Lysed Erythrocyte Membranes Promote Vascular Calcification.

BACKGROUND: Intraplaque hemorrhage promotes atherosclerosis progression, and erythrocytes may contribute to this process. In this study we examined the effects of red blood cells on smooth muscle cell mineralization and vascular calcification and the possible mechanisms involved. METHODS: Erythrocytes were isolated from human and murine whole blood. Intact and lysed erythrocytes and their membrane fraction or specific erythrocyte components were examined in vitro using diverse calcification assays, ex vivo by using the murine aortic ring calcification model, and in vivo after murine erythrocyte membrane injection into neointimal lesions of hypercholesterolemic apolipoprotein E-deficient mice. Vascular tissues (aortic valves, atherosclerotic carotid artery specimens, abdominal aortic aneurysms) were obtained from patients undergoing surgery. RESULTS: The membrane fraction of lysed, but not intact human erythrocytes promoted mineralization of human arterial smooth muscle cells in culture, as shown by Alizarin red and van Kossa stain and increased alkaline phosphatase activity, and by increased expression of osteoblast-specific transcription factors (eg, runt-related transcription factor 2, osterix) and differentiation markers (eg, osteopontin, osteocalcin, and osterix). Erythrocyte membranes dose-dependently enhanced calcification in murine aortic rings, and extravasated CD235a-positive erythrocytes or Perl iron-positive signals colocalized with calcified areas or osteoblast-like cells in human vascular lesions. Mechanistically, the osteoinductive activity of lysed erythrocytes was localized to their membrane fraction, did not involve membrane lipids, heme, or iron, and was enhanced after removal of the nitric oxide (NO) scavenger hemoglobin. Lysed erythrocyte membranes enhanced calcification to a similar extent as the NO donor diethylenetriamine-NO, and their osteoinductive effects could be further augmented by arginase-1 inhibition (indirectly increasing NO bioavailability). However, the osteoinductive effects of erythrocyte membranes were reduced in human arterial smooth muscle cells treated with the NO scavenger 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl 3-oxide or following inhibition of NO synthase or the NO receptor soluble guanylate cyclase. Erythrocytes isolated from endothelial NO synthase-deficient mice exhibited a reduced potency to promote calcification in the aortic ring assay and after injection into murine vascular lesions. CONCLUSIONS: Our findings in cells, genetically modified mice, and human vascular specimens suggest that intraplaque hemorrhage with erythrocyte extravasation and lysis promotes osteoblastic differentiation of smooth muscle cells and vascular lesion calcification, and also support a role for erythrocyte-derived NO.

Age-Dependent and -Independent Effects of Perivascular Adipose Tissue and Its Paracrine Activities during Neointima Formation.

Cardiovascular risk factors may act by modulating the composition and function of the adventitia. Here we examine how age affects perivascular adipose tissue (PVAT) and its paracrine activities during neointima formation. Aortic tissue and PVAT or primary aortic smooth muscle cells from male C57BL/6JRj mice aged 52 weeks ("middle-aged") were compared to tissue or cells from mice aged 16 weeks ("adult"). Vascular injury was induced at the carotid artery using 10% ferric chloride. Carotid arteries from the middle-aged mice exhibited smooth muscle de-differentiation and elevated senescence marker expression, and vascular injury further aggravated media and adventitia thickening. Perivascular transplantation of PVAT had no effect on these parameters, but age-independently reduced neointima formation and lumen stenosis. Quantitative PCR analysis revealed a blunted increase in senescence-associated proinflammatory changes in perivascular tissue compared to visceral adipose tissue and higher expression of mediators attenuating neointima formation. Elevated levels of protein inhibitor of activated STAT1 (PIAS1) and lower expression of STAT1- or NFκB-regulated genes involved in adipocyte differentiation, inflammation, and apoptosis/senescence were present in mouse PVAT, whereas PIAS1 was reduced in the PVAT of patients with atherosclerotic vessel disease. Our findings suggest that age affects adipose tissue and its paracrine vascular activities in a depot-specific manner. PIAS1 may mediate the age-independent vasculoprotective effects of perivascular fat.

Revised Endografting for a Giant Descending Thoracic Aorta Aneurysm due to Synchronous Type III/Ib Endoleak, Causing Dysphagia.

BACKGROUND: Although surgical resection and graft replacement therapy for thoracic aortic aneurysms has advanced greatly over the last 20 years, significant perioperative morbidity and mortality still occur, particularly in patients considered high risk due to significant coexisting medical illness or previous operations performed for the treatment of intrathoracic disease. METHODS: The case described is that of a patient with a giant (13.8 cm) symptomatic descending thoracic aorta aneurysm (DTAA), previously treated endovascularly 15 years ago. The expanding aneurysm was due to undiagnosed synchronous type III/Ib endoleak resulting in chronic malnutrition and eventually dysphagia and dyspnea due to compressive symptoms of the esophagus. Besides the risk of rupture, dyspnea and dysphagia with progressive weight loss were significant indications necessitating repair. Regarding his major comorbidities, the patient was identified as high risk for open surgical repair, therefore an endovascular option was offered. Two valiant tube endografts were inserted and deployed successfully without complications. RESULTS: Postoperatively, upper gastrointestinal endoscopy imaging that was performed to the patient revealed marked persistent stenosis of the esophagus despite aneurysm pressure relief. However, at the multidisciplinary team meeting, an esophageal stenting was ruled out due to the risk of stent fracture and esophageal perforation with its devastating complications. Therefore, a conservative management was deemed appropriate for the patient taking into consideration the risks of prolonged hospitalization and malnourishment coupled with an unpredictable clinical course regarding the remission of the symptoms. Despite the slight gradual clinical improvement in the immediate postoperative period, the patient passed away at the 40th postoperative day due to hospital acquired pneumonia. CONCLUSIONS: Following endovascular repair of giant DTAA compressing the esophagus, significant symptomatic improvement should not be always expected due to the large residual thrombotic aneurysm sac. Although compression symptoms can be managed conservatively in patients deemed at high risk for esophageal perforation, postoperative course and management is of paramount importance and should be treated on an individual basis.

Anesthetic Management of a Parturient With Cardiac Tamponade due to Heart Perforation by an Atrial Septum Defect Repair Device: A Case Report.

With the ongoing development of safer anesthesia, pregnant women with cardiac disease are presenting more frequently for cesarean delivery. We report the successful anesthetic management of a 31-year-old parturient, on long-term anticoagulant therapy, who presented with acute cardiac tamponade due to perforation of the left atrium from a dislodged atrial septum defect occluder. The cesarean delivery was followed by temporary repair of the perforation without extracorporeal circulation (EC) due to concerns about excessive postpartum bleeding. The definitive repair of the atrial defect and the perforation were successfully accomplished under (EC) 5 days after delivery.

Down-regulation of the inhibitor of growth family member 4 (ING4) in different forms of pulmonary fibrosis.

BACKGROUND: Recent evidence has underscored the role of hypoxia and angiogenesis in the pathogenesis of idiopathic fibrotic lung disease. Inhibitor of growth family member 4 (ING4) has recently attracted much attention as a tumor suppressor gene, due to its ability to inhibit cancer cell proliferation, migration and angiogenesis. The aim of our study was to investigate the role of ING4 in the pathogenesis of pulmonary fibrosis both in the bleomycin (BLM)-model and in two different types of human pulmonary fibrosis, including idiopathic pulmonary fibrosis (IPF) and cryptogenic organizing pneumonia (COP). METHODS: Experimental model of pulmonary fibrosis was induced by a single tail vein injection of bleomycin in 6- to 8-wk-old C57BL/6mice. Tissue microarrays coupled with qRT-PCR and immunohistochemistry were applied in whole lung samples and paraffin-embedded tissue sections of 30 patients with IPF, 20 with COP and 20 control subjects. RESULTS: A gradual decline of ING4 expression in both mRNA and protein levels was reported in the BLM-model. ING4 was also found down-regulated in IPF patients compared to COP and control subjects. Immunolocalization analyses revealed increased expression in areas of normal epithelium and in alveolar epithelium surrounding Masson bodies, in COP lung, whereas showed no expression within areas of active fibrosis within IPF and COP lung. In addition, ING4 expression levels were negatively correlated with pulmonary function parameters in IPF patients. CONCLUSION: Our data suggest a potential role for ING4 in lung fibrogenesis. ING4 down-regulation may facilitate aberrant vascular remodelling and fibroblast proliferation and migration leading to progressive disease.

A rare case of late right ventricular perforation by a passive-fixation permanent pacemaker lead.

The present paper is an interesting and rare complication of implantation of a permanent pacemaker lead. The rarity of the case is based upon that ventricular perforation is usually present during implantation, whereas in our case, it was presented late--1 month after implantation. Furthermore, in our case, the pacemaker lead had migrated through the left hemidiaphragm into the peritoneal cavity.

Association study of the CTH 1364 G>T polymorphism with coronary artery disease in the Greek population.

Background Cystathionine γ-lyase enzyme, which is encoded by the CTH gene, is responsible for hydrogen sulfide (H2S) production in the endothelium. The CTH 1364 G>T polymorphism may alter the CTH expression and H2S bioavailability, thus leading to atherosclerosis and coronary artery disease (CAD). We examined the potential association of the CTH 1364 G>T polymorphism with CAD. Methods The CTH 1364 G>T polymorphism was determined in 178 coronary artery bypass grafting (CABG) patients and 156 non-atherosclerotic controls of Greek Caucasian origin using the PCR-RFLP method. Results No significant difference in the frequency of the CTH 1364 G>T genotypes (p = 0.281) and alleles (p = 0.265) was found between the CABG patients and controls. After conducting stratification according to sex, analysis showed a numerical difference in the CTH 1364 TT genotype frequency in female participants that did not reach statistical significance (16.3% and 8.5% in the CABG and controls, respectively, p = 0.26). The frequency of the CTH 1364 TT genotype between the male CABG patients and controls did not differ (p = 0.507). Conclusions The CTH 1364 G>T polymorphism was not associated with CAD in the studied population. However, interestingly, a higher - if not significantly so - CTH 1364 TT genotype frequency was present in female CABG patients compared with female controls. Larger studies are necessary to conclude on the potential overall or gender-driven association between CTH 1364 G>T gene polymorphism and CAD.

Increased Lymphangiogenesis and Lymphangiogenic Growth Factor Expression in Perivascular Adipose Tissue of Patients with Coronary Artery Disease.

Experimental and human autopsy studies have associated adventitial lymphangiogenesis with atherosclerosis. An analysis of perivascular lymphangiogenesis in patients with coronary artery disease is lacking. Here, we examined lymphangiogenesis and its potential regulators in perivascular adipose tissue (PVAT) surrounding the heart (C-PVAT) and compared it with PVAT of the internal mammary artery (IMA-PVAT). Forty-six patients undergoing coronary artery bypass graft surgery were included. Perioperatively collected C-PVAT and IMA-PVAT were analyzed using histology, immunohistochemistry, real time PCR, and PVAT-conditioned medium using cytokine arrays. C-PVAT exhibited increased PECAM-1 (platelet endothelial cell adhesion molecule 1)-positive vessel density. The number of lymphatic vessels expressing lymphatic vessel endothelial hyaluronan receptor-1 or podoplanin was also elevated in C-PVAT and associated with higher inflammatory cell numbers, increased intercellular adhesion molecule 1 (ICAM1) expression, and fibrosis. Significantly higher expression of regulators of lymphangiogenesis such as vascular endothelial growth factor (VEGF)-C, VEGF-D, and VEGF receptor-3 was observed in C-PVAT compared to IMA-PVAT. Cytokine arrays identified angiopoietin-2 as more highly expressed in C-PVAT vs. IMA-PVAT. Findings were confirmed histologically and at the mRNA level. Stimulation of human lymphatic endothelial cells with recombinant angiopoietin-2 in combination with VEGF-C enhanced sprout formation. Our study shows that PVAT surrounding atherosclerotic arteries exhibits more extensive lymphangiogenesis, inflammation, and fibrosis compared to PVAT surrounding a non-diseased vessel, possibly due to local angiopoietin-2, VEGF-C, and VEGF-D overexpression.

Epigenetics-by-Sex Interaction for Coronary Artery Disease Risk Conferred by the Cystathionine γ-Lyase Gene Promoter Methylation.

Coronary artery disease (CAD) is a major global health burden whereby gene-by-environment-by-sex interactions play an important role. Coronary artery bypass graft (CABG) surgery involves patients with well-documented and severe CAD. Hence, the study of CAD in a context of the CABG surgery serves as an advantageous model for disease phenotype ascertainment and genetic association studies. We report here new observations from a case-control genetic association study on promoter methylation of the cystathionine γ-lyase (CTH) gene and its association with CAD. To the best of our knowledge, this is the first clinical study to show the DNA methylation status of the CTH promoter in relation to this clinical phenotype. CTH encodes for the hydrogen sulfide generating enzyme named CSE in the endothelium that is mechanistically highly relevant for CAD. In a sample of 334 subjects from Greece (178 cases with CAD and who underwent CABG, and 156 controls), CTH promoter methylation was analyzed using a SYBR Green-based quantitative methylation-specific polymerase chain reaction. We found increased methylation in CTH promoter in cases (19.1%) compared to controls (10.3%) (p = 0.024). Gene-by-sex analysis sustained the significant association in men (p = 0.032) but not in women (p = 0.884). By using multivariate analyses after controlling for potential confounders such as smoking, age, and gender, we found that increased CTH gene promoter methylation was associated with CAD in the total sample (odds ratio [OR] = 2.163, 95% confidence interval [CI] 1.038-4.506, p = 0.039) and in men (OR = 2.418, 95% CI 1.048-5.581, p = 0.039) but not in women (OR = 0.542, 95% CI 0.094-3.140, p = 0.495). These observations collectively warrant further precision medicine and biomarker research to examine the CTH methylation status as a putative epigenetic regulator of CAD risk in larger and independent samples.

Differences between perivascular adipose tissue surrounding the heart and the internal mammary artery: possible role for the leptin-inflammation-fibrosis-hypoxia axis.

AIM: The factors mediating the paracrine effects of perivascular adipose tissue (PVAT) in atherosclerosis are largely unknown. The adipokine leptin has been implicated in the increased cardiovascular risk in obesity and may locally promote neointima formation independently of circulating leptin levels. In patients with established coronary artery disease, we examined the expression of leptin as well as of its possible inducers in 'cardiac' PVAT surrounding the aortic root and coronary arteries (C-PVAT), and compared it to the PVAT surrounding the internal mammary artery (IMA-PVAT), a vessel resistant to atherosclerosis. METHODS AND RESULTS: Tissue specimens collected from male patients undergoing coronary artery bypass surgery were processed for real-time PCR, ELISA, in situ hybridization, and immunohistochemistry analysis. Leptin protein expression was elevated in C-PVAT compared to IMA-PVAT, independent of serum leptin levels. Compared to IMA-PVAT, C-PVAT exhibited more pronounced angiogenesis and inflammation, as indicated by significantly higher numbers of PECAM1-positive vessels and CD68-positive macrophages, and was characterized by a greater extent of fibrosis and hypoxia. Increased expression of hypoxia-inducible factor-1α and Fos-like antigen (FOSL)2, factors known to enhance leptin gene transcription, was observed in C-PVAT. As a proof of concept, exposure of human adipocytes to chemical hypoxia resulted in significantly increased FOSL2 and leptin mRNA levels. CONCLUSIONS: A higher degree of local tissue hypoxia and up-regulation of leptin expression in the perivascular adipose tissue, along with increased vascularization, inflammation, and fibrosis, may contribute to the increased atherosclerotic plaque burden in the coronary arteries compared to the IMA.

Diltiazem versus amiodarone to prevent atrial fibrillation in coronary surgery.

The prophylactic effect of amiodarone on atrial fibrillation after coronary bypass grafting with extracorporeal circulation was compared with that of diltiazem in two groups of 60 patients each. Patients were monitored continuously for 8 days. The incidence of atrial fibrillation was recorded retrospectively in a control group of 60 patients who received our standard prophylactic regimen of an oral beta blocker. The incidence of postoperative atrial fibrillation was not significantly different in the two test groups: 11.7% for the amiodarone group and 10% for the diltiazem group. The incidence of atrial fibrillation in the control group was 23.3% and the differences were marginally significant when compared to the amiodarone ( p = 0.093) and diltiazem groups ( p = 0.050). The prophylactic use of diltiazem or amiodarone is feasible and safe for patients undergoing coronary bypass, with similar rates of atrial fibrillation.