Tomonori Itoh

Deletion polymorphism of the angiotensin I-converting enzyme gene is associated with serum ACE concentration and increased risk for CAD in the Japanese.

BACKGROUND The angiotensin I-converting enzyme (ACE) is a key component of the renin-angiotensin system thought to be important in the pathogenesis of hypertension and cardiovascular disease. Deletion polymorphism in the ACE gene may be a risk factor for myocardial infarction in the Caucasian population. However, this finding has not yet been investigated in the Japanese population. METHODS AND RESULTS A 287-bp insertion/deletion polymorphism in intron 16 of the ACE gene was examined by polymerase chain reaction in a cross-sectional study of 100 healthy subjects and 178 patients with coronary artery disease (CAD) (70 angina pectoris, 108 myocardial infarction), whose serum ACE levels were concomitantly measured. Polymorphism of the ACE gene was characterized by three genotypes: two deletion alleles (genotype DD), two insertion alleles (genotype II), and heterozygous alleles (genotype ID). No differences could be detected among the three genotypes for total cholesterol, HDL cholesterol, and body mass index. Serum ACE levels were 11.4 +/- 2.7, 14.5 +/- 3.5, and 16.6 +/- 4.6 IU/mL for genotypes II, ID, and DD, respectively. In the study population, the genotype DD was more closely associated with CAD than the other two genotypes (ID and II). The frequency of deletion alleles was higher (0.58) in the CAD group than in healthy control subjects (0.42) (P < .05). Furthermore, multivessel disease was more strongly associated with deletion alleles than with insertion alleles (P < .05). CONCLUSIONS A deletion polymorphism of the ACE gene is associated with serum ACE activity and increased risk for CAD in the Japanese.

In vivo diagnosis of plaque erosion and calcified nodule in patients with acute coronary syndrome by intravascular optical coherence tomography.

OBJECTIVES The aim of this study was to characterize the morphological features of plaque erosion and calcified nodule in patients with acute coronary syndrome (ACS) by optical coherence tomography (OCT). BACKGROUND Plaque erosion and calcified nodule have not been systematically investigated in vivo. METHODS A total of 126 patients with ACS who had undergone pre-intervention OCT imaging were included. The culprit lesions were classified as plaque rupture (PR), erosion (OCT-erosion), calcified nodule (OCT-CN), or with a new set of diagnostic criteria for OCT. RESULTS The incidences of PR, OCT-erosion, and OCT-CN were 43.7%, 31.0%, and 7.9%, respectively. Patients with OCT-erosion were the youngest, compared with those with PR and OCT-CN (53.8 ± 13.1 years vs. 60.6 ± 11.5 years, 65.1 ± 5.0 years, p = 0.005). Compared with patients with PR, presentation with non-ST-segment elevation ACS was more common in patients with OCT-erosion (61.5% vs. 29.1%, p = 0.008) and OCT-CN (100% vs. 29.1%, p < 0.001). The OCT-erosion had a lower frequency of lipid plaque (43.6% vs. 100%, p < 0.001), thicker fibrous cap (169.3 ± 99.1 μm vs. 60.4 ± 16.6 μm, p < 0.001), and smaller lipid arc (202.8 ± 73.6° vs. 275.8 ± 60.4°, p < 0.001) than PR. The diameter stenosis was least severe in OCT-erosion, followed by OCT-CN and PR (55.4 ± 14.7% vs. 66.1 ± 13.5% vs. 68.8 ± 12.9%, p < 0.001). CONCLUSIONS Optical coherence tomography is a promising modality for identifying OCT-erosion and OCT-CN in vivo. The OCT-erosion is a frequent finding in patients with ACS, especially in those with non-ST-segment elevation ACS and younger patients. The OCT-CN is the least common etiology for ACS and is more common in older patients. (The Massachusetts General Hospital Optical Coherence Tomography Registry; NCT01110538).

Effect of atorvastatin on microRNA 221 / 222 expression in endothelial progenitor cells obtained from patients with coronary artery disease.

Background  Endothelial progenitor cells (EPCs) play an important role in the maintenance of vascular integrity. Lipid lowering therapy (LLT) with statins may contribute to biologically relevant activities including the proliferation of endothelial cells. The physiological role of microRNA (miR)‐221/222, a newly discovered class of small RNA, is closely linked to the proliferation of endothelial cells. We therefore investigated whether LLT with statins might affect miR‐221/222 expression in EPCs obtained from patients with coronary artery disease (CAD).

Expression of miR-146a/b is associated with the Toll-like receptor 4 signal in coronary artery disease: effect of renin–angiotensin system blockade and statins on miRNA-146a/b and Toll-like receptor 4 levels

The TLR4 (Toll-like receptor 4) signal plays an important role in immunity in CAD (coronary artery disease). miR-146a/b (where miR is microRNA) regulates the TLR4 downstream molecules IRAK1 (interleukin-1-receptor-associated kinase 1) and TRAF6 (tumour-necrosis-factor-receptor-associated factor 6). It has also been reported that statins and RAS (renin-angiotensin system) inhibition and have anti-atherosclerotic properties. In the present study, we have investigated whether miR-146a/b was expressed with the TLR4 signal in CAD patients, and whether combined treatment with a statin and RAS inhibition might affect these levels. A total of 66 patients with CAD and 33 subjects without CAD (non-CAD) were enrolled. Patients with CAD were randomized to 12 months of combined treatment with atorvastatin and telmisartan [an ARB (angiotensin II receptor blocker)] or atorvastatin and enalapril [an ACEI (angiotensin-converting enzyme inhibitor)]. PBMCs (peripheral blood mononuclear cells) were obtained from peripheral blood at baseline and after 12 months. Levels of miR-146a/b, IRAK1 mRNA, TRAF6 mRNA and TLR4 mRNA/TLR4 protein were significantly higher in the CAD group than in the non-CAD group (all P<0.01). Levels of miR-146a/b were positively correlated with IRAK1 mRNA and TRAF6 mRNA levels. After 12 months of treatment, these levels were markedly decreased in the ARB and ACEI groups, with the decrease in the ARB group being greater than that in the ACEI group (all P<0.05). In our 12-month follow-up study, high levels of miR-146a and TLR4 mRNA/TLR4 protein at baseline were independent predictors of cardiac events. The present study demonstrates that combined treatment with an ARB and a statin decreases miR-146a/b and the TLR4 signal in CAD patients, possibly contributing to the anti-atherogenic effects of ARBs and statins in this disorder.

Local expression of Toll-like receptor 4 at the site of ruptured plaques in patients with acute myocardial infarction

Several reports suggest that a chronic inflammatory process plays a key role in coronary artery plaque instability and subsequent occlusive thrombosis. In a previous study, we found that TLR4 (Toll-like receptor 4) mediates the synthesis of cytokines in circulating monocytes of patients with AMI (acute myocardial infarction); however, it remains unclear whether TLRs are expressed at the site of the ruptured plaque in these patients. The aim of the present study was to determine whether TLR2 and TLR4 are expressed at the site of ruptured plaques in patients with AMI and to compare this with systemic levels. The study included 62 patients with AMI, 20 patients with SA (stable angina) and 32 subjects with a normal coronary angiogram (control). Local samples from the site of the ruptured plaque were taken from patients with AMI using aspiration catheterization. Systemic blood samples from the aorta were taken from patients with AMI and SA and controls. Systemic levels of TLR2 and TLR4 were higher in patients with AMI than in patients with SA and controls. In patients with AMI, local TLR4 levels were higher than systemic levels. There was no significant difference in TLR2 levels between local and systemic samples. TLR4 immunostaining was positive in infiltrating macrophages in ruptured plaque material. Cardiac events were observed in 16 patients with AMI at the time of the 6-month follow-up study. Local and systemic levels of TLR4 were higher in patients with AMI with cardiac events than in those without. These results indicate an increase in monocytic TLR4 expression not only in the systemic circulation, but also at the site of plaque rupture. In conclusion, expression of both systemic and local plaque TLR4 may be one of the mechanisms responsible for the pathogenesis of AMI.

Effect of intensive lipid-lowering therapy on telomere erosion in endothelial progenitor cells obtained from patients with coronary artery disease

Telomere erosion of EPCs (endothelial progenitor cells) may be a key factor in endothelial cell senescence and is highly dependent on cellular oxidative damage. The aim of the present study was to investigate whether LLT (lipid-lowering therapy) with statins could attenuate EPC telomere erosion in patients with CAD (coronary artery disease). The study included 100 patients with stable CAD and 25 subjects without CAD as controls. CAD patients were randomized to 12 months of intensive LLT with atorvastatin or moderate LLT with pravastatin. EPCs were obtained from peripheral blood at baseline and after 12 months of statin therapy. Telomere length in EPCs was measured by FISH (fluorescence in situ hybridization) and oxidative DNA damage by flow cytometry of oxidized DNA bases. EPC telomere length was shorter in the CAD group than in the controls, and oxidative DNA damage to EPCs was higher in the CAD group compared with controls. After 12 months of therapy, changes in lipid profiles were greater in the intensive LLT group than in the moderate LLT group. Intensive LLT markedly increased EPC number and decreased oxidative DNA damage in EPCs (both P<0.05), with no change in telomere length. In contrast, moderate LLT did not change EPC counts or oxidative DNA damage, but showed telomere shortening (P<0.05). There was a weak negative correlation between changes in EPC number and LDL (low-density lipoprotein)-cholesterol levels after intensive LLT, whereas there was no correlation between them after moderate LLT. With in vitro culturing of EPCs subjected to oxidative stress, atorvastatin led to the prevention of EPC telomere shortening compared with pravastatin. In conclusion, the present study has demonstrated that intensive LLT may prevent EPC telomere erosion in patients with CAD, possibly contributing to the beneficial effects of intensive LLT in this disorder.

Cellular and molecular mechanisms of statins: an update on pleiotropic effects.

Coronary artery disease (CAD) is the leading cause of death worldwide. The efficacy and safety of statins (3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors) in primary and secondary prevention of CAD are confirmed in several large studies. It is well known that statins have some pleiotropic, anti-atherosclerotic effects. We review the molecular mechanisms underlying the beneficial effects of statins revealed in recently published studies. Endothelial cell injury is regarded as the classic stimulus for the development of atherosclerotic lesions. In addition, the inflammatory process plays an important role in the aetiology of atherosclerosis. In particular, chronic inflammation plays a key role in coronary artery plaque instability and subsequent occlusive thrombosis. Our previous reports and others have demonstrated beneficial effects of statins on endothelial dysfunction and chronic inflammation in CAD. A better understanding of the molecular mechanism underlying the effectiveness of statins against atherosclerosis may provide a novel therapeutic agent for the treatment of coronary atherosclerosis. The present review summarizes the cellular and molecular mechanism of statins against coronary atherosclerosis.

Expression of let-7i is associated with Toll-like receptor 4 signal in coronary artery disease: Effect of statins on let-7i and Toll-like receptor 4 signal

Toll-like receptor (TLR) 4 signal plays an important role in immunity in coronary artery disease (CAD). A recent report has demonstrated that one of the let-7 family microRNAs, let-7i, directly regulates Toll-like receptor 4 (TLR4) expression and contributes to immune response. The aim of this study was to determine whether let-7i is expressed with TLR4 in patients with CAD, and whether statins (atorvastatin or rosuvastatin) might affect these levels. To determine the effects of let-7i on TLR4 expression, human THP-1 cells transfected with let-7i were analyzed for TLR4 levels. This study included 98 patients with CAD and 48 subjects without CAD (non-CAD). Patients with CAD were randomized to 12 months of treatment with atorvastatin or rosuvastatin. Monocytes were obtained from peripheral blood at baseline and after 12 months of each type of therapy. Levels of let-7i and TLR4 were measured by real-time RT-PCR and FACS. Functional approaches to let-7i showed that transfection of let-7i into human THP-1 cells resulted in regulation of TLR4 expression. Levels of let-7i were lower in the CAD group than in the non-CAD group (0.98±0.42 vs. 4.65±1.21, P<0.01). There was a negative correlation between let-7i and TLR4 levels in patients with CAD (let-7i vs. TLR4 mRNA: r=-0.60, P<0.01; let-7i vs. TLR4 MFI: r=-0.32, P<0.01). The atorvastatin group had markedly increased let-7i levels and diminished TLR4 levels (all P<0.01), whereas the rosuvastatin group showed no change in these levels. This study suggests that atorvastatin down-regulates TLR4 signal via let-7i expression in CAD patients, possibly contributing to the beneficial effects of atorvastatin on let-7i-mediated TLR4 signal in this disorder.

Estradiol-17β regulates the induction of VCAM-1 mRNA expression by interleukin-1β in human umbilical vein endothelial cells

Abstract We examined the effect of estradiol-17β on the expression of vascular cell adhesion molecule-1 (VCAM-1), an adhesion molecule, in human umbilical vascular endothelial cells. After preincubation with estradiol-17β for 24 hours, cells were treated for 4 h with 0.5 μg/ml recombinant human interleukin-1β. The RNase protection assay was performed using an [α-32P]-labeled 121 base pair VCAM-1 cRNA probe. Preincubation with estradiol-17β (250 or 500 pg/ml) suppressed the induction of VCAM-1 mRNA expression by interleukin-1β. VCAM-1 staining with a monoclonal antibody decreased when cells were incubated with estradiol-17β at 250 and 500 pg/ml, while staining was detectable when cells were treated with interleukin-1β at 0.5 μg/ml. In conclusion, estradiol-17β regulates the induction of VCAM-1 gene expression by interleukin-1β in human umbilical vein endothelial cells.

The expression of TNF-α converting enzyme at the site of ruptured plaques in patients with acute myocardial infarction

Background  Tumour necrosis factor‐α (TNF‐α) converting enzyme (TACE) plays an essential role in the TNF‐α shedding process, which could affect the outcome of acute myocardial infarction (AMI). However, it remains unclear whether it originates from the ruptured plaque or represents a systemic process. This study analysed TACE‐mediated TNF‐α shedding at the site of ruptured plaques in AMI patients and compared them with a systemic mechanism.