Effects of chronically increased VEGF-A on the aging heart

Integrated multi-omics approach revealed TTNtv c.13254T>G causing dilated cardiomyopathy in mice

Titin-truncating variant (TTNtv) is the most common genetic cause of dilated cardiomyopathy (DCM). In the previous study, we found a novel heterozygous TTNtv c.13254T>G (p.Tyr4418Ter) associated with DCM, but lacking functional evidence. The purpose of this study is to demonstrate the pathogenicity of TTNtv c.13254T>G. We constructed a mouse model with TTNtv Y4370* on exon 45 by CRISPR/Cas9-mediated genome engineering to imitate the TTNtv. c.13254T>G. Transmission electron microscope (TEM), immunohistochemistry, western blot (WB), Transcriptome sequencing (RNA-seq), and tandem Mass Tag (TMT) proteome analysis were performed on the mutant (KO) and WT mice cardiac tissue. Multi-omics association analysis was performed to observe the damages of cardiac tissue, and changes of inflammatory factors and Titin protein. TEM results showed that TTNtv Y4370* may lead to broken myofibrils, sparse myofilament structure, and broken Z-line and H-zone in many places of cardiac tissue of KO mice. Immunohistochemistry showed a significant increase in cTnT and TNF-α expression level in KO mice cardiac tissue. RNA-seq and TMT proteome enrichment analysis further strengthened that TTNtv Y4370* led to cardiac injury and inflammatory response in KO mice. In summary, TTNtv c.13254T>G contributed to the cardiac injury, inflammatory response and construct alterations in mice, that is TTNtv c.13254T>G may cause DCM in mice. These functional evidence of TTNtv c.13254T>G have important significance for follow-up genetic research of DCM in human.

Mechanisms of adaptive hypertrophic cardiac remodeling in a large animal model of premature ventricular contraction-induced cardiomyopathy

Frequent premature ventricular contractions (PVCs) promoted eccentric cardiac hypertrophy and reduced ejection fraction (EF) in a large animal model of PVC-induced cardiomyopathy (PVC-CM), but the molecular mechanisms and markers of this hypertrophic remodeling remain unexplored. Healthy mongrel canines were implanted with pacemakers to deliver bigeminal PVCs (50% burden with 200-220 ms coupling interval). After 12 weeks, left ventricular (LV) free wall samples were studied from PVC-CM and Sham groups. In addition to reduced LV ejection fraction (LVEF), the PVC-CM group showed larger cardiac myocytes without evident ultrastructural alterations compared to the Sham group. Biochemical markers of pathological hypertrophy, such as store-operated Ca2+ entry, calcineurin/NFAT pathway, β-myosin heavy chain, and skeletal type α-actin were unaltered in the PVC-CM group. In contrast, pro-hypertrophic and antiapoptotic pathways including ERK1/2 and AKT/mTOR were activated and/or overexpressed in the PVC-CM group, which appeared counterbalanced by an overexpression of protein phosphatase 1 and a borderline elevation of the anti-hypertrophic factor atrial natriuretic peptide. Moreover, the potent angiogenic and pro-hypertrophic factor VEGF-A and its receptor VEGFR2 were significantly elevated in the PVC-CM group. In conclusion, a molecular program is in place to keep this structural remodeling associated with frequent PVCs as an adaptive pathological hypertrophy.

Biology and therapeutic targeting of vascular endothelial growth factor A

The formation of new blood vessels, called angiogenesis, is an essential pathophysiological process in which several families of regulators have been implicated. Among these, vascular endothelial growth factor A (VEGFA; also known as VEGF) and its two tyrosine kinase receptors, VEGFR1 and VEGFR2, represent a key signalling pathway mediating physiological angiogenesis and are also major therapeutic targets. VEGFA is a member of the gene family that includes VEGFB, VEGFC, VEGFD and placental growth factor (PLGF). Three decades after its initial isolation and cloning, VEGFA is arguably the most extensively investigated signalling system in angiogenesis. Although many mediators of angiogenesis have been identified, including members of the FGF family, angiopoietins, TGFβ and sphingosine 1-phosphate, all current FDA-approved anti-angiogenic drugs target the VEGF pathway. Anti-VEGF agents are widely used in oncology and, in combination with chemotherapy or immunotherapy, are now the standard of care in multiple malignancies. Anti-VEGF drugs have also revolutionized the treatment of neovascular eye disorders such as age-related macular degeneration and ischaemic retinal disorders. In this Review, we emphasize the molecular, structural and cellular basis of VEGFA action as well as recent findings illustrating unexpected interactions with other pathways and provocative reports on the role of VEGFA in regenerative medicine. We also discuss clinical and translational aspects of VEGFA. Given the crucial role that VEGFA plays in regulating angiogenesis in health and disease, this molecule is largely the focus of this Review.

Efficacy of a growth hormone-releasing hormone agonist in a murine model of cardiometabolic heart failure with preserved ejection fraction

Heart failure (HF) with preserved ejection fraction (HFpEF) represents a major unmet medical need owing to its diverse pathophysiology and lack of effective therapies. Potent synthetic, agonists (MR-356 and MR-409) of growth hormone-releasing hormone (GHRH) improve the phenotype of models of HF with reduced ejection fraction (HFrEF) and in cardiorenal models of HFpEF. Endogenous GHRH exhibits a broad range of regulatory influences in the cardiovascular (CV) system and aging and plays a role in several cardiometabolic conditions including obesity and diabetes. Whether agonists of GHRH can improve the phenotype of cardiometabolic HFpEF remains untested and unknown. Here we tested the hypothesis that MR-356 can mitigate/reverse the cardiometabolic HFpEF phenotype. C57BL6N mice received a high-fat diet (HFD) plus the nitric oxide synthase inhibitor (l-NAME) for 9 wk. After 5 wk of HFD + l-NAME regimen, animals were randomized to receive daily injections of MR-356 or placebo during a 4-wk period. Control animals received no HFD + l-NAME or agonist treatment. Our results showed the unique potential of MR-356 to treat several HFpEF-like features including cardiac hypertrophy, fibrosis, capillary rarefaction, and pulmonary congestion. MR-356 improved cardiac performance by improving diastolic function, global longitudinal strain (GLS), and exercise capacity. Importantly, the increased expression of cardiac pro-brain natriuretic peptide (pro-BNP), inducible nitric oxide synthase (iNOS), and vascular endothelial growth factor-A (VEGF-A) was restored to normal levels suggesting that MR-356 reduced myocardial stress associated with metabolic inflammation in HFpEF. Thus, agonists of GHRH may be an effective therapeutic strategy for the treatment of cardiometabolic HFpEF phenotype.NEW & NOTEWORTHY This randomized study used rigorous hemodynamic tools to test the efficacy of a synthetic GHRH agonist to improve cardiac performance in a cardiometabolic HFpEF. Daily injection of the GHRH agonist, MR-356, reduced the HFpEF-like effects as evidenced by improved diastolic dysfunction, reduced cardiac hypertrophy, fibrosis, and pulmonary congestion. Notably, end-diastolic pressure and end-diastolic pressure-volume relationship were reset to control levels. Moreover, treatment with MR-356 increased exercise capacity and reduced myocardial stress associated with metabolic inflammation in HFpEF.

Integrating UPLC-Q-Exactive Orbitrap/MS, network pharmacology and experimental validation to reveal the potential mechanism of Tibetan medicine Rhodiola granules in improving myocardial ischemia-reperfusion injury

ETHNOPHARMACOLOGY RELEVANCE

Rhodiola granules (RG) is a traditional Tibetan medicine prescription that can be used to improve the symptoms of ischemia and hypoxia in cardiovascular and cerebrovascular diseases. However, there is no report on its use to improve myocardial ischemia/reperfusion (I/R) injury, and its potential active ingredients and mechanism against myocardial ischemia/reperfusion (I/R) injury remain unclear.

AIM OF THE STUDY

This study aimed to reveal the potential bioactive components and underlying pharmacological mechanisms of RG in improving myocardial I/R injury through a comprehensive strategy.

MATERIALS AND METHODS

UPLC-Q-Exactive Orbitrap/MS technology was used to analyze the chemical components of RG, the potential bioactive components and targets were tracked and predicted by the SwissADME and SwissTargetPrediction databases, and the core targets were predicted through the PPI network, as well the functions and pathways were determined by GO and KEGG analysis. In addition, the molecular docking and ligation of the anterior descending coronary artery-induced rat I/R models were experimentally validated.

RESULTS

A total of 37 ingredients were detected from RG, including nine flavones, ten flavonoid glycosides, one glycoside, eight organic acids, four amides, two nucleosides, one amino acid, and two other components. Among them, 15 chemical components, such as salidroside, morin, diosmetin, and gallic acid were identified as key active compounds. Ten core targets, including AKT1, VEGF, PTGS2, and STAT3, were discovered through the analysis of the PPI network constructed from 124 common potential targets. These possible targets were involved in the regulation of oxidative stress and HIF-1/VEGF/PI3K-Akt signaling pathways. Furthermore, molecular docking confirmed that the potential bioactive compounds in RG have good potential binding abilities to AKT1, VEGFA, PTGS2, STAT3, and HIF-1α proteins. Then, the animal experiments showed that RG could significantly improve the cardiac function of I/R rats, reduce the size of myocardial infarction, improve the myocardial structure, and reduce the degree of myocardial fibrosis, inflammatory cell infiltration, and myocardial cell apoptosis rate in I/R rats. In addition, we also found that RG could decrease the concentration of AGE, Ox-LDL, MDA, MPO, XOD, SDH, Ca²⁺, and ROS, and increase the concentration of Trx, TrxR1, SOD, T-AOC, NO, ATP, Na⁺k⁺-ATPase, Ca²⁺-ATPase, and CCO. Moreover, RG could significantly down-regulate the expressions of Bax, Cleaved-caspase3, HIF-1α, and PTGS2, as well up-regulate the expressions of Bcl-2, VEGFA, p-AKT1, and p-STAT3.

CONCLUSION

In summary, we revealed for the first time the potential active ingredients and mechanisms of RG for myocardial I/R injury therapy through a comprehensive research strategy. RG may synergistically improve myocardial I/R injury through anti-inflammatory, regulating energy metabolism, and oxidative stress, improving I/R-induced myocardial apoptosis, which may be related to the HIF-1/VEGF/PI3K-Akt signaling pathway. Our study provides new insights into the clinical application of RG and also provides a reference for the development and mechanism research of other Tibetan medicine compound preparations.

Atherosclerosis and Inflammation: Insights from the Theory of General Pathological Processes

Recent advances have greatly improved our understanding of the molecular mechanisms behind atherosclerosis pathogenesis. However, there is still a need to systematize this data from a general pathology perspective, particularly with regard to atherogenesis patterns in the context of both canonical and non-classical inflammation types. In this review, we analyze various typical phenomena and outcomes of cellular pro-inflammatory stress in atherosclerosis, as well as the role of endothelial dysfunction in local and systemic manifestations of low-grade inflammation. We also present the features of immune mechanisms in the development of productive inflammation in stable and unstable plaques, along with their similarities and differences compared to canonical inflammation. There are numerous factors that act as inducers of the inflammatory process in atherosclerosis, including vascular endothelium aging, metabolic dysfunctions, autoimmune, and in some cases, infectious damage factors. Life-critical complications of atherosclerosis, such as cardiogenic shock and severe strokes, are associated with the development of acute systemic hyperinflammation. Additionally, critical atherosclerotic ischemia of the lower extremities induces paracoagulation and the development of chronic systemic inflammation. Conversely, sepsis, other critical conditions, and severe systemic chronic diseases contribute to atherogenesis. In summary, atherosclerosis can be characterized as an independent form of inflammation, sharing similarities but also having fundamental differences from low-grade inflammation and various variants of canonical inflammation (classic vasculitis).

Coupled myovascular expansion directs cardiac growth and regeneration

Heart regeneration requires multiple cell types to enable cardiomyocyte (CM) proliferation. How these cells interact to create growth niches is unclear. Here, we profile proliferation kinetics of cardiac endothelial cells (CECs) and CMs in the neonatal mouse heart and find that they are spatiotemporally coupled. We show that coupled myovascular expansion during cardiac growth or regeneration is dependent upon VEGF-VEGFR2 signaling, as genetic deletion of Vegfr2 from CECs or inhibition of VEGFA abrogates both CEC and CM proliferation. Repair of cryoinjury displays poor spatial coupling of CEC and CM proliferation. Boosting CEC density after cryoinjury with virus encoding Vegfa enhances regeneration. Using Mendelian randomization, we demonstrate that circulating VEGFA levels are positively linked with human myocardial mass, suggesting that Vegfa can stimulate human cardiac growth. Our work demonstrates the importance of coupled CEC and CM expansion and reveals a myovascular niche that may be therapeutically targeted for heart regeneration.

Metformin Attenuates Cardiac Hypertrophy Via the HIF-1α/PPAR-γ Signaling Pathway in High-Fat Diet Rats

Coronary artery disease (CAD) and cardiac hypertrophy (CH) are two main causes of ischemic heart disease. Acute CAD may lead to left ventricular hypertrophy (LVH). Long-term and sustained CH is harmful and can gradually develop into cardiac insufficiency and heart failure. It is known that metformin (Met) can alleviate CH; however, the molecular mechanism is not fully understood. Herein, we used high-fat diet (HFD) rats and H9c2 cells to induce CH and clarify the potential mechanism of Met on CH. We found that Met treatment significantly decreased the cardiomyocyte size, reduced lactate dehydrogenase (LDH) release, and downregulated the expressions of hypertrophy markers ANP, VEGF-A, and GLUT1 either in vivo or in vitro. Meanwhile, the protein levels of HIF-1α and PPAR-γ were both decreased after Met treatment, and administrations of their agonists, deferoxamine (DFO) or rosiglitazone (Ros), markedly abolished the protective effect of Met on CH. In addition, DFO treatment upregulated the expression of PPAR-γ, whereas Ros treatment did not affect the expression of HIF-1α. In conclusion, Met attenuates CH via the HIF-1α/PPAR-γ signaling pathway.

Human organ rejuvenation by VEGF-A: Lessons from the skin

Transplanting aged human skin onto young SCID/beige mice morphologically rejuvenates the xenotransplants. This is accompanied by angiogenesis, epidermal repigmentation, and substantial improvements in key aging-associated biomarkers, including ß-galactosidase, p16^ink4a, SIRT1, PGC1α, collagen 17A, and MMP1. Angiogenesis- and hypoxia-related pathways, namely, vascular endothelial growth factor A (VEGF-A) and HIF1A, are most up-regulated in rejuvenated human skin. This rejuvenation cascade, which can be prevented by VEGF-A-neutralizing antibodies, appears to be initiated by murine VEGF-A, which then up-regulates VEGF-A expression/secretion within aged human skin. While intradermally injected VEGF-loaded nanoparticles suffice to induce a molecular rejuvenation signature in aged human skin on old mice, VEGF-A treatment improves key aging parameters also in isolated, organ-cultured aged human skin, i.e., in the absence of functional skin vasculature, neural, or murine host inputs. This identifies VEGF-A as the first pharmacologically pliable master pathway for human organ rejuvenation in vivo and demonstrates the potential of our humanized mouse model for clinically relevant aging research.

Fibronectin type III domain-containing 5 improves aging-related cardiac dysfunction in mice

Aging is an important risk factor for cardiovascular diseases, and aging‐related cardiac dysfunction serves as a major determinant of morbidity and mortality in elderly populations. Our previous study has identified fibronectin type III domain‐containing 5 (FNDC5) and its cleaved form, irisin, as the cardioprotectant against doxorubicin‐induced cardiomyopathy. Herein, aging or matched young mice were overexpressed with FNDC5 by adeno‐associated virus serotype 9 (AAV9) vectors, or subcutaneously infused with irisin to uncover the role of FNDC5 in aging‐related cardiac dysfunction. To verify the involvement of nucleotide‐binding oligomerization domain‐like receptor with a pyrin domain 3 (NLRP3) and AMP‐activated protein kinase α (AMPKα), Nlrp3 or Ampkα2 global knockout mice were used. Besides, young mice were injected with AAV9‐FNDC5 and maintained for 12 months to determine the preventive effect of FNDC5. Moreover, neonatal rat cardiomyocytes were stimulated with tumor necrosis factor‐α (TNF‐α) to examine the role of FNDC5 in vitro. We found that FNDC5 was downregulated in aging hearts. Cardiac‐specific overexpression of FNDC5 or irisin infusion significantly suppressed NLRP3 inflammasome and cardiac inflammation, thereby attenuating aging‐related cardiac remodeling and dysfunction. In addition, irisin treatment also inhibited cellular senescence in TNF‐α‐stimulated cardiomyocytes in vitro. Mechanistically, FNDC5 activated AMPKα through blocking the lysosomal degradation of glucagon‐like peptide‐1 receptor. More importantly, FNDC5 gene transfer in early life could delay the onset of cardiac dysfunction during aging process. We prove that FNDC5 improves aging‐related cardiac dysfunction by activating AMPKα, and it might be a promising therapeutic target to support cardiovascular health in elderly populations.

[Patterns of immunological reactions in the pathogenesis of chronic heart failure: review]

The immune system is essential for maintaining the homeostasis. At present, there is convincing evidence for participation of the immune system in the pathogenesis of cardiovascular pathology, including the final step of cardiovascular continuum, heart failure. Objective difficulties in understanding subtle processes of loss of the normal cardiac structure and function are based on the diversity of pathogenetic factors of development and progression of chronic heart failure (CHF) and the involvement of most organs and body systems. Russian and international scientists actively study issues of immune homeostasis, including the efficacy of current immune therapy. At the same time, available reports are largely uncompiled and reflect isolated parts of the immunopathogenesis of cardiovascular diseases. This review focuses on comprehensive elucidation of major patterns of immune processes in the CHF pathogenesis to form an integral view of the problem under study.

Effects of different types of exercise training on angiogenic responses in the left ventricular muscle of aged rats

BACKGROUND

We evaluated angiogenic responses in the left ventricular muscle and aerobic capacity according to exercise type (aerobic, resistance, combined) in aged rats.

METHODS

In total, 24 male Sprague-Dawley rats (100 weeks old) were used. To investigate the effect of regular training, the rats were divided into non-exercise (NE), aerobic exercise (AE), resistance exercise (RE), and combined exercise (CE) groups (six rats per group). Regular training tailored to each exercise type was performed for 8 weeks (five times a week, 1 h per day). After 8 weeks of training, aerobic capacity was evaluated by a treadmill running test. Left ventricular muscle tissue was collected and the protein levels of angiogenesis indicators (eNOS, HIF-1α, PGC-1α, VEGF, FLK-1, Ang-1, Ang-2) were analyzed by Western blotting. Capillaries were observed by immunohistochemical staining for CD31.

RESULTS

Body weight, heart weight, and heart/body weight ratio showed no difference among the groups. The AE and CE groups showed higher treadmill running capacity than the NE and RE groups. The eNOS, VEGF, HIF-1α, PGC-1α, and Ang-2 protein levels were significantly higher in the AE than NE group. The PGC-1α and FLK-1 protein levels were significantly higher in the RE than NE group. In addition, in the CE group, the eNOS, FLK-1, and PGC-1α protein levels were significantly higher than in the NE group. Expression of CD31 in cardiac tissue was higher in the AE and CE groups than in the other groups.

CONCLUSIONS

Taken together, the results suggest that regular exercise training, irrespective of exercise type, might improve cardiovascular function by inducing angiogenic responses in the aged myocardium; however, AE may be the most effective.

A bioinformatics approach for identifying potential molecular mechanisms and key genes involved in COVID-19 associated cardiac remodeling

In 2019 coronavirus disease (COVID-19), whose main complication is respiratory involvement, different organs may also be affected in severe cases. However, COVID-19 associated cardiovascular manifestations are limited at present. The main purpose of this study was to identify potential candidate genes involved in COVID-19-associated heart damage by bioinformatics analysis. Differently expressed genes (DEGs) were identified using transcriptome profiles (GSE150392 and GSE4172) downloaded from the GEO database. After gene and pathway enrichment analyses, PPI network visualization, module analyses, and hub gene extraction were performed using Cytoscape software. A total of 228 (136 up and 92 downregulated) overlapping DEGs were identified at these two microarray datasets. Finally, the top hub genes (FGF2, JUN, TLR4, and VEGFA) were screened out as the critical genes among the DEGs from the PPI network. Identification of critical genes and mechanisms in any disease can lead us to better diagnosis and targeted therapy. Our findings identified core genes shared by inflammatory cardiomyopathy and SARS-CoV-2. The findings of the current study support the idea that these key genes can be used in understanding and managing the long-term cardiovascular effects of COVID-19.

Identification of genes associated with sudden cardiac death: a network- and pathway-based approach

Background

Sudden cardiac death (SCD) accounts for a large proportion of the total deaths across different age groups. Although numerous candidate genes related to SCD have been identified by genetic association studies and genome wide association studies (GWAS), the molecular mechanisms underlying SCD are still unclear, and the biological functions and interactions of these genes remain obscure. To clarify this issue, we performed a comprehensive and systematic analysis of SCD-related genes by a network and pathway-based approach.

Methods

By screening the publications deposited in the PubMed and Gene-Cloud Biotechnology Information (GCBI) databases, we collected the genes genetically associated with SCD, which were referred to as the SCD-related gene set (SCDgset). To analyze the biological processes and biochemical pathways of the SCD-related genes, functional analysis was performed. To explore interlinks and interactions of the enriched pathways, pathway crosstalk analysis was implemented. To construct SCD-specific molecular networks, Markov cluster algorithm and Steiner minimal tree algorithm were employed.

Results

We collected 257 genes that were reported to be associated with SCD and summarized them in the SCDgset. Most of the biological processes and biochemical pathways were related to heart diseases, while some of the biological functions may be noncardiac causes of SCD. The enriched pathways could be roughly grouped into two modules. One module was related to calcium signaling pathway and the other was related to MAPK pathway. Moreover, two different SCD-specific molecular networks were inferred, and 23 novel genes potentially associated with SCD were also identified.

Conclusions

In summary, by means of a network and pathway-based methodology, we explored the pathogenetic mechanism underlying SCD. Our results provide valuable information in understanding the pathogenesis of SCD and include novel biomarkers for diagnosing potential patients with heart diseases; these may help in reducing the corresponding risks and even aid in preventing SCD.

VEGF Contributes to Mesenchymal Stem Cell-Mediated Reversion of Nor1-Dependent Hypertrophy in iPS Cell-Derived Cardiomyocytes

Myocardial hypertrophy is present in many heart diseases, representing a strong predictor of adverse cardiovascular outcomes. Regarding therapeutic intervention, mesenchymal stem cells (MSCs) have been suggested to significantly reduce cardiac hypertrophy and progression to heart failure. Preconditioning of MSCs was previously demonstrated to highly improve their paracrine activity resulting in modulation of immune responses and the progression of diseases. Here, we studied the effects of bone marrow-derived preconditioned MSCs on hypertrophied induced pluripotent stem cell-derived cardiomyocytes (iPS-CM) and also sought to identify MSC-derived antihypertrophic molecules. Phenylephrine (PE) was used to induce hypertrophy in murine iPS-CM, and markers of hypertrophy were identified by microarray analysis. Murine MSCs were treated with IFN-γ and IL-1β to enhance their paracrine activity, and transcriptional profiling was performed by microarray analysis. Hypertrophied iPS-CM were subsequently cocultured with preconditioned MSCs or MSC-conditioned medium (CM), respectively. Effects on hypertrophied iPS-CM were studied by cell area quantification, real-time PCR, and western blot. In some experiments, cells were incubated with fractions of MSC-CM obtained by ultrafiltration or by MSC-CM supplemented with inhibitory antibodies. Intracellular and extracellular levels of vascular endothelial growth factor (VEGF) were evaluated by western blot and ELISA. PE-induced hypertrophy in iPS-CM was associated with an upregulation of neuron-derived orphan receptor (Nor1) expression, activation of Akt, and inhibition of both strongly prevented hypertrophy induction in iPS-CM. VEGF secreted by preconditioned MSCs provoked hypertrophy regression in iPS-CM, and a negative correlation between Nor1 expression and hypertrophic growth could be evidenced. Our results demonstrate that Nor1 expression strongly supports hypertrophy in iPS-CM. Moreover, the secretome of preconditioned MSCs triggered regression of hypertrophy in iPS-CM in a VEGF-dependent manner. We suggest that the delivery of the MSC-derived secretome may represent a therapeutic strategy to limit cardiac hypertrophy. However, additional in vivo studies are needed to prove this hypothesis.

Angiogenesis and angiocrines regulating heart growth

Endothelial cells (ECs) line the inner surface of all blood and lymphatic vessels throughout the body, making endothelium one of the largest tissues. In addition to its transport function, endothelium is now appreciated as a dynamic organ actively participating in angiogenesis, permeability and vascular tone regulation, as well as in the development and regeneration of tissues. The identification of endothelial-derived secreted factors, angiocrines, has revealed non-angiogenic mechanisms of endothelial cells in both physiological and pathological tissue remodeling. In the heart, ECs play a variety of important roles during cardiac development as well as in growth, homeostasis and regeneration of the adult heart. To date, several angiocrines affecting cardiomyocyte growth in response to physiological or pathological stimuli have been identified. In this review, we discuss the effects of angiogenesis and EC-mediated signaling in the regulation of cardiac hypertrophy. Identification of the molecular and metabolic signals from ECs during physiological and pathological cardiac growth could provide novel therapeutic targets to treat heart failure, as endothelium is emerging as one of the potential target organs in cardiovascular and metabolic diseases.

AP-2β/KCTD1 Control Distal Nephron Differentiation and Protect against Renal Fibrosis

The developmental mechanisms that orchestrate differentiation of specific nephron segments are incompletely understood, and the factors that maintain their terminal differentiation after nephrogenesis remain largely unknown. Here, the transcription factor AP-2β is shown to be required for the differentiation of distal tubule precursors into early stage distal convoluted tubules (DCTs) during nephrogenesis. In contrast, its downstream target KCTD1 is essential for terminal differentiation of early stage DCTs into mature DCTs, and impairment of their terminal differentiation owing to lack of KCTD1 leads to a severe salt-losing tubulopathy. Moreover, sustained KCTD1 activity in the adult maintains mature DCTs in this terminally differentiated state and prevents renal fibrosis by repressing β-catenin activity, whereas KCTD1 deficiency leads to severe renal fibrosis. Thus, the AP-2β/KCTD1 axis links a developmental pathway in the nephron to the induction and maintenance of terminal differentiation of DCTs that actively prevents their de-differentiation in the adult and protects against renal fibrosis.

Focus on the Role of NLRP3 Inflammasome in Diseases

Inflammation is a protective reaction activated in response to detrimental stimuli, such as dead cells, irritants or pathogens, by the evolutionarily conserved immune system and is regulated by the host. The inflammasomes are recognized as innate immune system sensors and receptors that manage the activation of caspase-1 and stimulate inflammation response. They have been associated with several inflammatory disorders. The NLRP3 inflammasome is the most well characterized. It is so called because NLRP3 belongs to the family of nucleotide-binding and oligomerization domain-like receptors (NLRs). Recent evidence has greatly improved our understanding of the mechanisms by which the NLRP3 inflammasome is activated. Additionally, increasing data in animal models, supported by human studies, strongly implicate the involvement of the inflammasome in the initiation or progression of disorders with a high impact on public health, such as metabolic pathologies (obesity, type 2 diabetes, atherosclerosis), cardiovascular diseases (ischemic and non-ischemic heart disease), inflammatory issues (liver diseases, inflammatory bowel diseases, gut microbiome, rheumatoid arthritis) and neurologic disorders (Parkinson’s disease, Alzheimer’s disease, multiple sclerosis, amyotrophic lateral sclerosis and other neurological disorders), compared to other molecular platforms. This review will provide a focus on the available knowledge about the NLRP3 inflammasome role in these pathologies and describe the balance between the activation of the harmful and beneficial inflammasome so that new therapies can be created for patients with these diseases.

Useful applications of growth factors for cardiovascular regenerative medicine

Novel advances for cardiovascular diseases (CVDs) include regenerative approaches for fibrosis, hypertrophy, and neoangiogenesis. Studies indicate that growth factor (GF) signaling could promote heart repair since most of the evidence is derived from preclinical models. Observational studies have evaluated GF serum/plasma levels as feasible biomarkers for risk stratification of CVDs. Noteworthy, two clinical interventional published studies showed that the administration of growth factors (GFs) induced beneficial effect on left ventricular ejection fraction (LVEF), myocardial perfusion, end-systolic volume index (ESVI). To date, large scale ongoing studies are in Phase I-II and mostly focussed on intramyocardial (IM), intracoronary (IC) or intravenous (IV) administration of vascular endothelial growth factor (VEGF) and fibroblast growth factor-23 (FGF-23) which result in the most investigated GFs in the last 10 years. Future data of ongoing randomized controlled studies will be crucial in understanding whether GF-based protocols could be in a concrete way effective in the clinical setting.

Angiogenic Endothelial Cell Signaling in Cardiac Hypertrophy and Heart Failure

Endothelial cells are, by number, one of the most abundant cell types in the heart and active players in cardiac physiology and pathology. Coronary angiogenesis plays a vital role in maintaining cardiac vascularization and perfusion during physiological and pathological hypertrophy. On the other hand, a reduction in cardiac capillary density with subsequent tissue hypoxia, cell death and interstitial fibrosis contributes to the development of contractile dysfunction and heart failure, as suggested by clinical as well as experimental evidence. Although the molecular causes underlying the inadequate (with respect to the increased oxygen and energy demands of the hypertrophied cardiomyocyte) cardiac vascularization developing during pathological hypertrophy are incompletely understood. Research efforts over the past years have discovered interesting mediators and potential candidates involved in this process. In this review article, we will focus on the vascular changes occurring during cardiac hypertrophy and the transition toward heart failure both in human disease and preclinical models. We will summarize recent findings in transgenic mice and experimental models of cardiac hypertrophy on factors expressed and released from cardiomyocytes, pericytes and inflammatory cells involved in the paracrine (dys)regulation of cardiac angiogenesis. Moreover, we will discuss major signaling events of critical angiogenic ligands in endothelial cells and their possible disturbance by hypoxia or oxidative stress. In this regard, we will particularly highlight findings on negative regulators of angiogenesis, including protein tyrosine phosphatase-1B and tumor suppressor p53, and how they link signaling involved in cell growth and metabolic control to cardiac angiogenesis. Besides endothelial cell death, phenotypic conversion and acquisition of myofibroblast-like characteristics may also contribute to the development of cardiac fibrosis, the structural correlate of cardiac dysfunction. Factors secreted by (dysfunctional) endothelial cells and their effects on cardiomyocytes including hypertrophy, contractility and fibrosis, close the vicious circle of reciprocal cell-cell interactions within the heart during pathological hypertrophy remodeling.

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.

NLRP3: A Novel Mediator in Cardiovascular Disease

Cardiovascular disease is a major cause of death worldwide. Inflammasome infiltration has been identified to play a central role in the pathological progression of certain cardiovascular diseases, such as vascular damage spanning atherosclerosis, aneurysm, or arteritis; ischemic heart disease; and other nonischemic heart diseases including diabetic cardiomyopathy, chronic heart failure, and hypertension- or virus-induced cardiac dysfunction. The NLRP3 inflammasome, a key participant in the innate immune response, requires both priming and activation signals for the initiation of inflammation. Piling evidence has revealed that the NLRP3 inflammasome could exert an inflammatory effect by inducing the secretion of proinflammatory cytokines (i.e., IL-1β, IL-18) or could cause pyroptosis, a novel programmed cell death process, in a caspase-1-dependent manner. The importance of the NLRP3 inflammasome in cardiac disease has been broadly investigated. In this review, we present the current knowledge regarding the function of NLRP in vascular disease, ischemic heart disease, and nonischemic heart disease and discuss the potential therapeutic options targeting the NLRP3 inflammasome.