Feng Yen Lin

Salvianolic acid B attenuates VCAM-1 and ICAM-1 expression in TNF-α-treated human aortic endothelial cells

Attachment to, and migration of leukocytes into the vessel wall is an early event in atherogenesis. Expression of cell adhesion molecules by the arterial endothelium may play a major role in atherosclerosis. It has been suggested that antioxidants inhibit the expression of adhesion molecules and may thus attenuate the processes leading to atherosclerosis. In the present study, the effects of a potent water‐soluble antioxidant, salvianolic acid B (Sal B), and an aqueous ethanolic extract (SME), both derived from a Chinese herb, Salvia miltiorrhiza, on the expression of endothelial‐leukocyte adhesion molecules by tumor necrosis factor‐α (TNF‐α)‐treated human aortic endothelial cells (HAECs) were investigated. When pretreated with SME (50 and 100 μg/ml), the TNF‐α‐induced expression of vascular adhesion molecule‐1 (VCAM‐1) was notably attenuated (77.2 ± 3.2% and 80.0 ± 2.2%, respectively); and with Sal B (1, 2.5, 5, 10, and 20 μg/ml), 84.5 ± 1.9%, 78.8 ± 1.2%, 58.9 ± 0.4%, 58.7 ± 0.9%, and 57.4 ± 0.3%, respectively. Dose‐dependent lowering of expression of intercellular cell adhesion molecule‐1 (ICAM‐1) was also seen with SME or Sal B. In contrast, the expression of endothelial cell selectin (E‐selectin) was not affected. SME (50 μg/ml) or Sal B (5 μg/ml) significantly reduced the binding of the human monocytic cell line, U937, to TNF‐α‐stimulated HAECs (45.7 ± 2.5% and 55.8 ± 1.2%, respectively). SME or Sal B significantly inhibited TNF‐α‐induced activation of nuclear factor kappa B (NF‐κB) in HAECs (0.36‐ and 0.48‐fold, respectively). These results demonstrate that SME and Sal B have anti‐inflammatory properties and may explain their anti‐atherosclerotic properties. This new mechanism of action of Sal B and SME, in addition to their previously reported inhibition of LDL, may help explain their efficacy in the treatment of atherosclerosis. J. Cell. Biochem. 82:512–521, 2001.

Matrix Metalloproteinase-9 Is Essential for Ischemia-Induced Neovascularization by Modulating Bone Marrow–Derived Endothelial Progenitor Cells

Objective—Both matrix metalloproteinases (MMPs) and endothelial progenitor cells (EPCs) have been implicated in the process of neovascularization. Here we show that the impaired neovascularization in mice lacking MMP-9 is related to a defect in EPC functions in vasculogenesis. Methods and Results—Hindlimb ischemia surgery was conducted in MMP-9−/− mice and wild-type (MMP-9+/+) mice. Blood flow recovery was markedly impaired in MMP-9−/− mice when compared with that in wild-type mice as determined by laser Doppler imaging. Flow cytometry demonstrated that the number of EPC-like cells (Sca-1+/Flk-1+) in peripheral blood increased in wild-type mice after hindlimb ischemia surgery and exogenous vascular endothelial growth factor stimulation, but not in MMP-9−/− mice. Plasma levels and bone marrow concentrations of soluble Kit-ligand (sKitL) were significantly elevated in wild-type mice in response to tissue ischemia, but not in MMP-9−/− mice. C-kit positive bone marrow cells of MMP-9−/− mice have attenuated adhesion and migration than those isolated from wild-type mice. In in vitro studies, incubation with selective MMP-9 inhibitor suppressed the colony formation, migration, and tube formation capacities of EPC. Transplantation of bone marrow cells from wild-type mice restored collateral flow formation in MMP-9−/− mice. Conclusions—These findings suggest that MMP-9 deficiency impairs ischemia-induced neovascularization, and these effects may occur through a reduction in releasing the stem cell-active cytokine, and EPC mobilization, migration, and vasculogenesis functions.

Intake of Red Wine Increases the Number and Functional Capacity of Circulating Endothelial Progenitor Cells by Enhancing Nitric Oxide Bioavailability

Objective—Red wine (RW) consumption has been associated with a reduction of cardiovascular events, but limited data are available on potential mediating mechanisms. This study tested the hypothesis that intake of RW may promote the circulating endothelial progenitor cell (EPC) level and function through enhancement of nitric oxide bioavailability. Methods and Results—Eighty healthy, young subjects were randomized and assigned to consume water (100 mL), RW (100 mL), beer (250 mL), or vodka (30 mL) daily for 3 weeks. Flow cytometry was used to quantify circulating EPC numbers, and in vitro assays were used to evaluate EPC functions. After RW ingestion, endothelial function determined by flow-mediated vasodilation was significantly enhanced; however, it remained unchanged after water, beer, or vodka intake. There were significantly increased numbers of circulating EPC (defined as KDR+CD133+, CD34+CD133+, CD34+KDR+) and EPC colony-forming units only in the RW group (all P<0.05). Only RW ingestion significantly enhanced plasma levels of nitric oxide and decreased asymmetrical dimethylarginine (both P<0.01). Incubation of EPC with RW (but not beer or ethanol) and resveratrol in vitro attenuated tumor necrosis factor-α–induced EPC senescence and improved tumor necrosis factor-α–suppressed EPC functions and tube formation. Incubation with nitric oxide donor sodium nitroprusside significantly ameliorated the inhibition of tumor necrosis factor-α on EPC proliferation, but incubation with endothelial nitric oxide synthase inhibitor l-NAME and PI3K inhibitor markedly attenuated the effect of RW on EPC proliferation. Conclusion—The intake of RW significantly enhanced circulating EPC levels and improved EPC functions by modifying nitric oxide bioavailability. These findings may help explain the beneficial effects of RW on the cardiovascular system. This study demonstrated that a moderate intake of RW can enhance circulating levels of EPC in healthy subjects by increasing nitric oxide availability. Direct incubation of EPC with RW and resveratrol can modify the functions of EPC, including attenuation of senescence and promotion of EPC adhesion, migration, and tube formation. These data suggest that RW ingestion may alter the biology of EPC, and these alterations may contribute to its unique cardiovascular-protective effect.

Increased circulating CD31+/annexin V+ apoptotic microparticles and decreased circulating endothelial progenitor cell levels in hypertensive patients with microalbuminuria

Objective Microalbuminuria is associated with an increased risk for all-cause and cardiovascular mortality, but the pathophysiologic mechanism underlying the association between urinary albumin excretion and cardiovascular disease remains unclear. Here, we tested the hypothesis that enhanced endothelial apoptotic microparticles and decreased endothelial progenitor cell (EPC) levels might contribute to the pathophysiology of microalbuminuria or macroalbuminuria in cardiovascular disease. Methods Flow cytometry was used to assess endothelial cell apoptosis and circulating EPC levels by quantification of circulating CD31+/annexin V+ apoptotic microparticles and EPC markers (defined as KDR+CD133+, CD34+CD133+, CD34+KDR+) in peripheral blood. Results In total, 125 patients with hypertension were enrolled in the study, of whom 80 patients (64%) were with normoalbuminuria (albumin excretion rate of <20 μg/min, overnight urine samples), 35 patients (28%) with microalbuminuria (an albumin excretion rate of 20–200 μg/min), and 10 patients (8%) with macroalbuminuria (an albumin excretion rate >200 μg/min). Compared to hypertensive patients with normoalbuminuria, patients with microalbuminuria or macroalbuminuria had significantly more diabetes (P = 0.005), higher systolic blood pressure (P = 0.018), and elevated serum creatinine levels (P < 0.001). Among the three groups, patients with microalbuminuria or macroalbuminuria had significantly increased CD31+/annexin V+ apoptotic microparticles (1.8 ± 2.2 versus 3.0 ± 4.3 versus 5.2 ± 6.2%, P = 0.044) and decreased circulating EPC numbers (P < 0.05). By multivariate analysis, CD31+/annexin V+ apoptotic microparticle level was an independent predictor of urinary albumin excretion rate in hypertensive patients (P < 0.001). Microparticles isolated from hypertensive patients with microalbuminuria or macroalbuminuria attenuated EPC proliferation, migration, and increased H2O2 production, cellular senescence and apoptosis in comparison with those from hypertensive patients with normoalbuminuria. Conclusion These findings suggest that hypertensive patients with microalbuminuria or macroalbuminuria have increased endothelial apoptotic microparticles and decreased circulating EPC levels, which may contribute to atherosclerotic disease progression and enhanced cardiovascular risk in hypertensive patients with nephropathy.

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 p47phox 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. Conclusion—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.

Resveratrol inhibits human lung adenocarcinoma cell metastasis by suppressing heme oxygenase 1‐mediated nuclear factor‐κB pathway and subsequently downregulating expression of matrix metalloproteinases

Resveratrol exhibits potential anti-carcinogenic activities. Heme oxygenase-1 (HO-1) is involved in angiogenesis and tumor metastasis. Matrix metalloproteinases (MMPs) are key enzymes in the degradation of extracellular matrix, and their expression may be dysregulated in lung cancer metastasis. In this study, we investigated the anti-invasive mechanism of resveratrol in lung cancer cells. HO-1 was shown to be elevated (approximately 4.7-fold) in lung cancer tumor samples as compared with matched normal tissues. After treatment of lung adenocarcinoma cell line A549 cells with resveratrol (50 microM) for 24 h, the migratory and invasive abilities (38 and 30% inhibition, respectively) of A549 cells were significantly reduced. Resveratrol significantly inhibited HO-1-mediated MMP-9 (35% inhibition) and MMP-2 (28% inhibition) expression in lung cancer cells. Nuclear factor (NF)-kappaB inhibitor induced a marked reduction in MMP-9 and MMP-2 expression, suggesting NF-kappaB pathway could play an important role. Furthermore, HO-1 inhibition and silencing significantly suppressed MMPs and invasion of lung cancer cells. Our results suggest that resveratrol inhibited HO-1 and subsequently MMP-9 and MMP-2 expression in lung cancer cells. The inhibitory effects of resveratrol on MMP expression and invasion of lung cancer cells are, in part, associated with the HO-1-mediated NF-kappaB pathway.

Nrf-2 mediated heme oxygenase-1 expression, an antioxidant-independent mechanism, contributes to anti-atherogenesis and vascular protective effects of Ginkgo biloba extract.

AIMS Vascular protective effects of Ginkgo biloba extract (GBE) may involve both antioxidant-related and anti-inflammatory mechanisms. GBE was recently suggested as a heme oxygenase (HO)-1 inducer. The role of HO-1 in anti-atherogenesis and related vascular protective effects of GBE awaited further clarification. METHODS AND RESULTS Tumor necrosis factor (TNF)-α was used to stimulate adhesiveness of human aortic endothelial cells (HAECs) to monocytes, an in vitro sign simulating atherogenesis. Pretreatment with GBE reduced TNF-α-stimulated endothelial adhesiveness, which could be attenuated by HO-1 inhibitors ZnPP IX or SnPP IX. GBE increased HO-1 expression and enzyme activity in HAECs. Pretreatment with MAP kinase inhibitor SB203580 significantly reduced GBE-induced HO-1 expression. Furthermore, GBE activated the translocation of the transcription factor nuclear factor-erythroid 2-related factor 2 (Nrf2), and increased its binding to the antioxidant response element (ARE) of the HO-1 gene. Pretreatment with PEG-SOD or other antioxidant reagents did not alter GBE-induced endothelial HO-1 expression. In vivo study also showed that GBE treatment could reduce leukocyte adherence to injury arteries, and enhance HO-1 expression in circulating monocytes and in arteries after wire injury, suggesting the in vivo induction of HO-1 by GBE. CONCLUSION GBE could inhibit cytokine-induced endothelial adhesiveness by inducing HO-1 expression via the activation of p38 and Nrf-2 pathways, a mechanism in which oxidative stress is not directly involved. GBE might exert its anti-atherogenesis and vascular protective effects by inducing vascular HO-1 expression.

Antioxidative and hepatoprotective effects of magnolol on acetaminophen-induced liver damage in rats.

Acute liver failure (ALF), an often fatal condition characterized by massive hepatocyte necrosis, is frequently caused by drug poisoning, particularly with acetaminophen (N-acetyl-p-aminophenol/APAP). Hepatocyte necrosis is consecutive to glutathione (GSH) depletion and mitochondrial damage caused by reactive oxygen species (ROS) overproduction. Magnolol, one major phenolic constituent of Magnolia officinalis, have been known to exhibit potent antioxidative activity. In this study, the anti-hepatotoxic activity of magnolol on APAP-induced toxicity in the Sprague-Dawley rat liver was examined. After evaluating the changes of several biochemical parameters in serum, the levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), and lactate dehydrogenase (LDH) were elevated by APAP (500 mg/kg) intraperitoneal administration (8 and 24 h) and reduced by treatment with magnolol (0.5 h after APAP administration; 0.01, 0.1, and 1 μg/kg). Histological changes around the hepatic central vein, lipid peroxidation (thiobarbituric acid-reactive substance/TBARS), and GSH depletion in liver tissue induced by APAP were also recovered by magnolol treatment. The data show that oxidative stress followed by lipid peroxidation may play a very important role in the pathogenesis of APAP-induced hepatic injury; treatment with lipid-soluble antioxidant, magnolol, exerts anti-hepatotoxic activity. Our study points out the potential interest of magnolol in the treatment of toxic ALF.

Salvianolic acid B attenuates cyclooxygenase-2 expression in vitro in LPS-treated human aortic smooth muscle cells and in vivo in the apolipoprotein-E-deficient mouse aorta.

Inflammation plays an essential role in atherosclerosis and post‐angioplasty restenosis and the synthesis and release of inflammatory cytokines from vascular smooth muscle cells is an important contributor to these pathologies. It is assumed that drugs that prevent the overproduction of inflammatory cytokines may inhibit cardiovascular disorders. In the present study, the effects of a water‐soluble antioxidant, salvianolic acid B (Sal B), derived from a Chinese herb, on the expression of cyclooxygenase (COX) in lipopolysaccharide (LPS)‐treated human aortic smooth muscle cells (HASMCs) and in the aortas of cholesterol‐fed apoE deficient mice were investigated. In unstimulated HASMCs, COX‐2 mRNA and protein were almost undetectable, but were strongly upregulated in response to LPS. In contrast, HASMCs with or without LPS treatment showed constitutive expression of COX‐1 mRNA and protein. The activation of COX‐2 protein synthesis in LPS‐stimulated HASMCs was shown to involve the activation of the extracellular‐signal‐regulated kinase 1/2 (ERK1/2), c‐Jun NH2‐terminal kinase (JNK), and p38 mitogen‐activated protein kinase pathway. Incubation of HASMCs with Sal B before LPS stimulation resulted in pronounced downregulation of COX‐2 expression. Sal B treatment suppressed ERK1/2 and JNK phosphorylation and attenuated the increase in prostaglandin E2 production and NADPH oxidase activity in LPS‐treated HASMCs. When apoE‐deficient mice were fed a 0.15% cholesterol diet with or without supplementation with 0.3% Sal B for 12 weeks, the intima/media area ratio in the thoracic aortas was significantly reduced in the Sal B group (0.010 ± 0.009%) compared to the apoE‐deficient group (0.114 ± 0.043%) and there was a significant reduction in COX‐2 protein expression in the thickened intima. These results demonstrate that Sal B has anti‐inflammatory properties and may explain its anti‐atherosclerotic properties. This new mechanism of action of Sal B, in addition to its previously reported inhibition of LDL oxidation, may help explain its efficacy in the treatment of atherosclerosis. J. Cell. Biochem. 98: 618–631, 2006.

Endothelial progenitor cell dysfunction in cardiovascular diseases: Role of reactive oxygen species and inflammation

Endothelial progenitor cells (EPCs) move towards injured endothelium or inflamed tissues and incorporate into foci of neovascularisation, thereby improving blood flow and tissue repair. Patients with cardiovascular diseases have been shown to exhibit reduced EPC number and function. It has become increasingly apparent that these changes may be effected in response to enhanced oxidative stress, possibly as a result of systemic and localised inflammatory responses. The interplay between inflammation and oxidative stress affects the initiation, progression, and complications of cardiovascular diseases. Recent studies suggest that inflammation and oxidative stress modulate EPC bioactivity. Clinical medications with anti-inflammatory and antioxidant properties, such as statins, thiazolidinediones, angiotensin II receptor 1 blockers, and angiotensin-converting enzyme inhibitors, are currently administered to patients with cardiovascular diseases. These medications appear to exert beneficial effects on EPC biology. This review focuses on EPC biology and explores the links between oxidative stress, inflammation, and development of cardiovascular diseases.