Impact of Tirofiban on Serum Troponin Changes in Patients Undergoing Carotid Artery Stenting: A Propensity Matched Analysis

BACKGROUND

The optional periprocedural antithrombotic management for carotid artery stenting (CAS) is still debated.

METHODS

We aimed to compare the procedural and 1-month outlook of patients undergoing CAS with tirofiban as parenteral antiplatelet therapy. We retrospectively compared patients receiving tirofiban during CAS versus those undergoing CAS without tirofiban, using propensity score matching. Ancillary antithrombotic therapy included in all patients aspirin, clopidogrel, and unfractioned heparin. The primary outcome was the change in serum troponin from baseline to postprocedural peak levels. A total of 30 patients undergoing CAS were included, 15 receiving tirofiban on top of heparin and dual oral antiplatelet therapy (DAPT) and 15 receiving only heparin and DAPT. Bail-out use of tirofiban was an exclusion criterion.

RESULTS

Baseline troponin was 3.00 (0.06; 5.20) ng/mL in the tirofiban group vs. 4.6 (0.02; 13.10) ng/mL in the no-tirofiban group (P = 0.229), and postprocedural peak 3.5 (0.06; 5.50) ng/mL vs. 6.30 (0.09; 28.40) ng/mL (P = 0.191). Peak-baseline difference in troponin was lower in the tirofiban group than in the no-tirofiban group: 0.3 (0.00; 1.7) ng/mL vs. 1.3 (0.01; 10.00) ng/mL (P = 0.044); the relative peak-baseline change in troponin was analogously different: 24.3% (0%; 44.7%) vs. 50% (21.3%; 80.0%) (P = 0.039). No case of death, myocardial infarction, stroke, or transient ischemic attack occurred during in-hospital stay or at 1-month follow-up.

CONCLUSIONS

Tirofiban during CAS might provide periprocedural myocardial protection and reduce myocardial injury as determined by serial troponin measurements.

Comparison of Biolimus Versus Everolimus for Drug-Eluting Stents in the Percutaneous Treatment of Infra-Inguinal Arterial Disease

BACKGROUND

Drug-eluting stents (DES) are now considered the most promising device to treat peripheral artery disease (PAD) and minimize restenosis. There is uncertainty however on the best antirestenotic drug for such devices. In particular, biolimus (i.e. umirolimus) and everolimus are two of the most promising agents, given the extensive data in support of their coronary safety and efficacy, but their comparative effectiveness for peripheral interventions is not established.

METHODS

Building upon our extensive experience in the percutaneous treatment of infra-inguinal artery disease with DES, we compared the acute and longterm outlook of patients treated with biolimus-eluting stents (BES) and everolimus-eluting stents (EES). We collected baseline, procedural and outcome details on all patients undergoing infra-inguinal BES or EES implantation. The endpoints of interest were death, amputation, revascularization, their composite, and change in Fontaine class. A total of 80 patients were included (20 treated with BES and 60 with EES). Most features were similar in the two groups, despite longer lesions in the EES group. Unadjusted analysis showed similar results irrespective of the drug used, with composite endpoint occurring, respectively, in 4 (20.0%) and 10 (16.7%) (p=0.741).

RESULTS AND CONCLUSION

However, analysis with inverse probability of treatment weighting showed significant differences in the risk of revascularization (hazard ratio of BES vs EES=9.55 [95% confidence interval 2.16-42.23], p=0.003) and composite endpoint (hazard ratio=5.11 [1.33-19.62], p=0.018). In conclusion, EES appear superior to BES for endovascular therapy of infrainguinal artery disease. Dedicated randomized trials are required to definitely confirm or disprove these findings.

Endovascular Therapy for Infrainguinal Artery Disease With Coronary Devices

Several devices are available for infrainguinal endovascular therapy, with drug-eluting stents (DES) among the most promising. Bioresorbable vascular scaffolds (BVS) may further improve outcomes. We have liberally used in our practice coronary DES and BVS for infrainguinal endovascular therapy and hereby report our preliminary results. We conducted an observational study by retrospectively identifying characteristics of patients undergoing infrainguinal implantation of coronary DES or BVS. We compared the risk of major adverse events (MAE: death, amputation, or target vessel revascularization [TVR]) and components of MAE in the overall sample and after propensity matching. We included a total of 204 patients (207 limbs), 148 (72.5%) treated with DES and 56 (27.5%) with BVS. Bivariate analysis showed that TVR was less common in the DES group (41.9% vs 18.4%, P = .014). However, propensity-matched analysis showed nearly identical risks of MAE, amputation, TVR, or symptom burden with DES and BVS (all P > .05). In conclusion, the present pilot experience with coronary BVS suggests that they could provide acceptable results for infrainguinal endovascular procedures, comparable to those obtained by their metallic counterpart.

Endovascular Therapy for Infrainguinal Artery Disease With Coronary Devices: A Retrospective Observational Study Comparing Drug-Eluting Stents Versus Bioresorbable Vascular Scaffolds

Several devices are available for infrainguinal endovascular therapy, with drug-eluting stents (DES) among the most promising. Bioresorbable vascular scaffolds (BVS) may further improve outcomes. We have liberally used in our practice coronary DES and BVS for infrainguinal endovascular therapy and hereby report our preliminary results. We conducted an observational study by retrospectively identifying characteristics of patients undergoing infrainguinal implantation of coronary DES or BVS. We compared the risk of major adverse events (MAE: death, amputation, or target vessel revascularization [TVR]) and components of MAE in the overall sample and after propensity matching. We included a total of 204 patients (207 limbs), 148 (72.5%) treated with DES and 56 (27.5%) with BVS. Bivariate analysis showed that TVR was less common in the DES group (41.9% vs 18.4%, P = .014). However, propensity-matched analysis showed nearly identical risks of MAE, amputation, TVR, or symptom burden with DES and BVS (all P > .05). In conclusion, the present pilot experience with coronary BVS suggests that they could provide acceptable results for infrainguinal endovascular procedures, comparable to those obtained by their metallic counterpart.

Tirofiban counteracts endothelial cell apoptosis through the VEGF/VEGFR2/pAkt axis

Tirofiban is used in the treatment of patients with acute coronary syndrome submitted to percutaneous coronary intervention (PCI). We have, previously, shown that tirofiban stimulates VEGF expression and promotes proliferation of endothelial cells. VEGF is a well known inhibitor of endothelial cell apoptosis. TNF-α is a pro-apoptotic cytokine released in the site of a vascular injury, including balloon angioplasty. We thought to investigate whether tirofiban was able to protect endothelial cells from cell death induced by TNF-α. For this study, we used human umbilical vein endothelial cells (HUVEC). Analysis of apoptosis was performed by propidium iodide incorporation, annexin V staining and measure of active caspase 3 levels. Western blot served for a semiquantitative measure of Akt activation, VEGF, and the pro-apoptotic Bim and Bak. Our results show that TNF-α was unable to activate caspase 3 and produce cell death in the presence of tirofiban. Activation of apoptosis was preceded by upregulation of Bim and Bak that resulted decreased after addition of tirofiban. The anti-apoptosis effect of tirofiban was reproduced by VEGF and counteracted by VEGFR2 blockade and the cation chelating agent ethylene glycol tetraacetic acid (EGTA). The use of p-Akt inhibitor, BEZ235,and Akt knockdown, suggested that pAkt mediated the prosurvival effect of tirofiban. In conclusion, tirofiban protects endothelial cells from apoptosis stimulated by TNF-α, due to its ability to stimulate VEGF production.

The combination of transcriptomics and informatics identifies pathways targeted by miR-204 during neurogenesis and axon guidance

Vertebrate organogenesis is critically sensitive to gene dosage and even subtle variations in the expression levels of key genes may result in a variety of tissue anomalies. MicroRNAs (miRNAs) are fundamental regulators of gene expression and their role in vertebrate tissue patterning is just beginning to be elucidated. To gain further insight into this issue, we analysed the transcriptomic consequences of manipulating the expression of miR-204 in the Medaka fish model system. We used RNA-Seq and an innovative bioinformatics approach, which combines conventional differential expression analysis with the behavior expected by miR-204 targets after its overexpression and knockdown. With this approach combined with a correlative analysis of the putative targets, we identified a wider set of miR-204 target genes belonging to different pathways. Together, these approaches confirmed that miR-204 has a key role in eye development and further highlighted its putative function in neural differentiation processes, including axon guidance as supported by in vivo functional studies. Together, our results demonstrate the advantage of integrating next-generation sequencing and bioinformatics approaches to investigate miRNA biology and provide new important information on the role of miRNAs in the control of axon guidance and more broadly in nervous system development.

miR-204 targeting of Ankrd13A controls both mesenchymal neural crest and lens cell migration

Loss of cell adhesion and enhancement of cell motility contribute to epithelial-to-mesenchymal transition during development. These processes are related to a) rearrangement of cell-cell and cell-substrate adhesion molecules; b) cross talk between extra-cellular matrix and internal cytoskeleton through focal adhesion molecules. Focal adhesions are stringently regulated transient structures implicated in cell adhesion, spreading and motility during tissue development. Importantly, despite the extensive elucidation of the molecular composition of focal adhesions, the complex regulation of their dynamics is largely unclear. Here, we demonstrate, using live-imaging in medaka, that the microRNA miR-204 promotes both mesenchymal neural crest and lens cell migration and elongation. Overexpression of miR-204 results in upregulated cell motility, while morpholino-mediated ablation of miR-204 activity causes abnormal lens morphogenesis and neural crest cell mislocalization. Using a variety of in vivo and in vitro approaches, we demonstrate that these actions are mediated by the direct targeting of the Ankrd13A gene, which in turn controls focal cell adhesion formation and distribution. Significantly, in vivo restoration of abnormally elevated levels of Ankrd13A resulting from miR-204 inactivation rescued the aberrant lens phenotype in medaka fish. These data uncover, for the first time in vivo, the role of a microRNA in developmental control of mesenchymal cell migration and highlight miR-204 as a "master regulator" of the molecular networks that regulate lens morphogenesis in vertebrates.

Pax6 regulates gene expression in the vertebrate lens through miR-204

During development, tissue-specific transcription factors regulate both protein-coding and non-coding genes to control differentiation. Recent studies have established a dual role for the transcription factor Pax6 as both an activator and repressor of gene expression in the eye, central nervous system, and pancreas. However, the molecular mechanism underlying the inhibitory activity of Pax6 is not fully understood. Here, we reveal that Trpm3 and the intronic microRNA gene miR-204 are co-regulated by Pax6 during eye development. miR-204 is probably the best known microRNA to function as a negative modulator of gene expression during eye development in vertebrates. Analysis of genes altered in mouse Pax6 mutants during lens development revealed significant over-representation of miR-204 targets among the genes up-regulated in the Pax6 mutant lens. A number of new targets of miR-204 were revealed, among them Sox11, a member of the SoxC family of pro-neuronal transcription factors, and an important regulator of eye development. Expression of Trpm/miR-204 and a few of its targets are also Pax6-dependent in medaka fish eyes. Collectively, this study identifies a novel evolutionarily conserved mechanism by which Pax6 controls the down-regulation of multiple genes through direct up-regulation of miR-204.

The transcription factor Pax6 is reiteratively employed in space and time for the establishment of progenitor pools and the differentiation of neuronal and non-neuronal lineages of the CNS, pancreas, and eye. Execution of these diverse developmental programs depends on simultaneous activation and repression of gene networks functioning downstream of Pax6. MicroRNAs function as inhibitors of gene expression. Many microRNA genes are transcribed through common promoters of host genes. In this study, using wide-scale analysis of changes in gene expression following Pax6 deletion in the lens, we discover that Pax6 regulates the gene Trpm3 and its hosted microRNA, miR-204. We then show that miR-204 suppresses several target genes in the lens, notably the neuronal gene Sox11. Lastly, by conducting parallel experiments in the medaka fish, we show that Pax6 control of miR-204 and its target genes is evolutionarily conserved between mammals and fish, stressing the biological importance of this pathway. Pax6 regulation of miR-204 explains part of the complex, divergent inhibitory activity of Pax6 in ocular progenitor cells, which is required to establish and maintain the identity and function of ocular tissues.

Vax2 regulates retinoic acid distribution and cone opsin expression in the vertebrate eye

Vax2 is an eye-specific homeobox gene, the inactivation of which in mouse leads to alterations in the establishment of a proper dorsoventral eye axis during embryonic development. To dissect the molecular pathways in which Vax2 is involved, we performed a transcriptome analysis of Vax2(-/-) mice throughout the main stages of eye development. We found that some of the enzymes involved in retinoic acid (RA) metabolism in the eye show significant variations of their expression levels in mutant mice. In particular, we detected an expansion of the expression domains of the RA-catabolizing enzymes Cyp26a1 and Cyp26c1, and a downregulation of the RA-synthesizing enzyme Raldh3. These changes determine a significant expansion of the RA-free zone towards the ventral part of the eye. At postnatal stages of eye development, Vax2 inactivation led to alterations of the regional expression of the cone photoreceptor genes Opn1sw (S-Opsin) and Opn1mw (M-Opsin), which were significantly rescued after RA administration. We confirmed the above described alterations of gene expression in the Oryzias latipes (medaka fish) model system using both Vax2 gain- and loss-of-function assays. Finally, a detailed morphological and functional analysis of the adult retina in mutant mice revealed that Vax2 is necessary for intraretinal pathfinding of retinal ganglion cells in mammals. These data demonstrate for the first time that Vax2 is both necessary and sufficient for the control of intraretinal RA metabolism, which in turn contributes to the appropriate expression of cone opsins in the vertebrate eye.

MicroRNA target prediction by expression analysis of host genes

MicroRNAs (miRNAs) are small noncoding RNAs that control gene expression by inducing RNA cleavage or translational inhibition. Most human miRNAs are intragenic and are transcribed as part of their hosting transcription units. We hypothesized that the expression profiles of miRNA host genes and of their targets are inversely correlated and devised a novel procedure, HOCTAR (host gene oppositely correlated targets), which ranks predicted miRNA target genes based on their anti-correlated expression behavior relative to their respective miRNA host genes. HOCTAR is the first tool for systematic miRNA target prediction that utilizes the same set of microarray experiments to monitor the expression of both miRNAs (through their host genes) and candidate targets. We applied the procedure to 178 human intragenic miRNAs and found that it performs better than currently available prediction softwares in pinpointing previously validated miRNA targets. The high-scoring HOCTAR predicted targets were enriched in Gene Ontology categories, which were consistent with previously published data, as in the case of miR-106b and miR-93. By means of overexpression and loss-of-function assays, we also demonstrated that HOCTAR is efficient in predicting novel miRNA targets and we identified, by microarray and qRT-PCR procedures, 34 and 28 novel targets for miR-26b and miR-98, respectively. Overall, we believe that the use of HOCTAR significantly reduces the number of candidate miRNA targets to be tested compared to the procedures based solely on target sequence recognition. Finally, our data further confirm that miRNAs have a significant impact on the mRNA levels of most of their targets.

Rapamycin antagonizes NF-kappaB nuclear translocation activated by TNF-alpha in primary vascular smooth muscle cells and enhances apoptosis

Several lines of evidence support the view that rapamycin inhibits NF-kappaB. TNF-alpha, a potent inducer of NF-kappaB, is released after artery injury (e.g., balloon angioplasty) and plays an important role in inflammation and restenosis. We investigated the effect of rapamycin on NF-kappaB activation and apoptosis in vascular smooth muscle cells (VSMCs) stimulated with TNF-alpha. Using EMSA, we found that TNF-alpha caused NF-kappaB nuclear translocation in VSMCs after 1 h of incubation. Rapamycin inhibited IkappaBalpha degradation, thereby preventing nuclear translocation. Activation of NF-kappaB was accompanied by an increase of Bcl-xL and Bfl-1/A1 proteins, detected by Western blot assay, whereas rapamycin prevented the TNF-alpha-induced enhancement of these antiapoptotic proteins. The extent of apoptosis of VSMCs exposed to TNF-alpha was significantly enhanced by rapamycin. The effect of rapamycin appeared to be independent of the phosphatidylinositol 3-kinase/Akt-protein kinase B survival pathway, because the phosphatidylinositol 3-kinase inhibitor wortmannin neither prevented IkappaBalpha degradation nor increased apoptosis of cells incubated with TNF-alpha. Finally, we demonstrate that the large immunophilin FK-506 binding protein FKBP51 is essential for TNF-alpha-induced NF-kappaB activation in VSMCs. Our findings show that rapamycin inhibits NF-kappaB activation and acts in concert with TNF-alpha in induction of VSMC apoptosis.

Rapamycin stimulates apoptosis of childhood acute lymphoblastic leukemia cells

The phosphatidyl-inositol 3 kinase (PI3k)/Akt pathway has been implicated in childhood acute lymphoblastic leukemia (ALL). Because rapamycin suppresses the oncogenic processes sustained by PI3k/Akt, we investigated whether rapamycin affects blast survival. We found that rapamycin induces apoptosis of blasts in 56% of the bone marrow samples analyzed. Using the PI3k inhibitor wortmannin, we show that the PI3k/Akt pathway is involved in blast survival. Moreover, rapamycin increased doxorubicin-induced apoptosis even in nonresponder samples. Anthracyclines activate nuclear factor kappaB (NF-kappaB), and disruption of this signaling pathway increases the efficacy of apoptogenic stimuli. Rapamycin inhibited doxorubicin-induced NF-kappaB in ALL samples. Using a short interfering (si) RNA approach, we demonstrate that FKBP51, a large immunophilin inhibited by rapamycin, is essential for drug-induced NF-kappaB activation in human leukemia. Furthermore, rapamycin did not increase doxorubicin-induced apoptosis when NF-kappaB was overexpressed. In conclusion, rapamycin targets 2 pathways that are crucial for cell survival and chemoresistance of malignant lymphoblasts--PI3k/Akt through the mammalian target of rapamycin and NF-kappaB through FKBP51--suggesting that the drug could be beneficial in the treatment of childhood ALL.

Rapamycin inhibits doxorubicin-induced NF-kappaB/Rel nuclear activity and enhances the apoptosis of melanoma cells

Inhibition of nuclear factor (NF)-kappaB/Rel can sensitise many tumour cells to death-inducing stimuli, including chemotherapeutic agents, and there are data suggesting that disruption of NF-kappaB may be of therapeutic interest in melanoma. We found that rapamycin sensitised a human melanoma cell line, established from a patient, to the cytolytic effects of doxorubicin. Doxorubicin is a striking NF-kappaB/Rel-inducer, we therefore investigated if rapamycin interfered with the pathway of NF-kappaB/Rel activation, i.e. IkappaBalpha-phosphorylation, -degradation and NF-kappaB/Rel nuclear translocation, and found that the macrolide agent caused a block of IKK kinase activity that was responsible for a reduced nuclear translocation of transcription factors. Western blots for Bcl-2 and c-IAP1 showed increased levels of these anti-apoptotic proteins in cells incubated with doxorubicin, in accordance with NF-kappaB/Rel activation, while rapamycin clearly downmodulated these proteins, in line with its pro-apoptotic ability. The effect of the macrolide on NF-kappa B/Rel induction appeared to be independent of the block in the PI3k/Akt pathway, because it could not be reproduced by the phosphatidyl inositol 3 kinase (PI3k) inhibitor, wortmannin. Recently, the immunophilin, FKBP51, has been shown to be essential for the function of IKK kinase. We found high expression levels of FKBP51 in melanoma cells. Moreover, we confirmed the involvement of this immunophilin in the control of IKK activity. Indeed, IkappaBalpha could not be degraded when FKBP51 was downmodulated by short-interfering RNAs (siRNAs). These findings provide a possible mechanism for the downmodulation of NF-kappaB by rapamycin, since the macrolide agent specifically inhibits FKBP51 isomerase activity. In conclusion, our study demonstrates that rapamycin blocked NF-kappaB/Rel activation independently of PI3k/Akt inhibition suggesting that the macrolide agent could synergise with NF-kappaB-inducing anti-cancer drugs in PTEN-positive tumours.