Left ventricular remodeling leads to heart failure in mice with cardiac-specific overexpression of VEGF-B167: echocardiography and magnetic resonance imaging study

Contribution of VEGF-B-Induced Endocardial Endothelial Cell Lineage in Physiological Versus Pathological Cardiac Hypertrophy

BACKGROUND

Preclinical studies have shown the therapeutic potential of VEGF-B (vascular endothelial growth factor B) in revascularization of the ischemic myocardium, but the associated cardiac hypertrophy and adverse side effects remain a concern. To understand the importance of endothelial proliferation and migration for the beneficial versus adverse effects of VEGF-B in the heart, we explored the cardiac effects of autocrine versus paracrine VEGF-B expression in transgenic and gene-transduced mice.

METHODS

We used single-cell RNA sequencing to compare cardiac endothelial gene expression in VEGF-B transgenic mouse models. Lineage tracing was used to identify the origin of a VEGF-B-induced novel endothelial cell population and adeno-associated virus-mediated gene delivery to compare the effects of VEGF-B isoforms. Cardiac function was investigated using echocardiography, magnetic resonance imaging, and micro-computed tomography.

RESULTS

Unlike in physiological cardiac hypertrophy driven by a cardiomyocyte-specific VEGF-B transgene (myosin heavy chain alpha-VEGF-B), autocrine VEGF-B expression in cardiac endothelium (aP2 [adipocyte protein 2]-VEGF-B) was associated with septal defects and failure to increase perfused subendocardial capillaries postnatally. Paracrine VEGF-B led to robust proliferation and myocardial migration of a novel cardiac endothelial cell lineage (VEGF-B-induced endothelial cells) of endocardial origin, whereas autocrine VEGF-B increased proliferation of VEGF-B-induced endothelial cells but failed to promote their migration and efficient contribution to myocardial capillaries. The surviving aP2-VEGF-B offspring showed an altered ratio of secreted VEGF-B isoforms and developed massive pathological cardiac hypertrophy with a distinct cardiac vessel pattern. In the normal heart, we found a small VEGF-B-induced endothelial cell population that was only minimally expanded during myocardial infarction but not during physiological cardiac hypertrophy associated with mouse pregnancy.

CONCLUSIONS

Paracrine and autocrine secretions of VEGF-B induce expansion of a specific endocardium-derived endothelial cell population with distinct angiogenic markers. However, autocrine VEGF-B signaling fails to promote VEGF-B-induced endothelial cell migration and contribution to myocardial capillaries, predisposing to septal defects and inducing a mismatch between angiogenesis and myocardial growth, which results in pathological cardiac hypertrophy.

Comprehensive bioinformatics analysis identifies LAPTM5 as a potential blood biomarker for hypertensive patients with left ventricular hypertrophy

Left ventricular hypertrophy (LVH) is a pivotal manifestation of hypertensive organ damage associated with an increased cardiovascular risk. However, early diagnostic biomarkers for assessing LVH in patients with hypertension (HT) remain indefinite. Here, multiple bioinformatics tools combined with an experimental verification strategy were used to identify blood biomarkers for hypertensive LVH. GSE74144 mRNA expression profiles were downloaded from the Gene Expression Omnibus (GEO) database to screen candidate biomarkers, which were used to perform weighted gene co-expression network analysis (WGCNA) and establish the least absolute shrinkage and selection operator (LASSO) regression model, combined with support vector machine-recursive feature elimination (SVM-RFE) algorithms. Finally, the potential blood biomarkers were verified in an animal model. A total of 142 hub genes in peripheral blood leukocytes were identified between HT with LVH and HT without LVH, which were mainly involved in the ATP metabolic process, oxidative phosphorylation, and mitochondrial structure and function. Notably, lysosomal associated transmembrane protein 5 (LAPTM5) was identified as the potential diagnostic marker of hypertensive LVH, which showed strong correlations with diverse marker sets of reactive oxygen species (ROS) and autophagy. RT-PCR validation of blood samples and cardiac magnetic resonance imaging (CMRI) showed that the expression of LAPTM5 was significantly higher in the HT with LVH model than in normal controls, LAPTM5 demonstrated a positive association with the left ventricle wall thickness as well as electrocardiogram (ECG) parameters widths of the QRS complex and QTc interval. In conclusion, LAPTM5 may be a potential biomarker for the diagnosis of LVH in patients with HT, and it can provide new insights for future studies on the occurrence and the molecular mechanisms of hypertensive LVH.

Vascular growth factors as potential new treatment in cardiorenal syndrome in diabetes

BACKGROUND

Cardiorenal syndrome in diabetes is characterised by alterations of the cardiovascular system paralleled by kidney disease with progressive renal function decline. In diabetes, chronic metabolic and haemodynamic perturbations drive endothelial dysfunction, inflammation, oxidative stress and progressive tissue fibrosis which, in turn, lead to heart and renal anatomo-functional damage. In physiology, vascular growth factors have been implicated in vascular homeostasis; their imbalance, in disease setting such as diabetes, leads to vascular dysfunction and cardiorenal damage.

AIMS

To define the role of vascular growth factors and angiopoietins in cardiorenal syndrome.

MATERIAL AND METHODS

We will focus on the two most studied vascular growth factors, vascular endothelial growth factor (VEGF) and angiopoietins (Angpt). The balance and crosstalk between these growth factors are important in organ development and in the maintenance of a healthy vasculature, heart and kidney. The observed alterations in expression/function of these vascular growth factors, as seen in diabetes, are a protective response against external perturbations.

RESULTS

The chronic insults driving diabetes-mediated cardiorenal damage results in a paradoxical situation, whereby the vascular growth factors imbalance becomes a mechanism of disease. Studies have explored the possibility of modulating the expression/action of vascular growth factors to improve disease outcome. Experimental work has been conducted in animals and has been gradually translated in humans.

DISCUSSION

Difficulties have been encountered especially when considering the magnitude, timing and duration of interventions targeting a selective vascular growth factor. Targeting VEGF in cardiovascular disease has been challenging, while modulation of the Angpt system seems more promising.

CONCLUSION

Future studies will establish the translatability of therapies targeting vascular growth factors for heart and kidney disease in patients with diabetes.

Luhong Formula Has a Cardioprotective Effect on Left Ventricular Remodeling in Pressure-Overloaded Rats

Background

Luhong formula (LHF)-a traditional Chinese medicine containing Cervus nippon Temminck, Carthamus tinctorius L., Astragalus membranaceus (Fisch.) Bge. var. mongholicus (Bge.) Hsiao, Codonopsis pilosula (Franch.) Nannf., Cinnamomum cassia Presl, and Lepidium apetalum Willd-is used in the treatment of heart failure, but little is known about its mechanism of action. We have investigated the effects of LHF on antifibrosis.

Methods

Forty-eight SD male rats were randomly assigned into six groups (n = 8), model group, sham-operation group, perindopril group (0.036 mg/ml), LHF high doses (LHF-H, 1.44 g/mL), LHF middle doses (LHF-M, 0.72 g/mL), and LHF low doses (LHF-L, 0.36 g/mL). Except the sham-operation group, the other groups were received an abdominal aorta constriction to establish a model of myocardial hypertrophy. The HW and LVW were measured to calculate the LVW/BW and HW/BW. ELISA was used to detect the serum concentration of BNP. The expressions of eNOS, TGF-β1, caspase-3, VEGF, and VEGFR2 in heart tissues were assessed by western blot analysis. mRNA expressions of eNOS, Col1a1, Col3a1, TGF-β1, VEGF, and VEGFR2 in heart tissues were measured by RT-PCR. The specimens were stained with hematoxylin-eosin (HE) and picrosirius red staining for observing the morphological characteristics and collagen fibers I and III of the myocardium under a light microscope.

Results

LHF significantly lowered the rat's HW/BW and LVM/BW, and the level of BNP in the LHF-treated group compared with the model group. Histopathological and pathomorphological changes of collagen fibers I and III showed that LHF inhibited myocardial fibrosis in heart failure rats. Treatment with LHF upregulated eNOS expression in heart tissue and downregulated Col1a1, Col3a1, TGF-β1, caspase-3, VEGF, and VEGFR2 expression.

Conclusion

LHF can improve left ventricular remodeling in a pressure-overloaded heart failure rat model; this cardiac protective ability may be due to cardiac fibrosis and attenuated apoptosis. Upregulated eNOS expression and downregulated Col1a1, Col3a1, TGF-β1, caspase-3, VEGF, and VEGFR2 expression may play a role in the observed LHF cardioprotective effect.

Susceptibility to Cardiac Arrhythmias and Sympathetic Nerve Growth in VEGF-B Overexpressing Myocardium

VEGF-B gene therapy is a promising proangiogenic treatment for ischemic heart disease, but, unexpectedly, we found that high doses of VEGF-B promote ventricular arrhythmias (VAs). VEGF-B knockout, alpha myosin heavy-chain promoter (αMHC)-VEGF-B transgenic mice, and pigs transduced intramyocardially with adenoviral (Ad)VEGF- B186 were studied. Immunostaining showed a 2-fold increase in the number of nerves per field (76 vs. 39 in controls, p < 0.001) and an abnormal nerve distribution in the hypertrophic hearts of 11- to 20-month-old αMHC-VEGF-B mice. AdVEGF-B186 gene transfer (GT) led to local sprouting of nerve endings in pig myocardium (141 vs. 78 nerves per field in controls, p < 0.05). During dobutamine stress, 60% of the αMHC-VEGF-B hypertrophic mice had arrhythmias as compared to 7% in controls, and 20% of the AdVEGF-B186-transduced pigs and 100% of the combination of AdVEGF-B186- and AdsVEGFR-1-transduced pigs displayed VAs and even ventricular fibrillation. AdVEGF-B186 GT significantly increased the risk of sudden cardiac death in pigs when compared to any other GT with different VEGFs (hazard ratio, 500.5; 95% confidence interval [CI] 46.4-5,396.7; p < 0.0001). In gene expression analysis, VEGF-B induced the upregulation of Nr4a2, ATF6, and MANF in cardiomyocytes, molecules previously linked to nerve growth and differentiation. Thus, high AdVEGF-B186 overexpression induced nerve growth in the adult heart via a VEGFR-1 signaling-independent mechanism, leading to an increased risk of VA and sudden cardiac death.

Vascular endothelial growth factor enhances profibrotic activities through modulation of calcium homeostasis in human atrial fibroblasts

Vascular endothelial growth factor (VEGF), a pivotal activator of angiogenesis and calcium (Ca²⁺) signaling in endothelial cells, was shown to increase collagen production in atrial fibroblasts. In this study, we evaluated whether VEGF may regulate Ca²⁺ homeostasis in atrial fibroblasts and contribute to its profibrogenesis. Migration, and proliferation analyses, patch-clamp assay, Ca²⁺ fluorescence imaging, and western blotting were performed using VEGF-treated (300 pg/mL or 1000 pg/mL) human atrial fibroblasts with or without coadministration of Ethylene glycol tetra-acetic acid (EGTA, 1 mmol/L), or KN93 (a Ca²⁺/calmodulin-dependent protein kinase II [CaMKII] inhibitor, 10 μmol/L). VEGF (1000 pg/mL) increased migration, myofibroblast differentiation, pro-collagen type I, pro-collagen type III production, and phosphorylated VEGF receptor 1 expression of fibroblasts. VEGF (1000 pg/mL) increased the nonselective cation current (I_NSC) of transient receptor potential (TRP) channels and potassium current of intermediate-conductance Ca²⁺-activated K⁺ (K_Ca3.1) channels thereby upregulating Ca²⁺ entry. VEGF upregulated phosphorylated ERK expression. An ERK inhibitor (PD98059, 50 μmol/L) attenuated VEGF-activated I_NSC of TRP channels. The presence of EGTA attenuated the profibrotic effects of VEGF on pro-collagen type I, pro-collagen type III production, myofibroblast differentiation, and migratory capabilities of fibroblasts. VEGF upregulated the expression of phosphorylated CaMKII in fibroblasts, which was attenuated by EGTA. In addition, KN93 reduced VEGF-increased pro-collagen type I, pro-collagen type III production, myofibroblast differentiation, and the migratory capabilities of fibroblasts. In conclusion, we found that VEGF increases atrial fibroblast activity through CaMKII signaling by enhancing Ca²⁺ entry. Our findings provide benchside evidence leading to a potential novel strategy targeting atrial myopathy and arrhythmofibrosis.

Beyond endothelial cells: Vascular endothelial growth factors in heart, vascular anomalies and placenta

Vascular endothelial growth factors regulate vascular and lymphatic growth. Dysregulation of VEGF signaling is connected to many pathological states, including hemangiomas, arteriovenous malformations and placental abnormalities. In heart, VEGF gene transfer induces myocardial angiogenesis. Besides vascular and lymphatic endothelial cells, VEGFs affect multiple other cell types. Understanding VEGF biology and its paracrine signaling properties will offer new targets for novel treatments of several diseases.

Evaluation of the effects of different treatment modalities on angiogenesis in heart failure patients with reduced/mid-range ejection fraction via VEGF and sVEGFR-1

OBJECTIVES

To investigate the clinical significance of VEGF, sVEGFR-1 in heart failure reduced ejection fraction (HFrEF) and heart failure mid-range ejection fraction (HFmrEF) patients. Methods: A total of 104 people consisting of HFrEF and HFmrEF patients (n=54) and healthy (n=50) subjects were included in this comparative cross-sectional study. The study took place in Gulhane Training and Research Hospital, Ankara, Turkey, between  2011 and 2013. Serum VEGF, sVEGFR-1, plasma pro-BNP analysis and transthoracic echocardiography were performed.  Results: The average sVEGFR-1 level of the HFrEF and HFmrEF patients was significantly higher than the control group (0.185±0.122; 0.141±0.120; p=0.013). The average sVEGFR-1 level of the HFrEF and HFmrEF patients using beta-blocker was significantly higher than the HFrEF and HFmrEF patients not using it (p=0.015). There was a significant and positive correlation between sVEGFR-1 and N-terminal pro-brain natriuretic peptide (pro-BNP)  levels in the group with HF (r=0.211, p=0.044). Conclusion: It increases awareness about the role of sVEGFR-1 in HFrEF anf HFmrEF patients and the need for further studies. Beta-blocker may have a negative effect on angiogenesis in HFrEF and HFmrEF via increasing sVEGFR-1 levels. Additionally, Pro-BNP may contribute to inhibiting angiogenesis by increasing sVEGFR-1 levels and sVEGFR-1 may be an important biomarker in HFrEF and HFmrEF.

Getting to the heart of the sphingolipid riddle

Obesity, Type 2 Diabetes, and Metabolic Syndrome induce dyslipidemia resulting in inundation of peripheral organs with fatty acids. These not only serve as substrates for energy production, but also contribute to aberrant production of bioactive lipids. Moreover, lipid metabolism is affected in many cardiac disorders including heart failure, ischemia reperfusion injury, and others. While lipids serve crucial homeostatic roles, perturbing biosynthesis of lipid mediators leads to aberrant cell signaling, which contributes to maladaptive cardiovascular programs. Bioactive sphingolipids, in particular, have been implicated in pathophysiology in the heart and vasculature by a variety of studies in cells, animal models, and humans. Because of the burgeoning interest in sphingolipid-driven biology in the cardiovascular system, it is necessary to discuss the experimental considerations for studying sphingolipid metabolism and signaling, emphasizing the caveats to some widely available experimental tools and approaches. Additionally, there is a growing appreciation for the diversity of ceramide structures generated via specific enzymes and bearing disparate cellular functions. While targeting these individual species and enzymes constitutes a major advance, studies show that sphingolipid synthesis readily adapts to compensate for experimental targeting of any individual pathway, thereby convoluting data interpretation. Furthermore, though some molecular mechanisms of sphingolipid action are known, signaling pathways impacted by sphingolipids remain incompletely understood. In this review, we discuss these issues and highlight recent studies as well as future directions that may extend our understanding of the metabolism and signaling actions of these enigmatic lipids in the cardiovascular context.

Guidelines for measuring cardiac physiology in mice

Cardiovascular disease is a leading cause of death, and translational research is needed to understand better mechanisms whereby the left ventricle responds to injury. Mouse models of heart disease have provided valuable insights into mechanisms that occur during cardiac aging and in response to a variety of pathologies. The assessment of cardiovascular physiological responses to injury or insult is an important and necessary component of this research. With increasing consideration for rigor and reproducibility, the goal of this guidelines review is to provide best-practice information regarding how to measure accurately cardiac physiology in animal models. In this article, we define guidelines for the measurement of cardiac physiology in mice, as the most commonly used animal model in cardiovascular research.

Listen to this article’s corresponding podcast at http://ajpheart.podbean.com/e/guidelines-for-measuring-cardiac-physiology-in-mice/.

Left ventricular remodeling leads to heart failure in mice with cardiac-specific overexpression of VEGF-B167: echocardiography and magnetic resonance imaging study

Cardiac-specific overexpression of vascular endothelial growth factor (VEGF)-B₁₆₇ is known to induce left ventricular hypertrophy due to altered lipid metabolism, in which ceramides accumulate to the heart and cause mitochondrial damage. The aim of this study was to evaluate and compare different imaging methods to find the most sensitive way to diagnose at early stage the progressive left ventricular remodeling leading to heart failure. Echocardiography and cardiovascular magnetic resonance imaging were compared for imaging the hearts of transgenic mice with cardiac-specific overexpression of VEGF-B₁₆₇ and wild-type mice from 5 to 14 months of age at several time points. Disease progression was verified by molecular biology methods and histology. We showed that left ventricular remodeling is already ongoing at the age of 5 months in transgenic mice leading to heart failure by the age of 14 months. Measurements from echocardiography and cardiovascular magnetic resonance imaging revealed similar changes in cardiac structure and function in the transgenic mice. Changes in histology, gene expressions, and electrocardiography supported the progression of left ventricular hypertrophy. Longitudinal relaxation time in rotating frame (T_1ρ ) in cardiovascular magnetic resonance imaging could be suitable for detecting severe fibrosis in the heart. We conclude that cardiac-specific overexpression of VEGF-B₁₆₇ leads to left ventricular remodeling at early age and is a suitable model to study heart failure development with different imaging methods.

Electrophysiological analyses of transgenic mice overexpressing KCNJ8 with S422L mutation in cardiomyocytes

Genetic analysis of KCNJ8 has pointed a mutation (S422L) as a susceptible link to J wave syndrome (JWS). In vitro expression study indicated that the ATP-sensitive K⁺ (K_ATP) channel with the S422L mutation has the gain-of-function with reduced sensitivity to ATP. However, the electrophysiological impact of KCNJ8 has not been elucidated in vivo. Transgenic mouse strains overexpressing KCNJ8 S422L variant (TGmt) or WT (TGWT) in cardiomyocytes have been created to investigate the influence of KCNJ8 in cardiomyocytes and the JWS-related feature of the S422L variant on the cardiac electrophysiology. These TG strains demonstrated distinct changes in the J-ST segment of ECG with marked QT prolongation, which might be ascribed to the action potential prolongation resulting from the reduction of voltage-dependent K⁺ currents in ventricular cells. The pinacidil-induced K_ATP current was decreased in these TG myocytes and no obvious difference between TG and non-TG (WT) myocytes in the ATP sensitivity of the K_ATP channel was observed although the open probability of the K_ATP channels was significantly lower in TG myocytes than WT. These transgenic mouse strains with distinct ECG changes suggested that the S422L mutation in KCNJ8 gene is not a direct cause of JWS.