Takeshi Soeki

Epicardial Adipose Tissue Volume and Adipocytokine Imbalance Are Strongly Linked to Human Coronary Atherosclerosis

Objective—The impact of epicardial adipose tissue (EAT) over abdominal or overall adiposity on coronary artery disease (CAD) is currently unknown. We compared the association among EAT volume (EATV), cytokine/adipocytokine profiles in EAT and subcutaneous fat, and atherogenic CAD. Approach and Results—Paired samples were obtained from EAT and subcutaneous adipose tissue during elective cardiac surgery for CAD (n=50) or non-CAD (n=50). EATV was the sum of cross-sectional EAT areas, and visceral and subcutaneous fat areas were determined at the umbilicus level on computed tomography scans. CD68+, CD11c+, and CD206+ cells were counted using immunohistochemical staining. Cytokine/adipocytokine expression was evaluated using quantitative real-time polymerase chain reaction. Multivariate analysis indicated that male sex, age, diabetes mellitus, high triglycerides, and low high-density lipoprotein cholesterol, and EATV index (EATV/body surface area, cm3/m2) were significant CAD predictors (corrected R2=0.401; P<0.001); visceral fat area, hypertension, smoking, low-density lipoprotein cholesterol (140 mg/dL [3.63 mmol/L]) or statin use were not predictors. The EATV index positively correlated with the CD68+ and CD11c+ cell numbers and nucleotide-binding domain, leucine-rich–containing family, pyrin domain–containing-3 (NLRP3), interleukin-1&bgr;, and interleukin-1R expression; and negatively correlated with adiponectin expression in EAT. A multivariate analysis model, including CD68+ cells and interleukin-1&bgr;, and adiponectin expression in EAT strongly predicted CAD (corrected R2=0.756; P<0.001). Conclusions—EATV and macrophage and cytokine/adipocytokine signals in EAT strongly correlated with CAD. Our findings suggest that EATV and adipocytokine imbalance are strongly linked to human coronary atherosclerosis.

Serial Changes in Serum VEGF and HGF in Patients with Acute Myocardial Infarction

The time course of vascular endothelial growth factor (VEGF) and hepatocyte growth factor (HGF) release in patients with acute myocardial infarction (AMI) is unknown. Blood samples were obtained at the time of admission and 3, 7, 14 and 21 days later in 32 patients with AMI and 30 control patients. Serum VEGF and HGF, as well as C-reactive protein (CRP) and amyloid A protein (SAA), were determined. Both serum VEGF and HGF levels on admission in patients with AMI were higher than control values and peaked on day 7. VEGF levels in patients with preinfarction angina were higher than in patients with no preinfarction angina, whereas the HGF level did not differ. Both CRP and SAA levels peaked on day 3, and the CRP level on day 3 correlate with both VEGF and HGF levels on day 7. We hypothesized that the serum VEGF level is associated with preinfarction ischemia and the increase in VEGF and HGF on day 7 of AMI may represent a response to acute inflammation.

Calcineurin–Nuclear Factor of Activated T Cells Pathway–Dependent Cardiac Remodeling in Mice Deficient in Guanylyl Cyclase A, a Receptor for Atrial and Brain Natriuretic Peptides

Background—Although disruption of guanylyl cyclase (GC) A, a natriuretic peptide receptor, induces cardiac hypertrophy and fibrosis, the molecular mechanism underlying these effects are not well understood. In this study, we examined the role of calcineurin, a calcium-dependent phosphatase, in cardiac remodeling in GCA-knockout (GCA-KO) mice. Methods and Results—At 14 weeks of age, calcineurin activity, nuclear translocation of nuclear factor of activated T cells c3 (NFATc3), and modulatory calcineurin-interacting protein 1 (MCIP1) gene expressions were increased in the hearts of GCA-KO mice compared with wild-type (WT) mice. Blockade of calcineurin activation by FK506 (6 mg/kg body weight administered subcutaneously once a day from 10 to 14 weeks of age) significantly decreased the heart-to-body weight ratio, cardiomyocyte size, and collagen volume fraction in GCA-KO mice, whereas FK506 did not affect these parameters in WT mice. Overexpression of atrial and brain natriuretic peptides, collagen, and fibronectin mRNAs in GCA-KO mice was also attenuated by FK506. Electrophoretic mobility shift assays demonstrated that GATA4 DNA-binding activity was increased in GCA-KO mice, and this increase was inhibited by calcineurin blockade. In neonatal cultured cardiac myocytes, inhibition of GCA by HS142-1 (100 &mgr;g/mL) increased basal and phenylephrine (10−6 mol/L)-stimulated calcineurin activity, nuclear translocation of NFATc3, and MCIP1 mRNA expression. In contrast, activation of GCA by atrial natriuretic peptide (10−6 mol/L) inhibited phenylephrine (10−6 mol/L)-stimulated nuclear translocation of NFATc3. Conclusions—These results suggest that activation of cardiac GCA by locally secreted natriuretic peptides protects the heart from excessive cardiac remodeling by inhibiting the calcineurin-NFAT pathway.

Obesity-induced DNA released from adipocytes stimulates chronic adipose tissue inflammation and insulin resistance.

DNA released from obesity-induced degenerated adipocytes stimulates inflammation in adipose tissue and insulin resistance. Obesity stimulates chronic inflammation in adipose tissue, which is associated with insulin resistance, although the underlying mechanism remains largely unknown. Here we showed that obesity-related adipocyte degeneration causes release of cell-free DNA (cfDNA), which promotes macrophage accumulation in adipose tissue via Toll-like receptor 9 (TLR9), originally known as a sensor of exogenous DNA fragments. Fat-fed obese wild-type mice showed increased release of cfDNA, as determined by the concentrations of single-stranded DNA (ssDNA) and double-stranded DNA (dsDNA) in plasma. cfDNA released from degenerated adipocytes promoted monocyte chemoattractant protein-1 (MCP-1) expression in wild-type macrophages, but not in TLR9-deficient (Tlr9−/−) macrophages. Fat-fed Tlr9−/− mice demonstrated reduced macrophage accumulation and inflammation in adipose tissue and better insulin sensitivity compared with wild-type mice, whereas bone marrow reconstitution with wild-type bone marrow restored the attenuation of insulin resistance observed in fat-fed Tlr9−/− mice. Administration of a TLR9 inhibitory oligonucleotide to fat-fed wild-type mice reduced the accumulation of macrophages in adipose tissue and improved insulin resistance. Furthermore, in humans, plasma ssDNA level was significantly higher in patients with computed tomography–determined visceral obesity and was associated with homeostasis model assessment of insulin resistance (HOMA-IR), which is the index of insulin resistance. Our study may provide a novel mechanism for the development of sterile inflammation in adipose tissue and a potential therapeutic target for insulin resistance.

Endothelial Nitric Oxide Synthase–Independent Protective Action of Statin Against Angiotensin II–Induced Atrial Remodeling via Reduced Oxidant Injury

Activation of the renin-angiotensin system exacerbates atrial remodeling, leading to atrial fibrillation and thrombosis, especially in a condition with decreased NO bioavailability. Recently, it has been reported that statins reduce the incidence of atrial fibrillation through attenuation of atrial remodeling; however, the mechanisms have not been completely elucidated. Therefore, we aimed to clarify the beneficial effect of statin on atrial remodeling in condition with reduced NO bioavailability. Endothelial NO synthase−/− mice were sham operated or infused with angiotensin II (Ang II) via an osmotic minipump for 2 weeks, and Ang II–infused mice were divided into 3 treatment groups: pitavastatin, Tempol (a free radical scavenger), or vehicle. Echocardiography and electrocardiography showed that Ang II infusion caused left atrial enlargement and a high incidence of atrial fibrillation, whereas pitavastatin and Tempol prevented these abnormalities. In histological analysis, Ang II–induced atrial interstitial fibrosis, perivascular fibrosis, and cardiomyocyte hypertrophy were all attenuated by pitavastatin and Tempol. Immunohistochemical staining showed that Ang II downregulated thrombomodulin and tissue factor pathway inhibitor and upregulated tissue factor and plasminogen activator inhibitor 1 in the left atrium and that pitavastatin and Tempol corrected the thrombogenic condition. Moreover, pitavastatin and Tempol reduced Ang II–induced atrial superoxide production and atrial transforming growth factor-&bgr;1 expression and Smad 2/3 phosphorylation. Atrial rac1-GTPase activity, known to activate NADPH oxidase, was attenuated by pitavastatin but not by Tempol. In conclusion, pitavastatin exerts endothelial NO synthase–independent protective actions against Ang II–induced atrial remodeling and atrial fibrillation with enhanced thrombogenicity through suppression of oxidant injury.

Rivaroxaban, a novel oral anticoagulant, attenuates atherosclerotic plaque progression and destabilization in ApoE-deficient mice

OBJECTIVE Activated factor X (FXa) plays a key role in the coagulation cascade, whereas accumulating evidence suggests that it also contributes to the pathophysiology of chronic inflammation on the vasculature. In this study, we assessed the hypothesis that rivaroxaban (Riv), a direct FXa inhibitor, inhibits atherogenesis by reducing macrophage activation. METHODS AND RESULTS Expression levels of PAR-1 and PAR-2, receptors for FXa, increased in the aorta of apolipoprotein E-deficient (ApoE(-/-)) mice compared with wild-type mice (P < 0.01, P < 0.05, respectively). Administration of Riv (5 mg/kg/day) for 20 weeks to 8-week-old ApoE(-/-) mice reduced atherosclerotic lesion progression in the aortic arch as determined by en-face Sudan IV staining compared with the non-treated group (P < 0.05) without alteration of plasma lipid levels and blood pressure. Histological analyses demonstrated that Riv significantly decreased lipid deposition, collagen loss, macrophage accumulation and matrix metallopeptidase-9 (MMP-9) expression in atherosclerotic plaques in the aortic root. Quantitative RT-PCR analyses using abdominal aorta revealed that Riv significantly reduced mRNA expression of inflammatory molecules, such as MMP-9, tumor necrosis factor-α (TNF-α). In vitro experiments using mouse peritoneal macrophages or murine macrophage cell line RAW264.7 demonstrated that FXa increased mRNA expression of inflammatory molecules (e.g., interleukin (IL)-1β and TNF-α), which was blocked in the presence of Riv. CONCLUSIONS Riv attenuates atherosclerotic plaque progression and destabilization in ApoE(-/-) mice, at least in part by inhibiting pro-inflammatory activation of macrophages. These results indicate that Riv may be particularly beneficial for the management of atherosclerotic diseases, in addition to its antithrombotic activity.

Index-Beat Assessment of Left Ventricular Systolic and Diastolic Function during Atrial Fibrillation Using Myocardial Strain and Strain Rate

BACKGROUND Accurate assessment of left ventricular (LV) function in patients with atrial fibrillation (AF) remains difficult, mainly because of the beat-to-beat variability of many echocardiographic parameters. The aim of this study was to assess the hypothesis that LV function can be estimated from an index-beat echocardiographic assessment in patients with AF using myocardial strain and strain rate. METHODS A prospective study was conducted to assess 25 patients with AF (mean age, 66 ± 10 years). Peak systolic longitudinal strain (LS) and peak diastolic longitudinal strain rate (dSR) were measured using two different methods: (1) mean LS and dSR, the averages of instantaneous LS and dSR over 10 sec, and (2) index-beat LS and dSR, calculated when the ratio of the preceding (RR1) to the pre-preceding (RR2) interval was 1 (range, 0.96-1.04). These variables were compared with simultaneously measured LV pressure parameters using Millar catheters. RESULTS There was a positive linear relationship between mean LS and index-beat LS at RR1/RR2 = 1 (r = 0.94, P < .001) and a positive linear relationship between mean dSR and index-beat dSR (r = 0.69, P < .001). Index-beat LS was correlated with the maximal positive derivative of LV pressure (peak +dP/dt) (r = -0.73, P < .001). Index-beat dSR was correlated with the time constant of isovolumic LV pressure decay (τ) (r = -0.63, P < .001). To investigate the independent predictors of τ, a stepwise multilinear regression analysis showed that index-beat dSR was the best predictor of τ. CONCLUSIONS Index-beat parameters accurately reflect the mean values of parameters in patients with AF. These noninvasively obtained index-beat parameters are useful to assess surrogate LV function even in patients with AF.

Role of circulating vascular endothelial growth factor and hepatocyte growth factor in patients with coronary artery disease

Abstract Vascular endothelial growth factor (VEGF) and hepatocyte growth factor (HGF) are thought to stimulate endothelial cell proliferation and induce angiogenesis in vivo. However, the precise mechanism responsible for VEGF and HGF release in patients with coronary artery disease is still unknown. We studied serum concentrations of VEGF and HGF in 20 patients with acute myocardial infarction (AMI), 20 patients with stable angina pectoris (AP) who had reversible perfusion defects on stress myocardial scintigraphy, and 16 patients with old myocardial infarction (OMI) who had no reversible defects on stress myocardial scintigraphy. The control group consisted of 20 patients with atypical chest pain who had angiographically normal coronary arteries. Serum VEGF and HGF concentrations were measured by enzyme-linked immunosorbent assay. Both the serum VEGF and HGF concentrations in the early stage of myocardial infarction in the patients with AMI were higher than those in the patients with AP and with OMI, and control patients. The VEGF concentration in the patients with AP was higher than in the patients with OMI, whereas the HGF concentration did not differ in the patients with AP and OMI. The VEGF concentration in AMI patients who had had preinfarction angina on admission was higher than that of patients who had had no preinfarction angina, whereas the HGF concentration did not differ between the two groups of patients. These results suggest that the serum VEGF concentration may reflect myocardial ischemia to a greater degree than the serum HGF concentration.

Elevated concentrations of pentraxin 3 are associated with coronary plaque vulnerability

BACKGROUND Inflammation is a critical contributing factor to the development and progression of atherosclerosis. Pentraxin 3 (PTX3) is produced abundantly in atherosclerotic lesions while C-reactive protein (CRP) is mainly produced in the liver. In this study, we investigated whether plasma levels of PTX3 might be a sensitive marker both for the severity of coronary artery disease and vulnerable plaques. Next, we determined whether assays for inflammatory molecules can be used to monitor the therapeutic effects of telmisartan on stabilization of vulnerable atherosclerotic plaques. METHODS AND RESULTS We measured PTX3 concentrations in the peripheral and coronary sinus plasma of 40 patients with angina pectoris (AP) and 20 control subjects. Next, in 28 patients with AP, we determined the correlation between levels of inflammatory molecules and the computed tomography (CT) density of plaques as a quantitative index of plaque vulnerability. There was no significant difference in peripheral plasma PTX3 concentrations between patients with AP and control subjects, while coronary sinus plasma PTX3 concentrations were significantly higher in AP patients than control subjects. The concentrations of PTX3 in coronary sinus and peripheral plasma correlated with Gensini scores as an index of severity of coronary atherosclerosis. Interestingly, there was a significantly negative correlation between plasma PTX3 concentrations and CT density (r=-0.67, p<0.01). On the other hand, CT density did not correlate with the peripheral plasma concentrations of monocyte chemoattractant protein-1 (MCP-1) or high-sensitivity CRP (hsCRP). Furthermore, telmisartan treatment for 6 months decreased plasma concentrations of PTX3 but not those of MCP-1 or hsCRP in 12 patients with essential hypertension. Multivariate regression analysis revealed that changes in PTX3 levels were independent of blood pressure changes. CONCLUSIONS PTX3 is likely more specific than hsCRP as an indicator of coronary plaque vulnerability that could lead to plaque rupture.

Telmisartan ameliorates insulin sensitivity by activating the AMPK/SIRT1 pathway in skeletal muscle of obese db/db mice

BackgroundTelmisartan is a well-established angiotensin II type 1 receptor blocker that improves insulin sensitivity in animal models of obesity and insulin resistance, as well as in humans. Telmisartan has been reported to function as a partial agonist of the peroxisome proliferator-activated receptor (PPAR) γ, which is also targeted by the nicotinamide adenine dinucleotide (NAD)-dependent deacetylase (SIRT1). Here, we investigated the pathways through which telmisartan acts on skeletal muscle, in vitro as well as in vivo.MethodsNine-week-old male db/db mice were fed a 60% high-fat diet, with orally administrated either vehicle (carboxymethyl-cellulose, CMC), 5 mg/kg telmisartan, or 5 mg/kg telmisartan and 1 mg/kg GW9662, a selective irreversible antagonist of PPARγ, for 5 weeks. Effects of telmisartan on Sirt1 mRNA, AMPK phosphorylation, and NAD+/NADH ratio were determined in C2C12 cultured myocytes.Results and discussionTelmisartan treatment improved insulin sensitivity in obese db/db mice fed a high-fat diet and led to reduction in the size of hypertrophic pancreatic islets in these mice. Moreover, in vitro treatment with telmisartan led to increased expression of Sirt1 mRNA in C2C12 skeletal muscle cells; the increase in Sirt1 mRNA in telmisartan-treated C2C12 myoblasts occurred concomitantly with an increase in AMPK phosphorylation, an increase in NAD+/NADH ratio, and increases in the mRNA levels of PGC1α, FATP1, ACO, and GLUT4.ConclusionsOur results indicate that telmisartan acts through a PPARγ-independent pathway, but at least partially exerts its effects by acting directly on skeletal muscle AMPK/SIRT1 pathways.