Smooth Muscle Migration Research Articles

Notch Transcriptional Control of Vascular Smooth Muscle Regulatory Gene Expression and Function

Notch receptors and ligands mediate heterotypic cell signaling that is required for normal vascular development. Dysregulation of select Notch receptors in mouse vascular smooth muscle (VSM) and in genetic human syndromes causes functional impairment in some regional circulations, the mechanistic basis of which is undefined. In this study, we used a dominant-negative Mastermind-like (DNMAML1) to block signaling through all Notch receptors specifically in VSM to more broadly test a functional role for this pathway in vivo. Mutant DNMAML1-expressing mice exhibited blunted blood pressure responses to vasoconstrictors, and their aortic, femoral, and mesenteric arteries had reduced contractile responses to agonists and depolarization in vitro. The mutant arteries had significant and specific reduction in the expression and activity of myosin light chain kinase (MLCK), a primary regulator of VSM force production. Conversely, activated Notch signaling in VSM cells induced endogenous MLCK transcript levels. We identified MLCK as a direct target of activated Notch receptor as demonstrated by an evolutionarily conserved Notch-responsive element within the MLCK promoter that binds the Notch receptor complex and is required for transcriptional activity. We conclude that Notch signaling through the transcriptional control of key regulatory proteins is required for contractile responses of mature VSM. Genetic or pharmacological manipulation of Notch signaling is a potential strategy for modulating arterial function in human disease.

G-Protein–Coupled Receptor Kinase Interacting Protein-1 Mediates Intima Formation by Regulating Vascular Smooth Muscle Proliferation, Apoptosis, and Migration

The G-protein-coupled receptor kinase interacting protein-1 (GIT1) is a scaffold protein that is important for phospholipase Cγ and extracellular signal-regulated kinase 1/2 signaling induced by angiotensin II and epidermal growth factor. Because GIT1 regulates signaling by several vascular smooth muscle cell (VSMC) growth factors, we hypothesized that intima formation would be inhibited by GIT1 depletion. Complete carotid ligation was performed on GIT1 wild-type and knockout (KO) mice. We compared changes between GIT1 wild-type and KO mice in carotid vascular remodeling, VSMC proliferation, and apoptosis in vivo and in vitro. Our data demonstrated that GIT1 deficiency significantly decreased intima formation after carotid ligation as a result of both reduced VSMC proliferation and enhanced apoptosis. To confirm the effects of GIT1 in vitro, we performed proliferation and apoptosis assays in VSMC. In mouse aortic smooth muscle cells (MASM), we found that the growth rate and [3H]-thymidine incorporation of the GIT1 KO MASM were significantly decreased compared with the wild-type MASM. Cyclin D1, which is a key cell cycle regulator, was significantly decreased in GIT1 KO cells. Serum deprivation of GIT1 KO MASM increased apoptosis 3-fold compared with wild-type MASM. Treatment of rat aortic smooth muscle cells with GIT1 small interfering RNA impaired cell migration. Both phospholipase Cγ and extracellular signal-regulated kinase 1/2 signaling were required for GIT1-dependent VSMC proliferation and migration, whereas only phospholipase Cγ was involved in GIT1-mediated VSMC apoptosis. GIT1 is a novel mediator of vascular remodeling by regulating VSMC proliferation, migration, and apoptosis through phospholipase Cγ and extracellular signal-regulated kinase 1/2 signaling pathways.

Substrate-Guided Proteomics Enhances Degradome Resolution

High-throughput technologies offer unrecognized insights into the genesis of human disease, propelling innovation across a spectrum of biomedical specialties.1 The evolution of molecular diagnostics continues to shape deployment of modern therapies, including identification of markers of disease prognosis, predictors of therapeutic response, and determinants of optimal clinical management, all recognized cornerstones of modern medical practice.2 In the postgenomic era, proteomic paradigms have demonstrated particular utility in advancing the practice of personalized disease prediction, diagnosis, and therapy,3 with systems-based approaches facilitating functional deconvolution of proteomes despite their inherent biological complexity.4 The ever-expanding proteomics toolkit encompasses an array of sophisticated technologies with the flexibility to interrogate a totality of putative protein targets, thereby enabling systematic resolution of proteome structures and functions. Indeed, mapping and decoding of proteome landscapes in health and disease provide the foundation to iteratively collate, integrate, and prioritize large-scale raw data.5 Thus, high-throughput proteomics offers a robust, adaptable technological foundation from which to systematically comprehend the underpinnings of (patho)physiological processes. Article see p 106 Innovative proteomic methods are designed to separate and identify proteins with high fidelity and to assess protein abundance, structure, posttranslational modifications, and interactions, enabling charting of the global proteome (ie, the protein complement of a genome; Figure). Progress in proteomic research has benefitted from the application of stringent criteria in assigning peptide and protein identities for comprehensive proteome cartography, such that perturbed or modified subproteomes within reconstituted protein networks can now be extracted at unprecedented rates for interpretation of their biological relevance. Expansion of proteomic studies has also been propelled by the concomitant development of high-resolution, high-mass-accuracy instrumentation, together with next-generation bioinformatics platforms for data analysis and systems interpretation. Existing approaches, however, may fall short of offering adequate experimental solutions arising from particular protein physicochemical constraints, limiting the otherwise far-reaching …

Effects of high mobility group protein box 1 on proliferation, migration and apoptosis of human pulmonary artery smooth muscle cells in vitro

Objective To evaluate the effects of high mobility group protein box 1 (HMGB1) on the proliferation,migration and apoptosis of human pulmonary artery smooth muscle cells (hPASMCs) in vitro.Methods The hPASMCs were seeded in 96-well plates in DMEM liquid culture medium (100 μl/well) with the density of 2 × 105/ml,in 6-well plate (1 ml/well) with the density of 2 × 106/ml or in modified 24-well Boyden chamber (100 μl/well) with the density of 5 × 103/ml and randomly divided into 5 groups (n =26 each):control group (group C) and 4 different concentrations of HMGB1 groups (groups H1-H4).The cells were cultured in DMEM liquid culture medium in group C.The cells were cultured in DMEM liquid culture medium containing HMGB1 1,10,100 and 1000 ng/ml in groups H1-H4,respectively.At 24 and 48 h of incubation,the proliferation,migration and apoptosis of hPASMCs were detected by MTT,modified Boyden chamber assay,and TUNEL,respectively.Results Compared with group C,the proliferation and migration of hPASMCs were significantly increased in groups H1-H4 (P ＜ 0.05).The proliferation of hPASMCs was significantly higher in groups H2-H4,and the migration of hPASMCs was higher in groups H3 and H4 than in group H1,and in groups H3 and H4 than in group H2 (P ＜ 0.05).There was no significant difference in the parameters mentioned above between groups H3 and H4 (P ＞ 0.05).The proliferation of hPASMCs was significantly higher at 48 h of incubation than at 24 h of incubation (P ＜ 0.05).There was no significant difference in the apoptotic rate between the five groups (P ＞ 0.05).Conclusion HMGB1 can induce the proliferation and migration of hPASMCs in vitro,which may be involved in pulmonary vascular remodeling during acute lung injury. Key words: High mobility group protein box 1 ; Muscle cells, smooth muscle; Cell proliferation; Cell movement; Apoptosis

Inhibition of Matrix Metalloproteinases (MMPs) as a Potential Strategy to Ameliorate Hypertension-Induced Cardiovascular Alterations

A group of proteases, the matrix metalloproteinases (MMPs) are well known for their capacity to degrade extracellular matrix (ECM) proteins. Particularly MMP-2 and MMP-9 contribute to the degradation and reorganization of the ECM components and are involved in the pathophysiology of cardiovascular remodeling. Imbalanced MMP activity promotes vascular smooth muscle cells and migration and proliferation and endothelial dysfunction, thus resulting in increased cardiovascular stiffness and hypertrophy. Furthermore, MMP-2 cleaves non-ECM protein substrates including cellular receptors and intracellular proteins, thus causing cardiac and vascular dysfunction. It is now becoming clear that increased MMP activity promotes long-lasting cardiovascular structural and functional alterations in both experimental and clinical hypertension, and this alteration may contribute to sustained hypertension and its complications. Other pathogenic mechanisms including activation of the renin-angiotensin-aldosterone system and oxidative stress activate and upregulate MMPs. Therefore, MMP inhibition may prevent the deleterious consequences of hypertension to the cardiovascular system. This review article will focus on growing evidence supporting the relevance of MMPs in hypertension and the effects of MMP inhibitors. Particularly, the effects of doxycycline used as a non selective MMP inhibitor in experimental and clinical studies will be discussed.

YKL-40 Induces IL-8 Expression from Bronchial Epithelium via MAPK (JNK and ERK) and NF-κB Pathways, Causing Bronchial Smooth Muscle Proliferation and Migration

Recently, the serum levels of YKL-40, a chitinase-like glycoprotein, have been shown to be significantly elevated in asthmatics and are associated with asthma severity. Although these studies raise the possibility that YKL-40 may influence asthma, the mechanisms remain unknown. This study firstly investigated the mechanisms involved in YKL-40-mediated inflammation in human bronchial epithelial cells (HBECs) and analyzed the soluble factors secreted by bronchial epithelial cells exposed to YKL-40 that were responsible for increasing proliferation and migration of primary normal human bronchial smooth muscle cells (BSMCs). YKL-40-induced inflammation was assayed in two HBECs (BEAS-2B cell line and primary HBECs). In addition, we treated BEAS-2B cells and HBECs with YKL-40 and added the conditioned culture media to BSMCs. The proliferation and migration of BSMCs were determined by premixed WST-1 cell proliferation reagent (Clontech Laboratories) and QCM chemotaxis migration assay (Millipore), respectively. Bronchial epithelial cells treated with YKL-40 resulted in a significant increase of IL-8 production, which was dependent on MAPK (JNK and ERK) and NF-κB pathways activation. YKL-40-induced IL-8 was found to further stimulate proliferation and migration of BSMCs, and the effects were inhibited after neutralizing IL-8. Through investigating the interaction of airway epithelium and smooth muscle, our findings implicate that YKL-40 may be involved in the inflammation of asthma by induction of IL-8 from epithelium, subsequently contributing to BSMC proliferation and migration. Moreover, inhibition of IL-8 signaling is a potential therapeutic target for YKL-40-induced inflammation and remodeling of asthma.

ENOS Glu298Asp polymorphism is associated with development of complicated plaques in patients from Serbia with advanced carotid atherosclerosis

Nitric oxide inhibits adhesion of thrombocytes, proliferation and migration of smooth muscle cells and restricts oxidation of atherogenic low-density lipoproteins. Therefore, decreased production or activity of NO may play a role in the initiation, progression or complications of atherosclerosis. The aim of this study was to estimate the effect of Glu298Asp eNOS gene polymorphism on the individual risk for development of complicated carotid atherosclerotic plaque in patients from Serbia with advanced carotid atherosclerosis (CA) who had undergone endarterectomy. The study population included 233 patients. eNOS G894T gene polymorphism was identified by PCR and RFLP methods. Multivariate logistic regression analysis showed that Asp298Asp is an independent risk factor for the presence of complicated plaques in CA patients. Patients who were homozygous for the Asp298 allele had an adjusted OR of 4.36 for the development of complicated plaques compared to those that carry the Glu298 allele. Further validation and replication studies are needed.

Differential Regulation of Airway Smooth Muscle Cell Migration by E-Prostanoid Receptor Subtypes

Migration of airway smooth muscle (ASM) cells plays an important role in the pathophysiology of airway hyperresponsiveness and remodeling in asthma. It has been reported that prostaglandin (PG)E2 inhibits migration of ASM cells. Although PGE2 regulates cellular functions via binding to distinct prostanoid EP receptors, the role of EP receptor subtypes in mechanisms underlying cell migration has not been fully elucidated. We investigated the role of EP receptors in the inhibitory effects of PGE2 on the migration of human ASM cells. Migration induced by platelet-derived growth factor (PDGF)-BB (10 ng/ml, 6 h) was assessed by a chemotaxis chamber assay. PDGF-BB-induced cell migration was inhibited by PGE2, the specific EP2 agonist ONO-AE1-259-01, the specific EP4 agonist ONO-AE1-329, and cAMP-mobilizing agents. The inhibition of cell migration by PGE2 was significantly reversed by a blockade of EP2 and EP4 receptors using antagonists or transfection with siRNAs. Moreover, PGE2, the EP2 agonist, and the EP4 agonist significantly increased phosphorylation of small heat shock protein 20, one of the protein substrates for protein kinase A (PKA), with depolymerization of actin. In contrast, the EP3 agonist ONO-AE-248 significantly promoted baseline cell migration without affecting PDGF-BB-induced cell migration. In summary, activation of EP2 and EP4 receptors and subsequent activation of the cAMP/PKA pathway are the main mechanisms of inhibition of ASM cell migration by PGE2. HSP20 phosphorylation by PKA is possibly involved in this mechanism. Conversely, EP3 is potent in promoting cell migration. EP receptor subtypes may be novel therapeutic target molecules in airway remodeling and asthma.

A Critical Review of the Use of Carvedilol in Ischemic Heart Disease

β-Adrenergic receptor antagonists (β-blockers) have been recognized for their cardioprotective properties, prompting use of these pharmacologic agents to become more mainstream in acute myocardial infarction (AMI) and congestive heart failure (CHF). Despite their popularity as a class, the ability to protect the myocardium varies significantly between different agents. Carvedilol is a non-selective β-blocker with α₁-adrenergic receptor antagonism properties. It is unique among β-blockers because in addition to improving exercise tolerance and its anti-ischemic properties secondary to a reduction in heart rate and myocardial contractility, carvedilol exerts other beneficial effects including: antioxidant effects; reduction in neutrophil infiltration; apoptosis inhibition; reduction of vascular smooth muscle migration; and improvement of myocardial remodeling post-AMI. These properties, documented in animal models and subsequent clinical trials, are consistent with established evidence demonstrating decreased morbidity and mortality in patients with CHF and post-AMI. This article reviews the role of carvedilol compared with other β-blockers in the treatment of CHF and post-AMI management.

AMP-activated protein kinase inhibits vascular smooth muscle cell proliferation and migration and vascular remodeling following injury

Vascular smooth muscle cell (VSMC) activation promotes a synthetic phenotype that underlies many vessel growth disorders. In this regard it has been suggested that the metabolic sensor adenosine 5'-monophosphate-activated protein kinase (AMPK) has significant antigrowth and antimetastatic properties and may serve as a viable therapeutic target. In the current study we hypothesized that AMPK reduces neointima formation following balloon injury and that this occurs through reduction in VSMC proliferation and migration. Data reveal that local or systemic dosing with the AMPK agonist 5-aminoimidazole-4-carboxamide-1-β-d-ribofuranoside (AICAR) significantly increased AMPK activity in vivo and inhibited neointima formation in rat carotid arteries 2 wk after injury. In primary VSMCs, AICAR inhibited migration and induced cytostatic growth arrest through increased protein phosphatase 2A-mediated inhibition of mitosis-promoting cyclin B. AICAR also significantly enhanced AMPK-specific T278 phosphorylation of the actin anticapping vasodilator-activated serum phosphoprotein, increased G- to F-actin ratios and stress fiber formation, and abrogated PDGF-stimulated S397 autophosphorylation of focal adhesion kinase, promigratory cytoplasmic accumulation of paxillin, and extracellular matrix proteolysis by matrix metalloproteinase-9. Together, these results provide compelling evidence that AMPK serves to inhibit vascular smooth muscle migration and proliferation through regulation of cytoskeletal/focal adhesion/ECM stability, increasing our knowledge of this important metabolic regulator and providing support for its continued investigation in the treatment of vascular growth disorders.

Abstract 18681: Molecular Imaging of Angiogenesis in Atherosclerosis Using a Caspase 3 Targeted PET Tracer 18 F-CP18

Background: Rupture of unstable coronary artery plaque results in luminal thrombosis and myocardial infarction. Smooth muscle migration, neovascularization and apoptosis are believed to constitute key steps that precede plaque rupture. Identification of plaque with enhanced apoptosis may therefore allow differentation of stable from high-risk plaque. We have developed [ 18 F]CP18, a PET tracer that is cleaved by caspase 3, a terminal enzyme in the apoptosis cascade. We sought to test the ability of this tracer to detect plaque apoptosis in an ApoE double knockout mouse model of atherosclerosis. Methods: ApoE knockout mice (n=6) were fed a high fat western diet for 30 weeks at the end of which 250µCi of 18 F-CP18 was injected intravenously. Mice were sacrificed 60 min post-injection and the aorta was excised. Ex-vivo autoradiography was performed using either whole aorta or 10 µm-thick transverse sections of the aorta mounted on glass slides. Apoptotic activity and plaque inflammation in tissue sections from similar locations in the aorta were visually assessed using TUNEL staining and CD68 antibody staining respectively. Lipid deposition was visualized by oil red O staining with an H&E counterstain. Results: In the ApoE KO mice fed a high fat diet, atherosclerotic plaque visualized by Oil Red O was present in the aortic root and aortic arch. Qualitative analysis of ex-vivo autoradiography of the aorta showed preferential uptake of 18 F-CP18 by aortic plaque at these same locations. Tunel staining and CD68 staining co-localized with plaques that exhibited increased 18 F-CP18 uptake. In contrast, in ApoE mice fed a regular diet and in wild-type mice fed the high-fat diet, there were fewer plaques in the aorta, with minimal tracer uptake and negligible histochemical evidence of macrophage influx and apoptotic activity. Conclusion: We were able to label a caspase 3 substrate CP18 with 18 F by click chemistry. Preliminary studies demonstrate that uptake of this tracer in aortic plaque strongly correlates with high levels of apoptotic activity by TUNEL staining and macrophage entry detected by CD68 staining. 18 F-CP18 may be a valuable imaging agent to detect plaque apoptosis and may allow early detection of hig-risk plaque.

Abstract 9922: The Induction of YAP Expression Following Arterial Injury is Crucial for Smooth Muscle Phenotypic Modulation and Neointima Formation

Rationale: Abnormal proliferation and migration of vascular smooth muscle cells (SMCs) are the key events in the progression of neointimal formation in response to vascular injury. Previous studies have shown that YAP is a potent oncogene promoting cell migration and proliferation, while the role of YAP in vascular diseases remain unknown. Objective: The goal of this study is to investigate the functional role of YAP in smooth muscle phenotypic modulation in vitro and in vivo. Methods and Results: In vitro in cell culture and in vivo in both mouse and rat arterial injury models YAP expression is significantly induced and correlated with the vascular SMC synthetic phenotype. YAP is also highly expressed in human carotid atherosclerotic plaque and localized in the majority of SMCs. Over-expression of YAP promotes SMC migration and proliferation while attenuating smooth muscle contractile gene expression. Conversely, knocking-down endogenous YAP in SMCs up-regulates smooth muscle gene expression but attenuates SMC proliferation and migration. Consistent with this, knocking-down YAP expression in a rat carotid balloon injury model attenuates injury-induced smooth muscle dedifferentiation and neointima formation. Furthermore, carotid artery ligation in mice with genetic deletion of YAP specifically in SMCs leads to increase smooth muscle-specific gene expression and reduction of neointima formation. Conclusion: YAP plays a novel integrative role in smooth muscle phenotypic modulation by inhibiting smooth muscle-specific gene expression while promoting smooth muscle proliferation and migration in vitro and in vivo. Blocking the induction of YAP would be a potential therapeutic approach for ameliorating vascular occlusive diseases.

STIM1 Regulates Platelet-Derived Growth Factor-Induced Migration and Ca2+ Influx in Human Airway Smooth Muscle Cells

It is suggested that migration of airway smooth muscle (ASM) cells plays an important role in the pathogenesis of airway remodeling in asthma. Increases in intracellular Ca2+ concentrations ([Ca2+]i) regulate most ASM cell functions related to asthma, such as contraction and proliferation. Recently, STIM1 was identified as a sarcoplasmic reticulum (SR) Ca2+ sensor that activates Orai1, the Ca2+ channel responsible for store-operated Ca2+ entry (SOCE). We investigated the role of STIM1 in [Ca2+]i and cell migration induced by platelet-derived growth factor (PDGF)-BB in human ASM cells. Cell migration was assessed by a chemotaxis chamber assay. Human ASM cells express STIM1, STIM2, and Orai1 mRNAs. SOCE activated by thapsigargin, an inhibitor of SR Ca2+-ATPase, was significantly blocked by STIM1 siRNA and Orai1 siRNA but not by STIM2 siRNA. PDGF-BB induced a transient increase in [Ca2+]i followed by sustained [Ca2+]i elevation. Sustained increases in [Ca2+]i due to PDGF-BB were significantly inhibited by a Ca2+ chelating agent EGTA or by siRNA for STIM1 or Orai1. The numbers of migrating cells were significantly increased by PDGF-BB treatment for 6 h. Knockdown of STIM1 and Orai1 by siRNA transfection inhibited PDGF-induced cell migration. Similarly, EGTA significantly inhibited PDGF-induced cell migration. In contrast, transfection with siRNA for STIM2 did not inhibit the sustained elevation of [Ca2+]i or cell migration induced by PDGF-BB. These results demonstrate that STIM1 and Orai1 are essential for PDGF-induced cell migration and Ca2+ influx in human ASM cells. STIM1 could be an important molecule responsible for airway remodeling.

Protein Disulfide Isomerase Is Required for Platelet-derived Growth Factor-induced Vascular Smooth Muscle Cell Migration, Nox1 NADPH Oxidase Expression, and RhoGTPase Activation

Vascular Smooth Muscle Cell (VSMC) migration into vessel neointima is a therapeutic target for atherosclerosis and postinjury restenosis. Nox1 NADPH oxidase-derived oxidants synergize with growth factors to support VSMC migration. We previously described the interaction between NADPH oxidases and the endoplasmic reticulum redox chaperone protein disulfide isomerase (PDI) in many cell types. However, physiological implications, as well as mechanisms of such association, are yet unclear. We show here that platelet-derived growth factor (PDGF) promoted subcellular redistribution of PDI concomitant to Nox1-dependent reactive oxygen species production and that siRNA-mediated PDI silencing inhibited such reactive oxygen species production, while nearly totally suppressing the increase in Nox1 expression, with no change in Nox4. Furthermore, PDI silencing inhibited PDGF-induced VSMC migration assessed by distinct methods, whereas PDI overexpression increased spontaneous basal VSMC migration. To address possible mechanisms of PDI effects, we searched for PDI interactome by systems biology analysis of physical protein-protein interaction networks, which indicated convergence with small GTPases and their regulator RhoGDI. PDI silencing decreased PDGF-induced Rac1 and RhoA activities, without changing their expression. PDI co-immunoprecipitated with RhoGDI at base line, whereas such association was decreased after PDGF. Also, PDI co-immunoprecipitated with Rac1 and RhoA in a PDGF-independent way and displayed detectable spots of perinuclear co-localization with Rac1 and RhoGDI. Moreover, PDI silencing promoted strong cytoskeletal changes: disorganization of stress fibers, decreased number of focal adhesions, and reduced number of RhoGDI-containing vesicular recycling adhesion structures. Overall, these data suggest that PDI is required to support Nox1/redox and GTPase-dependent VSMC migration.

DHEA-S inhibits human neutrophil and human airway smooth muscle migration

Airway diseases such as asthma, emphysema, and chronic bronchitis are, in part, characterized by reversible airflow obstruction and inflammation. In severe disease, marked decreases in lung function are associated with airway smooth muscle proliferation and airway neutrophilia. Inhaled glucocorticoids attenuate increased airflow obstruction and airway inflammation that occur, in part, due to increased smooth muscle migration and proliferation, as well as the airway neutrophilia. Glucocorticoids, however, have adverse side effects and, in some patients, are ineffective despite high doses. Recent research has explored the effects of non-traditional steroids on attenuation of inflammation associated with airway diseases. These non-traditional steroids have improved side effect profiles in comparison to glucocorticoid therapy. Our studies assessed effects of dehydroepiandrosterone-3-sulfate (DHEA-S) on migration of both human peripheral blood neutrophils (PMN) and human airway smooth muscle cells (HASM). DHEA-S dose-dependently inhibited chemotaxis of PMN and HASM while having no effect on the phosphorylation levels of Akt, ERK1/2, p38 MAPK or PKC, canonical positive regulators of cell migration. These studies demonstrate direct effects of DHEA-S on cell migration, thereby suggesting that DHEA-S may attenuate airway inflammation and cell migration.

Intimal hyperplasia: slow but deadly

Intimal hyperplasia is the leading cause of long-term failure in coronary artery bypass vein grafting, coronary artery stenting, angioplasty, arteriovenous fistula for dialysis, and allograft transplantation. Intimal hyperplasia is a product of vascular smooth muscle cell proliferation, migration through the internal elastic lamina, and deposition of extracellular matrix proteins driven by growth factors in the vasculature. This vascular pathology results in a progressive diminution of the vessel lumen and serves as a site for thrombosis and atherosclerotic lesions. A key cell type in the initiation of intimal hyperplasia is the vascular endothelial cell, which appears to have down-stream effects on the vascular smooth muscle proliferation and migration. Currently, the only means available for prevention of intimal hyperplasia is through inhibition of mammalian target of rapamycin (mTOR) with the immunosuppressant rapamycin. mTOR integrates up-stream signals from growth factors such as IL-2 and senses the cellular nutrient and energy levels and redox status. This presentation will discuss the potential means of preserving the vascular endothelial cell and, thereby, reducing the development of intimal hyperplasia in our open-heart surgical patients.

PPAR ligands decrease human airway smooth muscle cell migration and extracellular matrix synthesis

Airway smooth muscle cells produce extracellular matrix proteins, which in turn can promote smooth muscle survival, proliferation and migration. Currently available therapies have little effect on airway smooth muscle matrix production and migration. Peroxisome proliferator-activated receptor (PPAR) ligands are reported to decrease migration and matrix production in various cell lines. In this study, we examined the effect of PPAR ligands on human airway smooth muscle (HASM) matrix production and migration. PPAR expression was examined by RT-PCR and Western blotting. Endogenous PPAR activity was examined by transfecting cells with a PPAR response element-luciferase reporter plasmid. We observed that HASM cells express PPARα, β and γ. A six-fold induction of luciferase activity was observed by stimulating cells with a pan-agonist, indicating endogenous PPAR activity. The PPAR ligands ciglitazone, 15-deoxy-Δ12,14-prostaglandin J(2) and WY-14643 decreased migration towards platelet-derived growth factor receptor. This was not mediated by inhibiting Akt phosphorylation or promoting PTEN activity, but partly through cyclooxygenase-2 induction and prostaglandin E(2) production that increased cyclic AMP levels in the cells. All three ligands also caused an inhibition of collagen and fibronectin secretion by cultured smooth muscle cells. We conclude that PPAR ligands decrease HASM migration and matrix production and are, therefore, potentially useful for modulating airway remodelling.

Abstract 525: Reduced Ability of Endothelial Progenitor Cells to Inhibit Smooth Muscle Cell Proliferation and Migration Compared to Aortic Endothelial Cells Under Flow

Early endothelial restoration at sites of vascular intervention is one of the recognized important potential treatment strategies that can be exploited to limit arterial restenosis associated with intimal smooth muscle cell hyperplasia. In recent years, much attention has been focused on the potential of circulating bone marrow derived cells named endothelial progenitor cells (EPC) to differentiate into mature endothelial cells upon attachment at injured vascular sites and, thereby, potentially limit intimal hyperplasia. Our objective was to compare the influence of isolated porcine blood EPC and aortic endothelial cells (HAEC) on the proliferation and migration of underlying aortic smooth muscle (SMC) cells using a novel arterial wall model system exposed to arterial flow patterns. An in vitro arterial wall model co-culture system was constructed as the bottom plate within a parallel plate flow chamber. A 2mm thick collagen gel containing porcine SMC was overlayed by a porous (5μm) polyester mesh. After 2 days, either porcine aortic EC or CD34+ EPC or no cells (control) were seeded on the surface and allowed to attain confluence. These constructs were then placed into a flow chamber and exposed to arterial flow (12 dynes/cm 2 ) for 48h using circulating culture medium. After the flow regimen, SMC that had migrated through the mesh were immunologically identified and counted. The mesh was removed and the percent proliferating cells in the underlying gel were identified by PCNA staining.EC coverage resulted in an almost 7-fold inhibition of SMC migration compared to control (127±33 vs 840±193 SMC/cm 2 ) and more than 4- fold more than observed with EPC coverage (553±7 SMC/cm 2 ). Similarly, EC coverage resulted in reducing SMC proliferation to 3.2% compared to 8.5% in EPC covered SMC and 14% PCNA positive SMC in the control underlying SMC. These result indicate that blood-derived CD34+ EPC are less effective in limiting adjacent SMC proliferation and migration than native arterial endothelial cells. This may have important implications for strategies designed to employ or attract these cells as a means to limit restenosis at stented interventional sites.

Pentraxin 3 (PTX3) Expression in Allergic Asthmatic Airways: Role in Airway Smooth Muscle Migration and Chemokine Production

BackgroundPentraxin 3 (PTX3) is a soluble pattern recognition receptor with non-redundant functions in inflammation and innate immunity. PTX3 is produced by immune and structural cells. However, very little is known about the expression of PTX3 and its role in allergic asthma.Objectives and MethodsWe sought to determine the PTX3 expression in asthmatic airways and its function in human airway smooth muscle cells (HASMC). In vivo PTX3 expression in bronchial biopsies of mild, moderate and severe asthmatics was analyzed by immunohistochemistry. PTX3 mRNA and protein were measured by real-time RT-PCR and ELISA, respectively. Proliferation and migration were examined using 3H-thymidine incorporation, cell count and Boyden chamber assays.ResultsPTX3 immunoreactivity was increased in bronchial tissues of allergic asthmatics compared to healthy controls, and mainly localized in the smooth muscle bundle. PTX3 protein was expressed constitutively by HASMC and was significantly up-regulated by TNF, and IL-1β but not by Th2 (IL-4, IL-9, IL-13), Th1 (IFN-γ), or Th-17 (IL-17) cytokines. In vitro, HASMC released significantly higher levels of PTX3 at the baseline and upon TNF stimulation compared to airway epithelial cells (EC). Moreover, PTX3 induced CCL11/eotaxin-1 release whilst inhibited the fibroblast growth factor-2 (FGF-2)-driven HASMC chemotactic activity.ConclusionsOur data provide the first evidence that PTX3 expression is increased in asthmatic airways. HASMC can both produce and respond to PTX3. PTX3 is a potent inhibitor of HASMC migration induced by FGF-2 and can upregulate CCL11/eotaxin-1 release. These results raise the possibility that PTX3 may play a dual role in allergic asthma.

Targeting Soluble Epoxide Hydrolase for Inflammation and Pain - An Overview of Pharmacology and the Inhibitors

Chronic inflammation is an important contributing factor to a variety of human diseases including rheumatoid arthritis, inflammatory bowel disease, psoriasis and atherosclerosis. Epoxidation of arachidonic acid by cytochrome P450 enzymes during inflammation yields epoxyeicosatrienoic acids (EETs). EETs have a variety of biological effects including modulation of inflammation, vascular smooth muscle migration and platelet aggregation. The EETs levels are regulated by soluble epoxide hydrolase (sEH), the major enzyme responsible for their degradation and conversion to inactive dihydroxyeicosatrienoic acids (DHETs); thereby limiting many of the biological actions of EETs. The molecular and pharmacological inhibition of sEH has been studied extensively for benefits on the cardiovascular system. More recent studies suggest the importance of EETs and sEH in pain and inflammation. This review will discuss the current status and emerging evidence on the role of sEH and sEH inhibitors in chronic inflammatory conditions such as atherosclerosis, colitis and arthritis. Although steroids and non-steroidal anti-inflammatory drugs are effective, their chronic use is limited by the metabolic and cardiovascular side effects. Currently there are no small molecule drugs for treatment of chronic inflammation and associated pain and sEH inhibitors with their intrinsic cardiovascular protective effects can potentially fill this void.