Angioplasty-induced superoxide anions and neointimal hyperplasia in the rabbit carotid artery: suppression by the isoflavone trans-tetrahydrodaidzein

P212A Mutant of Dihydrodaidzein Reductase Enhances (S)-Equol Production and Enantioselectivity in a Recombinant Escherichia coli Whole-Cell Reaction System

(S)-Equol, a gut bacterial isoflavone derivative, has drawn great attention because of its potent use for relieving female postmenopausal symptoms and preventing prostate cancer. Previous studies have reported on the dietary isoflavone metabolism of several human gut bacteria and the involved enzymes for conversion of daidzein to (S)-equol. However, the anaerobic growth conditions required by the gut bacteria and the low productivity and yield of (S)-equol limit its efficient production using only natural gut bacteria. In this study, the low (S)-equol biosynthesis of gut microorganisms was overcome by cloning the four enzymes involved in the biosynthesis from Slackia isoflavoniconvertens into Escherichia coli BL21(DE3). The reaction conditions were optimized for (S)-equol production from the recombinant strain, and this recombinant system enabled the efficient conversion of 200 μM and 1 mM daidzein to (S)-equol under aerobic conditions, achieving yields of 95% and 85%, respectively. Since the biosynthesis of trans-tetrahydrodaidzein was found to be a rate-determining step for (S)-equol production, dihydrodaidzein reductase (DHDR) was subjected to rational site-directed mutagenesis. The introduction of the DHDR P212A mutation increased the (S)-equol productivity from 59.0 mg/liter/h to 69.8 mg/liter/h in the whole-cell reaction. The P212A mutation caused an increase in the (S)-dihydrodaidzein enantioselectivity by decreasing the overall activity of DHDR, resulting in undetectable activity for (R)-dihydrodaidzein, such that a combination of the DHDR P212A mutant with dihydrodaidzein racemase enabled the production of (3S,4R)-tetrahydrodaidzein with an enantioselectivity of >99%.

Nitric oxide inhibits neointimal hyperplasia following vascular injury via differential, cell-specific modulation of SOD-1 in the arterial wall

Superoxide (O2(•-)) promotes neointimal hyperplasia following arterial injury. Conversely, nitric oxide ((•)NO) inhibits neointimal hyperplasia through various cell-specific mechanisms, including redox regulation. What remains unclear is whether (•)NO exerts cell-specific regulation of the vascular redox environment following arterial injury to inhibit neointimal hyperplasia. Therefore, the aim of the present study was to assess whether (•)NO exerts cell-specific, differential modulation of O2(•-) levels throughout the arterial wall, establish the mechanism of such modulation, and determine if it regulates (•)NO-dependent inhibition of neointimal hyperplasia. In vivo, (•)NO increased superoxide dismutase-1 (SOD-1) levels following carotid artery balloon injury in a rat model. In vitro, (•)NO increased SOD-1 levels in vascular smooth muscle cells (VSMC), but had no effect on SOD-1 in endothelial cells or adventitial fibroblasts. This SOD-1 increase was associated with an increase in sod1 gene expression, increase in SOD-1 activity, and decrease in O2(•-) levels. Lastly, to determine the role of SOD-1 in (•)NO-mediated inhibition of neointimal hyperplasia, we performed the femoral artery wire injury model in wild type and SOD-1 knockout (KO) mice, with and without (•)NO. Interestingly, (•)NO inhibited neointimal hyperplasia only in wild type mice, with no effect in SOD-1 KO mice. In conclusion, these data show the cell-specific modulation of O2(•-) by (•)NO through regulation of SOD-1 in the vasculature, highlighting its importance on the inhibition of neointimal hyperplasia. These results also shed light into the mechanism of (•)NO-dependent redox balance, and suggest a novel VSMC redox target to prevent neointimal hyperplasia.

Serum myeloperoxidase/paraoxonase 1 ratio as potential indicator of dysfunctional high-density lipoprotein and risk stratification in coronary artery disease

OBJECTIVE

Granular leukocyte-derived myeloperoxidase (MPO) promotes oxidation of lipoproteins, while paraoxonase 1 (PON1) has antioxidant properties for high-density lipoprotein (HDL). We evaluated their effects on coronary risk stratification and function of lipoproteins.

METHODS AND RESULTS

A total 158 patients who had previously undergone percutaneous coronary intervention and who had been hospitalized for coronary re-angiography were enrolled. Coronary lesions (restenosis or de novo lesion) were observed in 84 patients but not associated with conventional lipid profile. In contrast, serum MPO levels and PON1 activities were significantly associated with the prevalence of coronary lesions. The high MPO/PON1 ratio, when cutoff values were set at 1.59, was independently correlated with restenosis (odds ratio 6.4, 95% CI 2.2-19.3, P = 0.001) and de novo lesions (odds ratio 3.5, 95% CI 1.3-9.4, P = 0.014). We isolated HDL from patients with high or low MPO/PON1 ratio, and compared anti-inflammatory properties of HDL. Human umbilical vein endothelial cells were stimulated with inflammatory cytokine, and the expression of vascular cell adhesion molecule-1 (VCAM-1) was evaluated. HDL isolated from patients with low serum MPO/PON1 ratio inhibited VCAM-1 expression significantly greater than that with high MPO/PON1 ratio. We also demonstrated that the cholesterol efflux capacity of apolipoprotein B-depleted serum from patients with high MPO/PON1 ratio was significantly decreased than that with low MPO/PON1 ratio.

CONCLUSIONS

MPO/PON1 ratio could be a useful marker for secondary prevention of coronary artery disease through modulation of HDL function.

Effects of Wenxiao Decoction on the expression of interleukin-6, intercellular adhesion molecular-1 and monocyte chemoattractant protein-1 in experimental atherosclerotic rabbits

OBJECTIVE

To observe the effects of different doses of Wenxiao Decoction on the expression of interleukin-6 (IL-6), intercellular adhesion molecule-1 (ICAM-1), and monocyte chemoattractant protein-1 (MCP-1) in experimental atherosclerotic rabbits and to explore the mechanism by which it alleviates atherosclerosis.

METHODS

Sixty New Zealand rabbits were randomly divided into six groups: a blank group, a model group, a Simvastatin group, and high-, medium-, and low-dosage Wenxiao Decoction groups. Except for those in the blank group, all rabbits were fed with a high-cholesterol diet. Carotid atherosclerosis was established by balloon-induced carotid artery endothelium injury in conjunction with the high-cholesterol diet. After 8 weeks, all animals were euthanized to evaluate levels of IL-6 and ICAM-1 expressions (by enzyme linked immunosorbent assay) and of MCP-1 (by immunohistochemistry staining).

RESULTS

The expressions of IL-6, ICAM-1, and MCP-1 were significantly increased in all groups except the blank group (P<0.05). However, the rabbits in the Wenxiao Decoction groups and the Simvastatin group showed significantly lower levels of IL-6, ICAM-1, and MCP-1 expression than those in the model group (P<0.05). The expressions of IL-6, ICAM-1, and MCP-1 in the highdosage Wenxiao Decoction group and the Simvastatin group were lower than those in the low-dosage Wenxiao Decoction group (P<0.05). The expression of MCP-1 in medium-dosage Wenxiao Decoction group was lower than that in the low-dosage group (P<0.05).

CONCLUSIONS

High, medium, and low doses of Wenxiao Decoction can inhibit the expressions of IL-6, ICAM-1, and MCP-1, which may prevent and stabilize atherosclerotic plaques. There may be a direct relationship between dosage and therapeutic efficacy of Wenxiao Decoction.

Effect of isoflavone on balloon catheter-induced neointimal hyperplasia in ovariectomised rabbit carotid artery

BACKGROUND

This study was designed to investigate the effects of phytoestrogen isoflavone on balloon catheter-induced hyperplasia of carotid artery.

METHODS

Forty-eight female New Zealand rabbits were randomly divided into four groups: control (balloon-induced carotid artery injury only); ovariectomy control (ovariectomy and carotid artery injury), oestrogen (ovariectomy, carotid artery injury and nilestriol, 5mg/kg daily for 28 days), and isoflavone (ovariectomy, carotid artery injury and isoflavone 120 mg/kg daily for 28 days). The arterial wall thickness was assessed by coloured ultrasonography, and the oestrogen-α and oestrogen-β receptors in the abdominal aorta were measured by Western blotting.

RESULTS

The medial layer thickness in the isoflavone group was less than in the ovariectomy control group (0.28±0.03 vs. 0.35±0.04 mm, p<0.01), and the intimal/medial layer (I/M) ratio is the isoflavone group was also less than in the ovariectomy control group (16.85±3.79 vs. 48.94±8.92, p<0.01). There was no statistically significant difference in the medial layer thickness or I/M ratio between the isoflavone and the oestrogen groups. The optical density of the oestrogen-α receptors in the isoflavone group (0.317±0.002) was less than in the oestrogen (0.633±0.002) or ovariectomy control group (0.590±0.001, p<0.01). The optical density of the oestrogen-β receptors in the isoflavone group (1.350±0.002) and the ovariectomy control group (1.2033±0.002) was less than in the oestrogen group (1.7699±0.003, p<0.01).

CONCLUSIONS

Isoflavone therapy in the ovariectomised rabbit model attenuated balloon catheter-induced intimal and medial layer hyperplasia in the carotid arteries. Down-regulation of the oestrogen-α receptors may be involved in the hyperplasia-preventative effect.

Effects of Wenxiao II decoction on the expression of MCP-1 and VCAM-1 in atherosclerotic rabbits

OBJECTIVE

To observe the effects of different doses of wenxiao II decoction on the expression of monocyte chemoattractant protein-1 (MCP-1) and vascular cell adhesion molecule-1 (VCAM-1) in an experimental model of atherosclerosis in rabbits and to explore the mechanism by which it alleviates atherosclerosis.

METHODS

Sixty 3-4 month-old New Zealand rabbits of both sexes were randomly divided into six groups: simvastain; model; blank; and high-dose, mid-dose, and low-dose wenxiao II decoction groups. Except for those in the blank group, all rabbits were fed a high-cholesterol diet. Carotid atherosclerosis was established by balloon-induced injury to the endothelium of the carotid artery in conjunction with consumption of a high-cholesterol diet. After 8 weeks, all rabbits were killed to evaluate the expression of MCP-1 and VCAM-1 by immunohistochemical staining.

RESULTS

Expressions of MCP-1 and VCAM-1 were significantly decreased in all groups except the blank group compared with the model group (P < 0.05). When compared with the simvastain group only variation of MCP-1 expression in low-dose group was not appreciable, and the differences were indistinct (P < 0.05). When comparing among wenxiao II decoction groups, MCP-1 expression in the mid- and high-dose groups was significantly lower than that seen in the low-dose group (P< 0.01), but there were no differences among three dosage groups with respect to VCAM-1 expression (P > 0.05).

CONCLUSION

These data suggested that high, mid, and low doses of Wenxiao II Decoction can inhibit the expression of MCP-1 and VCAM-1, which may prevent the formation of or stabilize atherosclerotic plaques. There may be a direct relationship between the dosage of wenxiao II decoction and its therapeutic efficacy.

From Skeleton to Cytoskeleton

Rationale:

The expression of osteocalcin is augmented in human atherosclerotic lesions. How osteocalcin triggers vascular pathogenesis and remodeling is unclear.

Objective:

To investigate whether osteocalcin promotes transformation of adventitial fibroblast to myofibroblasts and the molecular mechanism involved.

Methods and Results:

Immunohistochemistry indicated that osteocalcin was expressed in the neointima of renal arteries from diabetic patients. Western blotting and wound-healing assay showed that osteocalcin induced fibroblast transformation and migration, which were attenuated by blockers of the renin-angiotensin system and protein kinase Cδ (PKCδ), toll-like receptor 4 (TLR4) neutralizing antibody, and antagonist and inhibitors of free radical production and cyclooxygenase-2. Small interfering RNA silencing of TLR4 and PKCδ abolished fibroblast transformation. Angiotensin II level in the conditioned medium from the osteocalcin-treated fibroblasts was found elevated using enzyme immunoassay. Culturing of fibroblasts in conditioned medium collected from differentiated osteoblasts promoted fibroblast transformation. The expression of fibronectin, TLR4, and cyclooxygenase-2 is augmented in human mesenteric arteries after 5-day in vitro exposure to osteocalcin.

Conclusions:

Osteocalcin transforms adventitial fibroblasts to myofibroblasts through stimulating angiotensin II release and subsequent activation of PKCδ/TLR4/reactive oxygen species/cyclooxygenase-2 signaling cascade. This study reveals that the skeletal hormone osteocalcin cross-talks with vascular system and contributes to vascular remodeling.

Manganese superoxide dismutase inhibits neointima formation through attenuation of migration and proliferation of vascular smooth muscle cells

Superoxide anion is elevated during neointima development and is essential for neointimal vascular smooth muscle cell (VSMC) proliferation. However, little is known about the role of manganese superoxide dismutase (MnSOD, SOD2) in the neointima formation following vascular injury. SOD2 in the mitochondria plays an important role in cellular defense against oxidative damage. Because of its subcellular localization, SOD2 is considered the first line of defense against oxidative stress and plays a central role in metabolizing superoxide. Because mitochondria are the most important sources of superoxide anion, we speculated that SOD2 may have therapeutic benefits in preventing vascular remodeling. In this study, we used a rat carotid artery balloon-injury model and an adenoviral gene delivery approach to test the hypothesis that SOD2 suppresses vascular lesion formation. SOD2 was activated along with the progression of neointima formation in balloon-injured rat carotid arteries. Depletion of SOD2 by RNA interference markedly promoted the lesion formation, whereas SOD2 overexpression suppressed the injury-induced neointima formation via attenuation of migration and proliferation of VSMCs. SOD2 exerts its inhibitory effect on VSMC migration induced by angiotensin II by scavenging superoxide anion and suppressing the phosphorylation of Akt. Our data indicate that SOD2 is a negative modulator of vascular lesion formation after injury. Therefore, SOD2 augmentation may be a promising therapeutic strategy for the prevention of lesion formation in proliferative vascular diseases such as restenosis.

Antioxidants modulate the antiproliferative effects of nitric oxide on vascular smooth muscle cells and adventitial fibroblasts by regulating oxidative stress

BACKGROUND

S-nitrosothiols (SNO) release nitric oxide (NO) through interaction with ascorbic acid (AA). However, little is known about their combined effect in the vasculature. The aim of this study was to investigate the effect of AA on SNO-mediated NO release, proliferation, cell cycle progression, cell death, and oxidative stress in vascular cells.

METHODS

Vascular smooth muscle cells and adventitial fibroblasts harvested from the aortae of Sprague-Dawley rats were treated with AA, ± S-nitrosoglutathione (GSNO), or ± diethylenetriamine NONOate (DETA/NO). NO release, proliferation, cell cycle progression, cell death, and oxidative stress were determined by the Griess reaction, [(3)H]-thymidine incorporation, flow cytometry, trypan blue exclusion, and 5-(and-6)chloromethyl-2',7'dichlorodihydrofluorescein staining, respectively.

RESULTS

AA increased NO release from GSNO 3-fold (P < .001). GSNO and DETA/NO significantly decreased proliferation, but AA abrogated this effect (P < .05). Mirroring the proliferation data, changes in cell cycle progression induced by GSNO and DETA/NO were reversed by the addition of AA. GSNO- and DETA/NO-mediated increases in oxidative stress were significantly decreased by the addition of AA (P < .001).

CONCLUSIONS

Despite causing increased NO release from GSNO, AA reduced the antiproliferative and cell cycle effects of GSNO and DETA/NO through the modulation of oxidative stress.

Local arterial nanoparticle delivery of siRNA for NOX2 knockdown to prevent restenosis in an atherosclerotic rat model

Both atherosclerosis and arterial interventions induce oxidative stress mediated in part by nicotinamide adenine dinucleotide phosphate (NADPH) oxidases that have a pivotal role in the development of neointimal hyperplasia and restenosis. For small interfering RNA (siRNA) targeting of the NOX2 (Cybb) component of the NADPH oxidase to prevent restenosis, gene transfer with viral vectors is effective, but raises safety issues in humans. We developed a new approach using the amino-acid-based nanoparticle HB-OLD7 for local delivery of siRNA targeting NOX2 to the arterial wall. siRNA-nanoparticle complexes were transferred into the regional carotid artery walls after angioplasty in an atherosclerotic rat model. Compared with angioplasty controls, Cybb gene expression (measured by quantitative reverse transcriptase-PCR) in the experimental arterial wall 2 weeks after siRNA was reduced by >87%. The neointima-to-media-area ratio was decreased by >83%, and the lumen-to-whole-artery area ratio was increased by >89%. Vital organs showed no abnormalities and splenic Cybb gene expression showed no detectable change. Thus, local arterial wall gene transfer with HB-OLD7 nanoparticles provides an effective, nonviral system for efficient and safe local gene transfer in a clinically applicable approach to knock down an NADPH oxidase gene. Local arterial knockdown of the Cybb gene significantly inhibited neointimal hyperplasia and preserved the vessel lumen without systemic toxicity.

NOX and inflammation in the vascular adventitia

Vascular inflammation has traditionally been thought to be initiated at the luminal surface and progress through the media toward the adventitial layer. In recent years, however, evidence has emerged suggesting that the vascular adventitia is activated early in a variety of cardiovascular diseases and that it plays an important role in the initiation and progression of vascular inflammation. Adventitial fibroblasts have been shown to produce substantial amounts of NAD(P)H oxidase-derived reactive oxygen species (ROS) in response to vascular injury. Additionally, inflammatory cytokines, lipids, and various hormones, implicated in fibroblast proliferation and migration, lead to recruitment of inflammatory cells to the adventitial layer and impairment of endothelium-dependent relaxation. Early in the development of vascular disease, there is clear evidence for progression toward a denser vasa vasorum which delivers oxygen and nutrients to an increasingly hypoxic and nutrient-deficient media. This expanded vascularization appears to provide enhanced delivery of inflammatory cells to the adventitia and outer media. Combined adventitial fibroblast and inflammatory cell-derived ROS therefore are expected to synergize their local effect on adventitial parenchymal cells, leading to further cytokine release and a feed-forward propagation of adventitial ROS production. In fact, data from our laboratory and others suggest a broader paracrine positive feedback role for adventitia-derived ROS in medial smooth muscle cell hypertrophy and neointimal hyperplasia. A likely candidate responsible for the adventitia-derived paracrine signaling across the vessel wall is the superoxide anion metabolite hydrogen peroxide, which is highly stable, cell permeant, and capable of activating downstream signaling mechanisms in smooth muscle cells, leading to phenotypic modulation of smooth muscle cells. This review addresses the role of adventitial NAD(P)H oxidase-derived ROS from a nontraditional, perivascular vantage of promoting vascular inflammation and will discuss how ROS derived from adventitial NAD(P)H oxidases may be a catalyst for vascular remodeling and dysfunction.

DNA damage and repair in a model of rat vascular injury

Restenosis rate following vascular interventions still limits their long-term success. Oxidative stress plays a relevant role in this pathophysiological phenomenon, but less attention has been devoted to its effects on DNA damage and to the subsequent mechanisms of repair. We analysed in a model of arteriotomy-induced stenosis in rat carotids the time-dependent expression of DNA damage markers and of DNA repair genes, together with the assessment of proliferation and apoptosis indexes. The expression of the oxidative DNA damage marker 7,8-dihydro-8-oxo-2'-deoxyguanosine was increased at 3 and 7 days after arteriotomy, with immunostaining distributed in the injured vascular wall and in perivascular tissue. The expression of the DNA damage marker phospho-H2A.X was less relevant but increasing from 4 hrs to 7 days after arteriotomy, with immunostaining prevalently present in the adventitia and, to a lesser extent, in medial smooth muscle cells at the injury site. RT-PCR indicated a decrease of 8 out of 12 genes of the DNA repair machinery we selected from 4 hrs to 7 days after arteriotomy with the exception of increased Muyth and Slk genes (p<0.05). Western Blot revealed a decrease of p53 and catalase at 3 days after arteriotomy (p<0.05). A maximal 7% of BrdU-positive cells in endothelium and media occurred at 7 days after arteriotomy, while the apoptotic index peaked at 3 days after injury (p<0.05). Our results highlight a persistent DNA damage presumably related to a temporary decreased expression of the DNA repair machinery and of the antioxidant enzyme catalase, playing a role in stenosis progression.

Upregulation of peroxisome proliferator-activated receptor-gamma and NADPH oxidases are involved in restenosis after balloon injury

Restenosis is a major complication of percutaneous transluminal coronary angioplasty (PTCA) and is characterized by increased superoxide formation and accumulation of smooth muscle cells (SMCs). The mechanisms through which peroxisome proliferator-activated receptor-gamma (PPAR-gamma) modulates the pathological process are incompletely defined. In this study, balloon injury of porcine coronary arteries in vivo and cell scraping model in vitro were used to elucidate the pathway via this molecule. PPAR-gamma and NADPH oxidase expression significantly increased both in neointimal hyperplasia after balloon injury or in the cultured SMCs after scraping injury. In vitro, PPAR-gamma agonist 15-deoxy-Delta(12,14)-prostagladlin J(2) (15d-PGJ2) decreased cell-scraping-induced superoxide generation through suppression of NADPH oxidase activity via down-regulation of p22(phox) and gp91(phox). Furthermore, 15d-PGJ2 could suppress scraping-stimulated proliferation of SMCs. These data demonstrate that upregulation of PPAR-gamma and NADPH oxidases are involved in restenosis and activation of PPAR-gamma can inhibit the NADPH oxidase-dependent superoxide generation in SMCs after injury. These findings will provide a new potential drug target for restenosis after balloon injury.

Soybean-based biomaterials: preparation, properties and tissue regeneration potential

Future successes in regenerative medicine will depend on the development of new biodegradable biomaterials able to control tissue regeneration in vitro and in vivo. None of the products currently available to surgeons can combine all the essential characteristics for biodegradable biomaterials, which are tunable degradation rate, controlled inflammatory reaction, no toxicity and stimulation of tissue regeneration. These clinical features should be provided, together with ease of handling during surgery and cost-effective production. Here, an overview is presented of a novel class of soybean-based biomaterials, which can be manufactured as different hydrogel formulations, all tailored for specific clinical applications. ln vitro and in vivo studies have ascertained their activity on various biochemical and cellular components of regenerating tissues. Beyond their use, the ascertained bioactivity of some of the soybean components may open new investigations and commercial routes in regenerative medicine.

An isoflavone metabolite reduces arterial stiffness and blood pressure in overweight men and postmenopausal women

OBJECTIVES

Isoflavones reduce arterial stiffness, a predictor of cardiovascular events. Whether metabolites of isoflavones have similar bioactivity is unknown. The effect of supplemental trans-tetrahydrodaidzein (THD) a metabolite of daidzein on pulse wave velocity (PWV), a measure of arterial stiffness was tested in overweight men and postmenopausal women.

METHODS

25 subjects, 11 postmenopausal women, 14 men (age, 57 [7] years; body mass index, 30.3 [4.7]kg/m(2); mean [S.D.]) participated in a double-blind, randomized, cross-over trial of THD versus placebo.

DESIGN

2 weeks run-in followed by either THD 1g daily or placebo, each intervention 5 weeks. Aorta-femoral artery PWV, blood pressure and plasma lipids were measured after run-in, THD and placebo.

RESULTS

PWV was significantly reduced (signifying diminished central arterial stiffness): medians (25th and 75th%), placebo 9.9 m/s (8.7, 11.1), THD 8.8m/s (7.9, 10.9); RM ANOVA P=0.023, with Tukey procedure P<0.05. Systolic blood pressure was significantly reduced: means (S.D.), placebo 125.6 (14.7), THD 121.3 (12.2)mmHg; Tukey P<0.05. Plasma cholesterol, triglyceride and LDL cholesterol did not differ significantly. Absorption of THD >80% substantially exceeded that of parent isoflavones.

CONCLUSION

A metabolite normally formed after consumption of isoflavones (formononetin, daidezein), taken orally, reduced blood pressure and central arterial stiffness indicating reduced cardiovascular risk.