Impaired neoangiogenesis in β₂-adrenoceptor gene-deficient mice: restoration by intravascular human β₂-adrenoceptor gene transfer and role of NFκB and CREB transcription factors

HOXD9 regulated mitophagy to promote endothelial progenitor cells angiogenesis and deep vein thrombosis recanalization and resolution

BACKGROUND

Deep vein thrombosis (DVT) is a common vascular surgical disease caused by the coagulation of blood in the deep veins, and predominantly occur in the lower limbs. Endothelial progenitor cells (EPCs) are multi-functional stem cells, which are precursors of vascular endothelial cells. EPCs have gradually evolved into a promising treatment strategy for promoting deep vein thrombus dissolution and recanalization through the stimulation of various physical and chemical factors.

METHODS

In this study, we utilized a mouse DVT model and performed several experiments including qRT-PCR, Western blot, tube formation, wound healing, Transwell assay, immunofluorescence, flow cytometry analysis, and immunoprecipitation to investigate the role of HOXD9 in the function of EPCs cells. The therapeutic effect of EPCs overexpressing HOXD9 on the DVT model and its mechanism were also explored.

RESULTS

Overexpression of HOXD9 significantly enhanced the angiogenesis and migration abilities of EPCs, while inhibiting cell apoptosis. Additionally, results indicated that HOXD9 specifically targeted the HRD1 promoter region and regulated the downstream PINK1-mediated mitophagy. Interestingly, intravenous injection of EPCs overexpressing HOXD9 into mice promoted thrombus dissolution and recanalization, significantly decreasing venous thrombosis.

CONCLUSIONS

The findings of this study reveal that HOXD9 plays a pivotal role in stimulating vascular formation in endothelial progenitor cells, indicating its potential as a therapeutic target for DVT management.

LncRNA GAS5 Attenuates Cardiac Electrical Remodeling Induced by Rapid Pacing via the miR-27a-3p/HOXa10 Pathway

Previous studies indicated long non-coding RNAs (lncRNAs) participated in the pathogenesis of atrial fibrillation (AF). However, little is known about the role of lncRNAs in AF-induced electrical remodeling. This study aimed to investigate the regulatory effect of lncRNA GAS5 (GAS5) on the electrical remodeling of neonatal rat cardiomyocytes (NRCMs) induced by rapid pacing (RP). RNA microarray analysis yielded reduced GAS5 level in NRCMs after RP. RT-qPCR, western blot, and immunofluorescence yielded downregulated levels of Nav1.5, Kv4.2, and Cav1.2 after RP, and whole-cell patch-clamp yielded decreased sodium, potassium, and calcium current. Overexpression of GAS5 attenuated electrical remodeling. Bioinformatics tool prediction analysis and dual luciferase reporter assay confirmed a direct negative regulatory effect for miR-27a-3p on lncRNA-GAS5 and HOXa10. Further analysis demonstrated that either miR-27a-3p overexpression or the knockdown of HOXa10 further downregulated Nav1.5, Kv4.2, and Cav1.2 expression. GAS5 overexpression antagonized such effects in Nav1.5 and Kv4.2 but not in Cav1.2. These results indicate that, in RP-treated NRCMs, GAS5 could restore Nav1.5 and Kv4.2 expression via the miR-27a-3p/HOXa10 pathway. However, the mechanism of GAS5 restoring Cav1.2 level remains unclear. Our study suggested that GAS5 regulated cardiac ion channels via the GAS5/miR-27a-3p/HOXa10 pathway and might be a potential therapeutic target for AF.

miR-181c targets Parkin and SMAD7 in human cardiac fibroblasts: Validation of differential microRNA expression in patients with diabetes and heart failure with preserved ejection fraction

BACKGROUND

Cardiac fibrosis represents a key feature in the pathophysiology of heart failure with preserved ejection fraction (HFpEF), a condition highly prevalent amongst geriatric patients, especially if diabetic. The microRNA miR-181c has been shown to be associated with the response to exercise training in HFpEF patients and has been also linked to diabetic cardiovascular complications. However, the underlying mechanisms have not been fully elucidated.

OBJECTIVE

To measure circulating miR-181c in elderly patients with HFpEF and DM and identify gene targets pathophysiologically relevant in HFpEF.

METHODS

We quantified circulating miR-181c in frail older adults with a confirmed diagnosis of HFpEF and diabetes, and, as control, we enrolled age-matched subjects without HFpEF and without diabetes. We validated in human cardiac fibroblasts the molecular mechanisms linking miR-181c to a pro-fibrotic response.

RESULTS

51 frail patients were included (34 patients with diabetes and HFpEF and 17 age-matched controls. We observed that miR-181c was significantly upregulated (p<0.0001) in HFpEF patients vs controls. We confirmed in vitro that miR-181c is targeting PRKN and SMAD7.

CONCLUSIONS

We demonstrate that miR-181c levels are significantly increased in frail elderly adults with diabetes and HFpEF and that miR-181c targets PRKN and SMAD7 in human cardiac fibroblasts.

Is Infantile Hemangioma a Neuroendocrine Tumor?

Infantile hemangioma (IH) is the most common infantile tumor, affecting 5–10% of newborns. Propranolol, a nonselective β-adrenergic receptor (ADRB) antagonist, is currently the first-line treatment for severe IH; however, both its mechanism of action and its main cellular target remain poorly understood. Since betablockers can antagonize the effect of natural ADRB agonists, we postulated that the catecholamine produced in situ in IH may have a role in the propranolol response. By quantifying catecholamines in the IH tissues, we found a higher amount of noradrenaline (NA) in untreated proliferative IHs than in involuted IHs or propranolol-treated IHs. We further found that the first three enzymes of the catecholamine biosynthesis pathway are expressed by IH cells and that their levels are reduced in propranolol-treated tumors. To study the role of NA in the pathophysiology of IH and its response to propranolol, we performed an in vitro angiogenesis assay in which IH-derived endothelial cells, pericytes and/or telocytes were incorporated. The results showed that the total tube formation is sensitive to propranolol only when exogenous NA is added in the three-cell model. We conclude that the IH’s sensitivity to propranolol depends on crosstalk between the endothelial cells, pericytes and telocytes in the context of a high local amount of local NA.

The Adrenergic Nerve Network in Cancer

The central and autonomic nervous systems interact and converge to build up an adrenergic nerve network capable of promoting cancer. While a local adrenergic sympathetic innervation in peripheral solid tumors influences cancer and stromal cell behavior, the brain can participate to the development of cancer through an intermixed dysregulation of the sympathoadrenal system, adrenergic neurons, and the hypothalamo-pituitary-adrenal axis. A deeper understanding of the adrenergic nerve circuitry within the brain and tumors and its interactions with the microenvironment should enable elucidation of original mechanisms of cancer and novel therapeutic strategies.

Dissection of heterocellular cross-talk in vascularized cardiac tissue mimetics

Cellular specialization and interaction with other cell types in cardiac tissue is essential for the coordinated function of cell populations in the heart. The complex interplay between cardiomyocytes, endothelial cells and fibroblasts is necessary for adaptation but can also lead to pathophysiological remodeling. To understand this complex interplay, we developed 3D vascularized cardiac tissue mimetics (CTM) to study heterocellular cross-talk in hypertrophic, hypoxic and fibrogenic environments. This 3D platform responds to physiologic and pathologic stressors and mimics the microenvironment of diseased tissue. In combination with endothelial cell fluorescence reporters, these cardiac tissue mimetics can be used to precisely visualize and quantify cellular and functional responses upon stress stimulation. Utilizing this platform, we demonstrate that stimulation of α/β-adrenergic receptors with phenylephrine (PE) promotes cardiomyocyte hypertrophy, metabolic maturation and vascularization of CTMs. Increased vascularization was promoted by conditioned medium of PE-stimulated cardiomyocytes and blocked by inhibiting VEGF or upon β-adrenergic receptor antagonist treatment, demonstrating cardiomyocyte-endothelial cross-talk. Pathophysiological stressors such as severe hypoxia reduced angiogenic sprouting and increased cell death, while TGF β2 stimulation increased collagen deposition concomitant to endothelial-to-mesenchymal transition. In sum, we have developed a cardiac 3D culture system that reflects native cardiac tissue function, metabolism and morphology - and for the first time enables the tracking and analysis of cardiac vascularization dynamics in physiology and pathology.

Is there a Chance to Promote Arteriogenesis by DPP4 Inhibitors Even in Type 2 Diabetes? A Critical Review

Cardiovascular diseases (CVD) are still the prevailing cause of death not only in industrialized countries, but even worldwide. Type 2 diabetes mellitus (type 2 DM) and hyperlipidemia, a metabolic disorder that is often associated with diabetes, are major risk factors for developing CVD. Recently, clinical trials proved the safety of gliptins in treating patients with type 2 DM. Gliptins are dipeptidyl-peptidase 4 (DPP4/CD26) inhibitors, which stabilize glucagon-like peptide-1 (GLP-1), thereby increasing the bioavailability of insulin. Moreover, blocking DPP4 results in increased levels of stromal cell derived factor 1 (SDF-1). SDF-1 has been shown in pre-clinical animal studies to improve heart function and survival after myocardial infarction, and to promote arteriogenesis, the growth of natural bypasses, compensating for the function of an occluded artery. Clinical trials, however, failed to demonstrate a superiority of gliptins compared to placebo treated type 2 DM patients in terms of cardiovascular (CV) outcomes. This review highlights the function of DPP4 inhibitors in type 2 DM, and in treating cardiovascular diseases, with special emphasis on arteriogenesis. It critically addresses the potency of currently available gliptins and gives rise to hope by pointing out the most relevant questions that need to be resolved.

The Amino-Terminal Domain of GRK5 Inhibits Cardiac Hypertrophy through the Regulation of Calcium-Calmodulin Dependent Transcription Factors

We have recently demonstrated that the amino-terminal domain of G protein coupled receptor kinase (GRK) type 5, (GRK5-NT) inhibits NFκB activity in cardiac cells leading to a significant amelioration of LVH. Since GRK5-NT is known to bind calmodulin, this study aimed to evaluate the functional role of GRK5-NT in the regulation of calcium-calmodulin-dependent transcription factors. We found that the overexpression of GRK5-NT in cardiomyoblasts significantly reduced the activation and the nuclear translocation of NFAT and its cofactor GATA-4 in response to phenylephrine (PE). These results were confirmed in vivo in spontaneously hypertensive rats (SHR), in which intramyocardial adenovirus-mediated gene transfer of GRK5-NT reduced both wall thickness and ventricular mass by modulating NFAT and GATA-4 activity. To further verify in vitro the contribution of calmodulin in linking GRK5-NT to the NFAT/GATA-4 pathway, we examined the effects of a mutant of GRK5 (GRK5-NTPB), which is not able to bind calmodulin. When compared to GRK5-NT, GRK5-NTPB did not modify PE-induced NFAT and GATA-4 activation. In conclusion, this study identifies a double effect of GRK5-NT in the inhibition of LVH that is based on the regulation of multiple transcription factors through means of different mechanisms and proposes the amino-terminal sequence of GRK5 as a useful prototype for therapeutic purposes.

Serum-derived extracellular vesicles (EVs) impact on vascular remodeling and prevent muscle damage in acute hind limb ischemia

Serum is an abundant and accessible source of circulating extracellular vesicles (EVs). Serum-EV (sEV) pro-angiogenic capability and mechanisms are herein analyzed using an in vitro assay which predicts sEV angiogenic potential in vivo. Effective sEVs (e-sEVs) also improved vascular remodeling and prevented muscle damage in a mouse model of acute hind limb ischemia. e-sEV angiogenic proteomic and transcriptomic analyses show a positive correlation with matrix-metalloproteinase activation and extracellular matrix organization, cytokine and chemokine signaling pathways, Insulin-like Growth Factor and platelet pathways, and Vascular Endothelial Growth Factor signaling. A discrete gene signature, which highlights differences in e-sEV and ineffective-EV biological activity, was identified using gene ontology (GO) functional analysis. An enrichment of genes associated with the Transforming Growth Factor beta 1 (TGFβ1) signaling cascade is associated with e-sEV administration but not with ineffective-EVs. Chromatin immunoprecipitation analysis on the inhibitor of DNA binding I (ID1) promoter region, and the knock-down of small mother against decapentaplegic (SMAD)1–5 proteins confirmed GO functional analyses. This study demonstrates sEV pro-angiogenic activity, validates a simple, sEV pro-angiogenic assay which predicts their biological activity in vivo, and identifies the TGFβ1 cascade as a relevant mediator. We propose serum as a readily available source of EVs for therapeutic purposes.

GRK2 as negative modulator of NO bioavailability: Implications for cardiovascular disease

Nitric oxide (NO), initially identified as endothelium-derived relaxing factor (EDRF), is a gaso-transmitter with important regulatory roles in the cardiovascular, nervous and immune systems. In the former, this diatomic molecule and free radical gas controls vascular tone and cardiac mechanics, among others. In the cardiovascular system, it is now understood that β-adrenergic receptor (βAR) activation is a key modulator of NO generation. Therefore, it is not surprising that the up-regulation of G protein-coupled receptor kinases (GRKs), in particular GRK2, that restrains βAR activity contributes to impaired cardiovascular functions via alteration of NO bioavailability. This review, will explore the specific interrelation between βARs, GRK2 and NO in the cardiovascular system and their inter-relationship for the pathogenesis of the onset of disease. Last, we will update the readers on the current status of GRK2 inhibitors as a potential therapeutic strategy for heart failure with an emphasis on their ability of rescuing NO bioavailability.

Adrenergic signaling in heart failure and cardiovascular aging

Both cardiovascular disease and aging are associated with changes in the sympathetic nervous system. Indeed, mounting evidence indicates that adrenergic receptors are functionally involved in numerous processes underlying both aging and cardiovascular disorders, in particular heart failure. This article will review the pathophysiological role of the sympathetic nervous system in heart failure and cardiovascular aging.

Repurposing Drugs in Oncology (ReDO)-Propranolol as an anti-cancer agent

Propranolol (PRO) is a well-known and widely used non-selective beta-adrenergic receptor antagonist (beta-blocker), with a range of actions which are of interest in an oncological context. PRO displays effects on cellular proliferation and invasion, on the immune system, on the angiogenic cascade, and on tumour cell sensitivity to existing treatments. Both pre-clinical and clinical evidence of these effects, in multiple cancer types, is assessed and summarised and relevant mechanisms of action outlined. In particular there is evidence that PRO is effective at multiple points in the metastatic cascade, particularly in the context of the post-surgical wound response. Based on this evidence the case is made for further clinical investigation of the anticancer effects of PRO, particularly in combination with other agents. A number of trials are on-going, in different treatment settings for various cancers.

Oral propranolol in early stages of retinopathy of prematurity

OBJECTIVE

To assess the effect of oral propranolol on the progression of early stages of retinopathy of prematurity (ROP) in very low birth weight (VLBW) infants.

METHODS

We analyzed VLBW infants with ROP (stages 2-3, zones II-III). Newborns received oral propranolol (0.5 mg/kg/dose q8h), and were monitored throughout the treatment period for possible side effects. Propranolol was administered until regression of ROP. A historic control group of patients with equivalent ROP was used. We compared characteristics of both groups and the progression of retinopathy.

RESULTS

Forty-seven newborns were included, 20 in the propranolol group and 27 in the control group. There were no significant differences in gestational age, birthweight or gender. The mean duration of treatment with propranolol was 58.2±17.6 days. Most patients started treatment with stage 2 disease (65.0%), and had zone III involvement (55.0%). In the treated group, 90.0% (18/20) of patients did not require intervention with laser or bevacizumab, compared to 51.8% in the control group (P<0.005). No cases of bradycardia, hypotension or hypoglycemia were observed.

CONCLUSIONS

Oral propranolol in early stages of ROP could prevent disease progression and reduce the need for invasive rescue therapy with laser or bevacizumab. No significant side effects were reported.

β Adrenergic Receptor Kinase C-Terminal Peptide Gene-Therapy Improves β2-Adrenergic Receptor-Dependent Neoangiogenesis after Hindlimb Ischemia

After hindlimb ischemia (HI), increased catecholamine levels within the ischemic muscle can cause dysregulation of β2-adrenergic receptor (β2AR) signaling, leading to reduced revascularization. Indeed, in vivo β2AR overexpression via gene therapy enhances angiogenesis in a rat model of HI. G protein-coupled receptor kinase 2 (GRK2) is a key regulator of βAR signaling, and β adrenergic receptor kinase C-terminal peptide (βARKct), a peptide inhibitor of GRK2, has been shown to prevent βAR down-regulation and to protect cardiac myocytes and stem cells from ischemic injury through restoration of β2AR protective signaling (i.e., protein kinase B/endothelial nitric oxide synthase). Herein, we tested the potential therapeutic effects of adenoviral-mediated βARKct gene transfer in an experimental model of HI and its effects on βAR signaling and on endothelial cell (EC) function in vitro. Accordingly, in this study, we surgically induced HI in rats by femoral artery resection (FAR). Fifteen days of ischemia resulted in significant βAR down-regulation that was paralleled by an approximately 2-fold increase in GRK2 levels in the ischemic muscle. Importantly, in vivo gene transfer of the βARKct in the hindlimb of rats at the time of FAR resulted in a marked improvement of hindlimb perfusion, with increased capillary and βAR density in the ischemic muscle, compared with control groups. The effect of βARKct expression was also assessed in vitro in cultured ECs. Interestingly, ECs expressing the βARKct fenoterol, a β2AR-agonist, induced enhanced β2AR proangiogenic signaling and increased EC function. Our results suggest that βARKct gene therapy and subsequent GRK2 inhibition promotes angiogenesis in a model of HI by preventing ischemia-induced β2AR down-regulation.

Beta Adrenergic Signaling: A Targetable Regulator of Angiosarcoma and Hemangiosarcoma

Human angiosarcomas and canine hemangiosarcomas are highly aggressive cancers thought to arise from cells of vascular origin. The pathological features, morphological organization, and clinical behavior of canine hemangiosarcomas are virtually indistinct from those of human angiosarcomas. Overall survival with current standard-of-care approaches remains dismal for both humans and dogs, and each is likely to succumb to their disease within a short duration. While angiosarcomas in humans are extremely rare, limiting their study and treatment options, canine hemangiosarcomas occur frequently. Therefore, studies of these sarcomas in dogs can be used to advance treatment approaches for both patient groups. Emerging data suggest that angiosarcomas and hemangiosarcomas utilize beta adrenergic signaling to drive their progression by regulating the tumor cell niche and fine-tuning cellular responses within the tumor microenvironment. These discoveries indicate that inhibition of beta adrenergic signaling could serve as an Achilles heel for these tumors and emphasize the need to design therapeutic strategies that target tumor cell and stromal cell constituents. In this review, we summarize recent discoveries and present new hypotheses regarding the roles of beta adrenergic signaling in angiosarcomas and hemangiosarcomas. Because the use of beta adrenergic receptor antagonists is well established in human and veterinary medicine, beta blockade could provide an immediate adjunct therapy for treatment along with a tangible opportunity to improve upon the outcomes of both humans and dogs with these diseases.

β-Blockers promote angiogenesis in the mouse aortic ring assay

Recent results indicate that the reduction of β-adrenergic signaling impairs angiogenesis under ischemic conditions. Because angiogenesis may occur in the absence of ischemia, it remains to be determined whether and how β-adrenergic signaling regulates angiogenesis, which develops under normoxic conditions. The effect of β-adrenergic ligands on angiogenesis was investigated using 3-dimensional cultures of mouse aortic rings embedded in collagen type I, in which luminized microvessels develop in response to vascular endothelial growth factor (VEGF). Under normoxic conditions, both isoproterenol, a β-adrenergic receptor (β-AR) agonist, and forskolin, an adenylate cyclase activator, were unable to influence aortic microvessel sprouting. On the contrary, treatment with propranolol, a β-AR antagonist, caused an approximately 70% increase in VEGF-mediated microvessel sprouting. This effect was abolished in rings from both double β-AR and β1-AR knockout mice, but not in rings from β2-AR knockout mice. Significant increases in microvessel sprouting were also observed when mouse aortic rings from C57BL/6 mice were treated with the β1-AR-selective antagonists metoprolol and bisoprolol or with the β2-AR-selective antagonist ICI 118,551. Conversely, carvedilol, a nonselective β-AR antagonist, was unable to affect aortic sprouting. These findings suggest that some β-blockers display proangiogenic activity through a mechanism that is independent of their ability to antagonize catecholamine action. The present results also identify a new function for β-AR signaling as a facilitator for VEGF-mediated angiogenesis and have implications for understanding the mechanisms that regulate angiogenic responses under normoxic conditions.

Pathological hypertrophy reverses β2-adrenergic receptor-induced angiogenesis in mouse heart

β-adrenergic activation and angiogenesis are pivotal for myocardial function but the link between both events remains unclear. The aim of this study was to explore the cardiac angiogenesis profile in a mouse model with cardiomyocyte-restricted overexpression of β₂-adrenoceptors (β₂-TG), and the effect of cardiac pressure overload. β₂-TG mice had heightened cardiac angiogenesis, which was essential for maintenance of the hypercontractile phenotype seen in this model. Relative to controls, cardiomyocytes of β₂-TGs showed upregulated expression of vascular endothelial growth factor (VEGF), heightened phosphorylation of cAMP-responsive-element-binding protein (CREB), and increased recruitment of phospho-CREB, CREB-binding protein (CBP), and p300 to the VEGF promoter. However, when hearts were subjected to pressure overload by transverse aortic constriction (TAC), angiogenic signaling in β₂-TGs was inhibited within 1 week after TAC. β₂-TG hearts, but not controls, exposed to pressure overload for 1–2 weeks showed significant increases from baseline in phosphorylation of Ca²⁺/calmodulin-dependent kinase II (CaMKIIδ) and protein expression of p53, reduction in CREB phosphorylation, and reduced abundance of phospho-CREB, p300 and CBP recruited to the CREB-responsive element (CRE) site of VEGF promoter. These changes were associated with reduction in both VEGF expression and capillary density. While non-TG mice with TAC developed compensatory hypertrophy, (₂-TGs exhibited exaggerated hypertrophic growth at week-1 post-TAC, followed by LV dilatation and reduced fractional shortening measured by serial echocardiography. In conclusion, angiogenesis was enhanced by the cardiomyocyte (₂AR/CREB/VEGF signaling pathway. Pressure overload rapidly inhibited this signaling, likely as a consequence of activated CaMKII and p53, leading to impaired angiogenesis and functional decompensation.

β2-Adrenergic receptors in immunity and inflammation: stressing NF-κB

β2-Adrenergic receptors (β2-ARs) transduce the effects of (nor)epinephrine on a variety of cell types and act as key mediators of the body's reaction to stress. β2-ARs are also expressed on immune cells and there is ample evidence for their role in immunomodulation. A key regulator of the immune response and a target for regulation by stress-induced signals is the transcription factor Nuclear Factor-kappaB (NF-κB). NF-κB shapes the course of both innate and adaptive immune responses and plays an important role in susceptibility to disease. In this review, we summarise the literature that has been accumulated in the past 20years on adrenergic modulation of NF-κB function. We here focus on the molecular basis of the reported interactions and show that both physiological and pharmacological triggers of β2-ARs intersect with the NF-κB signalling cascade at different levels. Importantly, the action of β2-AR-derived signals on NF-κB activity appears to be highly cell type specific and gene selective, providing opportunities for the development of selective NF-κB modulators.

Effects of isoprenaline on endothelial connexins and angiogenesis in a human endothelial cell culture system

Downregulation of endothelial connexins has been shown to result in impaired angiogenesis. Isoprenaline is known to upregulate Cx43 in cardiomyocytes. Effects of isoprenaline on endothelial connexins are unknown. We wanted to investigate whether isoprenaline might induce upregulation of connexins Cx37, Cx40, or Cx43 in human endothelial cells and whether it may promote angiogenesis. Human umbilical vein endothelial cells (HUVECs) were cultured until confluence (5 days) and subsequently seeded in Matrigel in vitro angiogenesis assays for 18 h. During the entire cell culture and angiogenesis period, cells were treated with vehicle or isoprenaline (100 nM). Finally, the resulting angiogenetic network was investigated (immuno)histologically. Moreover, expression of Cx37, Cx40, and Cx43 was determined by Western blot. In addition, we measured functional intercellular gap junction coupling by dye injection using patch clamp technique. Isoprenaline resulted in significantly enhanced expression of endothelial Cx43 and to a lower degree of Cx40 and Cx37. The number of coupling cells was significantly increased. Regarding angiogenesis, we observed significantly enhanced formation of branches and a higher complexity of the tube networks with more branches/length. Isoprenaline increases endothelial connexin expression and intercellular coupling and promotes tube formation.

The use of propranolol in the treatment of infantile haemangiomas: an update on potential mechanisms of action

Currently, propranolol is the preferred treatment for problematic proliferating infantile haemangiomas (IHs). The rapid action of propranolol has been shown to be especially dramatic in IHs involving dyspnoea, haemodynamic compromise, palpebral occlusion or ulceration. Another remarkable aspect of propranolol treatment revealed that the growth of the IHs was not only stabilized, but also that the improvement continued until complete involution was achieved, leading to a considerable shortening of the natural course of IH. However, the mechanisms underlying the effects of propranolol have not been fully elucidated. Recent studies have offered evidence of a variety of mechanisms. These include the promotion of pericyte-mediated vasoconstriction, the inhibition of vasculogenesis and catecholamine-induced angiogenesis, the disruption of haemodynamic force-induced cell survival, and the inactivation of the renin-angiotensin system. This review summarizes these mechanisms and the new concepts that are emerging in this area of research. Moreover, several molecular mechanisms by which propranolol may modify neovascularization in IH have also been proposed. The antihaemangioma effect of propranolol may not be attributable to a single mechanism, but rather to a combination of events that have not yet been elucidated or understood. Further studies are needed to evaluate and verify these mechanisms to gain a greater understanding of the effects of the intake of propranolol on haemangioma involution.

New small molecules, ISA27 and SM13, inhibit tumour growth inducing mitochondrial effects of p53

BACKGROUND

p53 is a transcription factor with tumour suppressor properties, which is able to induce mitochondrial apoptosis independently of its transcriptional activity. We recently synthesised two new compounds (ISA27 and SM13), which block p53-MDM2 interaction and induce apoptosis in p53 wild-type (WT) tumour cells. The aim of this study was to verify the effectiveness of these compounds in tumours carrying a mutated form of p53 gene with no transcriptional activity.

METHODS

In vitro we evaluated the effectiveness of our compounds in cancer cell lines carrying WT, mutated and null p53 gene. In vivo study was performed in Balb/c nude mice and the mitochondrial-dependent apoptotic signalling was evaluated by western blot.

RESULTS

Both ISA27 and SM13 reduced cell proliferation and induced apoptosis in vitro in cells carrying either p53 WT or mutated gene, suggesting that its effect is independent from p53 transcriptional activity. On the contrary, SM13 had no effect in a p53 null cell line. In vivo, ISA27 and SM13 induced cancer cell death in a dose-dependent manner through the activation of the mitochondrial-dependent death signalling in p53-mutated cells. In vivo, SM13 reduced tumour growth.

CONCLUSIONS

Our study proposes SM13 as anticancer compound to use for the treatment of p53-dependent tumours, even in the absence of p53 transcriptional activity.

Arterial Innervation in Development and Disease

Innervation of arteries by sympathetic nerves is well known to control blood supply to organs. Recent studies have elucidated the mechanisms that regulate the development of arterial innervation and show that in addition to vascular tone, sympathetic nerves may also influence arterial maturation and growth. Understanding sympathetic arterial innervation may lead to new approaches to treat peripheral arterial disease and hypertension.

CaMKII protects MKP-1 from proteasome degradation in endothelial cells

CaMKs are a widely distributed family of kinases with multiple and often cell specific effects on intracellular signal transduction pathway. In endothelial cells, it has been recognized a role for CamKII in several pathways such as eNOS activation and nitric oxide production. It is not clear though, whether CaMKII interfere with other endothelial cell functions such as ERK activation and cell proliferation. We explored this issue in primary cultured rat endothelial cells and we evaluated the effect on endothelial cell proliferation and DNA synthesis. CaMKII inhibition through Cantide, conducted into the cell through Antoennapedia (ANT-CN), showed positive effects on proliferation and H(3)-thimdine incorporation similar to insulin stimulation. Accordingly, both CaMKII pharmacological inhibition and silencing through shRNA produced activation of the p44/42 MAPK. These observations leaded to the hypothesis that CamKII could regulate p44/p42 by interfering with specific ERK phosphatases. Indeed, we found that CaMKII interacts and protect the dual specific phosphatase MKP-1 from proteasome mediated degradation while this complex is disrupted by CaMKII inhibitors. This study reveals that CaMKII, besides phosphorylation through the known ras-raf-mek pathway, can regulate also dephosphorylation of p44/p42 by modulation of MKP-1 level. This novel finding opens to a novel scenario in regulation of endothelial cell functions.

β-Adrenoceptors differentially regulate vascular tone and angiogenesis of rat aorta via ERK1/2 and p38

β-Adrenoceptors (β-ARs) modulate ERK1/2 and p38 in different cells, but little is known about the contribution of these signaling pathways to the function of β-ARs in vascular tissue. Immunoblotting analysis of rat aortic rings, primary endothelial (ECs) and smooth muscle cells (SMCs) isolated from aorta showed that β-AR stimulation with isoprenaline activated p38 in aortic rings and in both cultured cell types, whereas it had a dual effect on ERK1/2 phosphorylation, decreasing it in ECs while increasing it in SMCs. These effects were reversed by propranolol, which by itself increased p-ERK1/2 in ECs. Isoprenaline β-AR mediated vasodilation of aortic rings was potentiated by the ERK1/2 inhibitor, U0126, in the presence or absence of endothelium or L-NAME, whereas inhibition of p38 had no impact. Isoprenaline moderately decreased sprouting from aorta rings in the Matrigel angiogenesis assay; conversely propranolol not only prevented isoprenaline inhibition, but stimulated angiogenesis. ERK1/2 inhibition decreased angiogenesis, while a dramatic stimulation was observed by p38 blockade. Our results suggest that ERK1/2 activation after β-ARs stimulation in the smooth muscle hinders the vasodilator effect of isoprenaline, but in the endothelium β-ARs decreases ERK1/2 and increases p38 activity reducing therefore angiogenesis.

Antitumor activity of (R,R')-4-methoxy-1-naphthylfenoterol in a rat C6 glioma xenograft model in the mouse

(R,R’)-4-methoxy-1-naphthylfenoterol (MNF) inhibits cancer cell proliferation in vitro through cell-type specific modulation of β2-adrenergic receptor and/or cannabinoid receptor function. Here, we report an investigation into antitumor activity of MNF in rat C6 glioma cells. The potent antiproliferative action of MNF in these cells (IC₅₀ of ∼1 nmol/L) was refractory to pharmacological inhibition of β2-adrenergic receptor while a synthetic inverse agonist of cannabinoid receptor 1 significantly blocked MNF activity. The antitumor activity of MNF was then assessed in a C6 glioblastoma xenograft model in mice. Three days after subcutaneous implantation of C6 cells into the lower flank of nude mice, these animals were subjected to i.p. injections of saline or MNF (2 mg/kg) for 19 days and tumor volumes were measured over the course of the experiment. Gene expression analysis, quantitative RT-PCR and immunoblot assays were performed on the tumors after treatment. Significant reduction in mean tumor volumes was observed in mice receiving MNF when compared with the saline-treated group. We identified clusters in expression of genes involved in cellular proliferation, as well as molecular markers for glioblastoma that were significantly downregulated in tumors of MNF-treated mice as compared to saline-injected controls. The efficacy of MNF against C6 glioma cell proliferation in vivo and in vitro was accompanied by marked reduction in the expression of cell cycle regulator proteins. This study is the first demonstration of MNF-dependent chemoprevention of a glioblastoma xenograft model and may offer a potential mechanism for its anticancer action in vivo.

Mitochondrial G protein coupled receptor kinase 2 regulates proinflammatory responses in macrophages

G-protein-coupled receptor kinase 2 (GRK2) levels are elevated in inflammation but its role is not clear yet. Here we show that GRK2 expression is dependent on NFκB transcriptional activity. In macrophages, LPS induces GRK2 accumulation in mitochondria increasing biogenesis. The overexpression of the carboxy-terminal domain of GRK2 (βARK-ct), known to displace GRK2 from plasma membranes, induces earlier localization of GRK2 to mitochondria in response to LPS leading to increased mt-DNA transcription and reduced ROS production and cytokine expression. Our study shows the relevance of GRK2 subcellular localization in macrophage biology and its potential therapeutic properties in inflammation.

Norepinephrine potentiates proinflammatory responses of human vaginal epithelial cells

The vaginal epithelium provides a barrier to pathogens and recruits immune defenses through the secretion of cytokines and chemokines. Several studies have shown that mucosal sites are innervated by norepinephrine-containing nerve fibers. Here we report that norepinephrine potentiates the proinflammatory response of human vaginal epithelial cells to products produced by Staphylococcus aureus, a pathogen that causes menstrual toxic shock syndrome. The cells exhibit immunoreactivity for catecholamine synthesis enzymes and the norepinephrine transporter. Moreover, the cells secrete norepinephrine and dopamine at low concentrations. These results indicate that norepinephrine may serve as an autocrine modulator of proinflammatory responses in the vaginal epithelium.

The role of β-adrenergic receptor signaling in the proliferation of hemangioma-derived endothelial cells

BACKGROUND

Infantile hemangioma (IH) is a benign vascular neoplasm that arises from the abnormal proliferation of endothelial cells and enhanced angiogenesis. Recently, propranolol has been found to be effective in the management of IH, suggesting that β-adrenergic receptors (β-ARs) may play an important role in the pathogenesis of IH.

RESULTS

In the present study, we investigated the β-adrenergic signaling that is associated with hemangioma-derived endothelial cell (HemEC) proliferation. The results showed that both β1- and β2-ARs were expressed in HemECs. Stimulation of the β-ARs by isoprenaline induced cell proliferation and elevation of second messenger cAMP levels. The proliferation-promoting action of isoprenaline was abolished by a β1-selective antagonist and was more effectively abolished by a β2-selective antagonist; the mechanism for the action of the antagonists was a G0/G1 phase cell cycle arrest which was associated with decreased cyclin D1, CDK-4, CDK-6 and phospho-Rb expression. Pre-treatment of the cells with VEGFR-2 or ERK inhibitors also prevented the isoprenaline-mediated proliferation of cells. In agreement with the involvement of β-ARs and VEGFR-2 in the HemEC response, β-AR antagonists and the VEGFR-2 inhibitor significantly attenuated isoprenaline-induced ERK phosphorylation. Moreover, treating the cells with isoprenaline markedly increased VEGF-A expression and VEGFR-2 activity in a β2-AR-dependent manner.

CONCLUSIONS

We have demonstrated that the activation of the β-ARs in the ERK pathway may be important mechanisms in promoting HemEC growth. Furthermore, stimulation of the β-AR may transactivate VEGFR-2 signaling and further increase HemEC proliferation.

β-blockers: a novel class of antitumor agents

β-adrenergic signaling modulates key signaling pathways that are important for tumor-promoting processes, and numerous mechanisms of action have been elucidated. Preclinical studies have demonstrated that β-adrenergic antagonists, or β-blockers, can block multiple fundamental biologic processes underlying the progression and metastasis of tumors, including the inhibition of cell proliferation, migration, invasion, resistance to programmed cell death, and tumor angiogenesis and metastasis. Human pharmacoepidemiologic studies suggest that β-blockers have a role in inhibiting cancer progression and metastasis in combination with standard therapies. Furthermore, a number of prospective studies have demonstrated that β-blockers are effective at halting infantile hemangioma growth. These findings shed light on the novel perspective of using β-blockers as a class of potential antitumor agents in clinical oncology.

Myocardial β(2) -adrenoceptor gene delivery promotes coordinated cardiac adaptive remodelling and angiogenesis in heart failure

BACKGROUND AND PURPOSE

We investigated whether β(2) -adrenoceptor overexpression could promote angiogenesis and improve blood perfusion and left ventricular (LV) remodeling of the failing heart.

EXPERIMENTAL APPROACH

We explored the angiogenic effects of β(2) -adrenoceptor overexpression in a rat model of post-myocardial infarction (MI) heart failure (HF). Cardiac adenoviral-mediated β(2) -adrenoceptor overexpression was obtained via direct intramyocardial injection 4-weeks post-MI. Adenovirus(Ad)-GFP and saline injected rats served as controls. Furthermore, we extended our observation to β(2) -adrenoceptor -/- mice undergoing MI.

KEY RESULTS

Transgenes were robustly expressed in the LV at 2 weeks post-gene therapy, whereas their expression was minimal at 4-weeks post-gene delivery. In HF rats, cardiac β(2) -adrenoceptor overexpression resulted in enhanced basal and isoprenaline-stimulated cardiac contractility at 2-weeks post-gene delivery. At 4 weeks post-gene transfer, Ad-β(2) -adrenoceptor HF rats showed improved LV remodeling and cardiac function. Importantly, β(2) -adrenoceptor overexpression was associated with a markedly increased capillary and arteriolar length density and enhanced in vivo myocardial blood flow and coronary reserve. At the molecular level, cardiac β(2) -adrenoceptor gene transfer induced the activation of the VEGF/PKB/eNOS pro-angiogenic pathway. In β(2) -adrenoceptor-/- mice, we found a ~25% reduction in cardiac capillary density compared with β(2) -adrenoceptor+/+ mice. The lack of β(2) -adrenoceptors was associated with a higher mortality rate at 30 days and LV dilatation, and a worse global cardiac contractility compared with controls.

CONCLUSIONS AND IMPLICATION

β(2) -Adrenoceptors play an important role in the regulation of the angiogenic response in HF. The activation of VEGF/PKB/eNOS pathway seems to be strongly involved in this mechanism.

Endothelial cells are able to synthesize and release catecholamines both in vitro and in vivo

Recently it has been demonstrated that catecholamines are produced and used by macrophages and mediate immune response. The aim of this study is to verify whether endothelial cells (ECs), which are of myeloid origin, can produce catecholamines. We demonstrated that genes coding for tyrosine hydroxylase, Dopa decarboxylase, dopamine β hydroxylase (DβH), and phenylethanolamine-N-methyl transferase, enzymes involved in the synthesis of catecholamines, are all expressed in basal conditions in bovine aorta ECs, and their expression is enhanced in response to hypoxia. Moreover, hypoxia enhances catecholamine release. To evaluate the signal transduction pathway that regulates catecholamine synthesis in ECs, we overexpressed in bovine aorta ECs either protein kinase A (PKA) or the transcription factor cAMP response element binding, because PKA/cAMP response element binding activation induces tyrosine hydroxylase transcription and activity in response to stress. Both cAMP response element binding and PKA overexpression enhance DβH and phenylethanolamine-N-methyl transferase gene expression and catecholamine release, whereas H89, inhibitor of PKA, exerts the opposite effect, evidencing the role of PKA/cAMP response element binding transduction pathway in the regulation of catecholamine release in bovine aorta ECs. We then evaluated by immunohistochemistry the expression of tyrosine hydroxylase, Dopa decarboxylase, DβH, and phenylethanolamine-N-methyl transferase in femoral arteries from hindlimbs of C57Bl/6 mice 3 days after removal of the common femoral artery to induce chronic ischemia. Ischemia evokes tyrosine hydroxylase, Dopa decarboxylase, DβH, and phenylethanolamine-N-methyl transferase expression in the endothelium. Finally, the pharmacological inhibition of catecholamine release by fusaric acid, an inhibitor of DβH, reduces the ability of ECs to form network-like structures on Matrigel matrix. In conclusion, our study demonstrates for the first time that ECs are able to synthesize and release catecholamines in response to ischemia.

Angiogenesis in chronic obstructive pulmonary disease: a translational appraisal

Angiogenesis is a crucial component of lung pathophysiology, not only in cancer but also in other disorders, such as chronic obstructive pulmonary disease (COPD). In COPD angiogenesis is definitely able to control and orchestrate the progression of airway remodeling. Herein, we provide several remarkable translational aspects of angiogenesis in COPD, exploring both basic and clinical research in this field. Indeed, we present a number of pro- and anti-angiogenic factors, which can be also used as potential biomarkers to monitor disease progression.

β2AR antagonists and β2AR gene deletion both promote skin wound repair processes

Skin wound healing is a complex process requiring the coordinated, temporal orchestration of numerous cell types and biological processes to regenerate damaged tissue. Previous work has demonstrated that a functional β-adrenergic receptor autocrine/paracrine network exists in skin, but the role of β2-adrenergic receptor (β2AR) in wound healing is unknown. A range of in vitro (single-cell migration, immunoblotting, ELISA, enzyme immunoassay), ex vivo (rat aortic ring assay), and in vivo (chick chorioallantoic membrane assay, zebrafish, murine wild-type, and β2AR knockout excisional skin wound models) models were used to demonstrate that blockade or loss of β2AR gene deletion promoted wound repair, a finding that is, to our knowledge, previously unreported. Compared with vehicle-only controls, β2AR antagonism increased angiogenesis, dermal fibroblast function, and re-epithelialization, but had no effect on wound inflammation in vivo. Skin wounds in β2AR knockout mice contracted and re-epithelialized faster in the first few days of wound repair in vivo. β2AR antagonism enhanced cell motility through distinct intracellular signalling mechanisms and increased vascular endothelial growth factor secretion from keratinocytes. β2AR antagonism promoted wound repair processes in the early stages of wound repair, revealing a possible new avenue for therapeutic intervention.

Age-related impairment in insulin release: the essential role of β(2)-adrenergic receptor

In this study, we investigated the significance of β(2)-adrenergic receptor (β(2)AR) in age-related impaired insulin secretion and glucose homeostasis. We characterized the metabolic phenotype of β(2)AR-null C57Bl/6N mice (β(2)AR(-/-)) by performing in vivo and ex vivo experiments. In vitro assays in cultured INS-1E β-cells were carried out in order to clarify the mechanism by which β(2)AR deficiency affects glucose metabolism. Adult β(2)AR(-/-) mice featured glucose intolerance, and pancreatic islets isolated from these animals displayed impaired glucose-induced insulin release, accompanied by reduced expression of peroxisome proliferator-activated receptor (PPAR)γ, pancreatic duodenal homeobox-1 (PDX-1), and GLUT2. Adenovirus-mediated gene transfer of human β(2)AR rescued these defects. Consistent effects were evoked in vitro both upon β(2)AR knockdown and pharmacologic treatment. Interestingly, with aging, wild-type (β(2)AR(+/+)) littermates developed impaired insulin secretion and glucose tolerance. Moreover, islets from 20-month-old β(2)AR(+/+) mice exhibited reduced density of β(2)AR compared with those from younger animals, paralleled by decreased levels of PPARγ, PDX-1, and GLUT2. Overexpression of β(2)AR in aged mice rescued glucose intolerance and insulin release both in vivo and ex vivo, restoring PPARγ/PDX-1/GLUT2 levels. Our data indicate that reduced β(2)AR expression contributes to the age-related decline of glucose tolerance in mice.

Sympathetic nervous system regulates bone marrow-derived cell egress through endothelial nitric oxide synthase activation: role in postischemic tissue remodeling

OBJECTIVE

Catecholamines have been shown to control bone marrow (BM)-derived cell egress, yet the cellular and molecular mechanisms involved in this effect and their subsequent participation to postischemic vessel growth are poorly understood.

METHODS AND RESULTS

Tyrosine hydroxylase mRNA levels, as well as dopamine (DA) and norepinephrine (NE) contents, were increased in the ischemic BM of mice with right femoral artery ligation. Angiographic score, capillary density, and arteriole number were markedly increased by treatments with DA (IP, 50 mg/kg, 5 days) or NE (IP, 2.5 mg/kg, 5 days). Using chimeric mice lethally irradiated and transplanted with BM-derived cells from green fluorescent protein mice, we showed that DA and NE enhanced by 70% (P<0.01) and 62% (P<0.001), respectively, the number of green fluorescent protein-positive BM-derived cells in ischemic tissue and promoted their ability to differentiate into cells with endothelial and inflammatory phenotypes. Similarly, both DA and NE increased the in vitro differentiation of cultured BM-derived cells into cells with endothelial phenotype. This increase was blunted by the nitric oxide synthase inhibitor Nω-nitro-L-arginine methyl ester. DA and NE also upregulated the number of CD45-positive cells in blood 3 days after ischemia and that of macrophages in ischemic tissue 21 days after ischemia. Of interest, DA and NE increased BM endothelial nitric oxide synthase (eNOS) mRNA levels and were unable to promote BM-derived cell mobilization in chimeric eNOS-deficient mice lethally irradiated and transplanted with BM-derived cells from wild-type animals. Furthermore, administration of a β2 adrenergic agonist (clenbuterol, IP, 2 mg/kg, 5 days) and that of a dopaminergic D1/D5 receptor agonist (SKF-38393, IP, 2.5 mg/kg, 5 days) also enhanced BM-derived cell mobilization and subsequently postischemic vessel growth. CONCLUSION These results unravel, for the first time, a major role for the sympathetic nervous system in BM-derived cell egress through stromal eNOS activation.

Norepinephrine promotes the β1-integrin-mediated adhesion of MDA-MB-231 cells to vascular endothelium by the induction of a GROα release

The migratory activity of tumor cells and their ability to extravasate from the blood stream through the vascular endothelium are important steps within the metastasis cascade. We have shown previously that norepinephrine is a potent inducer of the migration of MDA-MB-468 human breast carcinoma cells and therefore investigated herein, whether the interaction of these cells as well as MDA-MB-231 and MDA-MB-435S human breast carcinoma cells with the vascular endothelium is affected by this neurotransmitter as well. By means of a flow-through assay under physiologic flow conditions, we show that norepinephrine induces an increase of the adhesion of the MDA-MB-231 cells, but not of MDA-MB-468 and MDA-MB-435S cells to human pulmonary microvascular endothelial cells (HMVEC). The adhesion of MDA-MB-231 cells was based on a norepinephrine-mediated release of GROα from HMVECs. GROα caused a β1-integrin-mediated increase of the adhesion of MDA-MB-231 cells. Most interestingly, this effect of norepinephrine, similar to the aforementioned induction of migration in MDA-MB-468 cells, was mediated by β-adrenergic receptors and therefore abrogated by β-blockers. In conclusion, norepinephrine has cell line-specific effects with regard to certain steps of the metastasis cascade, which are conjointly inhibited by clinically established β-blockers. Therefore, these results may deliver a molecular explanation for our recently published retrospective data analysis of patients with breast cancer which shows that β-blockers significantly reduce the development of metastases.

Adrenergic mechanism in the control of endothelial function

There is considerable evidence that many disease are associated with endothelial dysfunction and reduced nitric oxide production such as hypertension, obesity, dyslipidemias, diabetes, heart failure, atherosclerosis. Notably these conditions are also characterized by alteration in the adrenergic tone. Whether these two mechanisms are just epiphenomenal each other or there is a functional link, it is still to be established. A starting ground to establish this issue is that vascular endothelium plays an important role in the function of cardiovascular system and that adrenergic receptors on endothelial cells contribute to the regulation of vasomotor tone. The aim of this excerpt is to review current knowledge on the physiology of endothelial adrenergic receptors to contribute to the basis for newer and better approaches to endothelial dysfunction in the setup of cardiovascular conditions.