Artery Lesion Formation Research Articles

Role of transglutaminases in cuff-induced atherosclerotic lesion formation in femoral arteries of ApoE3 Leiden mice

Transglutaminases play an important role in vascular remodeling, calcification, cell adhesion and endothelial barrier function. In this study we investigate the influence of combined inhibition of both tissue-type transglutaminase (TG2) and the plasma transglutaminase FXIIIA on early lesion development. Methods A cuff was placed around the femoral arteries of ApoE3 Leiden mice while fed a Western type diet to induce atherosclerotic lesion development. An osmotic minipump was placed in the intraperitoneal cavity containing an irreversible inhibitor of TG2 and FXIIIA activity ((1,3,4,5-tetramethyl-2-[(2-oxopropyl)thio]imidazolium chloride, Zedira). Atherosclerotic lesion composition was analyzed using immunohistochemistry and RT-PCR. Results Inhibition of transglutaminases did not influence lesion size or geometric remodeling of the vessels. However, systemic transglutaminase inhibition resulted in 41% less macrophage infiltrate in the media of the vessels. Additional in vitro experiments on HL60 cells confirmed a decreased migratory response during transglutaminase inhibition. Conclusion Inhibition of TG2 and FXIIIA during early development of lesions reduced the macrophage content in the media of atherosclerotic vessels, while not affecting lesion size or geometric remodeling.

Culprit Coronary Lesions Requiring Percutaneous Coronary Intervention After Vascular Surgery Often Arise From In-Stent Restenosis of Bare Metal Stents

The natural history of coronary artery disease (CAD) after vascular surgery is poorly defined. The aim of this study was to determine the temporal change of coronary artery lesions requiring revascularization with a percutaneous coronary intervention (PCI) after elective vascular surgery and to determine the utility of preoperative biomarkers on predicting those patients at risk for new coronary lesions. The Coronary Artery Revascularization Prophylaxis Trial tested the long-term survival benefit of coronary artery revascularization before elective vascular surgery. Among randomized patients who subsequently required PCI after surgery, the stenosis of the culprit lesion from the follow-up angiogram was compared with the preoperative vessel stenosis at the identical site on the baseline angiogram. A total of 30 patients underwent PCI for progressive symptoms at a median of 11.5 (interquartiles: 4.5-18.5) months postsurgery. Of 30 patients, 16 (53%) had nonobstructive CAD preoperatively (group 1) with a stenosis that increased from 17 +/- 6% to 91 +/- 2% (P < 0.01) and 14 (47%) had severe CAD at the culprit site preoperatively (group 2), with a stenosis that increased 89 +/- 2% (P = 0.15). The only biomarker that was an identifier of early coronary artery lesion formation in group 1 compared with group 2 patients was a higher baseline homocysteine level (14.6 +/- 1.4 vs. 10.6 +/- 0.7 mg/dL; P = 0.02). Culprit coronary artery lesions requiring PCI after an elective vascular operation often arise from in-stent restenosis. Therapies that either stabilize existing plaques or prevent restenosis, particularly among patients with elevated homocysteine levels, have the greatest promise for improving postoperative outcomes.

Nuclear Receptor Nurr1 Is Expressed In and Is Associated With Human Restenosis and Inhibits Vascular Lesion Formation In Mice Involving Inhibition of Smooth Muscle Cell Proliferation and Inflammation

Restenosis is the major drawback of percutaneous coronary interventions involving excessive activation and proliferation of vascular smooth muscle cells (SMCs). The nuclear receptor Nurr1 is an early response gene known mainly for its critical role in the development of dopamine neurons. In the present study, we investigated Nurr1 in human and experimental vascular restenosis. In a prospective cohort of 601 patients undergoing percutaneous coronary intervention, including stent placement, we found a strong association between Nurr1 haplotypes and in-stent restenosis risk. Furthermore, Nurr1 is specifically expressed in human in-stent restenosis and induced in cultured human SMCs in response to serum or tumor necrosis factor-alpha. Lentivirus-mediated gain- and loss-of-function experiments in SMCs demonstrated that overexpression of Nurr1 inhibited proliferation, consistent with increased expression of the key cell-cycle inhibitor p27(Kip1), whereas Nurr1 silencing enhanced SMC growth. The tumor necrosis factor-alpha-induced proinflammatory response of SMCs is inhibited by Nurr1, as reflected by reduced interleukin-1beta, tumor necrosis factor-alpha, and monocyte chemoattractant protein-1 expression. Consistent with our in vitro data, endogenous Nurr1 reduced wire injury-induced proliferation and vascular lesion formation in carotid arteries of ApoE(-/-) mice. Nurr1 haplotypes are associated with human restenosis risk, and Nurr1 is expressed in human in-stent restenosis. In SMCs, Nurr1 inhibits proliferation and inflammatory responses, which explains the inhibition of SMC-rich lesion formation in mice. The recently identified small-molecule drugs that enhance the activity of Nurr1 reveal this nuclear receptor as an attractive novel target for (local) intervention in restenosis.

Inhibition of arterial lesion progression in CD16-deficient mice: evidence for altered immunity and the role of IL-10

Given the importance of IgG Fc receptors in immune regulation, we hypothesized that Fcg receptor type III (FcgRIII, CD16) plays an important role in atherogenesis. We therefore analysed the formation of arterial lesions in LDL receptor-deficient (LDLR(-/-)) and FcgRIII(-/-)xLDLR(-/-) double knockout mice at three different points up to 24 weeks of exposure to a high-fat diet. Analysis of Oil Red-O-stained sections revealed no difference in lesion formation between strains after 6 weeks of a high-fat diet, and a modest decrease after 14 weeks in double knockouts relative to LDLR(-/-) controls. After 24 weeks, lesion formation was decreased in the aortic root (30%) and innominate artery (50%) in FcgRIII double knockouts relative to LDLR(-/-) controls. Analysis of peripheral CD4+ T-cells by intracellular flow cytometry from double knockouts after 24 weeks of a high-fat diet revealed statistically significant increases in the percentages of cells producing interferon-gamma, interleukin (IL)-10, and IL-4 relative to controls, differences that were also observed by analyses of whole aortas for cytokine mRNA levels. As determined by flow cytometry, FcgRIII deficiency resulted in an expansion of CD4+ cells and an increase in the CD4 to CD8 ratio. Analysis of plasma anti-oxidized LDL (OxLDL) antibodies by chemiluminescent assay revealed that IgG1 and IgG2c titers to OxLDL were increased in FcgRIII (-/-)xLDLR(-/-) double knockouts relative to LDLR(-/-) controls, while total IgG levels were similar. These results reveal altered immunity in FcgRIII(-/-)xLDLR(-/-) mice and a reduction in lesion formation associated with increased production of IL-10 by an expansion of CD4+ T-cells. The reduction in lesion formation was manifest well after evidence of an immune response to OxLDL, suggesting that FcgRIII contributes to lesion progression in murine atherosclerosis.

Adaptive immunity and atherosclerosis

Atherosclerosis involves the formation of inflammatory arterial lesions and is one of the most common causes of death globally. It has been evident for more than 20 years that adaptive immunity and T cells in particular regulate the magnitude of the atherogenic pro-inflammatory response. T cells also influence the stability of the atherosclerotic lesion and thus the propensity for thrombus formation and the clinical outcome of disease. This review summarizes our current understanding of T cells in atherogenesis, including which antigens they recognize, the role of T cell costimulation/coinhibition, and their secretion of pro- and anti-inflammatory mediators. Furthermore, we outline future areas of research and potential clinical intervention strategies.

Neutropenia in the acute phase of Kawasaki disease and prevention of coronary artery aneurysm

The significance of neutropenia in Kawasaki disease (KD) has not been fully elucidated as yet. Subjects were retrospectively sampled from two clinical trials. These patients treated with aspirin alone (ASA) and PolyglobinN-Bayel (PolyN) given as i.v. immunoglobulin were categorized as ASA-early (n = 0), ASA-late (n = 8), PolyN-early (n = 18), or PolyN-late (n = 27) based on the therapy administered and the incidence of neutropenia before the 10th day of illness (DI) and after 11 DI. Data regarding the time of onset of neutropenia, and incidence of coronary artery lesion (CAL) formation were obtained. P < 0.05 was considered statistically significant. No patients in the ASA group exhibited neutropenia within 10 DI. The time of onset of neutropenia in the PolyN-early group was 8 +/- 1.3 DI. That in the PolyN-late group (19.8 +/- 8 DI) was earlier than in the ASA-late group (26.6 +/- 14 DI; P < 0.025). PolyN-early patients had a lower incidence of CAL formation than ASA-non patients (patients without neutropenia in the ASA group; P = 0.00019) and ASA-late patients (P = 0.04). That in the PolyN-early group tended to be lower than in the PolyN-late group (P < 0.1). Early neutropenia indicated that circulating neutrophils within 10 DI may play an indispensable role in the following sequence to CAL formation in KD.

Vaccination against atherosclerosis? Induction of atheroprotective immunity

Atherosclerosis involves the formation of inflammatory arterial lesions and is one of the most common causes of death globally. It has been evident for more than 20 years that adaptive immunity regulates the magnitude of the atherogenic proinflammatory response. T cells may also influence the stability of the atherosclerotic lesion and thus the propensity for thrombus formation and the clinical outcome of disease. Immunization of hypercholesterolemic animals with low-density lipoprotein preparations reduces atherosclerosis, suggesting that vaccination may represent a useful strategy for disease prevention or modulation. This review summarizes our current understanding of the role immunity in atherosclerosis and outlines strategies for antigen-specific prevention of this disease.

Notch signaling regulates the differentiation of bone marrow-derived cells into smooth muscle-like cells during arterial lesion formation

Bone marrow- (BM-) derived cells can differentiate into smooth muscle-like cells (SMLC), resulting in vascular pathogenesis. However, the molecular mechanism of the differentiation remains unknown. We have recently reported that Notch signaling promotes while a Notch target HERP1 inhibit the differentiation of mesenchymal cells to SMC. During the differentiation of BM-derived mononuclear cells into smooth muscle α-actin (SMA)-positive cells, expression of Jagged1 and SMC-specific Notch3 was increased. Blocking Notch with γ-secretase inhibitor prevented the induction of SMA. Wire-mediated vascular injury was produced in femoral arteries in mice transplanted with green fluorescent protein (GFP)-positive cells. Many double-positive cells for GFP/Jagged1 or GFP/Notch3 were detected in the thickened neointima. In contrast, only a few SMA-positive cells were positive for GFP in neointima where HERP1, a suppressor for Notch, were abundantly expressed. In conclusion, Notch-HERP1 pathway plays an important role in differentiation of BM-derived mononuclear cells into SMLC.

Translational Mini-Review Series on Immunology of Vascular Disease: Inflammation, infections and Toll-like receptors in cardiovascular disease

Cardiovascular disease, in which atherosclerosis is the major underlying cause, is currently the largest cause of death in the world. Atherosclerosis is an inflammatory disease characterized by the formation of arterial lesions over a period of several decades at sites of endothelial cell dysfunction. These lesions are composed of endothelial cells, vascular smooth muscle cells, monocytes/macrophages and T lymphocytes (CD4(+)). As the lesions progress some can become unstable and prone to disruption, resulting in thrombus formation and possibly a myocardial infarction or stroke depending upon the location. Although the exact triggers for plaque disruption remain unknown, much recent evidence has shown a link between the incidence of myocardial infarction and stroke and a recent respiratory tract infection. Interestingly, many reports have also shown a link between a family of pattern recognition receptors, the Toll-like receptors, and the progression of atherosclerosis, suggesting that infections may play a role in both the progression of atherosclerosis and in inducing the more severe complications associated with the disease.

Syndrome d’apnées obstructives du sommeil, hypertension artérielle et artère

Obstructive sleep apnea syndrome (OSAS), due to upper airway collapse, is frequent but still underestimated. The dose-response relation between OSAS and hypertension (HTN) is now well established. Logically, therefore, blood pressure must be tested in every apneic patient, if necessary by ambulatory blood pressure monitoring. Multiple mechanisms explain this relation, most importantly the increase in sympathetic activity during apnea episodes. OSAS-related hypertension has several characteristics: it is highly prevalent, predominantly diastolic and nocturnal, and frequently affects non-dippers; and the HTN tends to be resistant to treatment. OSAS promotes the formation of arterial lesions (parietal thickening of the carotid artery, increased aortic stiffness, and endothelial dysfunction); the more severe the OSAS, the more severe the lesions. The beneficial effects on blood pressure of continuous positive airway pressure (CPAP), the benchmark treatment for OSAS, are still debated but appear to be significant for untreated or refractory hypertension, for severe OSAS, and when CPAP compliance is good. It also seems promising for the reduction of arterial lesions linked to OSAS.

Adult progenitor cells in vascular remodeling during atherosclerosis

The mobilization and recruitment of bone marrow-derived, circulating or tissue resident progenitor cells giving rise to smooth muscle-like cells have been implicated in neointima hyperplasia after arterial injury and in accelerated forms of arterial lesion formation, e.g., transplant arteriopathy or graft vasculopathy. By contrast, convincing evidence has emerged that the vascular homing of endothelial progenitor cells (EPCs) contributes to endothelial recovery, thus limiting neointima formation after arterial injury. In the chronic context of primary atherosclerosis, plaque progression and destabilization, a more complex picture has become apparent. In patients with coronary artery disease, the number and function of EPCs have been linked with an improved endothelial function or regeneration, but have been inversely correlated with cardiovascular risk. In animal models, however, the injection of bone marrow cells or EPCs, or the application of stem-cell mobilizing factors, have been associated with an exacerbation of atherosclerosis and unstable plaque phenotypes, whereas the contribution of bone marrow-derived smooth muscle progenitors to primary atherosclerosis appears to be rather confined. Here, we discuss crucial biochemical cues, namely chemokines, adhesion molecules, growth factors and pharmacological means that guide and control the context-specific mobilization, recruitment and fate of vascular progenitor cells in arterial remodeling during atherosclerosis.

Unchecked thrombin is bad news for troubled arteries

Thrombin is clearly a key trigger of thrombosis, the proximal cause of most morbidity and mortality in atherosclerotic cardiovascular disease. Might thrombin also contribute to longer-term, structural changes in the arterial wall that promote narrowing and clotting? A study in this issue of the JCI argues that it can. Aihara et al. report that haploinsufficiency of heparin cofactor II, a glycosaminoglycan-dependent thrombin inhibitor, exacerbates injury- or hyperlipidemia-induced arterial lesion formation in mice, possibly by excessive thrombin signaling through protease-activated receptors (see the related article beginning on page 1514).

Diverse Contribution of Bone Marrow–Derived Cells to Vascular Remodeling Associated With Pulmonary Arterial Hypertension and Arterial Neointimal Formation

Recent evidence suggests that bone marrow (BM)-derived cells may differentiate into vascular cells that participate in arterial repair and/or lesion formation. However, it remains uncertain whether BM-derived cells also can participate in vascular remodeling associated with pulmonary arterial hypertension. The BM of Sprague-Dawley rats was reconstituted with that of green fluorescent protein-transgenic rats. The BM-chimeric rats were injected intraperitoneally with 60 mg/kg monocrotaline after unilateral subpneumonectomy, and they concurrently underwent wire-mediated endovascular injury in femoral artery. After 28 days, they had elevated right ventricular systolic pressure (58.8+/-5.4 versus 20.4+/-2.4 mm Hg in sham-control; P<0.01). The pulmonary arterioles were markedly thickened, with an infiltration of green fluorescent protein-positive macrophages into the perivascular areas. The endothelium of pulmonary arterioles contained only a few green fluorescent protein-positive cells, and green fluorescent protein-positive cells were seldom detected as smooth muscle cells in the lesions of thickened pulmonary arterioles. In contrast, BM-derived smooth muscle-like cells could be readily detected in the thickened neointima and media of the wire-injured femoral artery. Moreover, intravenous injection of 1x10(8) BM cells from young rats had no beneficial effects on pulmonary hypertension, pulmonary arterial remodeling, or survival in the aged rats treated with monocrotaline plus unilateral subpneumonectomy. No injected BM cell was identified as an endothelial cell or a smooth muscle cell. These results suggest that BM-derived cells can participate in arterial neointimal formation after mechanical injury, whereas they do not contribute substantially to pulmonary arterial remodeling associated with monocrotaline-induced pulmonary arterial hypertension in the pneumonectomized rats.

Serum homocysteine and tumor necrosis factor-alpha levels after intravenous gammaglobulin treatment in patients with Kawasaki disease

Purpose:Homocysteine is a strong and independent risk factor for cardiovascular disease. The deleterious effects of homocysteine included endothelial dysfunction, arterial intimal-medial thickening, wall stiffness and procoagulant activity. However, the precise mechanism responsible for homocysteine release in children with coronary artery disease is still unknown. The purpose of this study was to investigate serum homocysteine and tumor necrosis factor(TNF)-α levels and identify whether these levels had any association with the development of coronary artery lesions in Kawasaki disease(KD). Methods:Serum homocysteine and TNF-α levels were measured in 24 KD patients(group 1, eight patients with normal coronary artery; group 2, 16 patients with coronary artery lesions) and 21 controls(group 3, 10 afebrile controls; group 4, 11 febrile controls). Blood samples were drawn from each study group before and after intravenous immunoglobulin(IVIG) therapy and in the convalescent stage. Results:The homocysteine levels before IVIG therapy were significantly higher in group 1 than in group 3, and in group 2 than in group 3 and 4. The TNF-α levels before IVIG therapy were significantly higher in group 2 than group 3 and 4. Serum homocysteine and TNF-α levels were highest in group 2 before IVIG therapy. In the acute KD patients, serum homocysteine levels correlated significantly with TNF-α levels. Conclusion:The increased serum homocysteine levels in the acute stage increase the susceptibility to coronary arterial lesions in KD. TNF-α may also play an important role in the formation of coronary arterial lesions in KD

Sustained activation of neutrophils in the course of Kawasaki disease: an association with matrix metalloproteinases

Kawasaki disease (KD) is an acute febrile syndrome of childhood, characterized by vasculitis of the medium-sized arteries. White blood cell counts and the inflammatory parameter C-reactive protein (CRP) are known to be elevated in the acute phase of the disease. In this study we investigated the course of inflammatory cell type-specific parameters in KD over a longer period of time. Plasma levels of human neutrophil elastase (HNE), matrix metalloproteinases-2 and -9 (MMP2, MMP9), and neutrophil gelatinase-associated lipocalin (NGAL), macrophage neopterin and CRP were measured. Plasma samples were collected in the acute, subacute and early convalescent stage, and three months after the onset of disease. Median CRP and neopterin normalized within two weeks. In contrast, six weeks and three months after onset of disease, levels of HNE were still elevated, with median values of 163 ng/ml and 156 ng/ml, respectively (control children median < 50 ng/ml; for all time-points P < 0.0001). Values of NGAL correlated with the levels of HNE (r = 0.39, P = 0.013). These results demonstrate a longer state of neutrophil activation in KD than was previously assumed. The potential relationship between this prolonged neutrophil activation, coronary artery lesion formation and their persistence, as well as the risk of premature atherosclerosis warrants further evaluation.

Endothelial nitric oxide synthase gene transfer restores endothelium–dependent relaxations and attenuates lesion formation in carotid arteries in apolipoprotein E–deficient mice

Nitric oxide (NO) and monocyte chemoattractant protein-1 (MCP-1) exert partly opposing effects in vascular biology. NO plays pleiotropic vasoprotective roles including vasodilation and inhibition of platelet aggregation, smooth muscle cell proliferation, and endothelial monocyte adhesion, the last effect being mediated by MCP-1 downregulation. Early stages of arteriosclerosis are associated with reduced NO bioactivity and enhanced MCP-1 expression. We have evaluated adenovirus-mediated gene transfer of human endothelial NO synthase (eNOS) and of a N-terminal deletion (8ND) mutant of the MCP-1 gene that acts as a MCP-1 inhibitor in arteriosclerosis-prone, apolipoprotein E-deficient (ApoE(-/-)) mice. Endothelium-dependent relaxations were impaired in carotid arteries instilled with a noncoding adenoviral vector but were restored by eNOS gene transfer (p < 0.01). A perivascular collar was placed around the common carotid artery to accelerate lesion formation. eNOS gene transfer reduced lesion surface areas, intima/media ratios, and macrophage contents in the media at 5-week follow-up (p < 0.05). In contrast, 8ND-MCP-1 gene transfer did not prevent lesion formation. In conclusion, eNOS gene transfer restores endothelium-dependent vasodilation and inhibits lesion formation in ApoE(-/-) mouse carotids. Further studies are needed to assess whether vasoprotection is maintained at later disease stages and to evaluate the long-term efficacy of eNOS gene therapy for primary arteriosclerosis.

Intron Retention Generates a Novel Id3 Isoform That Inhibits Vascular Lesion Formation

The expression of intron-containing messages has been shown to occur in a variety of diseases including lactic acidosis, Cowden Syndrome, and several cancers. However, it is unknown whether these intron-containing messages result in protein production in vivo. Indeed, intron-containing RNAs are typically retained in the nucleus, targeted for degradation, or are repressed translationally. Here, we show that during vascular lesion formation in rats, an alternative isoform of the helix-loop-helix transcription factor Id3 (Id3a) generated by intron retention is abundantly expressed. We demonstrate that Id3 is expressed early in lesion formation when the proliferative index of the neointima is highest and that Id3 promotes smooth muscle cell (SMC) proliferation and S-phase entry and inhibits transcription of the cell-cycle inhibitor p21(Cip1). Using an Id3a-specific antibody developed by our laboratory, we show that Id3a protein is induced during vascular lesion formation and that Id3a expression peaks late when the proliferative index is low or declining and extensive apoptosis is observed. Furthermore, Id3a fails to promote SMC growth and S-phase entry or to inhibit p21(Cip1) promoter transactivation. In contrast, Id3a stimulates SMC apoptosis and inhibits endogenous Id3 production. Adenoviral delivery of Id3a inhibited lesion formation in balloon-injured rat carotid arteries in vivo. These data describe a novel feedback loop whereby intron retention generates an Id3 isoform that acts to limit SMC growth during vascular lesion formation, providing the first evidence that regulated intron retention can modulate a pathologic process in vivo.

Lipoprotein-associated phospholipase A2 (platelet-activating factor acetylhydrolase) and cardiovascular disease.

Plasma lipoproteins carry a number of highly active enzymes in the circulation. One of these is lipoprotein-associated phospholipase A(2) (Lp-PLA(2)), also known as platelet-activating factor acetylhydrolase. This review addresses the molecular properties of Lp-PLA(2), the controversy surrounding its role in atherosclerosis and the regulation of its plasma levels in humans. Recent reports indicate that the enzyme Lp-PLA(2) found in both LDL and HDL may be independently regulated in these lipoprotein subclasses and have distinct roles in atherogenesis. Seminal findings establishing the response-to-retention hypothesis of atherosclerosis support further the potentially damaging role that in-situ release of LDL-associated oxidative products by Lp-PLA(2) may have in the formation of arterial wall lesions. In the mouse, where Lp-PLA(2) circulates mainly bound to HDL, overexpression leads to reduced atherosclerosis, raising the possibility that the enzyme in HDL may have a protective role. Further evidence for a potential protective role is seen in studies of partial or complete deficiency of the enzyme. In the more general setting of population studies, however, it is clear that Lp-PLA(2) is a positive risk factor for coronary disease and measurements of its mass may contribute to the prediction of coronary heart disease risk, especially in individuals with low LDL cholesterol levels. Lp-PLA(2) is an enzyme with potentially multiple risks in atherosclerosis. In humans the weight of evidence suggests that it is a positive risk factor for coronary heart disease - an observation commensurate with its position in the direct pathological sequence leading from formation of oxidized LDL in the artery wall to cellular dysfunction and formation of lesions.

Decreased Reendothelialization and Increased Neointima Formation With Endostatin Overexpression in a Mouse Model of Arterial Injury

Impaired endothelial regeneration contributes to arterial lesion formation. Endostatin is a specific inhibitor of endothelial cell growth and induces endothelial cell apoptosis. We examined the effect of endostatin overexpression on reendothelialization and neointima formation in a mouse model of arterial injury. Mice underwent femoral arterial denudation and received recombinant adenovirus, expressing either murine endostatin (n=19) or control adenoviral vector (n=12), by jugular vein injection. Endostatin gene transfer resulted in high serum levels of endostatin. Strong adenoviral gene expression of beta-galactosidase-expressing control vector was detected in liver tissue and was absent in the injured arterial wall at 1 week. Deposits of endostatin protein were detected along the denuded arterial wall and were not seen in the noninjured contralateral artery at 1 week. Endostatin deposits were also absent in the injured artery of control vector-treated animals. Overexpression of endostatin led to decreased reendothelialization and increased apoptosis of luminal endothelial cells 2 and 4 weeks after arterial injury (P<0.05). In addition, endostatin overexpression resulted in increased neointima formation (P<0.05). Endothelial apoptosis and neointima area correlated positively with endostatin serum levels, whereas the degree of reendothelialization correlated negatively with endostatin serum levels (P<0.05). Furthermore, poor reendothelialization correlated with increased neointima formation (P<0.05). In summary, decreased reendothelialization and enhanced endothelial apoptosis, in response to endostatin overexpression, were associated with increased neointima formation. These findings demonstrate that high serum levels of endostatin are capable of inhibiting endothelial regeneration and promoting arterial lesion growth in conditions of endothelial injury.

C-Jun Regulates Vascular Smooth Muscle Cell Growth and Neointima Formation after Arterial Injury: INHIBITION BY A NOVEL DNA ENZYME TARGETING c-Jun

Neointima formation is a characteristic feature of common vascular pathologies, such as atherosclerosis and post-angioplasty restenosis, and involves smooth muscle cell proliferation. Determination of whether the bZIP transcription factor c-Jun plays a direct regulatory role in arterial lesion formation, or indeed in other disease, has been hampered by the lack of a potent and specific pharmacological inhibitor. c-Jun is poorly expressed in the uninjured artery wall and transiently induced following arterial injury in animal models. Here we generated a gene-specific DNAzyme-targeting c-Jun. We show that c-Jun protein is expressed in human atherosclerotic lesions. Dz13, a catalytically active c-Jun DNAzyme, cleaved c-Jun RNA and inhibited inducible c-Jun protein expression in vascular smooth muscle cells. Dz13 blocked vascular smooth muscle cell proliferation with potency exceeding its exact non-catalytic antisense oligodeoxynucleotide equivalent. Moreover, Dz13 abrogated smooth muscle cell repair following scraping injury in vitro and intimal thickening in injured rat carotid arteries in vivo. These studies demonstrate the positive influence on neointima formation by c-Jun and the therapeutic potential of a DNAzyme controlling its expression.