TGF-betas and TGF-beta receptors in atherosclerosis

Advanced biosensors for nanomaterial-based detection of transforming growth factor alpha and beta, a class of major polypeptide regulators

Transforming growth factors (TGFs) regulate several cellular processes including, differentiation, growth, migration, extracellular matrix production, and apoptosis. TGF alpha (TGF-α) is a heterogeneous molecule containing 160 amino acid residues. It is a potent angiogenesis promoter that is activated by JAK-STAT signaling. Whereas TGF beta (TGF-β) consists of 390-412 amino acids. Smad and non-Smad signaling both occur in TGF beta. It is linked to immune cell activation, differentiation, and proliferation. It also triggers pre-apoptotic responses and inhibits cell proliferation. Both growth factors have a promising role in the development and homeostasis of tissues. Defects such as autoimmune diseases and cancer develop mechanisms to modulate checkpoints of the immune system resulting in altered growth factors profile. An accurate amount of these growth factors is essential for normal functioning, but an exceed or fall behind the normal level is alarming as it is linked to several disorders. This demands techniques for TGF-α and TGF-β profiling to effectively diagnose diseases, monitor their progression, and assess the efficacy of immunotherapeutic drugs. Quantitative detection techniques including the emergence of biosensing technology seem to accomplish the purpose. Until the present time, few biosensors have been designed in the context of TGF-α and TGF-β for disease detection, analyzing receptor binding, and interaction with carriers. In this paper, we have reviewed the physiology of transforming growth factor alpha and beta, including the types, structure, function, latent/active forms, signaling, and defects caused. It involves the description of biosensors on TGF-α and TGF-β, advances in technology, and future perspectives.

Evidence Accumulates: Patients with Ascending Aneurysms Are Strongly Protected from Atherosclerotic Disease

Ascending thoracic aortic aneurysms may be fatal upon rupture or dissection and remain a leading cause of death in the developed world. Understanding the pathophysiology of the development of ascending thoracic aortic aneurysms may help reduce the morbidity and mortality of this disease. In this review, we will discuss our current understanding of the protective relationship between ascending thoracic aortic aneurysms and the development of atherosclerosis, including decreased carotid intima-media thickness, low-density lipoprotein levels, coronary and aortic calcification, and incidence of myocardial infarction. We also propose several possible mechanisms driving this relationship, including matrix metalloproteinase proteins and transforming growth factor-β.

Therapeutic potential of human umbilical cord mesenchymal stem cells on aortic atherosclerotic plaque in a high-fat diet rabbit model

BACKGROUND

Atherosclerosis (AS) is a complex disease caused in part by dyslipidemia and chronic inflammation. AS is associated with serious cardiovascular disease and remains the leading cause of mortality worldwide. Mesenchymal stem cells (MSCs) have evolved as an attractive therapeutic agent in various diseases including AS. Human umbilical cord MSCs (UCSCs) have been used in cell therapy trials due to their ability to differentiate and proliferate. The present study aimed to investigate the effect of UCSCs treatment on atherosclerotic plaque formation and the progression of lesions in a high-fat diet rabbit model.

METHODS

Rabbits were fed a high-fat diet and then randomly divided into three groups: control, model, and treatment groups. Rabbits in the treatment group were injected with UCSCs (6 × 106 in 500 μL phosphate buffered saline) after 1 month of high-fat diet, once every 2 weeks, for 3 months. The model group was given PBS only. We analyzed serum biomarkers, used ultrasound and histopathology to detect arterial plaques and laser Doppler imaging to measure peripheral blood vessel blood filling, and analyzed the intestinal flora and metabolism.

RESULTS

Histological analysis showed that the aortic plaque area was significantly reduced in the treatment group. We also found a significant decrease in macrophage accumulation and apoptosis, an increase in expression of scavenger receptors CD36 and SRA1, a decrease in uptake of modified low-density protein (ox-LDL), and a decrease in levels of pro-inflammatory cytokines interleukin (IL)-6 and tumor necrosis factor (TNF)-α following UCSCs treatment. We also found that anti-inflammatory cytokines IL-10 and transforming growth factor (TGF)-β expression increased in the aorta atherosclerotic plaque of the treatment group. UCSCs treatment improved the early peripheral blood filling, reduced the serum lipid level, and inhibited inflammation progression by regulating the intestinal flora dysbiosis caused by the high-fat diet. More specifically, levels of the microbiota-dependent metabolite trimethylamine-N-oxide (TMAO) were down-regulated in the treatment group.

CONCLUSIONS

UCSCs treatment alleviated atherosclerotic plaque burden by reducing inflammation, regulating the intestinal flora and TMAO levels, and repairing the damaged endothelium.

Disease-Relevant Single Cell Photonic Signatures Identify S100β Stem Cells and their Myogenic Progeny in Vascular Lesions

A hallmark of subclinical atherosclerosis is the accumulation of vascular smooth muscle cell (SMC)-like cells leading to intimal thickening and lesion formation. While medial SMCs contribute to vascular lesions, the involvement of resident vascular stem cells (vSCs) remains unclear. We evaluated single cell photonics as a discriminator of cell phenotype in vitro before the presence of vSC within vascular lesions was assessed ex vivo using supervised machine learning and further validated using lineage tracing analysis. Using a novel lab-on-a-Disk(Load) platform, label-free single cell photonic emissions from normal and injured vessels ex vivo were interrogated and compared to freshly isolated aortic SMCs, cultured Movas SMCs, macrophages, B-cells, S100β⁺ mVSc, bone marrow derived mesenchymal stem cells (MSC) and their respective myogenic progeny across five broadband light wavelengths (λ465 - λ670 ± 20 nm). We found that profiles were of sufficient coverage, specificity, and quality to clearly distinguish medial SMCs from different vascular beds (carotid vs aorta), discriminate normal carotid medial SMCs from lesional SMC-like cells ex vivo following flow restriction, and identify SMC differentiation of a series of multipotent stem cells following treatment with transforming growth factor beta 1 (TGF- β1), the Notch ligand Jagged1, and Sonic Hedgehog using multivariate analysis, in part, due to photonic emissions from enhanced collagen III and elastin expression. Supervised machine learning supported genetic lineage tracing analysis of S100β⁺ vSCs and identified the presence of S100β⁺vSC-derived myogenic progeny within vascular lesions. We conclude disease-relevant photonic signatures may have predictive value for vascular disease.

Integrating systematic biological and proteomics strategies to explore the pharmacological mechanism of danshen yin modified on atherosclerosis

This research utilized the systematic biological and proteomics strategies to explore the regulatory mechanism of Danshen Yin Modified (DSYM) on atherosclerosis (AS) biological network. The traditional Chinese medicine database and HPLC was used to find the active compounds of DSYM, Pharmmapper database was used to predict potential targets, and OMIM database and GeneCards database were used to collect AS targets. String database was utilized to obtain the other protein of proteomics proteins and the protein-protein interaction (PPI) data of DSYM targets, AS genes, proteomics proteins and other proteins. The Cytoscape 3.7.1 software was utilized to construct and analyse the network. The DAVID database is used to discover the biological processes and signalling pathways that these proteins aggregate. Finally, animal experiments and proteomics analysis were used to further verify the prediction results. The results showed that 140 active compounds, 405 DSYM targets and 590 AS genes were obtained, and 51 differentially expressed proteins were identified in the DSYM-treated ApoE-/- mouse AS model. A total of 4 major networks and a number of their derivative networks were constructed and analysed. The prediction results showed that DSYM can regulate AS-related biological processes and signalling pathways. Animal experiments have also shown that DSYM has a therapeutic effect on ApoE-/-mouse AS model (P < .05). Therefore, this study proposed a new method based on systems biology, proteomics, and experimental pharmacology, and analysed the pharmacological mechanism of DSYM. DSYM may achieve therapeutic effects by regulating AS-related signalling pathways and biological processes found in this research.

Switching of vascular cells towards atherogenesis, and other factors contributing to atherosclerosis: a systematic review

Background

Onset, development and progression of atherosclerosis are complex multistep processes. Many aspects of atherogenesis are not yet properly known. This study investigates the changes in vasculature that contribute to switching of vascular cells towards atherogenesis, focusing mainly on ageing.

Methods

Databases including PubMed, MEDLINE and Google Scholar were searched for published articles without any date restrictions, involving atherogenesis, vascular homeostasis, aging, gene expression, signaling pathways, angiogenesis, vascular development, vascular cell differentiation and maintenance, vascular stem cells, endothelial and vascular smooth muscle cells.

Results

Atherogenesis is a complex multistep process that unfolds in a sequence. It is caused by alterations in: epigenetics and genetics, signaling pathways, cell circuitry, genome stability, heterotypic interactions between multiple cell types and pathologic alterations in vascular microenvironment. Such alterations involve pathological changes in: Shh, Wnt, NOTCH signaling pathways, TGF beta, VEGF, FGF, IGF 1, HGF, AKT/PI3K/ mTOR pathways, EGF, FOXO, CREB, PTEN, several apoptotic pathways, ET - 1, NF-κB, TNF alpha, angiopoietin, EGFR, Bcl - 2, NGF, BDNF, neurotrophins, growth factors, several signaling proteins, MAPK, IFN, TFs, NOs, serum cholesterol, LDL, ephrin, its receptor pathway, HoxA5, Klf3, Klf4, BMPs, TGFs and others.This disruption in vascular homeostasis at cellular, genetic and epigenetic level is involved in switching of the vascular cells towards atherogenesis. All these factors working in pathologic manner, contribute to the development and progression of atherosclerosis.

Conclusion

The development of atherosclerosis involves the switching of gene expression towards pro-atherogenic genes. This happens because of pathologic alterations in vascular homeostasis. When pathologic alterations in epigenetics, genetics, regulatory genes, microenvironment and vascular cell biology accumulate beyond a specific threshold, then the disease begins to express itself phenotypically. The process of biological ageing is one of the most significant factors in this aspect as it is also involved in the decline in homeostasis, maintenance and integrity.The process of atherogenesis unfolds sequentially (step by step) in an interconnected loop of pathologic changes in vascular biology. Such changes are involved in 'switching' of vascular cells towards atherosclerosis.

Circular RNA circ_0003204 inhibits proliferation, migration and tube formation of endothelial cell in atherosclerosis via miR-370-3p/TGFβR2/phosph-SMAD3 axis

BACKGROUND

Circular RNAs (circRNAs) represent a class of non-coding RNAs (ncRNAs) which are widely expressed in mammals and tissue-specific, of which some could act as critical regulators in the atherogenesis of cerebrovascular disease. However, the underlying mechanisms by which circRNA regulates the ectopic phenotype of endothelial cells (ECs) in atherosclerosis remain largely elusive.

METHODS

CCK-8, transwell, wound healing and Matrigel assays were used to assess cell viability, migration and tube formation. QRT-qPCR and Immunoblotting were used to examine targeted gene expression in different groups. The binding sites of miR-370-3p (miR-370) with TGFβR2 or hsa_circ_0003204 (circ_0003204) were predicted using a series of bioinformatic tools, and validated using dual luciferase assay and RNA immunoprecipitation (RIP) assay. The localization of circ_0003204 and miR-370 in ECs were investigated by fluorescence in situ hybridization (FISH). Gene function and pathways were enriched through Metascape and gene set enrichment analysis (GSEA). The association of circ_0003204 and miR-370 in extracellular vesicles (EVs) with clinical characteristics of patients were investigated using multiple statistical analysis.

RESULTS

Circ_0003204, mainly located in the cytoplasm of human aorta endothelial cells (HAECs), was upregulated in the ox-LDL-induced HAECs. Functionally, the ectopic expression of circ_0003204 inhibited proliferation, migration and tube formation of HAECs exposed to ox-LDL. Mechanically, circ_0003204 could promote protein expression of TGFβR2 and its downstream phosph-SMAD3 through sponging miR-370, and miR-370 targeted the 3' untranslated region (UTR) of TGFβR2. Furthermore, the expression of circ_0003204 in plasma EVs was upregulated in the patients with cerebral atherosclerosis, and represented a potential biomarker for diangnosis and prognosis of cerebrovascular atherogenesis.

CONCLUSIONS

Circ_0003204 could act as a novel stimulator for ectopic endothelial inactivation in atherosclerosis and a potential biomarker for cerebral atherosclerosis.

Inhibition of Vascular Calcification

Objective- Vascular calcification is a major risk factor for rupture of atherosclerotic plaques. High expression of BMP2 (bone morphogenetic protein 2) in lesions suggests its importance in vascular calcification during atherosclerosis. Teniposide is a Topo II (DNA topoisomerase II) inhibitor and is used for cancer treatment. Previously, we reported that teniposide activated macrophage ABCA1 (ATP-binding cassette transporter A1) expression and free cholesterol efflux indicating Topo II inhibitors may demonstrate antiatherogenic properties. Herein, we investigated the effects of teniposide on the development of atherosclerosis and vascular calcification in apoE^-/- (apoE deficient) mice. Approach and Results- apoE^-/- mice were fed high-fat diet containing teniposide for 16 weeks, or prefed high-fat diet for 12 weeks followed by high-fat diet containing teniposide for 4 weeks. Atherosclerosis and vascular calcification were determined. Human aortic smooth muscle cells were used to determine the mechanisms for teniposide-inhibited vascular calcification. Teniposide reduced atherosclerotic lesions. It also substantially reduced vascular calcification without affecting bone structure. Mechanistically, teniposide reduced vascular calcification by inactivating BMP2/(pi-Smad1/5/8 [mothers against decapentaplegic homolog 1, 5, and 8])/RUNX2 (runt-related transcription factor 2) axis in a p53-dependent manner. Furthermore, activated miR-203-3p by teniposide functioned as a link between activated p53 expression and inhibited BMP2 expression in inhibition of calcification. Conclusions- Our study demonstrates that teniposide reduces vascular calcification by regulating p53-(miR-203-3p)-BMP2 signaling pathway, which contributes to the antiatherogenic properties of Topo II inhibitors.

Smooth muscle cell-specific Tgfbr1 deficiency attenuates neointimal hyperplasia but promotes an undesired vascular phenotype for injured arteries

Neointimal hyperplasia (NIH) and inward wall remodeling cause arterial restenosis and failure of bypass vein grafts. Previous studies from our group suggest that transforming growth factor (TGF) β promotes these pathologies via regulating cell kinetics at the early stage and matrix metabolism at the late stage. Although these temporal TGFβ effects may result from its signaling in different cell groups, the responsible cell type has not been identified. In the current study, we evaluated the effect of smooth muscle cell (SMC)‐specific TGFβ signaling through its type I receptor TGFBR1 on NIH and wall remodeling of the injured femoral arteries (FAs). An inducible Cre/loxP system was employed to delete SMC Tgfbr1 (Tgfbr1^iko). Mice not carrying the Cre allele (Tgfbr1^f/f) served as controls. The injured FAs were evaluated on d3, d7, and d28 postoperatively. Tgfbr1^iko attenuated NIH by 92%, but had insignificant influence on arterial caliber when compared with Tgfbr1^f/f controls on d28. This attenuation correlated with greater cellularity and reduced collagen content. Compared with Tgfbr1^f/fFAs, however, Tgfbr1^ikoFAs exhibited persistent neointimal cell proliferation and cell apoptosis, with both events at a greater rate on d28. Tgfbr1^ikoFAs additionally contained fewer SMCs and more inflammatory infiltrates in the neointima and displayed a thicker adventitia than did Tgfbr1^f/fFAs. More MMP9 proteins were detected in the adventitia of Tgfbr1^ikoFAs than in that of Tgfbr1^f/f controls. Our results suggest that disruption of SMC Tgfbr1 inhibits arterial NIH in the short term, but the overall vascular phenotype may not favor long‐term performance of the injured arteries.

New Insights into the Role of Inflammation in the Pathogenesis of Atherosclerosis

Atherosclerosis is a chronic inflammatory disease characterized by the accumulation of lipids, smooth muscle cell proliferation, cell apoptosis, necrosis, fibrosis, and local inflammation. Immune and inflammatory responses have significant effects on every phase of atherosclerosis, and increasing evidence shows that immunity plays a more important role in atherosclerosis by tightly regulating its progression. Therefore, understanding the relationship between immune responses and the atherosclerotic microenvironment is extremely important. This article reviews existing knowledge regarding the pathogenesis of immune responses in the atherosclerotic microenvironment, and the immune mechanisms involved in atherosclerosis formation and activation.

Is plasminogen activator inhibitor-1 a physiological bottleneck bridging major depressive disorder and cardiovascular disease?

Major depressive disorder (MDD) is estimated to affect one in twenty people worldwide. MDD is highly comorbid with cardiovascular disease (CVD), itself one of the single largest causes of mortality worldwide. A number of pathological changes observed in MDD are believed to contribute to the development of cardiovascular disease, although no single mechanism has been identified. There are also no biological markers capable of predicting the future risk of developing heart disease in depressed individuals. Plasminogen activator inhibitor-1 (PAI-1) is a prothrombotic plasma protein secreted by endothelial tissue and has long been implicated in CVD. An expanding body of literature has recently implicated it in the pathogenesis of major depressive disorder as well. In this study, we review candidate pathways implicating MDD in CVD and consider how PAI-1 might act as a mediator by which MDD induces CVD development: chiefly through sleep disruption, adiposity, brain-derived neurotrophic factor (BDNF) metabolism, systemic inflammation and hypothalamic-pituitary-adrenal (HPA)-axis dysregulation. As both MDD and CVD are more prevalent in women than in men, and incidence of either condition is dramatically increased during reproductive milestones, we also explore hormonal and sex-specific associations between MDD, PAI-1 and CVD. Of special interest is the role PAI-1 plays in perinatal depression and in cardiovascular complications of pregnancy. Finally, we propose a theoretical model whereby PAI-1 might serve as a useful biomarker for CVD risk in those with depression, and as a potential target for future treatments.

Polymorphisms of TGFβ-1 and TGFBR2 in relation to coronary artery disease in a Chinese population

BACKGROUND AND AIM

TGF-β1 has been previously reported to be involved in the pathogenesis of atherosclerosis. The aim of the present study was to assess whether functional gene polymorphisms of TGF-β1 and its key receptor TGF-β receptor type II (TGFBR2) contribute as risk factors to the onset and severity of atherosclerotic coronary artery disease (CAD).

DESIGN AND METHODS

A total of 605 patients who underwent angiography for suspected CAD were prospectively recruited to this study. Coronary stenosis severity was assessed by the number of narrowed coronary vessels and the Gensini score. Among them, 502 patients had documented CAD, and 103 patients without documented CAD served as non-CAD controls. All patients were genotyped for one TGF-β1 polymorphism (rs1800470 (+T29C)) and two TGFBR2 polymorphisms (rs6785385 (-3779A/G), rs764522 (-1444C/G)) by polymerase chain reaction-restriction fragment length polymorphism and confirmed by direct sequencing.

RESULTS

No significant difference in the frequency for either polymorphism was found between CAD and control patients. Neither TGFBR2 rs6785385 (-3779A/G) nor rs764522 (-1444C/G) gene polymorphisms were associated with the severity of CAD (P>0.05). In male CAD patients, polymorphisms at TGF-β1 rs1800470 (+T29C) were, however, associated with the severity of CAD. The T allele frequency was significantly and positively correlated with the number of narrowed coronary arteries (three or more vessels: 49.3%, two vessels: 44.1%, one vessel: 36.9%) (P=0.039). Gensini scores in patients with the TT, CT, and CC genotype were 34.33±2.23, 32.06±4.79, and 26.90±3.83, respectively (P<0.05). In multiple linear regression analysis, the T allele of TGF-β1 polymorphism was independently correlated with the Gensini score (β=0.131).

CONCLUSION

TGF-β1 T29C gene polymorphism may be associated with severity of CAD in male patients. TGFBR2 polymorphisms may not determine the genetic susceptibility to CAD.

Coding Microsatellite Frameshift Mutations Accumulate in Atherosclerotic Carotid Artery Lesions: Evaluation of 26 Cases and Literature Review

Somatic DNA alterations are known to occur in atherosclerotic carotid artery lesions; however, their significance is unknown. The accumulation of microsatellite mutations in coding DNA regions may reflect a deficiency of the DNA mismatch repair (MMR) system. Alternatively, accumulation of these coding microsatellite mutations may indicate that they contribute to the pathology. To discriminate between these two possibilities, we compared the mutation frequencies in coding microsatellites (likely functionally relevant) with those in noncoding microsatellites (likely neutral). Genomic DNA was isolated from carotid endarterectomy (CEA) specimens of 26 patients undergoing carotid surgery and from 15 nonatherosclerotic control arteries. Samples were analyzed by DNA fragment analysis for instability at three noncoding (BAT25, BAT26, CAT25) and five coding (AIM2, ACVR2, BAX, CASP5, TGFBR2) microsatellite loci, with proven validity for detection of microsatellite instability in neoplasms. We found an increased frequency of coding microsatellite mutations in CEA specimens compared with control specimens (34.6 versus 0%; p = 0.0013). Five CEA specimens exhibited more than one frameshift mutation, and ACVR2 and CASP5 were affected most frequently (5/26 and 6/26). Moreover, the rate of coding microsatellite alterations (15/130) differed significantly from that of noncoding alterations (0/78) in CEA specimens (p = 0.0013). In control arteries, no microsatellite alterations were observed, neither in coding nor in noncoding microsatellite loci. In conclusion, the specific accumulation of coding mutations suggests that these mutations play a role in the pathogenesis of atherosclerotic carotid lesions, since the absence of mutations in noncoding microsatellites argues against general microsatellite instability, reflecting MMR deficiency.

Ascending thoracic aortic aneurysms protect against myocardial infarctions

There has been increasing evidence that ascending thoracic aortic aneurysms (TAAs) protect against atherosclerosis. However, there have been no studies examining the relationship between ascending TAAs and clinical endpoints of atherosclerosis, such as stroke or peripheral arterial disease. In this study, we aim to characterize the relationship between TAAs and a specific clinical endpoint of atherosclerosis, myocardial infarction (MI). We compared prevalence of coronary artery disease (CAD) and MIs in 487 patients who underwent surgical repair for ascending TAAs to 500 control patients who did not have an ascending TAA. Multivariate binary logistic regression was used to calculate the odds of having MI if a patient had an ascending TAA versus any of several MI risk factors. There was a significantly lower prevalence of CAD and MI in the ascending TAA group than in the control TAA group. The odds of having a MI if a patient had a MI risk factor were all > 1 (more likely to have a MI), with the lowest statistically significant odds ratio being 1.54 (age; p = 0.001) and the highest being 14.9 (family history of MI; p < 0.001). The odds ratio of having a MI if a patient had an ascending TAA, however, was near 0 at 0.05 (p < 0.001). This study provides evidence that ascending TAAs protect against MIs, adding further support to the hypothesis that ascending TAAs protect against atherosclerotic disease.

Glycosaminoglycan metabolism defects and atherosclerosis: frequent association of endothelial dysfunction in patients with Mucopolysaccharidosis

Cardiovascular lesions, including coronary artery stenosis, are frequently associated and can cause sudden death in patients with genetic defects of glycosaminoglycan (GAG) metabolism. Early diagnosis of coronary artery lesions is difficult, although potentially lifesaving. Histopathological similarities between atherosclerotic changes in adults and in patients with genetic GAG metabolism defects have been known. Atherosclerosis is the result of a complex process involving metabolism of GAGs and proteoglycans preceded by endothelial dysfunction as a key event. Decreased nitric oxide (NO) bioavailability is considered the hallmark of endothelial dysfunction. Reduced NO synthase (NOS) has been reported in atherosclerotic arteries. Impairment in reactive hyperemia-digital peripheral arterial tonometry (RH-PAT) with EndoPAT has been validated to correlate coronary microvascular function in patients with atherosclerosis. RH-PAT is thought to reflect endothelial NO production. Immunohistological staining of endothelial NOS was performed in the stenotic lesions in the coronary artery of a 3-year-old patient with Mucopolysaccharidosis-I, showing decreased activities. This prompted a study to measure endothelial function in patients with GAG metabolism defects for early diagnosis of endothelial dysfunction in the coronary arteries as an early sign of coronary artery changes. Evaluation by RH-PAT in 30 patients with variable genetic defects in GAG metabolism revealed significantly decreased Reactive Hyperemia Indexes compared with 12 controls. Evaluation of endothelial function with RH-PAT in patients with GAG metabolism defects may detect coronary artery lesions that can be underdiagnosed by the other measures such as coronary angiography. Use of this method may prove vital in the management of patients with GAG metabolism defects.

Endothelial cell energy metabolism, proliferation, and apoptosis in pulmonary hypertension

Pulmonary arterial hypertension (PAH) is a fatal disease characterized by impaired regulation of pulmonary hemodynamics and excessive growth and dysfunction of the endothelial cells that line the arteries in PAH lungs. Establishment of methods for culture of pulmonary artery endothelial cells from PAH lungs has provided the groundwork for mechanistic translational studies that confirm and extend findings from model systems and spontaneous pulmonary hypertension in animals. Endothelial cell hyperproliferation, survival, and alterations of biochemical-metabolic pathways are the unifying endothelial pathobiology of the disease. The hyperproliferative and apoptosis-resistant phenotype of PAH endothelial cells is dependent upon the activation of signal transducer and activator of transcription (STAT) 3, a fundamental regulator of cell survival and angiogenesis. Animal models of PAH, patients with PAH, and human PAH endothelial cells produce low nitric oxide (NO). In association with the low level of NO, endothelial cells have reduced mitochondrial numbers and cellular respiration, which is associated with more than a threefold increase in glycolysis for energy production. The shift to glycolysis is related to low levels of NO and likely to the pathologic expression of the prosurvival and proangiogenic signal transducer, hypoxia-inducible factor (HIF)-1, and the reduced mitochondrial antioxidant manganese superoxide dismutase (MnSOD). In this article, we review the phenotypic changes of the endothelium in PAH and the biochemical mechanisms accounting for the proliferative, glycolytic, and strongly proangiogenic phenotype of these dysfunctional cells, which consequently foster the panvascular progressive pulmonary remodeling in PAH.

Development of vascular smooth muscle contractility by endothelium-derived transforming growth factor β proteins

It is well established that the release of vasodilators and vasoconstrictors from vascular endothelium regulates vascular smooth muscle contraction. In this report, we investigate the role of the endothelium in the development and maintenance of constitutive vascular contractility. For that purpose, contractile activity of cultured bovine aortic smooth muscle cells (BASMCs) embedded in collagen gels was monitored by changes in gel diameter. After culturing for 5 days, ATP- and high KCl solution-induced contractions were significantly enhanced in the gels that were overlaid with bovine aortic endothelial cells (BAECs) or were cultured with conditioned medium of cultured BAECs. ATP-induced Ca(2+) transients, recorded in BASMCs cultured with conditioned medium of BAECs, were markedly augmented, but high KCl-induced Ca(2+) transients were not affected. BASMCs in control gels were spindle shaped, and those in endothelium-treated gels were more elongated and interconnected. The endothelial conditioned medium also strongly affected the intracellular distribution of actin fibers. Conditioned medium of BAECs contained TGFβ1 and TGFβ2. The TGFβ receptor antagonist SB431542 as well as simultaneous treatment with TGFβ1 and TGFβ2 neutralizing antibodies completely reversed the above effects of endothelial conditioned medium on BASMCs. BAECs medium induced phosphorylation of Smad2 and increased ATP-induced phosphorylation of myosin light chain in BASMCs. The present results indicate that the release of TGFβ1 and TGFβ2 from vascular endothelium affects the contractility of vascular smooth muscle cells by altering their morphology and agonist-induced Ca(2+) mobilization.

Central arterial aging and the epidemic of systolic hypertension and atherosclerosis

The structure and function of central arteries change throughout the lifetime of humans and animals. Since atherosclerosis and hypertension are prevalent in epidemic proportion among older persons, it is reasonable to hypothesize that specific mechanisms that underlie the arterial substrate that has been altered by an "aging process" are intimately linked to arterial diseases. Indeed, recent studies reveal a profile of arterial cell and matrix properties that emerges with advancing age within the grossly normal appearing aortic wall of both animals and humans. This profile is proinflammatory, and is manifested by intimal infiltration of fetal cells, increased production of angiotensin II (Ang II)-signaling pathway molecules, eg, matrix metalloproteases (MMPs), and monocyte chemoattractant protein (MCP-1), transforming growth factor B1 (TGF-beta1), enhanced activation of MMPs, TGF-beta, and NADPH oxidase, and reduced nitric oxide (NO) bioavailability. This profile is similar to that induced at younger ages in experimental animal models of hypertension or atherosclerosis. In humans, this proinflammatory state, which occurs in the absence of lipid deposition, appears to be attributable to aging, per se. Other well known human risk factors, eg, altered lipid metabolism, smoking, and lack of exercise, interact with this arterial substrate that is altered by aging and render the aging human artery fertile soil for facilitation of the initiation and progression of arterial diseases. Therapies to reduce or retard this age-associated proinflammatory state within the grossly appearing arterial wall central arteries, in addition to slowing arterial aging, per se, may have a substantial impact on the quintessential age-associated arterial diseases of our society.

Overexpression of TGF-ß1 in macrophages reduces and stabilizes atherosclerotic plaques in ApoE-deficient mice

Although macrophages represent the hallmark of both human and murine atherosclerotic lesions and have been shown to express TGF-ß1 (transforming growth factor β1) and its receptors, it has so far not been experimentally addressed whether the pleiotropic cytokine TGF-ß1 may influence atherogenesis by a macrophage specific mechanism. We developed transgenic mice with macrophage specific TGF-ß1 overexpression, crossed the transgenics to the atherosclerotic ApoE (apolipoprotein E) knock-out strain and quantitatively analyzed both atherosclerotic lesion development and composition of the resulting double mutants. Compared with control ApoE^−/− mice, animals with macrophage specific TGF-ß1 overexpression developed significantly less atherosclerosis after 24 weeks on the WTD (Western type diet) as indicated by aortic plaque area en face (p<0.05). Reduced atherosclerotic lesion development was associated with significantly less macrophages (p<0.05 after both 8 and 24 weeks on the WTD), significantly more smooth muscle cells (SMCs; p<0.01 after 24 weeks on the WTD), significantly more collagen (p<0.01 and p<0.05 after 16 and 24 weeks on the WTD, respectively) without significant differences of inner aortic arch intima thickness or the number of total macrophages in the mice pointing to a plaque stabilizing effect of macrophage-specific TGF-ß1 overexpression. Our data shows that macrophage specific TGF-ß1 overexpression reduces and stabilizes atherosclerotic plaques in ApoE-deficient mice.

Interference of IP-10 expression inhibits vascular smooth muscle cell proliferation and intimal hyperplasia in carotid artery: a new insight in the prevention of restenosis

After vascular angioplasty, vascular smooth muscle cell (VSMC) proliferation causes atherosclerosis and intimal hyperplasia leading to restenosis. Interferon-γ-inducible protein (IP)-10 plays a role in atherogenesis, but the mechanism remains unclear. We evaluated the role of IP-10 in intimal hyperplasia and restenosis. IP-10 expression was determined in arterial specimens from 20 arteriosclerotic obliteration patients and 6 healthy individuals. VSMCs were stimulated in vitro with IFN-γ and transfected with IP-10 siRNA. Silencing was verified with RT-PCR/Western blot; cell proliferation rate was detected by methyl-thiazol-tetrazolium. The carotid artery model of atherosclerosis injury was established with IP-10 siRNA. IP-10 expression was detected at 1 and 4 weeks using RT-PCR and immunohistochemistry. Artery morphology was assessed with hematoxylin-and-eosin staining, and intimal hyperplasia was evaluated by electron microscopy. IP-10 was overexpressed in arteriosclerotic obliteration group compared with control group (P < 0.05). IP-10 expression in transfected group was significantly lower than in untransfected group. The intima-to-media ratio of transfected group at 4 weeks was lower than that of untransfected group (P < 0.01). The transfected group exhibited more regular intimal structure and less hyperplasia under electron microscopy. We, therefore, concluded that IP-10 played an important role in intimal hyperplasia as siRNA-mediated IP-10 silencing inhibited aberrant VSMCs hyperplasia and reduced restenosis.

TGFβ signaling and cardiovascular diseases

Transforming growth factor β (TGFβ) family members are involved in a wide range of diverse functions and play key roles in embryogenesis, development and tissue homeostasis. Perturbation of TGFβ signaling may lead to vascular and other diseases. In vitro studies have provided evidence that TGFβ family members have a wide range of diverse effects on vascular cells, which are highly dependent on cellular context. Consistent with these observations genetic studies in mice and humans showed that TGFβ family members have ambiguous effects on the function of the cardiovascular system. In this review we discuss the recent advances on TGFβ signaling in (cardio)vascular diseases, and describe the value of TGFβ signaling as both a disease marker and therapeutic target for (cardio)vascular diseases.

Egr-1 deficiency in bone marrow-derived cells reduces atherosclerotic lesion formation in a hyperlipidaemic mouse model

AIMS

Early growth response gene-1 (Egr-1) regulates the expression of genes important to cardiovascular disease. Within atherosclerotic lesions, Egr-1 is expressed in smooth muscle cells, endothelial cells, and macrophages. Since macrophages play a pivotal role in atherosclerotic lesion initiation and progression, this study investigated the effects of Egr-1 deficiency within bone marrow-derived cells on the development of atherosclerosis in a hyperlipidaemic mouse model.

METHODS AND RESULTS

Bone marrow from Egr-1-deficient mice and wild-type controls was transplanted into lethally irradiated LDL receptor null mice. After 26 weeks on a high fat diet, atherosclerotic lesion size within the aortic sinus of recipients was evaluated. Mice receiving Egr-1-deficient bone marrow had significantly decreased lesion size compared with controls. Lesions of these mice contained fewer macrophages and had reduced expression of vascular cell adhesion molecule-1 (VCAM-1), tissue factor, as well as transforming growth factor receptor type II, which are target genes of Egr-1. These results were validated by in vitro analysis of Egr-1-deficient peritoneal macrophages which, after lipopolysaccharide stimulation, had decreased VCAM-1 and tissue factor mRNA expression compared with wild-type controls.

CONCLUSION

This study demonstrates that bone marrow-derived Egr-1 promotes macrophage accumulation, atherosclerotic lesion development, and lesion complexity.

Blockade of TGF-β by catheter-based local intravascular gene delivery does not alter the in-stent neointimal response, but enhances inflammation in pig coronary arteries

BACKGROUND

Extracellular matrix (ECM) accumulation significantly contributes to in-stent restenosis. In this regard, transforming growth factor (TGF)-β, a positive regulator of ECM deposition, may be implicated in in-stent restenosis. The goal of this study was to assess the effect of blockade of TGF-β on stent-induced restenosis in porcine coronary arteries.

METHODS

An adenovirus expressing the ectodomain of the TGF-β type II receptor (AdTβ-ExR) was applied onto a coronary arterial segment of a pig (n=10) using an Infiltrator, followed by stent deployment. Controls consisted of adenoviruses expressing β-galactosidase (AdLacZ) or phosphate-buffered saline (PBS) applied onto the other segment (n=10) of the same pig.

RESULTS

Computer-based pathological morphometric analysis of stented coronary arteries, performed 4 weeks after stenting, demonstrated no significant difference in morphometric parameters such as in-stent neointimal area and % area stenosis between the AdTβ-ExR group and control (n=7 for each). However the AdTβ-ExR group had increased neointimal cell density, infiltration of inflammatory cells mostly consisting of CD3+ T cell, accumulation of hyaluronan, cell proliferation rate, and adventitial matrix metalloproteinase-1 (MMP-1) expression compared with control. The expression of connective tissue growth factor mRNA, measured by reverse transcription PCR, in cultured rat arterial smooth muscle cells was inhibited by AdTβ-ExR at moi 60.

CONCLUSIONS

Blockade of TGF-β by catheter-based local intravascular gene delivery does not reduce stent-induced neointima formation 4 weeks after stenting in spite of modest inhibition of ECM accumulation, but it induces vascular inflammation and associated pathological changes that may potentially aggravate lesion progression.

The development and endocrine functions of adipose tissue

White adipose tissue is a mesenchymal tissue that begins developing in the fetus. Classically known for storing the body's fuel reserves, adipose tissue is now recognized as an endocrine organ. As such, the secretions from adipose tissue are known to affect several systems such as the vascular and immune systems and play major roles in metabolism. Numerous studies have shown nutrient or hormonal manipulations can greatly influence adipose tissue development. In addition, the associations between various disease states, such as insulin resistance and cardiovascular disease, and disregulation of adipose tissue seen in epidemiological and intervention studies are great. Evaluation of known adipokines suggests these factors secreted from adipose tissue play roles in several pathologies. As the identification of more adipokines and determination of their role in biological systems, and the interactions between adipocytes and other cells types continues, there is little doubt that we will gain a greater appreciation for a tissue once thought to simply store excess energy.

Transforming growth factor-beta1 elicits Nrf2-mediated antioxidant responses in aortic smooth muscle cells

The anti-inflammatory properties of transforming growth factor-beta(1) (TGF-beta(1)) account for its protection against atherosclerotic plaque rupture. This study investigates whether activation of the Nrf2 (nuclear factor erythroid 2 [NF-E2]-related factor 2) transcription pathway is involved in TGF-beta(1) mediated induction of the antioxidant enzyme heme oxygenase-1 (HO-1) in smooth muscle cells (SMC). Human aortic smooth muscle cells (HAoSMC) or wild-type and Nrf2-deficient mouse (MAoSMC) aortic SMC were treated with TGF-beta(1) (2.5-10 ng/ml, 0-24 hrs). We report the first evidence that TGF-beta(1) induces Nrf2 mediated HO-1 expression and antioxidant response element activity, which was paralleled by enhanced superoxide production and expression of the NAD(P)H oxidase subunit p22(phox). TGF-beta(1) failed to induce HO-1 expression in MAoSMC derived from Nrf2-deficient mice, and HO-1 induction by TGF-beta(1) in HAoSMC was attenuated by inhibition of extracellular signal regulated kinase or c-jun-N-terminal kinase but not p38 mitogen activated protein kinase. Inhibition of NAD(P)H oxidase or scavenging of superoxide diminished HO-1 induction in response to TGF-beta(1). The oxidative stress agents glucose oxidase (GOx) and diethylmaleate enhanced TGF-beta(1) generation and HO-1 expression in HAoSMC, while antagonism of TGF-beta(1) signalling by adenoviral Smad7 overexpression attenuated their induction of HO-1. Pre-treatment of HAoSMC with TGF-beta(1) reduced nuclear translocation of the pro-apoptotic mediator p53 elicited by GOx. Our findings demonstrate that Nrf2 is a new target of TGF-beta(1) signalling in the vasculature which may contribute to the atheroprotective properties attributed to this growth factor.

Enhanced susceptibility of cyclin kinase inhibitor p21 knockout mice to high fat diet induced atherosclerosis

Cyclin kinase inhibitor p21 is one of the most potent inhibitors of aortic smooth muscle cell proliferation, a key mediator of atherosclerosis. This study tests if p2l deficiency will result in severe atherosclerosis in a mouse model. p21-/- and strain matched wild type mice were fed with high fat diet for 21 weeks. Analysis for biochemical parameters (cholesterol, triglycerides) in serum and mRNA expression of CD36, HO-1, TGF-beta, IFN-gamma, TNF-alpha, PPAR-gamma and NADPH oxidase components (p22phox, NOX-1 and Rac-1) was performed in aortic tissues by Real Time PCR. p21-/- mice gained significantly (p < 0.01) more weight than wild type mice, triglycerides (p < 0.05) and cholesterol levels (p < 0.01) were more pronounced in the sera of p21-/- compared to wild type mice fed with high fat diet. High fat diet resulted in significantly decreased TGF-beta (p < 0.02), HO-l (p < 0.02) and increased CD36 (p < 0.03) mRNA expression in aortic tissues of p21-/- mice compared to animal fed with regular diet. IFN-gamma mRNA expression (235 +/- 11 folds) increased significantly in high fat diet fed p21-/- mice and a multifold modulation of PPAR-gamma(136 +/- 7), p22phox, NOX-1 and Rac-1 (15-35-folds) mRNA in aortic tissues from p21-/- mice compared to the wild type mice. Severity of atherosclerotic lesions was significantly higher in p21-/- compared to wild type mice. The results demonstrate that the deficiency of p21 leads to altered expression of pro-atherogenic genes, and severe atherosclerosis in mice fed with high fat diet. This opens the possibility of p21 protein as a therapeutic tool to control progression of atherosclerosis.

Gene profiling of keloid fibroblasts shows altered expression in multiple fibrosis-associated pathways

Keloids are benign tumors of the dermis that form during a protracted wound healing process. Susceptibility to keloid formation occurs predominantly in people of African and Asian descent. The key alteration(s) responsible for keloid formation has not been identified and there is no satisfactory treatment for this disorder. The altered regulatory mechanism is limited to dermal wound healing, although several diseases characterized by an exaggerated response to injury are prevalent in individuals of African ancestry. We have observed a complex pattern of phenotypic differences in keloid fibroblasts grown in standard culture medium or induced by hydrocortisone (HC). In this study Affymetrix-based microarray was performed on RNA obtained from fibroblasts cultured from normal scars and keloids grown in the absence and presence of HC. We observed differential regulation of approximately 500 genes of the 38,000 represented on the Affymetrix chip. Of particular interest was increased expression of several IGF-binding and IGF-binding-related proteins and decreased expression of a subset of Wnt pathway inhibitors and multiple IL-1-inducible genes. Increased expression of connective tissue growth factor and insulin-like growth factor binding protein-3 was observed in keloid fibroblasts only in the presence of HC. These findings support a role for multiple fibrosis-related pathways in the pathogenesis of keloids.

Circulating angiogenic precursors in idiopathic pulmonary arterial hypertension

Vascular remodeling in idiopathic pulmonary arterial hypertension (IPAH) involves hyperproliferative and apoptosis-resistant pulmonary artery endothelial cells. In this study, we evaluated the relative contribution of bone marrow-derived proangiogenic precursors and tissue-resident endothelial progenitors to vascular remodeling in IPAH. Levels of circulating CD34+ CD133+ bone marrow-derived proangiogenic precursors were higher in peripheral blood from IPAH patients than in healthy controls and correlated with pulmonary artery pressure, whereas levels of resident endothelial progenitors in IPAH pulmonary arteries were comparable to those of healthy controls. Colony-forming units of endothelial-like cells (CFU-ECs) derived from CD34+ CD133+ bone marrow precursors of IPAH patients secreted high levels of matrix metalloproteinase-2, had greater affinity for angiogenic tubes, and spontaneously formed disorganized cell clusters that increased in size in the presence of transforming growth factor-beta or bone morphogenetic protein-2. Subcutaneous injection of NOD SCID mice with IPAH CFU-ECs within Matrigel plugs, but not with control CFU-ECs, produced cell clusters in the Matrigel and proliferative lesions in surrounding murine tissues. Thus, mobilization of high levels of proliferative bone marrow-derived proangiogenic precursors is a characteristic of IPAH and may participate in the pulmonary vascular remodeling process.

Wine polyphenols and promotion of cardiac health

Wine polyphenols are considered to have beneficial effects on CHD and atherosclerosis. The consumption of red wine is high in Italy and France, approximately four times greater than that in the UK. This disparity in red wine consumption is thought to be the reason for the ‘French paradox’, where France was shown to have a coronary mortality rate close to that of China or Japan despite saturated fat intakes and cholesterol levels similar to the UK and USA. In the present review, we discuss the effects of wine and some of its polyphenol constituents on early pathological indicators of CHD such as plasma lipids, the endothelium and vasculature, platelets and serum antioxidant activity. The review also examines whether the polyphenols or the alcohol in wine is responsible for the effects on markers of heart disease. The present review concludes that red wine polyphenols have little effect on plasma lipid concentrations but wine consumption appears to reduce the susceptibility of LDL to oxidation and increase serum antioxidant capacity. However, these effects do depend on the amount of wine and period of supplementation. Authors who have examined specific polyphenols suggest that some phenolics appear to have endothelium-dependent vaso-relaxing abilities and some a positive effect on NO concentrations. Red wine phenolics also have an inhibitory effect on platelet aggregation, and individual phenolics also have a similar effectin vitro, although it should be noted that there are often discrepancies as large as ten-fold between the concentrations of polyphenolics testedin vitroand their measured levelsin vivo. Evidence suggests that alcohol has a positive synergistic effect with wine polyphenols on some atherosclerotic risk factors. Thus evidence that wine drinking is beneficial for cardiac health continues to accumulate but more research is required to understand fully and exactly the functions of red wine polyphenols.

Long-term treatment with TGFbeta1 impairs mechanotransduction in bovine aortic endothelial cells

BACKGROUND AND PURPOSE

Vascular endothelial cells play a role in the physiological response to mechanical stress. Transforming growth factor beta1 (TGFbeta1) induces morphological changes in endothelial cells, and this may alter their mechanosensitive responses. The aim of this study was to examine the effects of TGFbeta1 on hypotonic stress (HTS)-induced responses in bovine aortic endothelial cells (BAECs).

EXPERIMENTAL APPROACH

Cultured BAECs were treated with 3 ng ml(-1) TGFbeta1 for 24 h (24h-TGFbeta1) or 7 days (7d-TGFbeta1). Cytosolic actin fibres were stained with rhodamine-phalloidin. Intracellular Ca2+ concentration was measured using fura2. Tyrosine phosphorylation and RhoA expression were assessed by Western blotting. Expression of RhoA mRNA was assessed by real-time PCR.

KEY RESULTS

BAECs developed pseudopod-like processes within 24 h and showed a fibroblast-like appearance after 7 days. HTS induced Ca2+ transients via endogenous ATP release in both control and 24h-TGFbeta1 BAECs but not in 7d-TGFbeta1 BAECs. We have previously shown that HTS-induced ATP release is mediated by sequential activation of RhoA and tyrosine kinases. The basal amount of membrane-bound RhoA was significantly lower in 7d-TGFbeta1 than in 24h-TGFbeta1 or control BAECs. HTS increased the membrane-bound RhoA to the same fractional level in 24h-TGFbeta1 and control BAECs, but its net maximal amount was significantly lower in 7d-TGFbeta1. HTS-induced downstream signals of RhoA activation, i.e. the tyrosine phosphorylation of FAK and paxillin, were markedly suppressed in 7d-TGFbeta1 BAECs.

CONCLUSIONS AND IMPLICATIONS

These results indicate that long-term treatment with TGFbeta1 does not impair mechanoreception in BAECs but impairs mechanotransduction by affecting RhoA membrane translocation.

A comparative study of neovascularisation in atherosclerotic plaques using CD31, CD105 and TGF beta 1

OBJECTIVES

This study aims to identify plaque neovascularisation using antibodies to CD31, CD105 and TGFbeta1, and to compare their patterns of expression.

METHODS

Tissue expression of CD31, CD105 and TGFbeta1 was examined immunohistologically in atherosclerotic plaques from 53 patients who had undergone carotid endarterectomy and in 10 controls.

RESULTS

CD31 was observed in a proportion of the microvessels within atheroma. The expression of CD105 was barely visible in normal arteries, but was markedly enhanced in atherosclerotic plaques. The vast majority of the microvessels in atheroma were positive for CD105 with pronounced expression around the periphery of the lipid core. In consecutive sections, microvessels showing negative staining for CD31 were positive for CD105. Although TGFbeta1 was seen in the thickened intima, it was more strongly expressed in well-formed fibrous plaques. Consecutive sections showed that some microvessels were stained by both CD105 and TGFbeta1, but in certain areas microvessels were exclusively CD105 positive.

CONCLUSIONS

These observations highlight the distinctive expression patterns of CD31, CD105 and TGFbeta1, suggesting their specific roles in the development of atherosclerotic plaques. CD105 is almost universally expressed in microvessels within the atheroma and is therefore a better vascular marker than CD31 and TGFbeta1for assessing neovascularisation in atherosclerotic plaques.

Poly(ADP-ribose) polymerase inhibition combined with irradiation: a dual treatment concept to prevent neointimal hyperplasia after endarterectomy

PURPOSE

In a rat model of endarterectomy we investigated the potential role of the peroxynitrite-poly(ADP-ribose) polymerase (PARP) pathway in neointima formation and the effects of irradiation, pharmacologic inhibition of PARP, or combined pharmacologic inhibition of PARP and irradiation on vascular remodeling.

METHODS AND MATERIALS

Carotid endarterectomy was performed by incision of the left carotid artery with removal of intima in Sprague-Dawley rats. Six groups were studied: sham-operated rats (n = 10), control endarterectomized rats (n = 10), or endarterectomized rats irradiated with 15 Gy (n = 10), or treated with PARP inhibitor, INO-1001 (5 mg/kg/day) (n = 10), or with combined treatment with INO-1001 and irradiation with 5 Gy (n = 10) or with 15 Gy (n = 10). After 21 days, neointima formation and vascular remodeling were assessed.

RESULTS

Neointima formation after endarterectomy was inhibited by postoperative irradiation with 15 Gy and was attenuated by PARP inhibition. However, in parallel to inhibition of neointimal hyperplasia, activation of the peroxynitrite-PARP pathway in the outer vessel wall layers was triggered by postoperative irradiation. Combined pharmacologic PARP inhibition and irradiation with 15 Gy significantly reduced both neointimal hyperplasia and activation of the peroxynitrite-PARP pathway in the outer vessel wall layers. Combination of PARP inhibition and irradiation with 5 Gy was less effective than both PARP inhibition or irradiation with 15 Gy alone.

CONCLUSIONS

We conclude, that combined PARP inhibition and irradiation with 15 Gy may be a new dual strategy for prevention of restenosis after surgical vessel reconstruction: combining the strong antiproliferative effect of irradiation and ameliorating irradiation-induced side effects caused by excessive PARP activation.

Sustained contraction and loss of NO production in TGFbeta1-treated endothelial cells

BACKGROUND AND PURPOSE

Transforming growth factor beta1 (TGFbeta1) is generated in atherosclerotic and injured vessel walls. We examined whether the endothelial-to-mesenchymal transdifferentiation induced by TGFbeta1 affects endothelial functions.

EXPERIMENTAL APPROACH

Bovine aortic endothelial cells (BAECs) were treated with 3 ng ml(-1) TGFbeta1 for 7 days. Contraction of TGFbeta1-treated BAECs was assessed by collagen gel contraction assay. Protein expression and phosphorylation were assessed by Western blotting. Intracellular Ca2+ concentration and NO production were measured using fura2 and DAF-2, respectively.

KEY RESULTS

TGFbeta1-treated BAECs showed dense actin fibers and expressed smooth muscle marker proteins; they also changed into smooth muscle-like, spindle-shaped cells in collagen gel cultures. ATP (10 microM) induced a gradual contraction of collagen gels containing TGFbeta1-treated BAECs but not of gels containing control BAECs. ATP-induced contraction of TGFbeta1-treated BAECs was not reversed by the removal of ATP but was partially suppressed by a high concentration of sodium nitroprusside (1 microM). TGFbeta1-treated BAECs showed sustained phosphorylation of myosin light chain in response to ATP and low levels of basal MYPT1 expression. ATP-induced Ca2+ transients as well as eNOS protein expression were not affected by TGFbeta1 in BAECs. However, ATP-induced NO production was significantly reduced in TGFbeta1-treated BAECs. Anti-TGFbeta1 antibody abolished all of these TGFbeta1-induced changes in BAECs.

CONCLUSIONS AND IMPLICATIONS

Mesenchymal transdifferentiation induced by TGFbeta1 leads to sustained contraction and reduced NO production in endothelial cells. Such effects, therefore, would not be beneficial for vascular integrity.

Effects of 2,3,7,8-tetrachloro-dibenzo-p-dioxin on the extracellular matrix of the thymus in juvenile marmosets (Callithrix jacchus)

2,3,7,8-Tetrachloro-dibenzo-p-dioxin (TCDD) is an ubiquitously distributed xenobiotic. It has been postulated that the effects of TCDD on T-lymphocytes are mediated by modulation of the thymic microenvironment. There is growing evidence of a modified interplay between thymocytes and thymic epithelium related to changes in extracellular matrix (ECM) proteins. Eighteen male marmosets (Callithrix jacchus) were treated with single subcutaneous TCDD doses (1, 10, 100 ng/kg body weight) or vehicle and sacrificed 2 or 4 weeks thereafter. Thymus samples were stained with fluorescein isothiocyanate-conjugated antibodies for ECM proteins and examined immunohistochemically by semi-quantitative image analysis. Thymus samples of animals treated with 1 and 10 ng/kg were additionally analysed by Western blotting for ECM proteins, transforming growth factor-beta(1) (TGF-beta(1)) and integrin chain content (CD49a, CD49e, CD49f and CD29). Monkeys showed no overt signs of toxicity after TCDD treatment. Immunohistochemistry revealed an increase of ECM proteins at 100 ng/kg after 2 and 4 weeks. Western blotting confirmed immunohistochemistry showing a dose-dependent increase of several ECM proteins in animals treated with the lower TCDD doses of 1 and 10 ng/kg. Additionally, dose-dependent increases were observed in integrin chain and TGF-beta(1) contents. We demonstrated changes of thymic ECM in marmosets following low single TCDD doses. Combined with altered integrin expression and enhanced TGF-beta(1) stimulation our findings suggest a modified interplay between thymic epithelium and thymocytes. The extracellular matrix may play a more central role in mediating adverse effects of TCDD in organs than yet acknowledged.

TGF-beta1 generates a specific multicomponent extracellular matrix in human coronary SMC

BACKGROUND

Transforming growth factor (TGF-beta(1)) is postulated to play an important role in maintaining the structure and function of arterial tissue and protection against development of arteriosclerosis. The TGF-beta(1)-induced production of a stable extra-cellular matrix-rich plaque phenotype is suggested to be part of the protection against a switch to an unstable rupture-prone arteriosclerotic plaque.

MATERIALS AND METHODS

This study addresses the question of whether the expression profile and the type of extra-cellular matrix (ECM) generated by TGF-beta(1) stimulation have the structural feature of a fibril-rich stable matrix. Seventeen genes codings for ECM components of human coronary smooth muscle cells (SMCs) after a 24-h stimulation by TGF-beta(1) have been analyzed.

RESULTS

Real-time RT-PCR was used to quantify the mRNA of genes under investigation. It was found that after TGF-beta(1) stimulation (a) the up-regulation of COL1A1-specific mRNA was associated with increased [(3)H]proline incorporation into the alpha-1 and -2 chains of collagen type I, (b) the up-regulation of biglycan- and syndecan-1-specific mRNA corresponded to an increased [(35)S]sulphate and [4,5-(3)H]leucine incorporation into the biglycan molecule and to an increase of syndecan-1 protein, (c) the up-regulated FGF-2 gene accounted predominantly for the ECM-bound subfraction of FGF-2-protein and (d) fibronectin and thrombospondin exhibited a significantly higher mRNA level. In contrast collagen XIV, a minor collagen type, and the proteoglycan decorin were down-regulated. The down-regulated decorin changed its structure by elongation and reduced GlcA to IdoA epimerization of the dermatan sulphate side-chain as judged by [(35)S]sulphate metabolic labelling experiments. No significant changes in response to TGF-beta(1) were observed for the collagen types III, VI and XVI, for versican, perlecan and the syndecans-2 and -4.

CONCLUSIONS

It was concluded from the data that the TGF-beta(1)-induced formation of a highly specific multicomponent extra-cellular matrix on coronary arterial SMCs could provide in vivo mechanical strength to the neointima in arteriosclerotic lesions and to the fibrous cap overlying the lipid core.

Activation of the peroxynitrite-poly(adenosine diphosphate-ribose) polymerase pathway during neointima proliferation: a new target to prevent restenosis after endarterectomy

OBJECTIVE

In a rat model of endarterectomy, we investigated the potential role of the peroxynitrite-poly(adenosine diphosphate[ADP]-ribose) polymerase (PARP) pathway in neointima formation and the effect of pharmacologic inhibition of PARP on vascular remodeling.

METHODS

Carotid endarterectomy was performed in male Sprague-Dawley rats by incision of the left carotid artery with removal of intima. Three groups were studied: sham-operated rats (n = 10), control rats with endarterectomy (n = 10) or rats with endarterectomy treated with the PARP inhibitor, INO-1001 (5 mg/kg daily) postoperatively (n =10). After 21 days, neointima formation and vascular remodeling were assessed.

RESULTS

Immunohistochemistry analysis demonstrated activation of the peroxynitrite-PARP pathway with significant staining for nitrotyrosine, poly(ADP-ribose), and nuclear translocation of apoptosis-inducing factor (AIF) in the neointima of the control group. Treatment with INO-1001 significantly reduced the neointima area (0.024 mm2 +/- 0.019 mm2 vs 0.089 mm2 +/- 0.033 mm2 in the control group), the neointima/media thickness ratio (0.81 +/- 0.05 vs 2.76 +/- 1.57 in the control group), and the inflammation score (0.1 +/- 0.07 vs 0.3 +/- 0.12 in the control group) after endarterectomy.

CONCLUSIONS

Pharmacologic inhibition of PARP with INO-1001 may be a new concept to prevent neointimal hyperplasia after endarterectomy.

Suppression of atherogenesis by delivery of TGFbeta1ACT using adeno-associated virus type 2 in LDLR knockout mice

TGFbeta(1) deficiency has been attributed to the development of atherosclerosis. There is, however, little direct evidence for this concept. To examine this hypothesis, low-density lipoprotein receptor knockout (LDLR(-/-)) mice were injected via tail vein with recombinant adeno-associated virus type 2 (rAAV) carrying a bioactive TGFbeta(1) mutant (AAV/TGFbeta1ACT, n=10) or granulocyte-macrophage-colony stimulating factor (AAV/GM-CSF, n=10, a negative control) or saline (n=9, control), and then put on a high cholesterol diet. At 18 weeks, blood lipids were found to be similarly elevated in all LDLR(-/-) mice. TGFbeta1ACT and GM-CSF (DNA, mRNA, and protein) were highly expressed in the tissues of mice given TGFbeta1ACT or AAV/GM-CSF, respectively, showing sustained transfection following gene delivery by the systemic route. Saline-treated and AAV/GM-CSF-treated LDLR(-/-) mice showed extensive areas of atherosclerotic lesion formation. There was evidence of intense oxidative stress (nitrotyrosine staining), inflammation (CD68 staining), and expression of adhesion molecules and the ox-LDL receptor LOX-1 (gene array analysis) in the atherosclerotic tissues. Importantly, atherosclerotic lesion formation was markedly inhibited in the LDLR(-/-) mice given AAV/TGFbeta1ACT. Expression of adhesion molecules and LOX-1, oxidative stress, and inflammatory response all were inhibited in the mice given AAV/TGFbeta1ACT (P<0.05 vs. saline-treated or GM-CSF-treated LDLR(-/-) mice). These data for the first time demonstrate that systemic delivery of TGFbeta1ACT gene via AAV can inhibit formation of atherosclerotic lesions, possibly via anti-inflammatory and anti-oxidant mechanisms. These findings suggest a novel view of TGFbeta(1) in atherogenesis and a potential new gene therapy for treatment of atherosclerosis.

Reduction of myointimal hyperplasia after arterial anastomosis by local injection of transforming growth factor beta3

BACKGROUND

The transforming growth factor (TGF)-beta family of cytokines exerts pleiotropic actions on vascular smooth muscle cell phenotype, proliferation, and extracellular matrix synthesis. This in vivo study assessed the use of TGF-beta3 in attenuating the development of postanastomotic smooth muscle cell proliferation.

METHODS

Under general anesthesia, 10 adult goats underwent transection and reanastomosis of both common carotid arteries. After reanastomosis, one artery was infiltrated with 50 ng of TGF-beta3 in 100 microL of pH buffer around the anastomosis, and the other side was infiltrated with buffer only. After surgery, each animal received 150 mg of aspirin daily. The arteries were explanted after 3 months for histologic examination.

RESULTS

Vessel wall thickness surrounding the anastomosis was reduced by 30% after TGF-beta3 treatment compared with placebo (P = .003), with a 20% (P = .002) reduction in cellular content. Although total collagen content was not significantly different between TGF-beta3 and placebo, collagen type VIII content was reduced around the TGF-beta3 anastomoses (P = .011). A reduction in the total elastin content (P = .003) and number of elastic fiber lamellae (P = .042) was found surrounding TGF-beta3-treated anastomoses, but not placebo-treated anastomosis. A 29% increase in vasa vasorum (P = .044) was present around TGF-beta3-treated anastomoses. No differences in inflammatory cell infiltration were seen between sides.

CONCLUSIONS

Direct subadventitial infiltration of TGF-beta3 immediately after creation of an arterial anastomosis attenuates cell proliferation, with a reduction in elastin and collagen type VIII content and vessel wall thickness.

Eplerenone suppresses neointimal formation after coronary stent implantation in swine

BACKGROUND

Enhanced extracellular matrix accumulation rather than cell proliferation contributes to later stages of in-stent restenosis. Aldosterone itself has been shown to increase cardiovascular fibrosis, therefore, we studied the suppressive effects of eplerenone, a new aldosterone receptor antagonist, on neointimal hyperplasia after coronary stent implantation in swine.

METHODS

Palmatz-Shatz stents were implanted in the left anterior descending artery of 36 pigs. One hundred milligrams of Eplerenone was orally administered from 1 week before, to 4 weeks after stent implantation in Group E (n=18), and vehicle was given to Group C (n=18). Pigs were sacrificed 1 or 4 weeks after stent implantation. The number of infiltrating macrophages was calculated at 1 week. Morphometrical analysis was performed to measure the area of each layer, and %area of fibrosis and mRNA for collagen I, III and TGF-beta was analyzed by RT-PCR at 4 weeks.

RESULTS

The number of infiltrating macrophages was less in Group E than in Group C (p<0.01). The overall size of coronary arteries at 4 weeks was similar in both groups. However, the luminal area was larger in Group E than in Group C (p<0.05), and the intimal area was smaller in Group E than in Group C (p<0.05). The %area of fibrosis was significantly less in Group E than in Group C at 4 weeks (p<0.01). In Group E, the expression of mRNA for collagen I, III and TGF-beta was significantly reduced.

CONCLUSION

Orally administered eplerenone attenuated collagen accumulation within the neointima, thereby inhibiting neointimal hyperplasia after stent implantation.

Interleukin-8 differentially regulates migration of tumor-associated and normal human brain endothelial cells

Interleukin-8 (IL-8) is a chemokine involved in angiogenesis, a process vital to tumor growth. Previously, we showed that endothelial cells derived from human tumor tissue have different functional and phenotypic properties compared with normal endothelial cells. This study analyzes the role of IL-8 in regulating angiogenesis of tumor-associated brain endothelial cells (TuBEC). Results show that TuBECs have a higher baseline migration rate compared with normal brain endothelial cells (BEC). TuBECs are unaffected when stimulated with IL-8 whereas BECs are activated. This lack of response of TuBECs to IL-8 is due to the constitutive production of IL-8. Endogenously produced IL-8 activates TuBECs in an autocrine manner as shown by IL-8 receptor inhibition. Blocking either CXCR1 or CXCR2 partially reduces TuBEC migration, whereas blocking both receptors further reduces migration. Treatment with antibody against vascular endothelial growth factor (VEGF) shows that production of IL-8 by TuBECs is dependent on VEGF. Transforming growth factor-beta1 (TGF-beta1), shown to down-regulate IL-8 production in BECs, does not inhibit IL-8 production in TuBECs. In summary, these studies show that TuBECs constitutively secrete IL-8 and autocrine activation by IL-8 is the result of VEGF stimulation. Furthermore, TuBECs do not respond to the feedback inhibition normally induced by TGF-beta1. These data emphasize the functional uniqueness of TuBECs. Understanding the functions and regulatory processes of tumor-associated endothelial cells is critical for developing appropriate antiangiogenic therapies.

Transforming growth factor beta 1 induces neointima formation through plasminogen activator inhibitor-1-dependent pathways

OBJECTIVE

The mechanisms through which transforming growth factor (TGF)-beta1 promotes intimal growth, and the pathways through which TGF-beta1 expression is regulated in the artery wall, are incompletely understood. We used a mouse model to investigate mechanisms of TGF-beta1-induced intimal growth.

METHODS AND RESULTS

Adenovirus-mediated overexpression of TGF-beta1 in uninjured carotid arteries of wild-type mice induced formation of a cellular and matrix-rich intima. Intimal growth appeared primarily due to cell migration and matrix accumulation, with only a negligible contribution from cell proliferation. Overexpression of TGF-beta1 also stimulated expression of plasminogen activator inhibitor type 1 (plasminogen activator inhibitor [PAI]-1) in the artery wall. To test the hypothesis that PAI-1 is a critical downstream mediator of TGF-beta1-induced intimal growth, we transduced carotid arteries of PAI-1-deficient (Serpine1(-/-)) mice with the TGF-beta1-expressing vector. Overexpression of TGF-beta1 in Serpine1(-/-) arteries did not increase intimal growth, matrix accumulation, cell migration, or proliferation. Moreover, TGF-beta1-transduced arteries of Serpine1(-/-) mice secreted 6- to 10-fold more TGF-beta1 than did arteries of wild-type mice that were infused with the same concentration of the TGF-beta1-expressing vector.

CONCLUSIONS

PAI-1 is both a critical mediator of TGF-beta1-induced intimal growth and a key negative regulator of TGF-beta1 expression in the artery wall.

Nitric oxide regulates transforming growth factor-beta signaling in endothelial cells

Many forms of vascular disease are characterized by increased transforming growth factor (TGF)-beta1 expression and endothelial dysfunction. Smad proteins are a key step in TGF-beta-initiated signal transduction. We hypothesized that NO may regulate endothelial TGF-beta-dependent gene expression. We show that NO inhibits TGF-beta/Smad-regulated gene transactivation in a cGMP-dependent manner. NO effects were mimicked by a soluble analogue of cGMP. Inhibition of cGMP-dependent protein kinase 1 (PKG-1) or overexpression of dominant-negative PKG-1alpha suppressed NO/cGMP inhibition of TGF-beta-induced gene expression. Inversely, overexpression of PKG-1alpha catalytic subunit blocked TGF-beta-induced gene transactivation. Furthermore NO delayed and reduced phosphorylated Smad2/3 nuclear translocation, an effect mediated by PKG-1, whereas NG-nitro-L-arginine methyl ester augmented Smad phosphorylation and gene expression in response to TGF-beta. Aortas from endothelial NO synthase-deficient mice showed enhanced basal TGF-beta1 and collagen type I expression; endothelial cells from these animals showed increased Smad phosphorylation and transcriptional activity. Proteasome inhibitors prevented the inhibitory effect of NO on TGF-beta signaling. NO reduced the metabolic life of ectopically expressed Smad2 and enhanced its ubiquitination. Taken together, these results suggest that the endothelial NO/cGMP/PKG pathway interferes with TGF-beta/Smad2 signaling by directing the proteasomal degradation of activated Smad.

Kruppel-like factor 4 is a mediator of proinflammatory signaling in macrophages

Activation of macrophages is important in chronic inflammatory disease states such as atherosclerosis. Proinflammatory cytokines such as interferon-gamma (IFN-gamma), lipopolysaccharide (LPS), or tumor necrosis factor-alpha can promote macrophage activation. Conversely, anti-inflammatory factors such as transforming growth factor-beta1 (TGF-beta1) can decrease proinflammatory activation. The molecular mediators regulating the balance of these opposing effectors remain incompletely understood. Herein, we identify Kruppel-like factor 4 (KLF4) as being markedly induced in response to IFN-gamma, LPS, or tumor necrosis factor-alpha and decreased by TGF-beta1 in macrophages. Overexpression of KLF4 in J774a macrophages induced the macrophage activation marker inducible nitric-oxide synthase and inhibited the TGF-beta1 and Smad3 target gene plasminogen activator inhibitor-1 (PAI-1). Conversely, KLF4 knockdown markedly attenuated the ability of IFN-gamma, LPS, or IFN-gamma plus LPS to induce the iNOS promoter, whereas it augmented macrophage responsiveness to TGF-beta1 and Smad3 signaling. The KLF4 induction of the iNOS promoter is mediated by two KLF DNA-binding sites at -95 and -212 bp, and mutation of these sites diminished induction by IFN-gamma and LPS. We further provide evidence that KLF4 interacts with the NF-kappaB family member p65 (RelA) to cooperatively induce the iNOS promoter. In contrast, KLF4 inhibited the TGF-beta1/Smad3 induction of the PAI-1 promoter independent of KLF4 DNA binding through a novel antagonistic competition with Smad3 for the C terminus of the coactivator p300/CBP. These findings support an important role for KLF4 as a regulator of key signaling pathways that control macrophage activation.

Identification of intracellular pathways through which TGF-beta1 upregulates PAI-1 expression in endothelial cells

Upregulation of plasminogen activator inhibitor type 1 (PAI-1) expression is a critical mechanism through which transforming growth factor-beta1 (TGF-beta1) accelerates intimal growth. The aim of this study was to identify signaling pathways through which TGF-beta1 upregulates PAI-1 expression in endothelial cells (EC) and test interventions for blocking these pathways. We transduced cultured bovine EC with an adenoviral vector containing the PAI-1 promoter fused to a beta-galactosidase reporter gene. We used these cells, along with vectors expressing potential modifiers of TGF-beta1 signaling and pharmacologic antagonists of mitogen-activated protein kinase (MAPK) pathways to identify key mediators of basal and TGF-beta1-regulated PAI-1 expression. Basal activity of the PAI-1 promoter was directly correlated with Ras activation and was blocked by a dominant negative (DN) type I TGF-beta receptor. TGF-beta1-stimulated activity of the PAI-1 promoter did not require Ras activation, and was lessened or eliminated by expression of either DN type I or type II TGF-beta receptors and by inhibition of either of two MAPKs: MEK and p38. Our results suggest unanticipated pathways of TGF-beta1 signaling in EC and point to new strategies to limit TGF-beta1-induced vascular disease.

Dysfunctional Smad Signaling Contributes to Abnormal Smooth Muscle Cell Proliferation in Familial Pulmonary Arterial Hypertension

Mutations in the bone morphogenetic protein type II receptor gene (BMPR2) are the major genetic cause of familial pulmonary arterial hypertension (FPAH). Although smooth muscle cell proliferation contributes to the vascular remodeling observed in PAH, the role of BMPs in this process and the impact of BMPR2 mutation remains unclear. Studies involving normal human pulmonary artery smooth muscle cells (PASMCs) suggest site-specific responses to BMPs. Thus, BMP-4 inhibited proliferation of PASMCs isolated from proximal pulmonary arteries, but stimulated proliferation of PASMCs from peripheral arteries, and conferred protection from apoptosis. These differences were not caused by differential activation of BMP signaling pathways because exogenous BMP-4 led to phosphorylation of Smad1, p38(MAPK), and ERK1/2 in both cell types. However, the proproliferative effect of BMP-4 on peripheral PASMCs was found to be p38MAPK/ERK-dependent. Conversely, overexpression of dominant-negative Smad1 converted the response to BMP-4 in proximal PASMCs from inhibitory to proliferative. Furthermore, we confirmed that proximal PASMCs harboring kinase domain mutations in BMPR2 are deficient in Smad signaling and are unresponsive to the growth suppressive effect of BMP-4. Moreover, we show that the pulmonary vasculature of patients with familial and idiopathic PAH are deficient in the activated form of Smad1. We conclude that defective Smad signaling and unopposed p38(MAPK)/ERK signaling, as a consequence of mutation in BMPR2, underlie the abnormal vascular cell proliferation observed in familial PAH.

Smad6s regulates plasminogen activator inhibitor-1 through a protein kinase C-beta-dependent up-regulation of transforming growth factor-beta

Plasminogen activator inhibitor-1 (PAI-1) is a serpin class protease inhibitor that plays a central role in the regulation of vascular function and tissue remodeling by modulating thrombosis, inflammation, and the extracellular matrix. A central mediator controlling PAI-1 is transforming growth factor-beta (TGF-beta), which induces its expression and promotes fibrosis. We have found that a unique member of the Smad family of signal transduction molecules, Smad6s, modulates the expression of PAI-1. Overexpression of Smad6s in endothelial cells increases promoter activity and PAI-1 secretion, and an antisense to Smad6s suppresses the induction of PAI-1 by TGF-beta. The effect of Smad6s on the PAI-1 promoter appeared to be the result of increase binding of the forkhead winged helix factor FoxD1 to a TGF-beta-responsive element. Furthermore, the effect of Smad6s on PAI-1 up-regulation and on FoxD1 binding was found to result from up-regulation of TGF-beta and could be inhibited by the blocking TGF-beta signaling with Smad7. The ability of Smad6s to regulate the TGF-beta promoter and subsequent PAI-1 induction was suppressed by a selective protein kinase C-beta (PKC-beta) inhibitor. Consistent with the in vitro data, we found that increased Smad6s in diseased vessels correlated with increased TGF-beta and PAI-1 levels. Overall, our results demonstrate that the level of Smad6s can alter the level of TGF-beta and the subsequent induction of PAI-1 via a FoxD1 transcription site. Furthermore, our data suggest that this process, which is up-regulated in diseased vessels, can be modulated by the inhibition of PKC-beta.

Synthesis and activity of new aryl- and heteroaryl-substituted 5,6-dihydro-4H-pyrrolo[1,2-b]pyrazole inhibitors of the transforming growth factor-beta type I receptor kinase domain

We have expanded our previously reported series of pyrazole-based inhibitors of the TGF-beta type I receptor kinase domain (TbetaR-I) to now include new 5,6-dihydro-4H-pyrrolo[1,2-b]pyrazole analogues. Limited examination of the SAR of this new series in both enzyme and cell based in vitro assays has revealed selectivity differences with respect to p38 MAP kinase (p38 MAPK) depending on the nature of the 'warhead' group on the dihydropyrrolopyrazole ring. As with our original pyrazole series, phenyl substituents tended to show greater selectivity against p38 MAPK than those comprised of the quinoline-4-yl moiety. We have also achieved co-crystallization and X-ray analysis of compounds 3 and 15, two potent examples of this new series, with the TbetaR-I receptor kinase domain.