BENEFICIAL EFFECTS OF AUTOLOGOUS BONE MARROW MONONUCLEAR CELL TRANSPLANTATION AGAINST ELASTASE-INDUCED EMPHYSEMA IN RABBITS

The authors investigated whether autologous bone marrow mononuclear cell (BMC) transplantation via the left and right main bronchi would mitigate elastase-induced pulmonary emphysema in rabbits. Four weeks after elastase administration, rabbits also receiving BMCs showed significantly better pulmonary function (FVC, FEV100, FEVPEF) and smaller alveolar airspaces, as indicated by a smaller mean linear intercept, than those receiving porcine pancreatic elastase (PPE) (200 U/kg) alone via the left and right main bronchi. BMCs also significantly reduced cell counts in bronchoalveolar lavage fluid, the incidence of apoptotic (TUNEL-positive) cells and matrix metalloproteinase (MMP)-2 expression, while increasing numbers of proliferative (Ki-67-positive) cells. Thus, BMCs may inhibit the progression to emphysema by attenuating inflammation, MMP-2 expression, and apoptosis, while enhancing alveolar cell proliferation.

Unique mode of cell death in freshly isolated adult rat ventricular cardiomyocytes exposed to hydrogen peroxide

To address whether adult rat ventricular cardiomyocytes (ARVCs) exposed to oxidant stress die via apoptosis (secondarily by necrosis) or primarily by necrosis, we exposed ARVCs to hydrogen peroxide (H2O2; 0.1-100 microM) for up to 24 h and then compared them with isoproterenol-induced apoptotic and Triton X-induced necrotic controls. Cellular shrinkage preceded plasma membrane disruption, reflected by trypan blue uptake in ARVCs exposed to lower concentrations of H2O2 (<1 microM; an apoptotic pattern), but the order was reversed in cells exposed to higher concentrations of H2O2 (>1 microM; a necrotic pattern). DNA fragmentation, caspase-3 activation, mitochondrial membrane potential preservation, and ATP preservation were all apparent in ARVCs treated with low H2O2 (0.5 microM), but not in those treated with high H2O2 (10 microM). In addition, electron microscopy revealed unique morphology in H2O2-treated ARVCs; i.e., the nuclei had a homogeneous ground glass-like appearance that was never accompanied by chromatin condensation. Apparently, high concentrations of H2O2 caused primary necrosis in ARVCs, whereas low concentrations induced biochemically comparable apoptosis, although the latter did not satisfy the morphological criteria of apoptosis. These findings caution against the use of oxidant stress, H2O2 in particular, as an inducer of apoptosis in ARVCs.

Functional significance and morphological characterization of starvation-induced autophagy in the adult heart

To examine the functional significance and morphological characteristics of starvation-induced autophagy in the adult heart, we made green fluorescent protein-microtubule-associated protein 1-light chain 3 (LC3) transgenic mice starve for up to 3 days. Electron microscopy revealed round, homogenous, electron-dense lipid droplet-like vacuoles that initially appeared in cardiomyocytes as early as 12 hours after starvation; these vacuoles were identified as lysosomes based on cathepsin D-immunopositive reactivity and acid phosphatase activity. The increase in the number of lysosomes depended on the starvation interval; typical autophagolysosomes with intracellular organelles also appeared, and their numbers increased at the later phases of starvation. Myocardial expression of autophagy-related proteins, LC3-II, cathepsin D, and ubiquitin, increased, whereas both myocardial ATP content and starvation integral decreased. Treatment with bafilomycin A1, an autophagy inhibitor, did not affect cardiac function in normally fed mice but significantly depressed cardiac function and caused significant left ventricular dilatation in mice starved for 3 days. The cardiomyocytes were occupied with markedly accumulated lysosomes in starved mice treated with bafilomycin A1, and both the myocardial amino acid content, which was increased during starvation, and the myocardial ATP content were severely decreased, potentially contributing to cardiac dysfunction. The present findings suggest a critical role of autophagy in the maintenance of cardiac function during starvation in the adult.

Antidiabetic drug pioglitazone protects the heart via activation of PPAR-gamma receptors, PI3-kinase, Akt, and eNOS pathway in a rabbit model of myocardial infarction

The insulin-sensitizing drug pioglitazone has been reported to be protective against myocardial infarction. However, its precise mechanism is unclear. Rabbits underwent 30 min of coronary occlusion followed by 48 h of reperfusion. Rabbits were assigned randomly to nine groups (n = 10 in each): the control group (fed a normal diet), pioglitazone group (fed diets containing 1 mg.kg(-1).day(-1) pioglitazone), pioglitazone + 5-hydroxydecanoic acid (HD) group [fed the pioglitazone diet + 5 mg/kg iv 5-HD, a mitochondrial ATP-sensitive K(+) (K(ATP)) channel blocker], pioglitazone + GW9662 group [fed the pioglitazone diet + 2 mg/kg iv GW9662, a peroxisome proliferator activated receptor (PPAR)-gamma antagonist], GW9662 group (fed a normal diet + iv GW9662), pioglitazone + wortmannin group [fed the pioglitazone diet + 0.6 mg/kg iv wortmannin, a phosphatidylinositol (PI)3-kinase inhibitor], wortmannin group (fed a normal diet + iv wortmannin), pioglitazone + nitro-l-arginine methyl ester (l-NAME) group [fed the pioglitazone diet + 10 mg/kg iv l-NAME, a nitric oxide synthase (NOS) inhibitor], and l-NAME group (fed a normal diet + iv l-NAME). All groups were fed the diets for 7 days. The risk area and nonrisk area of the left ventricle (LV) were separated by Evans blue dye, and the infarct area was determined by triphenyltetrazolium chloride staining. The infarct size was calculated as a percentage of the LV risk area. Western blotting was performed to assess levels of Akt and phospho-Akt and phospho-endothelial NOS (eNOS) in the myocardium following reperfusion. The infarct size was significantly smaller in the pioglitazone group (21 +/- 2%) than in the control group (43 +/- 3%). This effect was abolished by GW9662 (42 +/- 3%), wortmannin (40 +/- 3%), or l-NAME (42 +/- 7%) but not by 5-HD (24 +/- 5%). Western blotting showed higher levels of phospho-Akt and phospho-eNOS in the pioglitazone group. Pioglitazone reduces the myocardial infarct size via activation of PPAR-gamma, PI3-kinase, Akt, and eNOS pathways, but not via opening the mitochondrial K(ATP) channel. Pioglitazone may be a novel strategy for the treatment of diabetes mellitus with coronary artery disease.

Combined therapy with cardioprotective cytokine administration and antiapoptotic gene transfer in postinfarction heart failure

We hypothesized that therapy, composed of antiapoptotic soluble Fas (sFas) gene transfer, combined with administration of the cardioprotective cytokine granulocyte colony-stimulating factor (G-CSF), would markedly mitigate cardiac remodeling and dysfunction following myocardial infarction (MI). On the 3rd day after MI induced by ligating the left coronary artery in mice, four different treatments were initiated: saline injection (Group C, n = 26); G-CSF administration (Group G, n = 27); adenoviral transfer of sFas gene (Group F, n = 26); and the latter two together (Group G+F, n = 26). Four weeks post-MI, Group G+F showed better survival than Group C (96 vs. 65%, P < 0.05) and the best cardiac function among the four groups. In Group G, the infarct scar was smaller and less fibrotic, whereas in Group F the scar was thicker, without a reduction in area, and contained abundant myofibroblasts and vascular cells; Group G+F showed both phenotypes. G-CSF exerted a beneficial effect on infarct tissue dynamics through antifibrotic and proliferative effects on granulation tissue; however, it also exerts an adverse proapoptotic effect that leads to thinning of the infarct scar. sFas appeared to offset the latter drawback. In vitro study using cultured myofibroblasts derived from the infarct tissue revealed that G-CSF increased proliferating activity of those cells accompanying activation of Akt and signal transducer and activator of transcription 3, while accelerating Fas-mediated apoptosis with increasing Bax-to-Bcl-2 ratio. The results suggest that combined use of G-CSF administration and sFas gene therapy is a potentially powerful tool against post-MI heart failure.

Integrated backscatter and intima-media thickness of the thoracic aorta evaluated by transesophageal echocardiography in hypercholesterolemic patients: effect of pitavastatin therapy

The effect of a strong, lipophilic statin (pitavastatin) on the thoracic aorta has not yet been elucidated. The purpose of the present study was to evaluate the effects of pitavastatin (P) therapy on plaque components and morphology in the thoracic aorta by transesophageal echocardiography (TEE) and clarify the impact of the therapy on media and intima in patients with hypercholesterolemia. Sixty-four media and 64 intima of the thoracic aorta were investigated in 32 patients with hypercholesterolemia. The corrected integrated backscatter (c-IBS) values in the thoracic aortic wall and intima-media thickness (IMT) at the same site were measured before and after P therapy or diet (D) for 7 mo. Moreover, c-IBS values in media were measured in 168 patients without hypercholesterolemia to estimate age-dependent changes. C-IBS values in media were correlated with age (r = 0.84, p < 0.001). C-IBS and IMT of media in the P group significantly decreased from -17.8 +/- 2.4 to -20.1 +/- 3.7 dB and from 1.7 +/- 0.3 to 1.5 +/- 0.3 mm, respectively (p < 0.001), whereas those in the D group significantly increased from -18.3 +/- 2.0 to -16.7 +/- 2.1 dB and from 1.6 +/- 0.3 to 1.7 +/- 0.2 mm, respectively (p < 0.001). IMT in intima in the P group significantly decreased from 3.7 +/- 0.4 to 3.3 +/- 0.4 mm (p < 0.001). C-IBS in intima in the P group significantly increased from -10.2 +/- 2.2 to -6.9 +/- 1.7 dB, which indicated plaque stabilization. Pitavastatin improved the atherosis measured by IMT and sclerosis measured by c-IBS values in the media and induced stabilization and regression of plaques in the intima of the thoracic aorta.

Benefits of reperfusion beyond infarct size limitation

The most critical determinant of prognosis in patients with acute myocardial infarction (MI) is infarct magnitude, which can be established within several hours of an attack. The importance of the subsequent healing process is not negligible, however. In fact, much experimental and clinical evidence suggests that late reperfusion of the infarct-related coronary artery--i.e. at times too late to salvage the myocardium within the area at risk-is beneficial for reducing left ventricular remodelling and decreasing mortality ('open artery hypothesis'). For instance, one recent study highlighted the beneficial effects of late reperfusion therapy on the infarct tissue cell dynamics following acute MI. Nonetheless, several recent large, randomized clinical trials have failed to provide evidence of such benefits, refuting the clinical efficacy of late reperfusion. In addition, they also underscore the need for revised clinical studies in which there is less heterogeneity in the timing of reperfusion and in the initial infarct size, as well as the need for sustained patency of the recanalized artery. This review focuses on the effects of late reperfusion on the pathophysiology of MI in the context of the infarct tissue dynamics and clinical outcomes. We also discuss the issues that need to be resolved to improve clinical application.

Fate of isolated adult cardiomyocytes undergoing starvation-induced autophagic degeneration

We induced autophagy in isolated adult rat ventricular cardiomyocytes by incubating them in glucose-free medium supplemented with mannitol for up to 4 days. The upregulation of LC3 and vacuoles containing partially degraded subcellular organelles were readily apparent in glucose-starved cells. Most dead cells in both groups showed features of necrosis, although the survival rate was significantly lower among glucose-starved cells than among the controls. In contrast, the rate of apoptosis was about the same in both groups. Two inhibitors of autophagy, 3-methyladenine (3-MA) and leupeptin, significantly reduced the viability of both control and glucose-starved cells in a dose-dependent manner and caused specific morphological alterations: 3-MA reduced the number of autophagic vacuoles, whereas leupeptin greatly increased their number and size. Conversely, rapamycin, an enhancer of autophagy, improved the survival of glucose-starved cells. The reduction in cellular ATP caused by glucose depletion was exacerbated by the inhibitors but mitigated by rapamycin, suggesting that inhibition of autophagy may accelerate energy depletion, leading to necrosis. Our findings suggest that in cardiomyocytes, autophagy is a compensatory, prosurvival response to stress, and that autophagic death is an unsuccessful outcome brought on by necrosis.

Simvastatin reduces myocardial infarct size via increased nitric oxide production in normocholesterolemic rabbits

OBJECTIVE

Statins have been reported to be protective against myocardial infarction (MI). Moreover, statin drugs upregulate nitric oxide (NO) in coronary artery independent of lipid-lowering effects. However their precise mechanism for MI-protection is unclear. We investigated the effect of lipophilic statin administration in a normocholesterolemic rabbit MI model.

METHODS

Nω-nitro-L-arginine methylester (L-NAME, 10 mg/kg) or vehicle alone was intravenously administered 20 min before inducing ischemia, followed by intravenous administration of simvastatin (5 mg/kg) or saline 10 min before ischemia. Rabbits then underwent 30 min of coronary occlusion followed by 48 h of reperfusion. The at-risk and infarct areas were calculated as a percentage of the total left ventricular slice area.

RESULTS

Determination of infarct size revealed that pre-ischemic treatment with simvastatin reduced infarct size (30.5 ± 4%) in comparison to controls (45.0 ± 3%) (P < 0.05). This infarct size-reducing effect of simvastatin could be completely abrogated by pretreatment with L-NAME (42.0 ± 4%).

CONCLUSIONS

Pre-ischemic treatment with simvastatin reduces MI size via NO production. Simvastatin could be a useful drug for coronary artery disease patients without dyslipidemia as it has direct protective effects.

Tissue characterization of coronary plaques: comparison of integrated backscatter intravascular ultrasound with virtual histology intravascular ultrasound

BACKGROUND

Integrated backscatter (IB) intravascular ultrasound (IVUS) and IVUS Virtual Histology (VH) have been developed for tissue characterization, but have never been compared directly. The purpose of this study was to compare the overall agreement between IB-IVUS and IVUS-VH in the tissue characterization of plaques from the same coronary arterial cross-section.

METHODS AND RESULTS

Images were acquired from 46 coronary arteries from 25 cadavers. Of a total of 392 histology/IVUS image pairs, 152 pairs were diagnosed as Stary's type III, IV, Va, Vb and Vc, and compared for IB-IVUS, IVUS-VH and histology. In the qualitative comparison, the overall agreement between histological and IB-IVUS diagnoses was higher (kappa = 0.81, 95% confidence interval (CI): 0.74-0.89) than that of the IVUS-VH diagnoses (kappa = 0.66, 95%CI: 0.56-0.75). The % fibrosis area determined by IB-IVUS was significantly correlated with the relative area of fibrosis based on histology (r = 0.67, p < 0.001). In the quantitative comparison, the overall agreement between the histological and IB-IVUS diagnoses was higher (kappa = 0.83, 95% CI: 0.75-0.91) than that of the IVUS-VH diagnoses (kappa = 0.73, 95% CI: 0.63-0.83).

CONCLUSION

Based on histology as the gold standard, IB-IVUS provided higher diagnostic accuracy than IVUS-VH for tissue characterization of coronary plaques.

Morphological and biochemical characterization of basal and starvation-induced autophagy in isolated adult rat cardiomyocytes

Autophagy is simultaneously a mode of programmed cell death and an important physiological process for cell survival, but its pathophysiological significance in cardiac myocytes remains largely unknown. We induced autophagy in isolated adult rat ventricular cardiomyocytes (ARVCs) by incubating them in glucose-free, mannitol-supplemented medium for up to 4 days. Ultrastructurally, intracellular vacuoles containing degenerated subcellular organelles (e.g., mitochondria) were markedly apparent in the glucose-starved cells. Microtubule-associated protein-1 light chain 3 was significantly upregulated among the glucose-starved ARVCs than among the controls. After 4 days, glucose-starved ARVCs showed a significantly worse survival rate (19+/-5.2%) than the controls (55+/-8.3%, P<0.005). Most dead ARVCs in both groups showed features of necrosis, and the rate of apoptosis did not differ between the groups. Two inhibitors of autophagy, 3-methyladenine (3-MA) and leupeptin, significantly and dose-dependently reduced the viability of both control and glucose-starved ARVCs and caused specific morphological alterations; 3-MA reduced autophagic findings, whereas leupeptin greatly increased the numbers and the sizes of vacuoles that contained incompletely digested organelles. The knockdown of the autophagy-related genes with small interfering RNA also reduced the glucose-starved ARVCs viability, but rapamycin, an autophagy enhancer, improved it. Reductions in the ATP content of ARVCs caused by glucose depletion were exacerbated by the inhibitors while attenuated by rapamycin, suggesting that autophagy inhibition might accelerate energy depletion, leading to necrosis. Taken together, our findings suggest that autophagy in cardiomyocytes reflects a prosurvival, compensatory response to stress and that autophagic cardiomyocyte death represents an unsuccessful outcome due to necrosis.

Mechanisms by Which Late Coronary Reperfusion Mitigates Postinfarction Cardiac Remodeling

Although recanalization of the infarct-related artery late after myocardial infarction (MI) is known to reduce both cardiac remodeling and mortality, the mechanisms responsible are not yet fully understood. We compared infarcted rat hearts in which the infarct-related coronary artery was opened 24 hours after infarction (late reperfusion [LR] group) with those having a permanently occluded artery. Left ventricular dilatation and dysfunction were significantly mitigated in the LR group 1, 2, and 4 weeks post-MI. Attributable, in large part, to the greater number of cells present, the infarcted wall was significantly thicker in the LR group, which likely reduced wall stress and mitigated cardiac dysfunction. Granulation tissue cell proliferation was increased to a greater degree in the LR group 4 days post-MI, whereas the incidence of apoptosis was significantly lower throughout the subacute stage (4 days, 1 week, and 2 weeks post-MI), further suggesting preservation of granulation tissue cells contributes to the thick, cell-rich scar. Functionally, myocardial debris was more rapidly removed from the infarcted areas in the LR group during subacute stages, and stouter collagen was more rapidly synthesized in those areas. Direct acceleration of Fas-mediated apoptosis by hypoxia was confirmed in vitro using infarct tissue-derived myofibroblasts. In salvaged cardiomyocytes, degenerative changes, but not apoptosis, were mitigated in the LR group, accompanied by restoration of GATA-4 and sarcomeric protein expression. Along with various mechanisms proposed earlier, the present findings appear to provide an additional pathophysiological basis for the benefits of late reperfusion.

Can negative cardiac effect of proton pump inhibitor and high-dose H2-blocker have clinical influence on patients with stable angina?

BACKGROUND

Aspirin and anti-platelet drugs are used commonly for patients with coronary heart disease. Proton pump inhibitor (PPI) and high-dose H2-blocker were recommended for preventing NSAIDs-related ulcer. Previously H2-blocker reported to have some negative cardiovascular effects. Additionally, a recent in vitro study showed that PPI reduced cardiac contractility. In this study, we evaluated whether chronic administration of PPI and high-dose H2-blocker affects left ventricular function.

METHOD

Fifty-two stable angina patients were enrolled and classified into PPI group ([P]; lansoprazole: 15 mg/day, n=28), H2-blocker group ([H]; famotidine: 40 mg/day, n=8), and control ([C]; none or mucosal-defense drug, n=16). Eligible patients showed normal cardiac function in initial catheterization without administrated PPI or H2-blocker. They received percutaneous coronary intervention and follow-up catheterization. We compared changes in ejection fraction (EF: %), end diastolic/systolic volume index (EDVI/ESVI: ml/m(2)), and peak positive/negative dp/dt (+/-dp/dt: mmHg/s) in left ventricular angiography series.

RESULT

There were no significant differences among three groups regarding patient characteristics, backgrounds of angiographic and intervention, except for fewer smokers in [C]. Other drugs such as beta- and Ca-blocker did not have effects on cardiac function except for aspirin during 255+/-115 days follow-up. Rate of EF changes significantly decreased in [P], and tended to decrease in [H] (C: 3.8+/-9.8%, H: -1.6+/-7.6%, P: -2.1+/-5.9%; p<0.05 for [C] vs. [P]). Those of ESVI changes were significantly greater in [P], and tended to be greater in [H] (C: -4.5+/-16.2%, H: 4.9+/-15.5%, P: 7.3+/-16.2%; p<0.05 for [C] vs. [P]), though, EDVI changes' were similar (C: 2.5+/-8.9%, H: 2.6+/-3.6%, P: 1.6+/-6.1%; p=ns). Rate of +/-dp/dt-changes tended to decrease in [H] (+dp/dt: C: 3.9+/-15.5%, H: -10.0+/-25.2%, P: 0.3+/-19.6%; p=ns, -dp/dt: C: -0.1+/-19.5%, H: -8.5+/-20.4%, P: 5.7+/-27.7%; p=ns).

CONCLUSION

In this study, PPI and high-dose H2-blocker have EF-reducing tendency. However, these changes were small and these drugs seemed to exhibit little influence clinically.

Post-infarct treatment with an erythropoietin-gelatin hydrogel drug delivery system for cardiac repair

AIMS

We investigated the effect of an erythropoietin (EPO)-gelatin hydrogel drug delivery system (DDS) applied to the heart on myocardial infarct (MI) size, left ventricular (LV) remodelling and function.

METHODS AND RESULTS

Experiments were performed in a rabbit model of MI. The infarct size was reduced, and LV remodelling and function were improved 14 days and 2 months after MI but not at 2 days after MI in the EPO-DDS group. The number of cluster of differentiation 31(CD31)-positive microvessels and the expression of erythropoietin receptor (EPO-R), phosphorylated-Akt (p-Akt), phosphorylated glycogen synthase kinase 3beta (p-GSK-3beta), phosphorylated extracellular signal-regulated protein kinase (p-ERK), phosphorylated signal transducer and activator of transcription 3 (p-Stat3), vascular endothelial growth factor (VEGF), and matrix metalloproteinase-1 (MMP-1) were significantly increased in the myocardium of the EPO-DDS group.

CONCLUSION

Post-MI treatment with an EPO-DDS improves LV remodelling and function by activating prosurvival signalling, antifibrosis, and angiogenesis without causing any side effect.

Development of integrated backscatter intravascular ultrasound for tissue characterization of coronary plaques

Tissue characterization of plaques of coronary arteries is important to clarify the process of acute coronary syndrome and prevent it. The purpose of this study is to develop an online integrated backscatter intravascular ultrasound (IB-IVUS) system and validate the diagnostic accuracy for the characterization of coronary plaques. A personal computer equipped with custom software was connected to an IVUS imaging system. Images were acquired from 242 segments of 46 coronary arteries from 25 cadavers obtained at autopsy. In the training study, a total of 724 regions-of-interests on color-coded maps were compared with histologic images. In the validation study, a total of 192 cross-sections of coronary arteries were evaluated. Receiver operating characteristic curve analysis showed that the cut-off points of -49 dB (area under curve = 0.98) and -29 dB (area under curve = 0.99) were the most reliable predictors of lipid pools, fibrosis and calcification. In the validation study, the analysis using IB values classified fibrous, lipid-rich and fibrocalcific plaque components with a high accuracy of 93%, 90% and 96%, respectively. The overall agreement between histologic and IB-IVUS diagnoses (n = 175) was high (Cohen's kappa = 0.81). The IB-IVUS system provides high diagnostic accuracy for analysis of tissue characteristics of coronary plaques.

Effect of a long-term treatment with a low-dose granulocyte colony-stimulating factor on post-infarction process in the heart

Although beneficial effects of granulocyte colony-stimulating factor (G-CSF) have been demonstrated on post-myocardia infarction (MI) process, the mechanisms and feasibility are not fully agreed yet. We investigated effects of a long-term treatment with a low-dose G-CSF started 1 day after the onset of MI, on post-infarction process. One day after being made MI by left coronary ligation, mice were given G-CSF (10 μg/kg/day) for 4 weeks. The G-CSF treatment resulted in a significant mitigation of cardiac remodelling and dysfunction. In the G-CSF-treated hearts, the infarcted scar was smaller with less fibrosis and abundant vessels while in the non-infarcted area, hypertrophic cardiomyocytes with attenuated degenerative changes and reduced fibrosis were apparent. These effects were accompanied by activation of signal transducer and activator of transcription 3 (STAT3) and Akt and also by up-regulation of GATA-4, myosin heavy chain and matrix metalloproteinases-2 and -9. Apoptosis of cardiomyocytes appeared insignificant at any stages. Parthenolide, a STAT3 inhibitor, completely abolished the beneficial effects of G-CSF on cardiac function and remodelling with loss of effect on both anti-cardiomyocyte degeneration and anti-fibrosis. In contrast, wortmannin, an Akt inhibitor, did not affect G-CSF-induced benefis despite cancelling vessel increase. In conclusion, treatment with G-CSF at a small dose but for a long duration beneficially affects the post-infarction process possibly through STAT3-mediated anti-cardiomyocyte degeneration and anti-fibrosis, but not through anti-cardiomyocyte apoptosis or Akt-mediated angio-genesis. The findings may also imply a more feasible way of G-CSF administration in the clinical settings.

Treatment with an adenoviral vector encoding hepatocyte growth factor mitigates established cardiac dysfunction in doxorubicin-induced cardiomyopathy

Hepatocyte growth factor (HGF) reportedly exerts beneficial effects on the heart following myocardial infarction and during nonischemic cardiomyopathy, but the precise mechanisms underlying the latter have not been well elucidated. We generated nonischemic cardiomyopathy in mice by injecting them with doxorubicin (15 mg/kg ip). Two weeks later, when cardiac dysfunction was apparent, an adenoviral vector encoding human HGF gene (Ad.CAG-HGF, 1x10(11) particles/mouse) was injected into the hindlimb muscles; LacZ gene served as the control. Left ventricular dilatation and dysfunction normally seen 4 wk after doxorubicin administration were significantly mitigated in HGF-treated mice, as were the associated cardiomyocyte atrophy/degeneration and myocardial fibrosis. Myocardial expression of GATA-4 and a sarcomeric protein, myosin heavy chain, was downregulated by doxorubicin, but the expression of both was restored by HGF treatment. The protective effect of HGF against doxorubicin-induced cardiomyocyte atrophy was confirmed in an in vitro experiment, which also showed that neither cardiomyocyte apoptosis nor proliferation plays significant roles in the present model. Upregulation of c-Met/HGF receptor was noted in HGF-treated hearts. Among the mediators downstream of c-Met, the activation of extracellular signal-regulated kinase (ERK) was reduced by doxorubicin, but the activity was restored by HGF. Levels of transforming growth factor-beta1 and cyclooxygenase-2 did not differ between the groups. Our findings suggest the HGF gene delivery exerts therapeutic antiatrophic/degenerative and antifibrotic effects on myocardium in cases of established cardiac dysfunction caused by doxorubicin. These beneficial effects appear to be related to HGF-induced ERK activation and upregulation of c-Met, GATA-4, and sarcomeric proteins.

Effects of benidipine and some other calcium channel blockers on the prognosis of patients with vasospastic angina. Cohort study with evaluation of the ergonovine coronary spasm induction test

BACKGROUND

It has been reported that the morbidity rate of vasospastic angina is higher in Japan compared to western countries, and its prognosis has already been reported. However, the prognosis of vasospastic angina in relation to coronary angiographic findings, prognostic risk factors and treatment has not yet been fully investigated.

METHODS AND RESULTS

From January 2000 to October 2005, 1047 patients with vasospastic angina diagnosed by coronary angiography at Gifu University Hospital and related hospitals were registered in a cohort study (follow-up rate: 91.4%, median follow-up duration: 3.8 years). The presence of coronary artery stenosis, diabetes mellitus, total spasm, and age of more than 65 years had a negative prognostic impact on cardiovascular events. Patients were treated with calcium channel blockers such as diltiazem (CAS 33286-22-5, CAS 42399-41-7), amlodipine (CAS 111470-99-6), nifedipine (CAS 21829-25-4), and benidipine (CAS 91599-74-5). Among these calcium channel blockers, when patient background was matched by the propensity score in patients treated with calcium channel blockers only, the cardiovascular event rate was significantly lower in the benidipine group than in the diltiazem group.

CONCLUSION

The study demonstrated for the first time that total spasm is a risk factor, independent of other factors, for cardiovascular events in patients with vasospastic angina. Treatment with benidipine showed a better prognosis than that with diltiazem.

Amlodipine inhibits granulation tissue cell apoptosis through reducing calcineurin activity to attenuate postinfarction cardiac remodeling

Although amlodipine, a long-acting L-type calcium channel blocker, reportedly prevents left ventricular remodeling and dysfunction after myocardial infarction, the mechanism responsible is not yet well understood. Myocardial infarction was induced in mice by ligating the left coronary artery. Treatment of mice with amlodipine (10 mg·kg−1·day−1), beginning on the third day postinfarction, significantly improved survival and attenuated left ventricular dilatation and dysfunction 4 wk postinfarction compared with treatment with saline or hydralazine. Although infarct sizes did not differ among the groups, the infarcted wall thickness was greater and the infarct segment length was smaller in the amlodipine-treated group, and cellular components, including vessels and myofibroblasts, were abundant within the infarcted area. Ten days postinfarction (the subacute stage), the proliferation of granulation tissue cells in the infarcted area was similar among the groups, but the incidence of apoptosis was significantly lower in the amlodipine-treated group, where Bad, a proapoptotic Bcl-2 family protein, was significantly phosphorylated (inactivated). Calcineurin, which dephosphorylates (activates) Bad, was upregulated in infarcted hearts, but its levels were significantly reduced by amlodipine treatment. In vitro, Fas stimulation augmented calcineurin activity and induced apoptosis among infarct tissue-derived myofibroblasts; both of those effects were strongly inhibited by amlodipine, two other calcium channel blockers (verapamil or nifedipine), and two calcineurin inhibitors (cyclosporin A or FK-506). Amlodipine inhibits Fas-mediated granulation tissue cell apoptosis in infarcted hearts, possibly by attenuating the activities of calcineurin and Bad. These findings may provide new insight into the mechanism by which calcium channel blockers attenuate postinfarction cardiac remodeling and dysfunction.

Narirutin inhibits airway inflammation in an allergic mouse model

1. Flavonoids are naturally occurring compounds that possess anti-allergic, anti-inflammatory, antiproliferative and anti-oxidant properties. In the present study, we investigated whether the flavonoid narirutin could reduce airway inflammation in ovalbumin (OVA)-sensitized/challenged NC/Nga mice, a model of allergic eosinophilic airway inflammation. 2. Mice were initially immunized intraperitoneally with OVA on Days 0 and 7 and then challenged with inhaled OVA on Days 14, 15 and 16. In addition, some mice received narirutin orally at doses of 0.1, 1 or 10 mg/kg bodyweight daily on Days 7-16. 3. At 10 mg/kg, but not 0.1 or 1 mg/kg, narirutin significantly diminished OVA-induced airway inflammation caused by infiltration of lung tissue with inflammatory and mucus-producing cells, as well as reduced eosinophil counts in the peripheral blood and bronchoalveolar lavage fluid (BALF), interleukin (IL)-4 levels in BALF and IgE levels in serum. 4. The mechanism of the anti-inflammatory effect of narirutin are likely to be associated with a reduction in the OVA-induced increases of IL-4 and IgE in a murine model of allergic eosinophilic airway inflammation. These findings suggest that narirutin may be an effective new tool in the treatment of bronchial asthma.