conclusions Our findings suggest that associations of circulating END, ENG, TSP, and ANG with cardiovascular mortality are unlikely to be mediated via direct effects on coronary plaque formation or by inhibition of collateral formation. Whether associations of these factors with mortality are mediated via local concentrations, myocardial tissue, or intra-plaque expression of these factors or by an effect on plaque vulnerability merits additional investigation. peerReviewed

Based on extensive pre-clinical achievements over the past decades, it appears to be due time for a successful clinical translation in the renal fibrosis field—but what is the quickest road to get there? In light of the recent launch of the Precision Medicine Initiative and success of molecularly informed drugs in oncology, we here discuss what it may take to bring molecularly targeted anti-fibrotic to clinical use in chronic progressive kidney disease. peerReviewed

Diese Arbeit hat zum Ziel, (1) neue (epi)genetische Regulationsmechanismen fur endotheliale Plastizitat zu identifizieren, welche ursachlich zur Organfibrose beitragt und (2) diese (epi)genetischen Regulationsmechanismen und damit Organfibrose therapeutisch zu beeinflussen. Wir konnten relevante epigenetische Veranderungen wahrend der endothelial-mesenchymalen Transition (EndMT, welche eine besondere Form der endothelialen Plastizitat darstellt) im Kontext verschiedener Krankheiten identifizieren und den Einfluss von verschiedenen Auslosefaktoren fur EndMT (wie z.B. Hypoxie oder ein hoher Glucosespiegel) sowie die epigenetischen Veranderungen, die sie induzieren, offenlegen. Zusatzlich haben wir deren Relevanz hinsichtlich der Induktion und Aufrechterhaltung der EndMT untersucht. Weiterhin haben wir EndMT in verschiedenen Stadien untersucht, um genetische Regulationsmechanismen, die das aktive Stadium der Transition steuern, zu identifizieren. Fur das zweite Ziel konnten wir zeigen, dass Serelaxin, eine rekombinante Form des humanen Relaxin-2-Hormons, Herzfibrose zumindest teilweise durch die Inhibition der EndMT reduzieren kann. Auserdem haben wir die Mechanismen betrachtet, welche in den reziproken Zusammenhang zwischen chronischer Nierenerkrankung und Herzfibrose involviert sind und haben microRNAs identifiziert, die moglicherweise als pro-fibrotische Nieren-Herz-Botenstoffe wirken. Ebenfalls konnten wir neue relevante Moglichkeiten und in-vivo Applikationen von CRISPR/Cas-Derivaten identifizieren. Diese Moglichkeit der Genmodulation wirkt gezielt auf epigenetische Modifikationen, welche sowohl Nieren- als auch Herzfibrose reduzieren konnen. Zusammenfassend haben wir in dieser Arbeit gezeigt, dass die endotheliale Plastizitat bei fibroproliferativen Erkrankungen durch epigenetische Modifikationen stark beeinflusst wird (Teil 1). Diese epigenetischen Modifikationen konnten neue therapeutische Angriffspunkte darstellen. Diesbezuglich konnten wir zeigen, dass epigenetische Modifikationen in vivo gezielt verandert und damit Organfibrose reduziert werden kann (Teil 2).