Vascular endothelial growth factor-D mediates fibrogenic response in myofibroblasts

Causal effect of vascular endothelial growth factor on the risk of atrial fibrillation: a two-sample Mendelian randomization study

Background

Observational studies have found that vascular endothelial growth factor (VEGF) levels are associated with the risk of cardiovascular disease. However, it remains unclear whether VEGF levels have a causal effect on the risk of atrial fibrillation.

Methods

A two-sample Mendelian randomization (MR) study was conducted to explore the causal relationship between VEGF levels and the risk of atrial fibrillation. Genetic variants associated with VEGF [VEGF-A, VEGF-C, VEGF-D, VEGF receptor-2 (VEGFR-2), VEGFR-3] and atrial fibrillation (atrial fibrillation, atrial fibrillation and flutter) were used as instrumental variables. Data on genetic variants were obtained from published genome-wide association studies (GWAS) or the IEU Open GWAS project. Inverse-variance weighted (IVW) analysis was used as the primary basis for the results, and sensitivity analyses were used to reduce bias. Causal relationships were expressed as odds ratio (OR) with 95% confidence interval (CI), and a P-value of <0.1 corrected for False Discovery Rate (FDR) (PFDR  < 0.1) was considered to have a significant causal relationship.

Results

Genetically predicted high levels of VEGF-A [OR = 1.025 (95%CI: 1.004-1.047), PFDR  = 0.060] and VEGF-D [OR = 1.080 (95%CI: 1.039-1.123), PFDR  = 0.001]] were associated with an increased risk of atrial fibrillation, while no causal relationship was observed between VEGF-C (PFDR  = 0.419), VEGFR-2 (PFDR  = 0.784), and VEGFR-3 (PFDR  = 0.899) and atrial fibrillation risk. Moreover, only genetically predicted high levels of VEGF-D [OR = 1.071 (95%CI: 1.014-1.132), PFDR  = 0.087] increased the risk of atrial fibrillation and flutter. Sensitivity analysis demonstrated that the relationship between VEGF-D levels and the risk of atrial fibrillation was robust.

Conclusion

This study supports a causal association between high VEGF-D levels and increased risk of atrial fibrillation.

Human Keratinocytes and Fibroblasts Co-Cultured on Silk Fibroin Scaffolds Exosomally Overrelease Angiogenic and Growth Factors

Objectives: The optimal healing of skin wounds, deep burns, and chronic ulcers is an important clinical problem. Attempts to solve it have been driving the search for skin equivalents based on synthetic or natural polymers. Methods: Consistent with this endeavor, we used regenerated silk fibroin (SF) from Bombyx mori to produce a novel compound scaffold by welding a 3D carded/hydroentangled SF-microfiber-based nonwoven layer (C/H-3D-SFnw; to support dermis engineering) to an electrospun 2D SF nanofiber layer (ESFN; a basal lamina surrogate). Next, we assessed-via scanning electron microscopy, attenuated total reflectance Fourier transform infrared spectroscopy, differential scanning calorimetry, mono- and co-cultures of HaCaT keratinocytes and adult human dermal fibroblasts (HDFs), dsDNA assays, exosome isolation, double-antibody arrays, and angiogenesis assays-whether the C/H-3D-SFnws/ESFNs would allow the reconstitution of a functional human skin analog in vitro. Results: Physical analyses proved that the C/H-3D-SFnws/ESFNs met the requirements for human soft-tissue-like implants. dsDNA assays revealed that co-cultures of HaCaTs (on the 2D ESFN surface) and HDFs (inside the 3D C/H-3D-SFnws) grew more intensely than did the respective monocultures. Double-antibody arrays showed that the CD9⁺/CD81⁺ exosomes isolated from the 14-day pooled growth media of HDF and/or HaCaT mono- or co-cultures conveyed 35 distinct angiogenic/growth factors (AGFs). However, versus monocultures' exosomes, HaCaT/HDF co-cultures' exosomes (i) transported larger amounts of 15 AGFs, i.e., PIGF, ANGPT-1, bFGF, Tie-2, Angiogenin, VEGF-A, VEGF-D, TIMP-1/-2, GRO-α/-β/-γ, IL-1β, IL-6, IL-8, MMP-9, and MCP-1, and (ii) significantly more strongly stimulated human dermal microvascular endothelial cells to migrate and assemble tubes/nodes in vitro. Conclusions: Our results showed that both cell-cell and cell-SF interactions boosted the exosomal release of AGFs from HaCaTs/HDFs co-cultured on C/H-3D-SFnws/ESFNs. Hence, such exosomes are an asset for prospective clinical applications as they advance cell growth and neoangiogenesis and consequently graft take and skin healing. Moreover, this new integument analog could be instrumental in preclinical and translational studies on human skin pathophysiology and regeneration.

Vascular endothelial growth factor-D plasma levels and VEGFD genetic variants are independently associated with outcomes in patients with cardiovascular disease

AIMS

The vascular endothelial growth factor (VEGF) family is involved in pathophysiological mechanisms underlying cardiovascular (CV) diseases. The aim of this study was to investigate the associations between circulating VEGF ligands and/or soluble receptors and CV outcome in patients with acute coronary syndrome (ACS) and chronic coronary syndrome (CCS).

METHODS AND RESULTS

Levels of VEGF biomarkers, including bFGF, Flt-1, KDR (VEGFR2), PlGF, Tie-2, VEGF-A, VEGF-C, and VEGF-D, were measured in the PLATO ACS cohort (n = 2091, discovery cohort). Subsequently, VEGF-D was also measured in the STABILITY CCS cohort (n = 4015, confirmation cohort) to verify associations with CV outcomes. Associations between plasma VEGF-D and outcomes were analysed by multiple Cox regression models with hazard ratios (HR [95% CI]) comparing the upper vs. the lower quartile of VEGF-D. Genome-wide association study (GWAS) of VEGF-D in PLATO identified SNPs that were used as genetic instruments in Mendelian randomization (MR) meta-analyses vs. clinical endpoints. GWAS and MR were performed in patients with ACS from PLATO (n = 10 013) and FRISC-II (n = 2952), and with CCS from the STABILITY trial (n = 10 786). VEGF-D, KDR, Flt-1, and PlGF showed significant association with CV outcomes. VEGF-D was most strongly associated with CV death (P = 3.73e-05, HR 1.892 [1.419, 2.522]). Genome-wide significant associations with VEGF-D levels were identified at the VEGFD locus on chromosome Xp22. MR analyses of the combined top ranked SNPs (GWAS P-values; rs192812042, P = 5.82e-20; rs234500, P = 1.97e-14) demonstrated a significant effect on CV mortality [P = 0.0257, HR 1.81 (1.07, 3.04) per increase of one unit in log VEGF-D].

CONCLUSION

This is the first large-scale cohort study to demonstrate that both VEGF-D plasma levels and VEGFD genetic variants are independently associated with CV outcomes in patients with ACS and CCS. Measurements of VEGF-D levels and/or VEGFD genetic variants may provide incremental prognostic information in patients with ACS and CCS.

VEGF-D-mediated signaling in tendon cells is involved in degenerative processes

Vascular endothelial growth factor (VEGF) signaling is crucial for a large variety of cellular processes, not only related to angiogenesis but also in nonvascular cell types. We have previously shown that controlling angiogenesis by reducing VEGF-A signaling positively affects tendon healing. We now hypothesize that VEGF signaling in non-endothelial cells may contribute to tendon pathologies. By immunohistochemistry we show that VEGFR1, VEGFR2, and VEGFR3 are expressed in murine and human tendon cells in vivo. In a rat Achilles tendon defect model we show that VEGFR1, VEGFR3, and VEGF-D expression are increased after injury. On cultured rat tendon cells we show that VEGF-D stimulates cell proliferation in a dose-dependent manner; the specific VEGFR3 inhibitor SAR131675 reduces cell proliferation and cell migration. Furthermore, activation of VEGFR2 and -3 in tendon-derived cells affects the expression of mRNAs encoding extracellular matrix and matrix remodeling proteins. Using explant model systems, we provide evidence, that VEGFR3 inhibition prevents biomechanical deterioration in rat tail tendon fascicles cultured without load and attenuates matrix damage if exposed to dynamic overload in a bioreactor system. Together, these results suggest a strong role of tendon cell VEGF signaling in mediation of degenerative processes. These findings give novel insight into tendon cell biology and may pave the way for novel treatment options for degenerative tendon diseases.

The Role of the VEGF Family in Coronary Heart Disease

The vascular endothelial growth factor (VEGF) family, the regulator of blood and lymphatic vessels, is mostly investigated in the tumor and ophthalmic field. However, the functions it enjoys can also interfere with the development of atherosclerosis (AS) and further diseases like coronary heart disease (CHD). The source, regulating mechanisms including upregulation and downregulation, target cells/tissues, and known functions about VEGF-A, VEGF-B, VEGF-C, and VEGF-D are covered in the review. VEGF-A can regulate angiogenesis, vascular permeability, and inflammation by binding with VEGFR-1 and VEGFR-2. VEGF-B can regulate angiogenesis, redox, and apoptosis by binding with VEGFR-1. VEGF-C can regulate inflammation, lymphangiogenesis, angiogenesis, apoptosis, and fibrogenesis by binding with VEGFR-2 and VEGFR-3. VEGF-D can regulate lymphangiogenesis, angiogenesis, fibrogenesis, and apoptosis by binding with VEGFR-2 and VEGFR-3. These functions present great potential of applying the VEGF family for treating CHD. For instance, angiogenesis can compensate for hypoxia and ischemia by growing novel blood vessels. Lymphangiogenesis can degrade inflammation by providing exits for accumulated inflammatory cytokines. Anti-apoptosis can protect myocardium from impairment after myocardial infarction (MI). Fibrogenesis can promote myocardial fibrosis after MI to benefit cardiac recovery. In addition, all these factors have been confirmed to keep a link with lipid metabolism, the research about which is still in the early stage and exact mechanisms are relatively obscure. Because few reviews have been published about the summarized role of the VEGF family for treating CHD, the aim of this review article is to present an overview of the available evidence supporting it and give hints for further research.

Complex Interplay of Genes Underlies Invasiveness in Fibrosarcoma Progression Model

Sarcomas are a heterogeneous group of mesenchymal tumours, with a great variability in their clinical behaviour. While our knowledge of sarcoma initiation has advanced rapidly in recent years, relatively little is known about mechanisms of sarcoma progression. JUN-murine fibrosarcoma progression series consists of four sarcoma cell lines, JUN-1, JUN-2, JUN-2fos-3, and JUN-3. JUN-1 and -2 were established from a single tumour initiated in a H2K/v-jun transgenic mouse, JUN-3 originates from a different tumour in the same animal, and JUN-2fos-3 results from a targeted in vitro transformation of the JUN-2 cell line. The JUN-1, -2, and -3 cell lines represent a linear progression from the least transformed JUN-2 to the most transformed JUN-3, with regard to all the transformation characteristics studied, while the JUN-2fos-3 cell line exhibits a unique transformation mode, with little deregulation of cell growth and proliferation, but pronounced motility and invasiveness. The invasive sarcoma sublines JUN-2fos-3 and JUN-3 show complex metabolic profiles, with activation of both mitochondrial oxidative phosphorylation and glycolysis and a significant increase in spared respiratory capacity. The specific transcriptomic profile of invasive sublines features very complex biological relationships across the identified genes and proteins, with accentuated autocrine control of motility and angiogenesis. Pharmacologic inhibition of one of the autocrine motility factors identified, Ccl8, significantly diminished both motility and invasiveness of the highly transformed fibrosarcoma cell. This progression series could be greatly valuable for deciphering crucial aspects of sarcoma progression and defining new prognostic markers and potential therapeutic targets.

Role of Cardiac Lymphatics in Myocardial Edema and Fibrosis: JACC Review Topic of the Week

The cardiac lymphatic network plays a key role in regulation of myocardial extracellular volume and immune cell homeostasis. In different pathological conditions cardiac lymphatics undergo significant remodeling, with insufficient lymphatic function and/or lymphangiogenesis leading to fluid accumulation and development of edema. Additionally, by modulating the reuptake of tissue-infiltrating immune cells, lymphatics regulate immune responses. Available evidence suggests that both edema and inadequate immune response resolution may contribute to extracellular matrix remodeling and interstitial myocardial fibrosis. Interestingly, stimulation of lymphangiogenesis has been shown to improve cardiac function and reduce the progression of myocardial fibrosis during heart failure development after myocardial infarction. This review goes through the available clinical and experimental data supporting a role for cardiac lymphatics in cardiac disease, focusing on the current evidence linking poor cardiac lymphatic transport to the fibrogenic process and discussing potential avenues for novel biomarkers and therapeutic targets to limit cardiac fibrosis and dysfunction.

Nerve Growth Factor (NGF) modulates in vitro induced myofibroblasts by highlighting a differential protein signature

We previously described the profibrogenic effect of NGF on conjunctival Fibroblasts (FBs) and its ability to trigger apoptosis in TGFβ1-induced myofibroblasts (myoFBs). Herein, cell apoptosis/signalling, cytokines' signature in conditioned media and inflammatory as well as angiogenic pathway were investigated. Experimental myoFBs were exposed to NGF (0.1-100 ng/mL), at defined time-point for confocal and biomolecular analysis. Cells were analysed for apoptotic and cell signalling activation in cell extracts and for some inflammatory and proinflammatory/angiogenic factors' activations. NGF triggered cJun overexpression and phospho-p65-NFkB nuclear translocation. A decreased Bcl2:Bax ratio and a significant expression of smad7 were confirmed in early AnnexinV-positive myoFBs. A specific protein signature characterised the conditioned media: a dose dependent decrease occurred for IL8, IL6 while a selective increase was observed for VEGF and cyr61 (protein/mRNA). TIMP1 levels were unaffected. Herein, NGF modulation of smad7, the specific IL8 and IL6 as well as VEGF and cyr61 modulation deserve more attention as opening to alternative approaches to counteract fibrosis.

Current Understanding of Circulating Biomarkers in Pulmonary Hypertension Due to Left Heart Disease

Pulmonary hypertension due to left heart disease (PH-LHD; Group 2), especially in the setting of heart failure with preserved ejection fraction (HFpEF), is the most frequent cause of PH. Despite its prevalence, no effective therapies for PH-LHD are available at present. This is largely due to the lack of a concise definition for hemodynamic phenotyping, existence of significant gaps in the understanding of the underlying pathology and the impact of associated comorbidities, as well as the absence of specific biomarkers that can aid in the early diagnosis and management of this challenging syndrome. Currently, B-type natriuretic peptide (BNP) and N-terminal proBNP (NT-proBNP) are guideline-recommended biomarkers for the diagnosis and prognosis of heart failure (HF) and PH. Endothelin-1 (ET-1), vascular endothelial growth factor-D (VEGF-D), and microRNA-206 have also been recently identified as new potential circulating biomarkers for patients with PH-LHD. In this review, we aim to present the current state of knowledge of circulating biomarkers that can be used to guide future research toward diagnosis, refine specific patient phenotype, and develop therapeutic approaches for PH-LHD, with a particular focus on PH-HFpEF. Potential circulating biomarkers identified in pre-clinical models of PH-LHD are also summarized here.

Distinct Characteristics of VEGF-D and VEGF-C to Predict Mortality in Patients With Suspected or Known Coronary Artery Disease

Background

VEGF‐D (vascular endothelial growth factor D) and VEGF‐C are secreted glycoproteins that can induce lymphangiogenesis and angiogenesis. They exhibit structural homology but have differential receptor binding and regulatory mechanisms. We recently demonstrated that the serum VEGF‐C level is inversely and independently associated with all‐cause mortality in patients with suspected or known coronary artery disease. We investigated whether VEGF‐D had distinct relationships with mortality and cardiovascular events in those patients.

Methods and Results

We performed a multicenter, prospective cohort study of 2418 patients with suspected or known coronary artery disease undergoing elective coronary angiography. The serum level of VEGF‐D was measured. The primary outcome was all‐cause death. The secondary outcomes were cardiovascular death and major adverse cardiovascular events defined as a composite of cardiovascular death, nonfatal myocardial infarction, and nonfatal stroke. During the 3‐year follow‐up, 254 patients died from any cause, 88 died from cardiovascular disease, and 165 developed major adverse cardiovascular events. After adjustment for possible clinical confounders, cardiovascular biomarkers (N‐terminal pro‐B‐type natriuretic peptide, cardiac troponin‐I, and high‐sensitivity C‐reactive protein), and VEGF‐C, the VEGF‐D level was significantly associated with all‐cause death and cardiovascular death but not with major adverse cardiovascular events.. Moreover, the addition of VEGF‐D, either alone or in combination with VEGF‐C, to the model with possible clinical confounders and cardiovascular biomarkers significantly improved the prediction of all‐cause death but not that of cardiovascular death or major adverse cardiovascular events. Consistent results were observed within patients over 75 years old.

Conclusions

In patients with suspected or known coronary artery disease undergoing elective coronary angiography, an elevated VEGF‐D value seems to independently predict all‐cause mortality.

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.

Molecular and Cellular Effect of Angiotensin 1-7 on Hypertensive Kidney Disease

BACKGROUND

Studies implicate that angiotensin 1-7 (Ang1-7) imparts protective effects in the kidney. However, its relevance in hypertensive kidney disease is not fully understood. The purpose of this study was to explore the role of Ang1-7 on renal damage/remodeling during hypertension and its potential underlying molecular-cellular mechanisms.

METHODS

Hypertension was induced in adult Sprague-Dawley rats by infusion of aldosterone (ALDO; 0.75 μg/hour) for 4 weeks with or without co-treatment of Ang1-7 (1 mg/kg/day). Untreated rats served as controls. Systolic blood pressure was monitored by tail-cuff technique. Renal fibrosis was evaluated by picrosirius red staining and renal collagen volume fraction was quantitated using imaging analyzing system. The expression of profibrotic factors [transforming growth factor-β1 (TGF-β1), platelet-derived growth factor-D (PDGF-D), fibroblast growth factor-1 (FGF-1), vascular endothelial growth factor-D (VEGF-D), and tissue inhibitors of metalloproteinases (TIMPs)] and free radical producing enzymes (inducible nitric oxide synthase and nicotinamide adenine dinucleotide phosphate [NADPH] oxidase) in the kidney were examined by reverse transcription-polymerase chain reaction and western blot. Renal oxidative stress was assessed by malondialdehyde (MDA) measurement.

RESULTS

Chronic ALDO infusion caused hypertension and hypertensive renal disease represented as glomerular damage/sclerosis. Ang1-7 co-treatment did not affect blood pressure in ALDO-treated rats, but significantly attenuated the glomerular damage/fibrosis. ALDO treatment significantly elevated renal expression of profibrogenic factors, including TGF-β1, TIMP-1/TIMP-2, FGF-1, PDGF-D, and VEGF-D, whereas Ang1-7 co-treatment significantly reduced renal TGF-β1, TIMP-1/TIMP-2, and FGF-1, but not PDGF-D and VEGF-D. Furthermore, ALDO infusion elevated NADPH oxidase (gp91phox) and MDA in the kidney, which was attenuated by Ang1-7 co-treatment.

CONCLUSIONS

Ang1-7 plays a protective role in the hypertensive kidney disease independent of blood pressure. The beneficial effects of Ang1-7 are likely mediated via suppressing TGF-β/FGF-1 pathways and oxidative stress.

Comparative gene array analyses of severe elastic fiber defects in late embryonic and newborn mouse aorta

Elastic fibers provide reversible elasticity to the large arteries and are assembled during development when hemodynamic forces are increasing. Mutations in elastic fiber genes are associated with cardiovascular disease. Mice lacking expression of the elastic fiber genes elastin ( Eln-/-), fibulin-4 ( Efemp2-/-), or lysyl oxidase ( Lox-/-) die at birth with severe cardiovascular malformations. All three genetic knockout models have elastic fiber defects, aortic wall thickening, and arterial tortuosity. However, Eln-/- mice develop arterial stenoses, while Efemp2-/- and Lox-/- mice develop ascending aortic aneurysms. We performed comparative gene array analyses of these three genetic models for two vascular locations and developmental stages to determine differentially expressed genes and pathways that may explain the common and divergent phenotypes. We first examined arterial morphology and wall structure in newborn mice to confirm that the lack of elastin, fibulin-4, or lysyl oxidase expression provided the expected phenotypes. We then compared gene expression levels for each genetic model by three-way ANOVA for genotype, vascular location, and developmental stage. We found three genes upregulated by genotype in all three models, Col8a1, Igfbp2, and Thbs1, indicative of a common response to severe elastic fiber defects in developing mouse aorta. Genes that are differentially regulated by vascular location or developmental stage in all three models suggest mechanisms for location or stage-specific disease pathology. Comparison of signaling pathways enriched in all three models shows upregulation of integrins and matrix proteins involved in early wound healing, but not of mature matrix molecules such as elastic fiber proteins or fibrillar collagens.

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.

Increased vascular endothelial growth factor D is associated with atrial fibrillation and ischaemic stroke

OBJECTIVE

Vascular endothelial growth factor D (VEGF-D) has important functions in lymphangiogenesis and angiogenesis. High plasma levels of VEGF-D have been associated with incidence of heart failure. The association of VEGF-D with atrial fibrillation (AF) and stroke is unclear and we hypothesised that VEGF-D could also be associated with incidence of AF and ischaemic stroke.

METHODS

VEGF-D was measured in fasting blood samples of 4689 subjects (40% men) without a history of AF from the Malmö Diet and Cancer Study, a prospective, population-based study in Sweden. Median age was 58 years (range 46-68). Cox regression analyses, adjusted for multiple risk factors, was used to assess AF and ischaemic stroke risk in relation to VEGF-D levels.

RESULTS

During a median follow-up time of 20.6 years, there were 637 cases of incident AF and 322 cases of first ischaemic stroke. After adjustment, VEGF-D was significantly associated with AF (HR 1.13(95% CI 1.04 to 1.23) per 1 SD increase) and ischaemic stroke (HR 1.14(95% CI 1.02 to 1.28) per 1 SD). The association with ischaemic stroke was explained by an increased incidence of AF-related stroke. HRs per 1 SD were 1.34 (95% CI 1.04 to 1.71) for AF-related ischaemic stroke and 1.04 (95% CI 0.90 to 1.19) for ischaemic stroke without AF.

CONCLUSIONS

Increased VEGF-D concentrations were associated with AF and ischaemic stroke. The relationship with ischaemic stroke was more pronounced in subjects with a diagnosis of AF.

Sustained β-AR stimulation induces synthesis and secretion of growth factors in cardiac myocytes that affect on cardiac fibroblast activation

Paracrine factors, including growth factors and cytokines, released from cardiac myocytes following β-adrenergic receptor (β-AR) stimulation regulate cardiac fibroblasts. Activated cardiac fibroblasts have the ability to increase collagen synthesis, cell proliferation and myofibroblast differentiation, leading to cardiac fibrosis. However, it is unknown which β-AR subtypes and signaling pathways mediate the upregulation of paracrine factors in cardiac myocytes. In this study, we demonstrated that sustained stimulation of β-ARs significantly induced synthesis and secretion of growth factors, including connective tissue growth factor (CTGF) and vascular endothelial growth factor (VEGF), via the cAMP-dependent and protein kinase A (PKA)-dependent pathways. In addition, isoproterenol (ISO)-mediated synthesis and secretion of CTGF and VEGF through the β₁-AR and β₂-AR subtypes. Paracrine factors released by cardiac myocytes following sustained β-AR stimulation are necessary for the induction of cell proliferation and synthesis of collagen I, collagen III and α-smooth muscle actin (α-SMA) in cardiac fibroblasts, confirming that β-AR overstimulation of cardiac myocytes induces cardiac fibrosis by releasing several paracrine factors. These effects can be antagonized by β-blockers, including atenolol, metoprolol, and propranolol. Thus, the use of β-blockers may have beneficial effects on the treatment of myocardial fibrosis in patients with heart failure.

Vascular endothelial growth factor-D modulates oxidant-antioxidant balance of human vascular endothelial cells

Vascular endothelial growth factor‐D (VEGF‐D) is an angiogenic and lymphangiogenic glycoprotein that facilitates tumour growth and distant organ metastasis. Our previous studies showed that VEGF‐D stimulates the expression of proteins involved in cell–matrix interactions and promoting the migration of endothelial cells. In this study, we focused on the redox homoeostasis of endothelial cells, which is significantly altered in the process of tumour angiogenesis. Our analysis revealed up‐regulated expression of proteins that form the antioxidant barrier of the cell in VEGF‐D‐treated human umbilical endothelial cells and increased production of reactive oxygen and nitrogen species in addition to a transient elevation in the total thiol group content. Despite a lack of changes in the total antioxidant capacity, modification of the antioxidant barrier induced by VEGF‐D was sufficient to protect cells against the oxidative stress caused by hypochlorite and paraquat. These results suggest that exogenous stimulation of endothelial cells with VEGF‐D induces an antioxidant response of cells that maintains the redox balance. Additionally, VEGF‐D‐induced changes in serine/threonine kinase mTOR shuttling between the cytosol and nucleus and its increased phosphorylation at Ser‐2448, lead us to the conclusion that the observed shift in redox balance is regulated via mTOR kinase signalling.

Bilateral sympathectomy improves postinfarction left ventricular remodeling and function

OBJECTIVES

To evaluate the influence of bilateral or left sympathectomy on left ventricular remodeling and function after myocardial infarction in rats.

METHODS

Myocardial infarction was induced in rats by ligation of the left anterior descending coronary. Seven days later, rats were divided into 4 groups: the myocardial infarction, myocardial infarction with left sympathectomy, myocardial infarction with bilateral sympathectomy, and sham groups. After 8 weeks, left ventricular function was evaluated with the use of a pressure-volume conductance catheter under steady-state conditions and pharmacological stress. Infarct size and extracellular matrix fibrosis were evaluated, and cardiac matrix metalloproteinases and myocardial inflammatory markers were analyzed.

RESULTS

The myocardial infarction and left sympathectomy group had an increased end diastolic volume, whereas the bilateral sympathectomy group had a mean end-diastolic volume similar to that of the sham group (P < .002). Significant reduction in ejection fraction was observed in the myocardial infarction and left sympathectomy group, whereas it was preserved after bilateral sympathectomy (P < .001). In response to dobutamine, left ventricular contractility increased in sham rats, rising stroke work, cardiac output, systolic volume, end-diastolic volume, ejection fraction, and dP/dt max. Only bilateral sympathectomy rats had significant increases in ejection fraction (P < .001) with dobutamine. Fibrotic tissue and matrix metalloproteinase expression decreased in the bilateral sympathectomy group compared to that in the myocardial infarction group (P < .001) and was associated with left ventricular wall thickness maintenance and better apoptotic markers in noninfarcted myocardium.

CONCLUSIONS

Bilateral sympathectomy effectively attenuated left ventricular remodeling and preserved systolic function after myocardial infarction induction in rats.