Overexpression of mutated IkappaBalpha inhibits vascular smooth muscle cell proliferation and intimal hyperplasia formation

Vascular smooth muscle cells in intimal hyperplasia, an update

Arterial occlusive disease is the leading cause of death in Western countries. Core contemporary therapies for this disease include angioplasties, stents, endarterectomies and bypass surgery. However, these treatments suffer from high failure rates due to re-occlusive vascular wall adaptations and restenosis. Restenosis following vascular surgery is largely due to intimal hyperplasia. Intimal hyperplasia develops in response to vessel injury, leading to inflammation, vascular smooth muscle cells dedifferentiation, migration, proliferation and secretion of extra-cellular matrix into the vessel's innermost layer or intima. In this review, we describe the current state of knowledge on the origin and mechanisms underlying the dysregulated proliferation of vascular smooth muscle cells in intimal hyperplasia, and we present the new avenues of research targeting VSMC phenotype and proliferation.

Identification of the Crucial Gene in Overflow Arteriovenous Fistula by Bioinformatics Analysis

Objective: The aim was to study the preliminary screening of the crucial genes in intimal hyperplasia in the venous segment of arteriovenous (AV) fistula and the underlying potential molecular mechanisms of intimal hyperplasia with bioinformatics analysis. Methods: The gene expression profile data (GSE39488) was analyzed to identify differentially expressed genes (DEGs). We performed Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis of DEGs. Gene set enrichment analysis (GSEA) was used to understand the potential activated signaling pathway. The protein-protein interaction (PPI) network was constructed with the STRING database and Cytoscape software. The Venn diagram between 10 hub genes and gene sets of 4 crucial signaling pathways was used to obtain core genes and relevant potential pathways. Furthermore, GSEAs were performed to understand their biological functions. Results: A total of 185 DEGs were screened in this study. The main biological function of the 111 upregulated genes in AV fistula primarily concentrated on cell proliferation and vascular remodeling, and the 74 downregulated genes in AV fistula were enriched in the biological function mainly relevant to inflammation. GSEA found four signaling pathways crucial for intimal hyperplasia, namely, MAPK, NOD-like, Cell Cycle, and TGF-beta signaling pathway. A total of 10 hub genes were identified, namely, EGR1, EGR2, EGR3, NR4A1, NR4A2, DUSP1, CXCR4, ATF3, CCL4, and CYR61. Particularly, DUSP1 and NR4A1 were identified as core genes that potentially participate in the MAPK signaling pathway. In AV fistula, the biological processes and pathways were primarily involved with MAPK signaling pathway and MAPK-mediated pathway with the high expression of DUSP1 and were highly relevant to cell proliferation and inflammation with the low expression of DUSP1. Besides, the biological processes and pathways in AV fistula with the high expression of NR4A1 similarly included the MAPK signaling pathway and the pathway mediated by MAPK signaling, and it was mainly involved with inflammation in AV fistula with the low expression of NR4A1. Conclusion: We screened four potential signaling pathways relevant to intimal hyperplasia and identified 10 hub genes, including two core genes (i.e., DUSP1 and NR4A1). Two core genes potentially participate in the MAPK signaling pathway and might serve as the therapeutic targets of intimal hyperplasia to prevent stenosis after AV fistula creation.

lncRNA KCNQ1OT1 Suppresses the Inflammation and Proliferation of Vascular Smooth Muscle Cells through IκBa in Intimal Hyperplasia

Inflammation and proliferation of vascular smooth muscle cells (VSMCs) are the key events in intimal hyperplasia. This study aimed to explore the mechanism by which long non-coding RNA (lncRNA) KCNQ1OT1 affects VSMC inflammation and proliferation in this context. A vein graft (VG) model was established in mice to introduce intimal hyperplasia. Isolated normal VSMCs were induced with platelet-derived growth factor type BB (PDGF-BB), and the cell proliferation, migration, and secretion of inflammatory factors were determined. The results showed that KCNQ1OT1 was downregulated in the VSMCs from mice with intimal hyperplasia and in the PDGF-BB-treated VSMCs, and such downregulation of KCNQ1OT1 resulted from the increased methylation level in the KCNQ1OT1 promoter. Overexpressing KCNQ1OT1 suppressed PDFG-BB-induced VSMC proliferation, migration, and secretion of inflammatory factors. In VSMCs, KCNQ1OT1 bound to the nuclear transcription factor kappa Ba (IκBa) protein and increased the cellular IκBa level by reducing phosphorylation and promoting ubiquitination of the IκBa protein. Meanwhile, KCNQ1OT1 promoted the expression of IκBa by sponging miR-221. The effects of KCNQ1OT1 knockdown on promoting VSMC proliferation, migration, and secretion of inflammatory factors were abolished by IκBa overexpression. The roles of KCNQ1OT1 in reducing the intimal area and inhibiting IκBa expression were proved in the VG mouse model after KCNQ1OT1 overexpression. In conclusion, KCNQ1OT1 attenuated intimal hyperplasia by suppressing the inflammation and proliferation of VSMCs, in which the mechanism upregulated IκBa expression by binding to the IκBa protein and sponging miR-221.

A novel function of FoxO transcription factors in thrombin-stimulated vascular smooth muscle cell proliferation

Thrombin exerts coagulation-independent effects on the proliferation and migration of vascular smooth muscle cells (SMC). Forkhead box-O (FoxO) transcription factors regulate cell proliferation, apoptosis and cell cycle arrest, but a possible functional interaction between thrombin and FoxO factors has not been identified to date. In human cultured vascular SMC, thrombin induced a time-dependent phosphorylation of FoxO1 and FoxO3 but not FoxO4. This effect was mimicked by an activating-peptide (AP) for protease-activated receptor (PAR)-1, and abolished by a PAR-1 antagonist (SCH79797). APs for other PARs were without effect. FoxO1 and FoxO3 phosphorylation were prevented by the PI3 kinase (PI3K) inhibitor LY294002 while inhibitors of ERK1/2 (PD98059) or p38MAPK (SB203580) were ineffective. LY294002 moreover prevented thrombin-stimulated SMC mitogenesis and proliferation. FoxO1 and FoxO3 siRNA augmented basal DNA synthesis and proliferation of SMC. Nuclear content of FoxO proteins decreased time-dependently in response to thrombin, coincided with suppressed expression of the cell cycle regulating genes p21CIP1 and p27kip1 by thrombin. FoxO1 siRNA reduced basal p21CIP1 while FoxO3 siRNA attenuated p27kip1 expression; thrombin did not show additive effects. LY294002 restored p21CIP1 and p27kip1 protein expression. Immunohistochemistry revealed that human native and failed saphenous vein grafts were characterised by the cytosolic presence of p-FoxO factors in co-localisation of p21CIP1 and p27kip1 with SMC. In conclusion, thrombin and FoxO factors functionally interact through PI3K/Akt-dependent FoxO phosphorylation leading to expression of cell cycle regulating genes and ultimately SMC proliferation. This may contribute to remodelling and failure of saphenous vein bypass grafts.

Comprehensive gene expression profiling reveals synergistic functional networks in cerebral vessels after hypertension or hypercholesterolemia

Atherosclerotic stenosis of cerebral arteries or intracranial large artery disease (ICLAD) is a major cause of stroke especially in Asians, Hispanics and Africans, but relatively little is known about gene expression changes in vessels at risk. This study compares comprehensive gene expression profiles in the middle cerebral artery (MCA) of New Zealand White rabbits exposed to two stroke risk factors i.e. hypertension and/or hypercholesterolemia, by the 2-Kidney-1-Clip method, or dietary supplementation with cholesterol. Microarray and Ingenuity Pathway Analyses of the MCA of the hypertensive rabbits showed up-regulated genes in networks containing the node molecules: UBC (ubiquitin), P38 MAPK, ERK, NFkB, SERPINB2, MMP1 and APP (amyloid precursor protein); and down-regulated genes related to MAPK, ERK 1/2, Akt, 26 s proteasome, histone H3 and UBC. The MCA of hypercholesterolemic rabbits showed differentially expressed genes that are surprisingly, linked to almost the same node molecules as the hypertensive rabbits, despite a relatively low percentage of ‘common genes’ (21 and 7%) between the two conditions. Up-regulated common genes were related to: UBC, SERPINB2, TNF, HNF4A (hepatocyte nuclear factor 4A) and APP, and down-regulated genes, related to UBC. Increased HNF4A message and protein were verified in the aorta. Together, these findings reveal similar nodal molecules and gene pathways in cerebral vessels affected by hypertension or hypercholesterolemia, which could be a basis for synergistic action of risk factors in the pathogenesis of ICLAD.

Smooth muscle-selective inhibition of nuclear factor-κB attenuates smooth muscle phenotypic switching and neointima formation following vascular injury

BACKGROUND

Vascular proliferative diseases such as atherosclerosis are inflammatory disorders involving multiple cell types including macrophages, lymphocytes, endothelial cells, and smooth muscle cells (SMCs). Although activation of the nuclear factor-κB (NF-κB) pathway in vessels has been shown to be critical for the progression of vascular diseases, the cell-autonomous role of NF-κB within SMCs has not been fully understood.

METHODS AND RESULTS

We generated SMC-selective truncated IκB expressing (SM22α-Cre/IκBΔN) mice, in which NF-κB was inhibited selectively in SMCs, and analyzed their phenotype following carotid injury. Results showed that neointima formation was markedly reduced in SM22α-Cre/IκBΔN mice after injury. Although vascular injury induced downregulation of expression of SMC differentiation markers and myocardin, a potent activator of SMC differentiation markers, repression of these markers and myocardin was attenuated in SM22α-Cre/IκBΔN mice. Consistent with these findings, NF-κB activation by interleukin-1β (IL-1β) decreased expression of SMC differentiation markers as well as myocardin in cultured SMCs. Inhibition of NF-κB signaling by BAY 11-7082 attenuated repressive effects of IL-1β. Of interest, Krüppel-like factor 4 (Klf4), a transcription factor critical for regulating SMC differentiation and proliferation, was also involved in IL-1β-mediated myocardin repression. Promoter analyses and chromatin immunoprecipitation assays revealed that NF-κB repressed myocardin by binding to the myocardin promoter region in concert with Klf4.

CONCLUSIONS

These results provide novel evidence that activation of the NF-κB pathway cell-autonomously mediates SMC phenotypic switching and contributes to neointima formation following vascular injury.

Vinpocetine suppresses pathological vascular remodeling by inhibiting vascular smooth muscle cell proliferation and migration

Abnormal vascular smooth muscle cell (SMC) activation is associated with various vascular disorders such as atherosclerosis, in-stent restenosis, vein graft disease, and transplantation-associated vasculopathy. Vinpocetine, a derivative of the alkaloid vincamine, has long been used as a cerebral blood flow enhancer for treating cognitive impairment. However, its role in pathological vascular remodeling remains unexplored. Herein, we show that systemic administration of vinpocetine significantly reduced neointimal formation in carotid arteries after ligation injury. Vinpocetine also markedly decreased spontaneous remodeling of human saphenous vein explants in ex vivo culture. In cultured SMCs, vinpocetine dose-dependently suppressed cell proliferation and caused G1-phase cell cycle arrest, which is associated with a decrease in cyclin D1 and an increase in p27Kip1 levels. In addition, vinpocetine dose-dependently inhibited platelet-derived growth factor (PDGF)-stimulated SMC migration as determined by the two-dimensional migration assays and three-dimensional aortic medial explant invasive assay. Moreover, vinpocetine significantly reduced PDGF-induced type I collagen and fibronectin expression. It is noteworthy that PDGF-stimulated phosphorylation of extracellular signal-regulated kinases 1/2 (ERK1/2), but not protein kinase B, was specifically inhibited by vinpocetine. Vinpocetine powerfully attenuated intracellular reactive oxidative species (ROS) production, which largely mediates the inhibitory effects of vinpocetine on ERK1/2 activation and SMC growth. Taken together, our results reveal a novel function of vinpocetine in attenuating neointimal hyperplasia and pathological vascular remodeling, at least partially through suppressing ROS production and ERK1/2 activation in SMCs. Given the safety profile of vinpocetine, this study provides insight into the therapeutic potential of vinpocetine in proliferative vascular disorders.

C-peptide reduces pro-inflammatory cytokine secretion in LPS-stimulated U937 monocytes in condition of hyperglycemia

OBJECTIVE

We investigated C-peptide effects on inflammatory cytokine release and adhesion of monocytes exposed to high glucose and lipopolysaccharide (LPS) in vitro.

MATERIALS AND METHODS

Monocytic cells (U-937) were cultured in the presence of 30 mmol/L glucose and stimulated with 0.5 ng/μL LPS in the presence or absence of C-peptide (1 μmol/L) for 24 h to induce inflammatory cytokine secretion. Adhesion of U-937 monocytes to human aortic endothelial cells (HAEC) was also studied in the presence or absence of C-peptide. Concentrations of IL-6, IL-8, macrophage inflammatory protein(MIP)-1α, and MIP-1β in supernatants from LPS-stimulated U-937 monocytes were assessed by Luminex. To gain insights into potential intracellular signaling pathways affected by C-peptide, we investigated nuclear translocation of nuclear factor(NF)-κB p65/p50 subunits by western blot in LPS-treated U-937 cells. The effect of C-peptide on LPS-induced phosphorylation of the cytoplasmic protein IκB-α was also investigated by immunoblotting.

RESULTS

Addition of C-peptide significantly reduced cytokine secretion from LPS-stimulated U-937 monocytes. Adhesion of U-937 cells to HAEC was also significantly reduced by C-peptide. These effects were accompanied by reduced NF-κB p65/p50 nuclear translocation and decreased phosphorylation of IκB-α.

CONCLUSIONS

We conclude that, in conditions of hyperglycemia, C-peptide reduces monocytes activation via inhibition of the NF-κB pathway.

O-GlcNAc modification of NFκB p65 inhibits TNF-α-induced inflammatory mediator expression in rat aortic smooth muscle cells

Background

We have shown that glucosamine (GlcN) or O-(2-acetamido-2-deoxy-D-glucopyranosylidene)amino-N-phenylcarbamate (PUGNAc) treatment augments O-linked-N-acetylglucosamine (O-GlcNAc) protein modification and attenuates inflammatory mediator expression, leukocyte infiltration and neointima formation in balloon injured rat carotid arteries and have identified the arterial smooth muscle cell (SMC) as the target cell in the injury response. NFκB signaling has been shown to mediate the expression of inflammatory genes and neointima formation in injured arteries. Phosphorylation of the p65 subunit of NFκB is required for the transcriptional activation of NFκB. This study tested the hypothesis that GlcN or PUGNAc treatment protects vascular SMCs against tumor necrosis factor (TNF)-α induced inflammatory stress by enhancing O-GlcNAcylation and inhibiting TNF-α induced phosphorylation of NFκB p65, thus inhibiting NFκB signaling.

Methodology/Principal Findings

Quiescent rat aortic SMCs were pretreated with GlcN (5 mM), PUGNAc (10⁻⁴ M) or vehicle and then stimulated with TNF-α (10 ng/ml). Both treatments inhibited TNF-α-induced expression of chemokines [cytokine-induced neutrophil chemoattractant (CINC)-2β and monocyte chemotactic protein (MCP)-1] and adhesion molecules [vascular cell adhesion molecule (VCAM)-1 and P-Selectin]. Both treatments inhibited TNF-α induced NFκB p65 activation and promoter activity, increased NFκB p65 O-GlcNAcylation and inhibited NFκB p65 phosphorylation at Serine 536, thus promoting IκBα binding to NFκB p65.

Conclusions

There is a reciprocal relationship between O-GlcNAcylation and phosphorylation of NFκB p65, such that increased NFκB p65 O-GlcNAc modification inhibits TNF-α-Induced expression of inflammatory mediators through inhibition of NFκB p65 signaling. These findings provide a mechanistic basis for our previous observations that GlcN and PUGNAc treatments inhibit inflammation and remodeling induced by acute endoluminal arterial injury.

The vascular adventitia: its role in the arterial injury response

The belief that the adventitia serves only a structural purpose has changed over the last decade. Studies have begun to elucidate the role the adventitia plays in the arterial response to injury. The adventitial fibroblast plays an integral part in the development of neointimal hyperplasia. Adiponectin, an adipokine produced from periadventitial adipose tissue, exhibits numerous vasoprotective properties. Stem cells arise, in part, from the adventitia, and stem cell recruitment into the adventitia from the vasa vasorum has been shown to be important in the development of neointimal hyperplasia. The exact role the vasa vasorum plays in neointimal growth is poorly understood and different studies endorse conflicting viewpoints. Thus, understanding the nuances of adventitial pathophysiology will allow us to better appreciate the mechanisms behind the pathology of neointimal hyperplasia. This review will summarize recent findings on the active role the adventitia plays toward the development of neointimal hyperplasia.

Preventive effect of a proteasome inhibitor on the formation of accelerated atherosclerosis in rabbits with uremia

Inflammation plays a central role in the pathogenesis of atherosclerosis. This study investigated whether the proteasome inhibitor has the same preventive effect on the formation of accelerated atherosclerosis in rabbits with uremia compared with a NF-kappaB inhibitor. New Zealand white rabbits were subjected to five-sixths nephrectomy (chronic renal failure [CRF]) or to a sham operation. Rats in each group were randomly assigned into three subgroups (n = 24 in each group) and treated with repeated intramuscular injections of proteasome inhibitor MG132 or NF-kappaB inhibitor PDTC for a specified period. Compared with sham rabbits, CRF rabbits displayed typical atherosclerotic changes (endothelial cell damage, intimal thickens, and appearance of foam cells). CRF rabbits had significantly higher levels of proteasome activity, NF-kappaB mRNA, protein, and DNA binding activity as well as tumor necrosis factor-a and proliferative cell nuclear antigen protein expression in aortic wall cells. CRF rabbits also showed lower levels of IkappaBalpha. Compared with CRF rabbits, CRF rabbits treatment with proteasome inhibitor MG132 showed restoration of IkappaBalpha mRNA and protein expression and decreased NF-kappaB DNA binding activity and tumor necrosis factor-a expression. Treatment with either proteasome inhibitor MG132 or NF-kappaB inhibitor PDTC could reverse these pathologic changes in the aortic wall cells of CRF rabbits. A comparison between the inhibitory effects of the two treatments revealed no statistical difference. These results suggest that ubiquitin-proteasome activation play a pivotal role in the pathogenesis of uremia-accelerated atherosclerosis. The ubiquitin-proteasome signaling pathway in aortic cells may therefore be an important target for preventing uremia-accelerated atherosclerosis.

A20 inhibits post-angioplasty restenosis by blocking macrophage trafficking and decreasing adventitial neovascularization

OBJECTIVE

Neointimal hyperplasia is an inflammatory and proliferative process that occurs as a result of injury to the vessel wall. We have shown that the homeostatic protein A20 prevents neointimal hyperplasia by affecting endothelial cell (EC) and smooth muscle cell (SMC) responses to injury. In this work, we questioned whether A20 impacts other pathogenic effectors of neointimal hyperplasia including homing of monocyte/macrophages and EC/SMC precursors to the site of vascular injury, vascular endothelial growth factor (VEGF) secretion, and adventitial neovascularization.

METHODS AND RESULTS

Carotid balloon angioplasty was performed on rat recipients of a bone marrow transplant from green fluorescent rats. Adenoviral delivery of A20 prevented neointimal hyperplasia and decreased macrophage infiltration. This was associated with decreased ICAM-1 and MCP-1 expression in vitro. Additionally, A20 reduced neovascularization in the adventitia of balloon injured carotid arteries, which correlated with fewer VEGF positive cells.

CONCLUSIONS

A20 downregulates adhesion markers, chemokine production, and adventitial angiogenesis, all of which are required for macrophage trafficking to sites of vascular injury. This, in turn, diminishes the inflammatory milieu to prevent neointimal hyperplasia.

Role of nuclear factor kappaB in cardiovascular health and disease

Cardiovascular pathologies are still the primary cause of death worldwide. The molecular mechanisms behind these pathologies have not been fully elucidated. Unravelling them will bring us closer to therapeutic strategies to prevent or treat cardiovascular disease. One of the major transcription factors that has been linked to both cardiovascular health and disease is NF-kappaB (nuclear factor kappaB). The NF-kappaB family controls multiple processes, including immunity, inflammation, cell survival, differentiation and proliferation, and regulates cellular responses to stress, hypoxia, stretch and ischaemia. It is therefore not surprising that NF-kappaB has been shown to influence numerous cardiovascular diseases including atherosclerosis, myocardial ischaemia/reperfusion injury, ischaemic preconditioning, vein graft disease, cardiac hypertrophy and heart failure. The function of NF-kappaB is largely dictated by the genes that it targets for transcription and varies according to stimulus and cell type. Thus NF-kappaB has divergent functions and can protect cardiovascular tissues from injury or contribute to pathogenesis depending on the cellular and physiological context. The present review will focus on recent studies on the function of NF-kappaB in the cardiovascular system.

Construction of NF-κB-targeting RNAi adenovirus vector and the effect of NF-κB pathway on proliferation and apoptosis of vascular endothelial cells

To construct a recombinant adenovirus vector expressing a RNAi for the Nuclear Factor kappa B (NF-κB)/p65 gene and use it to explore the role of the NF-κB pathway on the regulation of proliferation and apoptosis of vascular endothelial cells. A recombinant adenovirus containing a RNAi cassette targeting the p65 gene was constructed, and its silencing effect on p65 was detected by Western blot analysis in ECV304 cells. Expression of the p65 protein in ECV304 cells was efficiently down-regulated by the RNAi adenovirus for more than 6 days. ECV304 cells proliferation and apoptosis were measured using the MTT assay and flow cytometry, respectively. Blocking the NF-κB pathway with the RNAi adenovirus substantially decreased the proliferation of ECV304 cells, but only slightly affected cell apoptosis. We used a NF-κB/p65-targeting RNAi adenovirus to demonstrate the role of the NF-κB pathway in the regulation of ECV304 cell proliferation. This adenovirus may serve as an important tool to study the NF-κB pathway.

Interleukin-lβ induces migration of rat arterial smooth muscle cells through a mechanism involving increased matrix metalloproteinase-2 activity

BACKGROUND

Interleukin-lβ (IL-lβ) is associated with vascular smooth muscle cell (VSMC) migration during neointimal formation following arterial injury, of which matrix metalloproteinase-2 (MMP-2) may have an important role. We investigated whether IL-lβ stimulated migration and MMP-2 production in VSMC, and, if so, whether migration correlated with MMP-2 activity.

MATERIALS AND METHODS

Modified Boyden chamber assay quantified cultured rat aorta VSMC migration. Methyl-thiazolyl-tetrazolium assay assessed cell growth. Gelatin zymography and Western blotting determined MMP-2 activity and protein levels, respectively.

RESULTS

IL-lβ (0.1 - 10 ng/mL) induced migration of VSMC in a concentration-dependent manner without cell proliferation. VSMC released increasing levels of active MMP-2 in a dose-response fashion at IL-1β 1-10 ng/mL (P < 0.05) while significantly increased levels of latent MMP-2 (pro-MMP-2) were attained more gradually (10 ng/mL, P < 0.05). There was a dose-dependent increase in the ratio of active MMP-2 to pro-MMP-2 in response to IL-1β (1-10 ng/mL, P < 0.05), suggesting extracellular activation of pro-MMP-2. Protein levels on Western blot paralleled enzyme activity, with the synthesis of more active MMP-2 than pro-MMP-2 in response to IL-1β. IL-lβ-stimulated VSMC migration was significantly attenuated by both the pan-selective MMP inhibitor GM6001 and cis-9-octadecenoyl-N-hydroxylamide, a MMP-2-selective inhibitor.

CONCLUSIONS

IL-lβ increases MMP-2 activity in VSMC through increased protein synthesis and activation of pro-MMP-2. VSMC migration induced by IL-lβ requires active MMP-2. IL-lβ may play a role in arterial remodeling following injury.

Anti-inflammatory properties of C-Peptide

C-peptide, historically considered a biologically inactive peptide, has been shown to exert insulin-independent biological effects on a number of cells proving itself as a bioactive peptide with anti-inflammatory properties. Type 1 diabetic patients typically lack C-peptide, and are at increased risk of developing both micro- and macrovascular complications, which account for significant morbidity and mortality in this population. Inflammatory mechanisms play a pivotal role in vascular disease. Inflammation and hyperglycemia are major components in the development of vascular dysfunction in type 1 diabetes. The anti-inflammatory properties of C-peptide discovered to date are at the level of the vascular endothelium, and vascular smooth muscle cells exposed to a variety of insults. Additionally, C-peptide has shown anti-inflammatory properties in models of endotoxic shock and type 1 diabetes-associated encephalopathy. Given the anti-inflammatory properties of C-peptide, one may speculate dual hormone replacement therapy with both insulin and C-peptide in patients with type 1 diabetes may be warranted in the future to decrease morbidity and mortality in this population.

Ablation of NF-kappaB expression by small interference RNA prevents the dysfunction of human umbilical vein endothelial cells induced by high glucose

Diabetes is a major independent risk factor for cardiovascular disease and stroke. High glucose (HG) reduces endothelial cell (EC) proliferation with a concomitant increase in apoptosis. HG also induces the translocation of nuclear factor (NF)-kappaB in human umbilical vein endothelial cells (HUVECs). However, data regarding the relationship between NF-kappaB signaling and HG-induced endothelial dysfunction are limited. In the present study, we constructed an NF-kappaB-targeting RNA interference (RNAi) adenovirus vector and cultured HUVECs in 5.5, 20.5, or 30.5 mM D: -glucose or in daily alternating 5.5 or 30.5 mM D: -glucose. We assessed the effects of the NF-kappaB pathway on proliferation under HG conditions by measuring bromodeoxyuridine incorporation and conducting methyl thiazolyltetrazolium assays. We also tested apoptosis by performing flow cytometry and terminal deoxynucleotidyl transferase nick-end labeling assay. The RNAi adenovirus effectively downregulated expression of the p65 protein in HUVECs for more than 6 days. Blockage of the NF-kappaB pathway with the RNAi adenovirus substantially protected HUVECs from decreased proliferation and reduced cellular apoptosis in HG conditions. These findings may explain how hyperglycemia promotes dysfunction of ECs and could elucidate a potential new target for therapeutic interventions.

Antiapoptotic activities of bcl-2 correlate with vascular maturation and transcriptional modulation of human endothelial cells

Overexpression of a caspase-resistant form of Bcl-2 (D34A) in human umbilical vein endothelial cells (ECs) implanted into immunodeficient mice promotes the maturation of human EC-lined microvessels invested by vascular smooth muscle cells (VSMCs) of mouse origin. In contrast, EC implants not overexpressing Bcl-2 form only simple, uncoated EC tubes. Here the authors compare the phenotypes of vessels formed in vivo and the transcriptomes in vitro of EC expressing different forms of Bcl-2. Wild-type Bcl-2, like the caspase-resistant D34A Bcl-2 mutant, is antiapoptotic in vitro and promotes VSMC recruitment in vivo, whereas a G145E mutant that has diminished antiapoptotic activity in vitro does not promote vessel maturation in vivo. The D34A and wild-type forms of Bcl-2, but not the G145E mutant form of Bcl-2, significantly regulate RNA transcripts previously associated with EC-VSMC interactions and VSMC biology, including matrix Gla protein, insulin-like growth factor-binding protein (IGFBP)-2, matrix metalloproteinase (MMP)-14, ADAM17, stanniocalcin-1, and targets of the nuclear factor (NF)-kappa B, cAMP response element-binding (CREB), and activator protein 1 (AP1) transcription factor families. These effects of Bcl-2 on the transcriptome are detected in ECs cultured as angiogenic three-dimensional (3-D) tubes but are attenuated in ECs cultured as 2-D monolayers. Bcl-2-regulated transcription in ECs may contribute to vascular maturation, and support design of tissue engineering strategies using EC.

Increased protein O-GlcNAc modification inhibits inflammatory and neointimal responses to acute endoluminal arterial injury

Inflammation plays a major role in vascular disease. We have shown that leukocyte infiltration and inflammatory mediator expression contribute to vascular remodeling after endoluminal injury. This study tested whether increasing protein O-linked-N-acetylglucosamine (O-GlcNAc) levels with glucosamine (GlcN) and O-(2-acetamido-2-deoxy-d-glucopyranosylidene) amino-N-phenylcarbamate (PUGNAc) inhibits acute inflammatory and neointimal responses to endoluminal arterial injury. Ovariectomized rats were treated with a single injection of GlcN (0.3 mg/g ip), PUGNAc (7 nmol/g ip) or vehicle (V) 2 h before balloon injury of the right carotid artery. O-GlcNAc-modified protein levels decreased markedly in injured arteries of V-treated rats at 30 min, 2 h, and 24 h after injury but returned to control (contralateral uninjured) levels after 14 days. Both GlcN and PUGNAc increased O-GlcNAc-modified protein levels in injured arteries compared with V controls at 30 min postinjury; the GlcN-mediated increase persisted at 24 h but was not evident at 14 days. Proinflammatory mediator expression increased markedly after injury and was reduced significantly (30-50%) by GlcN and PUGNAc. GlcN and PUGNAc also inhibited infiltration of neutrophils and monocytes in injured arteries. Chronic (14 days) treatment with GlcN reduced neointima formation in injured arteries by 50% compared with V controls. Acute GlcN and PUGNAc treatment increases O-GlcNAc-modified protein levels and inhibits acute inflammatory responses in balloon-injured rat carotid arteries; 14 day GlcN treatment inhibits neointima formation in these vessels. Augmenting O-GlcNAc modification of proteins in the vasculature may represent a novel anti-inflammatory and vasoprotective mechanism.

Pyrrolidine dithiocarbamate restores endothelial cell membrane integrity and attenuates monocrotaline-induced pulmonary artery hypertension

Monocrotaline (MCT)-induced pulmonary artery hypertension (PAH) in rats is preceded by an inflammatory response, progressive endothelial cell membrane disruption, reduction in the expression of caveolin-1, and reciprocal activation of STAT3 (PY-STAT3). Superoxide and NF-kappaB have been implicated in PAH. To evaluate the role of caveolin-1, PY-STAT3 activation, and superoxide in PAH, MCT-injected rats were treated daily with pyrrolidine dithiocarbamate (PDTC; starting on days 1, 3, and 14 x 2 wk), an inhibitor of inflammation and NF-kappaB activation. Hemodynamic data, the expression of inhibitory (I)-kappaBalpha, caveolin-1, and Tie2 (a membrane protein), activation of PY-STAT3 and NF-kappaB, and superoxide chemiluminescence were examined. Rats developed progressive PAH at 2 wk post-MCT. There was progressive reduction in the expression of caveolin-1, Tie2, and activation of PY-STAT3 in the lungs. Reduction in I-kappaBalpha expression was present at 2 and 4 wk post-MCT. Superoxide chemiluminescence and NF-kappaB activation were observed only at 2 wk post-MCT and both decreased by 4 wk post-MCT despite progressive PAH. PDTC (starting on days 1 and 3) rescued caveolin-1 and Tie2, reversed MCT-induced PY-STAT3 activation, and attenuated PAH. In addition, PDTC restored I-kappaBalpha expression and reduced superoxide chemiluminescence at 2 wk but did not inhibit NF-kappaB activation despite attenuation of PAH. PDTC had no effect on established PAH. Increased superoxide chemiluminescence and NF-kappaB activation appear to be a transient phenomenon in the MCT model. Thus the disruption of endothelial cell membrane integrity resulting in caveolin-1 loss and reciprocal activation of PY-STAT3 plays a key role in the MCT-induced PAH.

Pyrrolidine dithiocarbamate restores endothelial cell membrane integrity and attenuates monocrotaline-induced pulmonary artery hypertension

Monocrotaline (MCT)-induced pulmonary artery hypertension (PAH) in rats is preceded by an inflammatory response, progressive endothelial cell membrane disruption, reduction in the expression of caveolin-1, and reciprocal activation of STAT3 (PY-STAT3). Superoxide and NF-kappaB have been implicated in PAH. To evaluate the role of caveolin-1, PY-STAT3 activation, and superoxide in PAH, MCT-injected rats were treated daily with pyrrolidine dithiocarbamate (PDTC; starting on days 1, 3, and 14 x 2 wk), an inhibitor of inflammation and NF-kappaB activation. Hemodynamic data, the expression of inhibitory (I)-kappaBalpha, caveolin-1, and Tie2 (a membrane protein), activation of PY-STAT3 and NF-kappaB, and superoxide chemiluminescence were examined. Rats developed progressive PAH at 2 wk post-MCT. There was progressive reduction in the expression of caveolin-1, Tie2, and activation of PY-STAT3 in the lungs. Reduction in I-kappaBalpha expression was present at 2 and 4 wk post-MCT. Superoxide chemiluminescence and NF-kappaB activation were observed only at 2 wk post-MCT and both decreased by 4 wk post-MCT despite progressive PAH. PDTC (starting on days 1 and 3) rescued caveolin-1 and Tie2, reversed MCT-induced PY-STAT3 activation, and attenuated PAH. In addition, PDTC restored I-kappaBalpha expression and reduced superoxide chemiluminescence at 2 wk but did not inhibit NF-kappaB activation despite attenuation of PAH. PDTC had no effect on established PAH. Increased superoxide chemiluminescence and NF-kappaB activation appear to be a transient phenomenon in the MCT model. Thus the disruption of endothelial cell membrane integrity resulting in caveolin-1 loss and reciprocal activation of PY-STAT3 plays a key role in the MCT-induced PAH.

Human proinsulin C-peptide reduces high glucose-induced proliferation and NF-kappaB activation in vascular smooth muscle cells

Excessive proliferation of vascular smooth muscle cells (VSMCs) is one of the primary lesions in atherosclerosis development during diabetes. High glucose triggers VSMC proliferation and initiates activation of the transcription factor nuclear factor (NF)-kappaB. Recently, clinical studies have demonstrated that replacement therapy with C-peptide, a cleavage product of insulin, to type 1 diabetic (T1D) patients is beneficial on a variety of diabetes-associated vascular complications. However, the mechanisms underlying the beneficial activity of C-peptide on the vasculature in conditions of hyperglycemia are largely unknown. The effects of C-peptide on the proliferation of human umbilical artery smooth muscle cell (UASMC) and aortic smooth muscle cell (AoSMC) lines cultured under high glucose for 48 h were tested. To gain insights on potential intracellular signaling pathways affected by C-peptide, we analyzed NF-kappaB activation in VSMCs since this pathway represents a key mechanism for the accelerated vascular disease observed in diabetes. High glucose conditions (25 mmol/L) stimulated NF-kappaB-dependent VSMC proliferation since the addition of two NF-kappaB-specific inhibitors, BAY11-7082 and PDTC, prevented proliferation. C-peptide at the physiological concentrations of 0.5 and 1 nmol/L decreased high glucose-induced proliferation of VSMCs that was accompanied by decreased phosphorylation of IkappaB and reduced NF-kappaB nuclear translocation. These results suggest that in conditions of hyperglycemia C-peptide reduces proliferation of VSMCs and NF-kappaB nuclear translocation. In patients with T1D, physiological C-peptide levels may exert beneficial effects on the vasculature that, under high glucose conditions, is subject to progressive dysfunction.

In vivo reduction of the nuclear factor-kappaB activity using synthetic cis-element decoy oligonucleotides suppresses intimal hyperplasia in the injured carotid arteries in rabbits

PURPOSE

Nuclear factor-kappaB (NF-kappaB) plays a critical role in inflammation-related reactions, and is also found in the injured arterial wall. The purpose of this study was to introduce synthetic double-stranded cis-element "decoy" oligonucleotides (ODNs) into the arterial wall using the hemagglutinating virus of Japan (HVJ) liposome, and to investigate the inhibitory potential of decoy ODN against balloon injury-induced intimal hyperplasia by reducing NF-kappaB activity.

METHODS

Fluorescein isothiocyanate (FITC)-labeled decoy ODNs using the HVJ-liposome method were tranfected in balloon-injured rabbit carotid arteries. We then performed electrophoretic mobility shift assay to examine NF-kappaB activity using balloon-injured arteries, and we introduced NF-kappaB decoy into balloon-injured arteries.

RESULTS

Transfection of FITC-labeled decoy ODNs by using the HVJ-liposome method demonstrated highly efficient protein expression with diffuse, frequent, and widespread nuclear signals over the entire medial layer, while the same amount of naked ODNs showed much less efficiency with scattered distribution of fluorescence in balloon-injured carotid arteries. Electrophoretic mobility shift assay showed activation of NF-kappaB in balloon-injured arteries. In vivo transfection of decoy ODNs mediated by HVJ liposome abolished the NF-kappaB activity in injured arteries with specific binding affinity to NF-kappaB protein. Intimal hyperplasia of carotid artery after balloon injury was reduced by approximately 50% by NF-kappaB decoy transfection compared with buffer treatment or scrambled decoy transfection.

CONCLUSION

Our results demonstrated involvement of NF-kappaB in intimal formation after arterial injury, and indicated that NF-kappaB can be an appropriate molecular target for anti-restenosis therapy.

A selective NFkappaB inhibitor, DHMEQ, reduced atherosclerosis in ApoE-deficient mice

BACKGROUND AND PURPOSE

Atherosclerosis is a chronic inflammatory process, and anti-inflammatory agents potentially inhibit the development of atherosclerosis. We tested whether a novel NFkappaB inhibitor reduces atherosclerosis.

METHODS

Dehydroxymethylepoxyquinomicin (10 mg/kg) or vehicle (chloromethyl cellulose) was injected intraperitoneally into apoE-deficient mice three times a week for 16 weeks. The entire aorta was excised and atherosclerotic area was determined at 4 and 16 weeks. Serum levels of cholesterol, triglyceride, TNF-alpha and adiponectin were also measured.

RESULTS

The atherosclerotic area was significantly smaller in mice treated with dehydroxymethyl-epoxyquinomicin both at 4 and 16 weeks. There was no significant difference in body weight or serum levels of cholesterol, triglyceride, and adiponectin.

CONCLUSIONS

A new NFkappaB inhibitor, dehydroxymethylepoxyquinomicin, reduced atherosclerosis without affecting plasma lipid levels in apoE-deficient mice.

Molecular and signaling mechanisms of atherosclerosis in insulin resistance

Although the prevalence of cardiovascular complications is increased in insulin-resistant individuals, the underlying causes of this link have been elusive. Recent work suggests that several intracellular signal transduction pathways are inappropriately activated by hyperinsulinemia, hyperglycemia, increased free fatty acids, dyslipidemia, various inflammatory cytokines and adipokines--factors that are increased in insulin resistance. Once activated, substantial cross talk occurs between these pathways, especially a self-reinforcing cascade of vascular inflammation and cell dysfunction, greatly increasing the risk and severity of atherosclerosis in the insulin-resistant individual. We review several key cell-signalling pathways, describe how they are activated in they insulin-resistant state and the damage they induce, and discusses possible therapeutic approaches to limit vascular damage.

Carbon monoxide protects hepatocytes from TNF-alpha/Actinomycin D by inhibition of the caspase-8-mediated apoptotic pathway

We have previously shown that carbon monoxide (CO) (250 ppm) prevented tumor necrosis factor-alpha (TNFalpha)-induced apoptosis and activated the transcription factor NF-kappaB in hepatocytes both in vivo and in vitro. These studies were conducted to further determine the mechanisms by which CO suppresses apoptotic signaling in TNFalpha (10 ng/ml) and Actinomycin D (ActD, 200 ng/ml)-treated hepatocytes. Consistent with our previous findings, CO protected against TNFalpha/ActD-induced cell death, which is in part dependent on NF-kappaB activation. This was associated with a reduction in mitochondrial damage, a decrease in cytochrome c release, and an inhibition of translocation of Bcl proteins to mitochondria. In conjugation with inhibition of these mitochondrial events, CO also suppressed caspases-8 and -3 cleavage in response to TNFalpha/ActD. Inhibition of NF-kappaB activation resulted in diminished CO-induced cFLIP expression and increased caspase-8 cleavage from cells treated with TNFalpha/ActD. These data indicate that CO interferes with apoptotic signaling at a proximal step.

Regulation of proliferation and gene expression in cultured human aortic smooth muscle cells by resveratrol and standardized grape extracts

Epidemiologic studies suggest that low to moderate consumption of red wine is inversely associated with the risk of coronary heart disease; the protection is in part attributed to grape-derived polyphenols, notably trans-resveratrol, present in red wine. It is not clear whether the cardioprotective effects of resveratrol can be reproduced by standardized grape extracts (SGE). In the present studies, we determined, using cultured human aortic smooth muscle cells (HASMC), growth and specific gene responses to resveratrol and SGE provided by the California Table Grape Commission. Suppression of HASMC proliferation by resveratrol was accompanied by a dose-dependent increase in the expression of tumor suppressor gene p53 and heat shock protein HSP27. Using resveratrol affinity chromatography and biochemical fractionation procedures, we showed by immunoblot analysis that treatment of HASMC with resveratrol increased the expression of quinone reductase I and II, and also altered their subcellular distribution. Growth of HASMC was significantly inhibited by 70% ethanolic SGE; however, gene expression patterns in various cellular compartments elicited in response to SGE were substantially different from those observed in resveratrol-treated cells. Further, SGE also differed from resveratrol in not being able to induce relaxation of rat carotid arterial rings. These results indicate that distinct mechanisms are involved in the regulation of HASMC growth and gene expression by SGE and resveratrol.

Parthenolide modulates the NF-kappaB-mediated inflammatory responses in experimental atherosclerosis

OBJECTIVE

Activation of transcription factor NF-kappaB is an important step in the development of vascular damage, because it controls inducible genes, including many inflammatory mediators. The pharmacological modulation of this process is the main objective in the design of new therapies for atherosclerosis. In this work we analyzed the effects of the natural compound parthenolide (PTN), an NF-kappaB inhibitor.

METHODS AND RESULTS

In vascular smooth muscle cells (VSMCs) and monocytes stimulated with lipopolysaccharide (LPS), nontoxic doses of PTN reduced IkappaBalpha degradation, NF-kappaB activation, and MCP-1 expression, without inhibiting AP-1 and MAPK. In apoE mice, treatment with low (2 mg/kg, 20 weeks), medium (4 mg/kg, 10 weeks), and high (10 mg/kg, 10 weeks) dose of PTN reduced the size of aortic lesion, decreased macrophage, and increased VSMC content in the lesions. Treated mice showed reduced serum levels of MCP-1 and attenuated NF-kappaB activity, but not AP-1, in the lesions. Moreover, PTN affects neither apoptotic cell death nor oxidative stress in cultured cells and mice.

CONCLUSIONS

NF-kappaB inhibition by PTN retards atherosclerotic lesions in apoE mice, by reducing lesion size and changing plaque composition. This natural compound could represent a novel therapeutic approach to inflammation during vascular damage.

Resveratrol at high doses acts as an apoptotic inducer in endothelial cells

PURPOSES

Resveratrol is a phenolic compound found in grapes and other food products. In order to assess the availability of resveratrol as an angio-inhibiting drug, we examined whether resveratrol plays an important role in bovine aortic endothelial cells (BAECs) for cell apoptosis and cell migration.

METHODS AND MATERIALS

Endothelial cell apoptosis was observed as detected by the Hoechst staining and the caspase-3 activity. Additionally, Western blotting was performed for monitoring the activities of various cell signaling molecules.

RESULTS

Resveratrol was shown to act as a pro-apoptotic agent. The pro-apoptotic effect of resveratrol was as great as that of etoposide, a well-known anti-cancer drug. In addition, resveratrol had an inhibitory effect on endothelial cell migration. The demonstrated efficacy of resveratrol suggests that resveratrol may be utilized as an anti-angiogenic drug. To determine the underlying mechanisms, we further investigated which signaling molecules are activated by resveratrol. Extracellular signal-regulated kinase (ERK) was activated by the treatment with resveratrol in BAECs, whereas endothelial nitric oxide synthetase (eNOS), Akt, and Jun N-terminal kinase (JNK) were inhibited. The pretreatment with PD compound, an ERK inhibitor, had no effect on the pro-apoptosis induced by resveratrol.

CONCLUSION

Resveratrol plays an important role in endothelial cell apoptosis, indicating that resveratrol can be utilized as a potent anti-angiogenic drug.

IKKbeta-dependent NF-kappaB pathway controls vascular inflammation and intimal hyperplasia

Nuclear factor-kappaB (NF-kappaB)-mediated vascular inflammation is a prominent characteristic of atherogenesis and restenosis. We noted that angioplastic injury to carotid artery elicited two phases of NF-kappaB activation characterized by an early activation in the arterial media and a late activation coupled with high levels of inhibitor of IkappaB kinase (IKK) activity in intima. These findings prompted us to elucidate the role for the different phases of NF-kappaB activation and IKK in the progress of vascular repair. Our results show that blockade of the early NF-kappaB activation by perivascular administration of pyrrolidine dithiocarbamate transiently attenuates the expression of proinflammatory genes in the injured vessels but does not affect intimal formation. Interruption of IKKbeta by overexpressing a dominant-negative IKKbeta in the injured artery effectively inhibited the late phase of NF-kappaB activation, resulting in down-regulation of inducible nitric oxide synthase, tumor necrosis factor alpha, and monocyte chemoattractant protein-1 expression in conjunction with a 36% reduction in intima size, albeit with a lack of inhibitory effect on the early NF-kappaB activation. Collectively, these findings show that the IKKbeta-mediated late-phase NF-kappaB activation contributes to intimal hyperplasia and the accompanied vascular inflammatory responses.

Inhibition of geranylgeranyltransferase I decreases generation of vascular reactive oxygen species and increases vascular nitric oxide production

BACKGROUND

Vascular injury with endothelial dysfunction results in an imbalance between the production of vasoprotective molecules such as nitric oxide (NO) and deleterious reactive oxygen species (ROS). The purpose of this work was to test the hypothesis that inhibition of geranylgeranyltransferase I (GG Tase I) reduces vascular injury by increasing vascular NO production while decreasing ROS generation.

METHODS AND RESULTS

GGTI-298 decreased the formation of intimal hyperplasia at 14 days following balloon injury. GGTI-298 (10 microm) inhibited activation of RhoA and Rac1 as well as inhibited SMC proliferation. GGTI increased SMC-inducible NO synthase (iNOS) levels and NO production in vitro. Additionally, the activation of NAD(P)H oxidase subunits was decreased by GGTI in vitro. This correlated with a decrease in TNF-alpha- or angiotensin-II-induced ROS production assayed by DCF fluorescence. In vivo, GGTI treatment increased endothelial NOS (eNOS) expression in uninjured arteries and iNOS expression in balloon-injured arteries. Furthermore, GGTI treatment attenuated balloon-injury-induced superoxide generation assayed by MCLA luminescence.

CONCLUSIONS

GGTI decreases the production of ROS and increases the production of NO both in vitro and in vivo. These effects may be mediated via the inhibition of activation of the small GTPases Rac1 and RhoA. Pharmacological inhibition of GGTase I may prove to be a useful clinical adjunct in the treatment of cardiovascular diseases.

Nuclear factor kappaB signaling in atherogenesis

Atherosclerosis is an inflammatory disease, characterized by the accumulation of macrophage-derived foam cells in the vessel wall and accompanied by the production of a wide range of chemokines, cytokines, and growth factors. These factors regulate the turnover and differentiation of immigrating and resident cells, eventually influencing plaque development. One of the key regulators of inflammation is the transcription factor nuclear factor kappaB (NF-kappaB), which, for a long time, has been regarded as a proatherogenic factor, mainly because of its regulation of many of the proinflammatory genes linked to atherosclerosis. NF-kappaB may play an important role in guarding the delicate balance of the atherosclerotic process as a direct regulator of proinflammatory and anti-inflammatory genes and as a regulator of cell survival and proliferation. Here we address recent literature on the function of NF-kappaB in inflammatory responses and its relation to atherosclerosis.

Rapamycin suppresses experimental aortic aneurysm growth

OBJECTIVE

Inflammatory modulators are important in the pathogenesis of aneurysmal disease. Gene expression profiling of experimental abdominal aortic aneurysm (AAA) tissue demonstrated upregulation of the FK506BP12 (rapamycin binding protein) gene product. Rapamycin is a potent immunosuppressor that prevents recurrent stenosis. However, its effect on aneurysm formation has not been studied. We therefore examined the effect of rapamycin in an experimental rat AAA model.

METHODS

Adult male Wistar rats underwent elastase infusion into isolated infrarenal aortas to create experimental aneurysms. Rats were randomized to receive either rapamycin or placebo via gastric lavage daily starting on the day of surgery. On postoperative day 7 the aneurysm was measured, the infrarenal aorta was harvested, and the rats were euthanized. NF kappa B was measured with Western blotting as a marker of inflammation. Matrix metalloproteinase (MMP)-9 protein levels were measured. Hematoxylin-eosin and elastin staining were used to examine tissue inflammation and elastin preservation.

RESULTS

Aneurysms were significantly smaller in diameter in the rapamycin-treated group (3.3 +/- 0.7 mm vs 4.5 +/- 0.5 mm; P <.0001). NF kappa B levels were significantly reduced by 64% +/- 14% in rapamycin-treated aortas (P =.023). MMP-9 was reduced in rapamycin-treated aortas by 54% +/- 22% (P =.043). Hematoxylin-eosin and elastin staining showed no changes in inflammatory infiltrate or degradation of elastin fibers in elastase-infused aortic segments in rapamycin-treated rats.

CONCLUSION

Rapamycin significantly reduces the rate of aneurysm expansion in the experimental AAA rat model by 40%. Biochemical evidence suggests that this is related to suppression of inflammatory signaling and decreased MMP-9 levels. Rapamycin could provide a new treatment for small aneurysms.

CLINICAL RELEVANCE

Human aortic aneurysms are characterized histologically by an inflammatory infiltrate with severe proteolytic destruction. Rapamycin is an immunosuppressive agent commonly used to control transplant rejection and intimal hyperplasia by modulating the inflammatory cascade. In this experimental model rapamycin suppressed aneurysm expansion, decreased NF kappa B activation (a marker of inflammation), and decreased matrix metalloproteinase-9 levels. It is hoped that rapamycin or other similar anti-inflammatory drugs will one day be able to control aneurysm expansion in patients

Daio-Orengedokudo works as a cell-proliferating compound in endothelial cells

Daio-Orengedokuto is a combination drug that has inhibitory effects on HMG-CoA reductase and pancreatic lipase. Here we investigated whether Daio-Orengedokuto has effects on vascular endothelial cells. To determine its effects on blood vessels, we examined roles of Daio-Orengedokuto in cell migration, cell apoptosis and cell cycle progression over bovine aortic endothelial cells (BAECs). Interestingly, Daio-Orengedokuto was shown to work as an anti-apoptotic agent, a cell cycle progressive agent and a cell-migration inducing agent in BAECs, whereas it was known to act as a tumor suppressor in cancer cells (unpublished data). The inducing effect of Daio-Orengedokuto on cell-cycle progression and cell migration in endothelium suggests that Daio-Orengedokuto may be referred to as a drug, inducing angiogenesis, healing wounds, and (or) remodeling vascular tissue. Then we further investigated which signaling molecules were activated by Daio-Orengedokuto and found that extracellular signal-regulated kinase (ERK) phosphorylation and IκB degradation were stimulated by the Daio-Orengedokuto treatment in BAECs. More interestingly, pretreatment with PD compound, an ERK inhibitor, blocked the anti-apoptosis induced by Daio-Orengedokuto. In conclusion, Daio-Orengedokuto plays a role in endothelial cell proliferation via activation of MAP kinase.Key words: Daio-Orengedokuto, endothelial cells, proliferation, anti-apoptosis, cell signaling.

Canonical pathway of nuclear factor kappa B activation selectively regulates proinflammatory and prothrombotic responses in human atherosclerosis

Nuclear factor kappa B (NF-kappa B) activation has been observed in human atherosclerotic plaques and is enhanced in unstable coronary plaques, but whether such activation has a protective or pathophysiological role remains to be determined. We addressed this question by developing a short-term culture system of cells isolated from human atherosclerotic tissue, allowing efficient gene transfer to directly investigate signaling pathways in human atherosclerosis. We found that NF-kappa B is activated in these cells and that this activity involves p65, p50, and c-Rel but not p52 or RelB. This NF-kappa B activation can be blocked by overexpression of I kappa B alpha or dominant-negative I kappa B kinase (IKK)-2 but not dominant-negative IKK-1 or NF-kappa B-inducing kinase, resulting in selective inhibition of inflammatory cytokines (tumor necrosis factor alpha, IL-6, and IL-8), tissue factor, and matrix metalloproteinases without affecting the antiinflammatory cytokine IL-10 or tissue inhibitor of matrix metalloproteinases. Our results demonstrate that the canonical pathway of NF-kappa B activation that involves p65, p50, c-Rel, and IKK-2 is activated in human atherosclerosis and results in selective up-regulation of major proinflammatory and prothrombotic mediators of the disease.