Lars Christian Napp

The miRNA-212/132 family regulates both cardiac hypertrophy and cardiomyocyte autophagy

Pathological growth of cardiomyocytes (hypertrophy) is a major determinant for the development of heart failure, one of the leading medical causes of mortality worldwide. Here we show that the microRNA (miRNA)-212/132 family regulates cardiac hypertrophy and autophagy in cardiomyocytes. Hypertrophic stimuli upregulate cardiomyocyte expression of miR-212 and miR-132, which are both necessary and sufficient to drive the hypertrophic growth of cardiomyocytes. MiR-212/132 null mice are protected from pressure-overload-induced heart failure, whereas cardiomyocyte-specific overexpression of the miR-212/132 family leads to pathological cardiac hypertrophy, heart failure and death in mice. Both miR-212 and miR-132 directly target the anti-hypertrophic and pro-autophagic FoxO3 transcription factor and overexpression of these miRNAs leads to hyperactivation of pro-hypertrophic calcineurin/NFAT signalling and an impaired autophagic response upon starvation. Pharmacological inhibition of miR-132 by antagomir injection rescues cardiac hypertrophy and heart failure in mice, offering a possible therapeutic approach for cardiac failure.

A signature of circulating microRNAs differentiates takotsubo cardiomyopathy from acute myocardial infarction

Aims Takotsubo cardiomyopathy (TTC) remains a potentially life-threatening disease, which is clinically indistinguishable from acute myocardial infarction (MI). Today, no established biomarkers are available for the early diagnosis of TTC and differentiation from MI. MicroRNAs (miRNAs/miRs) emerge as promising sensitive and specific biomarkers for cardiovascular disease. Thus, we sought to identify circulating miRNAs suitable for diagnosis of acute TTC and for distinguishing TTC from acute MI. Methods and results After miRNA profiling, eight miRNAs were selected for verification by real-time quantitative reverse transcription polymerase chain reaction in patients with TTC (n = 36), ST-segment elevation acute myocardial infarction (STEMI, n = 27), and healthy controls (n = 28). We quantitatively confirmed up-regulation of miR-16 and miR-26a in patients with TTC compared with healthy subjects (both, P < 0.001), and up-regulation of miR-16, miR-26a, and let-7f compared with STEMI patients (P < 0.0001, P < 0.05, and P < 0.05, respectively). Consistent with previous publications, cardiac specific miR-1 and miR-133a were up-regulated in STEMI patients compared with healthy controls (both, P < 0.0001). Moreover, miR-133a was substantially increased in patients with STEMI compared with TTC (P < 0.05). A unique signature comprising miR-1, miR-16, miR-26a, and miR-133a differentiated TTC from healthy subjects [area under the curve (AUC) 0.835, 95% CI 0.733–0.937, P < 0.0001] and from STEMI patients (AUC 0.881, 95% CI 0.793–0.968, P < 0.0001). This signature yielded a sensitivity of 74.19% and a specificity of 78.57% for TTC vs. healthy subjects, and a sensitivity of 96.77% and a specificity of 70.37% for TTC vs. STEMI patients. Additionally, we noticed a decrease of the endothelin-1 (ET-1)-regulating miRNA-125a-5p in parallel with a robust increase of ET-1 plasma levels in TTC compared with healthy subjects (P < 0.05). Conclusion The present study for the first time describes a signature of four circulating miRNAs as a robust biomarker to distinguish TTC from STEMI patients. The significant up-regulation of these stress- and depression-related miRNAs suggests a close connection of TTC with neuropsychiatric disorders. Moreover, decreased levels of miRNA125a-5p as well as increased plasma levels of its target ET-1 are in line with the microvascular spasm hypothesis of the TTC pathomechanism.

Happy heart syndrome: role of positive emotional stress in takotsubo syndrome

Abstract Aims Takotsubo syndrome (TTS) is typically provoked by negative stressors such as grief, anger, or fear leading to the popular term ‘broken heart syndrome’. However, the role of positive emotions triggering TTS remains unclear. The aim of the present study was to analyse the prevalence and characteristics of patients with TTS following pleasant events, which are distinct from the stressful or undesirable episodes commonly triggering TTS. Methods and results Takotsubo syndrome patients with preceding pleasant events were compared to those with negative emotional triggers from the International Takotsubo Registry. Of 1750 TTS patients, we identified a total of 485 with a definite emotional trigger. Of these, 4.1% (n = 20) presented with pleasant preceding events and 95.9% (n = 465) with unequivocal negative emotional events associated with TTS. Interestingly, clinical presentation of patients with ‘happy heart syndrome’ was similar to those with the ‘broken heart syndrome’ including symptoms such as chest pain [89.5% (17/19) vs. 90.2% (412/457), P = 1.0]. Similarly, electrocardiographic parameters, laboratory findings, and 1-year outcome did not differ. However, in a post hoc analysis, a disproportionate higher prevalence of midventricular involvement was noted in ‘happy hearts’ compared with ‘broken hearts’ (35.0 vs. 16.3%, P = 0.030). Conclusion Our data illustrate that TTS can be triggered by not only negative but also positive life events. While patient characteristics were similar between groups, the midventricular TTS type was more prevalent among the ‘happy hearts’ than among the ‘broken hearts’. Presumably, despite their distinct nature, happy and sad life events may share similar final common emotional pathways, which can ultimately trigger TTS.

Vascular importance of the miR-212/132 cluster

RATIONALE Many processes in endothelial cells including angiogenic responses are regulated by microRNAs. However, there is limited information available about their complex cross-talk in regulating certain endothelial functions. AIM The objective of this study is to identify endothelial functions of the pro-hypertrophic miR-212/132 cluster and its cross-talk with other microRNAs during development and disease. METHODS AND RESULTS We here show that anti-angiogenic stimulation by transforming growth factor-beta activates the microRNA-212/132 cluster by derepression of their transcriptional co-activator cAMP response element-binding protein (CREB)-binding protein (CBP) which is a novel target of a previously identified pro-angiogenic miRNA miR-30a-3p in endothelial cells. Surprisingly, despite having the same seed-sequence, miR-212 and miR-132 exerted differential effects on endothelial transcriptome regulation and cellular functions with stronger endothelial inhibitory effects caused by miR-212. These differences could be attributed to additional auxiliary binding of miR-212 to its targets. In vivo, deletion of the miR-212/132 cluster increased endothelial vasodilatory function, improved angiogenic responses during postnatal development and in adult mice. CONCLUSION Our results identify (i) a novel miRNA-cross-talk involving miR-30a-3p and miR-212, which led to suppression of important endothelial genes such as GAB1 and SIRT1 finally culminating in impaired endothelial function; and (ii) microRNAs may have different biological roles despite having the same seed sequence.

Ex vivo expanded haematopoietic progenitor cells improve dermal wound healing by paracrine mechanisms

Background:  Although dermal wounds are common, treatment remains limited and largely ineffective. Recent studies suggest that therapeutic application of progenitor cells is useful for tissue regeneration.

Two's company: double-chambered right ventricle[corrected].

A 26-year-old pregnant woman was admitted to the hospital because of premature rupture of the membranes at gestational week 26. She had given birth to a child previously without any problems and denied ever having had symptoms of heart failure. Because a ventricular septal defect had been surgically corrected during childhood and a systolic heart murmur was now present, she was referred for transthoracic echocardiography. The interventricular septum appeared normal and did not show any shunt after ventricular septal defect closure. Significant valve abnormalities could be excluded. …