Periodontal infection is associated with endothelial dysfunction in healthy subjects and hypertensive patients

The purpose of this study was to evaluate endothelial function in patients with periodontitis. We evaluated forearm blood flow responses to acetylcholine and sodium nitroprusside in patients with periodontitis who had no other cardiovascular risk factors (32 men; 25+/-3 years of age), in a normal control group (20 men; 26+/-3 years of age), and in hypertensive patients with periodontitis (28 men and 10 women; 56+/-12 years of age) and without periodontitis (control group; 18 men and 6 women; 54+/-13 years of age). Forearm blood flow was measured using strain-gauge plethysmography. Circulating levels of C-reactive protein and interleukin-6 were significantly higher in the periodontitis group than in the control group. Both in healthy and hypertensive subjects, forearm blood flow responses to acetylcholine were significantly smaller in the periodontitis group than in the control group. Sodium nitroprusside-stimulated vasodilation was similar in the 2 groups. Periodontal therapy reduced serum concentrations of C-reactive protein and interleukin-6 and augmented acetylcholine-induced vasodilation in periodontitis patients with and without hypertension. After administration of N(G)-monomethyl-L-arginine, an NO synthase inhibitor, forearm blood flow response to acetylcholine was similar before and after treatment. These findings suggest that periodontitis is associated with endothelial dysfunction in subjects without cardiovascular risk factors, as well as hypertensive patients, through a decrease in NO bioavailability and that systemic inflammation may be, at least in part, a cause of endothelial dysfunction, leading to cardiovascular diseases.

Acute moderate-intensity exercise induces vasodilation through an increase in nitric oxide bioavailiability in humans

BACKGROUND

Long-term moderate-intensity exercise augments endothelium-dependent vasodilation through an increase in nitric oxide (NO) production. The purpose of this study was to determine the effects of different intensities of acute exercise on hemodynamics in humans.

METHODS

We evaluated forearm blood flow (FBF) responses to different intensities of exercise (mild, 25% maximum oxygen consumption [VO2max]; moderate, 50% VO2max; and high, 75% VO2max; bicycle ergometer, for 30 min) in eight healthy young men. The FBF was measured by using a strain-gauge plethysmography.

RESULTS

After exercise began, moderate-intensity exercise, but not mild-intensity exercise, promptly increased FBF from 2.8+/-1.1 mL/min/100 mL to a plateau at 5.4+/-1.6 mL/min/100 mL at 5 min (P<.01) and increased mean arterial pressure from 84.7+/-11.8 mm Hg to a plateau at 125.7+/-14.3 mm Hg at 5 min (P<.01). Moderate-intensity exercise decreased forearm vascular resistance (FVR) from 29.2+/-5.4 to 16.8+/-3.2 mm Hg/mL/min/100 mL tissue (P<.01). The administration of NG-monomethyl-L-arginine, an NO synthase inhibitor, abolished moderate exercise-induced augmentation of vasodilation. Although we were not able to measure FBF during high-intensity exercise because of large body motion, high-intensity exercise markedly increased mean arterial pressure from 82.6+/-12.2 to 146.8+/-19.8 mm Hg. High-intensity exercise, but not mild-intensity or moderate-intensity exercise, increased plasma concentration of 8-isoprostane, an index of oxidative stress, from 24.1+/-10.8 to 40.2+/-16.7 pg/mL (P<.05) at 10 min after the end of exercise.

CONCLUSIONS

These findings suggest that acute moderate-intensity exercise induces vasodilation through an increase in NO bioavailability in humans and that high-intensity exercise increases oxidative stress.

Interaction of obesity and skeletal bone mineral density in tooth retention in Japanese postmenopausal women

OBJECTIVE

To investigate whether being overweight is associated with increased or decreased risk of tooth loss in Japanese postmenopausal women.

DESIGN

The number of remaining teeth (total, anterior, and posterior teeth), mandibular bone height, and mandibular cortical mass were evaluated on the dental panoramic radiographs of 450 Japanese postmenopausal women. The bone mineral densities (BMDs) at the lumbar spine and femoral neck were measured by dual-energy x-ray absorptiometry. These measurements were compared among participants in three body mass index (BMI) categories (underweight, normal BMI, and overweight).

RESULTS

Analysis of covariance adjusted for confounding variables revealed that participants who were overweight had a significantly lower number of total (P = 0.019) and anterior (P = 0.012) remaining teeth than did those with normal BMI, although the former had significantly higher skeletal BMD values than the latter. No significant difference was observed in mandibular bone height between the overweight participants and those with normal BMI. There were no significant differences in the number of remaining teeth between the under- and overweight participants. Overweight participants had significantly higher skeletal BMDs (P < 0.001) and tended to have larger mandibular cortical masses than those who were underweight.

CONCLUSIONS

Despite their higher skeletal BMD, postmenopausal women who are overweight may have an increased risk of tooth loss, especially of the anterior teeth, compared with women who have normal BMI. This risk appears to be similar to that for underweight women.

Role of osteoprotegerin in arterial calcification: development of new animal model

OBJECTIVES

Enhanced osteoclastogenesis, increased bone resorption, and osteoporosis have been reported in osteoprotegerin-deficient (OPG (-/-)) mice. OPG (-/-) mice available in Japan usually do not show vascular calcification. We have found that arterial calcification can be quickly induced by a simple procedure in OPG (-/-) mice.

METHODS AND RESULTS

Male OPG (-/-), OPG (+/-), and OPG (+/+) mice were fed a high phosphate diet from 6 to 10 weeks after birth, and then 1alpha,25-dihydroxyvitamin D3 (calcitriol) was injected for 3 days. We found that severe calcification developed in the media of the aorta in OPG (-/-) mice. Under electron microscopy, calcium deposits were observed in the cytoplasm and extracellular matrix of vascular smooth muscle cells (VSMCs). Neither apoptosis of VSMCs nor infiltration of macrophages was observed. Alkaline phosphatase (ALP) activity of aortic tissue correlated with the calcified lesion area. Mouse aorta and bone extracts revealed an identical pattern by ALP electrophoresis.

CONCLUSIONS

Our results demonstrated that OPG had anticalcification activity in the aorta, probably through the downregulation of ALP activity. Because the time course of arterial calcification after the injection of calcitriol is accurate and reproducible, this mouse model will be useful for further investigation of vascular calcification.

Repetition of ischemic preconditioning augments endothelium-dependent vasodilation in humans: role of endothelium-derived nitric oxide and endothelial progenitor cells

BACKGROUND

Several studies have shown that both early and late effects of ischemic preconditioning (IPC) protect against myocardial injury after ischemic reperfusion.

METHODS AND RESULTS

The purpose of this study was to evaluate the late effects of IPC on endothelial function in humans. Late phase of IPC was induced by upper limb ischemia (cuff inflation of over 200 mm Hg for 5 minutes) 6 times a day for 1 month. We evaluated forearm blood flow (FBF) responses to acetylcholine (ACh) and to sodium nitroprusside (SNP) before and after IPC stimulus in 30 young healthy men. FBF was measured using a strain-gauge plethysmograph. The IPC stimulus significantly increased plasma concentration of vascular endothelial growth factor (VEGF), circulating level of endothelial progenitor cells (EPCs), and FBF responses to ACh, but these did not change in the control group. The FBF responses to SNP were similar before and after the IPC stimulus. Infusion of N(G)-monomethyl-L-arginine, a nitric oxide synthase inhibitor, completely eliminated the IPC stimulus-induced augmentation of FBF responses to ACh. In the contralateral arms of subjects that received the IPC stimulus, FBF responses to ACh did not change, but levels of VEGF and circulating EPCs increased.

CONCLUSIONS

These findings suggest that repetition of late IPC stimulus augments endothelium-dependent vasodilation in humans through increases in nitric oxide production and number of EPCs under a local condition. Repetition of IPC stimulus may be a simple, safe, and feasible therapeutic technique for endothelial protection of peripheral vessels.

Sarpogrelate Hydrochloride, a Selective 5-HT2A Antagonist, Improves Vascular Function in Patients With Peripheral Arterial Disease

Peripheral arterial disease (PAD) is 1 of the major manifestations of atherosclerosis. PAD is associated with endothelial dysfunction. Sarpogrelate hydrochloride, a selective 5-HT2A antagonist, has been widely used as an anti-platelet agent for the treatment of PAD. There is no information on whether endothelial function is improved after initiation of sarpogrelate treatment in patients with PAD. The purpose of this study was to evaluate the effects of sarpogrelate on endothelial function in patients with PAD. We divided PAD patients into 2 groups: those treated with sarpogrelate at a dose of 100 mg 3 times per day orally for 12 weeks (sarpogrelate group, n = 10), and those who remained on conventional therapy (control group, n = 11). Forearm blood flow (FBF) and leg blood flow (LBF) responses to reactive hyperemia (RH) and sublingual administration of nitroglycerin (NTG) were measured using strain-gauge plethysmography. After 12 weeks of sarpogrelate administration, FBF and LBF responses during RH showed significant increases from 13.2 +/- 1.7 to 18.1 +/- 2.2 mL/min per 100 mL tissue (P < 0.01) and from 8.2 +/- 0.9 to 14.2 +/- 2.1 mL/min per 100 mL tissue (P < 0.05), respectively. Sarpogrelate-induced augmentation of FBF and LBF responses to RH was maintained at 24 weeks. No change was observed in the control group at each follow-up time point. The changes in FBF and LBF after sublingual NTG were similar during follow-up periods in the 2 groups. These findings suggest that long-term oral administration of sarpogrelate improves vascular function in patients with PAD.

Roles of rho-associated kinase and oxidative stress in the pathogenesis of aortic stiffness

OBJECTIVES

The purpose of this study was to determine the relationship between Rho-associated kinase (ROCK) activity and aortic stiffness in humans.

BACKGROUND

Epidemiologic studies have shown that there is a relationship between aortic stiffness and cardiovascular complications. Recent evidence suggests that ROCK plays an important role in the process of atherosclerosis.

METHODS

We evaluated the forearm blood flow (FBF) response to sodium nitroprusside (SNP), a nitric oxide donor, acetylcholine (ACh), an endothelium-dependent vasodilator, and fasudil, a specific ROCK inhibitor, in 51 healthy male subjects (mean age 45.6 +/- 3.0 years). The FBF was measured by using a strain-gauge plethysmography. Carotid-femoral pulse wave velocity (cf-PWV) was measured to assess the aortic stiffness using a pulse wave velocimeter.

RESULTS

Intra-arterial infusion of SNP alone, ACh alone, or fasudil alone and after co-infusion of N(G)-monomethyl-L-arginine (L-NMMA), a nitric-oxide synthase inhibitor, significantly increased FBF in a dose-dependent manner (p < 0.01). Multivariate analysis showed that age and number of pack-years smoked were independent predictors of ROCK activity before or after co-infusion of L-NMMA (p < 0.01) and that age and ROCK activity before or after co-infusion of L-NMMA were independent predictors of cf-PWV (p < 0.01). The concentration of serum malondialdehyde-modified low-density lipoprotein, an index of oxidative stress, was significantly correlated with ROCK activity before and after co-infusion of L-NMMA and cf-PWV (p < 0.01).

CONCLUSIONS

These findings suggest that aging and accumulating smoking habit, which might induce excessive oxidative stress, are involved in ROCK activity in the vasculature, leading to an increase in aortic stiffness in humans.

Measurement of Flow-Mediated Vasodilation of the Brachial Artery A Comparison of Measurements in the Seated and Supine Positions

BACKGROUND

Measurement of flow-mediated vasodilation (FMD) is used to assess endothelial function in humans and according to the guidelines, subjects must remain supine during the study. However, measurement of FMD while seated would be more comfortable and convenient for patients, so the purpose of this study was to determine the effect of the patient's position on FMD results.

METHODS AND RESULTS

High-resolution ultrasonography, a linear array transducer (13 MHz) and an arm-holding device were used to measure arterial diameter in response to reactive hyperemia (FMD, cuff inflated to 50 mmHg above systolic blood pressure for 5 min) and in response to sublingual nitroglycerine (NTG, 75 microg) in 31 subjects, which included those with cardiovascular diseases. There was no significant difference between basal or peak hyperemic blood flow in the seated or supine position. Basal brachial artery diameter, FMD and vascular response to NTG were similar in both positions (basal diameter: 3.8+/-0.4 vs 3.9+/-0.4 mm, FMD: 7.3+/-4.3% vs 7.2+/-4.5%, NTG: 13.1+/-5.1% vs 12.8+/-5.6%).

CONCLUSIONS

The findings suggest that measurement of FMD in the seated position is as useful as measuring it in the supine position for assessing endothelial function. This flexibility of position is better for patients and physicians, and should lead to more widespread measurement of FMD.

Effects of acute administration of caffeine on vascular function

Caffeine is the most widely used pharmacologic substance in the world. It is found in common nonessential grocery items (e.g., coffee, tea, cocoa, and chocolate). The effects of caffeine on cardiovascular diseases, including hypertension, remain controversial, and there is little information on its direct effect on vascular function. The purpose of this study was to determine the effect of caffeine on endothelial function in humans. This study was a double-blind, randomized placebo and active drug study. Forearm blood flow (FBF) responses to acetylcholine (ACh), an endothelium-dependent vasodilator, and to sodium nitroprusside, an endothelium-independent vasodilator, were evaluated in healthy young men before and after the oral administration of caffeine 300 mg (n = 10) or placebo (n = 10). FBF was measured by using a strain-gauge plethysmograph. Caffeine significantly increased systolic and diastolic blood pressures by 6.0 +/- 6.0 and 2.6 +/- 3.1 mm Hg (p <0.05), respectively, but did not alter heart rate or baseline FBF. Caffeine augmented the FBF responses to ACh from 21.2 +/- 7.1 to 26.6 +/- 8.1 ml/min/100 ml tissue (p <0.05), whereas sodium nitroprusside-stimulated vasodilation was not altered by caffeine administration. The intra-arterial infusion of N(G)-monomethyl-L-arginine, a nitric oxide synthase inhibitor, abolished the caffeine-induced augmentation of FBF response to ACh. In the placebo group, the ACh- and sodium nitroprusside-stimulated vasodilation was similar before and after the follow-up period. In conclusion, these findings suggest that the acute administration of caffeine augments endothelium-dependent vasodilation in healthy young men through an increase in nitric oxide production.

Autologous bone marrow mononuclear cell implantation induces angiogenesis and bone regeneration in a patient with compartment syndrome

A 28-year-old man developed compartment syndrome in the right lower leg after fracture of the tibia and fibula. Despite fasciotomy, many arteries collapsed and union of the tibial and fibula fractures did not occur. Autologous bone marrow mononuclear cell (BMMNC) implantation for therapeutic angiogenesis and subsequent bone regeneration was performed and 4 weeks later, angiography showed a marked increase in collateral vessels surrounding the tibial fracture, and union was completed 6 months later. BMMNC implantation therapy might provide therapeutic angiogenesis and osteogensis in patients with compartment syndrome.

AT2 receptor mediates the cardioprotective effects of AT1 receptor antagonist in post-myocardial infarction remodeling

There are two subtypes of angiotensin (Ang) II receptors, AT1R and AT2R. It is established that clinical use of specific AT1R blocker (ARB) improves the long-term prognosis of heart failure. However, scientific basis for such effects of ARB is incompletely understood. The present study was designed to determine whether ARB inhibits the left ventricular (LV) remodeling that occurs early after myocardial infarction (MI) and whether the benefit of ARB is mediated by blockade of AT1R itself or by stimulation of AT2R resulting from AT1R blockade. MI was induced in AT2R-knockout mice and wild-type mice. Administration of valsartan, an ARB, or vehicle was started soon after the surgery and continued for two weeks. Infarction caused significant increase in end diastolic and end systolic LV dimensions, LV/body weight ratio, and myocyte cross-sectional area (MCSA) in both strains to a similar extent. Lung/body weight ratio, an index of pulmonary congestion, was also significantly increased in both strains, but the magnitude of increase was significantly larger in knockout mice. Valsartan significantly reduced LV dimensions, LV/body weight ratio, MCSA, and lung/body weight ratio in wild-type mice. In knockout mice, however, valsartan failed to inhibit the increases in LV dimensions and LV/body weight ratio. After the treatment, lung/body weight ratio in the mutant strain was significantly larger than that in the wild-type mice. Valsartan attenuates acute phase post-infarction remodeling and ameliorates heart failure, and a large part of its cardioprotective effect was mediated by AT2R.

Genetic ablation of the transcription repressor Bach1 leads to myocardial protection against ischemia/reperfusion in mice

Bach1 is a transcriptional repressor of heme oxygenase-1 gene (Hmox-1) and beta-globin gene. Heme oxygenase (HO)-1 is an inducible cytoprotective enzyme that degrades pro-oxidant heme to carbon monoxide (CO) and biliverdin/bilirubin, which are thought to mediate anti-inflammatory and anti-oxidant actions of HO-1. In the present study, we investigated the role of Bach1 in tissue protection against myocardial ischemia/reperfusion (I/R) injury in vivo using mice lacking the Bach1 gene (Bach1(-/-)) and wild-type (Bach1(+/+)) mice. In Bach1(-/-) mice, myocardial expression of HO-1 protein was constitutively up-regulated by 3.4-fold compared to that in Bach1(+/+) mice. While myocardial I/R induced HO-1 protein in ischemic myocytes in both strains of mice, the extent of induction was significantly greater in Bach1(-/-) mice than in Bach1(+/+) mice. Myocardial infarction was markedly reduced in size by 48.4% in Bach1(-/-) mice. Pretreatment of Bach1(-/-) mice with zinc-protoporphyrin, an inhibitor of HO activity, abolished the infarction-reducing effect of Bach1 disruption, indicating that reduction in the infarct size was mediated, at least in part, by HO-1 activity. Thus, Bach1 plays a pivotal role in setting the levels of both constitutive and inducible expression of HO-1 in the myocardium. Bach1 inactivation during I/R appears to be a key mechanism controlling the activation level of cytoprotective program involving HO-1.

Oxidative stress, endothelial function and angiogenesis induced by cell therapy and gene therapy

Recently, clinical studies have shown that novel therapies, including cell implantation and transfer of gene encoding for angiogenic growth factors, are effective in patients with critical limb ischemia who have no other treatment option. This concept is called therapeutic angiogenesis. Cell therapy involves implantation of bone-marrow or peripheral mononuclear cells and endothelial progenitor cells (CD34(+) cells) in the gastrocnemius of the ischemic leg. Gene therapy involves delivery of vascular endothelial growth factor and fibroblast growth factor using a plasmid or adenoviral vector. Critical limb ischemia is associated with endothelial dysfunction as well as excess oxidative stress. A balance of oxidative stress and nitric oxide play an important role in the development of atherosclerosis in patients with peripheral arterial diseases. It has been reported that both cell therapy and gene therapy improve endothelial function in the resistant artery of an ischemic limb. Cell therapy or gene therapy in combination with pharmacological therapy as an antioxidant could be useful for restoration of endothelial function and prevention of development of atherosclerosis in patients with critical limb ischemia. In this review, we discuss the relationships between oxidative stress, endothelial function, and angiogenesis and the mechanism by which therapeutic angiogenesis improves endothelial function.

Tetrahydrobiopterin improves aging-related impairment of endothelium-dependent vasodilation through increase in nitric oxide production

Deficiency of tetrahydrobiopterin (BH4), an essential cofactor for nitric oxide (NO) synthase, decreases NO production and increases reactive oxygen species. The purpose of this study was to elucidate the effects of aging on endothelial function and to determine whether the degree of BH4 deficiency is related to aging and oxidative stress. We evaluated forearm blood flow (FBF) responses to acetylcholine (ACh), an endothelium-dependent vasodilator, and isosorbide dinitrate (ISDN), an endothelium-independent vasodilator, before and after co-infusion of BH4 (500 mg/min) in 37 healthy men (mean age, 41+/-18 yr; range, 19-81 yr). FBF was measured using strain-gauge plethysmograph. Urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG) and serum malondialdehyde-modified low-density lipoprotein (MDA-LDL) were measured as indices of oxidative stress. Both ACh and ISDN increased the FBF in a dose-dependent manner in all subjects. Co-infusion of BH4 resulted in a significant increase in ACh-induced vasodilation (from 22.3+/-6.7 to 30.1+/-7.5 mL/min/100 mL tissue, P<0.05). Aging was found to be significantly correlated with ACh-induced vasodilation (r=-0.47, P=0.006), urinary 8-OHdG (r=0.38, P=0.02), serum MDA-LDL (r=0.36, P=0.02), and the change in ACh-induced vasodilation after co-infusion of BH4 (r=0.45, P=0.007). The FBF response to ISDN did not correlate with any parameters. Infusion of N(G)-monomethyl-L-arginine, an NO synthase inhibitor, abolished the BH4-induced enhancement of forearm vasorelaxation evoked by ACh. The increase in FBF after ISDN was not altered by BH4. These findings suggest that a deficiency of BH4 may be involved in the pathogenesis of disturbances in endothelium-dependent vasodilation related to aging through decrease in NO production and increase in oxidative stress.

Beneficial effect of T-type calcium channel blockers on endothelial function in patients with essential hypertension

Endothelial function is impaired in essential hypertension. T-type but not L-type voltage-gated Ca2+ channels were detected in the vascular endothelium. The purpose of the present study was to clarify the role of T-type Ca2+ channels in endothelial function. We studied flow-mediated vasodilation (FMD) and sublingual nitroglycerin (NTG)-induced vasodilation in the brachial artery. Forty patients with essential hypertension were randomly assigned to treatment with efonidipine, a T- and L-type Ca2+ channel blocker, or with nifedipine, an L-type Ca2+ channel blocker. Twenty healthy normotensive individuals were included as a control group. In patients with essential hypertension, FMD was attenuated and NTG was similar that of compared to healthy controls. After 12 weeks, the decrease in mean blood pressure in the efonidipine and nifedipine groups were similar. The endothelial function index, a ratio of FMD/NTG, was significantly increased by efonidipine (73 +/- 24 to 94 +/- 20%) but unchanged by nifedipine. Urinary excretion 8-hydroxy-2'-deoxyguanosine (8-OHdG) and serum malondialdehyde-modified low-density lipoprotein (LDL) were decreased by efonidipine but unchanged by nifedipine. These results suggest that a T-type Ca2+ channel blocker, but not an L-type Ca2+ channel blocker, may improve vascular endothelial dysfunction in patients with essential hypertension via a reduction in oxidative stress.

Adrenomedullin causes coronary vasodilation in humans: effects of inhibition of nitric oxide synthesis

Experimental studies have shown that adrenomedullin (AM) causes vasodilation, in part, mediated by endothelium-derived nitric oxide (NO). However, it remains to be clarified how NO is involved in AM-induced coronary vasoreactivity in humans. We examined whether NO contributes to the vasodilatory effects of adrenomedullin on human coronary arteries. In 10 patients with angiographically normal coronary arteries, adrenomedullin (low dose: 1 ng/kg/min; high dose: 10 ng/kg/min) was infused into the left coronary ostium before and after an infusion of N-monomethyl-L-arginine (L-NMMA, 40 micromol/min for 5 min), an NO synthase inhibitor. Coronary diameter and coronary blood flow (CBF) were evaluated by quantitative angiography and Doppler flow velocity measurements. Changes in these parameters in response to adrenomedullin were expressed as percent changes from baseline values. Adrenomedullin at a high dose dilated coronary arteries (3.7+/-0.5%, P<0.001). Adrenomedullin increased the coronary blood flow at both doses (low: 55.7+/-13.9%, P<0.01; high: 48.8+/-9.8%, P<0.001). After the infusion of L-NMMA, adrenomedullin-induced coronary vasodilation and increase in coronary blood flow were attenuated. These findings suggest that adrenomedullin dilates human coronary arteries through an increase in NO production, at least in part.

Heme oxygenase-1 gene enhancer manifests silencing activity in a chromatin environment prior to oxidative stress

The expression of heme oxygenase-1 (HO-1) is regulated by E1 and E2 enhancers, both of which contain multiple Maf recognition elements (MAREs). In living cells, MAREs are bound by Bach1/MafK heterodimers, hence maintaining a quiescent state of the HO-1 gene (hmox-1). However, in transient transfection assays, they act as transcriptional enhancers. Therefore MAREs may manifest their function only in a chromatin environment. By using NIH3T3 cell pools stably transfected with EGFP reporter genes driven by the wild-type or mutated E2 enhancer, we demonstrate that the E2 MAREs function as transcriptional silencers depending on the binding of Bach1/MafK heterodimer in vivo only in a chromatin environment. After cadmium treatment, they switched into transcriptional enhancers. Surprisingly, single MARE site did not exhibit such function. Furthermore, by using DNase I hypersensitivity assay, we demonstrate that simple chromatin condensations were not involved in the Bach1-mediated repression. We conclude that, in a chromatin environment, the E2 MAREs function as transcriptional silencers depending on binding of Bach1/MafK heterodimer.

Induction of Heme Oxygenase-1 Inhibits Monocyte Chemoattractant Protein-1 mRNA Expression in U937 Cells

Heme oxygenase-1 (HO-1) is a stress-inducible isoform of HO with potential cytoprotective effects. Monocyte activation/migration mediated by monocyte chemoattractant protein-1 (MCP-1) is one of the earliest and important events in the pathogenesis of atherosclerosis. We examined the effect of HO-1 on the production of lysophosphatidylcholine (Lyso-PC)-induced MCP-1 in the human promonocytic cell line U937. Increased HO-1 induction by hemin resulted in a significant decrease in the Lyso-PC-mediated induction of MCP-1 mRNA expression. SnPP (IX), the specific inhibitor of HO-1 enzymatic activity, prevented the hemin-mediated attenuation of MCP-1 mRNA expression. These results suggest that HO-1 may work as an anti-atherogenic agent through the attenuation of MCP-1 production.

Smoking, Endothelial Function, and Rho-Kinase in Humans

Objective— Smoking is associated with endothelial dysfunction and activated Rho-kinase in vascular smooth muscle cells (VSMCs) in humans. The purpose of this study was to elucidate the relationship between endothelial function and Rho-kinase activity in forearm VSMCs in healthy young men.

Methods and Results— We evaluated the forearm blood flow (FBF) responses to acetylcholine (ACh), fasudil, a Rho-kinase inhibitor, and sodium nitroprusside (SNP) in male smokers (n=10) and nonsmokers (n=14). FBF was measured by using a strain-gauge plethysmography. The vasodilatory effect of ACh was significantly smaller in smokers than that in nonsmokers. The vasodilatory effect of fasudil was significantly greater in smokers than that in nonsmokers. The vasodilatory effects of SNP in the 2 groups were similar. There was a significant correlation between the maximal FBF response to fasudil and that to ACh ( r =−0.67; P <0.01). There was no significant correlation between the maximal FBF response to fasudil and that to SNP. The intra-arterial coinfusion of fasudil significantly increased the FBF response to ACh in smokers but not in nonsmokers. There were no significant differences between FBF response to fasudil alone and that in combination with N G -monomethyl- l -arginine in smokers and in nonsmokers. The intra-arterial coinfusion ascorbic acid did not alter the FBF response to fasudil in both groups.

Conclusions— These findings suggest that smoking is involved in not only endothelial dysfunction but also activation of Rho-kinase in VSMCs in forearm circulation, and that there is a significant correlation between endothelial function and Rho-kinase activity in VSMCs.

Role of the JNK pathway in thrombin-induced ICAM-1 expression in endothelial cells

OBJECTIVE

Thrombin induces leukocyte adherence to endothelial cells via increased expression of intercellular adhesion molecule-1 (ICAM-1). Although ICAM-1 expression is regulated by NF-kappaB, recent studies have suggested that additional signaling mechanisms may also be involved. The goal of this study was to determine whether mitogen-activated protein (MAP) kinases, including extracellular signal-regulated kinase 1/2 (ERK1/2), c-Jun N-terminal kinase (JNK), and p38 MAP kinase (p38), mediate thrombin-induced ICAM-1 expression in endothelial cells.

METHODS

Western blot analysis using anti-ICAM-1 antibody and luciferase assays were performed in cultured endothelial cells after addition of signal transduction inhibitors or transfection of various gene constructs. JNK kinase activity was determined by a kinase assay using c-Jun as a substrate or by Western blot analysis with anti-phospho-JNK antibody.

RESULTS

Treatment of endothelial cells with the JNK-specific inhibitors, SP600125 or JNK inhibitory peptide 1 (JNKI1), resulted in a significant decrease in thrombin-induced ICAM-1 expression as demonstrated by Western blot analysis (67 +/- 3% and 72 +/- 7%, respectively). In contrast, inhibitors of MEK and p38 had only minimal effect. The combination of SP600125 and the NF-kappaB inhibitor, BAY11-7082, resulted in complete inhibition of thrombin-induced ICAM-1 expression. The Galpha(q) inhibitor, YM-254890, inhibited thrombin-induced JNK activation and ICAM-1 expression. Dominant-negative Ras and Rac1, but not Rho, inhibited thrombin-induced JNK activation and ICAM-1 promoter activity. Finally, thrombin-induced JNK activation and ICAM-1 promoter activity were inhibited by betaARK1ct (a Gbetagamma subunit scavenger) and Csk.

CONCLUSIONS

These data suggest that, in concert with NF-kappaB, JNK regulates thrombin-induced ICAM-1 expression by a mechanism that is dependent on Galpha(q), Gbetagamma, Ras, Rac1 and the Src kinase family.