M. Chiariello

Membrane-Bound Protein Kinase A Inhibits Smooth Muscle Cell Proliferation In Vitro and In Vivo by Amplifying cAMP–Protein Kinase A Signals

Abstract— cAMP-dependent protein kinase is anchored to discrete cellular compartments by a family of proteins, the A-kinase anchor proteins (AKAPs). We have investigated in vivo and in vitro the biological effects of the expression of a prototypic member of the family, AKAP75, on smooth muscle cells. In vitro expression of AKAP75 in smooth muscle cells stimulated cAMP-induced transcription, increased the levels of the cyclin-dependent kinase-2 inhibitor p27kip1, and reduced cell proliferation. In vivo expression of exogenous AKAP75 in common carotid arteries, subjected to balloon injury, significantly increased the levels of p27kip1 and inhibited neointimal hyperplasia. Both the effects in smooth muscle cells in vitro and in carotid arteries in vivo were specifically dependent on the amplification of cAMP-dependent protein kinase (PKA) signals by membrane-bound PKA, as indicated by selective loss of the AKAP75 biological effects in mutants defective in the PKA anchor domain or by suppression of AKAP effects by the PKA-specific protein kinase inhibitor. These data indicate that AKAP proteins selectively amplify cAMP-PKA signaling in vitro and in vivo and suggest a possible target for the inhibition of the neointimal hyperplasia after vascular injury.

Effect of drug-eluting stents in patients with acute ST-segment elevation myocardial infarction undergoing percutaneous coronary intervention: a meta-analysis of randomised trials and an adjusted indirect comparison

AIMSnThe role of drug-eluting stent (DES) remains an unsettled issue in patients with ST-segment elevation myocardial infarction (STEMI). Therefore, we performed a meta-analysis of randomised trials to evaluate the clinical outcome of DES as compared with bare-metal stent (BMS) after percutaneous coronary intervention (PCI).nnnMETHODS AND RESULTSnWe undertook a literature search until July 2009. Thirteen clinical trials met inclusion criteria, with 7,244 patients enrolled. Up to 1-year, patients treated with DES as compared with BMS experienced less target-vessel revascularisation (TVR) (5.11% versus 11.19% respectively, p<0.00001) and recurrent myocardial infarction rates (3.03% versus 3.70% respectively, p=0.02). In addition, no significant differences were found in terms of cardiac death (2.80% versus 3.52%, p=0.21) and stent thrombosis (2.65% versus 2.76%, p=0.37). Using the adjusted indirect comparison, a significant difference between sirolimus- and paclitaxel-eluting stent was found when TVR was evaluated (OR [95% CI] =0.59 [0.40-0.89], p=0.01), without differences in other clinical outcomes.nnnCONCLUSIONSnIn patients undergoing PCI for STEMI, treatment with DES is associated with decreased TVR and myocardial infarction rates, without increasing cardiac death or stent thrombosis occurrence. Sirolimus-eluting stent is associated with a greater TVR reduction as compared to paclitaxel-eluting stent.

In vivo gene transfer: prevention of neointima formation by inhibition of mitogen-activated protein kinase kinase

BackgroundThe mitogenactivated protein kinase kinase (MAPKK) is a protein downstream ras which is rapidly activated in cells stimulated with various extracellular signals. These proteins are believed to play a pivotal role in integrating and transmitting transmembrane signals required for cell growth.Methods and ResultsTo study the effect of inhibition of MAPKK on smooth muscle cell (SMC) proliferationin vivo after vascular injury, we performed experimental balloon angioplasty using the standard Clowes technique in male Wistar rats 14-weeks old. The animals did not receive any treatment after vascular injury (N=6) or were randomly assigned to receive, after balloon injury, a 30% (w/v) pluronic gel solution applied to the injured carotid artery, containing respectively: 1) no plasmid DNA (n=10); 2) RSV-lacZ (encoding the β-galactosidase gene) as control gene without effects on SMC proliferation (n=10); 3) Tg-CAT (encoding cloramphenicol acetyl-transferase gene under the control of thyreoglobulin promoter) as an additional control gene without effects on SMC proliferation (n=7); 4) a negative mutant of Mitogen-Activated Protein Kinase Kinase (MAPKK) (n=13). Fourteen days after vascular injury, carotid arteries were removed and cross sections were cut and stained with hematoxylin/eosin. Morphometric analysis demonstrated, in the MAPKK-treated rats, a significant reduction of both neointima (0.096±0.018 mm2 vs. 0.184±0.019 mm2, p<0.01) and neointima/media ratio (0.603±0.103 vs. 1.147±0.161, p<0.01) compared to control DNA.ConclusionsThe inhibition of MAPKK, by a dominant inhibitor mutant gene, prevents the SMC proliferation after vascular injuryin vivo.

Is direct stenting superior to stenting with predilation in patients treated with percutaneous coronary intervention? results from a meta-analysis of 24 randomised controlled trials

Background In the last decade, direct stenting has been proposed as an alternative strategy to conventional stenting with balloon predilation. The aim of this study was to perform a meta-analysis of randomised trials comparing a direct stenting strategy versus a conventional one. Methods A literature search was performed using Medline, EMBASE, the Cochrane Central Register of Controlled Trials, scientific session abstracts and relevant websites, from inception of each database to June 2009. Included studies comprised randomised controlled trials evaluating direct versus conventional stenting in patients undergoing percutaneous coronary intervention. Primary endpoint was the composite of death or myocardial infarction and secondary endpoints were myocardial infarction and target-vessel revascularisation occurrence. Results 24 trials met inclusion criteria, with 6803 patients enrolled (3412 or 50.15% randomised to direct stenting and 3391 or 49.85% randomised to conventional stenting). Up to 6-month follow-up, the composite of death or myocardial infarction was significantly reduced with direct stenting compared with conventional stenting (3.95% versus 5.10% respectively, OR=0.76 (95% CI 0.60 to 0.96), p=0.02). This reduction was primarily driven by a lower myocardial infarction occurrence (3.16% versus 4.04%, respectively, OR=0.77 (0.59 to 0.99), p=0.04). Furthermore, direct stenting was not associated with a reduction in target-vessel revascularisation (6.50% versus 6.96%, respectively, OR=0.92 (0.76 to 1.12), p=0.42). Conclusion This meta-analysis demonstrates that, in selected coronary lesions, direct stenting improves outcome in patients undergoing percutaneous coronary intervention, primarily reducing myocardial infarction incidence.

Molecular effects of HMG-CoA reductase inhibitors on smooth muscle cell proliferation: Reply

Skaletz-Rorowski raises the issue that HMG-CoA reductase inhibitors have several targets in smooth muscle cell (SMC) proliferation that have not been completely identified yet. We agree with Skaletz-Rorowski and associates that further studies should be performed in order to understand the molecular

[Heart function in chronic pressure overload caused by aortic stenosis: the role of collagen tissue].

The purpose of this study was to evaluate left ventricular (LV) structure-function interplay in aortic stenosis. LV structure was assessed from endomyocardial biopsies obtained in 27 patients with aortic stenosis. Total collagen volume fraction, orthogonal collagen fiber meshwork (cross-hatching) and endocardial fibrosis were determined by morphologic-morphometric evaluation. Control biopsy data were obtained from 6 pre-transplantation donor hearts whereas other 11 patients with normal cardiac function served as hemodynamic controls. LV biplane cineangiography and high-fidelity LV pressure measurement were carried out in all patients. Systolic function was assessed by LV biplane ejection fraction, diastolic function by time constant of relaxation, peak filling rates and passive elastic properties. Total collagen volume fraction (7.3 versus 1.6%, p < 0.01) as well as the degree of cross-hatching (1.7 versus 0.8 grade, p < 0.01) were significantly increased in patients with aortic stenosis with respect to controls. Endocardial fibrosis was present in 11/27 patients with aortic stenosis and in no patients of control group. In aortic stenosis in presence of increased total collagen volume fraction there were no changes in systolic and diastolic function, whereas in presence of changes in collagen architecture ejection fraction was depressed and passive elastic properties increased. In conclusion, in aortic stenosis, changes in collagen architecture are associated with altered systolic function and passive diastolic properties. The sole increase in total collagen volume fraction without a change in architecture leaves systolic and passive diastolic function unaltered. A prolongation of relaxation was present in aortic stenosis and appears to be mediated by muscle hypertrophy per se.