The multiple roles of chemokines in the mechanisms of stent biocompatibility.

While the advent of drug-eluting stents has been clinically effective in substantially reducing the rates of major stent-related adverse events compared with bare metal stents, vascular biological problems such as neointimal hyperplasia, delayed re-endothelialization, late stent thrombosis are not eliminated and, increasingly, neoatherosclerosis is the underlying mechanism for very late stent failure. Further understanding regarding the mechanisms underlying the biological responses to stent deployment is therefore required so that new and improved therapies can be developed. This review will discuss the accumulating evidence that the chemokines, small inflammatory proteins, play a role in each key biological process of stent biocompatibility. It will address the chemokine system in its specialized roles in regulating the multiple facets of vascular biocompatibility including neointimal hyperplasia, endothelial progenitor cell (EPC) mobilization and re-endothelialization after vascular injury, platelet activation and thrombosis, as well as neoatherosclerosis. The evidence in this review suggests that chemokine-targeting strategies may be effective in controlling the pathobiological processes that lead to stent failure. Preclinical studies provide evidence that inhibition of specific chemokines and/or broad-spectrum inhibition of the CC-chemokine class prevents neointimal hyperplasia, reduces thrombosis and suppresses the development of neoatherosclerosis. In contrast, however, to these apparent deleterious effects of chemokines on stent biocompatibility, the CXC chemokine, CXCL12, is essential for the mobilization and recruitment of EPCs that make important contributions to re-endothelialization post-stent deployment. This suggests that future chemokine inhibition strategies would need to be correctly targeted so that all key stent biocompatibility areas could be addressed, without compromising important adaptive biological responses.

Neutrophil-to-lymphocyte ratio and platelet-to-lymphocyte ratio: novel markers for the diagnosis and prognosis in patients with restenosis following CAS.

Aim: In this study, we investigated the effect of neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio on restenosis status in patients undergoing carotid angioplasty stenting (CAS). Methodology & results: Clinical imageology and receiver operating characteristic analysis were utilized to study the prognostic significance of NLRs/platelet-to-lymphocyte ratios and their correlation with survival. NLR of restenosis (+) patients was evidently increased after the CAS procedures, while the NLR of restenosis (-) patients before the CAS procedures being the lowest. Area under the curve of pre-CAS NLR or/and post-CAS NLR were all evidently higher than 50%. Also, restenosis incidence was the highest in patients with both high pre-CAS and high post-CAS values. Conclusion: Therefore, NLR can be utilized as an independent prognostic indicator to predict the incidence of restenosis after CAS procedures.

Nanoparticles responsive to the inflammatory microenvironment for targeted treatment of arterial restenosis.

Coronary arterial disease (CAD) remains the leading cause of death globally. Percutaneous coronary interventions are frequently used nonsurgical techniques for treating CAD, which may unfortunately lead to arterial restenosis. Currently, there are no effective drugs that can thoroughly prevent restenosis. We hypothesize inflammation-triggerable nanomedicines may function as effective therapeutics for targeted therapy of restenosis, by preferentially releasing their payload at the diseased site. To demonstrate our hypothesis and develop targeted nanotherapies for restenosis, this study was designed to examine effectiveness of nanomedicines responsive to the inflammatory microenvironment with mild acidity and high reactive oxygen species (ROS). To this end, an acetalated ß-cyclodextrin (ß-CD) material (Ac-bCD) was synthesized as a pH-responsive carrier material, while a ROS-responsive material (Ox-bCD) was produced by hydrophobic functionalization of ß-CD with an oxidation-labile group. Based on these two responsive materials, either pH- or ROS-responsive nanoparticles (NPs) were produced by a nanoprecipitation technique and fully characterized. Using rapamycin (RAP) as a candidate drug, responsive nanotherapies were fabricated. In vitro hydrolysis and release studies confirmed these nanovehicles and nanotherapies exhibited desirable responsive behaviors. Both in vitro cell culture and in vivo evaluations revealed their good safety profile. These responsive NPs could be effectively internalized by rat vascular smooth muscle cells, which in turn notably potentiated anti-proliferation and anti-migration activities of RAP. After intravenous (i.v.) injection, NPs may be accumulated at the injured site in the carotid artery of rats subjected to balloon angioplasty injury. Compared with a non-responsive nanotherapy based on poly(lactide-co-glycolide), treatment with either pH- or ROS-responsive nanotherapy by i.v. injection more effectively attenuated neointimal hyperplasia in a rat model of arterial restenosis. Accordingly, nanotherapeutics responsive to the inflammatory microenvironment hold great potential for the management of vascular restenosis by selectively releasing drug molecules at the inflamed sites.

[Coronary Artery Bypass Grafting for In-stent Restenosis Probably Caused by Allergic Response;Report of a Case].

A 58-year-old female presented to our hospital with recurrence of chest pain. She had undergone coronary intervention using biolimus-eluting-stent for total occlusion of the left anterior descending artery(LAD) 3 years before. Since then in-stent restenosis had repeated 4 times in 3 years. In the interim, another everolimus-eluting-stent had been placed on the same lesion. The contact metal allergic patch test revealed the existence of allergic response to nickel and cobalt which were the structural components of these stents. She underwent off-pump coronary artery bypass grafting, and these stents were removed. The invasions of macrophages and eosinophils around the stent-s were pathologically proven. One year after surgery she is doing well without angina or allergic symptom. These observations suggested the allergic reaction of the coronary artery against the stents.

Cu-bearing steel reduce inflammation after stent implantation.

Copper (Cu)-bearing stainless steel with release of Cu2+ ions is a novel material for coronary stents that could reduce the in-stent restenosis after the stent implantation. The inflammation has been recently recognized as an important factor to smooth muscle cells proliferation, thrombosis, and hence the restenosis post-angioplasty. The objective of this study is to further investigate the effect and relevant mechanism of Cu-bearing stainless steel (316L-Cu SS) on the inflammation reaction after stent implantation. The results demonstrated that, compared with commercial coronary stent material (316L SS), 316L-Cu SS could inhibit the inflammation caused by endothelial dysfunction through blockading the inflammatory factors (TNF-α, IL-1ß, 6, 8), which would then reduce the recruitment and infiltration of leukocytes, rather than have direct effect on leukocytes. This finding further explained the reduction effect of 316L-Cu SS on in-stent restenosis from a novel view.

Agonistic autoantibodies against the angiotensin AT1 receptor increase in unstable angina patients after stent implantation.

OBJECTIVES: Agonistic AT1 receptor autoantibodies have been described in patients with hypertension and preeclampsia. These autoantibodies could stimulate proliferation of vascular smooth muscle cells (VSMCs), which are involved in angiotensin II-induced vascular injury in cardiovascular disease. Hence, in this study, we explored the existence of agonistic AT1 receptor autoantibodies in unstable angina (UA) patients and the possible effects of them on the in-stent restenosis of these patients. METHODS: A total of 95 UA patients and 98 healthy volunteers were enrolled. The serum of each patient was analyzed for the presence of AT1 receptor autoantibodies by enzyme-linked immunosorbent assay. Their effects on VSMC proliferation and c-fos and c-jun expression were studied in vitro. RESULTS: AT1 receptor autoantibodies were detected in 34/95 patients with UA. The incidence was 10.2% in the control group and rose to 47.37% after stent implantation. In vitro, this autoantibody had agonist-like activity, shown as stimulation of VSMC proliferation and upregulation of c-fos and c-jun expression. These effects were similar to that of angiotensin II and could be weakened partly by the AT1-receptor blocker valsartan. CONCLUSION: Our findings show that the autoantibody from UA patients has similar agonistic activity to angiotensin II and might play a role in the pathogenesis of in-stent restenosis in these patients.

Levels of circulating CD34+/KDR+ cells do not predict coronary in-stent restenosis.

BACKGROUND: Angiographic and clinical parameters are poor predictors of in-stent restenosis. Bone marrow-derived CD34(+) cells that coexpress a receptor for vascular endothelial growth factor (kinase insert domain receptor [KDR]) are committed to endothelial lineage. Mobilization and infusion of CD34(+)/KDR(+) cells accelerates re-endothelialization and reduces neointimal thickness in vascular injury models. Bioengineered stents capturing CD34(+) cells also show expedited re-endothelialization. We examined whether circulating CD34(+)/KDR(+) cell counts can be used to predict restenosis in a bare-metal stent (BMS). METHODS: CD34(+)/KDR(+) cells were counted by flow cytometry in 124 nondiabetic patients before BMS implantation and the relation to in-stent late luminal loss (LLL) was examined by angiography at 6 months (primary end point). Neointima was also quantified as the maximum percentage area stenosis (M%AS) and percentage volume intima hyperplasia (%VIH) on intravascular ultrasonography (secondary end points). RESULTS: Multiple linear regression analysis, taking into account implanted stent length and diameter, revealed no relation between CD34(+)/KDR(+) cell counts and LLL (partial regression coefficient b = 0.11; 95% confidence interval [CI], -0.19-0.42; P = 0.46). Similarly, no relation between CD34(+)/KDR(+) cell counts and M%AS or %VIH could be demonstrated. Moreover, the increase in CD34(+)/KDR(+) cell counts over 6 months was unrelated to LLL (b = -0.15; 95% CI, -0.42-0.12; P = 0.28), M%AS, and %VIH. CONCLUSIONS: Although our study does not exclude a pathophysiologic role for CD34(+)/KDR(+) cells in the formation of neointima, cell counts before percutaneous coronary intervention proved to be unrelated to LLL or intravascular ultrasonographically derived restenosis parameters in coronary BMSs at 6 months.

Late-phase inflammatory response as a feature of in-stent restenosis after drug-eluting stent implantation.

OBJECTIVES: The aim of this study was to compare pathological features among in-stent restenosis lesions after drug-eluting stent (DES) placement, those after bare metal stent (BMS) placement, and de-novo atherosclerotic lesions. BACKGROUND: Restenosis after stenting is an over-reaction of the wound-healing response after vascular injury, which is characterized by a sequence of inflammation, granulation, extracellular matrix remodeling, and smooth muscle cell proliferation and migration. Recent advances in DES technology could considerably succeed in inhibiting this sequence of events. Thus, we hypothesized that the mechanism of in-stent restenosis after DES stenting might be different from that after BMS stenting as well as atherosclerosis. METHODS: Tissues obtained by directional atherectomy (DES: seven specimens, BMS: 17 specimens, and de-novo: 15 specimens) were immunostained for T lymphocytes (CD45), macrophages (CD68), smooth muscle cells (α-smooth muscle actin), endothelial cells (von Willebrand factor), and activated platelets (P-selectin). RESULTS: The accumulation of T lymphocytes tended to increase and that of macrophages increased significantly in the DES lesions compared with BMS lesions. No significant differences were observed for the other parameters evaluated. CONCLUSION: Pathological features of restenotic tissues after DES implantation showed a stronger inflammatory response compared with those after BMS implantation. Thus, the mechanism of restenosis after DES implantation may be different from that observed after BMS implantation.

Comparison of inflammatory response after implantation of sirolimus- and paclitaxel-eluting stents in patients on hemodialysis.

Because systemic inflammation after coronary intervention places patients at increased risk of subsequent cardiac events, we aimed to compare clinical outcomes and chronic serum inflammation markers of paclitaxel-eluting stents (PES) and sirolimus-eluting stents (SES) in hemodialysis patients. Paclitaxel-eluting stents and SES were implanted in 36 patients with 46 lesions, and 32 patients with 40 lesions, respectively. In addition to 1-year major adverse cardiac event (MACE) rates, high-sensitivity C-reactive protein (hs-CRP), interleukin-6 (IL-6), neopterin, intercellular adhesion molecule 1 (ICAM-1) and vascular cell adhesion molecule 1 (VCAM-1) were also compared before and 9 months after percutaneous coronary intervention (PCI). The incidence of MACE was significantly lower in the PES group than in the SES group (11.1 vs. 25.0 %, respectively, P = 0.042), mainly due to the reduction of target lesion revascularization in the PES group (6.5 vs. 17.5 %, P = 0.003). The logarithm of hs-CRP as well as IL-6 decreased significantly 9 months post-PCI compared with pre-PCI in the PES group (hs-CRP: 3.65 ± 0.35 vs. 2.91 ± 0.48, P = 0.007; IL-6: 6.73 ± 3.66 vs. 2.61 ± 2.29, P = 0.017) but not in the SES group (hs-CRP: 3.33 ± 0.29 vs. 3.42 ± 0.27, P not significant; IL-6: 6.08 ± 4.97 vs. 5.66 ± 4.29, P not significant). However, neopterin, ICAM-1, and VCAM-1 remained unchanged both pre-PCI and 9 months post-PCI in both groups. Moreover, MACE were less frequent in patients with decreased hs-CRP levels 9 months post-PCI compared with patients without decreased hs-CRP levels (P = 0.002) in all patients. Paclitaxel-eluting stents appear to be more effective than SES in reducing MACE rates, especially target lesion revascularization, and may be able to stabilize local inflammatory changes of target lesions specifically in patients on hemodialysis. Thus PES, which inhibit in-stent restenosis and cardiac events in hemodialysis patients, may play an important role in suppression of chronic inflammatory response in target lesions as compared with SES. Chronic continuous inflammation plays an important role after implantation of both types of stent with regard to in-stent restenosis in patients on hemodialysis.

CD40 ligand: a neo-inflammatory molecule in vascular diseases.

CD40 Ligand (CD40L), a member of the TNF family, was initially thought to be solely implicated in thymus-dependent humoral responses. However, work by several groups showed that CD40L plays a more global role in various systems. Recent evidence has outlined an important role for CD40L in the physiopathology of the vascular system. Indeed, by interacting with its principal receptor, CD40, or with the recently identified receptors, namely αIIbß3, α5ß1, and Mac-1 integrins, CD40L displayed many biological functions in different types of vascular cells. In addition, the CD40L system was demonstrated a major player in the pathology of vascular diseases, such as atherosclerosis and restenosis. This review outlines the expression pattern and the functional properties of CD40L and its receptors at different cellular levels in the vascular system. In addition, we thoroughly describe evidence showing the implication of CD40L interactions in atherosclerosis, restenosis, and their associated clinical complications.

Liposomal alendronate for the treatment of restenosis.

The current treatment for coronary restenosis following balloon angioplasty involves the use of a mechanical or drug eluting stent (DES). The advent of DES systems has effectively allayed much of the challenge of restenosis that has plagued the success of percutaneous coronary interventions (PCI). However, there are certain limitations to DES use, among which is late stent thrombosis. Innate immunity and inflammation are of major importance in the overreaction of the wound healing response to PCI-induced vascular injury, which leads to restenosis. Liposomes containing alendronate have been shown to deplete circulating monocytes and reduce experimental restenosis. This review presents a unique systemic approach for treating restenosis with alendronate liposomal nano-carriers and reports on its formulation development, formulation variables affecting monocyte/macrophage targeting, pharmacokinetics (PK) and biodistribution, in vitro and in vivo anti-inflammatory effect, and the recent results of the phase II clinical trial.

The union of anti-CD34 antibody can improve the performance of drug-eluting stents.

OBJECTIVES: The authors investigate whether the combination of anti-CD34 antibody with DES is win-win cooperation. BACKGROUND: DES may reduce the risk of restenosis compared to bare-metal stents (BMS), but they were found to inhibit the healing process of intima. METHODS: Fifteen BMS, 17 DES, and 16 combined anti-CD34 antibody and DES were randomly implanted in the coronary arteries of 22 minipigs. Ten minipigs were followed up to 2 weeks. The stenting coronary segments were examined by histological examination and scanning electron microscopy after in vivo coronary angiography and intracoronary optical coherence tomography (OCT) examinations. The other 12 minipigs were followed up to 3 months. Coronary angiography and intracoronary OCT examination were performed in vivo and histological examination was performed on the stenting coronary segments. RESULTS: After 2 weeks, the neointimal covering level of the DES was lower than that in BMS, but the covering level of the combined stents was even better than the BMS. After 3 months, neointimal hyperplasia was significant in the BMS, but not in the other two types of stents. The in-stent late lumen loss of the combined stents even showed a decreasing tendency when compared with the DES. CONCLUSION: The combination of anti-CD34 antibody and DES can not only well offset the short-term inhibitory effect on re-endothelialization but also slightly enhance the long-term antiproliferative effect.

Comparison of inflammatory markers for the prediction of neointimal hyperplasia after drug-eluting stent implantation.

BACKGROUND: We compared the relationship between inflammatory markers and neointimal hyperplasia (NIH) after drug-eluting stent (DES) implantation. METHODS: We implanted a single DES in 42 consecutive patients with stable angina. The plasma high-sensitivity C-reactive protein (hs-CRP), interleukin-6 (IL-6), and matrix metalloproteinase-9 (MMP-9) levels were measured before, and 24 and 72 h after the procedure. Angiography and intravascular ultrasound were performed. RESULTS: No relationship was noted between the baseline hs-CRP level and NIH. A significant positive correlation was noted between NIH and the hs-CRP level obtained at 24 h (r=0.435, P=0.004), and 72 h (r=0.334, P=0.031) after the procedure. Interestingly, there was a positive correlation between the change (Δ) in the hs-CRP level and NIH at 24 h (r=0.414, P=0.006). The fourth quartile of the hs-CRP at 24 h after percutaneous coronary intervention (PCI) had significantly larger volume of NIH than the first quartile (20.1±25.1 vs. 2.7±6.4 mm, P<0.05). Moreover, NIH in the fourth quartile (20.9±26.4 mm) was higher than the first quartile (3.3±8.6 mm) of the Δ hs-CRP level at 24 h (P<0.05) after the procedure. Although the IL-6 level at the baseline and 72 h after the procedure were positively correlated with NIH (r=0.337, P=0.029 and r=0.435, P=0.004, respectively), the Δ IL-6 level at any stage was not correlated with NIH. Neither the MMP-9 level nor the Δ MMP-9 level at any stage was correlated with NIH. CONCLUSION: This prospective intravascular ultrasound study showed the inflammatory response after PCI, as measured by hs-CRP levels, but not the baseline hs-CRP level, predict NIH after DES implantation. Neither a change in the IL-6 nor MMP-9 levels at any stage after PCI reflected NIH.

The predictive value of inflammatory activity and markers of the adipo-insular axis on restenosis in patients with type 2 diabetes.

AIMS: Patients with type 2 diabetes (T2DM) have a high restenosis rate after percutaneous coronary intervention (PCI). This study investigated whether markers of inflammation and the adipo-insular axis associated with T2DM and poor metabolic control were able to predict restenosis after PCI in T2DM patients. METHODS AND RESULTS: The predictive value of traditional and non-traditional risk markers, including IL-1ß, IL-6, TNF-α, hsCRP, interferon gamma, leptin, IGF-I, insulin, proinsulin and NT-proBNP, was investigated in 82 patients with T2DM. A re-angiography 6 months after the index percutaneous coronary intervention (PCI) revealed that 43% of the patients had a restenosis. In a multiple regression analysis, the only independent predictors of restenosis were fasting glucose before the PCI and previous myocardial infarction (odds ratio [OR] 1.44, 95% confidence interval [CI] 1.07-1.92; p = 0.015 and OR 8.00, 95% CI 2.49-25.67; p ≤ 0.001, respectively). None of the other markers remained as significant predictors. CONCLUSION: Fasting glucose prior to the PCI was an independent predictor of restenosis in patients with T2DM while analyses of a variety of markers related to inflammation and the adipo-insular axis did not add any further information.

Physicochemical parameters affecting liposomal bisphosphonates bioactivity for restenosis therapy: internalization, cell inhibition, activation of cytokines and complement, and mechanism of cell death.

Partial inactivation and transient depletion of monocytes/macrophages by liposomal bisphosphonates (LIP-BPs) is widely experimented in various inflammatory disorders including restenosis. Previous studies on activation of cytokines by LIP-BPs are limited to certain cell lines. Moreover, the correlation between in vitro and in vivo studies and complement (C) activation has not been reported. We report here a comprehensive study on the bioactivity of LIP-BPs on various cells' internalization and proliferation, mechanism of cell death, cytokines (in vitro and in vivo) and C activation (in the rat, rabbit and pig). The role of the following parameters has been determined i) drug type (clodronate/alendronate); ii) vesicles size (60-800nm); iii) charge (neutral/negative/ positive); and iv) cell culture type (various cell lines and primary cultures). It was found that monocyte/macrophage inhibition and cytokine activation depend on the cell type, with a limited correlation to the bioactivity obtained in the rat and rabbit models of restenosis. Negatively charged liposomes (85+/-20nm) effectively depleted rabbit's monocytes (67% depletion), with a minor activation of cytokines and no C activation. It is concluded that cell culture studies are insufficient for assessing cytokine activation, and that by controlling LIP-BP properties (size, charge and drug type) optimal bioactivity could be achieved.

[Effect of the anti-inflammatory peptide preparation ingramon on the blood levels of acute-phase proteins and chemokines in patients after coronary stenting].

AIM: To study the effect of the anti-inflammatory peptide preparation ingramon on the peripheral blood levels of inflammatory markers in patients with exercise-induced stable angina after coronary stenting (CS). SUBJECTS AND METHODS: The investigation enrolled 64 patients with stable angina who had undergone coronary bypass surgery, of them 34 patients received ingramon in addition to standard therapy. The blood levels of high-sensitive C-reactive protein (hs-CRP), fibrinogen, the chemokines MCP-1, IL-8, IP-10, and MID were measured before and 1, 2, and 7 days and 1, 3, and 6 months after surgery. Twenty patients who had gone coronarography (CG) only were examined as a control group. RESULTS: In the post CS patients receiving only standard therapy, the levels of hs-CRP and fibrinogen were much higher on days 1, 2, and 7 after surgery than in the CG patients. On day 1 following CS, the increment in hs-CRP correlated with the length of implanted stents. During ingramon therapy, the content of hs-CRP and fibrinogen was considerably lower on days 1, 2, and 7 after CS than in the control group; this trend persisted a month after surgery; there was also a reduction in MCP-1 levels within the first 24 hours after initiation of therapy. The levels of the chemokines IP-10, MIG, and IL-8 were significantly unchanged. CONCLUSION. When added to standard therapy, ingramon exerts a positive effect against risk factors for coronary heart disease (CHD) and its events. Further investigations are required to define the impact of ingramon therapy on prognosis in patients with CHD.

Prognostic values of C-reactive protein levels on clinical outcome after implantation of sirolimus-eluting stents in patients on hemodialysis.

BACKGROUND: Percutaneous coronary intervention (PCI) using drug-eluting stents significantly reduces the risk of restenosis in the general population. However, in patients on hemodialysis, adverse cardiac events are frequently seen even if treated with drug-eluting stents. Recent studies suggest that C-reactive protein (CRP) reflects vascular wall inflammation and can predict adverse cardiac events. We evaluated possible prognostic values of CRP on outcomes in patients on hemodialysis undergoing PCI with drug-eluting stents. METHODS AND RESULTS: A total of 167 patients undergoing PCI with sirolimus-eluting stents for stable angina (322 lesions) were enrolled. They were divided into tertiles according to serum CRP levels. We analyzed the incidence of major adverse cardiovascular events including cardiovascular death, nonfatal myocardial infarction, and target lesion revascularization after PCI as well as quantitative coronary angiographic data. The mean follow-up was 31 months (SD, 14). Major adverse cardiac events occurred in 11 patients (19.6%) of the lowest tertile, in 22 patients (39.3%) of the middle tertile, and in 28 patients (50.9%) of the highest tertile during follow-up period (P=0.0009). There was a progressive increase in neointimal growth after sirolimus-eluting stent implantation during follow-up because preprocedural CRP levels were higher, despite similar angiographic data just after PCI. Angiographic restenosis at 6 to 8 months after PCI was seen in 10.6% in the lowest tertile, 17.9% in the middle tertile, and 32.0% in the highest tertile (P=0.0007). CONCLUSIONS: Increased preprocedural serum CRP levels would predict higher major adverse cardiac events and restenosis rates after sirolimus-eluting stents implantation in patients on hemodialysis.