TGFBR2 mutations alter smooth muscle cell phenotype and predispose to thoracic aortic aneurysms and dissections.

AIMS: Transforming growth factor-ß (TGF-ß) signaling is critical for the differentiation of smooth muscle cells (SMCs) into quiescent cells expressing a full repertoire of contractile proteins. Heterozygous mutations in TGF-ß receptor type II (TGFBR2) disrupt TGF-ß signaling and lead to genetic conditions that predispose to thoracic aortic aneurysms and dissections (TAADs). The aim of this study is to determine the molecular mechanism by which TGFBR2 mutations cause TAADs. METHODS AND RESULTS: Using aortic SMCs explanted from patients with TGFBR2 mutations, we show decreased expression of SMC contractile proteins compared with controls. Exposure to TGF-ß1 fails to increase expression of contractile genes in mutant SMCs, whereas control cells further increase expression of these genes. Analysis of fixed and frozen aortas from patients with TGFBR2 mutations confirms decreased in vivo expression of contractile proteins relative to unaffected aortas. Fibroblasts explanted from patients with TGFBR2 mutations fail to transform into mature myofibroblasts with TGF-ß1 stimulation as assessed by expression of contractile proteins. CONCLUSIONS: These data support the conclusion that heterozygous TGFBR2 mutations lead to decreased expression of SMC contractile protein in both SMCs and myofibroblasts. The failure of TGFBR2-mutant SMCs to fully express SMC contractile proteins predicts defective contractile function in these cells and aligns with a hypothesis that defective SMC contractile function contributes to the pathogenesis of TAAD.

Pitavastatin reduces oxidative stress and attenuates intermittent hypoxia-induced left ventricular remodeling in lean mice.

We have reported previously that intermittent hypoxia related to sleep apnea induces cardiovascular remodeling secondary to the oxidative stress. The aim of this study was to examine the effect of pitavastatin as an antioxidant to prevent intermittent hypoxia-induced left ventricular (LV) remodeling in mice without hypercholesterolemia. Eight-week-old male C57BL/6J mice (n=35) were exposed to intermittent hypoxia (30 s exposure to 5% oxygen, followed by 30 s exposure to 21% oxygen) for 8 h per day during the daytime or maintained under normoxic conditions; in addition, they were either treated with pitavastatin (3 mg kg(-1) per day) or vehicle for 10 days. After cardiac catheterization and blood sampling, the LV myocardium was examined. The systemic blood pressure and plasma level of total cholesterol were similar among the four groups. Intermittent hypoxia significantly increased the expression levels of 4-hydroxy-2-nonenal (4-HNE) proteins, TNF-alpha and TGF-beta mRNA, and also the number of terminal deoxynucleotidyl transferase-mediated dUTP-biotin end labeling (TUNEL)-positive myocardial cells in the LV myocardium. In addition, enhanced hypertrophy of the cardiomyocytes, perivascular fibrosis and histological degeneration were observed in the mice exposed to hypoxic stress. Treatment with pitavastatin significantly suppressed the expression levels of the 4-HNE proteins, cytokines, superoxide production and TUNEL-positive myocardial cells in the LV myocardium, consequently attenuating the hypoxia-induced histological changes. Pitavastatin preserved, at least partially, the morphological structure of the LV myocardium in lean mice exposed to intermittent hypoxia, through its antioxidant effect.

Genetic basis of thoracic aortic aneurysms and dissections: focus on smooth muscle cell contractile dysfunction.

Thoracic aortic aneurysms leading to type A dissections (TAAD) can be inherited in isolation or in association with genetic syndromes, such as Marfan syndrome and Loeys-Dietz syndrome. When TAAD occurs in the absence of syndromic features, it is inherited in an autosomal dominant manner with decreased penetrance and variable expression, the disease is referred to as familial TAAD. Familial TAAD exhibits significant clinical and genetic heterogeneity. The first genes identified to cause TAAD were FBN1, TGFBR2, and TGFBR1. The identification and characterization of these genes suggested that increased TGF-beta signaling plays a role in pathogenesis. The recent discovery that mutations in the vascular smooth muscle cell (SMC)-specific beta-myosin (MYH11) and alpha-actin (ACTA2) can also cause this disorder has focused attention on the importance of the maintenance of SMC contractile function in preserving aortic structure and preventing TAAD.

Humanized anti-CD26 monoclonal antibody as a treatment for malignant mesothelioma tumors.

PURPOSE: CD26 is a 110-kDa cell surface antigen with a role in tumor development. In this report, we show that CD26 is highly expressed on the cell surface of malignant mesothelioma and that a newly developed humanized anti-CD26 monoclonal antibody (mAb) has an inhibitory effect on malignant mesothelioma cells in both in vitro and in vivo experiments. EXPERIMENTAL DESIGN: Using immunohistochemistry, 12 patients' surgical specimens consisting of seven malignant mesothelioma, three reactive mesothelial cells, and two adenomatoid tumors were evaluated for expression of CD26. The effects of CD26 on malignant mesothelioma cells were assessed in the presence of transfection of CD26-expressing plasmid, humanized anti-CD26 mAb, or small interfering RNA against CD26. The in vivo growth inhibitory effect of humanized anti-CD26 mAb was assessed in human malignant mesothelioma cell mouse xenograft models. RESULTS: In surgical specimens, CD26 is highly expressed in malignant mesothelioma but not in benign mesothelial tissues. Depletion of CD26 by small interfering RNA results in the loss of adhesive property, suggesting that CD26 is a binding protein to the extracellular matrix. Moreover, our in vitro data indicate that humanized anti-CD26 mAb induces cell lysis of malignant mesothelioma cells via antibody-dependent cell-mediated cytotoxicity in addition to its direct anti-tumor effect via p27(kip1) accumulation. In vivo experiments with mouse xenograft models involving human malignant mesothelioma cells show that humanized anti-CD26 mAb treatment drastically inhibits tumor growth in tumor-bearing mice, resulting in enhanced survival. CONCLUSIONS: Our data strongly suggest that humanized anti-CD26 mAb treatment may have potential clinical use as a novel cancer therapeutic agent in CD26-positive malignant mesothelioma.

Anti-CD26 monoclonal antibody-mediated G1-S arrest of human renal clear cell carcinoma Caki-2 is associated with retinoblastoma substrate dephosphorylation, cyclin-dependent kinase 2 reduction, p27(kip1) enhancement, and disruption of binding to the extracellular matrix.

PURPOSE: CD26 is a 110-kDa cell surface glycoprotein with a role in tumor development through its association with key intracellular proteins. In this report, we show that binding of soluble anti-CD26 monoclonal antibody (mAb) inhibits the growth of the human renal carcinoma cells in both in vitro and in vivo experiments. EXPERIMENTAL DESIGN: Growth inhibition by anti-CD26 mAb was assessed using proliferation assay and cell cycle analysis. Anti-CD26 mAb, chemical inhibitors, dominant-negative, or constitutively active forms of specific signaling molecules were used to evaluate CD26-associated pathways. The in vivo growth-inhibitory effect of anti-CD26 mAb was also assessed in a human renal carcinoma mouse xenograft model. RESULTS: In vitro experiments show that anti-CD26 mAb induces G1-S cell cycle arrest associated with enhanced p27(kip1) expression, down-regulation of cyclin-dependent kinase 2, and dephosphorylation of retinoblastoma substrate. Moreover, our data show that enhanced p27(kip1) expression is dependent on the attenuation of Akt activity. Anti-CD26 mAb also internalizes cell surface CD26, leading to decreased binding to collagen and fibronectin. Experiments with a mouse xenograft model involving human renal carcinoma cells show that anti-CD26 mAb treatment drastically inhibits tumor growth in tumor-bearing mice, resulting in enhanced survival. CONCLUSIONS: Taken together, our data strongly suggest that anti-CD26 mAb treatment may have potential clinical use for CD26-positive renal cell carcinomas.

Angiotensin-II receptor blocker exerts cardioprotection in diabetic rats exposed to hypoxia.

BACKGROUND: Hypoxia caused by sleep apnea might be associated with an increased risk of cardiovascular events in subjects with metabolic syndrome. The aim of this study was to examine the effect of hypoxia on the left ventricular (LV) myocardium and evaluate the cardioprotective effect of an angiotensin-II receptor blocker (ARB) in diabetic rats. METHODS AND RESULTS: Male Otsuka Long-Evans Tokushima Fatty (OLETF) rats at 30 weeks of age (n=30) were divided into 2 groups that were treated with vehicle or candesartan 0.2 mg x kg(-1) x day (-1). The animals were housed in a hypoxic gas chamber (oxygen, 10.0+/-0.5%, mean +/- standard deviation) for 2 weeks. Hypoxia increased right ventricular (RV) systolic pressure (hypoxia; 78+/-14 mmHg vs control; 22+/-5, p<0.05), but did not increase LV systolic pressure (131+/-23 mmHg vs 121+/-10). Hypoxia exacerbated the degeneration of cardiomyocytes, and accelerated the expression of hypoxia inducible factor-1alpha (HIF-1 alpha) and vascular endothelial growth factor (VEGF) in the myocardium. Treatment with ARB decreased RV and LV pressures (46+/-7 and 100+/-18 mmHg, respectively), suppressed the expression of HIF-1alpha and VEGF, and preserved the fine structure of the LV myocardium. CONCLUSIONS: ARB exhibited cardioprotection under hypoxia, in part through the reduction of blood pressure and cytokine expression, in OLETF rats. Thus, ARB might be a potent agent for the treatment of diabetic patients with the complication of sleep apnea.

Nifedipine enhances the cardioprotective effect of an angiotensin-II receptor blocker in an experimental animal model of heart failure.

This study was designed to examine the hypothesis that a calcium channel blocker nifedipine (CCB) could enhance the cardioprotective effect of an angiotensin-ll receptor blocker candesartan (ARB) in the treatment for heart failure. Isoproterenol (ISP) was injected into male rats at 300 mg/kg to produce progressive heart failure. Three months later, the rats were divided into 4 groups and treated for 4 weeks with 1) vehicle (n = 20), 2) ARB at 0.2 mg/kg/day (n = 6), 3) CCB at 10 mg/kg/day (n = 6), or 4) both drugs (n = 8). Rats injected with saline served as controls (n = 13). ISP caused severe myocardial degeneration and decreased the capillary density (D(cap)) of the left ventricular (LV) myocardium (mean +/- SD: 2,197 +/- 627 vs. 2,847 +/- 298 N/mm2 for normal controls), while increasing plasma thiobarbituric acid-reactive substances (TBARS; 3.6 +/- 1.1 vs. 1.9 +/- 0.5 nmol/ml). Although ARB therapy preserved cardiac morphology, it had little effect on D(cap) or oxidative stress. On the other hand, CCB decreased plasma TBARS and 4-hydroxy-2-nonenal protein expression in LV myocardium. Furthermore, the combination of CCB and ARB increased D(cap) and preserved the ultrastructure of LV myocardium, so this combination may be a useful option for the treatment of heart failure.

Vascular endothelial growth factor-expressing mesenchymal stem cell transplantation for the treatment of acute myocardial infarction.

OBJECTIVE: Vascular endothelial growth factor (VEGF) plays an important role in inducing angiogenesis. Mesenchymal stem cells (MSCs) may have potential for differentiation to several types of cells, including myocytes. We hypothesized that transplantation of VEGF-expressing MSCs could effectively treat acute myocardial infarction (MI) by providing enhanced cardioprotection, followed by angiogenic effects in salvaging ischemic myocardium. METHODS AND RESULTS: The human VEGF165 gene was transfected to cultured MSCs of Lewis rats using an adenoviral vector. Six million VEGF-transfected and LacZ-transfected MSCs (VEGF group), LacZ-transfected MSCs (control group), or serum-free medium only (medium group) were injected into syngeneic rat hearts 1 hour after left coronary artery occlusion. At 1 week after MI, MSCs were detected by X-gal staining in infarcted region. High expression of VEGF was immunostained in the VEGF group. At 28 days after MI, infarct size, left ventricular dimensions, ejection fraction, E wave/A wave ratio and capillary density of the infarcted region were most improved in the VEGF group, compared with the medium group. Immunohistochemically, alpha-smooth muscle actin-positive cells were most increased in the VEGF group. CONCLUSIONS: This combined strategy of cell transplantation with gene therapy could be a useful therapy for the treatment of acute MI.

Chronic hypoxia accelerates the progression of atherosclerosis in apolipoprotein E-knockout mice.

The aim of this study was to investigate the effect of chronic hypoxia on the development and progression of atherosclerosis in apolipoprotein E-knockout (apoE-KO) mice. Male and female apoE-KO mice (6 weeks old) and age- and sex-matched wild-type mice were kept under hypoxic conditions (10.0 +/- 0.5% O2) in a gas chamber or in room air for 3 weeks. Aortic atherosclerotic plaque was not observed in wild-type mice under normoxic or hypoxic conditions. In the apoE-KO mice, however, hypoxia induced proliferation of smooth muscle cells and plaque formation in the aorta, which were not observed under normoxic conditions. Although sexual dimorphism of the response to hypoxia was not observed, these hypoxia-induced atherogenic changes were accompanied by a significant increase of plasma low density lipoprotein (LDL) cholesterol and NADPH-dependent vascular superoxide (O2-) production. Furthermore, matrix metalloproteinase (MMP)-9 was activated in the aorta of apoE-KO mice. In conclusion, chronic hypoxia accelerated the development of atherosclerosis in apoE-KO mice, along with increased O2- production and activated MMP-9 in the aorta.

Core protein of hepatitis C virus induces cardiomyopathy.

Hepatitis C virus (HCV) has been reported to be associated with cardiomyopathy. However, the mechanism of cardiomyopathy in chronic HCV infection is still unclear. Therefore, we investigate the development of cardiomyopathy in mice transgenic for the HCV-core gene. After the age of 12 months, mice developed cardiomyopathy that appeared as left ventricular dilatation, and systolic and diastolic dysfunction assessed by Doppler echocardiography. Histologically, hypertrophy of cardiomyocytes, cardiac fibrosis, disarray and scarcity of myofibrils, vacuolization and deformity of nuclei, myofibrillar lysis, streaming of Z-bands, and an increased number of bizarre-shaped mitochondria were found in HCV-core transgenic mice. These histological changes are just consistent with cardiomyopathy. In conclusion, the HCV-core protein directly plays an important role in the development of cardiomyopathy.

Efficacy of edaravone, a free radical scavenger, on left ventricular function and structure in diabetes mellitus.

This study was designed to assess the efficacy of edaravone (3-methyl-1-phenyl-2-pyrazolin-5-one), a free radical scavenger that possesses anti-oxidant effects, on cardiac function and fine structure of the left ventricular myocardium in diabetes mellitus. Male Otsuka Long-Evans Tokushima Fatty (OLETF) rats, a model of spontaneous development of type II diabetes (30 weeks; n = 15) were divided into two groups and treated with edaravone 30 mg/kg/d or vehicle for 2 weeks. OLETF rats showed hyperglycemia (352 +/- 71 mg/dl vs normal control; 128 +/- 52 mg/dl), increased thiobarbituric acid-reactive substances (TBARS; 6.9 +/- 2.5 nM/ml vs 2.8 +/- 0.6 nM/ml), and decreased superoxide dismutase activity (21.5 +/- 0.9 U/ml vs 25.8 +/- 0.7 U/ml). Increased left ventricular end-diastolic pressure (12 +/- 3 mm Hg vs 6 +/- 2 mm Hg) and hypertrophied cardiocytes (23.1 +/- 1.4 vs 17.6 +/- 1.0 microm) were also observed (P < 0.05, respectively). Edaravone could not improve plasma glucose level and hemodynamic parameters but significantly decreased TBARS values (3.8 +/- 0.5) and increased superoxide dismutase activity (24.5 +/- 0.8) (vs OLETF, P < 0.05, respectively). Moreover, edaravone effectively preserved cardiocyte diameter (18.2 +/- 0.9 microm) and the fine structure of mitochondria. Thus, edaravone exhibits modest cardiac protection in diabetes mellitus independent of blood sugar level.