Expression of interleukin-1 beta and interleukin-1 receptor antagonist in oxLDL-treated human aortic smooth muscle cells and in the neointima of cholesterol-fed endothelia-denuded rabbits

High glucose levels accelerate atherosclerosis via NLRP3-IL/ MAPK/NF-κB-related inflammation pathways

BACKGROUND

As a chronic inflammatory disease, diabetes mellitus (DM) contributes to the development of atherosclerosis (AS). However, how the NLRP3 inflammasome participates in diabetes-related AS remains unclear. Therefore, this study aimed to elucidate the mechanism through which NLRP3 uses high glucose (HG) levels to promote AS.

METHODS

Serum and coronary artery tissues were collected from coronary artery disease (CAD) patients with and without DM, respectively. The expression of NLRP3 was detected, and the effects of this inflammasome on diabetes-associated AS were evaluated using streptozotocin (STZ)-induced diabetic apoE-/- mice injected with Adenovirus-mediated NLRP3 interference (Ad-NLRP3i). To elucidate the potential mechanism involved, ox-LDL-irritated human aortic smooth muscle cells were divided into the control, high-glucose, Si-NC, and Si-NLRP3 groups to observe the changes induced by downregulating NLRP3 expression. For up-regulating NLRP3, control and plasmid contained NLRP3 were used. TNF-α, IL-1β, IL-6, IL-18, phosphorylated and total p38, JNK, p65, and IκBα expression levels were detected following the downregulation or upregulation of NLRP3 expression.

RESULTS

Patients with comorbid CAD and DM showed higher serum levels and expression of NLRP3 in the coronary artery than those with only CAD. Moreover, mice in the Ad-NLRP3i group showed markedly smaller and more stable atherosclerotic lesions compared to those in other DM groups. These mice had decreased inflammatory cytokine production and improved glucose tolerance, which demonstrated the substantial effects of NLRP3 in the progression of diabetes-associated AS. Furthermore, using the siRNA or plasmid to downregulate or upregulate NLRP3 expression in vitro altered cytokines and the MAPK/NF-κB pathway.

CONCLUSIONS

NLRP3 expression was significantly increased under hyperglycemia. Additionally, it accelerated AS by promoting inflammation via the IL/MAPK/NF-κB pathway.

Interactions between PCSK9 and NLRP3 inflammasome signaling in atherosclerosis

Atherosclerosis is an early pathological basis of numerous cardiovascular events that result in death or disability. Recent studies have described PCSK9 as a novel target for the treatment of atherosclerosis; PCSK9 is capable of degrading LDLR on the surface of hepatocytes through the regulation of lipid metabolism, and it can function as a novel inflammatory modulator in atherosclerosis. Inflammasomes are important intracellular multiprotein complexes that promote the inflammatory response in atherosclerosis. Among inflammasomes, the NLRP3 inflammasome is particularly notable because of its important role in the development of atherosclerotic disease. After activation, NLRP3 forms a complex with ASC and pro-caspase-1, converting pro-caspase-1 into activated caspase-1, which may trigger the release of IL-1β and IL-18 and contribute to the inflammatory response. Several recent studies have indicated that there may be interactions between PCSK9 and the NLRP3 inflammasome, which may contribute to the inflammatory response that drives atherosclerosis development and progression. On the one hand, the NLRP3 inflammasome plays an important role via IL-1β in regulating PCSK9 secretion. On the other hand, PCSK9 regulates caspase-1-dependent pyroptosis by initiating mtDNA damage and activating NLRP3 inflammasome signaling. This paper reviews the mechanisms underlying PCSK9 and NLRP3 inflammasome activation in the context of atherosclerosis. Furthermore, we describe the current understanding of the specific molecular mechanism underlying the interactions between PCSK9 and NLRP3 inflammasome signaling as well as the drug repositioning events that influence vascular cells and exert beneficial antiatherosclerotic effects. This review may provide a new therapeutic direction for the effective prevention and treatment of atherosclerosis in the clinic.

LncRNA H19 Mitigates Oxidized Low-Density Lipoprotein Induced Pyroptosis via Caspase-1 in Raw 264.7 Cells

Atherosclerosis (AS) is mainly characterized by the activation of inflammatory cells and chronic inflammatory responses after cell injury. Pyroptosis is a form of programmed cell death (PCD) accompanied by the release of inflammatory factors. Many studies have shown that pyroptosis plays an important role in AS. Increasing evidence also indicates that long non-coding RNA H19 (lncRNA H19) involved in AS. However, whether the role of lncRNA H19 in AS is related to pyroptosis and the underlying mechanisms are largely unknown. In this study, we found that oxidized low-density lipoprotein (ox-LDL) induced pyroptosis and decreased the expression of lncRNA H19 in Raw 264.7 cells. Besides, silencing endogenous lncRNA H19 increased inflammatory responses and pyroptosis while exogenous overexpression of lncRNA H19 reversed this effect. Notably, we identified that the inhibitor of caspase-1 (XV-765) completely abrogated the silencing endogenous lncRNA H19 mediated pyroptosis. In addition, we found that lncRNA H19 inhibited ox-LDL-induced activation of nuclear factor-kappa B (NF-κB), mitochondrial dysfunction, and reduced the production of reactive oxygen species (ROS). Moreover, VX-765 impaired the silencing endogenous lncRNA H19 mediated pyroptosis. Overall, these findings indicated that lncRNA H19 may play an important role in pyroptosis and may serve as a potential therapeutic target for AS.

A Novel Relative High-Density Lipoprotein Index to Predict the Structural Changes in High-Density Lipoprotein and Its Ability to Inhibit Endothelial-Mesenchymal Transition

Therapeutic elevation of high-density lipoprotein (HDL) is thought to minimize atherogenesis in subjects with dyslipidemia. However, this is not the case in clinical practice. The function of HDL is not determined by its concentration in the plasma but by its specific structural components. We previously identified an index for the prediction of HDL functionality, relative HDL (rHDL) index, and preliminarily explored that dysfunctional HDL (rHDL index value > 2) failed to rescue the damage to endothelial progenitor cells (EPCs). To confirm the effectiveness of the rHDL index for predicting HDL functions, here we evaluated the effects of HDL from patients with different rHDL index values on the endothelial–mesenchymal transition (EndoMT) of EPCs. We also analyzed the lipid species in HDL with different rHDL index values and investigated the structural differences that affect HDL functions. The results indicate that HDL from healthy adults and subjects with an rHDL index value < 2 protected transforming growth factor (TGF)-β1-stimulated EndoMT by modulating Smad2/3 and Snail activation. HDL from subjects with an rHDL index value > 2 failed to restore the functionality of TGF-β1-treated EPCs. Lipidomic analysis demonstrated that HDL with different rHDL index values may differ in the composition of triglycerides, phosphatidylcholine, and phosphatidylinositol. In conclusion, we confirmed the applicability of the rHDL index value to predict HDL function and found structural differences that may affect the function of HDL, which warrants further in-depth studies.

The SGLT2 inhibitor Empagliflozin attenuates interleukin-17A-induced human aortic smooth muscle cell proliferation and migration by targeting TRAF3IP2/ROS/NLRP3/Caspase-1-dependent IL-1β and IL-18 secretion

Chronic inflammation and persistent oxidative stress contribute to the development and progression of vascular proliferative diseases. We hypothesized that the proinflammatory cytokine interleukin (IL)-17A induces oxidative stress and amplifies inflammatory signaling in human aortic smooth muscle cells (SMC) via TRAF3IP2-mediated NLRP3/caspase-1-dependent mitogenic and migratory proinflammatory cytokines IL-1β and IL-18. Further, we hypothesized that these maladaptive changes are prevented by empagliflozin (EMPA), an SGLT2 (Sodium/Glucose Cotransporter 2) inhibitor. Supporting our hypotheses, exposure of cultured SMC to IL-17A promoted proliferation and migration via TRAF3IP2, TRAF3IP2-dependent superoxide and hydrogen peroxide production, NLRP3 expression, caspase-1 activation, and IL-1β and IL-18 secretion. Furthermore, NLRP3 knockdown, caspase-1 inhibition, and pretreatment with IL-1β and IL-18 neutralizing antibodies and IL-18BP, each attenuated IL-17A-induced SMC migration and proliferation. Importantly, SMC express SGLT2, and pre-treatment with EMPA attenuated IL-17A/TRAF3IP2-dependent oxidative stress, NLRP3 expression, caspase-1 activation, IL-1β and IL-18 secretion, and SMC proliferation and migration. Importantly, silencing SGLT2 attenuated EMPA-mediated inhibition of IL-17A-induced cytokine secretion and SMC proliferation and migration. EMPA exerted these beneficial antioxidant, anti-inflammatory, anti-mitogenic and anti-migratory effects under normal glucose conditions and without inducing cell death. These results suggest the therapeutic potential of EMPA in vascular proliferative diseases.

Enhancer of zeste homolog 2 participates in the process of atherosclerosis by modulating microRNA-139-5p methylation and signal transducer and activator of transcription 1 expression

Atherosclerosis (AS) is the main cause of coronary heart disease, in which enhancer of zeste homolog 2 (EZH2) has been implied to participate in this process. Thus, this work proposed to explore the effect of EZH2 on AS from microRNA-139-5p (miR-139-5p)/signal transducer and activator of transcription 1 (STAT1) axis. EZH2, miR-139-5p, and STAT1 expression in arterial tissues of AS patients were detected. Human arterial smooth muscle cells (HASMCs) induced with oxidized low-density lipoprotein (ox-LDL) and the mice fed with high fat diet were treated with silenced EZH2 or upregulated miR-139-5p to explore their roles in proliferation and apoptosis of HASMCs, together with inflammation response and oxidative stress of mice. Chromatin immunoprecipitation experiment was applied to verify the regulatory effect of EZH2 on miR-139-5p through methylation of H3K27me3. The targeting relationship between miR-139-5p and STAT1 was verified by online website and luciferase activity assay. Reduced miR-139-5p and overexpressed EHZ2 and STAT1 were found in AS. Silenced EZH2 or elevated miR-139-5p decreased the production of cholesterol and inhibited inflammation reaction in serum of mice with AS. Silenced EZH2 or elevated miR-139-5p facilitated proliferation and restrained apoptosis of ox-LDL-treated HASMCs, and restrained oxidative stress and cell apoptosis in arterial tissues of AS mice. EZH2 regulated miR-139-5p through H3K27me3, and miR-139-5p targeted STAT1. miR-139-5p silencing antagonized the effects of EZH2 down-regulation on AS. This study manifests that down-regulated EZH2 or elevated miR-139-5p inhibits ox-LDL-induced HASMCs apoptosis, plaque formation, and inflammatory response in AS mice, which may be related to down-regulated STAT1.

Interleukin‑37 is increased in peripheral blood mononuclear cells of coronary heart disease patients and inhibits the inflammatory reaction

It has been universally acknowledged that interleukin-37 (IL-37) has an immunosuppressive effect on various inflammatory disorders. However, whether IL-37 participates in the acute inflammation associated with coronary heart disease (CHD) has not yet been clarified. In the present study, the association between the serum levels of IL-37 and the clinical indexes of CHD were analysed. In addition, the anti-inflammatory effects of IL-37 on peripheral blood mononuclear cells (PBMCs) were studied in CHD patients. PBMCs from 46 healthy controls (HCs) and 92 CHD patients were cultured in vitro and stimulated using the recombinant IL-37 protein. The protein levels, as well as the mRNA expression of inflammatory cytokines (TNF-α, IL-1β, IL-6, and IL-17) were analysed by enzyme-linked immunosorbent assay (ELISA) and real-time polymerase chain reaction (RT-PCR). Spearman's correlation test was performed to examine the association between the serum level of IL-37 and the levels of pro-inflammatory cytokines, certain clinical indexes, and disease activity during CHD. Compared to the HCs, the CHD patients, especially those with acute myocardial infarction, exhibited higher levels of IL-37 in their PBMCs and sera. Serum levels of IL-37 were associated with the levels of IL-17, IL-6, and TNF-α, and clinical indexes such as the left ventricular ejection fraction (LVEF), amino-N-terminal pro-plasma brain natriuretic peptide (NT-proBNP) levels, and cardiac troponin T (cTnT) levels in CHD patients. Compared to the HC group, the production of inflammatory cytokines such as IL-17, IL-6, TNF-α, and IL-1β increased in the PBMCs of CHD patients and significantly decreased after the stimulation of the cells with recombinant IL-37. The IL-37 levels in CHD patients were high, and were correlated with the levels of CHD-related pro-inflammatory cytokines and disease activity. Notably, the expression of CHD-related pro-inflammatory cytokines in the PBMCs of CHD patients decreased following the stimulation of the cells with recombinant IL-37, indicating that IL-37 exerts anti-inflammatory effects during CHD.

NLRP3 inflammasome and lipid metabolism analysis based on UPLC-Q-TOF-MS in gouty nephropathy

To determine the differences in plasma metabolism between healthy patients and patients with hyperuricaemia and gouty nephropathy, the present study identified differentially expressed metabolites associated with gouty nephropathy. Furthermore, the NLRP3 inflammasome signalling pathway in gouty nephropathy was explored, and the mechanism of hyperuricaemia-induced renal damage. Adult male patients examined between July 2016 and June 2017 were selected as the patient cohort for the present study from the Affiliated Bao'an Hospital of Shenzhen, Southern Medical University (Shenzhen, China). These patients were divided into three groups of 30 patients each: Control, hyperuricaemia and gouty nephropathy groups. The expression levels of NLRP3, ASC and caspase-1 mRNA and protein were detected in peripheral blood mononuclear cells, and the plasma levels of IL-1β and IL-18. Ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry was used to determine differential levels of metabolites between patients from different groups, in order to identify potential biomarkers. The expression of the NLRP3 inflammasome in peripheral blood mononuclear cells, and the levels of IL-1β and IL-18 in the plasma were increased in the gouty nephropathy group compared with the control and hyperuricaemia groups. In addition, 46 metabolites were identified as potential plasma metabolic biomarkers that were able to distinguish gouty nephropathy from hyperuricaemia. The majority of these metabolites were involved in lipid metabolism, in particular the activity of phospholipase A2 and β-oxidation. These data indicated that lipid metabolism and the NLRP3 inflammasome serve a pivotal role in gouty nephropathy. In addition, the results suggested that lipids may mediate the progression of gouty nephropathy through the activity of phospholipase A2, β-oxidation and activation of the NLRP3 inflammasome.

Dysfunctional high density lipoprotein failed to rescue the function of oxidized low density lipoprotein-treated endothelial progenitor cells: a novel index for the prediction of HDL functionality

Lipid metabolic disorders play critical roles in atherogenesis. Traditionally, it has been suggested that reduced high density lipoprotein (HDL) levels might be an important morbidity indicator for cardiovascular diseases. Therefore, it has been argued that therapeutically raising HDL levels may reduce atherogenesis in patients with dyslipidemia. However, recent clinical trials to elevate serum HDL levels by pharmacologic approaches failed to demonstrate clinical efficacy. Thus, to investigate the functionality of HDL and to explore the possible clinical relevance as well as to define an effective indicator that can represent HDL function may provide another key and reference to disclose the clinical treatment of dyslipidemia. We analyzed the association between the data of dichlorofluorescein assay (assay the functionality of HDL), the effect of HDL on oxidized low density lipoprotein (oxLDL)-stimulated endothelial progenitor cells (EPCs) in vitro, levels of circulating EPCs, and ex vitro EPC colony forming units of each case, we defined the indicator (relative HDL index (RHDL index) = dichlorofluorescein assay result of each subject/dichlorofluorescein assay reading of our young healthy controls) that may represent functionality of HDL. HDL from healthy adults protected oxLDL-treated EPCs by modulating p38 mitogen-activated protein kinase and Rho activation and by promoting nitric oxide production. HDL from subject with RHDL index ≧2 also failed to restore the functionality of oxLDL-treated EPCs via cell-signaling pathways in vitro. The RHDL index significantly correlated with patients' circulating EPC number or EPC colony forming units ex vivo. In conclusions, we explored the RHDL index as a score to predict a patient's EPC functions in vivo and ex vitro.

Lysosomal membrane permeabilization causes secretion of IL-1β in human vascular smooth muscle cells

Objective

IL-1β secretion by the inflammasome is strictly controlled and requires two sequential signals: a priming signal and an activating signal. Lysosomal membrane permeabilization (LMP) plays a critical role in the regulation of NLRP3 inflammasome, and generally acts as an activating signal. However, the role of LMP controlling NLRP3 inflammasome activation in human vascular smooth muscle cells (hVSMCs) is not well defined.

Methods

LMP was induced in hVSMCs by Leu-Leu-O-methyl ester. Cathepsin B was inhibited by CA-074 Me. Cytokine release, mRNA, and protein were quantified by enzyme-linked immunosorbent assay, quantitative PCR, and Western blot, respectively. NF-κB activity was analyzed by immunostaining of the NF-κB p65 nuclear translocation and using the dual-luciferase reporter assay system.

Results

LMP had both priming and activating roles, causing an upregulation of proIL-1β and NLRP3 and the secretion of mature IL-1β from unprimed hVSMCs. LMP activated the canonical NF-κB pathway. The priming effect of LMP was inhibited by CA-074 Me, indicating an upstream role of cathepsin B.

Conclusions

These data support a novel role of LMP as a single stimulus for the secretion of IL-1β from hVSMCs, implying the possibility that hVSMCs are an important initiator of the sterile inflammatory response caused by lysosomal disintegration.

Cysteine Protease Cathepsins in Atherosclerotic Cardiovascular Diseases

Atherosclerotic cardiovascular disease (ASCVD) is an inflammatory disease characterized by extensive arterial wall matrix protein degradation. Cysteine protease cathepsins play a pivotal role in extracellular matrix (ECM) remodeling and have been implicated in the development and progression of atherosclerosis-based cardiovascular diseases. An imbalance in expression between cathepsins (such as cathepsins S, K, L, C) and their inhibitor cystatin C may favor proteolysis of ECM in the pathogenesis of cardiovascular disease such as atherosclerosis, aneurysm formation, restenosis, and neovascularization. New insights into cathepsin functions have been made possible by the generation of knock-out mice and by the application of specific inhibitors. Inflammatory cytokines regulate the expression and activities of cathepsins in cultured vascular cells and macrophages. In addition, evaluations of the possibility of cathepsins as a diagnostic tool revealed that the circulating levels of cathepsin S, K, and L, and their endogenous inhibitor cystatin C could be promising biomarkers in the diagnosis of coronary artery disease, aneurysm, adiposity, peripheral arterial disease, and coronary artery calcification. In this review, we summarize the available information regarding the mechanistic contributions of cathepsins to ASCVD.

The Role of Lipid Biomarkers in Major Depression

In the UK, the lifetime-documented prevalence of major depressive disorder (MDD) is currently 10%. Despite its increasing prevalence and devastating impact on quality of life, the pathophysiological mechanisms underpinning MDD remain to be fully elucidated. Current theories of neurobiological components remain incomplete and protein-centric, rendering pharmacological treatment options suboptimal. In this review, we highlight the pivotal role of lipids in intra- and inter-neuronal functioning, emphasising the potential use of lipids as biomarkers for MDD. The latter has significant implications for improving our understanding of MDD at the cellular and circuit level. There is particular focus on cholesterol (high and low density lipoprotein), omega-3, and omega-6 polyunsaturated fatty acids due to established evidence in the literature of a link between atherosclerotic disease and major depression. We argue that there is significant potential scope for the use of such peripheral biomarkers in the diagnosis, stratification and treatment of MDD.

Pravastatin and Clopidogrel Combined Inhibit Intimal Hyperplasia in a Rat Carotid Endarterectomy Model

Intimal hyperplasia, resulting from a complex cascade of events involving platelets, leukocytes, and smooth muscle cells, may be inhibited by the HMG-CoA reductase inhibitor pravastatin, which demonstrates inhibition of platelet activity and leukocyte adhesion and may be associated with inhibition of vascular smooth muscle cell proliferation and migration. Clopidogrel, an adenosine diphosphate (ADP) receptor inhibitor, was shown to decrease platelet activity and aggregation but not intimal hyperplasia (IH). We postulated that the combination of both pravastatin and clopidogrel would significantly decrease IH in a rat carotid endarterectomy model. Male Sprague-Dawley rats (n = 18) divided by treatment regimen underwent treatment for 2 weeks both before and after an open carotid endarterectomy. Serum collected at the time of harvest was measured for C-reactive protein (CRP), platelet activity, and total serum cholesterol; carotid arteries were removed and processed for IH determination. Control rats (n = 7) received oral vehicle daily before and following endarterectomy. Pravastatin-alone rats (n = 6) received oral pravastatin (10 mg/kg/day) before and after endarterectomy. Pravastatin plus clopidogrel rats (n = 5) received oral pravastatin (10 mg/kg/day) plus a preendarterectomy bolus of oral clopidogrel (4.3 mg/kg) before endarterectomy and resumed pravastatin (10 mg/kg/day) plus oral clopidogrel (1 mg/kg/day) postendarterectomy. Pravastatin alone and pravastatin plus clopidogrel significantly decreased CRP compared to controls (120.2 ±11.2 and 134.1 ±9.9 vs 191.1 ±9.2 µg/mL, respectively p = 0.003 and p = 0.0024). CRP levels were not different between pravastatin alone and pravastatin plus clopidogrel (p = 0.35). Platelet activity was significantly decreased by pravastatin alone and pravastatin plus clopidogrel in comparison to controls (7.3 ±2.2 and 6.6 ±2.8 vs 19.2 ±6.1 platelet reactive units (PRU), respectively p = 0.048 and p = 0.045). No significant difference was noted in platelet activity between pravastatin alone and pravastatin plus clopidogrel (p = 0.89). Pravastatin plus clopidogrel significantly reduced serum cholesterol compared to control and pravastatin alone (84.0 ±6.6 vs 110.4 ±7.4 and 117.0 ±8.8 mg/dL, respectively p = 0.03 and p = 0.01). Pravastatin alone did not decrease serum cholesterol compared to controls (p = 0.54). IH was not reduced by pravastatin alone compared to controls (p = 0.61) but was significantly decreased by pravastatin plus clopidogrel in comparison to control and pravastatin alone (3.0 ±1.1 vs 46.3 ±13.7 and 37.4 ±14.6% luminal stenosis, respectively p = 0.01 and p = 0.05). Pravastatin plus clopidogrel significantly decreased CRP, platelet activity, total serum cholesterol, and IH while pravastatin alone decreased only CRP and platelet activity. Intimal hyperplasia reduction may therefore be dependent on other contributors, possibly growth factors, cytokines, and oxidative stress. The combination of pravastatin plus clopidogrel may have synergistic or even additional inhibitory effects on IH. Pravastatin plus clopidogrel was effective in decreasing IH in a rat carotid endarterectomy model and may prove a useful therapy for IH reduction in the clinical setting.

Cathepsin S Activity Controls Injury-Related Vascular Repair in Mice via the TLR2-Mediated p38MAPK and PI3K-Akt/p-HDAC6 Signaling Pathway

Supplemental Digital Content is available in the text.

Objective—

Cathepsin S (CatS) participates in atherogenesis through several putative mechanisms. The ability of cathepsins to modify histone tail is likely to contribute to stem cell development. Histone deacetylase 6 (HDAC6) is required in modulating the proliferation and migration of various types of cancer cells. Here, we investigated the cross talk between CatS and HADC6 in injury-related vascular repair in mice.

Approach and Results—

Ligation injury to the carotid artery in mice increased the CatS expression, and CatS-deficient mice showed reduced neointimal formation in injured arteries. CatS deficiency decreased the phosphorylation levels of p38 mitogen-activated protein kinase, Akt, and HDAC6 and toll-like receptor 2 expression in ligated arteries. The genetic or pharmacological inhibition of CatS also alleviated the increased phosphorylation of p38 mitogen-activated protein kinase, Akt, and HDAC6 induced by platelet-derived growth factor BB in cultured vascular smooth muscle cells (VSMCs), and p38 mitogen-activated protein kinase inhibition and Akt inhibition decreased the phospho-HDAC6 levels. Moreover, CatS inhibition caused decrease in the levels of the HDAC6 activity in VSMCs in response to platelet-derived growth factor BB. The HDAC6 inhibitor tubastatin A downregulated platelet-derived growth factor–induced VSMC proliferation and migration, whereas HDAC6 overexpression exerted the opposite effect. Tubastatin A also decreased the intimal VSMC proliferation and neointimal hyperplasia in response to injury. Toll-like receptor 2 silencing decreased the phosphorylation levels of p38 mitogen-activated protein kinase, Akt, and HDAC6 and VSMC migration and proliferation.

Conclusions—

This is the first report detailing cross-interaction between toll-like receptor 2–mediated CatS and HDAC6 during injury-related vascular repair. These data suggest that CatS/HDAC6 could be a potential therapeutic target for the control of vascular diseases that are involved in neointimal lesion formation.

Amphiphilic macromolecule nanoassemblies suppress smooth muscle cell proliferation and platelet adhesion

While the development of second- and third-generation drug-eluting stents (DES) have significantly improved patient outcomes by reducing smooth muscle cell (SMC) proliferation, DES have also been associated with an increased risk of late-stent thrombosis due to delayed re-endothelialization and hypersensitivity reactions from the drug-polymer coating. Furthermore, DES anti-proliferative agents do not counteract the upstream oxidative stress that triggers the SMC proliferation cascade. In this study, we investigate biocompatible amphiphilic macromolecules (AMs) that address high oxidative lipoprotein microenvironments by competitively binding oxidized lipid receptors and suppressing SMC proliferation with minimal cytotoxicity. To determine the influence of nanoscale assembly on proliferation, micelles and nanoparticles were fabricated from AM unimers containing a phosphonate or carboxylate end-group, a sugar-based hydrophobic domain, and a hydrophilic poly(ethylene glycol) domain. The results indicate that when SMCs are exposed to high levels of oxidized lipid stimuli, nanotherapeutics inhibit lipid uptake, downregulate scavenger receptor expression, and attenuate scavenger receptor gene transcription in SMCs, and thus significantly suppress proliferation. Although both functional end-groups were similarly efficacious, nanoparticles suppressed oxidized lipid uptake and scavenger receptor expression more effectively compared to micelles, indicating the relative importance of formulation characteristics (e.g., higher localized AM concentrations and nanotherapeutic stability) in scavenger receptor binding as compared to AM end-group functionality. Furthermore, AM coatings significantly prevented platelet adhesion to metal, demonstrating its potential as an anti-platelet therapy to treat thrombosis. Thus, AM micelles and NPs can effectively repress early stage SMC proliferation and thrombosis through non-cytotoxic mechanisms, highlighting the promise of nanomedicine for next-generation cardiovascular therapeutics.

Epigallocatechin gallate attenuates proliferation and oxidative stress in human vascular smooth muscle cells induced by interleukin-1β via heme oxygenase-1

Proliferation of vascular smooth muscle cells (VSMCs) triggered by inflammatory stimuli and oxidative stress contributes importantly to atherogenesis. The association of green tea consumption with cardiovascular protection has been well documented in epidemiological observations, however, the underlying mechanisms remain unclear. This study aimed to elucidate the effects of the most active green tea catechin derivative, (−)-epigallocatechin-3-gallate (EGCG), in human aortic smooth muscle cells (HASMCs), focusing particularly on the role of a potent anti-inflammatory and antioxidative enzyme heme oxygenase-1 (HO-1). We found that pretreatment of EGCG dose- and time-dependently induced HO-1 protein levels in HASMCs. EGCG inhibited interleukin- (IL-)1β-induced HASMC proliferation and oxidative stress in a dose-dependent manner. The HO-1 inducer CoPPIX decreased IL-1β-induced cell proliferation, whereas the HO-1 enzyme inhibitor ZnPPIX significantly reversed EGCG-caused growth inhibition in IL-1β-treated HASMCs. At the molecular level, EGCG treatment significantly activated nuclear factor erythroid-2-related factor (Nrf2) transcription activities. These results suggest that EGCG might serve as a complementary and alternative medicine in the treatment of these pathologies by inducing HO-1 expression and subsequently decreasing VSMC proliferation.

Moderate to High Concentrations of High-Density Lipoprotein From Healthy Subjects Paradoxically Impair Human Endothelial Progenitor Cells and Related Angiogenesis by Activating Rho-Associated Kinase Pathways

Objective—

Recent clinical evidence has failed to demonstrate the benefits of elevation of serum high-density lipoprotein (HDL), suggesting potential loss of protective effects of HDL at high concentrations. This study aimed to investigate the concentration-related effects of HDL on in vitro and in vivo functions of human endothelial progenitor cells (EPCs) and related angiogenesis.

Methods and Results—

Early and late outgrowth EPCs were generated from human circulating mononuclear cells. Oxidized low-density lipoprotein reduced viability of late outgrowth EPCs, which was reversed dose dependently by HDL. In the absence of oxidized low-density lipoprotein, HDL at low concentrations (5–50 μg/mL, equal to 0.5–5 mg/dL in human) enhanced EPC tube formation by activating phosphatidylinositol-3 kinase/Akt/endothelial NO synthase pathways. Moderate to high concentrations (400–800 μg/mL) of HDL paradoxically enhanced EPC senescence and impaired tube formation by activating Rho-associated kinase (ROCK) and inhibiting phosphatidylinositol-3 kinase/Akt and p38 mitogen-activated protein kinase pathways. Rho-associated kinase inhibitors, either Y27632 or statins, prevented high HDL–induced EPC senescence and improved in vitro tube formation, as well as in vivo capacity of angiogenesis of EPCs.

Conclusion—

While protecting EPCs from the injury of oxidized low-density lipoprotein, moderate to high concentrations of HDL paradoxically impaired EPCs and related angiogenesis in the absence of oxidized low-density lipoprotein by activating Rho-associated kinase pathways, providing mechanistic evidence of potential hazard effects of HDL.

Anti-atherogenic effect of San-Huang-Xie-Xin-Tang, a traditional Chinese medicine, in cultured human aortic smooth muscle cells

AIM OF THE STUDY

San-huang-xie-xin-tang (SHXXT) is a traditional Chinese medicine and it has been shown to have an anti-inflammatory effect. Since inflammation is one of the major mechanisms of atherosclerosis, we aimed to investigate anti-atherosclerotic effect of SHXXT in human aortic smooth muscle cells (HASMCs).

MATERIALS AND METHODS

Human aortic smooth muscle cells (HASMCs) were used in the present study, and rendered atherosclerosis by adding lipopolysaccharides. We first tested the effects of SHXXT on HASMC migration and proliferation as they present the major morphological change of atherosclerosis. We also examined whether SHXXT can influence the production of several biomarkers of inflammation and atherosclerosis including reactive oxygen species (ROS), COX-2, ERK1/2, IL-1β, IL-6, IL-8 and MCP-1.

RESULTS

Using the dimethyl-thiazol-diphenyltetrazoliumbromide (MTT) and wound repair assay, SHXXT was shown to significantly reduce HASMC proliferation and migration, respectively. From the fluorometric assay, SHXXT significantly reduced ROS production. SHXXT down regulated mRNA and protein levels for the COX-2 gene. In addition, phosphorylated ERK1/2 levels were suppressed by SHXXT suggesting HASMC division can be inhibited under pro-inflammatory condition. SHXXT significantly inhibited the production of IL-1β, IL-6, IL-8 and MCP-1 after LPS stimulation.

CONCLUSIONS

Our results indicated that SHXXT can influence several mechanisms involved in atherosclerosis, which suggests that SHXXT may have a therapeutic potential for cardiovascular disease associated with atherosclerosis.

Salvianolic acid B inhibits low-density lipoprotein oxidation and neointimal hyperplasia in endothelium-denuded hypercholesterolaemic rabbits

BACKGROUND

Atherosclerosis and restenosis are inflammatory responses involving free radicals and lipid peroxidation and may be prevented/cured by antioxidant-mediated lipid peroxidation inhibition. Salvianolic acid (Sal B), a water-soluble antioxidant obtained from a Chinese medicinal herb, is believed to have multiple preventive and therapeutic effects against human vascular diseases. In this study the in vitro and in vivo inhibitory effects of Sal B on oxidative stress were determined.

RESULTS

In human aortic endothelial cells (HAECs), Sal B reduced oxidative stress, inhibited low-density lipoprotein (LDL) oxidation and reduced oxidised LDL-induced cytotoxicity. Sal B inhibited Cu(2+) -induced LDL oxidation in vitro (with a potency 16.3 times that of probucol) and attenuated HAEC-mediated LDL oxidation as well as reactive oxygen species (ROS) production. In cholesterol-fed New Zealand White rabbits (with probucol as positive control), Sal B intake reduced Cu(2+) -induced LDL oxidation, lipid deposition in the thoracic aorta, intimal thickness of the aortic arch and thoracic aorta and neointimal formation in the abdominal aorta.

CONCLUSION

The data obtained in this study suggest that Sal B protects HAECs from oxidative injury-mediated cell death via inhibition of ROS production. The antioxidant activity of Sal B may help explain its efficacy in the treatment of vascular diseases.

Serum levels of matrix metalloproteinase-2 as a marker of intimal hyperplasia

BACKGROUND

A primary component in the development of intimal hyperplasia (IH) in response to vascular injury is basement membrane remodeling. Matrix metalloproteinases (MMPs) play a major role in this process by degradation of basement membrane proteins, mainly collagen type IV. Vascular injury initiates an inflammatory cascade with the release of tumor necrosis factor-alpha (TNFalpha), interleukin-1beta (IL-1beta), and C-reactive protein (CRP). We hypothesize serum levels of these elements may serve as biomarkers of the development of IH.

METHODS AND RESULTS

At baseline, 2, 7, 10, and 14 days post-balloon angioplasty of the carotid artery, rat tissue samples were stained with Masson trichrome elastin to examine IH. Intima:media ratios (I:M) increased significantly over time postinjury. Serum samples were collected at the time of tissue sampling, and levels of MMP-2, MMP-9, collagen type IV, TNFalpha, IL-1beta, and CRP were assayed using sandwich enzyme-linked immunosorbent assay (ELISA). MMP-2 serum levels at 7, 10, and 14 days postinjury were significantly elevated compared with baseline. Other elements were not significantly elevated.

CONCLUSION

Early and persistent elevation in the serum levels of MMP-2 may be a useful biomarker of basement membrane remodeling and the presence of IH.

Vascular cells contribute to atherosclerosis by cytokine- and innate-immunity-related inflammatory mechanisms

Cardiovascular diseases are the human diseases with the highest death rate and atherosclerosis is one of the major underlying causes of cardiovascular diseases. Inflammatory and innate immune mechanisms, employing monocytes, innate receptors, innate cytokines, or chemokines are suggested to be involved in atherogenesis. Among the inflammatory pathways the cytokines are central players. Plasma levels of cytokines and related proteins, such as CRP, have been investigated in cardiovascular patients, tissue mRNA expression was analyzed and correlations to vascular diseases established. Consistent with these findings the generation of cytokine-deficient animals has provided direct evidence for a role of cytokines in atherosclerosis. In vitro cell culture experiments further support the suggestion that cytokines and other innate mechanisms contribute to atherogenesis. Among the initiation pathways of atherogenesis are innate mechanisms, such as toll-like-receptors (TLRs), including the endotoxin receptor TLR4. On the other hand, innate cytokines, such as IL-1 or TNF, or even autoimmune triggers may activate the cells. Cytokines potently activate multiple functions relevant to maintain or spoil homeostasis within the vessel wall. Vascular cells, not least smooth muscle cells, can actively contribute to the inflammatory cytokine-dependent network in the blood vessel wall by: (i) production of cytokines; (ii) response to these potent cell activators; and (iii) cytokine-mediated interaction with invading cells, such as monocytes, T-cells, or mast cells. Activation of these pathways results in accumulation of cells and increased LDL- and ECM-deposition which may serve as an 'immunovascular memory' resulting in an ever-growing response to subsequent invasions. Thus, vascular cells may potently contribute to the inflammatory pathways involved in development and acceleration of atherosclerosis.

Effect of hormones on matrix metalloproteinases gene regulation in human aortic smooth muscle cells

BACKGROUND

Postmenopausal women receiving hormone replacement therapy have more adverse outcomes after vascular reconstructions. Estrogen-binding receptors have been identified on vascular smooth muscle cells (VSMCs), indicating that vascular function may be under direct hormonal control. A key group of enzymes involved in vascular remodeling are matrix metalloproteinases (MMPs). Here we studied the effect of estrogen (Est) and progesterone (Prog) on MMP gene expression in human VSMCs.

METHODS AND RESULTS

VSMCs were incubated with Est (5 ng/mL), Prog (50 ng/mL), Est+Prog combination (Est/Prog), and interleukin-1beta (100 U/mL; IL-1beta). Gene array analysis indicated Est+IL-1beta increased the expression of MMP-3. Reverse transcriptase-polymer chain reaction (RT-PCR) analyses revealed MMP-3 mRNA levels were significantly increased by Est/Prog+IL-1beta treatment. However, Western blot and further RT-PCR analyses indicated no change in MMP-3 in response to hormones alone. RT-PCR analyses revealed membrane type 1 (MT1)-MMP mRNA levels, not MMP-2 or tissue inhibitor of MMP (TIMP), were significantly increased by Est/Prog+IL-1beta, and Western blot analyses confirmed a significant increase in MT1-MMP protein in response to Est alone.

CONCLUSION

Estrogen and progesterone affect the MMP pathway of VSMCs via isoform specific mechanisms and may lead to unbalanced MMP regulation. Estrogen up-regulates MT1-MMP without a corresponding increase in TIMP-2, known activator and inhibitor of MMP-2, respectively. Additionally, estrogen up-regulates MMP-3 only in the presence of IL-1beta. This differential regulation, combined with case-specific variations in degree of inflammatory response, may explain why some women receiving exogenous hormone therapy at the time of vascular interventions are more susceptible to complications.

Carvedilol, a pharmacological antioxidant, inhibits neointimal matrix metalloproteinase-2 and -9 in experimental atherosclerosis

Matrix metalloproteinase (MMP) is critical to the progression of atherosclerosis and neointima hyperplasia after vascular injury. We investigated the effects of carvedilol, a pharmacological antioxidant with alpha- and beta-adrenergic blocking activity, on MMP-2 and MMP-9 expression. Vascular injury was induced with the balloon catheters on abdominal aortas of high-cholesterol-fed rabbits. On Day 21, there was significant aortic neointima formation with increased oxidative DNA damage by immunostaining with 8-hydroxy-2'-deoxyguanosine and enhanced MMP-2 and MMP-9 expressions by Western blotting, which were significantly reduced by oral administration of carvedilol (20 mg/kg/day) or probucol (100 mg/kg/day). Vascular expression (by Western blot), activity (by gelatin zymography), and mRNA levels of MMP-2 and MMP-9 were also reduced by carvedilol or probucol. Besides, pretreatment with carvedilol or probucol but not propranolol, a beta-blocker, or prazocin, an alpha-blocker, inhibited tumor necrosis factor-alpha-stimulated expressions and activities of MMP-2 and MMP-9 in human aortic smooth muscle cells. On electrophoretic mobility-shift assay, carvedilol inhibited the binding activities of activator protein-1 and specific protein-1, two major transcription factors for MMP promoter regions. Accordingly, carvedilol, a pharmacological antioxidant, inhibited in vivo and in vitro expression of MMP-2 and MMP-9 properly by modulating the redox-related pathways, suggesting its potential clinical implications.

Steatocholecystitis: the influence of obesity and dietary carbohydrates

INTRODUCTION

We have recently demonstrated that obese and lean mice fed a high fat diet have increased gallbladder wall fat and decreased gallbladder contractility, cholecystosteatosis. Animal and human data also suggest that diets high in refined carbohydrates lead to gallstone formation. However, no data are available on the role of dietary carbohydrates on gallbladder wall fat and inflammation. Therefore, we tested the hypothesis that both obesity and dietary carbohydrates would increase gallbladder fat and cytokines, steatocholecystitis.

METHODS

At 8 wk of age, 47 lean and 22 obese female mice were fed a 45% carbohydrate (CHO) diet while an equal number of lean and obese mice were fed a 75% CHO diet for 4 wk. All mice underwent cholecystectomy, and the gallbladders were snap-frozen. Individual and total lipids were measured by gas chromatography. Interleukin (IL)-1beta, tumor necrosis factor (TNF)-alpha, and IL-6 were measured by enzyme-linked immunosorbent assay. Data were analyzed by analysis of variance and Tukey test.

RESULTS

Gallbladder total fat, triglycerides, and cholesterol were maximum (P < 0.001) in obese mice on the 75% CHO diet. Gallbladder TNF-alpha and IL-1beta as well as serum cholesterol levels showed a similar pattern (P < 0.001). Gallbladder saturated free fatty acids and IL-6 levels were highest (P < 0.001) in obese mice on the 45% CHO diet.

CONCLUSIONS

These data suggest that (1) both obesity and dietary carbohydrates increase gallbladder total fat, triglycerides, cholesterol, TNF-alpha, and IL-1beta and (2) obesity also increases gallbladder free fatty acids and IL-6. Therefore, we conclude that obesity is associated with steatocholecystitis and that a high carbohydrate diet exacerbates this phenomenon.

Superoxide dismutase and catalase inhibit oxidized low-density lipoprotein-induced human aortic smooth muscle cell proliferation: Role of cell-cycle regulation, mitogen-activated protein kinases, and transcription factors

Several antioxidant enzymes, including copper, zinc-superoxide dismutase (Cu, Zn-SOD) and catalase, have been suggested to be protective against the proliferation of vascular smooth muscle cells exposed to oxidative stress. In the present study, we investigated effects of Cu, Zn-SOD and/or catalase on oxLDL-induced proliferation of, and intracellular signaling in, human aortic smooth muscle cells (HASMCs). HASMCs were transfected with adenovirus carrying the human Cu, Zn-SOD gene and/or the human catalase gene. This resulted in a high level of Cu, Zn-SOD and/or catalase overexpression and decreased oxLDL-induced proliferation. Cu, Zn-SOD and/or catalase also arrested cell cycle progression, which was associated with decreased expression of cyclin D1, cyclin E, CDK2, and CDK4 and upregulation of p21(Cip1) and p27(Kip1). Phosphorylation studies on ERK1/2, JNK, and p38, three major subgroups of mitogen activator protein kinases, demonstrated that Cu, Zn-SOD and/or catalase overexpression suppressed ERK1/2 and JNK phosphorylation. Gel-mobility shift analysis showed that oxLDL caused an increase in the DNA binding activity of activator protein-1 (AP-1) and nuclear factor kappaB (NF-kappaB), which was inhibited by Cu, Zn-SOD and/or catalase overexpression. These results provide the first evidence that overexpression of Cu, Zn-SOD and/or catalase in HASMCs attenuates the cell proliferation caused by oxLDL stimulation and that this inhibitory effect is mediated via downregulation of ERK1/2 and JNK phosphorylation and AP-1 and NF-kappaB inactivation. These observations support the feasibility of the increase of Cu, Zn-SOD and/or catalase expression in human smooth muscle cells as a means of protection against oxidant injury.

Nonalcoholic fatty pancreas disease

BACKGROUND

Obesity leads to fat infiltration of multiple organs including the heart, kidneys, and liver. Under conditions of oxidative stress, fat-derived cytokines are released locally and result in an inflammatory process and organ dysfunction. In the liver, fat infiltration has been termed nonalcoholic fatty liver disease, which may lead to nonalcoholic steatohepatitis. No data are available, however, on the influence of obesity on pancreatic fat and cytokines, and nonalcoholic fatty pancreas disease (NAFPD) has not been described. Therefore, we designed a study to determine whether obesity is associated with increased pancreatic fat and cytokines.

MATERIALS AND METHODS

Thirty C57BL/6J lean control and 30 leptin-deficient obese female mice were fed a 15% fat diet for 4 weeks. At 12 weeks of age all animals underwent total pancreatectomy. Pancreata from each strain were pooled for measurement of a) wet and dry weight, b) histologic presence of fat, c) triglycerides, free fatty acids (FFAs), cholesterol, phospholipids, and total fat, and d) interleukin (IL)-1beta and tumor necrosis factor-alpha (TNF-alpha). Data were analyzed by Student's t test and Fisher's exact test.

RESULTS

Pancreata from obese mice were heavier (p<0.05) and had more fat histologically (p<0.05). Pancreata from obese mice had more triglycerides, FFAs, cholesterol, and total fat (p<0.05). Triglycerides represented 11% of pancreatic fat in lean mice compared with 67% of pancreatic fat in obese mice (p<0.01). Cytokines IL-1beta and TNF-alpha also were elevated in the pancreata of obese mice (p<0.05).

CONCLUSIONS

These data suggest that obese mice have 1) heavier pancreata, 2) more pancreatic fat, especially triglycerides and FFAs, and 3) increased cytokines. We conclude that obesity leads to nonalcoholic fatty pancreatic disease.

Endotoxin induces toll-like receptor 4 expression in vascular smooth muscle cells via NADPH oxidase activation and mitogen-activated protein kinase signaling pathways

OBJECTIVE

Toll-like receptor 4 (TLR4) plays a major role mediating endotoxin-induced cellular inflammation and regulates vascular smooth muscle cell (VSMC) proliferation, which is related to atherogenesis and restenosis. This study was conducted to investigate the mechanisms involved in lipopolysaccharide (LPS)-induced TLR4 expression in VSMCs.

METHODS AND RESULTS

Stimulation of human aortic smooth muscle cells (HASMCs) with LPS significantly increased TLR4 expression. The increase was regulated by nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (including the activation of subunits p47(phox) and Rac1), which mediates the production of reactive oxygen species and the activation of intracellular mitogen-activated protein kinase signaling pathways. Treatment with polyethylene-glycol-conjugated superoxide dismutase, N-acetylcysteine (NAC), diphenylene iodonium (DPI), or apocynin significantly decreased LPS-induced TLR4 expression. An actinomycin D chase experiment showed that LPS increased the half-life of TLR4 mRNA. Inhibition of NADPH oxidase activity by DPI, apocynin, or NAC significantly decreased TLR4 mRNA stability, as did the knock-down of RAC1 gene expression by RNA interference. We also demonstrated in an animal model that LPS administration led to a significant elevation of balloon-injury-induced neointimal hyperplasia, and of TLR4 expression, in rabbit aorta.

CONCLUSIONS

These findings suggest that NADPH oxidase activation, mRNA stabilization, and MAPK signaling pathways play critical roles in LPS-enhanced TLR4 expression in HASMCs, which contributes to vascular inflammation and cardiovascular disorders.

Interaction of oxidized low-density lipoprotein and the renin-angiotensin system in coronary artery disease

Hyperlipidemia and hypertension are frequently observed in patients with coronary artery disease. It has been proposed that an interaction between low-density lipoprotein, especially its oxidized form (ox-LDL), and renin-angiotensin system (RAS) activation is a major determinant of atherogenesis. Ox-LDL accumulation in the blood vessels enhances the expression and activation of RAS components; on the other hand, activation of RAS stimulates the accumulation of LDL and its oxidation into ox-LDL in the blood vessels. Individually ox-LDL and RAS activation induce oxidative stress and inflammatory cascade, whereas their combination exerts a synergistic effect. This concept of cross-talk between ox-LDL/hyperlipidemia and RAS activation has been proven in laboratory animals. Clinical trials also suggest that blockade of hyperlipidemia and RAS may have a synergistic salutary effect on the outcome of patients with hypertension and/or manifestations of atherosclerosis. This concept needs to be evaluated further in large clinical studies.

Homocysteine-induced vascular dysregulation is mediated by the NMDA receptor

Elevated plasma homocysteine accelerates myointimal hyperplasia and luminal narrowing after carotid endarterectomy. N-methyl D aspartate receptors (NMDAr) in rat cerebrovascular cells are involved in homocysteine uptake and receptor-mediated stimulation. In the vasculature, NMDAr subunits (NR1, 2A-2D) have been identified by sequence homology in rat aortic endothelial cells. Exposure of these cells to homocysteine increased expression of receptor subunits, an effect that was attenuated by dizocilpine (MK801), a noncompetitive NMDA inhibitor. The objective of this study was to investigate the existence of an NMDAr in rat vascular smooth muscle (A7r5) cells, and also the effect of homocysteine on vascular dysregulation as mediated by this receptor. Subunits of the NMDAr (NR1, 2A-2D) were detected in the A7r5 cells by using the reverse transcriptase polymerase chain reaction and Western blotting. Homocysteine induced an increase in A7r5 cell proliferation, which was blocked by MK801. Homocysteine, in a dose and time dependent manner, increased expression of matrix metallinoproteinase-9 and interleukin-1beta, which have been implicated in vascular smooth muscle cell migration and/or proliferation. Homocysteine reduced the vascular elaboration of nitric oxide and increased the elaboration of the nitric oxide synthase inhibitor, asymmetric dimethylarginine. All of these homocysteine mediated effects were inhibited by MK801. NMDAr exist in vascular smooth muscle cells and appear to mediate, at least in part, homocysteine-induced dysregulation of vascular smooth muscle cell functions.

Relationship of a comprehensive panel of plasma oxidized low-density lipoprotein markers to angiographic restenosis in patients undergoing percutaneous coronary intervention for stable angina

BACKGROUND

This study was performed to assess the relationship between oxidized low-density lipoprotein (OxLDL) and restenosis. OxLDL induces up-regulation of inflammatory genes and cytokines and recruits monocytes to the vessel wall. Elevated levels of monocytes post-percutaneous coronary intervention (PCI) are associated with in-stent restenosis.

METHODS AND RESULTS

One hundred forty-one patients with stable angina pectoris had serial blood samples drawn before PCI (68% balloon only, 32% stent), immediately post-PCI and at 6 and 24 hours, 3 days, 1 week, and 1, 3, and 6 months. Plasma levels of OxLDL-E06, a measure of oxidized phospholipid (OxPL) content on apoB-100 detected by antibody E06 (OxPL/apoB), autoantibodies to malondialdehyde-LDL and copper-oxidized LDL, and apoB-immune complexes were measured in all samples. Quantitative and qualitative coronary angiography was performed with 94% angiographic follow-up. Restenosis was defined as >50% diameter stenosis (%DS). The overall angiographic restenosis rate was 32% (39% in balloon group, 16% in stent group). OxPL/apoB levels rose significantly and OxLDL autoantibody titers decreased immediately post-PCI in patients both with and without restenosis, but there were no significant differences among groups. There was also no relationship of any OxLDL marker to lesion length, %DS, or minimal lumen diameter. No differences were noted in stent versus balloon-treated patients.

CONCLUSIONS

Serial measurement of a comprehensive panel of circulating OxLDL markers after uncomplicated PCI for stable angina does not predict restenosis.

Impact of IL-1β on flow-induced outward arterial remodeling

BACKGROUND

Flow reduction upregulates arterial wall interleukin 1beta (IL-1beta), and IL-1beta independently modulates intimal hyperplasia under low flow conditions. We hypothesized that IL-1beta expression is also augmented under high flow, and outward remodeling occurs by way of IL-1beta-dependent mechanisms.

METHODS

Carotid artery (CA) flow was surgically augmented in rabbits (n = 20). CAs were harvested at 1, 3, 7, and 14 days, and assayed via quantitative reverse transcriptase-polymerase chain reaction. IL-1 receptor I null mice (KO) and wild-type controls underwent unilateral CA ligation and harvest 4 weeks later to assess the impact of increased flow on the contralateral CA (n = 82).

RESULTS

The rabbit model led to an immediate 36% increase in contralateral flow (P = .01) with an 80% increase at 14 days (P = .016) with subsequent positive remodeling. High flow induced IL-1beta messenger RNA expression (114-fold at 1 day, P < .05), with levels remaining elevated through 14 days (61-fold, P < .05). In murine experiments, CA ligation resulted in a 44% increase in contralateral flow. Wild-type and KO animals responded with equivalent 83% and 78% increases in luminal area (P = .87).

CONCLUSIONS

Positive and negative perturbations of arterial blood flow induce IL-1beta in a time-dependent fashion. However, as opposed to intimal hyperplasia after flow reduction, positive arterial remodeling in response to increased flow occurs via IL-1beta independent mechanisms.

Proinflammatory cytokines regulate LOX-1 expression in vascular smooth muscle cells

OBJECTIVE

Atherogenesis represents a type of chronic inflammation and involves elements of the immune response, eg, the expression of proinflammatory cytokines. In advanced atherosclerotic lesions, lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) is expressed in endothelial cells, macrophages, and smooth muscle cells (SMCs). In vitro, the expression of LOX-1 is induced by inflammatory cytokines like TNF-alpha and transforming growth factor (TGF)-beta. Therefore, LOX-1 is thought to be upregulated locally in response to cytokines in vivo.

METHODS AND RESULTS

We determined by reverse-transcription polymerase chain reaction (PCR) and Western blot analysis whether the mediators of the acute phase response in inflammation, IL-1alpha, IL-1beta, and TNF-alpha, regulate LOX-1 expression in cultured SMC, and whether this regulation is influenced by peroxisome proliferator-activated receptor gamma (PPARgamma). We studied by immunohistochemistry whether these cytokines are spatially correlated with LOX-1 expression in advanced atherosclerotic lesions. We found upregulation of LOX-1 expression in SMC in a dose- and time-dependent manner after incubation with IL-1alpha, IL-1beta, and TNF-alpha. Simultaneous incubation with these cytokines at saturated concentrations had an additive effect on LOX-1 expression. The PPARgamma activator, 15d-PGJ(2), however, inhibited IL-1beta-induced upregulation of LOX-1. In the intima of atherosclerotic lesions regions of IL-1alpha, IL-1beta, and TNF-alpha expression corresponded to regions of LOX-1 expression.

CONCLUSIONS

We suppose that upregulated LOX-1 expression in SMC of advanced atherosclerotic lesions is a response to these proinflammatory cytokines. Moreover, the proinflammatory effects of these cytokines can be decreased by the antiinflammatory effect of PPARgamma.

Involvement of neuron-derived orphan receptor-1 (NOR-1) in LDL-induced mitogenic stimulus in vascular smooth muscle cells: role of CREB

OBJECTIVE

Low density lipoproteins (LDLs) modulate the expression of key genes involved in atherogenesis. Recently, we have shown that the transcription factor neuron-derived orphan receptor-1 (NOR-1) is involved in vascular smooth muscle cell (VSMC) proliferation. Our aim was to analyze whether NOR-1 is involved in LDL-induced mitogenic effects in VSMC.

METHODS AND RESULTS

LDL induced NOR-1 expression in a time- and dose-dependent manner. Antisense oligonucleotides against NOR-1 inhibit DNA synthesis induced by LDL in VSMCs as efficiently as antisense against the protooncogene c-fos. The upregulation of NOR-1 mRNA levels by LDL involves pertusis-sensitive G protein-coupled receptors, Ca2+ mobilization, protein kinases A (PKA) and C (PKC) activation, and mitogen-activated protein kinase pathways (MAPK) (p44/p42 and p38). LDL promotes cAMP response element binding protein (CREB) activation (phosphorylation in Ser133). In transfection assays a dominant-negative of CREB inhibits NOR-1 promoter activity, while mutation of specific (cAMP response element) CRE sites in the NOR-1 promoter abolishes LDL-induced NOR-1 promoter activity.

CONCLUSIONS

In VSMCs, LDL-induced mitogenesis involves NOR-1 upregulation through a CREB-dependent mechanism. CREB could play a role in the modulation by LDL of key genes (containing CRE sites) involved in atherogenesis.