[Clinical pharmacology of current antiplatelet drugs]. / Klinische Pharmakologie der aktuellen antithrombozytären Substanzen.

Dual antiplatelet therapy with low-dose acetylsalicylic acid (ASA) and an inhibitor of the P2Y12 adenosine diphosphate (ADP) receptor is the standard treatment for patients presenting with acute coronary syndrome (ACS) or undergoing elective coronary interventions according to the current guidelines published by the European Society of Cardiology (ESC). New generation P2Y12 inhibitors, such as prasugrel and ticagrelor exert stronger and more consistent inhibition of the P2Y12 receptor. In clinical studies enrolling patients with ACS these drugs decreased the incidence of ischemic events compared to the standard therapy with clopidogrel and ASA; however, this beneficial effect was associated with an increase in bleeding events. Alternative therapeutic approaches via addition of drugs with different modes of action showed an overall reduction of ischemic events but also failed to uncouple this beneficial effect from an increased bleeding risk.

Micro-array profiling exhibits remarkable intra-individual stability of human platelet micro-RNA.

Platelets play an important role in haemostasis and thrombus formation. Latest research identified platelets harbouring so called microRNAs (miRNA). MiRNAs are short single-stranded RNAs modulating gene expression by targeting mRNAs. Limited data exist on inter-individual variability of platelet miRNA profile while no data are available on intra-individual variability. We assessed platelet miRNA profile in five volunteers at five time points over a time course of 10 days; 24 hours prior to the last blood sampling, subjects took 500 mg acetylsalicylic acid (ASA). Platelet miRNA was isolated from leucocyte-depleted platelet-rich plasma, and miRNA array-analysis was performed. Temporal patterns and ASA effect were explored by a linear mixed effects model for each miRNA. For the 20 most abundantly expressed platelet miRNAs, target gene search was performed and an annotation network was created. MiRNA expression profiling of 1,281 human miRNAs revealed relevant expression of 221 miRNAs consistently expressed in all samples at all time points. Correlation of platelet miRNA ranks was highly significant to other studies. Global distribution of miRNA expression was relatively similar in all subjects. No miRNA exhibited a significant effect of time at level 0.05. After 24 hours, no significant effect of ASA was found. Concerning functional implications of the 20 most abundantly expressed miRNAs, we found six functional themes. In conclusion, platelet miRNA profile is remarkably stable over the time period studied. Single-point analysis of platelet miRNA profile is reasonable when inter-individual differences are studied. The functional annotation network points toward extra-platelet effects of platelet miRNAs.

Transcriptome analysis reveals a role of interferon-gamma in human neointima formation.

The most effective immediate cure for coronary stenosis is stent-supported angioplasty. Restenosis due to neointima proliferation represents a major limitation. We investigated the expression of 2435 genes in atherectomy specimens and blood cells of patients with restenosis, normal coronary artery specimens, and cultured human smooth muscle cells (SMCs). Of the 223 differentially expressed genes, 37 genes indicated activation of interferon-gamma (IFN-gamma) signaling in neointimal SMCs. In cultured SMCs, IFN-gamma inhibited apoptosis. Genetic disruption of IFN-gamma signaling in a mouse model of restenosis significantly reduced the vascular proliferative response. Our data suggest an important role of IFN-gamma in the control of neointima proliferation.

Gene expression profiling of human stent-induced neointima by cDNA array analysis of microscopic specimens retrieved by helix cutter atherectomy: Detection of FK506-binding protein 12 upregulation.

BACKGROUND: Restenosis due to neointima formation is the major limitation of stent-supported balloon angioplasty. Despite abundant animal data, molecular mechanisms of neointima formation have been investigated on only a limited basis in patients. This study sought to establish a method for profiling gene expression in human in-stent neointima and to identify differentially expressed genes that may serve as novel therapeutic targets. METHODS AND RESULTS: We retrieved tissue specimens from patients with symptomatic in-stent restenosis using a novel helix cutter atherectomy device. cDNA samples prepared from neointima (n=10) and, as a control, from the media of normal arteries (n=14) were amplified using a novel polymerase chain reaction protocol and hybridized to cDNA arrays. Immunohistochemistry characterized the atherectomy material as neointima. cDNA arrays readily identified differentially expressed genes. Some of the differentially expressed genes complied with expected gene expression patterns of neointima, including downregulation of desmin and upregulation of thrombospondin-1, cyclooxygenase-1, and the 70-kDa heat shock protein B. Additionally, we discovered previously unknown gene expression patterns, such as downregulation of mammary-derived growth inhibitor and upregulation of FK506-binding protein 12 (FKBP12). Upregulation of FKBP12 was confirmed at the protein level in neointimal smooth muscle cells. CONCLUSIONS: Gene expression patterns of human neointima retrieved by helix-cutter atherectomy can be reliably analyzed by cDNA array technology. This technique can identify therapeutic targets in patients, as exemplified by the findings regarding FKBP12. FKBP12 is the receptor for Rapamycin (sirolimus), which in animal models reduced neointima formation. Our study thus yields a rationale for the use of Rapamycin to prevent restenosis in patients.