Histological features of restenosis associated with paclitaxel drug-coated balloon: implications for therapy.

PURPOSE: To investigate the cellular and extracellular changes induced by drug-coated balloons (DCB) in the treatment of superficial femoral artery (SFA) restenosis, and to compare histopathological features with those observed after plain old balloon angioplasty (POBA) from the same patients. METHODS AND RESULTS: Plaque samples for five patients with SFA restenosis (first-time) after POBA were collected using atherectomy and DCB. These samples constitute the POBA restenosis group. The same five patients developed recurrent restenosis (RR) after DCB, at the same intervention site. These SFA-RR lesions were again treated using atherectomy and POBA. These samples constitute the DCB restenosis group. DCB restenosis group plaques showed significant reduction in neointima, smooth muscle cells, fibroblast densities, and Ki67 index; and increase in caspase 3, features of apoptosis and type III collagen deposition in comparison to the POBA restenosis group. CONCLUSION: Plaque tissue from the DCB restenosis group show reductions in neointimal thickness, cellularity, and cellular proliferation, along with increased apoptosis, and Type III collagen content. These results suggest a different mechanistic pathway for DCB restenosis, in which neointimal proliferation is reduced but reparative fibrosis is increased. The treatment for SFA-RR after DCB may therefore benefit from different forms of therapy including scaffolding, rather than recurrent anti-proliferative therapy.

Incremental effects of diabetes mellitus and chronic kidney disease in medial arterial calcification: Synergistic pathways for peripheral artery disease progression.

Diabetes mellitus (DM) and chronic kidney disease (CKD) separately are known to facilitate the progression of medial arterial calcification (MAC) in patients with symptomatic peripheral artery disease (PAD), but their combined effect on MAC and associated mediators of calcification is not well studied. The association of MAC and calcification inducer bone morphogenetic protein (BMP-2) and inhibitor fetuin-A, with PAD, is well known. Our aim was to investigate the association of MAC with alterations in BMP-2 and fetuin-A protein expression in patients with PAD with DM and/or CKD. Peripheral artery plaques (50) collected during directional atherectomy from symptomatic patients with PAD were evaluated, grouped into no-DM/no-CKD (n = 14), DM alone (n = 10), CKD alone (n = 12), and DM+CKD (n = 14). MAC density was evaluated using hematoxylin and eosin, and alizarin red stain. Analysis of inflammation, neovascularization, BMP-2 and fetuin-A protein density was performed by immunohistochemistry. MAC density, inflammation grade and neovessel content were significantly higher in DM+CKD versus no-DM/no-CKD and CKD (p < 0.01). BMP-2 protein density was significantly higher in DM+CKD versus all other groups (p < 0.01), whereas fetuin-A protein density was significantly lower in DM+CKD versus all other groups (p < 0.001). The combined presence of DM+CKD may be associated with MAC severity in PAD plaques more so than DM or CKD alone, as illustrated in this study, where levels of calcification mediators BMP-2 and fetuin-A protein were related most robustly to DM+CKD. Further understanding of mechanisms involved in mediating calcification and their association with DM and CKD may be useful in improving management and developing therapeutic interventions.

Association of altered collagen content and lysyl oxidase expression in degenerative mitral valve disease.

BACKGROUND: Collagen cross-linking is mediated by lysyl oxidase (LOX) enzyme in the extracellular matrix (ECM) of mitral valve leaflets. Alterations in collagen content and LOX protein expression in the ECM of degenerative mitral valve may enhance leaflet expansion and disease severity. METHODS: Twenty posterior degenerative mitral valve leaflets from patients with severe mitral regurgitation were obtained at surgery. Five normal posterior mitral valve leaflets procured during autopsy served as controls. Valvular interstitial cells (VICs) density was quantified by immunohistochemistry, collagen Types I and III by picro-sirius red staining and immunohistochemistry, and proteoglycans by alcian blue staining. Protein expression of LOX and its mediator TGFß1 were quantified by immunofluorescence and gene expression by PCR. RESULTS: VIC density was increased, structural Type I collagen density was reduced, while reparative Type III collagen and proteoglycan densities were increased (P<.0001) with an increase in spongiosa layer thickness in myxomatous valves. These changes were associated with a reduction in LOX (P<.0001) and increase in TGFß1 protein expression (P<.0001). However, no significant change was seen in gene expression. Linear regression analysis identified a correlation between Type I collagen density and LOX grade (R2=0.855; P<.0001). CONCLUSIONS: Reduced Type I collagen density with a simultaneous increase in Type III collagen and proteoglycan densities possibly contributes to spongiosa layer expansion resulting in incompetent mitral valve leaflets. Observed changes in Type I and III collagen densities in Degenerative Mitral Valve Disease may be secondary to alterations in LOX protein expression, contributing to disorganization of ECM and disease severity.

An Algorithm for the Use of Embolic Protection During Atherectomy for Femoral Popliteal Lesions.

OBJECTIVES: This study sought to identify an algorithm for the use of distal embolic protection on the basis of angiographic lesion morphology and vascular anatomy for patients undergoing atherectomy for femoropopliteal lesions. BACKGROUND: Atherectomy has been shown to create more embolic debris than angioplasty alone. Distal embolic protection has been shown to be efficacious in capturing macroemboli; however, no consensus exists for the appropriate lesions to use distal embolic protection during atherectomy. METHODS: Patients with symptomatic lower extremity peripheral artery disease treated with atherectomy and distal embolic protection were evaluated to identify potential predictors of DE. Plaque collected from the SilverHawk nose cone subset was sent to pathology for analysis to evaluate the accuracy of angiography in assessing plaque morphology. RESULTS: Significant differences were found in lesion length (142.1 ± 62.98 vs. 56.91 ± 41.04; p = 0.0001), low-density lipoprotein (82.3 ± 40.3 vs. 70.9 ± 23.2; p = 0.0006), vessel runoff (1.18 ± 0.9 vs. 1.8 ± 0.9; p = 0.0001), chronic total occlusion (131 vs. 10; p = 0.001), in-stent restenosis (33 vs. 6; p = 0.0081), and calcified lesions (136 vs. 65; p < 0.001). In simple logistic regression analysis lesion length, reference vessel diameter, chronic total occlusion, runoff vessels, and in-stent restenosis were found to be strongly associated with macroemboli. Angiographic assessment of plaque morphology was accurate. Positive predictive value of 92.31, negative predictive value of 95.35, sensitivity of 92.31, and specificity of 95.35 for calcium; positive predictive value of 95.56, negative predictive value of 100, sensitivity of 100, and specificity of 92.31 for atherosclerotic plaque. Thrombus/in-stent restenosis was correctly predicted. CONCLUSIONS: Chronic total occlusion, in-stent restenosis, thrombotic, calcific lesions >40 mm, and atherosclerotic lesions >140 mm identified by peripheral angiography necessitate concomitant filter use during atherectomy to prevent embolic complications.

Intracoronary Imaging, Cholesterol Efflux, and Transcriptomes After Intensive Statin Treatment: The YELLOW II Study.

BACKGROUND: Despite extensive evidence demonstrating the beneficial effects of statins on clinical outcomes, the mechanisms underlying these effects remain elusive. OBJECTIVES: This study assessed changes in plaque morphology using intravascular imaging, with a comprehensive evaluation of cholesterol efflux capacity (CEC) and peripheral blood mononuclear cell (PBMC) transcriptomics in patients receiving high-dose statin therapy. METHODS: In a prospective study, 85 patients with stable coronary artery disease underwent percutaneous coronary intervention for a culprit lesion, followed by intracoronary multimodality imaging, including optical coherence tomography (OCT) of an obstructive nonculprit lesion. All subjects received 40 mg of rosuvastatin daily for 8 to 12 weeks, when the nonculprit lesion was reimaged and intervention performed. Blood samples were drawn at both times to assess CEC and transcriptomic profile in PBMC. RESULTS: Baseline OCT minimal fibrous cap thickness (FCT) was 100.9 ± 41.7 µm, which increased to 108.6 ± 39.6 µm at follow-up, and baseline CEC was 0.81 ± 0.14, which increased at follow-up to 0.84 ± 0.14 (p = 0.003). Thin-cap fibroatheroma prevalence decreased from 20.0% to 7.1% (p = 0.003). Changes in FCT were independently associated with CEC increase by multivariate analysis (ß: 0.30; p = 0.01). PBMC microarray analysis detected 117 genes that were differentially expressed at follow-up compared to baseline, including genes playing key roles in cholesterol synthesis (SQLE), regulation of fatty acids unsaturation (FADS1), cellular cholesterol uptake (LDLR), efflux (ABCA1 and ABCG1), and inflammation (DHCR24). Weighted coexpression network analysis revealed unique clusters of genes associated with favorable FCT and CEC changes. CONCLUSIONS: The study demonstrated an independent association between fibrous cap thickening and improved CEC that may contribute to morphological changes suggesting plaque stabilization among patients taking intensive statin therapy. Furthermore, the significant perturbations in PBMC transcriptome may help determine the beneficial effects of statin on plaque stabilization. (Reduction in Coronary Yellow Plaque, Lipids and Vascular Inflammation by Aggressive Lipid Lowering [YELLOW II]; NCT01837823).

Enhanced neointimal fibroblast, myofibroblast content and altered extracellular matrix composition: Implications in the progression of human peripheral artery restenosis.

BACKGROUND AND AIMS: Neointimal cellular proliferation of fibroblasts and myofibroblasts is documented in coronary artery restenosis, however, their role in peripheral arterial disease (PAD) restenosis remains unclear. Our aim was to investigate the role of fibroblasts, myofibroblasts, and collagens in restenotic PAD. METHODS: Nineteen PAD restenotic plaques were compared with 13 de novo plaques. Stellate cells (H&E), fibroblasts (FSP-1), myofibroblasts (α-actin/vimentin/FSP-1), cellular proliferation (Ki-67), and apoptosis (caspase-3 with poly ADP-ribose polymerase) were evaluated by immunofluorescence. Collagens were evaluated by picro-sirius red stain with polarization microscopy. Smooth muscle myosin heavy chain (SMMHC), IL-6 and TGF-ß cytokines were analyzed by immunohistochemistry. RESULTS: Restenotic plaques demonstrated increased stellate cells (2.7 ± 0.15 vs.1.3 ± 0.15) fibroblasts (2282.2 ± 85.9 vs. 906.4 ± 134.5) and myofibroblasts (18.5 ± 1.2 vs.10.6 ± 1.0) p = 0.0001 for all comparisons. In addition, fibroblast proliferation (18.4% ± 1.2 vs.10.4% ± 1.1; p = 0.04) and apoptosis (14.6% ± 1.3 vs.11.2% ± 0.6; p = 0.03) were increased in restenotic plaques. Finally, SMMHC (2.6 ± 0.12 vs.1.4 ± 0.15; p = 0.0001), type III collagen density (0.33 ± 0.06 vs. 0.17 ± 0.07; p = 0.0001), IL-6 (2.08 ± 1.7 vs.1.03 ± 2.0; p = 0.01), and TGF-ß (1.80 ± 0.27 vs. 1.11 ± 0.18; p = 0.05) were increased in restenotic plaques. CONCLUSIONS: Our study suggests proliferation and apoptosis of fibroblast and myofibroblast with associated increase in type III collagen may play a role in restenotic plaque progression. Understanding pathways involved in proliferation and apoptosis in neointimal cells, may contribute to future therapeutic interventions for the prevention of restenosis in PAD.

Relation of Internal Elastic Lamellar Layer Disruption to Neointimal Cellular Proliferation and Type III Collagen Deposition in Human Peripheral Artery Restenosis.

Smooth muscle cell proliferation and extracellular matrix formation are responsible for disease progression in de novo and restenotic atherosclerosis. Internal elastic lamella (IEL) layer maintains the structural integrity of intima, and disruption of IEL may be associated with alterations in neointima, type III collagen deposition, and lesion progression in restenosis. Nineteen restenotic plaques (12 patients) procured during peripheral interventions were compared with 13 control plaques (12 patients) without restenosis. Hematoxylin & Eosin and elastic trichrome stains were used to measure length and percentage of IEL disruption, cellularity, and inflammation score. Type I and III collagens, smooth muscle cell (smc), fibroblast density, and nuclear proliferation (Ki67) percentage were evaluated by immunohistochemistry. IEL disruption percentage (28 ± 3.6 vs 6.1 ± 2.4; p = 0.0006), type III collagen content (0.33 ± 0.06 vs 0.17 ± 0.07; p = 0.0001), smc density (2014 ± 120 vs 923 ± 150; p = 0.0001), fibroblast density (2,282 ± 297 vs 906 ± 138; p = 0.0001), and Ki67 percentage (21.6 ± 2 vs 8.2 ± 0.65; p = 0.0001) were significantly increased in restenotic plaques compared to de novo plaques. Logistic regression analysis identified significant correlation between IEL disruption and neointimal smc density (r = 0.45; p = 0.01) and with type III collagen deposition (r = 0.61; p = 0.02) in restenosis. Increased IEL disruption may trigger cellular proliferation, altering collagen production, and enhancing restenotic neointima. In conclusion, understanding the pathologic and molecular basis of restenosis and meticulous-guided interventions oriented to minimize IEL damage may aid to reduce neointimal proliferation and the occurrence of restenosis.

Histopathological Evidence of Adventitial or Medial Injury Is a Strong Predictor of Restenosis During Directional Atherectomy for Peripheral Artery Disease.

PURPOSE: To investigate the impact on restenosis rates of deep injury to the adventitial layer during directional atherectomy. METHODS: Between 2007 and 2010, 116 consecutive patients (mean age 69.6 years; 56 men) with symptomatic femoropopliteal stenoses were treated with directional atherectomy at a single center. All patients had claudication and TASC A/B lesions in the superficial femoral or popliteal arteries. Histopathology analysis of atherectomy specimens was performed to identify adventitial injury. Clinical follow-up included physical examination and duplex ultrasound scans at 3, 6, and 12 months in all patients. The primary endpoint was the duplex-documented 1-year rate of restenosis, which was determined by a peak systolic velocity ratio <2.4. Patients were dichotomized by the presence or absence of adventitial or medial cuts as evaluated by histopathology. RESULTS: Adventitial injury were identified in 62 (53%) of patients. There were no differences in baseline demographic and clinical features (p>0.05), lesion length (58.7±12.8 vs 56.2±13.6 mm, p=0.40), or vessel runoff (1.9±0.6 vs 2.0±0.6, p=0.37) between patients with and without adventitial injury, respectively. The overall 1-year incidence of restenosis was 57%, but the rate was significantly higher (p<0.0001) in patients with adventitial or medial injury (97%, 60/62) as compared with those without (11%, 6/54). CONCLUSION: Lack of adventitial injury after atherectomy for femoropopliteal stenosis is strongly related to patency at 1 year.

Expression of angiotensin-converting enzyme 2 and its end product angiotensin 1-7 is increased in diabetic atheroma: implications for inflammation and neovascularization.

AIMS: The angiotensin-converting enzyme 2 (ACE2) and its end product angiotensin 1-7 (Ang1-7) are key counterregulatory proteins to offset the deleterious effects of angiotensin II. ACE2 is decreased in diabetic kidney disease but overexpressed in metabolically active atheroma. We tested the hypothesis that ACE2 is increased in diabetic peripheral atheroma, concomitantly with Ang1-7, angiotensin II receptor 1 (AT1R), proinflammatory cytokines, macrophage infiltration, and plaque neovascularization. METHODS AND RESULTS: Peripheral atherectomy plaques collected from 12 diabetic (DM) and 12 non-DM patients were immunostained for ACE2, Ang1-7, AT1R, and proinflammatory cytokines interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α). Macrophage infiltration and neovascularization were counted using double-label immunochemistry with CD68/CD3 and CD34, respectively. Quantification was performed blindly by randomly counting positively stained cells in 20 high-power fields using previously validated methods. Tissue content of ACE2, Ang1-7, and AT1R was increased in DM when compared to non-DM (P<.0001). IL-6 and TNF-α were also increased in DM when compared to non-DM (P<.0001), as well as macrophage infiltration score and neovessel counting (P<.0001). CONCLUSION: Expression of ACE2 and its end product Ang1-7 is increased in DM atheroma, along with overexpression of AT1R, IL6, TNF-α, macrophage infiltration, and neovascularization. These results suggest that the renin-angiotensin system counterregulatory pathway may be preserved in metabolically active atheroma, offering potential targets for future therapies in diabetic atherosclerosis.

Genotype-dependent impairment of hemoglobin clearance increases oxidative and inflammatory response in human diabetic atherosclerosis.

OBJECTIVE: Haptoglobin (Hp) protein is responsible for hemoglobin clearance after intra-plaque hemorrhage. Hp gene exists as Hp-1 and Hp-2 alleles and the phenotypes show important molecular heterogeneity. We tested the hypothesis that hemoglobin clearance may be deficient in diabetic atheroma from patients with Hp2-2, triggering increased oxidative, inflammatory, and angiogenic patterns compared with controls. METHODS AND RESULTS: Forty patients with diabetes mellitus were genotyped and their peripheral plaques compared after atherectomy. Plaque hemorrhage, iron content, hemoglobin-binding protein CD163, and heme-oxygenase-1 were quantified. Oxidative, inflammatory, and angiogenic patterns were evaluated by measuring myeloperoxidase, interleukin-10, macrophages, vascular cell adhesion molecule-1, smooth muscle actin, and plaque neovascularization (CD34/CD31). Plaques with Hp2-2 (n=7) had increased hemorrhage (P<0.005), iron content (P<0.001), and reduced CD163 expression (P<0.002) compared with controls (n=14). Hp2-2 plaques had increased heme-oxygenase-1 protein (P<0.02), myeloperoxidase gene (P<0.05), and protein (P<0.0001). Anti-inflammatory interleukin-10 gene (P<0.04), and protein expressions (P<0.0001) were decreased in Hp2-2. Finally, macrophage (P<0.0001), vascular cell adhesion molecule-1 (P=0.001), smooth muscle actin (P=0.002) scores, and neovessels density (P<0.0001) were increased in Hp2-2. CONCLUSIONS: Genotype-dependent impairment of hemoglobin clearance after intra-plaque hemorrhage is associated with increased oxidative, inflammatory, and angiogenic response in human diabetic atherosclerosis.

Increased expression of oxidation-specific epitopes and apoptosis are associated with haptoglobin genotype: possible implications for plaque progression in human atherosclerosis.

OBJECTIVES: The purpose of this study was to test the hypothesis that increased oxidative stress is associated with apoptosis in human plaques with the haptoglobin (Hp) 2-2 genotype. BACKGROUND: Intraplaque hemorrhage releases free hemoglobin (Hb). Impaired Hb clearance induces oxidative stress leading to plaque progression. The binding of Hp to Hb attenuates iron-induced oxidative reactions. METHODS: Twenty-six human aortic plaques were Hp genotyped. Hp2-2 plaques (n = 13) were compared with control (Hp1-1/2-1) (n = 13). The iron grade was measured by Perl's staining. Immunostaining was used to detect oxidation-specific epitopes (OSEs) reflecting oxidized phospholipids and malondialdehyde-like epitopes. The percentages of apoptotic cells and apoptotic morphological features were quantified. DNA fragmentation and active caspase-3 were measured by in situ end-labeling and immunohistochemistry, respectively. RESULTS: In Hp2-2 plaques, iron content was increased (1.22 ± 0.15 vs. 0.54 ± 0.08; p < 0.0001) along with expression of oxidized phospholipid- (78.9 ± 5.8 vs. 38.8 ± 3.8; p < 0.0001), and malondialdehyde-like OSEs (93.9 ± 7.9 vs. 54.7 ± 3.9; p < 0.0001). The total percentages of apoptotic cells (11.9 ± 0.44 vs. 3.5 ± 0.28; p < 0.0001), nuclear fragmentation (11.8 ± 0.50 vs. 3.3 ± 0.26; p < 0.0001), nuclear condensation (10.9 ± 0.58 vs. 3.4 ± 0.20; p < 0.0001), chromatin margination (14.2 ± 0.57 vs. 6.5 ± 0.37; p < 0.0001), cytoplasmic blebs (1.6 ± 0.28 vs. 0.8 ± 0.14; p < 0.002), and eosinophilia (10.8 ± 0.74 vs. 4.2 ± 0.27; p < 0.0001) were increased in Hp2-2 plaques. Furthermore, DNA fragmentation (119.9 ± 1.40 vs. 57.5 ± 0.80; p < 0.001), and active caspase-3 density (84.7 ± 7.62 vs. 50.6 ± 7.49; p < 0.004) were increased in Hp2-2 plaques. Logistic regression analysis identified correlation between the percentage of apoptotic cells and the density of OSEs (r = 0.56; p < 0.003). CONCLUSIONS: These findings provide insights into genetic predisposition to oxidative stress and the relationship between OSEs and macrophage apoptosis that may explain advanced atherosclerosis in human Hp2-2 plaques.

Inflammation, neovascularization and intra-plaque hemorrhage are associated with increased reparative collagen content: implication for plaque progression in diabetic atherosclerosis.

Sustained inflammation may stimulate a reparative process increasing early reparative type III collagen synthesis, promoting atherosclerotic plaque progression. We evaluated inflammation, neovascularization, intra-plaque hemorrhage (IPH), and collagen deposition in human aortic atherosclerotic plaques from patients with and without diabetes mellitus (DM). Plaques were procured at autopsy from lower thoracic and abdominal aorta from DM (n = 20) and non-DM (n = 22) patients. Inflammation and neovascularization were quantified by double-label immunochemistry and the IPH grade was scored using H&E-stained sections. Type I and type III collagens were quantified using Picro-Sirius red stain with polarization microscopy and computerized planimetry. In non-DM plaques, 27%, 40%, and 33% had mild, moderate and severe inflammation in the fibrous cap and shoulder compared with 2%, 30% and 68% in DM plaques (p < 0.001). The geometric mean neovessel count was increased in DM versus non-DM plaques (140 [95% CI: 119-165] versus 59 [95% CI: 51-70]; p < 0.001). The IPH grade was increased in DM verses non-DM plaques (0.82 ± 0.11 versus 0.29 ± 0.11; p < 0.001) (percentage grade). The density of type III was increased in DM plaques (0.16 ± 0.01 versus 0.06 ± 0.01; p < 0.001) with a non-significant reduction in type I density in DM when compared with non-DM (0.28 ± 0.03 versus 0.33 ± 0.03; p = 0.303) (content per mm²). The increase in type III collagen content correlated with total neovessel content (r = 0.58; p < 0.001) in DM plaques. In conclusion, our study suggests that enhanced type III collagen deposition was associated with inflammation, neovascularization and IPH, and may be a contributing factor in DM plaque progression.

Downregulation of the hemoglobin scavenger receptor in individuals with diabetes and the Hp 2-2 genotype: implications for the response to intraplaque hemorrhage and plaque vulnerability.

In individuals with diabetes mellitus (DM), the haptoglobin (Hp) genotype is a major determinant of susceptibility to myocardial infarction. We have proposed that this is because of DM and Hp genotype-dependent differences in the response to intraplaque hemorrhage. The macrophage hemoglobin scavenging receptor CD163 plays an essential role in the clearance of hemoglobin released from lysed red blood cells after intraplaque hemorrhage. We sought to test the hypothesis that expression of CD163 is DM and Hp genotype-dependent. CD163 was quantified in plaques by immunohistochemistry, on peripheral blood monocytes (PBMs) by FACS, and as soluble CD163 (sCD163) in plasma by ELISA. In DM plaques, despite an increase in macrophage infiltration, CD163 immunoreactivity was lower, resulting in a dramatic reduction in the percentage of macrophages expressing CD163 (27+/-2% versus 70+/-2%, P=0.0001). In individuals with DM as compared with individuals without DM, the percentage of PBMs expressing CD163 was reduced (3.7+/-0.6% versus 7.1+/-0.9%, P<0.002) whereas soluble plasma CD163 was increased (2.6+/-1.1 microg/mL versus 1.6+/-0.8 microg/mL, P<0.0005). Among DM individuals, the Hp 2-2 genotype was associated with a decrease in the percentage of PBMs expressing CD163 (2.3+/-0.5% versus 5.6+/-1.3%, P=0.01) and an increase in plasma soluble CD163 (3.0+/-0.2 microg/mL versus 2.3+/-0.2 microg/mL, P=0.04). Taken together, these results demonstrate an impaired hemoglobin clearance capacity in Hp 2-2 DM individuals and may provide the key insight explaining the increased incidence of myocardial infarction in this population.