Arteriogenic therapy by intramyocardial sustained delivery of a novel growth factor combination prevents chronic heart failure.

BACKGROUND: Therapeutic angiogenesis is a promising approach for the treatment of cardiovascular diseases, including myocardial infarction and chronic heart failure. We aimed to improve proangiogenic therapies by identifying novel arteriogenic growth factor combinations, developing injectable delivery systems for spatiotemporally controlled growth factor release, and evaluating functional consequences of targeted intramyocardial growth factor delivery in chronic heart failure. METHODS AND RESULTS: First, we observed that fibroblast growth factor and hepatocyte growth factor synergistically stimulate vascular cell migration and proliferation in vitro. Using 2 in vivo angiogenesis assays (n=5 mice per group), we found that the growth factor combination results in a more potent and durable angiogenic response than either growth factor used alone. Furthermore, we determined that the molecular mechanisms involve potentiation of Akt and mitogen-activated protein kinase signal transduction pathways, as well as upregulation of angiogenic growth factor receptors. Next, we developed crosslinked albumin-alginate microcapsules that sequentially release fibroblast growth factor-2 and hepatocyte growth factor. Finally, in a rat model of chronic heart failure induced by coronary ligation (n=14 to 15 rats per group), we found that intramyocardial slow release of fibroblast growth factor-2 with hepatocyte growth factor potently stimulates angiogenesis and arteriogenesis and prevents cardiac hypertrophy and fibrosis, as determined by immunohistochemistry, leading to improved cardiac perfusion after 3 months, as shown by magnetic resonance imaging. These multiple beneficial effects resulted in reduced adverse cardiac remodeling and improved left ventricular function, as revealed by echocardiography. CONCLUSION: Our data showing the selective advantage of using fibroblast growth factor-2 together with hepatocyte growth factor suggest that this growth factor combination may constitute an efficient novel treatment for chronic heart failure.

Coronary endothelial dysfunction after cardiomyocyte-specific mineralocorticoid receptor overexpression.

The deleterious effects of aldosterone excess demonstrated in cardiovascular diseases might be linked in part to coronary vascular dysfunction. However, whether such vascular dysfunction is a cause or a consequence of the changes occurring in the cardiomyocytes is unclear. Moreover, the possible link between mineralocorticoid receptor (MR)-mediated effects on the cardiomyocyte and the coronary arteries is unknown. Thus we used a mouse model with conditional, cardiomyocyte-specific overexpression of human MR (hMR) and observed the effects on endothelial function in isolated coronary segments. hMR overexpression decreased the nitric oxide (NO)-mediated relaxing responses to acetylcholine in coronary arteries (but not in peripheral arteries), and this was prevented by a 1-mo treatment either with an MR antagonist, vitamin E/vitamin C, or a NADPH oxidase inhibitor. hMR overexpression did not affect coronary endothelial NO synthase content nor its level of phosphorylation on serine 1177, but increased cardiac levels of reactive oxygen species, cardiac NADPH oxidase (NOX) activity, and expression of the NOX subunit gp91phox, which was limited to endothelial cells. Thus an increase in hMR activation, restricted to cardiomyocytes, is sufficient to induce a severe coronary endothelial dysfunction. We suggest a new paracrine mechanism by which cardiomyocytes trigger a NOX-dependent, reactive oxygen species-mediated coronary endothelial dysfunction.

Improvement of peripheral endothelial dysfunction by protein tyrosine phosphatase inhibitors in heart failure.

BACKGROUND: Chronic heart failure (CHF) induces endothelial dysfunction characterized by a decrease in nitric oxide (NO) production in response to flow (flow-mediated dilatation [FMD]). Because activation of endothelial NO synthase (eNOS) by flow requires tyrosine phosphorylation, we tested whether endothelial dysfunction could be corrected by increasing phosphotyrosine levels using protein tyrosine phosphatase (PTP) inhibitors and especially inhibitors of PTP1B. METHODS AND RESULTS: CHF was induced by coronary ligation in mice, and FMD was assessed in isolated and cannulated mesenteric artery segments (2 mm in length and <300 microm in diameter). CHF almost abolished FMD but only moderately affected the response to acetylcholine. In mice with CHF, the PTP1B inhibitors AS279, AS098, and AS713 restored FMD to levels similar to those of normal mice. This restoration was reduced by inhibitors of eNOS and phosphatidylinositol-3 kinase. Polymerase chain reaction and Western blot showed that arteries express PTP1B, and this expression was not affected by CHF. Immunolocalization revealed the presence of PTP1B in the endothelium and the adventitia. Flow induced a transient eNOS phosphorylation that was absent in CHF. PTP1B inhibition stimulated early eNOS phosphorylation and increased phosphorylation of Akt. CONCLUSIONS: Our results demonstrate for the first time that PTP1B inhibitors may be potent treatments for endothelial dysfunction.

Role of alpha1-adrenoreceptors in cocaine-induced NADPH oxidase expression and cardiac dysfunction.

OBJECTIVE: We assessed whether alpha1-adrenoreceptor (alpha1-AR) stimulation contributes to activation of myocardial NADPH oxidase in a rat model of cocaine-induced cardiac dysfunction. METHODS AND RESULTS: After 7 days of cocaine injection (2 x 7.5 mg/kg/day, i.p., Coc), NADPH activity assessed by chemiluminescence increases as well as phosphorylation of p47phox, one of the cytosolic components of NADPH oxidase. The alpha1-AR antagonist prazosin (Prz), administered 1 h before each cocaine injection (2 x 1 mg/kg/day, i.p., Coc+Prz), prevents these effects. Moreover, Prz pretreatment reduces left ventricular/body weight (LV/BW) ratio and partially prevents the cocaine-induced alterations in fractional shortening and cardiac index assessed by echocardiography. In order to confirm the involvement of alpha1-AR stimulation in NADPH oxidase up-regulation in vivo, we used phenylephrine (Phe) administration with the same protocol of injections as that used with cocaine (2 x 5 microg/kg/day, i.p.). After Phe administration, as expected, NADPH oxidase activity increases as well as phosphorylation of p47phox. These effects occur in the absence of sustained hemodynamic changes. CONCLUSION: This study demonstrates the involvement of the alpha1-AR in NADPH oxidase activation and in cocaine-induced LV dysfunction. We suggest that alpha1-AR stimulation, at least in part via NADPH oxidase induction, plays a critical role in the events leading to the cardiomyopathy observed after cocaine abuse.

A kinetic study of SDF-1, VEGF and MCP-1 blood and tissue levels after aortic transplantation in mice.

Vascular rejection is characterized by intimal proliferation and perivascular inflammation. We hypothesize that recipient stem cell therapy could prevent or ameliorate the development of the obliterative lesion. We studied the kinetic expression of three cytokines (SDF-1, MCP-1, VEGF) implicated in mobilization, homing and differentiation of progenitor cells during vascular aggression. An aortic allograft mouse model was used (BALBc donor-C57BL6/j recipient). Ten mice were sacrificed at Day 0, D1, D3, D6, D9, D12, and D20. Cytokine rates were measured in blood and in graft tissue by an ELISA technique. Results showed that in the allograft, SDF-1 and VEGF tissue levels were significantly increased at D12 as compared to the isograft (SDF-1: 22.16 ng/mg vs. 5.69 ng/mg, t=3.38; VEGF: 28.3 pg/mg vs. 9.3 pg/mg, t=3.06). In allografted and isografted groups, MCP-1 tissue levels were higher at D0 as compared to the other time points, without any difference between the two groups. These results prompt us to consider cell therapy at D0 and D12 in this mouse model of aortic graft.

Soluble epoxide hydrolase inhibition prevents coronary endothelial dysfunction in mice with renovascular hypertension.

OBJECTIVES: The study addresses the hypothesis that endothelial dysfunction in experimental arterial hypertension can be related to an alteration in epoxyeicosatrienoic acids (EETs) pathway and can be prevented by the inhibition of EETs degradation by soluble epoxide hydrolase (sEH). METHODS AND RESULTS: Arterial hypertension was induced in FVB/N mice by renal artery stenosis ('two-kidney-one-clip', 2K1C). Seven weeks after surgery, increased aortic pressures (Millar tonometer; Millar Instruments, Houston, Texas, USA) and cardiac hypertrophy (echocardiography) were present in 2K1C mice as compared with control mice. Left coronary artery endothelium-dependent relaxations to acetylcholine were decreased in 2K1C mice without modification in the relaxing responses to NS309 and NS1619, the openers of calcium-activated potassium channels mediating the hyperpolarizing effect of EETs. The inhibitors of the EET-synthesizing enzymes cytochrome P450 epoxygenases, fluconazole and N-methylsulfonyl-6-(2-propargyloxyphenyl)-hexanamide (MSPPOH), reduced the coronary relaxations to acetylcholine in control but not in 2K1C mice. The sEH expression was increased in 2K1C mice. The sEH inhibitor 12-(3-adamantan-1-yl-ureido)dodecanoic acid administered for 2 weeks starting 5 weeks after surgery in 2K1C mice (25 mg/l in drinking water) reduced aortic pressures and cardiac hypertrophy, improved the coronary relaxations to acetylcholine and restored the inhibitory effect of fluconazole and MSPPOH on acetylcholine-induced relaxations, without modifying the relaxations to NS309 and NS1619. CONCLUSION: These results demonstrate that a reduced EET-mediated relaxations related to an increased degradation by sEH contributes to coronary endothelial dysfunction in 2K1C hypertensive mice. Inhibiting sEH prevents endothelial dysfunction by restoring EET-mediated relaxations and thus, could represent a promising pharmacological intervention to limit cardiovascular morbidity and mortality in arterial hypertension.

Protective effect of mycophenolate mofetil on endothelial function in an aortic allograft model.

BACKGROUND: Whether mycophenolate mofetil (MMF) can prevent the vascular endothelial dysfunction related to the administration of calcineurin inhibitor after organ transplantation remains unknown. METHODS: Four groups of Lewis rats, grafted with Brown Norway donor aortic abdominal allograft, received since the transplantation cyclosporine A (CsA, 5 mg/kg/day), MMF (40 mg/kg/day), CsA+MMF, or vehicle (control) for 2 weeks. RESULTS: Fifteen days after transplantation, all immunosuppressive regimens were equally effective in preventing graft rejection. When compared with control rats, the endothelium-dependent relaxation to acetylcholine was reduced, and the vasoconstrictor effect of phenylephrine was enhanced in thoracic aorta of CsA-treated rats but not in rats treated with MMF alone or combined with CsA without difference for the endothelium-independent relaxation to sodium nitroprusside. The relaxation to acetylcholine was abolished by the nitric oxide (NO)-synthase inhibitor N-nitro-l-arginine in all groups. Moreover, the endothelial NO-synthase protein dimer:monomer ratio in the thoracic aorta and the plasma nitrites concentrations, an indicator of NO availability, were decreased in CsA-treated rats but not in rats treated with MMF alone or combined with CsA. CONCLUSIONS: This study demonstrates that MMF prevents systemic endothelial dysfunction and the enhanced sensitivity to vasoconstrictors related to CsA administration in a rat allograft aortic model through an increase in NO availability related to the improvement of endothelial NO-synthase functionality.

NADPH oxidase inhibition prevents cocaine-induced up-regulation of xanthine oxidoreductase and cardiac dysfunction.

Oxidative stress is involved in the pathogenesis of cocaine-induced cardiomyopathy. In the present study, we aimed to determine the enzymatic sources of reactive oxygen species (ROS) production, namely NADPH oxidase and xanthine oxidoreductase (XOR) in male Wistar rats treated for 7 days with cocaine (2x7.5 mg/kg/day, ip) or cocaine with a NADPH oxidase inhibitor (apocynin, 50 mg/kg/day, po) or a XOR inhibitor (allopurinol, 50 mg/kg/day, po). Cocaine-induced cardiac dysfunction is associated with an increase in NADPH oxidase and XOR activities (59% and 29%, respectively) and a decrease in catalase activity. Apocynin or allopurinol treatment prevents the cocaine-induced cardiac alteration by restoration of cardiac output, stroke volume and fractional shortening. This is associated with a reduction of the myocardial production of superoxide anions and an enhancement of catalase activity. Surprisingly, apocynin treatment prevents XOR up-regulation supporting the hypothesis that NADPH oxidase-derived ROS play a role in modulating ROS production by XOR. These data suggest that NADPH and xanthine oxidase act synergically to form myocardial ROS and clearly demonstrate that their inhibition may be critical in preventing the initiation and progression of cocaine-induced LV dysfunction.

Transient reduction in myocardial free oxygen radical levels is involved in the improved cardiac function and structure after long-term allopurinol treatment initiated in established chronic heart failure.

AIMS: Oxidative stress, i.e. imbalance between reactive oxygen species (ROS) and antioxidant defences, contributes to the progression of chronic heart failure (CHF). Acute inhibition of xanthine oxidase (XO), which produces ROS, improves mechanical efficiency of the failing heart, but whether long-term XO inhibition exerts beneficial effects in CHF is unknown. METHODS AND RESULTS: In rats with established CHF induced by left coronary ligation, we assessed the effects of a 5-day and a 10-week treatment with the XO inhibitor allopurinol (50 mg kg(-1) day(-1)) on haemodynamics and left ventricular (LV) function and structure. Both acute and chronic allopurinol treatment increase cardiac output without modification of arterial pressure, but only chronic allopurinol treatment reduces LV end-diastolic pressure and LV relaxation constant. Chronic allopurinol treatment decreases both LV systolic and diastolic diameters, but acute allopurinol treatment only decreases LV systolic diameter. Moreover, chronic allopurinol decreases LV weight and collagen density. Despite XO inhibition after acute and chronic allopurinol treatment, as both treatments reduce uric acid plasma levels, only acute allopurinol treatment reduces LV ROS determined using electron spin resonance spectroscopy. However, the CHF-enhanced myocardial thiobarbituric acid reactive substances levels were never modified. CONCLUSION: In experimental CHF, long-term allopurinol treatment, initiated in a pathological state of overt CHF, improves LV haemodynamics and function and prevents LV remodelling. These long-term effects are, at least partially, caused by a transient reduction of myocardial ROS shortly after initiation of allopurinol treatment, but whether other mechanism(s), independent of myocardial redox 'status', such as reduced inflammation, are implicated remains to be confirmed.

Aberrant methylation of the CDKN2a/p16INK4a gene promoter region in preinvasive bronchial lesions: a prospective study in high-risk patients without invasive cancer.

Among the identified factors involved in malignant transformation, abnormal methylation of the CDKN2A/p16(INK4a) gene promoter has been described as an early event, particularly in bronchial cell cancerization. Precancerous bronchial lesions (n = 70) prospectively sampled during fluorescence endoscopy in a series of 37 patients at high risk for lung cancer were studied with respect to the methylation status of the CDKN2A gene. Methylation-specific polymerase chain reaction was performed on DNA extracted from pure bronchial cell populations derived from biopsies and detection of p16 protein was studied by immunohistochemistry on contiguous parallel biopsies. Aberrant methylation of the CDKN2A gene promoter was found in 19% of preinvasive lesions and its frequency increased with the histologic grade of the lesions. Methylation in at least 1 bronchial site was significantly more frequent in patients with cancer history, although there was no difference in the outcome of patients with or without methylation in bronchial epithelium. The other risk factors studied (tobacco and asbestos exposure) did not influence the methylation status. There was no relationship between CDKN2A methylation and the evolutionary character of the lesions. Our results confirm that abnormal methylation of the CDKN2A gene promoter is an early event in bronchial cell cancerization, which can persist for several years after carcinogen exposure cessation, and show that this epigenetic alteration cannot predict the evolution of precancerous lesions within a 2-year follow-up.