Monocyte-endothelial cell interaction in atherogenesis and thrombosis

Cellular interactions between leukocytes and the endothelium are critical events in vascular biology, such as atherosclerosis and acute coronary syndrome. When monocytes and endothelial cells are activated via direct cell-cell interaction, both types of cells express several biologically active molecules such as adhesion molecules, cytokines, coagulation and fibrinolytic factors, metalloproteinases, and vasoactive substances. All of these molecules could contribute to atherogenesis and thrombosis.

Interleukin-6 and acute coronary syndrome

The designation of atherosclerosis as a chronic inflammatory process represents an exciting and logical paradigm shift for cardiologists. Plasma concentrations of interleukin-6 (IL-6) and its hepatic by-product C-reactive protein (CRP) appear to reflect the intensity of occult plaque inflammation and by inference may determine vulnerability to rupture. Indeed, circulating IL-6 levels are elevated in patients with acute myocardial infarction (AMI), and also in patients with unstable, but not with stable angina. Coronary sinus IL-6 concentrations are also increased after percutaneous coronary intervention (PCI), and late restenosis correlates with an increase in IL-6 concentration after the procedure, indicating that IL-6 expression may be not only related to instability of atheromatous plaques, but also to the formation of restenotic lesions after PCI. These observations suggest the advantage of screening for circulating IL-6 concentration and the use of anti-inflammatory treatment for those thought be at high risk to reduce the risk of future AMI.

Lack of association between the insertion/deletion polymorphism of the angiotensin-converting enzyme gene and vasospastic angina

BACKGROUND AND HYPOTHESIS

It has been suggested that the insertion/deletion (I/D) polymorphism of the angiotensin-converting enzyme (ACE) gene is an independent risk factor for coronary atherosclerosis and myocardial infarction, but its relation to vasospastic angina has not been fully proven. In the present study, we investigated the possible relationship between the ACE I/D genotype and vasospastic angina.

METHODS

We explored the distribution of the ACE genotype in 20 patients with vasospastic angina without fixed coronary artery stenosis, 55 angina patients with fixed coronary artery stenosis, and 30 control subjects without coronary artery disease.

RESULTS

The frequency of the DD genotype in patients with vasospastic angina (DD: 30.0%, ID: 20.0%, II: 50.0%) did not differ from that in the control subjects (DD: 23.3%, ID: 26.7%, II: 50.0%), while the frequency in patients with coronary artery stenosis (DD: 43.7%, ID: 21.8%, II: 34.5%) was significantly higher than that in the control subjects. The frequency of the D allele also did not differ between patients with vasospastic angina (0.40) and control subjects (0.37), while the frequency was significantly higher in patients with coronary artery stenosis (0.55).

CONCLUSIONS

These findings suggest that the ACE DD genotype is a potent genetic risk factor for organic coronary artery disease, while it confers no appreciable increase in risk of vasospastic angina. These results also suggest the diversity of the pathogenesis of vascular lesions in these two types of coronary artery disease.

Myotonic dystrophy associated with QT prolongation and torsade de pointes

A rare case of myotonic dystrophy (MD) with congestive heart failure, associated with QT prolongation and torsade de pointes (TdP) is reported. A 53-year-old woman was admitted to the hospital because of congestive heart failure. Electrocardiograph (ECG) showed first-degree atrioventricular block and QT prolongation. During hospitalization, TdP appeared but returned to sinus rhythm spontaneously. As the patient had quadriplegia, a myopathic face, cataracts, diabetes mellitus, and an increased number of cytosine-thymineguanine (CTG) repeats (760 repeats), she was diagnosed as having MD. Electrocardiographic analysis of her family also revealed abnormal QT(U) prolongation in her daughter and brother who both had MD, while ECG findings of other family members without MD were normal. Thus, the presence of QT(U) prolongation was associated with MD in this family.

Biochemical markers of coagulation activation in mitral stenosis, atrial fibrillation, and cardiomyopathy

Advances in the understanding of the biochemistry of the mechanism of hemostasis have led to the development of sensitive methods for determining levels of markers which reflect thrombin activity (thrombin-antithrombin III complex, fibrinopeptide A, F1 + 2 fragment), active fibrinolysis (D-dimer, plasmin-alpha 2-plasmin inhibitor complex), and platelet activity (platelet factor 4, beta-thromboglobulin) in vivo. Measurement of these markers may be useful in identifying patients with various cardiovascular disorders at high risk of thromboembolism.

Hypocalcemic heart failure: a reversible form of heart muscle disease

This paper reports the case of a 53-year-old woman with hypocalcemia-induced reversible cardiomyopathy. Laboratory tests showed hypocalcemia caused by idiopathic hypoparathyroidism. Her left ventricular dysfunction persisted for a long period even after normalization of the serum calcium level. Observations suggest that physicians should be aware that hypocalcemia can be a reversible cause of cardiomyopathy and congestive heart failure.

Right ventricular dysplasia with complete atrioventricular block: necessity and limitation of left ventricular epicardial pacing

This paper reports a case of right ventricular dysplasia, in which the patient presented with atrioventricular block and was followed for more than 8 years under left ventricular epicardial pacing. Five years after first epicardial pacemaker implantation, loss of capture occurred. Replacement of the epicardial leads was performed.

Local implantation of autologous mononuclear cells from bone marrow and peripheral blood for treatment of ischaemic digits in patients with connective tissue diseases

OBJECTIVE

CD34-positive bone marrow mononuclear cells (MNCs) have been successfully used for regeneration of small arteries in Buerger's disease. The objective of this study is to examine the angiogenetic potential of autologous MNCs from bone marrow and peripheral blood implanted into the ischaemic digits from patients with connective tissue diseases.

METHODS

Three patients with systemic sclerosis, two with mixed connective tissue disease, and one with CREST syndrome were enrolled who had painful ischaemic digits with necrosis refractory to several vasodilators including intravenous prostaglandins. MNCs obtained from 7 ml/kg bone marrow blood and 400 ml peripheral blood were implanted into 20 different sites in palms and/or soles. The study was performed open-labelled.

RESULTS

Pain in the numeric rating scale improved remarkably up to 1 month after implantation of bone marrow or peripheral MNCs to the same extent, although no significant differences were found in transcutaneous oxygen pressure and thermogram before and after the implantation. Bone marrow MNCs increased blood flow of the hand determined by intra-arterial digital subtraction angiography, while peripheral MNCs did not.

CONCLUSIONS

Implantation of autologous MNCs from peripheral and bone marrow into the ischaemic digits was so effective in pain-relief and more clinical trials would be warranted to see whether this could be a new treatment modality for angiogenesis in connective tissue diseases as in Buerger's disease.

Adeno-associated virus vector-mediated interleukin-10 gene transfer inhibits atherosclerosis in apolipoprotein E-deficient mice

Inflammation is a major contributor to atherosclerosis by its effects on arterial wall biology and lipoprotein metabolism. Interleukin-10 (IL-10) is an anti-inflammatory cytokine that may modulate the atherosclerotic disease process. We investigated the effects of adeno-associated virus (AAV) vector-mediated gene transfer of IL-10 on atherogenesis in apolipoprotein E (ApoE)-deficient mice. A murine myoblast cell line, C2C12, transduced with AAV encoding murine IL-10 (AAV2-mIL10) secreted substantial amounts of IL-10 into conditioned medium. The production of monocyte chemoattractant protein-1 (MCP-1) by the murine macrophage cell line, J774, was significantly inhibited by conditioned medium from AAV2-mIL10-transduced C2C12 cells. ApoE-deficient mice were injected with AAV5-mIL10 into their anterior tibial muscle at 8 weeks of age. The expression of MCP-1 in the vascular wall of the ascending aorta and serum MCP-1 concentration were decreased in AAV5-mIL10-transduced mice compared with AAV5-LacZ-transduced mice. Oil red-O staining of the ascending aorta revealed that IL-10 gene transfer resulted in a 31% reduction in plaque surface area. Serum cholesterol concentrations were also significantly reduced in AAV5-mIL10-transduced mice. To understand the cholesterol-lowering mechanism of IL-10, we measured the cellular cholesterol level in HepG2 cells, resulting in its significant decrease by the addition of IL-10 in a dose-dependent manner. Furthermore, IL-10 suppressed HMG-CoA reductase expression in the HepG2 cells. These observations suggest that intramuscular injection of AAV5-mIL10 into ApoE-deficient mice inhibits atherogenesis through anti-inflammatory and cholesterol-lowering effects.

Increased urinary 15-F2t-isoprostane concentrations in patients with non-ischaemic congestive heart failure: a marker of oxidative stress

OBJECTIVE

To investigate a novel marker of oxidative stress in patients with congestive heart failure (CHF).

PATIENTS

15 patients with mild CHF, 15 patients with severe CHF with acute exacerbation, and 15 control subjects.

MAIN OUTCOME MEASURES

Measurement of urinary 15-F2t-isoprostane, plasma brain natriuretic peptide (BNP), serum interleukin 6 (IL-6), and serum thrombomodulin concentrations. In patients with severe CHF, samples were taken at admission and 4, 7, and 14 days after admission.

RESULTS

Urinary 15-F2t-isoprostane, plasma BNP, and serum IL-6 concentrations in patients with severe CHF were significantly higher than those in control subjects or in patients with mild CHF. However, concentrations of serum thrombomodulin, a marker of endothelial damage, were not different between patients with CHF and control subjects. In addition, urinary 15-F2t-isoprostane, plasma BNP, and serum IL-6 concentrations in patients with severe CHF gradually decreased in proportion to the severity of CHF during hospitalisation. Interestingly, urinary 15-F2t-isoprostane concentrations significantly correlated with plasma BNP concentrations and serum IL-6 concentrations, but not with serum thrombomodulin concentrations.

CONCLUSIONS

Urinary 15-F2t-isoprostane concentrations increased in proportion to the severity of CHF in patients. This may be caused by increased 15-F2t-isoprostane production. These findings suggest that urinary 15-F2t-isoprostane may be a marker of morbidity as well as oxidative stress in patients with CHF.

Macrophage migration inhibitory factor as a redox-sensitive cytokine in cardiac myocytes

OBJECTIVE

Macrophage migration inhibitory factor (MIF), which plays a pivotal role in the control of inflammatory responses, was first characterized as a T-cell cytokine, but later was also found as a pituitary peptide released in response to infection and stress. However, MIF's role and expression in the myocardium has never been reported. The goal of this study is to examine MIF in the myocardium.

METHODS AND RESULTS

MIF protein and mRNA levels were assayed using enzyme-linked immunosorbent assay (ELISA) and reverse transcription-polymerase chain reaction (RT-PCR), respectively. Increased MIF concentrations were detected in the sera of patients with acute myocardial infarction (AMI). In cultured rat cardiac myocytes, significant amounts of MIF were produced in response to hypoxia and hydrogen peroxide (H(2)O(2)), but not to angiotensin II, endothelin-1, interleukin-1beta (IL-1beta) or tumor necrosis factor alpha (TNFalpha). H(2)O(2)-induced MIF production increased in a time- and dose-dependent manner and was completely abolished in the presence of catalase. H(2)O(2) also induced MIF mRNA expression. The H(2)O(2)-induced MIF production was completely inhibited by the protein kinase C (PKC) inhibitor GF109203X, partially inhibited by the tyrosine kinase inhibitor herbimycin A, and uninhibited by calcium chelation or phorbol ester-sensitive PKC down-regulation. This suggests that H(2)O(2)-induced MIF production is mediated by an atypical PKC isoform. DNA microarray analysis revealed that 52 genes were preferentially expressed in response to MIF. Of these, the MIF-induced expression of both glutathione S-transferase (GST) and lipopolysaccharide-induced CXC chemokine (LIX) mRNAs was confirmed using RT-PCR analysis.

CONCLUSION

The present results suggest that MIF is expressed by the myocardium in response to redox stress and may play a role in the pathogenesis of myocardial ischemia.

Serum hepatocyte growth factor levels are increased in patients with congestive heart failure

BACKGROUND

Hepatocyte growth factor (HGF) is a potent endothelial cell-specific mitogen. We investigated the clinical importance of HGF in congestive heart failure (CHF).

METHODS AND RESULTS

Thirty-five patients with acute exacerbation of CHF and 7 control subjects were examined. Serum and peripheral blood mononuclear cells (PBMCs) were isolated from peripheral blood on days 1, 7, and 14 after admission. PBMCs were cultured at a density of 1 x 10(7) cells/mL for 24 hours. HGF levels in serum and the PBMC culture medium and serum interleukin 6 (IL-6) levels were measured by enzyme-linked immunosorbent assay. Serum HGF levels in patients with CHF were markedly increased at admission compared with those in control subjects and gradually returned to control levels during hospitalization. HGF levels in the PBMC culture medium were also significantly increased in CHF patients compared with control subjects. There was a positive correlation between HGF levels in serum or those in the PBMC culture medium and serum IL-6 levels. HGF levels in serum and the culture medium were not notably different between CHF patients regularly treated with and without angiotensin-converting enzyme inhibitors.

CONCLUSIONS

HGF levels in serum are increased in patients with acute exacerbation of CHF.

Peroxisome proliferator-activated receptor gamma activators inhibit cardiac hypertrophy in cardiac myocytes

BACKGROUND

Peroxisome proliferator-activated receptors (PPARs) are transcription factors belonging to the nuclear receptor superfamily. PPARgamma mRNA is present in cardiac myocytes; however, whether PPARgamma affects cardiac hypertrophy remains unknown.

METHODS AND RESULTS

We investigated the effects of PPARgamma activators on cardiac hypertrophy in neonatal rat cardiac myocytes. Cyclic 4% biaxial mechanical strain caused enlargement of cardiac myocytes (1.3-fold versus control, P<0.0001), but the PPARgamma activators troglitazone and 15-deoxy-Delta(12-14)-prostaglandin J(2) (15d-PGJ(2)) (10 micromol/L) inhibited this effect (troglitazone, -72%, P<0.0005; 15d-PGJ(2), -88%, P<0.0002). Total cell protein was increased by mechanical strain (control, 164.3 microgram/dish; strain, 265.5, P<0.0002), and this effect was inhibited by troglitazone and 15d-PGJ(2) (troglitazone, -61%, P<0.005; 15d-PGJ(2), -72%, P<0.001). [(3)H]Leucine uptake was also increased by mechanical strain (1.9-fold versus control, P<0.002), and this increase was inhibited by troglitazone and 15d-PGJ(2) (troglitazone, -52% at 10 micromol/L, P<0.01; 15d-PGJ(2), -70% at 10 micromol/L, P<0.005). An increase in [(3)H]leucine uptake induced by angiotensin II or phenylephrine was significantly inhibited by troglitazone and 15d-PGJ(2). Mechanical strain induced mRNA expression for brain natriuretic peptide, but PPARgamma activators inhibited this induction. Furthermore, PPARgamma activators inhibited mechanically induced activation of nuclear factor (NF)-kappaB. Pyrrolidine dithiocarbamate, an inhibitor of NF-kappaB activation, inhibited strain-induced [(3)H]leucine uptake (-50% at 100 micromol/L, P<0.05).

CONCLUSIONS

These results demonstrate that PPARgamma activators inhibit cardiac hypertrophy in cardiac myocytes and suggest that PPARgamma activators may regulate cardiomyocyte hypertrophy at least partially through the NF-kappaB pathway.

Tissue factor expression in coronary circulation as a prognostic factor for late restenosis after coronary angioplasty

We investigated changes in blood coagulation in the coronary circulation after percutaneous transluminal coronary angioplasty (PTCA) and its clinical significance. We examined 43 patients with ischemic heart disease who underwent elective PTCA of isolated stenotic lesions in the left coronary artery. Ten patients underwent PTCA alone, 15 received percutaneous transluminal rotational atherectomy (PTRA) and 18 stent implantation. Blood samples were drawn from the coronary sinus before and immediately after PTCA, as well as 4 and 24 h later. Plasma levels of tissue factor (TF), thrombin-antithrombin III complex (TAT) and prothrombin fragment 1+2 (F 1+2) were measured by enzyme-linked immunosorbent assay. Follow-up coronary angiography was performed 6 months after PTCA. Minimal luminal diameter was assessed by quantitative coronary angiography to evaluate late loss index. TF, TAT and F 1+2 levels in the coronary sinus blood showed significant increases 24 h after PTCA. A significant positive correlation was found between changes in TF levels 24 h after PTCA and late loss index 6 months after the procedure. TF levels in the coronary sinus blood were significantly higher in patients with late restenosis than in those without restenosis. These results suggest that TF expression in the coronary circulation after PTCA is a prognostic factor for late restenosis.

Neurogenic pulmonary edema and large negative T waves associated with subarachnoid hemorrhage

We describe a 72-year-old woman with hypertension who developed acute neurogenic pulmonary edema and giant negative T waves on electrocardiography (ECG) due to subarachnoid hemorrhage. The patient was alert and complained of precordial chest discomfort, dyspnea and shoulder stiffness. Echocardiography demonstrated normal left ventricle contraction with hypertrophy. Computed tomography (CT) and subsequent cerebral angiography revealed subarachnoid hemorrhage and saccular aneurysm at the anterior communicating artery. It is important to consider the possibility of subarachnoid hemorrhage when a patient shows pulmonary edema and ECG abnormalities even without typical clinical signs of subarachnoid hemorrhage.

Lipophilic statins augment inducible nitric oxide synthase expression in cytokine-stimulated cardiac myocytes

Nitric oxide production by inducible nitric oxide synthase (iNOS) may play an important role in the pathogenesis of cardiovascular dysfunction. We investigated the effects of statins on iNOS expression and subsequent nitric oxide synthesis in cardiac myocytes and the mechanism by which statins exert their effects. We measured the production of nitrite, a stable metabolite of nitric oxide, in cultured neonatal rat cardiac myocytes with the Griess reagent. iNOS mRNA and protein expression were assayed by reverse transcription polymerase chain reaction and Western blotting, respectively. The lipophilic statins fluvastatin and lovastatin significantly increased interleukin-1beta-induced nitrite production by cardiac myocytes, whereas hydrophilic pravastatin did not. Increased nitrite production by fluvastatin was accompanied by increased iNOS mRNA and protein accumulation. Exogenous mevalonate, but not squalene, significantly blocked the stimulatory effect of fluvastatin on nitrite production. Cotreatment with geranylgeranyl-pyrophosphate also reversed the effect of fluvastatin. Furthermore, both Rho inhibitor C3 exoenzyme and Rho kinase inhibitor Y-27632 significantly increased interleukin-1beta-induced nitrite accumulation in cardiac myocytes. These results demonstrated that lipophilic statins upregulate iNOS expression and subsequent nitric oxide formation in cardiac myocytes via inhibition of Rho.

Pleiotropic effects of statins on the vascular tissue

The statins are lipid-lowering agents that act by inhibition of 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase. This enzyme is responsible for the conversion of HMG-CoA to mevalonate. Products of mevalonate metabolism are critical for several cellular processes of eukaryotic cells, and inhibition of the mevalonate pathway by statins has pleiotropic effects. It has been reported that statins inhibit the migration and proliferation of vascular smooth cells (VSMCs), reduce interleukin-6 expression in VSMCs, improve endothelium-dependent vasomotion, and inhibit the expression of plasminogen activator inhibitor-1 and matrix metalloproteinases in endothelial cells. These effects of statins are independent of plasma cholesterol level, and are completely blocked by exogenous mevalonate and some isoprenoids. These findings suggest that statins exert direct antiatherosclerotic effects on the vascular wall beyond their effects on plasma lipids.

Chemokine expression in coronary circulation after coronary angioplasty as a prognostic factor for restenosis

Recent studies have clarified the significance of chemokines in cardiovascular diseases, such as development of atherosclerosis, atheromatous plaque rupture and restenosis after coronary angioplasty. We investigated changes in chemokine expression in the coronary circulation induced by percutaneous transluminal coronary angioplasty (PTCA) and their clinical significance. We examined 40 patients with angina pectoris who underwent elective PTCA for isolated stenotic lesions of the left coronary artery. Eight patients received PTCA only, 14 percutaneous transluminal rotational atherectomy and 18 stent implantation. Venous blood samples were obtained from the coronary sinus before, and immediately after as well as 4 and 24 h after PTCA. Plasma levels of interleukin (IL)-8, macrophage-colony stimulating factor (M-CSF) and monocyte chemoattractant protein-1 (MCP)-1 were measured by enzyme-linked immunosorbent assay. Plasma levels of M-CSF in the coronary sinus blood showed significant increases 4 and 24 h after PTCA. On the other hand, plasma MCP-1 levels did not change significantly during a 24-h observation period after PTCA. Immunoreactive IL-8 was not detected in any patients before or after PTCA. A significant positive correlation was found between plasma M-CSF levels 24 h after PTCA and late loss index 6 months after the procedure. Plasma levels of M-CSF 24 h after PTCA were significantly higher in patients with than in those without late restenosis. PTCA induced increases in plasma levels of M-CSF in the coronary circulation. Increased M-CSF expression may be involved in neointima formation at injured vessels through activation of mononuclear phagocytes.

Isolated tricuspid valve endocarditis due to Candida parapsilosis associated with long-term central venous catheter implantation

A 72-year-old man was treated for fungal tricuspid valve endocarditis (TVE) with significant tricuspid valvular regurgitation and severe congestive heart failure caused by Candida parapsilosis. The patient had received hyperalimentation and antibiotic therapy for three months through a central venous catheter after the surgical treatment of ileus. The patient was treated medically with amphotericin B and fluconazole because of high surgical risk due to severe pulmonary emphysema, and he responded well. Although TVE caused by C. parapsilosis is rare, we should consider this possibility in patients receiving long-term hyperalimentation and antibiotic therapy using a central venous catheter.

Interaction between monocytes and vascular endothelial cells induces adrenomedullin production

Adrenomedullin (AM), a potent vasodilator peptide, has natriuretic effects, and its plasma concentration is elevated in cardiovascular diseases. In the present study, we investigated the induction of AM expression due to interactions between THP-1 cells (human monocytic cell line) and human umbilical cord vein endothelial cells (HUVECs). AM levels in the culture medium were measured by radioimmunoassay. The luciferase vector containing the 5'-flanking region of the human AM gene was transfected into either HUVECs or THP-1 cells. Addition of THP-1 cells to HUVECs for 48 h induced marked increases in AM levels, which were 16-fold higher than those of HUVECs alone. Luciferase vectors containing the 5'-flanking region of human AM gene (pLCF-1534) were transferred into THP-1 cells or HUVECs. Addition of THP-1 cells to pLCF-1534-transfected HUVECs induced an increase in luciferase activity in cell lysates, which was 5-fold higher than that of the transfected HUVECs alone. In contrast, the luciferase activity of lysates from pLCF-1534-transfected THP-1 cells was not affected by coculture with HUVECs. A separate coculture experiment revealed that direct contact of THP-1 cells and HUVECs contributed to enhanced AM production in the cocoulture. Co-incubation of the cell membrane fraction from THP-1 cells augmented AM production by HUVECs. Both anti-interleukin (IL)-1alpha antibody and IL-1 receptor antagonist significantly inhibited AM production in the cocultures. The cell-to-cell interaction between monocytes and HUVECs induces AM production by HUVECs, which may play an important role in the pathogenesis of vascular disorders.

Expression of matrix metalloproteinases in patients with acute myocardial infarction

This study investigated the clinical significance of matrix metalloproteinases (MMPs) in acute myocardial infarction (AMI) and the involvement of peripheral blood mononuclear cells (PBMCs), which are a possible source of MMPs in AMI. Forty patients with AMI were recruited. Plasma and PBMCs were isolated from peripheral blood on days 1, 7, 14 and 21 after the onset of AMI. Levels of MMP-1 and MMP-2 were measured by enzyme-linked immunosorbent assay. The MMP-1 level in the culture medium of PBMCs after incubation for 24h was designated as 'PBMC-MMP-1 level.' Plasma MMP-1 did not significantly change during the course of AMI, but the plasma MMP-2 levels increased gradually after the onset of AMI with maximum elevation on day 21 after onset. Plasma MMP-2 activity also became significantly elevated during the course of AMI. PBMC-MMP-1 levels in the patients were significantly higher than those in control subjects over the course of AMI. Significant positive correlations were observed between maximum PBMC-MMP-1 levels and maximum plasma C-reactive protein levels (r=+0.55, p<0.01) and left ventricular end-diastolic volume index (r=+0.63, p<0.001). In conclusion, plasma MMP-2 levels and activity and MMP-1 production by PBMCs are increased in patients with AMI. Inflammation after AMI may enhance production of MMP-1 by PBMCs. These changes may play an important role in the ventricular remodeling that occurs after AMI by promoting the degradation of the extracellular matrix.

Torsades de pointes ventricular tachycardia induced by mosapride and flecainide in the presence of hypokalemia

We report a 68-year-old man who developed torsades de pointes ventricular tachycardia induced by combined use of mosapride and flecainide. He had a permanent pacemaker (DDD mode) implanted because of sick sinus syndrome (bradytachy syndrome) 6 years earlier. The patient had started taking mosapride for upper abdominal discomfort 2 weeks earlier. On admission, ECG showed prolongation of the QTc interval from 0.48 to 0.56 seconds and self-terminating torsades de pointes occurred. We considered that this proarrhythmia was induced by mosapride in combination with antiarrhythmic agents.

Adeno-associated virus-mediated transfer of endothelial nitric oxide synthase gene inhibits protein synthesis of rat ventricular cardiomyocytes

We investigated whether nitric oxide (NO) synthase gene transfer could attenuate growth of cultured cardiac myocytes. First, we investigated the effects of exogenous NO and cGMP analog on protein synthesis of cultured neonatal rat cardiac myocytes. The NO donor 3-morpholino-sydnonimine-hydrochloride (SIN-1) and 8-bromo-cGMP caused concentration-dependent decreases in phenylephrine-stimulated incorporation of 3H-leucine into cardiac myocytes. We then transferred endothelial constitutive NO synthase (ecNOS) gene into cultured neonatal rat cardiac myocytes using adeno-associated virus (AAV) vectors. ecNOS gene transfer into cardiac myocytes induced 140 kD ecNOS protein expression and significantly increased cGMP contents of myocytes compared with control cells. ecNOS gene transfer inhibited 3H-leucine incorporation into cardiac myocytes in response to phenylephrine, which was significantly recovered in the presence of the NOS inhibitor N(G)-monomethyl-L-arginine acetate. These results indicate that endogenously generated NO by ecNOS gene transfer using AAV vectors inhibits the alpha-adrenergic agonist-induced cardiac protein synthesis at least partially via cGMP production.

Adeno-associated virus-mediated transfer of endothelial nitric oxide synthase gene reduces the vasoconstrictive response

BACKGROUND

Adeno-associated virus (AAV) has a number of attractive features for gene therapy including the ability to transduce nondividing cells and long term transgene expression.

OBJECTIVE

To investigate whether the endothelial constitutive nitric oxide synthase (ecNOS) gene can be efficiently introduced into rat aortic segments using AAV vectors and thereby modulate the vasoconstrictive response.

ANIMALS AND METHODS

Excised rat aortas were incubated with medium containing ecNOS-expressing AAV vectors (AAV-ecNOS). Expression of ecNOS in the aortic segments was evaluated by immunohistochemical staining. The isometric tension of the aortic segments transduced with AAV-ecNOS was measured.

RESULTS

Adventitial cells in rat aortic segments were efficiently transduced with AAV-ecNOS. The vasoconstrictive response induced by 30 mmol/L K(+) was enhanced in endothelium-denuded aortic segments compared with intact aortic segments. However, in endothelium-denuded aortic segments transduced with AAV-ecNOS, the enhancement of the vasoconstrictive response disappeared. This effect induced by ecNOS gene transfer was abolished in the presence of the nitric oxide synthase inhibitor N(G)-monomethyl-l-arginine acetate.

CONCLUSIONS

These results show that ecNOS gene transfer using AAV vectors abolishes the pathological enhancement of the vasoconstrictive response in endothelium-denuded aortic segments.

Fluvastatin upregulates inducible nitric oxide synthase expression in cytokine-stimulated vascular smooth muscle cells

Nitric oxide (NO) production by inducible NO synthase (iNOS) may play an important role in the pathogenesis of atherosclerosis. Although fluvastatin has been shown to reduce progression of atherosclerosis, it is not known whether it regulates iNOS expression. We investigated the effects of fluvastatin on iNOS expression and subsequent NO synthesis in vascular smooth muscle cells (VSMCs) and the mechanism by which fluvastatin exerts its effects. Fluvastatin significantly increased interleukin-1ss (IL-1ss)-induced nitrite production by VSMCs in a time-dependent (0 to 24 hours) and dose-dependent (10(-)(8) to 10(-)(5) mol/L) manner. Increased nitrite production by fluvastatin was accompanied by increased iNOS mRNA and protein accumulation. IL-1ss induced nuclear factor-kappaB activation in VSMCs, which was not affected by fluvastatin. Exogenous mevalonate significantly prevented the stimulatory effect of fluvastatin on nitrite production. Cotreatment with geranylgeranyl-pyrophosphate also reversed the effect of fluvastatin. Furthermore, both Rho inhibitor C3 exoenzyme and Rho kinase inhibitor Y-27632 significantly increased IL-1ss-induced nitrite accumulation in VSMCs. These results demonstrated that fluvastatin upregulates iNOS expression and subsequent NO formation in rat VSMCs through inhibition of Rho.

Interaction between monocytes and vascular smooth muscle cells induces expression of hepatocyte growth factor

OBJECTIVE

To investigate the expression of hepatocyte growth factor (HGF)--a multifunctional factor implicated in tissue regeneration, wound healing and angiogenesis--that is induced by cell-to-cell interactions between monocytes and vascular smooth muscle cells (VSMCs), using coculture of human VSMCs and cells of the human monocytoid cell line, THP-1.

METHODS

We collected supernatant from the coculture medium and measured HGF concentrations with an enzyme-linked immunosorbent assay. Northern blot analysis of HGF mRNA was performed using a specific cDNA. To explore which types of cells produce HGF, we performed immunohistochemistry.

RESULTS

Coculture of VSMCs with THP-1 cells for 24 h caused a fivefold increase in HGF concentrations over that in control VSMC culture. Northern blot analysis showed an induction of HGF mRNA in the coculture with a peak at 3 h. Separated cocultures demonstrated that both direct contact and soluble factors contribute to the production of HGF. Immunohistochemistry demonstrated that both types of cells in the coculture produce HGF. Neutralizing antibodies against tumor necrosis factor (TNF)-alpha, interleukin (IL)-1beta and IL-6 inhibited the HGF production in THP-1 cells and VSMCs that was induced by the coculture conditioned medium. The protein kinase C inhibitors H-7, calphostin C and K252b, and the tyrosine kinase inhibitor, genistein, significantly inhibited the production of HGF in the coculture.

CONCLUSIONS

Cell-to-cell interactions between monocytes and VSMCs induced HGF synthesis in both types of cells, suggesting that local HGF production induced by this cell-to-cell interaction has an important role in the pathogenesis of hypertension, atherosclerosis or vascular remodelling.