Elevated plasma levels of factor VIII enhance arterial thrombus formation on erosive smooth muscle cell-rich neointima but not normal intima in rabbits.

BACKGROUND: Plaque erosion, a type of coronary atherothrombosis, involves superficial injury to smooth muscle cell (SMC)-rich plaques. Elevated levels of coagulation factor VIII (FVIII) correlate with an increased ischemic heart disease risk. FVIII may contribute to thrombus formation on eroded plaques. AIMS: We aimed to elucidate the role of elevated FVIII in arterial thrombus formation within SMC-rich neointima in rabbits. METHODS AND RESULTS: We assessed the effect of recombinant human FVIII (rFVIII) on blood coagulation in vitro and platelet aggregation ex vivo. An SMC-rich neointima was induced through balloon injury to the unilateral femoral artery. Three weeks after the first balloon injury, superficial erosive injury and thrombus formation were initiated with a second balloon injury of the bilateral femoral arteries 45 min after the administration of rFVIII (100 IU/kg) or saline. The thrombus area and contents were histologically measured 15 min after the second balloon injury. rFVIII administration reduced the activated partial thromboplastin time and augmented botrocetin-induced, but not collagen- or adenosine 5'-diphosphate-induced, platelet aggregation. While rFVIII did not influence platelet-thrombus formation in normal intima, it increased thrombus formation on SMC-rich neointima post-superficial erosive injury. Enhanced immunopositivity for glycoprotein IIb/IIIa and fibrin was observed in rFVIII-administered SMC-rich neointima. Neutrophil count in the arterial thrombus on the SMC-rich neointima correlated positively with thrombus size in the control group, unlike the rFVIII group. CONCLUSIONS: Increased FVIII contributes to thrombus propagation within erosive SMC-rich neointima, highlighting FVIII's potential role in plaque erosion-related atherothrombosis.

BMP-4 impedes endothelial cell migration in neointimal hyperplasia via FoXO-3 specific modulation of reactive oxygen species.

BACKGROUND AND AIMS: Endothelial cell injury causes vascular barrier dysfunction and leukocyte recruitment to the underlying tissue. Bone morphogenetic protein 4 (BMP-4) is a transforming growth factor that exerts pro-inflammatory effects on the endothelium. Here, we investigated the effects of BMP-4 on endothelial cell (EC) migration following balloon injury in SD rats. METHODS: An intimal hyperplasia model was established using balloon injury. Hematoxylin-eosin staining (HE) and silver staining were used to detect the alteration of endothelial cells recovery after balloon injury. Serum BMP-4 levels were assessed by ELISA. Human umbilical vein endothelial cells (HUVECs) were cultured. MTT assay was used to measure cell viability. Protein expression was detected by Western blot. Intracellular reactive oxygen species (ROS) was detected by dichloro-dihydro-fluorescein diacetate (DCFH-DA). HUVECs migration was measured via transwell assay and scratch wound assay. RESULTS: The results indicated that BMP-4 inhibition significantly decreased total plasma activity of BMP-4 and reduced neointimal hyperplasia by stimulating endothelial cell migration, but did not affect the medial area following balloon injury. BMP-4 suppressed the formation of ROS via forkhead box O3 (FoXO-3)/superoxide dismutase 1 (SOD-1). In vitro, a high level of ROS induced by BMP-4 impeded HUVECs migration. CONCLUSIONS: The results suggest that BMP-4 inhibition is a potential means of preventing intimal hyperplasia formation after balloon injury.

Hypoxia-inducible factors in arteriovenous fistula maturation: A prospective cohort study.

BACKGROUND: Neointimal hyperplasia is the main cause of arteriovenous fistula (AVF) failure. Hypoxia-inducible factors (HIFs) factors are associated with neointimal hyperplasia. Thus, we investigated the association between HIF-2 alpha (HIF-2α) and AVF maturation in end-stage kidney disease (ESKD) patients. METHODS: This prospective cohort study was conducted in 21 voluntary healthy subjects and 50 patients with ESKD who were eligible for AVF creation. Inclusion criteria were being ESKD patients without a history of AVF surgery and dialysis. Eight patients excluded from the study due to having unavailable veins six patients were excluded due to acute thrombosis after surgery. One patient lost to follow-up. A total of 35 patients were included in final analysis. The blood samples were collected a day before the AVF surgery for biochemical parameters and HIF-2α measurement. HIF-2α levels were measured by the ELISA method. RESULTS: Compared with healthy subjects, ESKD patients had a significantly higher level of HIF-2α. [1.3 (1.0-1.9) vs 2.2 (1.6-3.0)] (P = .002). Patients were divided into two groups after the evaluation of AVF maturation, as the mature group (n = 19) and the failure group (n = 16). Serum HIF-2α level was 1.7 (1.1-1.8) in the mature group; however, it was 3.1 (2.8-3.3 in failure group (P < .001). Multiple logistic regression analyses showed that HIF-2α independently predicted AVF maturation. The ROC curve analysis showed that HIF-2α > 2.65 predicted AVF maturation failure with the 87% sensitivity and 94% specificity [AUC:0.947, 95% CI (0.815-0.994), P < .001]. CONCLUSIONS: HIF-2-α levels were higher in ESKD patients than healthy subjects. HIF-2-α could be a marker of AVF maturation failure.

Osteoprotegerin promotes intimal hyperplasia and contributes to in-stent restenosis: Role of an αVß3/FAK dependent YAP pathway.

OBJECTIVE: Abnormal proliferation and migration of vascular smooth muscle cells (VSMCs) are related to in-stent-restenosis (ISR) following percutaneous coronary intervention (PCI). Osteoprotegerin (OPG) has been implicated in various vascular diseases. However, the effects of OPG on ISR and the underlying mechanism remained elusive. We here investigated the association between OPG and ISR, and to demonstrate the role and potential mechanisms of OPG in neointimal hyperplasia. APPROACH AND RESULTS: From 2962 patients who received coronary angiography and follow-up coronary angiography at approximately one year, 291 patients were diagnosed with ISR, and another 291 gender- and age- matched patients without ISR were selected as controls. Serum OPG levels were significantly increased in patients with ISR. Multivariable logistic regression analysis indicated that OPG level was independently associated with the increased risk of ISR. In a mouse femoral artery wire injury model, upregulated OPG was evidenced in vascular tissue after injury. OPG deletion attenuated the vascular injury-induced neointimal hyperplasia and related gene expression in mice. OPG promoted neointimal hyperplasia and human aortic smooth muscle cell (hASMC) proliferation and migration through activation of yes-associated protein (YAP), a major downstream effector of the Hippo signaling pathway, whereas knockdown or inhibition of YAP in hASMCs blunted OPG-induced above effects. Moreover, we found that OPG, as a ligand for integrin αVß3, mediated phosphorylation of focal adhesion kinase (FAK) and actin cytoskeleton reorganization, resulting in YAP dephosphorylation in hASMCs. OPG-dependent YAP and VSMC activation was prevented by treatment with αVß3-blocking antibodies and inhibitors of FAK and actin stress fibers. CONCLUSIONS: Increased serum OPG levels are associated with increased risk of ISR following PCI and OPG could promote neointimal hyperplasia in response to injury through integrin αVß3 mediated FAK and YAP activation, indicating OPG/YAP inhibition might serve as an attractive novel target for the prevention of ISR after PCI.

Fimasartan reduces neointimal formation and inflammation after carotid arterial injury in apolipoprotein E knockout mice.

BACKGROUND: The beneficial effects of angiotensin II type 1 receptor blockers (ARBs) on atherosclerosis have been demonstrated in numerous studies. We investigated the effects of fimasartan on reducing neointimal formation and systemic inflammation after carotid artery (CA) injury in Apolipoprotein E knockout (ApoE KO) mice. METHODS: ApoE KO mice were randomly allocated to Group I (without CA injury), Group II (without CA injury + Fimasartan), Group III (CA injury), and Group IV (CA injury + Fimasartan). Fimasartan was orally administered everyday starting 3 days before iatrogenic left CA injury. RESULTS: At 28 days, neointimal hyperplasia and the inflammatory cytokines including TNFα, IL-6, ICAM, and MMP-9 in the peripheral blood were significantly reduced in Groups II and IV compared to Groups I and III, respectively. All fimasartan-administered groups revealed significant increases of CD4+CD25+Foxp3+ regulatory T (Treg) cells with increased plasma levels of IL-10 and TGFß. In addition, increased CD8+ T cells by fimasartan were correlated with reduced smooth muscle cell (SMC) proliferation in the neointima in Groups II and IV. Furthermore, the populations of Treg and CD8+ T cells in total splenocytes were increased in Groups II and IV compared to Groups I and III, respectively. The enlargement of spleens due to CA injury in the Group III was attenuated by fimasartan, as shown in the Group IV. These data indicate that fimasartan significantly reduced SMC proliferation in neointima and increased Treg cells in ApoE KO CA injury mice. CONCLUSIONS: This study suggests fimasartan could be an efficient strategy for reduction of atherosclerotic progression, with a decrease in immune response and systemic inflammation.

Involvement of stromal cell-derived factor-1α (SDF-1α), stem cell factor (SCF), fractalkine (FKN) and VEGF in TSG protection against intimal hyperplasia in rat balloon injury.

BACKGROUND: Intimal hyperplasia is the major therapeutic concern after percutaneous coronary intervention. The aim of this study is to investigate effects of 2,3,4',5-tetrahydroxystilbene-2-O-ß-D glucoside (TSG) on intimal hyperplasia and the underling mechanisms through attenuating the expressions of stromal cell-derived factor-1α (SDF-1α)/CXCR4, stem cell factor (SCF)/c-kit and fractalkine (FKN)/CX3CR1, and through promoting re-endothelialization with vascular endothelial growth factor (VEGF). METHOD: Rats were operated with carotid artery balloon injury. The treatment groups were gavaged with 50 and 100 mg/kg/d of TSG. After 10 days of treatment, carotid artery pathological changes were evaluated by histology. Serum levels of SDF-1α, SCF, FKN and VEGF were detected by enzyme linked immunosorbent assay. The protein expressions of the receptors c-kit, CXCR4, CX3CR1, as well as CD34 and proliferating cell nuclear antigen (PCNA) were detected by immunochemistry. RESULTS: TSG dose-dependently inhibited balloon injury-induced intimal hyperplasia, as evidenced by reducing neointima area (NIA), neointima area/media area (NIA/MA), neointima area/internal elastic area (NIA/IELA), and by decreasing the protein expression of PCNA. TSG reduced serum levels of SDF-1α, SCF and FKN, and it also decreased the expressions of the corresponding receptors c-kit, CXCR4, CX3CR1 in neointima. Importantly, the level of VEGF in peripheral blood and the expression of CD34 in vascular walls were increased to promote re-endothelialization. CONCLUSIONS: This study clearly demonstrated that TSG was effective in inhibiting intimal hyperplasia, and this effect was mediated, at least in part, through the SCF/c-kit, SDF-1α/CXCR4 and FKN/CX3CR1 axes. Importantly, TSG could increase VEGF and CD34 to promote endothelial repair.

Upregulated 14­3­3ß aggravates restenosis by promoting cell migration following vascular injury in diabetic rats with elevated levels of free fatty acids.

Mono­unsaturated free fatty acids (FFAs) can serve as a predictive indicator of vascular restenosis following interventional therapy, particularly in individuals with high­fat diet­induced type 2 diabetes. However, the pathogenic mechanism remains to be fully elucidated. In the present study, the levels of tyrosine 3­monooxygenase/tryptophan 5­monooxygenase activation protein ß (YWHAB; also known as 14­3­3ß), in vascular smooth muscle cells (VSMCs) treated with different concentrations of oleic acid (OA) were examined by reverse transcription­quantitative polymerase chain reaction and western blot analyses. The migration of VSMCs was examined using wound­healing and Transwell migration assays. The protein distribution of B­cell lymphoma 2 (BCL­2)­associated death promoter (BAD) in VSMCs treated with OA was examined by immunofluorescence and western blot analyses. In in vivo experiments, the carotid artery morphology of rats in different groups was assessed at 14 days post­injury by non-invasive ultrasonographic imaging and confirmed by histological staining. The expression of YWHAB was upregulated by OA in a concentration­dependent manner in VSMCs. In the in vivo experiments, carotid stenosis was more serious among high­FFA diabetic rats. However, silencing of YWHAB significantly alleviated carotid neointimal hyperplasia among the diabetic rats with elevated FFA levels. In addition, YWHAB silencing alleviated the migration of OA­treated VSMCs and increased translocation of the BAD protein from the cytoplasm to the mitochondria. In conclusion, the results showed that FFA­induced upregulation of YWHAB was involved in neointimal hyperplasia by enhancing the migration of VSMCs following carotid artery injury. The inhibition of YWHAB may serve as a novel potential pharmacological target for preventing vascular restenosis following interventional therapy in diabetic individuals with high FFA levels.

Inhibition of intimal hyperplasia in murine aortic allografts by administration of a small-molecule TLR4 inhibitor TAK-242.

Graft arteriosclerosis (GA) is the leading cause of late cardiac allograft dysfunction. The innate immune system plays a major role in GA, paprticularly Toll-like receptor 4 (TLR4) signaling. Here we characterized the role of TLR4 and its antagonist TAK-242 in a mouse model of GA. BALB/c (H-2d) donor aortas were transplanted into C57BL/6 (H-2b) recipients, and the mice received intraperitoneal injection of 3 or 10 mg/kg of TAK-242 or vehicle every other day for 1, 2, 4, 6, 8 and 12 weeks. With TAK-242 administration, intimal hyperplasia initially appeared at 2 weeks after transplantation, and TAK-242 postponed the progression of neointimal formation in allogeneic aortic grafts. TAK-242 treatment reduced CD68+ macrophage accumulation in the allografts, reduced the levels of ly-6Chi monocytes in peripheral blood, bone marrow and spleen, and downregulated proinflammatory cytokine and chemokine levels. Ex vivo we observed that TAK-242 could improve the graft microenvironment by interfering the Tck/Mφ IL12p70 and IFNγ axis, reducing CCL2-mediated migration of vascular smooth cells.

Ozonetherapy protects from in-stent coronary neointimal proliferation. Role of redoxins.

BACKGROUND: In-stent restenosis and poor re-endothelization usually follow percutaneous transluminal coronary angioplasty, even using drug-eluting stents, due to inflammation and oxidative stress. Medical ozone has antioxidant and anti-inflammatory properties and has not been evaluated in this context. OBJECTIVES: To evaluate whether ozonotherapy might reduce restenosis following bare metal stents implantation in relation to the redoxin system in pigs. METHODS: Twelve male Landrace pigs (51±9kg) underwent percutaneous transluminal circumflex coronary arteries bare metal stent implantation under heparine infusion and fluoroscopical guidance, using standard techniques. Pigs were randomized to ozonetherapy (n=6) or placebo (n=6) treatment. Before stenting (24h) and twice a week for 30days post-stenting, venous blood was collected, ozonized and reinfused. Same procedure was performed in placebo group except for ozonation. Both groups received antiplatelet treatment. Histopathology and immunohistochemistry studies were performed. RESULTS: Severe inflammatory reaction and restenosis with increase in the immunohistochemical expression of thioredoxin-1 were observed in placebo group 30days after surgery. Oppositely, ozonetherapy drastically reduced inflammatory reaction and restenosis, and showed no increase in the Trx-1 immunohistochemical expression 30days after surgery. Immunolabeling for Prx-2 was negative in both groups. Ozonated autohemotherapy strikingly reduced restenosis 30days following PTCA with BMS implantation in pigs. CONCLUSIONS: Stimulation of the redoxin system by ozone pretreatment might neutralize oxidative damage from the start and increase antioxidative buffering capacity post-injury, reducing further damage and so the demand for antioxidant enzymes. Our interpretation agrees with the ozone oxidative preconditioning mechanism, extensively investigated.

Comparison of Chronic Angioscopic Findings of Bare Metal Stents, 1st-Generation Drug-Eluting Stents and 2nd-Generation Drug-Eluting Stents　- Multicenter Study of Intra-Coronary Angioscopy After Stent (MICASA).

BACKGROUND: No previous study has reported a comprehensive comparison of the chronic angioscopic findings after bare metal stent (BMS), and 1st- and 2nd-generation drug-eluting stents (DES). METHODS AND RESULTS: The Multicenter Study on Intra-Coronary Angioscopy after Stent (MICASA) is a multicenter registry of coronary angioscopy. A total of 264 stents were observed by coronary angioscopy 1 year after PCI. There were 15 BMS, 90 1st-generation DES, and 159 2nd-generation DES. Neointimal coverage (NC) of the stent was classified into 4 grades from 0 (no coverage) to 3 (complete coverage). Yellow color (YC) of plaque at the stented segment was graded from 0 (white) to 3 (bright yellow). Minimum (Min-) and Maximum (Max-) NC grade were significantly lower with 1st- and 2nd-generation DES than with BMS. Although the Max-NC grade was similar, the Min-NC grade was significantly higher for 2nd-generation DES than for 1st-generation DES. Both the YC grade and the incidence of thrombus with 2nd-generation DES were lower than with the 1st-generation DES and were comparable to BMS. Multivariate analysis showed that low-density lipoprotein, 1st-generation DES, and acute coronary syndrome were independent factors for yellow plaque (YG2 or 3), and that hypertension and 1st-generation DES were independent factors for the incidence of thrombus. CONCLUSIONS: Coronary angioscopy revealed more homogeneous coverage with white neointima and less thrombus after 2nd-generation DES as compared with 1st-generation DES. These findings may explain the favorable clinical outcomes observed for patients treated with 2nd-generation DES. (Circ J 2016; 80: 1916-1921).

Factor VII-activating protease deficiency promotes neointima formation by enhancing leukocyte accumulation.

Essentials Factor VII-activating protease (FSAP) is a plasma protease involved in vascular processes. Neointima formation was investigated after vascular injury in FSAP-/- mice. The neointimal lesion size and the accumulation of macrophages were increased in FSAP-/- mice. This was due to an increased activity of the chemokine (C-C motif) ligand 2 (CCL2). SUMMARY: Background Factor VII-activating protease (FSAP) is a multifunctional circulating plasma serine protease involved in thrombosis and vascular remodeling processes. The Marburg I single-nucleotide polymorphism (MI-SNP) in the FSAP-coding gene is characterized by low proteolytic activity, and is associated with increased rates of stroke and carotid stenosis in humans. Objectives To determine whether neointima formation after vascular injury is increased in FSAP-/- mice. Methods and Results The neointimal lesion size and the proliferation of vascular smooth muscle cells (VSMCs) were significantly enhanced in FSAP-/- mice as compared with C57BL/6 control mice after wire-induced injury of the femoral artery. Accumulation of leukocytes and macrophages was increased within the lesions of FSAP-/- mice at day 3 and day 14. Quantitative zymography demonstrated enhanced activity of gelatinases/matrix metalloproteinase (MMP)-2 and MMP-9 within the neointimal lesions of FSAP-/- mice, and immunohistochemistry showed particular costaining of MMP-9 with accumulating leukocytes. Using intravital microscopy, we observed that FSAP deficiency promoted the intravascular adherence and the subsequent transmigration of leukocytes in vivo in response to chemokine ligand 2 (CCL2). CCL2 expression was increased in FSAP-/- monocytes but not in the vessel wall. There was no difference in the expression of platelet-derived growth factor (PDGF-BB). Conclusions FSAP deficiency causes an increase in CCL2 expression and CCL2-mediated infiltration of leukocytes into the injured vessel, thereby promoting SMC proliferation and migration by the activation of leukocyte-derived gelatinases. These results provide a possible explanation for the observed association of the loss-of-function MI-SNP with vascular proliferative diseases.

Reverse apolipoprotein A-I mimetic peptide R-D4F inhibits neointimal formation following carotid artery ligation in mice.

The ApoA-I mimetic peptide D-4F has demonstrated potent atheroprotective actions in vivo and in vitro. We investigated the effect of R-D4F (ie, the D-4F peptide with reverse order of amino acids) on intimal hyperplasia after vascular injury in a mouse model of carotid artery ligation. Adult male C57BL/6J mice were pretreated intraperitoneally with vehicle, D-4F (1 mg/kg), or R-D4F (1 mg/kg or 5 mg/kg) daily for 3 days; the mice were then subjected to left carotid artery ligation. All treatments were continued for 28 days after surgery. Neither D-4F nor R-D4F treatment affected serum lipid levels. Morphometric analysis showed that the occluded vessels had significant neointimal formation, compared with the uninjured arteries in vehicle-treated mice. Like the D-4F treatment, R-D4F treatment significantly (P < 0.05) inhibited intimal hyperplasia (-42%), local neutrophil and macrophage infiltration, and mRNA expression of the proinflammatory mediator monocyte chemotactic protein 1 (-55%) and vascular cell adhesion protein 1 (-53%), compared with vehicle. Furthermore, the vasoprotective effect of high-dose R-D4F was significantly enhanced, compared with the low dose. In cultured mouse RAW 264.7 macrophages, pretreatment with R-D4F also effectively inhibited lipopolysaccharide-induced leukocyte integrin CD11b expression, a key molecule for leukocyte infiltration. Taken together, these results suggest that R-D4F has significant anti-inflammatory features and facilitates prevention of neointimal formation after vascular injury in mice.

Decreased expression of vitamin D receptors in neointimal lesions following coronary artery angioplasty in atherosclerotic swine.

BACKGROUND: Inflammatory cytokines, such as TNF-α, play a key role in the pathogenesis of occlusive vascular diseases. Activation of vitamin D receptors (VDR) elicits both growth-inhibitory and anti-inflammatory effects. Here, we investigated the expression of TNF-α and VDR in post-angioplasty coronary artery neointimal lesions of hypercholesterolemic swine and examined the effect of vitamin D deficiency on the development of coronary restenosis. We also examined the effect of calcitriol on cell proliferation and effect of TNF-α on VDR activity and expression in porcine coronary artery smooth muscle cells (PCASMCs) in-vitro. METHODOLOGY/PRINCIPAL FINDINGS: Expression of VDR and TNF-α and the effect of vitamin D deficiency in post-angioplasty coronary arteries were analyzed by immunohistochemistry and histomorphometry. Cell proliferation was examined by thymidine and BrdU incorporation assays in cultured PCASMCs. Effect of TNF-α-stimulation on the activity and expression of VDR was analyzed by luciferase assay, immunoblotting and immunocytochemistry. In-vivo, morphometric analysis of the tissues revealed typical lesions with significant neointimal proliferation. Histological evaluation showed expression of smooth muscle α-actin and significantly increased expression of TNF-α in neointimal lesions. Interestingly, there was significantly decreased expression of VDR in PCASMCs of neointimal region compared to normal media. Indeed, post-balloon angioplasty restenosis was significantly higher in vitamin D-deficient hypercholesterolemic swine compared to vitamin D-sufficient group. In-vitro, calcitriol inhibited both serum- and PDGF-BB-induced proliferation in PCASMCs and TNF-α-stimulation significantly decreased the expression and activity of VDR in PCASMCs. CONCLUSIONS/SIGNIFICANCE: These data suggest that significant downregulation of VDR in proliferating smooth muscle cells in neointimal lesions could be due to atherogenic cytokines, including TNF-α. Vitamin D deficiency potentiates the development of coronary restenosis. Calcitriol has anti-proliferative properties in PCASMCs and these actions are mediated through VDR. This could be a potential mechanism for uncontrolled growth of neointimal cells in injured arteries leading to restenosis.