Jun-ei Obata

Rapid Stabilization of Vulnerable Carotid Plaque Within 1 Month of Pitavastatin Treatment in Patients With Acute Coronary Syndrome

We determined time course of stabilization of echolucent carotid plaques by statin therapy in patients with acute coronary syndrome (ACS). Treatment with 4 mg/d pitavastatin (n = 33) or placebo (n = 32) was initiated within 3 days after onset of ACS in 65 patients with echolucent carotid plaque. Vulnerable carotid plaques were assessed by measuring plaque echolucency using carotid ultrasound with integrated backscatter (IBS) analysis before and 1 month after treatment in all patients. The calibrated IBS value (intima-media IBS value minus adventia IBS) of vulnerable carotid plaques favorably changed at 1 month after treatment in both groups, but the echolucency at 1 month improved more in the pitavastatin than in the placebo group (pitavastatin group: -18.7 ± 3.3 dB at pretreatment versus -12.7 ± 2.3 dB at 1 month *P < 0.001; placebo: -19.0 ± 3.5 dB versus -16.9 ± 3.2 dB, P < 0.05, *P < 0.01 versus the value at 1 month in placebo group). Levels of CRP, VEGF, and TNFα at 1 month were significantly lower in pitavastatin than placebo group. In conclusion, pitavastatin improved carotid plaque echolucency within 1 month of therapy in patients with ACS, in association with decrease in the inflammatory biomarkers related to vulnerable plaques.

Increased gene expression of components of the renin-angiotensin system in glomeruli of genetically hypertensive rats

Objective The renin–angiotensin system (RAS) is implicated in the development of hypertensive glomerulosclerosis. However, no experimental evidence exists that clearly demonstrates activation of glomerular RAS in hypertensive nephropathy. We used stroke-prone spontaneously hypertensive rats (SHRSP) to examine whether RAS components are increased in glomeruli of SHRSP and whether this increase leads to an increase in mRNA levels for transforming growth factor-β1(TGF-β1). Methods We examined the sequential changes of urinary albumin excretion (UAE), morphology, and glomerular mRNA expression for TGF-β1 and fibronectin (FN) in relation to glomerular mRNA expression for angiotensinogen (ATN), angiotensin converting enzyme (ACE), angiotensin II type 1a (AT1a), and type 1b (AT1b) receptors, and intervention with angiotensin II type 1 receptor antagonist candesartan and equihypotensive hydralazine. Results In SHRSP, UAE was normal at 9 weeks of age, but became higher, beginning at 12 weeks of age, than that in the age-matched Wistar–Kyoto (WKY) rats, while SHRSP showed no glomerulosclerosis until 14 weeks of age; it was marked at 24 weeks. Plasma renin activity and plasma angiotensin II level was equivalent in the 9- and 12-week-old SHRSP and the WKY rats; both parameters, however, were elevated in 24-week-old SHRSP as compared with age-matched control. RNase protection assays showed that glomerular levels of ATN, ACE, and AT1a and AT1b receptors mRNA were significantly increased in 9-, 12-, and 14-week-old, but not in 24-week-old SHRSP, compared with age-matched WKY rats. Northern blot analysis showed that glomerular levels of TGF-β1 and FN mRNA were higher in SHRSP than in WKY rats at all time points. Candesartan reduced UAE to control levels, whereas hydralazine reduced UAE but not to control levels. Candesartan administration for 12 weeks virtually prevented the progression of glomerulosclerosis. While candesartan reduced mRNA levels for RAS components, TGF-β1, and FN to control levels, hydralazine was not effective in this respect. Conclusion Results suggest that increases in glomerular RAS components that occur independently of circulating RAS alter glomerular permselectivity and increase the glomerular expression of TGF-β1 and FN in young SHRSP. Findings in old SHRSP suggest that altered glomerular permselectivity and an increased glomerular expression of TGF-β1 and FN may be associated with the activation of systemic RAS. J Hypertens 2000, 18:1247–1255

High plasma levels of macrophage migration inhibitory factor are associated with adverse long-term outcome in patients with stable coronary artery disease and impaired glucose tolerance or type 2 diabetes mellitus

OBJECTIVES MIF is proatherogenic and is highly expressed in unstable atherosclerotic plaques. Circulating levels of MIF are increased in patients with impaired glucose tolerance or type 2 diabetes mellitus (IGT/T2DM). We examined whether high circulating levels of macrophage migration inhibitory factor (MIF) are related to increased risk of future coronary events in patients with coronary artery disease (CAD) and IGT/T2DM. METHODS Plasma MIF levels after overnight fast were measured by ELISA in 617 patients with stable CAD including 79 patients with IGT and 215 patients with T2DM. All patients were prospectively followed for 60 months or until occurrence of one of the coronary events: cardiac death, nonfatal myocardial infarction, unstable angina pectoris requiring coronary revascularization. RESULTS During the follow-up period, an event occurred in 77 (26%) patients with IGT/T2DM and 50 (15%) patients without IGT/T2DM. In patients with IGT/T2DM, higher MIF levels were a significant predictor of coronary events in a multivariate Cox proportional hazards analysis that included the known risk factors, C-reactive protein levels and medication as covariates (HR 3.3, 95% CI 1.6-8.3, p=0.006). The c-statistic showed that the predictive value of MIF levels was incremental over that of the conventional predictors for coronary events (area under ROC curve; 0.70 and 0.61, respectively, p=0.001). In contrast, MIF levels were not significantly related to future coronary events in patients without IGT/T2DM. CONCLUSIONS High MIF levels are an independent risk factor for future coronary events in CAD patients with IGT/T2DM.

Assessment of carotid plaque echolucency in addition to plaque size increases the predictive value of carotid ultrasound for coronary events in patients with coronary artery disease and mild carotid atherosclerosis

OBJECTIVES This study examined whether combined ultrasound assessment of plaque size and echolucency in the carotid artery had an additive effect for predicting coronary events in patients with coronary artery disease (CAD). Ultrasound assessment of either plaque size or echolucency of carotid artery provides prognostic information on coronary events. Combined assessment of plaque size and echolucency of carotid artery has the advantage of obtaining both structural and compositional information in the same artery in a single session. METHODS AND RESULTS Ultrasound assessment of carotid plaque maximum intima-media thickness (plaque-IMTmax) and echolucency with integrated backscatter analysis was performed in 413 patients with CAD and carotid plaque. All study patients were followed up prospectively for 54 months or until the occurrence of a coronary event. During the follow-up period, 49 coronary events occurred including 2 cardiac deaths, 10 non-fatal acute myocardial infarctions and 37 recurrent and refractory unstable angina. Multivariate Cox hazards analysis showed plaque-IMTmax alone (HR 2.01, 95%CI 1.30-3.10), plaque echogenicity alone (HR 0.86, 95%CI 0.80-0.91) and combination of high plaque-IMTmax and low echogenicity on categorical data (HR 2.56, 95%CI 1.39-4.74) were independent predictors of coronary events. Analysis using c-statistics showed that plaque-IMTmax and plaque echolucency in combination had a significant incremental effect on the predictive value of the conventional risk factors for coronary events. CONCLUSIONS Combined ultrasound assessment of carotid plaque size and echolucency has an additive value for prediction of coronary events. Further studies need to evaluate the clinical utility of both ultrasound measurements for risk stratification in CAD.

Predictive value of remnant lipoprotein for cardiovascular events in patients with coronary artery disease after achievement of LDL-cholesterol goals

OBJECTIVES Triglycerides-rich lipoproteins are related to residual cardiovascular risk in patients on lipid-lowering treatment who achieve low-density lipoprotein cholesterol (LDL-C) goals. This study examined the predictive value of remnant lipoprotein levels for cardiovascular events in patients with coronary artery disease (CAD) with LDL-C levels <100mg/dL on lipid-lowering therapy. METHODS Serum levels of remnant lipoproteins (remnant-like lipoprotein particles cholesterol; RLP-C) were measured by an immunoseparation method in 560 patients with CAD who had LDL-C levels <100mg/dL on lipid-lowering therapy, including statin (58%), fibrate (13%) or diet only (29%). All the patients were followed prospectively for a period of ≤ 36 months or until occurrence of one of the following events: cardiac death, non fatal myocardial infarction, unstable angina requiring coronary revascularization, or ischemic stroke. RESULTS During a mean follow-up period of 33 months, 40 events occurred. Stepwise multivariate Cox proportional hazard analysis showed that RLP-C was a significant predictor of cardiovascular events after adjustment for known risk factors and lipid variables including triglycerides, non-high-density lipoprotein (HDL)-C, and total apolipoprotein B (HR 1.53, 95% CI 1.35-1.97, p<0.01). The c-statistics showed that addition of RLP-C had a greater incremental effect on the predictive value of conventional risk factors than addition of non-HDL-C or total apolipoprotein B. CONCLUSIONS RLP-C was superior to non-HDL-C for predicting cardiovascular events in CAD patients with LDL-C levels <100mg/dL on lipid-lowering treatment. Remnant lipoprotein may therefore be an important target for residual risk reduction after LDL-C goals on lipid lowering therapy.

Group V secretory phospholipase A2 plays a pathogenic role in myocardial ischaemia–reperfusion injury

AIMS Group V secretory phospholipase A(2) (sPLA(2)-V) is highly expressed in the heart. This study examined (i) the role of sPLA(2)-V in myocardial ischaemia-reperfusion (I/R) injury and (ii) the cooperative action of sPLA(2)-V and cytosolic PLA(2) (cPLA(2)) in myocardial I/R injury, using sPLA(2)-V knockout (sPLA(2)V(-/-)) mice. METHODS AND RESULTS Myocardial I/R injury was created by 1 h ligation of the left anterior descending coronary artery, followed by 24 h of reperfusion. The sPLA(2)V(-/-) mice had a 44% decrease in myocardial infarct size, a preservation of echocardiographic LV function (%fractional shortening: 40 ± 3.5 vs. 21 ± 4.6, respectively), and lower content of leucotriene B(4) (LTB(4)) and thromboxane B(2) (TXB(2)) (40 and 37% lower, respectively) in the ischaemic myocardium after I/R compared with wild-type (WT) mice. Intraperitoneal administration of AACOCF3 or MAFP, inhibitors of cPLA(2) activity, decreased myocardial infarct size and myocardial content of LTB(4) and TXB(2) in both genotyped mice. The decrease in myocardial infarct size and content of LTB(4) and TXB(2) after cPLA(2) inhibitor administration was greater in WT mice than in sPLA(2)V(-/-) mice. I/R increased phosphorylation of extracellular signal-related kinase 1/2, c-Jun N-terminal kinase, and p38 mitogen-activated protein kinases in the ischaemic myocardium in association with cPLA(2) phosphorylation. The I/R-induced increase in the phosphorylation of p38 and cPLA(2) was less in sPLA(2)-V(-/-) mice than in WT mice. Pretreatment with the p38 inhibitor SB202190 suppressed an increase in cPLA(2) phosphorylation after I/R in WT mice. CONCLUSION sPLA(2)-V plays an important role in the pathogenesis of myocardial I/R injury partly in concert with the activation of cPLA(2).

Deficiency of Phospholipase A2 Receptor Exacerbates Ovalbumin-Induced Lung Inflammation

Secretory phospholipase A2 (sPLA2) plays a critical role in the genesis of lung inflammation through proinflammatory eicosanoids. A previous in vitro experiment showed a possible role of cell surface receptor for sPLA2 (PLA2R) in the clearance of extracellular sPLA2. PLA2R and groups IB and X sPLA2 are expressed in the lung. This study examined a pathogenic role of PLA2R in airway inflammation using PLA2R-deficient (PLA2R−/−) mice. Airway inflammation was induced by immunosensitization with OVA. Compared with wild-type (PLA2R+/+) mice, PLA2R−/− mice had a significantly greater infiltration of inflammatory cells around the airways, higher levels of groups IB and X sPLA2, eicosanoids, and Th2 cytokines, and higher numbers of eosinophils and neutrophils in bronchoalveolar lavage fluid after OVA treatment. In PLA2R−/− mice, intratracheally instilled [125I]-labeled sPLA2-IB was cleared much more slowly from bronchoalveolar lavage fluid compared with PLA2R+/+ mice. The degradation of the instilled [125I]-labeled sPLA2-IB, as assessed by trichloroacetic acid-soluble radioactivity in bronchoalveolar lavage fluid after instillation, was lower in PLA2R−/− mice than in PLA2R+/+ mice. In conclusion, PLA2R deficiency increased sPLA2-IB and -X levels in the lung through their impaired clearance from the lung, leading to exaggeration of lung inflammation induced by OVA treatment in a murine model.

Chronic depletion of glutathione exacerbates ventricular remodelling and dysfunction in the pressure-overloaded heart

AIMS Chronic depletion of myocardial glutathione (GSH) may play a role in cardiac remodelling and dysfunction. This study examined the relationship between chronic GSH depletion and cardiac failure induced by pressure overload in mice lacking the modifier subunit (GCLM) of glutamate-cysteine ligase, the rate-limiting enzyme for GSH synthesis. In addition, we examined the association between idiopathic dilated cardiomyopathy (DCM) in humans and -588C/T polymorphism of the GCLM gene, which reduces plasma levels of GSH. METHODS AND RESULTS Pressure overload in mice was created by transverse aortic constriction (TAC). Myocardial GSH levels after TAC in GCLM(-/-) mice were 31% of those in GCLM(+/+) mice. TAC resulted in greater heart and lung-weight-to-body-weight ratios, greater dilation and dysfunction of left ventricle, more extensive myocardial fibrosis, and worse survival in GCLM(-/-) than GCLM(+/+) mice. Supplementation of GSH diethyl ester reversed the left-ventricular dilation and contractile dysfunction and the increased myocardial fibrosis after TAC in GCLM(-/-) mice. The prevalence of -588T polymorphism of the GCLM gene was significantly higher in DCM patients (n = 205) than in age- and sex-matched control subjects (n = 253) (36 vs. 19%, respectively, P < 0.001). The -588T polymorphism increased the risk of DCM that was independent of age, diabetes, and systolic blood pressure (OR 3.13, 95% CI: 2.28-4.44; P < 0.0001). CONCLUSION Chronic depletion of GSH exacerbates remodelling and dysfunction in the pressure-overloaded heart. The clinical relevance of this mouse model is supported by a significant association between -588T polymorphism of the GCLM gene and patients with DCM.

A comparison of the efficacy of combined ezetimibe and statin therapy with doubling of statin dose in patients with remnant lipoproteinemia on previous statin therapy.

BACKGROUND AND PURPOSE It remains undetermined whether the addition of ezetimibe to ongoing statin therapy is more effective than increasing the dose of statin for reducing remnant lipoprotein levels in patients with remnant lipoproteinemia on previous statin treatment. This study examined whether combined ezetimibe and statin therapy resulted in a greater improvement in remnant lipoprotein levels and endothelial function than with the dose of statin in patients with remnant lipoproteinemia on previous statin treatment. METHODS AND RESULTS A total of 63 patients with stable coronary artery disease and high levels of remnant-like lipoprotein particle cholesterol (RLP-C) (≥5.0 mg/dL) on statin treatment were assigned randomly to two groups and treated with either addition of ezetimibe (10mg/day, n=32) or doubling of statin dose (n=31). The lipid profiles and flow-mediated dilation (FMD) of the brachial artery were measured at enrollment and after 6 months of treatment. Statin and ezetimibe combined therapy reduced RLP-C and improved FMD to a greater extent than doubling the statin dose (% reduction in RLP-C, 48 ± 18% vs. 33 ± 24%, respectively, p=0.01; % improvement in FMD, 47 ± 48% vs. 24 ± 23%, respectively, p=0.02). CONCLUSIONS The addition of ezetimibe to ongoing statin treatment reduced RLP-C levels and improved endothelial dysfunction to a greater extent than doubling the statin dose in patients with high RLP-C levels on previous statin treatment. The present results are preliminary and should be confirmed by further studies on a larger number of study patients.

Mice lacking the glutamate-cysteine ligase modifier subunit are susceptible to myocardial ischaemia–reperfusion injury

AIMS Glutamate-cysteine ligase (GCL), a rate-limiting enzyme for glutathione (GSH) synthesis, is composed of catalytic and modifier subunits. This study examined the pathogenic role of GCL modifier subunits (GCLM) in myocardial ischaemia-reperfusion (I/R) injury using mice lacking the GCLM (GCLM(-/-)). METHODS AND RESULTS The GCLM(-/-)mice had an increase in myocardial I/R injury and apoptosis in ischaemic myocardium compared with GCLM(+/+) mice. There was a decrease in mitochondrial glutathione (GSH) levels in ischaemic myocardium that was more pronounced in GCLM(-/-) mice than in GCLM(+/+) mice (12 vs. 55% of baseline GCLM(+/+), respectively). The ESR signal intensity of the dimethyl-1-pyrroline-N-oxide-hydroxyl radical adducts in ischaemic myocardium was higher in GCLM(-/-) mice than in GCLM(+/+) mice. Hypoxia-reoxygenation induced greater mitochondrial damage in cultured cardiomyocytes from GCLM(-/-) mice than from GCLM(+/+) mice, as evidenced by a reduced membrane potential and increased protein carbonyl content in isolated mitochondria, together with enhanced cytochrome c translocation into the cytosol. Administration of GSH ethyl-ester attenuated myocardial I/R injury and reversed the mitochondrial damage in parallel with the mitochondrial GSH restoration in the myocardium or the cardiomyocytes of GCLM(-/-) mice. CONCLUSION GCLM(-/-) mice were susceptible to myocardial I/R injury partly through an increased vulnerability of mitochondria to oxidative damage owing to mitochondrial GSH reduction.