Effects of Oral Prednisone After Stenting in a Rabbit Model of Established Atherosclerosis

Value of Absolute Eosinophil Count in Patients with Acute Coronary Syndrome Undergoing Percutaneous Coronary Intervention

Background and Aims

Elevated eosinophils typically indicate hypersensitive inflammation; however, their involvement in cardiovascular events remains incompletely understood. We investigated the association between the absolute eosinophil count (AEC) and major adverse cardiovascular and cerebrovascular events (MACCEs) in patients with acute coronary syndrome (ACS) undergoing percutaneous coronary intervention (PCI). Additionally, we determine whether the integration of AEC with the SYNTAX II score could improve predictive ability.

Methods and Results

The AECs of 1711 patients with ACS undergoing PCI from June 2016 to November 2017 were analyzed on admission. All recruitments were splitted into three groups based on AEC tertiles and 101 participants underwent one or more noteworthy outcomings. The association between AEC and MACCEs (defined as a composite of cardiovascular death, myocardial infarction [MI], and stroke) was tested by Cox proportional-hazards regression analysis. After adjusting for confounders, AEC was independently associated with MACCEs (HR 11.555, 95% CI: 3.318-40.239). Patients in the lowest AEC tertile (T1) as a reference, those in the higher tertiles had an incrementally higher risk of MACCEs (T3: HR 1.848 95% CI: 1.157-2.952; P for trend=0.008). Inclusion of AEC enhanced the predictive accuracy of the SYNTAX II score for MACCEs (AUC: from 0.701 [95% CI: 0.646-0.756] to 0.728 [95% CI: 0.677-0.780]; DeLong's test, P = 0.020).

Conclusion

AEC is independently linked to MACCEs in ACS patients who underwent PCI, and adds incremental predictive information to the SYNTAX II score.

Methotrexate Therapy Promotes Cell Coverage and Stability in in-Stent Neointima

PURPOSE

Anti-proliferative drugs released from drug-eluting stents delay cell coverage and vascular healing, which increases the risk of late stent thrombosis. We assessed the potential effects of systemic methotrexate (MTX) on cell coverage, vascular healing and inflammation activation in vivo and in vitro.

METHODS

We applied MTX in the right common carotid artery in a rabbit stenting model to determine the impact on cell coverage and inflammation activation using a serial optical coherence tomography (OCT) analysis and elucidated the molecular mechanism of MTX in human umbilical vein endothelial cells (HUVECs).

RESULTS

Low-dose MTX promoted the development of cell coverage and vascular healing, which was associated with fewer uncovered struts (%) and cross-sections with any uncovered struts (%) at 4 weeks of stenting. The MTX group also exhibited lower rates of heterogeneity, microvessels and per-strut low-signal-intensity layers, indicating neointimal instability at 12 weeks of stenting. In vitro, low-dose MTX strongly inhibited HUVEC apoptosis, promoted proliferation and inhibited inflammatory activation by targeting the phosphoinositide 3-kinase (PI3K)/AKT signalling pathway.

CONCLUSION

Low-dose MTX may be a key means of promoting early cell coverage via the inhibition of the inflammatory response and stability of neointima by targeting inflammatory pathways after stent implantation.

Effects of high doses of glucocorticoids on insulin-mediated vasodilation in the mesenteric artery of rats

Several pathological conditions predict the use of glucocorticoids for the management of the inflammatory response; however, chronic or high dose glucocorticoid treatment is associated with hyperglycemia, hyperlipidemia, and insulin resistance and can be considered a risk factor for cardiovascular disease. Therefore, we investigated the mechanisms involved in the vascular responsiveness and inflammatory profile of mesenteric arteries of rats treated with high doses of glucocorticoids. Wistar rats were divided into a control (CO) group and a dexamethasone (DEX) group, that received dexamethasone for 7 days (2mg/kg/day, i.p.). Blood samples were used to assess the lipid profile and insulin tolerance. Vascular reactivity to Phenylephrine (Phe) and insulin, and O2•-production were evaluated. The intracellular insulin signaling pathway PI3K/AKT/eNOS and MAPK/ET-1 were investigated. Regarding the vascular inflammatory profile, TNF-α, IL-6, IL-1β and IL-18 were assessed. Dexamethasone-treated rats had decreased insulin tolerance test and endothelium-dependent vasodilation induced by insulin. eNOS inhibition caused vasoconstriction in the DEX group, which was abolished by the ET-A antagonist. Insulin-mediated relaxation in the DEX group was restored in the presence of the O2.- scavenger TIRON. Nevertheless, in the DEX group there was an increase in Phe-induced vasoconstriction. In addition, the intracellular insulin signaling pathway PI3K/AKT/eNOS was impaired, decreasing NO bioavailability. Regarding superoxide anion generation, there was an increase in the DEX group, and all measured proinflammatory cytokines were also augmented in the DEX group. In addition, the DEX-group presented an increase in low-density lipoprotein cholesterol (LDL-c) and total cholesterol (TC) and reduced high-density lipoprotein cholesterol (HDL-c) levels. In summary, treatment with high doses of dexamethasone promoted changes in insulin-induced vasodilation, through the reduction of NO bioavailability and an increase in vasoconstriction via ET-1 associated with generation of O2•- and proinflammatory cytokines.

Glucocorticoids are active players and therapeutic targets in atherosclerotic cardiovascular disease

Adrenal-derived glucocorticoids mediate the physiological response to stress. Chronic disturbances in glucocorticoid homeostasis, i.e. in Addison's and Cushing's disease patients, predispose to the development of atherosclerotic cardiovascular disease. Here we review preclinical and clinical findings regarding the relation between changes in plasma glucocorticoid levels and the atherosclerosis extent. It appears that, although the altered glucocorticoid function can in most cases be restored in the different patient groups, current therapies do not necessarily reverse the associated risk for atherosclerotic cardiovascular disease. In our opinion much attention should therefore be given to the development of a Cushing's disease mouse model that can (1) effectively replicate the effect of hypercortisolemia on atherosclerosis outcome observed in humans and (2) be used to investigate, in a preclinical setting, the relative impact on atherosclerosis susceptibility of already available (e.g. metyrapone) and potentially novel (i.e. SR-BI activity modulators) therapeutic agents that target the adrenal glucocorticoid output.

Interleukin-35 promotes early endothelialization after stent implantation by regulating macrophage activation

Background: Early strut coverage after sirolimus-eluting stent (SES) implantation is associated with the activation of inflammation, but the underlying mechanisms are not completely understood. The present study aimed to identify the relationship between the anti-inflammatory cytokine interleukin (IL) 35 (IL-35) and early strut coverage in vivo and in vitro.

Methods: We utilized a retrospective study design to measure IL-35 levels in 68 stents from 68 patients with coronary artery disease and recorded serial optical coherence tomography (OCT) images (0 and 3 months) to assess stent endothelialization. The mechanism underlying the regulatory effects of IL-35 on macrophages and human umbilical vein endothelial cells (HUVECs) was also investigated. SESs were surgically implanted into the right common carotid arteries of 200 male New Zealand White rabbits receiving intravenous injections of IL-35 or a placebo.

Results: At the 3-month OCT evaluation, complete endothelium coverage was correlated with IL-35 levels. IL-35 induced the activation of an anti-inflammatory M2-like macrophage phenotype by targeting the signal transducer and activators of transcription (STAT)1/4 signalling pathway, and IL-35-treated macrophages induced endothelial proliferation and alleviated endothelial dysfunction. IL-35-treated New Zealand White rabbits with implanted SESs showed lower percentages of cross-sections with an uncovered strut, elevated mean neointimal hyperplasia (NIH) thickness, and inhibited inflammatory responses.

Conclusions: We investigated the effect of IL-35 expression on early stent endothelialization in vivo and in vitro and identified a crucial role for IL-35 in inducing the activation of an anti-inflammatory M2-like macrophage phenotype. The present study highlights a new therapeutic strategy for early stent endothelialization.

A Rabbit Model of Durable Transgene Expression in Jugular Vein to Common Carotid Artery Interposition Grafts

Vein graft bypass surgery is a common treatment for occlusive arterial disease; however, long-term success is limited by graft failure due to thrombosis, intimal hyperplasia, and atherosclerosis. The goal of this article is to demonstrate a method for placing bilateral venous interposition grafts in a rabbit, then transducing the grafts with a gene transfer vector that achieves durable transgene expression. The method allows the investigation of the biological roles of genes and their protein products in normal vein graft homeostasis. It also allows the testing of transgenes for the activities that could prevent vein graft failure, e.g., whether the expression of a transgene prevents the neointimal growth, reduces the vascular inflammation, or reduces atherosclerosis in rabbits fed with a high-fat diet. During an initial survival surgery, the segments of right and left external jugular vein are excised and placed bilaterally as reversed end-to-side common carotid artery interposition grafts. During a second survival surgery, performed 28 days later, each of the grafts is isolated from the circulation with vascular clips and the lumens are filled (via an arteriotomy) with a solution containing a helper-dependent adenoviral (HDAd) vector. After a 20-min incubation, the vector solution is aspirated, the arteriotomy is repaired, and flow is restored. The veins are harvested at time points dictated by individual experimental protocols. The 28-day delay between the graft placement and the transduction is necessary to ensure the adaptation of the vein graft to the arterial circulation. This adaptation avoids rapid loss of transgene expression that occurs in vein grafts transduced before or immediately after grafting. The method is unique in its ability to achieve durable, stable transgene expression in grafted veins. Compared to other large animal vein graft models, rabbits have advantages of low cost and easy handling. Compared to rodent vein graft models, rabbits have larger and easier-to-manipulate blood vessels that provide abundant tissue for analysis.

Local adventitial anti-angiogenic gene therapy reduces growth of vasa-vasorum and in-stent restenosis in WHHL rabbits

BACKGROUND

Antiproliferative drugs in drug eluting stents (DES) are associated with complications due to impaired re-endothelialization. Additionally, adventitial neovascularization has been suggested to contribute to in-stent restenosis (ISR). Since Vascular Endothelial Growth Factors (VEGFs) are the key mediators of angiogenesis, we investigated feasibility and efficacy of local gene therapy for ISR utilizing soluble decoy VEGF receptors to reduce biological activity of adventitial VEGFs.

METHOD

Sixty-nine adult WHHL rabbit aortas were subjected to endothelial denudation. Six weeks later catheter-mediated local intramural infusion of 1.5x10e10 pfu adenoviruses encoding soluble VEGF Receptor-1 (sVEGFR1), sVEGFR2, sVEGFR3 or control LacZ and bare metal stent implantation were performed in the same aortic segment. Marker protein expression was assessed at 6d in LacZ cohort. Immunohistochemistry, morphometrical analyses and angiography were performed at d14, d42 and d90.

RESULTS

Transgene expression was localized to adventitia. All decoy receptors reduced the size of vasa-vasorum at 14d, AdsVEGFR2 animals also had reduced density of adventitial vasa-vasorum, whereas AdsVEGFR3 increased the density of vasa-vasorum. At d42, AdsVEGFR1 and AdsVEGFR2 reduced ISR (15.7 ± 6.9% stenosis, P < 0.01 and 16.5 ± 2.7%, P < 0.05, respectively) vs. controls (28.3 ± 7.6%). Moreover, AdsVEGFR-3 treatment led to a non-significant trend in the reduction of adventitial lymphatics at all time points and these animals had significantly more advanced neointimal atherosclerosis at 14d and 42d vs. control animals.

CONCLUSIONS

Targeting adventitial neovascularization using sVEGFR1 and sVEGFR2 is a novel strategy to reduce ISR. The therapeutic effects dissipate at late follow up following short expression profile of adenoviral vectors. However, inhibition of VEGFR3 signaling accelerates neoatherosclerosis.

Glucocorticoids and endothelial function in inflammatory diseases: focus on rheumatoid arthritis

Rheumatoid arthritis (RA) is the most common systemic autoimmune disease characterized by articular and extra-articular manifestations involving cardiovascular (CV) diseases. RA increases the CV mortality by up to 50 % compared with the global population and CV disease is the leading cause of death in patients with RA. There is growing evidence that RA favors accelerated atherogenesis secondary to endothelial dysfunction (ED) that occurs early in the course of the disease. ED is a functional and reversible alteration of endothelial cells, leading to a shift of the actions of the endothelium towards reduced vasodilation, proinflammatory state, proliferative and prothrombotic properties. The mechanistic links between RA and ED have not been fully explained, but growing evidence suggests a role for traditional CV factors, auto-antibodies, genetic factors, oxidative stress, inflammation and iatrogenic interventions such as glucocorticoids (GCs) use. GCs have been used in RA for several decades. Whilst their deleterious CV side effects were described in the 1950s, their effect on CV risk associated with inflammatory arthritis remains subject for debate. GC might induce negative effects on endothelial function, via a direct effect on endothelium or via increasing CV risk factors. Conversely, they might actually improve endothelial function by decreasing systemic and/or vascular inflammation. The present review summarizes the available data on the impact of GCs on endothelial function, both in normal and inflammatory conditions, with a special focus on RA patients.

Effects of Methotrexate in a Rabbit Model of In-Stent Neoatherosclerosis: An Optical Coherence Tomography Study

This study used optical coherence tomography (OCT) to investigate the effects of systemic methotrexate, in combination with a drug-eluting stent, on in-stent neoatherosclerosis in a rabbit model. Sirolimus-eluting stents were surgically implanted in the right common carotid arteries of 200 male New Zealand White rabbits; the animals received a high-fat diet, beginning one week before stent implantation. Each animal was randomly assigned to 1 of 4 groups, receiving intravenous injections of either methotrexate (0.4 mg/kg) or placebo weekly for 4 or 12 weeks. Stented arterial segments were harvested after stenting for 4 or 12 weeks, and processed for OCT and histological analysis. Prior to harvesting the arterial segments, blood was collected for the determinations of cytokine levels. Compared with the control animals, the methotrexate-treated animals showed lower rates of lipid-rich intima and per-strut low-signal intensity layers, smaller neointimal areas, and reduced neointimal thickness; larger fibrous cap thicknesses and smaller lumen areas were also seen in the animals receiving methotrexate. The levels of serum interleukin, adhesion molecules, and nuclear factor-κB p65 decreased and IL-10 level increased in the methotrexate-treated animals. Targeting the pro-inflammatory pathways may be an effective way to prevent restenosis without the long-term risk of late thrombosis.

Prednisolone- and sirolimus-eluting stent: Anti-inflammatory approach for inhibiting in-stent restenosis

Glucocorticoids are powerful anti-inflammatory, immunosuppressive, and anti-proliferative agents. The aim of this study was to evaluate the effectiveness of a prednisolone- (PDScs) and sirolimus-coated stent (SRLcs) in preventing artery vessel neointimal hyperplasia and inflammatory reactions in vitro and in vivo. PDS, a synthetic glucocorticoid, is a derivative of cortisol, which is used to treat a variety of inflammatory and autoimmune conditions. The stents were fabricated with PDS, SRL, or both agents using a layer-by-layer coating system (designated as PDScs, SRLcs, and PDSRLcs, respectively). The surface morphology of the PDScs showed an evenly dispersed and roughened shape, which was smoothened by the SRL coating. Half of the total drug amounts were released within seven days, followed by an additional release, which continued for up to 28 days. The proliferation of smooth muscle cells was inhibited in the SRLcs group (31.5 ± 4.08%), and this effect was enhanced by PDS addition (PDSRLcs, 46.8 ± 8.11%). Consistently, in the animal study, the restenosis rate was inhibited by the SRLcs and PDSRLcs (18.5 ± 6.23% and 14.5 ± 3.55%, respectively). Especially, fibrin expression and inflammation were suppressed in the PDS-containing group (PDScs, 0.6 ± 0.12 and 1.4 ± 0.33; PDSRLcs, 0.7 ± 0.48 and 1.7 ± 0.12, respectively) compared to PDS non-containing groups (BMS, 1.1 ± 0.12, and 1.8 ± 0.55; SRLcs, 1.6 ± 0.32 and 2.0 ± 0.62, respectively). Moreover, re-endothelialization was enhanced in the PDScs group as determined using immunohistochemistry with a cluster of differentiation (CD)-31 antibodies. These results suggest that the inhibitory effect of SRLcs on anti-restenosis can be accelerated by additional coating with PDS, which has promising properties as a bioactive compound with useful anti-inflammatory effects.

The epidemiology of asthma and its comorbidities in Poland--Health problems of patients with severe asthma as evidenced in the Province of Lodz

INTRODUCTION

Population studies supply interesting data regarding the epidemiology, comorbidity and risk factors of asthma, which have direct clinical implications for patients.

OBJECTIVES

The aim of the work was to evaluate the degree of severity of asthma in the studied group, the levels of anti-asthma treatment, the prevalence of asthma comorbidities and their influence on the clinical course of the illness.

PATIENTS AND METHODS

The study encompassed 451 participants: 52.11% were asthma patients (study group) and 47.89% were healthy subjects (controls). Respiratory function tests, ACT™ test and skin prick tests were performed.

RESULTS

Asthma severity was mild in 14.89%, moderate in 49.36% and severe in 35.74%. Oral GCS were used by 29%, inhalers 44%, LABA 68%, SABA 67%, LAMA 6%, SAMA 14% and MX 16%. Rhinitis and allergy were significantly more common in patients. GERD and neurological diseases were risk factors for asthma, and GERD significantly intensified the risk of severe asthma. GERD, atherosclerosis, hypertension, ischaemic heart disease and other cardiac diseases, lipid disorders, COPD, and the presence of any neoplastic disease significantly worsened the degree of asthma control.

DISCUSSION

Severe asthma was a significant clinical issue in over 35% of cases. The most commonly-used group of drugs were LABAs, while inhaled GCS and LAMA were uncommon, especially among severe cases. A significant problem was the high percentage of systemic GCS used by severe cases. The most important risk factor for asthma, including its severe form, is GERD. Numerous comorbid conditions significantly worsen the degree of asthma control.

Stent thrombosis caused by metal allergy complicated by protein S deficiency and heparin-induced thrombocytopenia: a case report and review of the literature

A 43-year-old woman recipient of a bare metal coronary stent during an acute anterior myocardial infarction was repeatedly hospitalized with recurrent stent thrombosis (ST) over the following 3 years. Emergent coronary angiography showed a thrombus in the in-stent segment of the proximal left anterior descending artery. We repeatedly aspirated the thrombus, which immediately reformed multiple times. The discontinuation of heparin and administration of thrombolytics and argatroban, followed by repeated balloon dilatations, ended the formation of new thrombi. The patient was found to be allergic to nickel, protein S deficient and carrier of heparin-induced thrombocytopenia antibody. We discuss this case in the context of a) literature pertaining to acute coronary syndromes in the young, and b) the detailed investigations needed to identify thrombotic risk factors. Steroids may be effective to prevent recurrent ST caused by stent allergy.

Effect of anti-ApoA-I antibody-coating of stents on neointima formation in a rabbit balloon-injury model

Background and Aims

Since high-density lipoprotein (HDL) has pro-endothelial and anti-thrombotic effects, a HDL recruiting stent may prevent restenosis. In the present study we address the functional characteristics of an apolipoprotein A-I (ApoA-I) antibody coating in vitro. Subsequently, we tested its biological performance applied on stents in vivo in rabbits.

Materials and Methods

The impact of anti ApoA-I- versus apoB-antibody coated stainless steel discs were evaluated in vitro for endothelial cell adhesion, thrombin generation and platelet adhesion. In vivo, response to injury in the iliac artery of New Zealand white rabbits was used as read out comparing apoA-I-coated versus bare metal stents.

Results

ApoA-I antibody coated metal discs showed increased endothelial cell adhesion and proliferation and decreased thrombin generation and platelet adhesion, compared to control discs. In vivo, no difference was observed between ApoA-I and BMS stents in lumen stenosis (23.3±13.8% versus 23.3±11.3%, p=0.77) or intima surface area (0.81±0.62 mm² vs 0.84±0.55 mm², p=0.85). Immunohistochemistry also revealed no differences in cell proliferation, fibrin deposition, inflammation and endothelialization.

Conclusion

ApoA-I antibody coating has potent pro-endothelial and anti-thrombotic effects in vitro, but failed to enhance stent performance in a balloon injury rabbit model in vivo.

Association between inflammatory biomarkers and in-stent restenosis tissue features: an Optical Coherence Tomography Study

AIMS

Inflammatory reaction after stent implantation is associated with in-stent restenosis (ISR). We assessed the association of optical coherence tomography (OCT) features of neointima with systemic levels of high-sensitivity C-reactive protein (hs-CRP) and eosinophil cationic protein (ECP) measured at the time of ISR detection.

METHODS AND RESULTS

Patients presenting with symptomatic angiographically documented ISR (diameter stenosis ≥ 50% by visual estimation) were included. Quantitative OCT analysis included the measurement of minimal lumen diameter, minimal luminal area, stent and neointimal area, stent and restenosis length, restenotic tissue burden, and symmetry ratio. Qualitative OCT analysis included the assessment of ISR plaque type, neointimal tissue structure, lumen shape, presence of microvessels and calcific nodules. At the time of ISR detection hs-CRP and ECP levels were measured, and statistical analysis was performed using as cut-off 3 mg/L and 4.5 µg/L, respectively. Our population included 40 patients, 24 bare metal stents and 16 drug-eluting stents. Patients with high hs-CRP levels had a higher restenostic tissue symmetry ratio (0.56 ± 0.17 vs. 0.42 ± 0.13, P = 0.01) when compared with patients with low hs-CRP levels. Patients with high ECP levels had a higher neointimal burden (70 ± 14 vs. 64 ± 11, P = 0.05) in comparison with patients with low ECP levels.

CONCLUSIONS

Inflammatory biomarkers assessed at the time of ISR detection are associated with different aspects of neointimal tissue. While hs-CRP seems to have a role in neointimal tissue shape, ECP is related to a neointimal burden.

Modulation of 11β-hydroxysteroid dehydrogenase as a strategy to reduce vascular inflammation

Atherosclerosis is a chronic inflammatory disease in which initial vascular damage leads to extensive macrophage and lymphocyte infiltration. Although acutely glucocorticoids suppress inflammation, chronic glucocorticoid excess worsens atherosclerosis, possibly by exacerbating systemic cardiovascular risk factors. However, glucocorticoid action within the lesion may reduce neointimal proliferation and inflammation. Glucocorticoid levels within cells do not necessarily reflect circulating levels due to pre-receptor metabolism by 11β-hydroxysteroid dehydrogenases (11β-HSDs). 11β-HSD2 converts active glucocorticoids into inert 11-keto forms. 11β-HSD1 catalyses the reverse reaction, regenerating active glucocorticoids. 11β-HSD2-deficiency/inhibition causes hypertension, whereas deficiency/inhibition of 11β-HSD1 generates a cardioprotective lipid profile and improves glycemic control. Importantly, 11β-HSD1-deficiency/inhibition is atheroprotective, whereas 11β-HSD2-deficiency accelerates atherosclerosis. These effects are largely independent of systemic risk factors, reflecting modulation of glucocorticoid action and inflammation within the vasculature. Here, we consider whether evidence linking the 11β-HSDs to vascular inflammation suggests these isozymes are potential therapeutic targets in vascular injury and atherosclerosis.

Eosinophilic responses to stent implantation and the risk of Kounis hypersensitivity associated coronary syndrome

The use of drug eluting stents constitutes a major breakthrough in current interventional cardiology because it is more than halves the need of repeat interventions. It is incontrovertible that coronary stents, in general, have been beneficial for the vast majority of patients. A small increase in thrombosis, following DES implantation, is offset by a diminished risk of complications associated with repeat vascularization. However, late and, especially, very late stent thrombosis is a much feared complication because it is associated with myocardial infarction with increased mortality. Despite that stent thrombosis is thought to be multifactorial, so far clinical reports and reported pathology findings in patients died from coronary stent thrombosis as well as animal studies and experiments, point toward a hypersensitivity inflammation. The stented and thrombotic areas are infiltrated by interacting, via bidirectional stimuli inflammatory cells including eosinophils, macrophages, T-cells and mast cells. Stented regions constitute an ideal surrounding for endothelial damage and dysfunction, together with hemorheologic changes and turbulence as well as platelet dysfunction, coagulation and fibrinolytic disturbances. Drug eluting stent components include the metal strut which contains nickel, chromium, manganese, titanium, molybdenum, the polymer coating and the impregnated drugs which for the first generation stents are: the antimicrotubule antineoplastic agent paclitaxel and the anti-inflammatory, immunosuppressive and antiproliferative agent sirolimus. The newer stents which are called cobalt-chromiun stents and elute the sirolimus analogs everolimus and zotarolimus both contain nickel and other metals. All these components constitute an antigenic complex inside the coronary arteries which apply chronic, continuous, repetitive and persistent inflammatory action capable to induced Kounis syndrome and stent thrombosis. Allergic inflammation goes through three phases, the early phase, the late phase and the chronic phase and these three phases correspond temporally with early (acute and sub acute), late and very late stent thrombosis. Bioabsorbable allergy free poly lactic acid self expanding stents, nickel free stainless steel materials, stent coverage with nitric oxide donors and antibodies with endothelial progenitor cell capturing abilities as well as stents eluting anti-inflammatory and anti-allergic agents might be the solution of this so feared and devastating stent complication.

Immunosuppressive therapy with oral prednisone to prevent restenosis after PCI. A multicenter randomized trial

BACKGROUND

Prednisone at immunosuppressive doses after stenting has shown remarkable efficacy in reducing ischemic recurrences in nondiabetic patients with high post-procedural levels of C-reactive protein; the study aim was to compare the clinical outcome obtained in a control group of patients treated with bare metal stents versus 2 other study groups--bare metal stent plus oral prednisone or drug eluting stents--assuming similar optimal adjunctive medical treatment.

METHODS

Five tertiary Italian hospitals enrolled 375 nondiabetic patients with coronary artery disease and no contraindications to dual antiplatelet treatment or corticosteroid therapy in a randomized, controlled study performed between 2007 and 2009. Patients were allocated into 3 study groups: bare metal stents (controls), bare metal stents followed by a 40-day prednisone treatment, or drug-eluting stents. The primary endpoint was the event-free survival of cardiovascular death, myocardial infarction, and recurrence of ischemia needing repeated target vessel revascularization at 1 year as adjudicated by an independent clinical events committee.

RESULTS

One-year follow-up was obtained in all patients. Patients receiving bare metal stents alone as compared to those treated with prednisone or drug-eluting stents had lower event-free survival; the primary endpoint was 80.8% in controls compared to 88.0% in the prednisone and 88.8% in the drug-eluting stent groups, respectively (P=.04 and .006).

CONCLUSION

Compared with bare metal stents alone, prednisone treatment after bare metal stents or drug-eluting stent implantation result in a better event-free survival at 1 year.

Time course of reendothelialization of stents in a normal coronary swine model: characterization and quantification

Late thrombosis of coronary drug-eluting stents is an infrequent but serious complication of percutaneous transluminal coronary angioplasty. The best predictor of this event is the lack of endothelialization of stent struts. The objective of this study is to characterize and quantify the time course of endothelialization of different stents implanted in nonatherosclerotic swine coronary arteries. Thirty-three Carbofilm-coated stents were implanted percutaneously in 11 anesthetized domestic, crossbred pigs (weight 25 ± 3 kg, 2 months old). Each animal received 1 stainless steel stent (SS), 1 cobalt-chromium stent (CCS), and 1 tacrolimus-eluting stent (TES) in each coronary artery. Follow-up periods were 1 day (n = 9 stents), 3 days (n = 9 stents), and 7 days (n = 15 stents). Longitudinal sections of the stented vessels were examined using scanning electron microscopy. At 1 day, there was scarce, patchy endothelialization with areas of fibrin; the endothelialization rate was similar for all the stents (SS, 29% ± 23%; CCS, 29% ± 24%; TES, 31% ± 25%; P = .9). At 3 days, there were more endothelial cells but with immature features and giant cells over fibrin; the endothelialization was greater in SS and CCS than in TES (SS, 79% ± 14%; CCS, 81% ± 17%; TES, 46% ± 9%; P = .007). At 7 days, arteries showed better endothelialization with few giant cells; the endothelialization was greater in SS and CCS than in TES (SS, 95% ± 4%; CCS, 98% ± 4%; TES, 79% ± 9%; P = .01). In conclusion, the described model is useful for the analysis of endothelialization of coronary stents and facilitates measurement of its rate of formation and characterization of the involved cell types.

Evaluation of polymer-based comparator drug-eluting stents using a rabbit model of iliac artery atherosclerosis

BACKGROUND

Although atherosclerotic models, especially in the rabbit, have existed for a long time, a comparative study of various drug-eluting stent (DES) implantations in atherosclerotic arteries have not been systematically studied.

METHODS AND RESULTS

New Zealand White rabbits (n=44) with induced atheroma received bilateral iliac artery stents: bare metal stent (BMS) (Driver) or a stent eluting zotarolimus (ZES) (Endeavor), sirolimus (SES) (Cypher), or everolimus (EES) (Xience V). After 28 days, tissues were harvested for histomorphometric analyses, en face analysis of endothelial coverage, and expression of endothelial nitric oxide synthase (eNOS). Area measurements of external elastic lamina and stent area were similar. Neointimal area was significantly less in all DES versus BMS, which was least in SES and EES; similar trends were noted for cell proliferation. Uncovered struts were greater for SES and EES and least in BMS, whereas ZES were in between and associated with the least fibrin. Macrophages of the neointima were significantly less for all DES relative to BMS. Plaque calcification underneath stents, however, was significantly greater in SES and ZES than in BMS. Although endothelial coverage in between struts was comparable between BMS and DES, there was significantly greater expression of eNOS in BMS and ZES relative to EES and SES.

CONCLUSIONS

The rabbit atherosclerotic model of stenting showed delayed healing and significantly greater reduction of neointima following implantation of SES and EES; however, delayed healing was less in ZES with greater neointima (but less than BMS), endothelial regrowth, and eNOS expression.

Essential role of ER-alpha-dependent NO production in resveratrol-mediated inhibition of restenosis

Resveratrol (Resv), a red wine polyphenol, is known to exhibit vascular protective effects and reduce vascular smooth muscle cell mitogenesis. Vascular smooth muscle cell proliferation is a critical factor in the pathogenesis of restenosis, the renarrowing of vessels that often occurs after angioplasty and/or stent implantation. Although Resv has been shown to be an estrogen receptor (ER) modulator, the role of the ER in Resv-mediated protection against restenosis has not yet been elucidated in vivo. Therefore, with the use of a mouse carotid artery injury model, our objective was to determine the role of ER in modulating Resv-mediated effects on neointimal hyperplasia. Female wild-type and ER-α(-/-) mice were administered a high-fat diet ± Resv for 2 wk. A carotid artery endothelial denudation procedure was conducted, and the mice were administered a high-fat diet ± Resv for an additional 2 wk. Resv-treated wild-type mice exhibited a dramatic decrease in restenosis, with an increased arterial nitric oxide (NO) synthase (NOS) activity and NO production. However, in the ER-α(-/-) mice, Resv failed to afford protection and failed to increase NO production, apparently because of a decreased availability of the NOS cofactor tetrahydrobiopterin. To verify the role of NO in Resv-mediated effects, mice were coadministered Resv plus a nonselective NOS inhibitor, N(G)-nitro-l-arginine methyl ester (l-NAME). Cotreatment with l-NAME significantly attenuated the antirestenotic properties of Resv. These data thus suggest that Resv inhibits vascular proliferative responses after injury, predominately through an ER-α-dependent increase in NO production.

Predictive value of C-reactive protein after drug-eluting stent implantation

During the last few decades, with the evolution of techniques and materials and the increasing experience of operators, percutaneous coronary interventions (PCI) have become an equally efficient alternative to coronary artery bypass grafts for the treatment of most coronary stenoses. Bare-metal stent implantation represented a major step forward, compared with plain old balloon angioplasty (POBA), by improving the immediate angiographic success. However, the incidence of in-stent restenosis (ISR) remained unacceptably high. Development of the drug-eluting stent (DES) significantly improved the outcome of PCI by dramatically abating the rate of ISR and reducing the incidence of target lesion revascularization. However, ISR has not been eliminated and the persistence of metal vessel scaffolding also raises concern regarding the occurrence of late or very late stent thrombosis. POBA and stent implantation have been shown to induce a local and systemic inflammatory response, whose magnitude is associated with worse clinical outcome, and they increase the risk of ISR. C-reactive protein, a marker of systemic inflammation, has been demonstrated to predict clinical and angiographic outcome after POBA or bare-metal stent implantation. However, conflicting data regarding the prognostic value of C-reactive protein following DES implantation are available. In this paper, we review the literature regarding the clinical and pathophysiological association between inflammation and prognosis after DES implantation and suggest some possible therapeutic approaches to reduce inflammatory burden with the aim to improve clinical and angiographic outcome after PCI.

Preclinical Models of Restenosis and Their Application in the Evaluation of Drug-Eluting Stent Systems

Coronary arterial disease (CAD) is the leading cause of death in the United States, the European Union, and Canada. Percutaneous coronary intervention (PCI) has revolutionized the treatment of CAD, and it is the advent of drug-eluting stent (DES) systems that has effectively allayed much of the challenge of restenosis that has plagued the success of PCI through its 30-year history. However, DES systems have not been a panacea: There yet remain the challenges associated with interventions involving bare metallic stents as well as newly arisen concerns related to the application of DES systems. To effectively address these novel and ongoing issues, animal models are relied on both to project the safety and efficacy of endovascular devices and to provide insight into the pathophysiology underlying the vascular response to injury and mechanisms of restenosis. In this review, preclinical models of restenosis are presented, and their application and limitation in the evaluation of device-based interventional technologies for the treatment of CAD are discussed.

Differential healing after sirolimus, paclitaxel, and bare metal stent placement in combination with peroxisome proliferator-activator receptor gamma agonists: requirement for mTOR/Akt2 in PPARgamma activation

RATIONALE

Sirolimus-eluting coronary stents (SESs) and paclitaxel-eluting coronary stents (PESs) are used to reduce restenosis but have different sites of action. The molecular targets of sirolimus overlap with those of the peroxisome proliferator-activated receptor (PPAR)gamma agonist rosiglitazone (RSG) but the consequence of this interaction on endothelialization is unknown.

OBJECTIVE

Using the New Zealand white rabbit iliac model of stenting, we examined the effects of RSG on SESs, PESs, and bare metal stents endothelialization.

METHODS AND RESULTS

Animals receiving SESs, PESs, or bare metal stents and either RSG (3 mg/kg per day) or placebo were euthanized at 28 days, and arteries were evaluated by scanning electron microscopy. Fourteen-day organ culture and Western blotting of iliac arteries and tissue culture experiments were conducted. Endothelialization was significantly reduced by RSG in SESs but not in PESs or bare metal stents. Organ culture revealed reduced vascular endothelial growth factor in SESs receiving RSG compared to RSG animals receiving bare metal stent or PESs. Quantitative polymerase chain reaction in human aortic endothelial cells (HAECs) revealed that sirolimus (but not paclitaxel) inhibited RSG-induced vascular endothelial growth factor transcription. Western blotting demonstrated that inhibition of molecular signaling in SES+RSG-treated arteries was similar to findings in HAECs treated with RSG and small interfering RNA to PPARgamma, suggesting that sirolimus inhibits PPARgamma. Transfection of HAECs with mTOR (mammalian target of rapamycin) short hairpin RNA and with Akt2 small interfering RNA significantly inhibited RSG-mediated transcriptional upregulation of heme oxygenase-1, a PPARgamma target gene. Chromatin immunoprecipitation assay demonstrated sirolimus interferes with binding of PPARgamma to its response elements in heme oxygenase-1 promoter.

CONCLUSIONS

mTOR/Akt2 is required for optimal PPARgamma activation. Patients who receive SESs during concomitant RSG treatment may be at risk for delayed stent healing.

Therapeutic manipulation of glucocorticoid metabolism in cardiovascular disease

The therapeutic potential for manipulation of glucocorticoid metabolism in cardiovascular disease was revolutionized by the recognition that access of glucocorticoids to their receptors is regulated in a tissue-specific manner by the isozymes of 11beta-hydroxysteroid dehydrogenase. Selective inhibitors of 11beta-hydroxysteroid dehydrogenase type 1 have been shown recently to ameliorate cardiovascular risk factors and inhibit the development of atherosclerosis. This article addresses the possibility that inhibition of 11beta-hydroxsteroid dehydrogenase type 1 activity in cells of the cardiovascular system contributes to this beneficial action. The link between glucocorticoids and cardiovascular disease is complex as glucocorticoid excess is linked with increased cardiovascular events but glucocorticoid administration can reduce atherogenesis and restenosis in animal models. There is considerable evidence that glucocorticoids can interact directly with cells of the cardiovascular system to alter their function and structure and the inflammatory response to injury. These actions may be regulated by glucocorticoid and/or mineralocorticoid receptors but are also dependent on the 11beta-hydroxysteroid dehydrogenases which may be expressed in cardiac, vascular (endothelial, smooth muscle) and inflammatory (macrophages, neutrophils) cells. The activity of 11beta-hydroxysteroid dehydrogenases in these cells is dependent upon differentiation state, the action of pro-inflammaotory cytokines and the influence of endogenous inhibitors (oxysterols, bile acids). Further investigations are required to clarify the link between glucocorticoid excess and cardiovascular events and to determine the mechanism through which glucocorticoid treatment inhibits atherosclerosis/restenosis. This will provide greater insights into the potential benefit of selective 11beta-hydroxysteroid dehydrogenase inhibitors in treatment of cardiovascular disease.

Avoiding restenosis: is there a role for glucocorticoids in the drug-eluting stent era?

Restenosis is an important limitation of percutaneous coronary interventions (PCI). In-stent restenosis is mainly due to neointimal hyperplasia, a proliferative process modulated by inflammatory mechanisms. Numerous technical and pharmacological means have been tested to reduce restenosis rates, with frequently disappointing clinical results. Drug-eluting stents (DES) have demonstrated a high efficacy in reducing restenosis, but there are some associated problems that limit its generalized utilization. Glucocorticoids (GC), as potent anti-inflammatory agents, may exert beneficial effects on neointimal proliferation. Clinical studies with oral and intracoronary GC therapy have demonstrated reduction in restenosis rates in selected patients. Although further investigations are warranted, GC might have a potential role for restenosis prevention in selected cases.

Effects of topically applied dexamethasone on mucosal wound healing using a drug-releasing stent

OBJECTIVE/HYPOTHESIS

Evaluation of the impact of continuously topically released dexamethasone using a drug-releasing stent on quality of regenerated mucosa after full thickness injury in the paranasal sinuses.

STUDY DESIGN

Prospective, controlled, randomized, double-blinded animal study.

METHODS

Nineteen New Zealand white rabbits were subjected to surgery: via an external approach, a 4 mm circular wound was created on the medial side of the maxillary sinus. The wound was covered in a randomized fashion with either a silicone foil or a new drug releasing stent system. Twelve to 30 days later, the animals were killed and histology and electron microscopy were performed. One animal was used for baseline comparisons at day 0.

RESULTS

No animals were lost due to infection or dislocation of the stent, leaving 18 animals for evaluation of postoperative healing quality. According to macroscopic examination, extent of granulations was smaller in the treatment group (dexamethasone: median 0 [95% confidence interval: 0.1-0.6]) than the silicone group (2 [1.5-2.3]; P < or = .05). Epithelial wound healing was complete in all specimens, whereas the stroma was significantly thinner in the dexamethasone-group (44 [37-60]; 178 [148-214]). Improved healing quality was achieved significantly more often on the treatment, than on the control side. Scanning electron microscopy revealed no difference between both groups.

CONCLUSIONS

Using a new drug-releasing stent system, dexamethasone efficiently decreases granulation formation and stroma thickness without impeding epithelial differentiation. Therefore, the use of this system may be of value to decrease restenosis rates in selected patients after frontal sinus surgery.

Effect of a novel drug-eluted balloon coated with genistein before stent implantation in porcine coronary arteries

BACKGROUND

The major drawback of stent implantation in native human coronary vessels is the occurrence of restenosis. Drug-eluting stents significantly reduce restenosis after percutaneous coronary intervention (PCI), but may be associated with persistent local inflammation involved in the restenosis mechanisms. In this setting coating coronary devices with anti-inflammatory agents represents an intriguing alternative to stent-based local drug delivery. The aim of the present study was to test in a porcine model the safety and efficacy of a novel Genistein-eluting balloon preceding coronary stenting.

DESIGN

Female piglets underwent PCI in a randomized fashion with either a Genistein-eluting or a standard balloon angioplasty, followed in all vessels by bare-metal stent implantation. Pigs were sacrificed at different time points to appraise safety (i.e. endothelialization) and efficacy (i.e. anti-inflammatory and anti-proliferative effects): 1, 4, and 6-8 weeks following PCI.

RESULTS

Overall analysis was conducted on 14 piglets. Twenty-five bare-metal stents were implanted preceded by angioplasty with a conventional balloon in 13 vessels and by the Genistein-eluted balloon in 12. No untoward effects were reported in either group. Healing and endothelialization appeared universal within 4 weeks. The Genistein-eluted balloon group disclosed a significant reduction, at four weeks from implantation, of the peri-stent inflammatory cells count (mononucleocytes 39 +/- 32 Vs. 96 +/- 29 per square millimetre, P = 0.019). This effect did not clearly translate into a trend towards a reduced neointimal hyperplasia at 6-8 weeks (0.13 +/- 0.11 Vs. 0.14 +/- 0.09, P = 0.835).

CONCLUSION

This study provides the first in vivo demonstration of the anti-inflammatory effects of a Genistein-eluting balloon in PCI, warranting further research including the combination of a Genistein-eluting balloon with standard drug-eluting stent.

Glucocorticoids in the prevention of restenosis after coronary angioplasty: therapeutic potential

Vessel luminal narrowing after percutaneous coronary intervention (PCI) is characterised by platelet aggregation, release of growth factors, inflammatory cell infiltration, medial smooth muscle cell (SMC) proliferation, proteoglycan deposition and extracellular matrix remodelling. It is broadly accepted that the central mechanism at the basis of the whole pathophysiological process of restenosis is inflammation, triggered by vascular injury and activated through autocrine or paracrine mediators. Glucocorticosteroids exert beneficial effects on platelet function, on SMC proliferation and on collagen synthesis as well as inflammatory cell migration and activation, thus interfering with several steps of the cascade leading to neointima formation and subsequent late lumen loss. Initial experiences with systemic administration of glucocorticoids after PCI failed to confirm the expected benefits of this treatment, probably as a result of inadequate dosage and pharmacokinetic calculations. Recently a short-term, high-dose immunosuppressive treatment scheme with oral prednisone has demonstrated remarkable clinical and angiographic results when prednisone was given orally at a dose of 1 mg/kg for 10 days, 0.5 mg/kg for 20 days and 0.25 mg/kg for 15 days. This treatment has dramatically reduced the incidence of clinical vascular events at 1 year compared with controls (relative risk 0.34; 95% CI 0.12, 0.96; p = 0.006) and reduced the incidence of angiographic restenosis below 10% in different clinical and angiographic subsets. Secondary effects of a short course of glucocorticoids are generally minor, predictable and reversible: gastric pain, water and salt retention and worsened hypertension manifest in nearly 10% of patients. The addition of diuretics and acid suppressants before discharge, and the upgrading of antihypertensive medication thereafter, if needed, are useful preventive measures to control these temporary disorders. A routine blood cell count 4 weeks after PCI is advised in patients receiving thienopyridines (clopidogrel or ticlopidine) in addition to prednisone to rule out infrequent haematological dyscrasias. Emerging evidence supports this strategy as a convenient and well tolerated alternative to more expensive and complex revascularisation procedures such as drug eluting stent (DES) implantation or cardiac surgery, provided that the treatment is reserved for carefully selected candidates, i.e. after the exclusion of those with diabetes mellitus, a recent transmural myocardial infarction, or contraindications to the administration of a short-course of high-dose glucocorticosteroids. The recent concerns regarding the long-term safety of first-generation DES and the as yet undetermined duration of dual anti-platelet treatment, further supports the need for a simple pharmacological treatment that can be applied in a large percentage of patients currently treated with PCI. Multicentre randomised studies aimed at defining the efficacy and safety of oral prednisone treatment compared with metallic stents and DES are ongoing, and will become available in upcoming years.