Baseline angina burden predicts quality of life and functional improvement in patients with viable myocardium treated for chronic total occlusion.

Chronic total occlusion (CTO) is a common finding in patients with known or suspected coronary artery disease and has a distinctive role in these patients' quality of life. However, there is still a lack of evidence of correct patient selection for percutaneous coronary intervention (PCI). From July 2017 to August 2020, 68 patients with successful PCI of a CTO and previous evidence of viability for PCI by cardiovascular magnetic resonance imaging (CMR) were prospectively included in this single-centre observational study. Of these patients, 62 underwent follow-up CMR, and 56 underwent surveys using the Seattle Angina Questionnaire before PCI and 3, 12 and 24 months after PCI. The CMR results were assessed for volumetric, functional and deformation parameters. From the baseline to the follow-up, there was a significant reduction in the left ventricular volumes (all p < 0.001) and an increase in the left ventricular ejection fraction (57.6 ± 11.6% vs. 60.3 ± 9.4%, p = 0.006). Among the deformation parameters, only the left ventricular radial strain showed significant improvement. The SAQ showed an early improvement that emphasised angina stability and frequency as well as a summary score, which persisted after 24 months. A low SAQ summary score before PCI was the best predictive factor of good clinical improvement thereafter. Improvements in myocardial function and quality of life can be achieved with PCI of a CTO. Patient selection for PCI should be performed primarily among relevantly symptomatic patients when evidence of viability for PCI is present. The SAQ can help guide such patient selection.Trial registration ISRCTN, identifier: ISRCTN33203221. Retrospectively registered on 01.04.2020. https://www.isrctn.com/ISRCTN33203221.

Spen deficiency interferes with Connexin 43 expression and leads to heart failure in zebrafish.

Genome-wide association studies identified Spen as a putative modifier of cardiac function, however, the precise function of Spen in the cardiovascular system is not known yet. Here, we analyzed for the first time the in vivo role of Spen in zebrafish and found that targeted Spen inactivation led to progressive impairment of cardiac function in the zebrafish embryo. In addition to diminished cardiac contractile force, Spen-deficient zebrafish embryos developed bradycardia, atrioventricular block and heart chamber fibrillation. Assessment of cardiac-specific transcriptional profiles identified Connexin 43 (Cx43), a cardiac gap junction protein and crucial regulator of cardiomyocyte-to-cardiomyocyte communication, to be significantly diminished in Spen-deficient zebrafish embryos. Similar to the situation in Spen-deficient embryos, Morpholino-mediated knockdown of cx43 in zebrafish resulted in cardiac contractile dysfunction, bradycardia, atrioventricular block and fibrillation of the cardiac chambers. Furthermore, ectopic overexpression of cx43 in Spen deficient embryos led to the reconstitution of cardiac contractile function and suppression of cardiac arrhythmia. Additionally, sensitizing experiments by simultaneously injecting sub-phenotypic concentrations of spen- and cx43-Morpholinos into zebrafish embryos resulted in pathological supra-additive effects. In summary, our findings highlight a crucial role of Spen in controlling cx43 expression and demonstrate the Spen-Cx43 axis to be a vital regulatory cascade that is indispensable for proper heart function in vivo.

Fibroblast growth factor 8b induces uncoupling protein 1 expression in epididymal white preadipocytes.

The number of brown adipocytes residing within murine white fat depots (brite adipocytes) varies a lot by depot, strain and physiological condition. Several endocrine fibroblast growth factors are implicated in the regulation of brite adipocyte abundance. The family of fibroblast growth factors can be categorized by their site of action into endocrine, paracrine and intracellular peptides. We here screened paracrine fibroblast growth factors for their potential to drive brite adipogenesis in differentiating epididymal white adipocytes and identified fibroblast growth factor 8b to induce uncoupling protein 1 expression, but at the same time to interfere in adipogenesis. In an in vivo trial, fibroblast growth factor 8b released into the epididymal fat depot failed to robustly increase the number of brite adipocytes. The specific action of fibroblast growth factor 8b on the uncoupling protein 1 promoter in cultured epididymal adipocytes provides a model system to dissect specific gene regulatory networks.

Bile acid supplementation decreases body mass gain in C57BL/6J but not 129S6/SvEvTac mice without increasing energy expenditure.

Supplementation of cholate to a high fat diet can protect mice from diet-induced, increased body mass gain. It has been hypothesized that uncoupling protein 1 dependent, non-shivering thermogenesis in brown adipocytes provides the mechanism of increased energy expenditure to counteract excessive energy intake. We scrutinized this conjecture in wildtype mice and mice genetically devoid of a functional uncoupling protein 1 gene (C57BL/6J) as well as mice of the 129S6/SvEvTac strain that, in comparison, display an extraordinary capacity to recruit ectopic brown adipocytes. Protection from diet-induced, increased body mass gain by cholate supplementation was absent in 129S6/SvEvTac mice, a consequence of much lower bile acid absorption and spillover in this strain. Conversely, Ucp1-KO mice did not differ from C57BL/6J wildtype controls in any parameter assessed. Daily energy expenditure and resting metabolic rate of C57BL/6J mice remained unaffected by cholate supplementation. We conclude that protection of mice from diet-induced, increased body mass gain by cholate supplementation depends on the specific genetic background of C57BL/6J mice, does not involve increased energy expenditure and is independent of uncoupling protein 1 dependent non-shivering thermogenesis.

In vivo characterization of human myofibrillar myopathy genes in zebrafish.

Myofibrillar myopathies (MFM) are progressive diseases of human heart and skeletal muscle with a severe impact on life quality and expectancy of affected patients. Although recently several disease genes for myofibrillar myopathies could be identified, today most genetic causes and particularly the associated mechanisms and signaling events that lead from the mutation to the disease phenotype are still mostly unknown. To assess whether the zebrafish is a suitable model system to validate MFM candidate genes using targeted antisense-mediated knock-down strategies, we here specifically inactivated known human MFM disease genes and evaluated the resulting muscular and cardiac phenotypes functionally and structurally. Consistently, targeted ablation of MFM genes in zebrafish led to compromised skeletal muscle function mostly due to myofibrillar degeneration as well as severe heart failure. Similar to what was shown in MFM patients, MFM gene-deficient zebrafish showed pronounced gene-specific phenotypic and structural differences. In summary, our results indicate that the zebrafish is a suitable model to functionally and structurally evaluate novel MFM disease genes in vivo.

Arginine-vasopressin directly promotes a thermogenic and pro-inflammatory adipokine expression profile in brown adipocytes.

Arginine-vasopressin (AVP) - via activation of the hypothalamic-pituitary-adrenal (HPA) axis - may play a role in the regulation of energy homeostasis and related cardiovascular complications. Brown adipose tissue (BAT) - via dissipation of energy in the form of heat - contributes to whole body energy balance. BAT expresses vasopressin receptors. We investigated direct effects of AVP on brown adipose endocrine and metabolic functions. UCP-1 protein expression in differentiated brown adipocytes was induced after acute exposure of adipocytes to AVP. This effect was time-dependent with a maximum increase after 8h. AVP also induced a time- and dose-dependent increase in p38 MAP kinase phosphorylation. Pharmacological inhibition of p38 MAP kinase with SB 202190 abolished the induction of UCP-1 protein expression. Furthermore, while acute AVP treatment enhanced mRNA expression of MCP-1 and IL-6, adiponectin mRNA expression was reduced. Yet, on the level of intracellular glucose uptake, there was no AVP-induced change of adipose insulin-induced glucose uptake. Finally, there was no difference in lipid accumulation between control and AVP-treated cells. Taken together, our data demonstrate direct effects of AVP on thermogenic, inflammatory, and glucoregulatory gene expression in brown adipocytes, thus expanding the hitherto known spectrum of this neuropeptides's biological effects and suggesting a direct adipotropic role as a stress-promoting factor.

Metformin inhibits leptin secretion via a mitogen-activated protein kinase signalling pathway in brown adipocytes.

Metformin is an anti-diabetic drug with anorexigenic properties. The precise cellular mechanisms of its action are not entirely understood. Adipose tissue has recently been recognized as an important endocrine organ that is pivotal for the regulation of insulin resistance and energy homeostasis. Due to its thermogenic capacity brown adipose tissue contributes to the regulation of energy metabolism and is an attractive target tissue for pharmacological approaches to treating insulin resistance and obesity. Leptin is the prototypic adipocyte-derived hormone inducing a negative energy balance. We investigated effects of metformin on adipocyte metabolism, signalling, and leptin secretion in a brown adipocyte model. Metformin acutely stimulated p44/p42 mitogen-activated protein (MAP) kinase in a dose- (3.2-fold at 1 mmol/l, P< 0.05) as well as time-dependent (3.8-fold at 5 min, P< 0.05) manner. This stimulation was highly selective since phosphorylation of intermediates in the stress kinase, janus kinase (JAK)-signal transducer and activator of transcription (STAT), and phosphatidylinositol (PI) 3-kinase signalling pathways such as p38 MAP kinase, STAT3, and Akt was unaltered. Furthermore, chronic metformin treatment for 12 days dose-dependently inhibited leptin secretion by 35% and 75% at 500 mumol/l and 1 mmol/l metformin respectively (P< 0.01). This reduction was not caused by alterations in adipocyte differentiation. Moreover, the impairment in leptin secretion by metformin was reversible within 48 h after removal of the drug. Pharmacological inhibition of p44/p42 MAP kinase prevented the metformin-induced negative effect on leptin secretion. Taken together, our data demonstrate direct acute effects of metformin on adipocyte signalling and endocrine function with robust inhibition of leptin secretion. They suggest a selective molecular mechanism that may contribute to the anorexigenic effect of this antidiabetic compound.