Nuclear factor-kappaB activity and arterial response to balloon injury

Transcriptomic profiling of experimental arterial injury reveals new mechanisms and temporal dynamics in vascular healing response

Objective

Endovascular interventions cause arterial injury and induce a healing response to restore vessel wall homeostasis. Complications of defective or excessive healing are common and result in increased morbidity and repeated interventions. Experimental models of intimal hyperplasia are vital for understanding the vascular healing mechanisms and resolving the clinical problems of restenosis, vein graft stenosis, and dialysis access failure. Our aim was to systematically investigate the transcriptional, histologic, and systemic reaction to vascular injury during a prolonged time.

Methods

Balloon injury of the left common carotid artery was performed in male rats. Animals (n = 69) were euthanized before or after injury, either directly or after 2 hours, 20 hours, 2 days, 5 days, 2 weeks, 6 weeks, and 12 weeks. Both injured and contralateral arteries were subjected to microarray profiling, followed by bioinformatic exploration, histologic characterization of the biopsy specimens, and plasma lipid analyses.

Results

Immune activation and coagulation were key mechanisms in the early response, followed by cytokine release, tissue remodeling, and smooth muscle cell modulation several days after injury, with reacquisition of contractile features in later phases. Novel pathways related to clonal expansion, inflammatory transformation, and chondro-osteogenic differentiation were identified and immunolocalized to neointimal smooth muscle cells. Analysis of uninjured arteries revealed a systemic component of the reaction after local injury, underlined by altered endothelial signaling, changes in overall tissue bioenergy metabolism, and plasma high-density lipoprotein levels.

Conclusions

We demonstrate that vascular injury induces dynamic transcriptional landscape and metabolic changes identifiable as early, intermediate, and late response phases, reaching homeostasis after several weeks. This study provides a temporal “roadmap” of vascular healing as a publicly available resource for the research community.

Endovascular intervention causes an injury to the arterial wall that subsequently induces a healing response to restore the vessel wall homeostasis. Complications after vascular interventions related to defective or excessive healing response, such as thrombosis or restenosis, are common and result in increased morbidity, suffering of the patient, need for repeated interventions, and possibly death. Thus, there is a need for better understanding of the underlying molecular mechanisms during vascular injury and healing response to identify and to assess the risk of complications in patients. Using an experimental model of vascular injury, this study demonstrates the full landscape of dynamic transcriptional changes in the resolution of vascular injury, accompanied also by systemic variations in plasma lipid levels and reaching homeostasis several weeks after injury. These results can guide the development of new strategies and molecular targets for modulation of the intimal response on endovascular interventions.

Nuclear Factor-κB is Activated in Filter-Implanted Vena Cava

BACKGROUND

Implantation of a retrievable vena cava filter (VCF) is an effective method for preventing pulmonary embolism. Retrieval of filters, however, may be difficult due to intimal hyperplasia and inflammation in the cava wall. The transcription factor nuclear factor-kappaB (NF-κB) plays an important role in regulation of numerous genes participating in the inflammatory and proliferative responses of cells. The present study was to determine whether VCF implantation resulted in activation of NF-κB in the venous neointima.

METHODS

Filters were placed in vena cava (VC) in four swine for 30 days and then removed. Intimal specimens adhering to the filter struts were analyzed with reference to normal VC tissues. Immunohistochemical analyses were used to assess the NF-κB subunits p65 and p50 and the phosphorylated inhibitor of κB-α (phosphor-IκB-α) in the tissues. NF-κB DNA-binding activity was measured with enzyme-linked immunosorbent assay.

RESULTS

As compared to normal VC tissues, the intimal tissues contained higher percentages of cell nucleus-located p65 and p50, and NF-κB DNA-binding activity. Elevated immunoreactivities of p65, p50 and phosphor-IκB-α were also present in the intima.

CONCLUSION

The present study demonstrates for the first time that VCF implantation caused NF-κB activation in neointima. We further demonstrate the activation is at least partly due to phosphorylation of IκB-α. Our data suggest that NF-κB activation would significantly contribute to development of intimal hyperplasia and inflammation in filter-inserted vena cava walls. NF-κB might be a therapeutic target for inhibiting filter-induced neointima and improving filter retrieval.

Vascular smooth muscle cell proliferation as a therapeutic target. Part 1: molecular targets and pathways

Cardiovascular diseases are a major cause of human death worldwide. Excessive proliferation of vascular smooth muscle cells contributes to the etiology of such diseases, including atherosclerosis, restenosis, and pulmonary hypertension. The control of vascular cell proliferation is complex and encompasses interactions of many regulatory molecules and signaling pathways. Herein, we recapitulated the importance of signaling cascades relevant for the regulation of vascular cell proliferation. Detailed understanding of the mechanism underlying this process is essential for the identification of new lead compounds (e.g., natural products) for vascular therapies.

SGK1 up-regulates Orai1 expression and VSMC migration during neointima formation after arterial injury

Supplementary Material to this article is available online at www.thrombosis-online.com

TW-01, a piperazinedione-derived compound, inhibits Ras-mediated cell proliferation and angioplasty-induced vascular restenosis

PURPOSE

Vascular smooth muscle cell (VSMC) proliferation plays a critical role in the pathogenesis of atherosclerosis and restenosis. This study investigated piperazinedione derived compound TW-01-mediated inhibitory effects on VSMC proliferation and intimal hyperplasia.

METHODS

Cell proliferation was determined using [(3)H]-thymidine incorporation and MTT assay; cell cycle distribution was measured using flow cytometry; proteins and mRNA expression were determined using western blotting and RT-PCR analyses; DNA binding activity of nuclear factor-κB (NF-κB), as measured using enzyme-linked immunosorbent assays (ELISA); in vivo effects of TW-01 were determined using balloon angioplasty in the rat.

RESULTS

TW-01 significantly inhibited cell proliferation. At the concentrations used, no cytotoxic effects were observed. Three predominant signaling pathways were inhibited by TW-01: (a) extracellular signal-regulated kinase (ERK)1/2 mitogen-activated protein kinase (MAPK) activation and its downstream effectors of c-fos, c-jun, and c-myc; (b) DNA binding activity of nuclear factor-κB (NF-κB); and, (c) Akt/protein kinase B (PKB) and cell cycle progression. Furthermore, TW-01 also inhibited Ras activation, a shared upstream event of each of these signaling cascades. In vascular injury studies, oral administration of TW-01 significantly suppressed intimal hyperplasia induced by balloon angioplasty.

CONCLUSION

The present study suggests that TW-01 might be a potential candidate for atherosclerosis treatment.

Vascular smooth muscle cell in atherosclerosis

Vascular smooth muscle cells (VSMCs) exhibit phenotypic and functional plasticity in order to respond to vascular injury. In case of the vessel damage, VSMCs are able to switch from the quiescent 'contractile' phenotype to the 'proinflammatory' phenotype. This change is accompanied by decrease in expression of smooth muscle (SM)-specific markers responsible for SM contraction and production of proinflammatory mediators that modulate induction of proliferation and chemotaxis. Indeed, activated VSMCs could efficiently proliferate and migrate contributing to the vascular wall repair. However, in chronic inflammation that occurs in atherosclerosis, arterial VSMCs become aberrantly regulated and this leads to increased VSMC dedifferentiation and extracellular matrix formation in plaque areas. Proatherosclerotic switch in VSMC phenotype is a complex and multistep mechanism that may be induced by a variety of proinflammatory stimuli and hemodynamic alterations. Disturbances in hemodynamic forces could initiate the proinflammatory switch in VSMC phenotype even in pre-clinical stages of atherosclerosis. Proinflammatory signals play a crucial role in further dedifferentiation of VSMCs in affected vessels and propagation of pathological vascular remodelling.

Perivascular delivery of neomycin inhibits the activation of NF-κB and MAPK pathways, and prevents neointimal hyperplasia and stenosis after arterial injury

The nuclear transcription factor kappaB (NF-kappaB) is a cytoplasmic dimer that, as the family of mitogen-activated protein kinase (MAPK), can directly regulate the expression of early genes and genes involved in the stress response, following a variety of physiological or pathological stimuli. Both of them stimulate the transcription of many proteins, which are considered important during inflammation. A crucial role has been assigned to these factors in cellular proliferation and in neointimal hyperplasia secondary to the endothelial lesion of arterial vessels. On the other hand, it has been described that neomycin can have an inhibitory function on tumor cell proliferation, through the inhibition of different intracellular pathways of signaling, among them the NF-kappaB and MAPK pathways. Rat common carotid artery was subjected to balloon angioplasty. Neomycin sulfate (18 mg) was applied using pluronic acid gel on the adventitial surface of the injured vessel. MAPK and NF-kappaB activation was quantified after 24 hours with immunohistochemical staining. Neointimal formation was quantified after 14 days with morphometry. Immunohistochemistry results demonstrating MAPK and NF-kappaB activation reveal that both transcription factors are activated in the media of the control vessel wall. In contrast, the immunoreactivity for MAPK and NF-kappaB in the sections obtained from arteries treated with neomycin over 24 hours was insufficient or nonexistent. Treatment with neomycin on adventitia over 14 days in arteries on which angioplasty was performed shows a neointimal index (intimal area/medial area) decrease of 71% in comparison with arteries that were not treated. The adventitial neomycin treatment over 14 days produces a very significant increase (287.5%; p<0.0001) in the arterial luminal circumference in comparison with arteries treated with vehicle. These results support the theory that neomycin plays an important role against neointimal hyperplasia through the inhibition of MAPK and NF-kappaB activation.

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.

Mobilization of regulatory T cells in response to carotid injury does not influence subsequent neointima formation

AIM

T cells have been attributed an important role in modulating repair responses following vascular injury. The aim of this study was to investigate the role of different T cell subsets in this context.

METHODS AND RESULTS

A non-obstructive collar was introduced to inflict carotid artery injury in mice and subsequent activation of immune cells in draining lymph nodes and spleen were studied by flow cytometry. Carotid artery injury of wild type mice was associated with mobilization of both Th1 type CD4(+)IFNγ(+) and regulatory CD4(+)CD25(+)FoxP3(+) T cells in draining lymph nodes. Studies using FoxP3-green fluorescent protein (GFP) transgenic C57/Bl6 mice demonstrated scattered presence of regulatory T cells in the adventitial tissue of injured arteries as well as a massive emigration of regulatory T cells from the spleen in response to carotid injury. However, deletion of antigen presentation to CD4+ T cells (H2(0) mice), as well as deletion of regulatory T cells (through treatment with blocking anti-CD25 antibodies), did not affect neointima formation. Also deletion of antigen presentation to CD8(+) T cells (Tap1(0) mice) was without effect on carotid collar-induced neointima formation.

CONCLUSION

The results demonstrate that carotid artery injury is associated with mobilization of regulatory T cells. Depletion of regulatory T cells does not, however, influence the subsequent repair processes leading to the formation of a neointima. The results also demonstrate that lack of CD8(+) T cells does not influence neointima formation in presence of functional CD4(+) T cells and B cells.

Active site-inactivated factor VIIa inhibits nuclear factor kappa B activation in intestinal ischemia and reperfusion

BACKGROUND

Intestinal ischemia and reperfusion (I/R) injury is a pivotal mechanism in critical illness and in the development of multiple organ dysfunction syndrome, in which the nuclear factor kappa B (NF-κB) activation plays a central role. Intestinal I/R injury initiates the extrinsic tissue factor or factor VIIa-dependent pathway of coagulation, also of importance in multiple organ dysfunction syndrome. Our aim was to analyze NF-κB activation in I/R injury in the rat intestine and in two main "shock" organs, that is, the liver and lungs. Pretreatment with active site-inactivated factor VII (FVIIai), an inhibitor of the extrinsic pathway, was evaluated.

MATERIALS AND METHODS

NF-κB activation was analyzed using enzyme-linked immunosorbent assay (ELISA) and electrophoretic mobility shift assay (EMSA) studies of nuclear extracts from the intestine, liver, and lungs in rats subjected to intestinal I/R injury. FVIIai was given 90 min before the induction of intestinal ischemia.

RESULTS

I/R induced NF-κB p65 activation in all three organs, especially in the liver. Pretreatment with FVIIai counteracted NF-κB activation in all three tissues studied. A commercially available ELISA for (human) NF-κB p65 and EMSA gave parallel results.

CONCLUSIONS

I/R injury in the rat intestine induces a pronounced activation of NF-κB p50 or p65 in the small intestine and in the liver and lungs. The NF-κB activation is especially pronounced in the liver and plays a central role in the regulation of transcription of cytokines, adhesion molecules, and chemokines. ELISA for (human) NF-κB p65 and "gold standard" EMSA gave parallel results. Pretreatment with FVIIai completely counteracted NF-κB activation in the intestine and liver, although not in the lungs.

CD40 is essential in the upregulation of TRAF proteins and NF-kappaB-dependent proinflammatory gene expression after arterial injury

Despite extensive investigations, restenosis, which is characterized primarily by neointima formation, remains an unsolved clinical problem after vascular interventions. A recent study has shown that CD40 signaling through TNF receptor associated factor 6 (TRAF6) plays a key role in neointima formation after carotid artery injury; however, underlying mechanisms are not clearly elucidated. Because neointima formation may vary significantly depending on the type of injury, we first assessed the effect of CD40 deficiency on neointima formation in 2 injury models, carotid artery ligation and femoral artery denudation injury. Compared with wild-type mice, CD40 deficiency significantly reduced neointima formation and lumen stenosis in two different models. Further, we investigated the mechanism by which CD40 signaling affects neointima formation after arterial injury. In wild-type mice, the expression levels of CD40, several TRAF proteins, including TRAF1, TRAF2, TRAF3, TRAF5, and TRAF6, as well as total NF-kB p65 and phospho-NF-kB p65, in the carotid artery were markedly upregulated within 3-7 days after carotid ligation. Deficiency of CD40 abolished the injury-induced upregulation of TRAFs including TRAF6 and NF-kB-p65 in the injured vessel wall. Further, CD40(-/-) mice showed a significant decrease in the recruitment of neutrophils (at 3, 7d) and macrophages (at 7, 21d) into injured artery; this effect was most likely attributed to inhibition of NF-kB activation and marked downregulation of NF-kB-related gene expression, including cytokines (TNFα, IL-1β, IL-6), chemokines (MCP-1), and adhesion molecules (ICAM-1, VCAM-1). Moreover, neutrophil recruitment in a model of thioglycollate-induced peritonitis is impaired in CD40-deficient mice. In vitro data revealed that CD40 deficiency blocked CD40L-induced NF-kB p65 nuclear translocation in leukocytes. Altogether, our data identified for the first time that CD40 is essential in the upregulation of TRAF6, NF-kB activation, and NF-kB-dependent proinflammatory genes in vivo. Our findings firmly established the role for CD40 in neointima formation in 2 distinct injury models.

Divergent roles of NF-κB and Egr-1 in flow-dependent restenosis after angioplasty and stenting

OBJECTIVE

Restenosis after both angioplasty and stenting is flow dependent. The effects of flow are preventable with the antioxidant pyrrolidine dithiocarbamate (PDTC) after angioplasty but not after stenting. We examined to what extent these observations could be explained by the effect of PDTC on NF-κB and Egr-1, two transcription factors which are both flow- and redox-sensitive.

METHODS

In a flow-modified rabbit carotid model of angioplasty and stenting, we assessed the effects of altered flow, injury and PDTC on expression of Egr-1 and nuclear binding activity of NF-κB. We also examined the effects of local delivery of decoy oligodeoxynucleotides (ODN) specific for NF-κB and Egr-1 on morphology at 28 days in normal and low flow.

RESULTS

The activity of both transcription factors was enhanced by injury (stent>balloon alone) and was further augmented by low flow. PDTC markedly attenuated the activity of NF-κB but not Egr-1. Specific decoy ODN for Egr-1 attenuated intima formation in both stented and balloon injured vessels in both normal and low flow but had no effect on remodelling. In contrast while NF-κB decoy ODN caused a modest but significant reduction in intima formation, there was a striking effect on remodelling in low flow vessels only.

CONCLUSIONS

We conclude that Egr-1 plays a pivotal role in intima formation under all flow conditions and that NF-κB plays a key role in flow-sensitive remodelling after angioplasty and that NF-κB inhibition likely accounts for a significant part of the morphological effects of PDTC after vessel injury.

Paracrine osteogenic signals via bone morphogenetic protein-2 accelerate the atherosclerotic intimal calcification in vivo

OBJECTIVE

Vascular calcification is an important risk factor for cardiovascular diseases. Here, we investigated a role of dedifferentiated vascular smooth muscle cells (VSMCs) in the atherosclerotic intimal calcification.

METHODS AND RESULTS

We prepared human cultured VSMCs in either redifferentiatiated or dedifferentiated state and analyzed the gene expressions of bone-calcification regulatory factors. Expression of bone morphogenetic protein-2 (BMP-2), a potent initiator for osteoblast differentiation, was significantly enhanced in dedifferentiated VSMCs. Furthermore, endogenous BMP-2 antagonists, such as noggin, chordin, and matrix gamma-carboxyglutamic acid protein, were all downregulated in the dedifferentiated VSMCs. Conditioned medium from dedifferentiated VSMCs, but not from redifferentiated VSMCs, stimulated the osteoblastic differentiation of the mesenchymal progenitor C2C12 cells, which was abolished by BMP-2 knockdown. In atherosclerotic intima from apolipoprotein (apo)E-deficient mice, αSM-actin-positive cells, presumably dedifferentiated VSMCs, expressed BMP-2. We generated BMP-2-transgenic mice using αSM-actin promoter and crossed them with apoE-deficient mice (BMP-2-transgenic/apoE-knockout). Significantly accelerated atherosclerotic intimal calcification was detected in BMP-2-transgenic/apoE-knockout mice, although serum lipid concentration and atherosclerotic plaque size were not different from those in apoE-knockout mice. Enhanced calcification appeared to be associated with the frequent emergence of osteoblast-like cells in atherosclerotic intima in BMP-2-transgenic/apoE-knockout mice.

CONCLUSIONS

Our findings collectively demonstrate an important role of dedifferentiated VSMCs in the pathophysiology of atherosclerotic calcification through activating paracrine BMP-2 osteogenic signals.

Smoking and atherosclerotic cardiovascular disease: Part I: atherosclerotic disease process

The normal endothelium inhibits platelet and leukocyte adhesion to the vascular surface maintaining a balance of profibrinolytic and prothrombotic activity. Endothelial function is assessed largely as endothelium-dependent vasomotion, partly based on the assumption that impaired endothelium-dependent vasodilation reflects the alteration of important endothelial functions. Atherosclerotic risk factors, such as hypercholesterolemia, hypertension, diabetes and smoking, are associated with endothelial dysfunction. In the diseased endothelium, the balance between pro- and antithrombotic, pro- and anti-inflammatory, pro- and antiadhesive or pro- and antioxidant effects shifts towards a proinflammatory, prothrombotic, pro-oxidative and proadhesive phenotype of the endothelium. A common mechanism underlying endothelial dysfunction is related to the increased vascular production of reactive oxygen species. Recent studies suggest that inflammation per se, and C-reactive protein in particular, may contribute directly to endothelial dysfunction. The loss of endothelial integrity is a hallmark of atherosclerosis and the causal possible link between each individual risk factor, the development of atherosclerosis and the subsequent clinical events, such as myocardial infarction or stroke.

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.

Human plasminogen kringle 1-5 reduces atherosclerosis and neointima formation in mice by suppressing the inflammatory signaling pathway

BACKGROUND

Activation of vascular endothelial cells plays an important role in atherogenesis and plaque instability. Recent research has demonstrated that late-stage inhibition of plaque angiogenesis by angiostatin (kringle 1-4) reduces macrophage accumulation and slows the progression of advanced atherosclerosis. Kringle 1-5 (K(1-5)) is a variant of angiostatin that contains the first five kringle domains of plasminogen.

OBJECTIVE

To investigate whether K(1-5) has an inhibitory effect on early-stage atherosclerosis, using the apolipoprotein E (ApoE)-deficient mouse model and a carotid artery ligation model.

METHODS

ApoE-deficient mice received K(1-5) treatment for 4 weeks, and the severity of aortic atherosclerosis was measured. In the ligation model, the left common carotid arteries of C57BL/6 mice were ligated near the carotid bifurcation, and the mice received K(1-5) for 4 weeks. Human umbilical vein endothelial cells were pretreated with K(1-5) before tumor necrosis factor-alpha (TNF-alpha) treatment to explore the anti-inflammatory effect of K(1-5).

RESULTS

The areas of the lesion in the aortas of ApoE-deficient mice that received K(1-5) treatment were notably decreased, and the formation of carotid neointima in the C57BL/6 mice was decreased by treatment with K(1-5). Expression of TNF-alpha-induced intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 was inhibited by K(1-5) treatment, possibly via downregulation of translocation of nuclear factor-kappaB and expression of reactive oxygen species.

CONCLUSIONS

K(1-5) reduced atherosclerosis and neointima formation in mice, possibly through inhibition of intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 expression in endothelial cells.

Intracoronary β‐irradiation enhances balloon‐injury‐induced tissue factor expression in the porcine injury model

Intracoronary brachytherapy (ICBT) effectively reduces restenosis but is associated with late thrombosis. Since tissue factor (TF) is an important mediator of arterial thrombosis, we tested the hypothesis that ICBT results in persistently augmented TF expression. Coronary arteries from 12 pigs were randomized to: control (C; no injury), oversized balloon injury (BI), or BI followed by ICBT. Animals were sacrificed at 1, 7, 14, or 60 days postprocedure, and coronary arteries collected for expression analyses and immunostaining. ICBT-treated arteries had higher TF antigen and activity at all time-points compared to BI arteries (Western blot: 16 571 +/- 2090 vs 10 135 +/- 2939 densitometric units, p = 0.001; ELISA: 0.42 +/- 0.13 nM vs 0.25 +/- 0.14 nM, p = 0.001; TF activity assay: 0.303 +/- 0.11 nM vs 0.18 +/- 0.07 nM, p = 0.01; immunohistochemical staining: 30.6 +/- 6.6% vs 11.5% +/- 3.2%, p = 0.01). TF expression increased following BI, increased further following ICBT, and persisted for the duration of the study. We conclude that TF expression increases after BI, but is further increased and persists for a longer duration following ICBT, suggesting that a TF-mediated mechanism may play a role in late thrombosis following ICBT.

Increased tissue transglutaminase expression in human atherosclerotic coronary arteries

BACKGROUND AND OBJECTIVE

Transglutaminase 2 (TGase 2) is a calcium-dependent cross-linking enzyme that catalyzes a covalent iso-peptide bond between two proteins. Interestingly, this catalysis can activate the nuclear factor-kappaB (NF-kappaB) through the polymerization of the inhibitory protein of NF-kappaB (I-kappaB). The objective of the present study was to investigate the expression of TGase 2 in the human atherosclerotic human coronary artery, and the possible roles of TGase 2 in NF-kappaB activation.

METHODS AND RESULTS

We explored whether expressions of TGase 2 and NF-kappaB are associated in atherosclerosis. Using human samples, we found that TGase 2 was markedly higher than normal in the neointimal tissue of atherosclerotic coronary arteries with atherosclerosis progression. TGase 2 activity was also increased approximately two-fold in the atherosclerotic vascular wall. In immunofluorescence analysis, NF-kappaB, COX-2, and TNF-alpha were co-localized at TGase 2-positive neointimal smooth muscle cells. A promoter assay test showed that NF-kappaB activity increased in both the human monocyte and human breast carcinoma cell by TGase 2, and that TGase 2-mediated NF-kappaB activation was reversed by TGase 2 siRNA.

CONCLUSION

According to these results, we suggest that TGase 2 may function as an activator in the NF-kappaB pathway; this effect may occur in the atherosclerotic vessel wall.

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.

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.

Inflammatory events in a vascular remodeling model induced by surgical injury to the rat carotid artery

1.--The aim of our study was to gain insight into the molecular and cellular mechanisms of the inflammatory response to arterial injury in a rat experimental model. 2.--Rats (five for each experimental time) were subjected to brief clamping and longitudinal incision of a carotid artery and monitored for 30 days. Subsequently, Nuclear Factor-kappaB (NF-kappaB) expression was measured by electrophoretic mobility shift assay. Heat shock protein (HSP) 27, HSP47 and HSP70 were evaluated by Western blot. Morphological changes of the vessel wall were investigated by light and electron microscopy. 3.--In injured rat carotid artery NF-kappaB activity started immediately upon injury, and peaked between 2 and 3 weeks later. Western blot showed a significant increase of HSP47 and HSP70 7 days after injury. At 2 weeks postinjury, HSP27 expression peaked. Light microscopy showed a neointima formation, discontinuity of the media layer and a rich infiltrate. Among infiltrating cells electron microscopy identified dendritic-like cells in contact with lymphocytes. 4.--Our model of surgical injury induces a significant inflammatory process characterized by enhanced NF-kappaB activity and HSPs hyperexpression. Dendritic-like cells were for the first time identified as a novel component of tissue repair consequent to acute arterial injury.

Gene deletion of NF-kappaB p105 enhances neointima formation in a mouse model of carotid artery injury

The role of nuclear factor kappa-B (NF-kappaB) p105 for vascular inflammatory gene expression and neointima formation after arterial injury was studied. Mice carotid arteries were injured by ligation. Vascular NF-kappaB activation was monitored using a NF-kappaB luciferase reporter mouse. Mice with gene deletion of the NF-kappaB p105 subunit (p50 precursor) and the corresponding wild types were assessed for vascular gene expression and neointimal hyperplasia. NF-kappaB was activated in the injured vessel wall in wild type mice, and this was accompanied by increased expression of the proinflammatory genes tumor necrosis factor alpha, interleukin 1 beta, and inducible nitric oxide synthase. In contrast, NF-kappaB p105 knockout mice had reduced expression of the inflammatory genes and enhanced neointima formation four weeks after ligation. Basic fibroblast growth factor (bFGF) gene expression increased after arterial ligation. A higher percentage of bFGF positive cells were found in lesions from NF-kappaB p105 knock out mice. These data indicate that the p105 subunit of NF-kappaB plays an essential role in vascular healing, and defects in NF-kappaB p105 promote neointima hyperplasia.

Countervailing effects of rapamycin (sirolimus) on nuclear factor-κB activities in neointimal and medial smooth muscle cells

OBJECTIVE

Local application of rapamycin (sirolimus) by drug-eluting stents prevents lumen obliteration after angioplasty by inhibition of neointimal hyperplasia. The effects of rapamycin on neointimal smooth muscle cells (niSMC) which are responsible for the occurrence of restenosis have not been investigated so far.

METHODS AND RESULTS

Rat niSMC and medial SMC (mSMC) were obtained from balloon catheter-injured arteries. The niSMC exhibited higher basal NF-kappaB activity and TNF-alpha mRNA levels. Nuclear protein binding to NF-kappaB-DNA was attenuated in niSMC by incubation with rapamycin (0.1 and 1 microg/ml) for 24 and 48 h. In contrast in mSMC, 0.1 microg/ml rapamycin had no effect and at 1 microg/ml even increased nuclear protein binding to NF-kappaB-DNA. After 12 h incubation, rapamycin (0.001-10 microg/ml) induced IkappaB-alpha protein in niSMC, whereas in mSMC it stimulated IkappaB-alpha at much lower levels. Prolonged rapamycin treatment (1 microg/ml for 72 h) had no effect on TNF-alpha mRNA level and NF-kappaB activity in niSMC, whereas it led to their increase in mSMC. Vascular endothelial growth factor (VEGF) secretion was higher in mSMC than in niSMC; rapamycin decreased VEGF levels in both cell types. Ultrastructural analysis suggested that rapamycin caused early signs of degeneration in niSMC, but enhanced protein synthesis in mSMC.

CONCLUSIONS

This study shows that rapamycin influences the inflammatory phenotypes of SMC in opposite directions: it reduces the high basal NF-kappaB activity in niSMC and enhances NF-kappaB activity and TNF-alpha expression in mSMC. In addition, rapamycin inhibits VEGF production regardless of the phenotype of SMC. These findings shed light on molecular mechanisms and structural changes underlying therapeutic applications of rapamycin in prevention of restenosis, inhibition of chronic transplant arteriosclerosis and reduction of secondary malignoma formation due to immunosuppression.

Activation of NF-kB and ERK1/2 after permanent focal ischemia is abolished by simvastatin treatment

We investigated the effects of simvastatin treatment on the expression of IL-1beta and MCP-1, the activity of NF-kB, and the signaling pathways related to NF-kB activation in a rat model of permanent middle cerebral artery occlusion (pMCAO). IL-1beta and MCP-1 expression, determined using RT-PCR, was enhanced by pMCAO; this effect was inhibited by the administration of simvastatin before ischemia. Pre-treatment with simvastatin abolished the ischemia-induced activation of NF-kB observed in vehicle-treated animals. The evaluation of signal transduction pathways, including extracellular signal-regulated kinase (ERK1/2), SAPK/JNK 46/54 and p38, indicated that only ERK1/2 phosphorylation was enhanced by ischemia, and this activation was prevented by simvastatin. ERK1/2-inhibitor, U0126, reduced brain ischemia but not cytokine induction. These results provide evidence that the HMG-CoA reductase inhibitor induces its effect in the protection of ischemic brain damage with a more complex mechanism which also involve anti-inflammatory properties rather than simple inhibition of ERK1/2 signaling pathway.

Early activation of internal medial smooth muscle cells in the rabbit aorta after mechanical injury: relationship with intimal thickening and pharmacological applications

1. Smooth muscle cells (SMC) participate in both inflammatory and dedifferentiation processes during atherosclerosis, as well as during mechanical injury following angioplasty. In the latter, we studied medial SMC differentiation and inflammation processes implicated early after de-endothelialization in relation to mechanical stresses. We hypothesized that activation of a subpopulation of SMC within the media plays a crucial role in the early phase of neointimal formation. 2. For this purpose, we used a rabbit model of balloon injury to study activation and differentiation of medial SMC in the early time after denudation and just before neointima thickening. Inflammation was evaluated by the expression of vascular cell adhesion molecule (VCAM)-1, integrin alpha4beta1 and nuclear factor (NF)-kB. Myosin isoforms and 2P1A2 antigen, a membrane protein expressed by rabbit dedifferentiated SMC, were used as markers of differentiation. 3. On day 2 after de-endothelialization, VCAM-1, alpha4beta1 and NF-kB were coexpressed by a well-defined subpopulation of SMC of the internal part of the media, in the vicinity of the blood stream. At the same time, the majority of SMC throughout the media expressed non-muscle myosin heavy chain-B (nm-MHC-B) and 2P1A2 antigen. On day 7, when intimal thickening appeared, SMC of the media were no longer activated, whereas some intimal SMC expressed the activation markers. Thus, after de-endothelialization, early dedifferentiation occurs in most of the medial SMC, whereas activation concerned only a subpopulation of SMC located in the internal media. Using the T-type voltage-operated calcium channel blocker mibefradil (0.1-1 micromol/L) in SMC culture, we showed that this agent exhibited an antiproliferative effect in a dose-dependent manner only on undifferentiated cells. 4. In conclusion, the results suggest that the activated SMC represent cells that are potentially able to migrate and participate in the intimal thickening process. Thus, the medial SMC inflammatory process, without any contribution of inflammatory cells, may represent a major mechanism underlying the development of intimal thickening following mechanical stress. In humans, inhibition of T-type calcium channels may be a tool to prevent the early proliferation step leading to neointimal formation.

Cytokine stimulation of pregnancy-associated plasma protein A expression in human coronary artery smooth muscle cells: inhibition by resveratrol

Through specific cleavage of proteins that bind and inhibit insulin-like growth factor-I (IGF-I), pregnancy-associated plasma protein-A (PAPP-A) enhances local IGF-I availability, and, consequently, receptor activation. PAPP-A expression is increased in experimental models of vascular injury and in human atherosclerotic plaque; however, little is known about the regulation of PAPP-A gene expression in vascular cells. In this study, we tested the hypothesis that proinflammatory cytokines involved in the vascular injury response stimulate PAPP-A gene expression in human coronary artery smooth muscle cells (hCASMC) in culture. Tumor necrosis factor (TNF)-α and interleukin (IL)-1β stimulated PAPP-A gene expression in a time- and dose-dependent manner. The effect of these cytokines appears to be at the level of transcription because actinomycin D completely prevented the induction of PAPP-A gene expression. Accumulation of PAPP-A in cell-conditioned medium paralleled mRNA synthesis, as did proteolytic activity against IGF binding protein-4 (IGFBP-4). Interestingly, pretreatment of hCASMC with resveratrol, a polyphenol found in the skin of grapes and in red wine purported to underlie the “French paradox,” inhibited TNF-α- and IL-1β-induced PAPP-A expression and, hence, its IGFBP-4 proteolytic activity. Resveratrol had no effect on basal PAPP-A expression and protease activity. Our finding that PAPP-A gene expression in hCASMC is stimulated by TNF-α and IL-1β suggests a mechanism for the regulation of PAPP-A in response to vascular injury that may contribute to the enhanced IGF-I bioactivity in intimal hyperplasia and atherosclerotic plaque development. Our results also suggest that PAPP-A may be a target of the cardiovascular system-protective effects of resveratrol.

Ursolic acid inhibits neointima formation in the rat carotid artery injury model

Triterpenoids are natural compounds that are found in a large variety of plants and vegetarian foods, and are used for medicinal purposes in many Asian countries. Pentacyclic triterpenes, such as ursolic acid, have been reported to exhibit anticancer and anti-inflammatory properties. The present study was designed to assess the effects of ursolic acid in the migration and proliferation of vascular smooth muscle cells (VSMC), and in a vascular injury model. The exposure of VSMC to ursolic acid results in a chemotaxis inhibition, in a reduction of the expression of proliferating cell nuclear antigen (PCNA) and in a disorganization of beta-tubulin and vimentin cytoskeletal proteins. Administration of ursolic acid in the rat carotid balloon catheter injury model shows a significant inhibition of neointimal hyperplasia. Thus, we have demonstrated that daily doses of 6 mg/kg body weight for 10 days reduce both the ratio of intimal to medial areas and the degree of stenosis by 80%, and suppress the expression of PCNA in both neointima and media. These results suggest that pentacyclic triterpenes may be of potential therapeutic value in vascular injury, and a possible treatment strategy for the prevention of the progression of atherosclerosis and restenosis after angioplasty.

Effect of pravastatin on malondialdehyde-modified low-density lipoprotein levels and coronary plaque regression as determined by three-dimensional intravascular ultrasound

We hypothesized that a reduction in atherogenic malondialdehyde-modified low-density lipoprotein (MDA-LDL) levels, which may antagonize the action of atheroprotective high-density lipoprotein cholesterol, leads to coronary plaque regression. This study investigated the effects of pravastatin on the serum levels of MDA-LDL and coronary atherosclerosis. In a 6-month prospective study, 75 patients with stable coronary artery disease were randomly assigned to a pravastatin-treatment group (n = 52) or a control group (n = 23). Volumetric analyses were performed in matched coronary artery segments by 3-dimensional intravascular ultrasound. Pravastatin therapy for 6 months resulted in a decrease in coronary plaque volume (14.4%, p <0.0001) and a corresponding reduction in serum MDA-LDL levels (12.7%, p = 0.0001). In the pravastatin treatment group, the percentage of change in plaque volume correlated with changes in the MDA-LDL and high-density lipoprotein cholesterol levels (r = 0.52 and -0.55, respectively, p <0.0001) but not with the changes in any other lipid levels. Multivariate regression analysis revealed that a reduced MDA-LDL level is an independent predictor of plaque regression, as was an increase in high-density lipoprotein cholesterol. In conclusion, these results suggest that the reduction in the MDA-LDL levels induced by pravastatin may serve as a novel marker of coronary atherosclerosis regression.

Roxithromycin is an inhibitor of human coronary artery smooth muscle cells proliferation: a potential ability to prevent coronary heart disease

Roxithromycin (RXM), a macrolide antibiotic, is used in clinical trials to address secondary prevention of coronary heart disease. However, the effects of RXM on human coronary artery smooth muscle cells (CASMC) proliferation remain unclear. Human CASMC were stimulated with growth medium containing 5% fetal bovine serum and growth factors. RXM at 1 or 10 microg/ml, which are relevant to the therapeutic plasma levels, significantly suppressed mitogen-induced CASMC proliferation, assessed by WST-1 assay and cell counting. Flow cytometry analysis demonstrated that RXM suppressed mitogen-induced G1 to S progression on cell cycle. Western blot showed that RXM inhibited phosphorylation of retinoblastoma gene products, reduced protein levels of cyclin D1 and A, and restored downregulation of cyclin-dependent kinase (CDK) inhibitor p27kip1. The activities of CDK4 and CDK2 were suppressed by RXM without affecting their protein levels. When transfected with both IkappaB kinase alpha and beta constructs as nuclear factor-kappa B (NF-kappaB) activator, CASMC entered S phase at 24 h, and RXM inhibited it. Electrophoretic mobility shift assay and immunostaining of NF-kappaB p65 demonstrated that RXM inhibited mitogen-induced NF-kappaB activation. These results indicate that RXM is an inhibitor of human CASMC proliferation through modulating cell cycle regulatory proteins and inhibiting NF-kappaB signaling pathway.

Local administration of NF-kappa B decoy oligonucleotides to prevent restenosis after balloon angioplasty: an experimental study in New Zealand white rabbits

PURPOSE

To evaluate the efficacy of NF-kappa B oligonucleotides (ODN) administered by local administration with the channeled balloon catheter to prevent restenosis after balloon angioplasty in restenotic iliac arteries of New Zealand white rabbits.

MATERIALS AND METHODS

In vitro, 8000 rabbit vascular smooth muscle cells (rVSMC) where transfected with a liposomal carrier (TfX50) with 100 ng of decoy and scrambled ODN. Inhibition of proliferation was measured using a MTT assay after 24 hours in comparison to control. In vivo, 22 male New Zealand White rabbits were fed a 1% cholesterol diet and received denudation of both common iliac arteries with a 3 mm balloon catheter to induce an arterial stenosis. Four weeks after stenosis induction, local application of NF-kappa B in two different concentrations (1 mug: n = 14; 10 mug: n = 8) was performed randomly on one common iliac artery. Scrambled oligonucleotides without specific binding capacities were injected into the contralateral side. The channeled balloon catheter allows simultaneous balloon dilation (8 atm) of the stenosis and local application of a drug solution (2 atm). Four weeks after local drug delivery the animals were killed and the vessels were excised and computerized morphometric measurements were performed.

RESULTS

NF-kappa B decoy ODN but not scrambled ODN inhibited proliferation of rVSMC in vitro. Following local ODN application in the animals, no acute vascular complications were seen. NF-kappa B ODN resulted in a statistically non significant reduction of neointimal area compared to the control group. The neointimal area was 0.97 mm(2) using 1 mug NF-kappa B ODN compared to 0.98 mm(2) in the control group. The higher dose resulted in a neointimal area of 0.97 mm(2) compared to 1.07 mm(2) at the control side.

CONCLUSIONS

Local drug delivery of NF-kappa B ODN using the "channeled balloon" catheter could not reduce neointimal hyperplasia in stenostic rabbit iliac arteries. Application modalities have to be improved to enhance the effect of the local application to prevent restenosis after balloon angioplasty.

Effect of exposure to cigarette smoke on carotid artery intimal thickening: the role of inducible NO synthase

OBJECTIVE

We investigated the role of inducible NO synthase (iNOS) in intimal thickening with exposure to cigarette smoke (CS).

METHODS AND RESULTS

Intimal thickening in wild-type (WT) and iNOS-deficient (iNOS-/-) mice subjected to CS exposure was induced by placement of a cuff around the carotid artery. CS exposure in WT mice was associated with increased arterial iNOS expression, superoxide production, activator protein-1 (AP-1) activation, and serum NO. Intimal thickening 21 days after cuff placement was significantly greater in mice exposed to CS compared with air (0.023+/-0.013 mm(2) versus 0.009+/-0.008 mm(2); P<0.05). iNOS inhibitor mercaptoethylguanidine-treated WT mice exposed to CS had reduced iNOS activity and intimal thickening (0.006+/-0.005 mm(2); P<0.05). Intimal thickening was significantly less in iNOS-/- mice compared with WT mice (0.006+/-0.005 mm(2); P<0.01) and was not augmented with CS (0.002+/-0.002 mm(2)). The aryl hydrocarbon receptor (AhR) was detected in arteries in vivo and in smooth muscle cells (SMCs) in vitro. CS condensate treatment of SMCs increased AhR binding to the core xenobiotic-responsive element of the iNOS promoter and increased iNOS expression.

CONCLUSIONS

Increased arterial expression of iNOS, mediated at least in part by AhR signaling, may be an important mechanism by which CS increases carotid intimal thickening. CS exposure in mice was associated with increased arterial iNOS expression, superoxide production, AP-1 activation, serum NO expression, and intimal thickening. Inhibition or deletion of iNOS abrogated the effects of CS.

Activation of nuclear factor-kappaB and correlation with elevated plasma c-reactive protein in patients with unstable angina

BACKGROUND

Unstable coronary syndromes are currently believed to be caused by rupture of an atherosclerotic plaque due to local events, which may be of general inflammatory etiology. There is increasing evidence that nuclear factor-kappaB (NF-kappaB) is a key transcription factor in controlling gene expression concerning inflammatory response, and that plasma concentrations of C-reactive protein (CRP) is a sensitive marker of inflammation in unstable coronary syndromes. However, whether NF-kappaB activation is associated with coronary heart disease (CHD) activity as well as plasma CRP level has been less well investigated. The aim of this study was to explore whether NF-kappaB activation was associated with CHD activity and plasma CRP elevation in patients with unstable angina (UA).

METHODS

NF-kappaB activity derived from white blood cells circulating in 33 patients with CHD was determined by electrophoretic mobility shift assay. Of these, 16 had UA and were within 24h of the last episode of chest pain. The remaining 17 were being evaluated for stable angina (SA). The CRP was also evaluated in both groups using a high-sensitivity ELISA.

RESULTS

There was marked NF-kappaB activation and elevated levels of CRP in UA group compared with SA group (4.02+/-0.71 AU versus 1.24+/-0.23 AU and 5.0+/-0.7mg/l versus 1.4+/-0.4mg/l, respectively, P<0.01), no NF-kappaB signal was observed in normal subjects (n=10). The NF-kappaB activation had a positive correlation with levels of CRP in patients with UA (n=11, gamma=0.771, P<0.01), but had no relationship between other clinical characteristics and the status of NF-kappaB activation.

CONCLUSIONS

Our data suggest that inflammation is an important feature of unstable coronary artery disease, and both NF-kappaB and CRP are useful markers for the detection of UA or vulnerable plaques.

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

PURPOSE

Vascular injury and inflammation are associated with elaboration of a number of cytokines that signal through multiple pathways to act as smooth muscle cell (SMC) mitogens. Activation of the nuclear factor-kappa B (NF-kappaB) transcription factor is essential for SMC proliferation in vitro and is activated by vascular injury in vivo. Activation of NF-kappaB is controlled by several upstream regulators, including the inhibitors of kappa B (IkappaB). These proteins bind to and keep NF-kappaB inactivated. The purpose of this study was to determine whether adenoviral gene transfer of a mutated IkappaBalpha super-repressor (AdIkappaBalphaSR) could inhibit development of intimal hyperplasia in vivo and to investigate how over-expression of this construct influences in vitro SMC proliferation and cell cycle regulatory proteins.

METHODS

A rat carotid injury model was used to study prevention of intimal hyperplasia. Arteries were assayed 14 days after injury and infection with AdIkappaBalphaSR or adenoviral beta-galactosidase (AdLacZ). Untreated SMC or SMC infected with AdLacZ or AdIkappaBalphaSR were stimulated with 10% fetal bovine serum, interleukin-1beta, or tumor necrosis factor-alpha. Electrophoretic mobility shift assays were used to assay for NF-kappaB activation. Protein levels of IkappaBalpha and cyclin-dependent kinase inhibitors p21(Cip1/Waf1) and p27(Kip1) were determined with Western blot analysis. Proliferation was measured with (3)H-thymidine incorporation assays.

RESULTS

AdIkappaBalphaSR inhibited the development of intimal hyperplasia by 49% (P <.05). Infection with AdIkappaBalphaSR significantly suppressed in vitro SMC proliferation when stimulated with serum, interleukin 1, or tumor necrosis factor alpha, and did not result in cell death. Inhibition of proliferation was associated with increased p21(Cip1/Waf1) and p27(Kip1) protein levels.

CONCLUSIONS

Gene transfer of IkappaBalpha super-repressor inhibited development of intimal hyperplasia in vivo and SMC proliferation in vitro. The antiproliferative activity may be related to cell cycle arrest through upregulation of the cyclin-dependent kinase inhibitors p21 and p27. Overexpression of IkappaBalpha may be a future therapeutic option in treatment of vascular diseases.

2-Cyclopenten-1-one and prostaglandin J2reduce restenosis after balloon angioplasty in rats: role of NF-κB

The aim of this study was to evaluate, using a rat model of balloon angioplasty, whether prostaglandin (PG) J(2) and 2-cyclopenten-1-one are able to reduce restenosis. We found that both PGJ(2) and 2-cyclopenten-1-one, administered by local application on carotid arteries, caused a dose-dependent inhibition of neointimal formation. Furthermore, both agents prevented vascular negative remodeling. The effect of these compounds on restenosis was correlated with an inhibition of nuclear factor-kappaB (NF-kappaB) activation as well as of intercellular adhesion molecule-1 (ICAM-1) protein expression in injured carotid arteries of control animals. Our results show that cyclopentenone PGs and their derivatives reduce restenosis and may have therapeutic relevance for the prevention of human restenosis.

Aspirin protects Caco-2 cells from apoptosis after serum deprivation through the activation of a phosphatidylinositol 3-kinase/AKT/p21Cip/WAF1pathway

Our previous studies indicated that millimolar doses of aspirin induced growth arrest and resistance to anticancer drug treatment in Caco-2 cells. The present study was designed to better elucidate at the molecular level the effect of aspirin treatment on pathways that regulate cell death during serum withdrawal. Caco-2 cells were cultured under serum deprivation in the presence or absence of aspirin. Effects on cell cycle, phosphatidylinositol 3-kinase (PI3-kinase) and mitogen-activated protein (MAP) kinase pathways were investigated. We found that aspirin, but not the selective cyclooxygenase-2 inhibitor N-[2-(cyclohexyloxyl)-4-nitrophenyl]-methane sulfonamide (NS-398); prevented apoptosis and G2/M transition after prolonged Caco-2 cells serum deprivation. Aspirin-dependent inhibition of apoptosis and G2/M transition was prevented by treatment with the PI3-kinase inhibitor 2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one (LY294002), but not with the MAP kinase kinase inhibitor 2'-amino-3'-methoxyflavone (PD98059). The effects of aspirin were mediated at molecular levels, through activation of PI3-kinase/AKT pathway and increase in the p21Cip/WAF1 level. The ability of aspirin to activate AKT protein was observed also in presence of etoposide cotreatment. Our data indicate a new intracellular target of aspirin with potential clinical impact for treatment schedules involving both anticancer agents and aspirin in malignancies.

Esculetin inhibits Ras-mediated cell proliferation and attenuates vascular restenosis following angioplasty in rats

The proliferation of vascular smooth muscle cells (VSMCs) induced by injury to the intima of arteries is an important etiologic factor in vascular proliferative disorders such as atherosclerosis and restenosis. Esculetin, derived from the Chinese herb Artemisia scoparia, is well known as a lipoxygenase inhibitor. We have investigated the inhibitory effects of esculetin on VSMC proliferation and intimal hyperplasia by balloon angioplasty in the rat. We determined, using [3H]thymidine incorporation and the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, that esculetin inhibited the proliferation of VSMCs via a lipoxygenase-independent pathway. Three predominant signaling pathways were identified to be inhibited by esculetin: (a) the activation of p42/44 mitogen-activated protein kinase (MAPK) and the downstream effectors of c-fos and c-jun immediate early genes by means of western and reverse transcription-polymerase chain reaction (RT-PCR) analyses; (b) the activation of nuclear factor-kappaB (NF-kappaB) and activator protein-1 (AP-1), using the electrophoretic mobility shift assay; and (c) the activation of phosphoinositide 3-kinase (PI 3-kinase) and cell cycle progression, by western blot analysis and flow cytometric detection. Furthermore, esculetin also profoundly inhibited Ras activation, a shared upstream event of the above signaling cascades. In vascular injury studies, intraperitoneal administration of esculetin significantly suppressed intimal hyperplasia induced by balloon angioplasty. We conclude that esculetin blocks cell proliferation via the inhibition of an upstream effector of Ras and downstream events including p42/44 MAPK activation, PI 3-kinase activation, immediate early gene expression, as well as NF-kappaB and AP-1 activation. It also inhibits intimal hyperplasia after balloon vascular injury in the rat, indicating the therapeutic potential for treating restenosis after arterial injury.

Inhibition of NFkappaB activation using cis-element 'decoy' of NFkappaB binding site reduces neointimal formation in porcine balloon-injured coronary artery model

Application of DNA technology to regulate the transcription of disease-related genes has important therapeutic potential. The transcription factor NFkappaB plays a pivotal role in the transactivation of inflammatory and adhesion molecule genes, leading to vascular lesion formation. Double-stranded DNA with high affinity for NFkappaB may be introduced as 'decoy' cis elements to bind NFkappaB and block the activation of genes mediating inflammation, resulting in effective drugs for treating intimal hyperplasia. In this study, we tested the feasibility of NFkappaB decoy therapy to treat neointimal formation in a porcine coronary artery balloon injury model as a pre-clinical study. An angioplasty catheter was introduced into the left anterior descending coronary artery of the pig to cause vascular injury. First, we tested the feasibility of transfection of FITC-labeled NFkappaB decoy ODN using a hydrogel balloon catheter. Fluorescence due to NFkappaB decoy ODN could be detected throughout the medial layer. Therefore, we transfected NFkappaB decoy ODN into the balloon-injured LAD using a hydrogel catheter. Histological evaluation demonstrated that the neointimal area in the balloon-injured artery was significantly reduced by NFkappaB decoy ODN as compared to scrambled decoy ODN at 1 week after single transfection, accompanied by a significant reduction in PCNA-positive stained cells (P < 0.01). Interestingly, the reduction of ICAM-positive staining was observed, accompanied by the inhibition of migration of macrophages. Of importance, intravascular ultrasound (IVUS) confirmed that neointimal area in the balloon-injured artery was significantly reduced by NFkappaB decoy ODN at 4 weeks after transfection (P < 0.01). Interestingly, the inhibition of neointimal area was only limited to the lesion transfected with NFkappaB decoy ODN, while other lesions without NFkappaB decoy ODN demonstrated a marked increase in neointimal formation. Here, we report the successful in vivo transfer of NFkappaB decoy ODN using a hydrogel catheter to inhibit vascular lesion formation in balloon-injured porcine coronary artery.

Growth factors enhance interleukin-1 beta-induced persistent activation of nuclear factor-kappa B in rat vascular smooth muscle cells

OBJECTIVE

Activation of extracellular signal-regulated kinases (ERKs) is required for interleukin-1beta to persistently activate nuclear factor (NF)-kappaB and concomitantly express inducible NO synthase (iNOS) in rat vascular smooth muscle cells (VSMCs). The present study examined whether platelet-derived growth factor (PDGF) or epidermal growth factor (EGF) could influence the VSMC response to interleukin-1beta via an ERK-related signaling pathway.

METHODS AND RESULTS

Treatment of VSMCs with PDGF or EGF alone potently induced ERK phosphorylation and DNA synthesis but did not induce NF-kappaB activation or iNOS expression. However, either PDGF or EGF markedly enhanced interleukin-1beta-induced persistent NF-kappaB activation and iNOS expression but did not affect the early and transient NF-kappaB activation. Growth factor-induced DNA synthesis was attenuated in the presence of interleukin-1beta. Inhibition of ERK phosphorylation with selective inhibitors (PD98059 or U0126) attenuated interleukin-1beta-induced persistent NF-kappaB activation and iNOS expression in either the absence or presence of the growth factors.

CONCLUSIONS

These results indicate that interleukin-1beta-induced expression of NF-kappaB-dependent genes, such as iNOS, is potentiated in the presence of growth factors through a mechanism requiring ERK-dependent enhanced NF-kappaB activation, and the results also suggest that NF-kappaB activation is not required for PDGF or EGF to trigger DNA synthesis in VSMCs.

Laser myocardial revascularization modulates expression of angiogenic, neuronal, and inflammatory cytokines in a porcine model of chronic myocardial ischemia

BACKGROUND

Controversy exists whether transmyocardial laser revascularization (TMR) is associated with angiogenesis or neuromodulation and whether these are time-dependent phenomena. Accordingly, we performed a time-course analysis of the expression of angiogenic and neuronal factors following experimental percutaneous TMR.

METHODS AND RESULTS

Five weeks after placing ameroid constrictors on the circumflex coronary artery, 16 pigs underwent left ventricular mapping guided TMR using Ho:YAG laser (2 J x 1 pulse) at 30 sites directed at the ischemic zones and 11 animals were ischemic controls. Histology and immunostaining were obtained at 1 and 2 weeks (4 TMR and 3 controls at each time point) and at 4 weeks (8 TMR and 5 controls) for vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), nerve growth factor (betaNGF), substance P (SP), and monocyte chemoattractant protein-1 (MCP-1). Immunoreactivity was scored using a digital image analysis system. Factor VIII staining was used for blood vessel counting. Enhanced regional expression of VEGF, bFGF and MCP-1 in the TMR group was noted at 1 and 2 weeks with a threefold increase at 4 weeks following TMR compared to controls. BetaNGF expression in the TMR group was enhanced at 1 and 2 weeks with subsequent decline at 4 weeks to the controls level. SP expression was not significantly different between groups at all time points. There was a twofold increase in the number of blood vessels in the TMR group at 4 weeks, which was not apparent earlier.

CONCLUSIONS

These immunohistological findings suggest that cytokines expression compatible with angiogenesis and neuromodulation occurs early after TMR. Up-regulation of angiogenic and inflammatory cytokines may be more sustained than neuromodulation.