Coronary stent migration to aorta with successful recovery during aortobifemoral bypass

We present with full and proper consent of the patient, the case of a 64-year-old man with severe peripheral arterial disease and a known chronic infrarenal aortic occlusion causing severe short-distance claudication. Preoperative computed tomography angiography was significant for a new "cylindrical" calcified lesion. During the elective surgery, the lesion was confirmed to be a coronary stent. The coronary stent was confirmed to be from the patient's prior percutaneous coronary intervention to the left anterior descending artery 1 year prior. The stent was removed without complications by the surgical team. To the best of our knowledge, this is the first such case to be described in current literature. This patient is currently alive, and a revision of his left anterior descending artery intervention was found to be unwarranted on repeat coronary angiography.

Outcome of rectus femoris muscle flaps performed by vascular surgeons for the management of complex groin wounds after femoral artery reconstructions

OBJECTIVE

Groin wound complications after femoral artery reconstructions are highly morbid and notoriously difficult to treat. Successful techniques include long-term antibiotic therapy, operative débridement, and muscle flap coverage. Historically, more complex muscle flap coverage, such as a rectus femoris muscle flap (RFF), has been performed by plastic and reconstructive surgeons. In this study, the experience of vascular surgeons performing RFF in the management of wound complications after femoral artery reconstructions is reported.

METHODS

Clinical data between 2012 and 2018 were retrospectively analyzed. Data were summarized, and standard statistical analysis was performed.

RESULTS

There were 23 patients who underwent 24 RFFs for coverage of complex groin wounds after femoral artery reconstructions. One of the 23 patients underwent bilateral RFFs. In this study cohort, patients had a median age of 67.5 years, and 79% (n = 19) were male. Median body mass index was 28.0 kg/m², and 38% of patients were classified as obese on the basis of body mass index criteria. A history of tobacco use was present in 88%; however, only 29% were current smokers. Diabetes was present in 38% of patients and chronic kidney disease in 29%. Of the 24 RFFs, 14 (58%) were constructed in patients with reoperative groin surgery resulting in the need for muscle flap coverage. Femoral endarterectomy was the most common index procedure (46%), followed by infrainguinal leg bypass surgery (17%) and aortobifemoral bypass (17%). Grafts used during the original reconstruction included 12 bovine pericardial patches (50%), 6 Dacron grafts (25%), 4 PTFE grafts (17%), and 2 autogenous reconstructions (8%). Microbiology data identified 33% of patients (n = 8) to have gram-positive bacterial infections alone, 21% (n = 5) to have gram-negative infections alone, and 29% (n = 7) to have polymicrobial infections; 4 patients (13%) had negative intraoperative culture data. Median hospital stay after RFF was 8 days, and median follow-up time was 29.3 months. Major amputation was avoided in 20 of 24 limbs (83%) undergoing RFF. Eight patients underwent intentional graft or patch explantation (33%) before RFF, whereas 14 of the remaining 15 patients (93%) had successful salvage of the graft or patch after RFF. Two of the patients (13%) who underwent RFF with the intention of salvaging a prosthetic graft or patch required later graft excision. After RFF, 30-day and 1-year survival was 96% and 87%, respectively.

CONCLUSIONS

RFF coverage of complex groin wounds after femoral artery reconstructions may safely be performed by vascular surgeons with excellent outcomes.

Outcomes of familial abdominal aortic aneurysm repair in the Vascular Quality Initiative

OBJECTIVE

Recent investigations have reported increased rates of aneurysm-related complications after endovascular aneurysm repair (EVAR) in familial abdominal aortic aneurysm (fAAA) patients. The purpose of this study was to evaluate the outcomes of open aortic repair (OAR) and EVAR in sporadic AAA (spAAA) and fAAA patients in the Society for Vascular Surgery Vascular Quality Initiative.

METHODS

This was a retrospective review of all AAA repairs in the Vascular Quality Initiative from 2003 to 2017. Patients' data were summarized, and standard statistical analysis was performed. Patients with known genetic syndromes and centers with long-term follow-up of <50% of patients were excluded.

RESULTS

From 2003 to 2017, there were 1997 fAAA patients compared with 18,185 spAAA patients undergoing OAR and EVAR during the same study period. Compared with their spAAA counterparts, fAAA patients were younger (P < .001), were more likely to be living at home before surgery (P = .008), and demonstrated a lower incidence of coronary artery disease (P = .001) and hypertension (P = .039). Rates of smoking and end-stage renal disease did not differ between groups. However, fAAA patients were more likely to have aneurysmal degeneration of their iliac arteries (P < .001) and to undergo OAR (P < .001). When analyzing patients undergoing OAR, we found that fAAA patients were more likely to require concomitant renal bypass surgery (P = .012) but were extubated sooner (P = .005), received fewer blood transfusions (P < .001), and had a shorter length of stay (P = .018). Although individual complication rates did not differ between fAAA and spAAA groups after OAR, a composite end point of all early postoperative complications was decreased in fAAA patients (P = .020). When comparing fAAA and spAAA patients who underwent EVAR, we found a greater incidence of early lumbar branch endoleaks (type II) in fAAA patients; however, the rate of proximal type IA endoleaks (P = .279) and the rate of late reintervention for sac growth (P = .786), any endoleak (P = .439), or rupture (P = .649) did not differ between the groups. Whereas spAAA patients undergoing EVAR required longer postoperative intensive care unit stays (P < .001) and had a greater incidence of blood transfusions (P < .001), fAAA and spAAA patients had similar rates of postoperative complications (P = .510), 30-day mortality (P = .177), and long-term mortality (P = .259).

CONCLUSIONS

This study shows that patients with a familial form of AAA do not have increased morbidity or mortality after AAA repair. Our findings suggest that EVAR and OAR are both safe and effective for fAAA patients. Further studies with longer follow-up are needed to best care for this unique cohort of patients.

Adductor canal compression syndrome in an 18-year-old female patient leading to acute critical limb ischemia: A case report

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Adductor canal compression syndrome is an unusual cause of limb ischemia.

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Adductor canal compression syndrome typically occurs in young, physically fit adults.

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Knowledge of rare disorders is crucial when treating young patients for limb ischemia.

Background

Adductor canal compression syndrome is a rare non-atherosclerotic cause of arterial occlusion and limb ischemia.

Presentation of case

The patient is an 18-year-old healthy female who presented to the emergency department with acute left lower extremity ischemia. Her symptoms began as sudden onset mild foot pain approximately two months ago. Over the 72 h prior to presentation, she developed severe pain, pallor, paralysis, loss of pedal pulses, paresthesia, and poikilothermia. Due to her advanced ischemia, she was taken immediately to the operating room for angiography and intervention. Initial angiography demonstrated distal superficial femoral and popliteal artery occlusions along with lack of tibial or pedal artery blood flow. She underwent percutaneous mechanical thrombectomy and initiation of catheter directed thrombolysis. After 48 h of catheter directed thrombolysis and repeat mechanical thrombectomy, computed tomography (CT) was performed and demonstrated external compression of the superficial femoral artery in the adductor canal and residual chronic thrombus. Echocardiography and CT of the thoracic aorta was also performed, and were negative, therefore excluding other potential sources of arterial embolism. She next underwent surgical exploration, division of an anomalous musculotendinous band compressing the left superficial femoral artery and thromboendarterectomy of the distal left superficial femoral artery. The patient recovered well without any post-operative complications and could return to her daily activities 3 weeks following surgery.

Conclusion

Knowledge of rare non-atherosclerotic vascular disorders, such as adductor canal compression syndrome, is paramount when treating patients who present with limb ischemia and lack traditional risk factors.

Endovascular retrieval of an irrigation cannula from the thoracic aorta following cardiac surgery: A case report

INTRODUCTION

Endovascular techniques to retrieve intravascular foreign bodies are a necessary component of the Vascular surgeon's skill set. We report the successful retrieval of an embolized irrigation cannula from the thoracic aorta following aortic valve replacement.

PRESENTATION OF CASE

The patient is an 81 year old male who underwent coronary artery bypass grafting and aortic valve replacement. Prior to closure, the aortotomy was irrigated with heparinized saline using a syringe with an olive tip irrigation cannula. When the syringe was handed back to the nursing staff, the tip was noted to be missing but could not be found. Prior to closure of the sternum, the field was searched again for the tip and thus the chest was closed. The missing instrument then prompted an intraoperative chest radiograph that demonstrated a metal irrigation cannula superimposed on the cardiac silhouette. Additionally, a transesophageal echocardiogram was performed, which demonstrated the irrigation cannula within the descending thoracic aorta. Right common femoral artery was accessed and a thoracic aortogram was performed demonstrating the cannula to be lodged in the descending thoracic aorta. Intravascular ultrasound (IVUS) was performed to exclude an aortic abnormality preventing the caudad migration of the cannula. No aortic pathology was identified. A tri-lobed snare was used to grasp the cannula at its tip and withdrawn into the right external iliac artery. The cannula was successfully removed through a transverse arteriotomy in the distal right external iliac artery. The patient's postoperative course was uneventful.

CONCLUSION

Endovascular retrieval of intravascular foreign bodies is minimally invasive, relatively simple, and carries minimal morbidity compared to conventional open surgical techniques. This unusual case demonstrates the importance of a working knowledge of techniques and instruments requisite for retrieval of intravascular foreign bodies.

Patients with familial abdominal aortic aneurysms are at increased risk for endoleak and secondary intervention following elective endovascular aneurysm repair

OBJECTIVE

A recent investigation has documented an increased risk of aneurysm-related complications after endovascular aneurysm repair (EVAR) of familial abdominal aortic aneurysms (fAAAs). We hypothesized that fAAA patients are not at increased risk for complications following open AAA repair or EVAR when compared with sporadic abdominal aortic aneurysm (spAAA) patients. To this end, we performed a single institution retrospective review.

METHODS

Epidemiologic data were collected through the electronic medical record. Family history data were obtained from a questionnaire administered at the initial vascular surgery consultation. Major adverse events were defined as myocardial infarction, respiratory failure, renal failure, bowel ischemia, limb ischemia, multisystem organ failure, intracranial hemorrhage, paraplegia, hemorrhage, or death. Endoleaks were classified in accordance with the standardized reporting practices of the Society for Vascular Surgery. AAA-related complications were defined as the need for a secondary intervention due to endoleak, limb ischemia, or postimplantation rupture.

RESULTS

A total of 392 patients with complete clinical data underwent elective AAA repair from 2004 to 2014. Of these 392 patients, 89 (23%) were classified as fAAA patients and 303 (77%) were classified as spAAA patients. With the exception of increased rates of chronic obstructive pulmonary disease (P = .0009) and pack-years smoked (P = .03) in spAAA patients, demographics did not differ. Sixty-two percent (n = 55) of fAAA patients and 68% (n = 205) of spAAA patients underwent EVAR (P = .30). fAAA patients did not incur any significant difference in major adverse events following open AAA repair (fAAA, 9% vs spAAA, 11%; P = .75). Additionally, fAAA patients did not incur any significant difference in major adverse events following EVAR (fAAA, 4% vs spAAA, 5%; P = .70). Patients with fAAA did have a significantly increased rate of endoleak (fAAA, 24% vs spAAA, 12%; P = .03) and secondary intervention following EVAR (fAAA, 21% vs spAAA, 12%; P = .04).

CONCLUSIONS

The current study shows that patients with fAAA do not have increased perioperative morbidity following open or endovascular AAA repair. However, patients with fAAA do have an increased risk of endoleak and secondary intervention following EVAR. These findings suggest that EVAR and open AAA repair are both safe and effective for fAAA patients. The increased rate of endoleak and secondary intervention in patients with fAAA suggests that this subpopulation may benefit from closer post-EVAR surveillance or open surgical repair in good risk patients.

The potential role of DNA methylation in abdominal aortic aneurysms

Abdominal aortic aneurysm (AAA) is a complex disorder that has a significant impact on the aging population. While both genetic and environmental risk factors have been implicated in AAA formation, the precise genetic markers involved and the factors influencing their expression remain an area of ongoing investigation. DNA methylation has been previously used to study gene silencing in other inflammatory disorders and since AAA has an extensive inflammatory component, we sought to examine the genome-wide DNA methylation profiles in mononuclear blood cells of AAA cases and matched non-AAA controls. To this end, we collected blood samples and isolated mononuclear cells for DNA and RNA extraction from four all male groups: AAA smokers (n = 11), AAA non-smokers (n = 9), control smokers (n = 10) and control non-smokers (n = 11). Methylation data were obtained using the Illumina 450k Human Methylation Bead Chip and analyzed using the R language and multiple Bioconductor packages. Principal component analysis and linear analysis of CpG island subsets identified four regions with significant differences in methylation with respect to AAA: kelch-like family member 35 (KLHL35), calponin 2 (CNN2), serpin peptidase inhibitor clade B (ovalbumin) member 9 (SERPINB9), and adenylate cyclase 10 pseudogene 1 (ADCY10P1). Follow-up studies included RT-PCR and immunostaining for CNN2 and SERPINB9. These findings are novel and suggest DNA methylation may play a role in AAA pathobiology.

Endoleak visualized with carbon dioxide angiography during endovascular aneurysm repair using the Endurant stent-graft

PURPOSE

To make interventionists aware of the potential for type IV endoleak on completion carbon dioxide (CO2) angiography during endovascular aneurysm repair (EVAR) using the Endurant stent-graft.

CASE REPORT

A 74-year-old man with chronic kidney disease underwent EVAR with an Endurant stent-graft using CO2 angiography to guide graft placement. Completion CO2 angiography demonstrated immediate accumulation of CO2 in the aneurysm sac suggestive of an endoleak, but confirmatory angiography with conventional iodinated contrast showed no evidence of an endoleak. We speculate that this is a type IV endoleak, and graft porosity may be responsible.

CONCLUSION

Interventionists should be alerted to the possibility of visualizing these endoleaks through Endurant stent-grafts under CO2 angiography. Further work should be done to elucidate the exact mechanism of the endoleak.

Abstract 494: Proinflammatory Role of Stem Cells in Abdominal Aortic Aneurysms

Background: The pathogenesis of abdominal aortic aneurysm (AAA) formation includes inflammation, vascular smooth muscle cell apoptosis, extracellular matrix degradation and oxidative stress. It is well established that multi-potent stem cells have an important role in cardiovascular health and disease but the role of stem cells in AAA formation remains controversial. We sought to describe the presence of stem cells in human AAA tissue. Additionally, we investigated the differentiation of stem cells within the aneurysmal aorta.

Methods: Infra-renal aortic wall specimens (8 AAA patients; 5 males and 3 females; ages ranging from 55 to 78 years) were collected from patients undergoing AAA repair operations. Non-aneurysmal infra-renal aortic control samples were collected at autopsies (N=5; 3 males and 2 females; donor ages ranging from 53 to 78 years). Using immunohistochemistry, we compared the abundance of STRO1+, cKit+, and CD34+ cells in aortic tissue. Using double immunofluorescence staining, we evaluated stem cell differentiation into smooth muscle cells (SM22), fibroblasts (FSP1), and macrophages (CD68).

Results: Both the media and adventitia of infra-renal AAA samples demonstrated a significantly greater number of STRO1+, c-Kit+ and CD34+ cells when compared with matched non-aneurysmal control aortic tissues. Furthermore, double immunofluorescence staining identified that AAA stem cells express the macrophage marker CD68 but not the smooth muscle cell marker SM22 or the fibroblast marker FSP1.

Conclusions: Stem cells are significantly elevated in infra-renal AAA tissue compared to matched control aortic tissue. Our data also demonstrate that AAA stem cells express macrophage surface antigens but not smooth muscle cell or fibroblast markers. These finding suggest an inflammatory/immune role of stem cells during AAA pathogenesis.

Intravascular lipoma of the internal jugular vein

Benign primary venous tumors are rare. While venous lipomas have been reported in the vena cava, their incidence in the remainder of the venous circulation is less well known. We present what we believe to be the first reported case of an intravascular lipoma arising from the internal jugular vein. The clinical presentation, imaging characteristics, and histologic features are presented. We also performed a review of the current literature.

Abstract 382: Anti-MAA Antibodies in Sprague Dawley Rats are Increased in Response to a High Fat Western Diet

Introduction

Malondialdehyde/Acetaldehyde (MAA) modified proteins have been suggested to play a role in the development/progression of atherosclerosis. Circulating antibodies directed against these proteins have recently been shown to be associated with the severity of the disease. More specifically, the isotype of the antibody to MAA correlated with either an acute MI (IgG) or stable plaque formation (IgA) formation. MAA is thought to form as a result of the oxidation of fat(s) and thus the concentration and antibody response should reflect the amount of fat in the diet.

Objective

The purpose of this study was to evaluate the antibody responses to MAA modified proteins following immunization and high fat western diet feeding in rats.

Methods

Male Sprague Dawley rats were immunized with MAA-modified protein weekly for 5 weeks and then assayed for antibodies to these proteins. Animals were then separated into the following groups: chow sham, chow MAA immunized, high fat sham, and high fat MAA immunized. The high fat animals were fed a Western diet with 2-thiouracil for 12 weeks, bled every 3 weeks, and serum assayed for the presence of circulating MAA antibodies.

Results

Prior to feeding with high fat diet, rats immunized with MAA-modified protein had a significant increase (P<0.001) in serum antibodies directed against these modified proteins compared to controls (N of 4 per group). Following feeding of high fat diet antibody concentrations increased 6 fold in the high fat MAA immunized group compared to the chow MAA immunized group (P<0.05). Antibodies in the high fat sham and chow sham had only minimal increases in antibodies to these proteins.

Conclusions

These data demonstrate that following immunization with MAA-modified proteins, circulating antibodies are produced that increase following consumption of a high fat Western diet. It suggests that MAA-modified proteins are produced at low levels following normal diet, producing antibodies which act as a normal clearance method for altered protein. When high fat consumption increases these antibody levels are increased in response to the oxidative stress.

Implications

Use of these antibodies as a biomarker in the future may help predict the onset or progression of atherosclerosis.

Abstract 332: Genomically Enhanced Risk Stratification in Abdominal Aortic Aneurysm Repair

OBJECTIVE

The purpose of this study was to investigate the association between selected single-nucleotide polymorphisms (SNPs), associated with abdominal aortic aneurysms (AAA) in previous genome-wide association studies, and major adverse events following AAA repair

METHODS

Genomic DNA was isolated from blood samples collected from AAA patients and used for genotyping. A genetic risk score was constructed using five SNPs known to be associated with AAA. Epidemiologic data were extracted from the electronic medical record and analyzed retrospectively. Major adverse events were defined as myocardial infarction, cardiac arrest, respiratory failure requiring tracheostomy, renal failure requiring dialysis, colonic ischemia requiring resection, limb ischemia requiring operation, multi-system organ failure or death.

RESULTS

Three hundred and twenty one patients (267 male, 83%) with complete genomic and clinical data underwent AAA repair from 2004-2012. Demographics were consistent with a standard AAA population. 204 patients (64%) underwent endovascular repair and 117 (36%) underwent conventional open surgical repair. Quality control checks were performed on the clinical and laboratory data and none of the 5 selected SNPs deviated from the Hardy-Weinberg Equilibrium. Stepwise logistic regression was then used to determine the most parsimonious model of variables associated with adverse outcomes from AAA repair. Serum creatinine, height, resting heart rate, diastolic blood pressure and the genetic risk score remained in the model. The Hosmer and Lemeshow test of deviation from goodness-of-fit (p = 0.56) indicated that the data fit the model well. The regression coefficients from this model will be used to construct a clinician-friendly risk calculator to help identify patients at increased risk for a major adverse event following AAA repair.

CONCLUSIONS

Selected SNPs help identify patients at risk for major adverse events following AAA repair. Incorporating genetic data, especially in patients with few clinical risk factors, may result in a better preoperative risk assessment.

IL-6 and its receptors in coronary artery disease and acute myocardial infarction

Biomarkers such as interleukin-6 (IL-6), soluble interleukin-6 receptor (sIL-6R), and high sensitive C-reactive protein (hsCRP) have been reported to be elevated in acute myocardial infarction (AMI). The aim of this study is to determine the relationship between these markers during AMI, as well as their relationship to clinical parameters in an effort to discern their predictive potential in cardiac events. Serum was collected from 73 patients with; AMI, stable coronary artery disease (CAD), and controls during cardiac catheterization. Biomarker levels were determined and correlated with clinical data. IL-6 (11.75pg/ml, P<0.05) and sIL-6R (41,340pg/ml, P=0.05) were elevated in AMI compared with CAD and controls. At presentation, hsCRP was elevated in AMI patients (4.69mg/L) compared to controls (2.69mg/L, P<0.05); however, there was a significant decrease in hsCRP between AMI (4.69mg/L) and CAD patients (7.4mg/L, P<0.05). After 24h post-AMI hsCRP levels were increased compared to stable CAD (60.46mg/L, P<0.05) and were preceded by increased IL-6 at presentation. Soluble Gp130 (sGp130) showed no significant change between AMI, CAD, and control patients. However, sGp130 positively correlated with peak troponin in AMI (R=0.587, P<0.01), and negatively correlated with previous AMI (R=-0.382, P<0.05). Circulating monocyte mRNA expression isolated from selected AMI patients showed an increase in IL-6 mRNA (5.28-fold, P<0.01) and a decrease in both IL-6R (0.374-fold, P<0.01) and sGp130 mRNA (0.38-fold, P<0.01) as compared to CAD and controls. Results demonstrate that IL-6 and sIL-6R are associated with AMI and cardiac injury. These data support the hypothesis that trans-IL-6 receptor binding may alter intracellular signaling, and blocking of IL-6 receptor binding may be pathogenic in AMI. These data may be predictive of mechanism(s) by which plaques become unstable and rupture.

Ultrasound imaging in an animal model of vascular inflammation following balloon injury

Cardiovascular disease is a major cause of morbidity and mortality in the world and better prevention and treatment strategies are needed. Studies from this laboratory have shown that perfluorocarbon exposed sonicated dextrose albumin (PESDA) microbubbles bind to inflamed vasculature through interactions with scavenger receptors (SR). This current study details the use of PESDA as a tool for accessing and quantifying the extent of vascular inflammation. Angioplastied rat aortas were evaluated with low mechanical index microbubble imaging techniques contrast pulse sequencing (CPS); Siemens Acuson Sequoia 15L8, 7-15 MHz ultrasound probe with a mechanical index of 0.09 to detect microbubble binding. Real-time polymerase chain reaction (RT-PCR) analysis of angioplastied aortas demonstrated a significantly (p < 0.01) increased expression of both SRs and Interleukin 6 (IL-6). Vessel wall enhancement was quantified using densitometry of CPS ultrasound images and correlated with the upregulated expression of scavenger receptors, Toll-like receptors and IL-6. This study demonstrates that PESDA, in conjunction with CPS ultrasound, is an effective imaging technique to better detect early vascular inflammation and potential cardiovascular disease.

Novel pathways in the pathobiology of human abdominal aortic aneurysms

OBJECTIVES

Abdominal aortic aneurysm (AAA), a dilatation of the infrarenal aorta, typically affects males >65 years. The pathobiological mechanisms of human AAA are poorly understood. The goal of this study was to identify novel pathways involved in the development of AAAs.

METHODS

A custom-designed 'AAA-chip' was used to assay 43 of the differentially expressed genes identified in a previously published microarray study between AAA (n = 15) and control (n = 15) infrarenal abdominal aorta. Protein analyses were performed on selected genes.

RESULTS

Altogether 38 of the 43 genes on the 'AAA-chip' showed significantly different expression. Novel validated genes in AAA pathobiology included ADCY7, ARL4C, BLNK, FOSB, GATM, LYZ, MFGE8, PRUNE2, PTPRC, SMTN, TMODI and TPM2. These genes represent a wide range of biological functions, such as calcium signaling, development and differentiation, as well as cell adhesion not previously implicated in AAA pathobiology. Protein analyses for GATM, CD4, CXCR4, BLNK, PLEK, LYZ, FOSB, DUSP6, ITGA5 and PTPRC confirmed the mRNA findings.

CONCLUSION

The results provide new directions for future research into AAA pathogenesis to study the role of novel genes confirmed here. New treatments and diagnostic tools for AAA could potentially be identified by studying these novel pathways.

Abstract 447: Foam Cell Formation and Triglyceride Production After Incubation of Human Monocytes and Endothelial Cells with MAA-Modified Proteins

Introduction: Oxidized proteins and the formation of foam cells are central aspects in the development and progression of atherosclerosis. Malondialdehyde acetaldehyde (MAA) modified low density lipoprotein (LDL) is generated when lipoproteins are exposed to the oxidative product malondialdehyde. These MAA-adducted proteins have been shown to bind scavenger receptors, up-regulate adhesion molecules, induce cytokine expression, and initiate antibody and T-cell responses in both human and animal models of atherosclerotic disease. However, the induction of foam cells using these antigens has been untested.

Objective: The purpose of this study was to evaluate the ability of MAA-adducted proteins on LDL to induce foam cell formation and upregulate innate inflammatory mediators of atherosclerosis in human peripheral monocytes, mouse macrophage, and human aortic endothelial cell lines.

Methods: Mouse aortic endothelial (2167), mouse macrophage (J774) and human peripheral monocytes were incubated with LDL, oxidized-LDL, MAA-LDL, or MAA-human albumin (25 and 50 ng/ml) for 24 or 48 hours and evaluated. Cells were accessed for uptake using Oil Red O, triglyceride production, and cholesterol esters using filipin. Real-time semi-quantitative RT-PCR and ELISA was performed to evaluate IL-6 and monocyte chemotactic protein-1 (MCP-1) mRNA expression and protein secretion. MAA binding was also assessed using an anti-MAA monoclonal antibody.

Results: LDL uptake is increased in aortic endothelial cells, J774 and human monocytes as evidenced by filipin and Oil Red O staining for esterified cholesterol LDL as compared to sham controls. Triglyceride data show a 5.1 fold increase in monocytes and a 6 fold increase in aortic endothelial cells increase following MAA-LDL incubation over control p<0.001. Additionally, IHC for MAA-adducted proteins after incubation with MAA-modified demonstrate surface binding and intracellular uptake of MAA-adducted proteins. Incubation of MAA-albumin and MAA-LDL with aortic endothelial cells results in significant IL-6 and MCP-1 mRNA synthesis and protein expression 5 fold for IL-6 p<0.001 and 3 fold for MCP-1 p<0.01

Conclusions: These data show that MAA-modified proteins bind to and are processed by endothelial cells, macrophage, and human monocytes. MAA-modified proteins result in the production of innate immune mediators of tissue inflammation and inflammation recruitment. The direct effect of MAA in forming “foam cells” as evidenced by increased triglyceride and cholesterol is supportive for a role of MAA-modified proteins in the progression of atherosclerosis. The nature and impact of MAA-modification is hypothesized to be central to cellular apoptosis, autophagy and/or necrosis.

Implications: MAA-modified proteins may be directly pathogenic in the development of plaque inflammation and progression of atherosclerosis.

Regional expression of HOXA4 along the aorta and its potential role in human abdominal aortic aneurysms

BACKGROUND

The infrarenal abdominal aorta exhibits increased disease susceptibility relative to other aortic regions. Allograft studies exchanging thoracic and abdominal segments showed that regional susceptibility is maintained regardless of location, suggesting substantial roles for embryological origin, tissue composition and site-specific gene expression.

RESULTS

We analyzed gene expression with microarrays in baboon aortas, and found that members of the HOX gene family exhibited spatial expression differences. HOXA4 was chosen for further study, since it had decreased expression in the abdominal compared to the thoracic aorta. Western blot analysis from 24 human aortas demonstrated significantly higher HOXA4 protein levels in thoracic compared to abdominal tissues (P < 0.001). Immunohistochemical staining for HOXA4 showed nuclear and perinuclear staining in endothelial and smooth muscle cells in aorta. The HOXA4 transcript levels were significantly decreased in human abdominal aortic aneurysms (AAAs) compared to age-matched non-aneurysmal controls (P < 0.00004). Cultured human aortic endothelial and smooth muscle cells stimulated with INF-γ (an important inflammatory cytokine in AAA pathogenesis) showed decreased levels of HOXA4 protein (P < 0.0007).

CONCLUSIONS

Our results demonstrated spatial variation in expression of HOXA4 in human aortas that persisted into adulthood and that downregulation of HOXA4 expression was associated with AAAs, an important aortic disease of the ageing population.

Role of complement cascade in abdominal aortic aneurysms

OBJECTIVE

The goal of this study was to investigate the role of complement cascade genes in the pathobiology of human abdominal aortic aneurysms (AAAs).

METHODS AND RESULTS

Results of a genome-wide microarray expression profiling revealed 3274 differentially expressed genes between aneurysmal and control aortic tissue. Interestingly, 13 genes in the complement cascade were significantly differentially expressed between AAA and the controls. In silico analysis of the promoters of the 13 complement cascade genes showed enrichment for transcription factor binding sites for signal transducer and activator of transcription (STAT)5A. Chromatin-immunoprecipitation experiments demonstrated binding of transcription factor STAT5A to the promoters of the majority of the complement cascade genes. Immunohistochemical analysis showed strong staining for C2 in AAA tissues.

CONCLUSIONS

These results provide strong evidence that the complement cascade plays a role in human AAA. Based on our microarray studies, the pathway is activated in AAA, particularly via the lectin and classical pathways. The overrepresented binding sites of transcription factor STAT5A in the complement cascade gene promoters suggest a role for STAT5A in the coordinated regulation of complement cascade gene expression.

Malondialdehyde-acetaldehyde adduct is the dominant epitope after MDA modification of proteins in atherosclerosis

Antibodies to malondialdehyde (MDA)-modified macromolecules (adducts) have been detected in the serum of patients with atherosclerosis and correlate with the progression of this disease. However, the epitope and its formation have not been characterized. Studies have shown that excess MDA can be degraded to acetaldehyde, which combines with proteins to from a stable dihydropyridine adduct. To investigate, mice were immunized with MDA adducts in the absence of adjuvant and showed an increase in antibodies to MDA adducts and the carrier protein as the concentration of MDA was increased. In fact, a number of the commercially available antibodies to MDA-modified proteins were able to be inhibited by a chemical analogue, hexyl-MAA. Also, MDA-MAA adducts were detected in the serum and aortic tissue of JCR diabetic/atherosclerotic rats. These studies determined that commercially available antibodies to MDA predominantly react with the MAA adduct and are present in the JCR model of atherosclerosis in both the serum and the aortic tissue. Therefore, the immune response to MDA-modified proteins is most probably to the dihydropyridine structure (predominant epitope in MAA), which suggests that MAA adducts may play a role in the development and/or progression of atherosclerosis.

Albumin-based microbubbles bind up-regulated scavenger receptors following vascular injury

We have shown previously that perfluorocarbon-exposed sonicated dextrose albumin (PESDA) microbubbles bind to injured vascular tissue and can be detected with ultrasound imaging techniques. Prior studies have shown that scavenger receptors (SRs) are regulators of innate and adaptive immune responses and are involved in the progression of vascular disease such as atherosclerosis. In this study, we sought to determine the molecular mechanism of PESDA binding to balloon-injured vasculature. RT-PCR analysis of angioplastied aortas demonstrated a significantly (p ≤ 0.01) increased expression of SRs. Binding to SRs was confirmed using SR-expressing CHO cells, and this binding was blocked by competitive inhibition with the SR-binding ligands oxidized LDL and malondialdehyde-acetaldehyde-modified LDL. Confocal imaging confirmed the co-localization of PESDA microbubbles to CD36, SRB-1, and Toll-like receptor 4, but not to monocytes/macrophages. This study demonstrates that PESDA binds to SRs and that this binding is in major part dependent upon the oxidized nature of PESDA microbubble shell proteins. The extent of SR mRNA expression was increased with injury and associated with microbubble retention as defined by scanning electron microscopy and immunohistochemistry. These findings clarify the mechanisms of how albumin-based microbubbles bind to injured and inflamed vasculature and further support the potential of this imaging technique to detect early vascular innate inflammatory pathophysiologic processes.

Ileal perforation secondary to Clostridium difficile enteritis: report of 2 cases

Two cases of small-bowel perforation secondary to Clostridium difficile enteritis are described and compared with the 8 cases of C difficile enteritis reported in the medical literature. The cause of small-bowel involvement with C difficile is unknown, but prior antibiotic use, prior colectomy, chronic alterations in small-bowel flora, and other host factors are discussed.