Atherosclerosis and abdominal aortic aneurysm: cause, response, or common risk factors?

A peptide antagonist of thrombospondin-1 promotes abdominal aortic aneurysm progression in the angiotensin II-infused apolipoprotein-E-deficient mouse

OBJECTIVE

Interaction of the activating sequence in thrombospondin-1 (TSP-1) with the conserved sequence (leucine-serine-lysine-leucine [LSKL]) in the latency-associated peptide region of latent transforming growth factor (TGF)-β complex is important in regulating TGF-β1 activity. We aimed to assess the effect of blocking peptide LSKL on the progression of pre-established abdominal aortic aneurysm in angiotensin II-infused apolipoprotein E-deficient (ApoE(-/-)) mice.

APPROACH AND RESULTS

Abdominal aortic aneurysm was established in 3-month-old male ApoE(-/-) mice with subcutaneous infusion of angiotensin II for 28 days. After this, mice received LSKL peptide or control SLLK (serine-leucine-leucine-lysine) peptide (4 mg/kg) via daily intraperitoneal injection for an additional 2 weeks. Administration of LSKL peptide promoted larger suprarenal aortic diameter, as determined by ultrasound and morphometric analysis, and stimulated more severe atherosclerosis within the aortic arch. In addition, mice receiving LSKL peptide exhibited elevated circulating proinflammatory cytokine levels and greater inflammatory cells within the suprarenal aorta compared with controls. Mice receiving LSKL peptide showed low plasma TGF-β1 activity and low levels of aortic tissue phosphorylated to total Smad2/3. Aortic gene expression of TGF-β receptor 1 (TGFBRI) and receptor 2 (TGFBRII), but not TGF-β1 and thrombospondin-1, were lower in mice receiving LSKL peptide than controls. LSKL peptide administration was associated with greater aortic elastin fragmentation and lower expression and activity of the TGF-β1-target gene lysyl oxidase like 1 (LOXL1).

CONCLUSIONS

Attenuation of thrombospondin-1-directed activation of TGF-β1 promotes abdominal aortic aneurysm and atherosclerosis progression in the angiotensin II-infused ApoE(-/-) mouse model.

B2 cells suppress experimental abdominal aortic aneurysms

Recent reports of rupture in patients with abdominal aortic aneurysm (AAA) receiving B-cell depletion therapy highlight the importance of understanding the role of B cells (B1 and B2 subsets) in the development of AAA. We hypothesized that B2 cells aggravate experimental aneurysm formation. The IHC staining revealed infiltration of B cells in the aorta of wild-type (C57BL/6) mice at day 7 after elastase perfusion and persisted through day 21. Quantification of immune cell types using flow cytometry at day 14 showed significantly greater infiltration of mononuclear cells, including B cells (B2: 93% of total B cells) and T cells in elastase-perfused aortas compared with saline-perfused or normal aortas. muMT (mature B-cell deficient) mice were prone to AAA formation similar to wild-type mice in two different experimental AAA models. Contradicting our hypothesis, adoptive transfer of B2 cells suppressed AAA formation (102.0% ± 7.3% versus 75.2% ± 5.5%; P < 0.05) with concomitant increase in the splenic regulatory T cell (0.24% ± 0.03% versus 0.92% ± 0.23%; P < 0.05) and decrease in aortic infiltration of mononuclear cells. Our data suggest that B2 cells constitute the largest population of B cells in experimental AAA. Furthermore, B2 cells, in the absence of other B-cell subsets, increase splenic regulatory T-cell population and suppress AAA formation.

Visceral adiposity is not associated with abdominal aortic aneurysm presence and growth

Previous studies in rodent models and patients suggest that visceral adipose could play a direct role in the development and progression of abdominal aortic aneurysm (AAA). This study aimed to assess the association of visceral adiposity with AAA presence and growth. This study was a case-control investigation of patients that did (n=196) and did not (n=181) have an AAA who presented to The Townsville Hospital vascular clinic between 2003 and 2012. Cases were patients with AAA (infra-renal aortic diameter >30 mm) and controls were patients with intermittent claudication but no AAA (infra-renal aortic diameter <30 mm). All patients underwent computed tomography angiography (CTA). The visceral to total abdominal adipose volume ratio was estimated from CTAs by assessing total and visceral adipose deposits using an imaging software program. Measurements were assessed for reproducibility by repeat assessments on 15 patients. AAA risk factors were recorded at entry. Forty-five cases underwent two CTAs more than 6 months apart to assess AAA expansion. The association of visceral adiposity with AAA presence and growth was examined using logistic regression. Visceral adipose assessment by CTA was highly reproducible (mean coefficient of variation 1.0%). AAA was positively associated with older age and negatively associated with diabetes. The visceral to total abdominal adipose volume ratio was not significantly associated with AAA after adjustment for other risk factors. Patients with a visceral to total abdominal adipose volume ratio in quartile four had a 1.63-fold increased risk of AAA but with wide confidence intervals (95% CI 0.71-3.70; p=0.248). Visceral adiposity was not associated with AAA growth. In conclusion, this study suggests that visceral adiposity is not specifically associated with AAA presence or growth although larger studies are required to confirm these findings.

Bacteria and bacterial DNA in atherosclerotic plaque and aneurysmal wall biopsies from patients with and without periodontitis

Background

Several studies have reported an association between chronic periodontitis (CP) and cardiovascular diseases. Detection of periodontopathogens, including red complex bacteria (RCB), in vascular lesions has suggested these bacteria to be involved in the pathogenesis of atherosclerosis and abdominal aortic aneurysms.

Objective

In this study, we investigate bacteria and their DNA in vascular biopsies from patients with vascular diseases (VD; i.e. abdominal aortic aneurysms, atherosclerotic carotid, and common femoral arteries), with and without CP.

Methods

DNA was extracted from vascular biopsies selected from 40 VD patients: 30 with CP and 10 without CP. The V3-V5 region of the 16S rDNA (V3-V5) was polymerase chain reaction (PCR)-amplified, and the amplicons were cloned into Escherichia coli, sequenced, and classified (GenBank and the Human Oral Microbiome database). Species-specific primers were used for the detection of Porphyromonas gingivalis. In addition, 10 randomly selected vascular biopsies from the CP group were subjected to scanning electron microscopy (SEM) for visualization of bacteria. Checkerboard DNA–DNA hybridization was performed to assess the presence of RCB in 10 randomly selected subgingival plaque samples from CP patients.

Results

A higher load and mean diversity of bacteria were detected in vascular biopsies from VD patients with CP compared to those without CP. Enterobacteriaceae were frequently detected in vascular biopsies together with cultivable, commensal oral, and not-yet-cultured bacterial species. While 70% of the subgingival plaque samples from CP patients showed presence of RCB, only P. gingivalis was detected in one vascular biopsy. Bacterial cells were seen in all 10 vascular biopsies examined by SEM.

Conclusions

A higher bacterial load and more diverse colonization were detected in VD lesions of CP patients as compared to patients without CP. This indicated that a multitude of bacterial species both from the gut and the oral cavity, rather than exclusively periodontopathogens, may be involved as additional risk factors in the pathogenesis of VD.

Comparison of the serum lipidome in patients with abdominal aortic aneurysm and peripheral artery disease

BACKGROUND

Currently, the relationship between circulating lipids and abdominal aortic aneurysm (AAA) is unclear. We conducted a lipidomic analysis to identify serum lipids associated with AAA presence. Secondary analyses assessed the ability of models incorporating lipidomic features to improve stratification of patient groups with and without AAA beyond traditional risk factors.

METHODS AND RESULTS

Serum lipids were profiled via liquid chromatography tandem mass spectrometry analysis of serum from 161 patients with AAA and 168 controls with peripheral artery disease. Binary logistic regression was used to identify AAA-associated lipids. Classification models were created based on a combination of (1) traditional risk factors only or (2) lipidomic features and traditional risk factors. Model performance was assessed using receiver operator characteristic curves. Three diacylglycerols and 7 triacylglycerols were associated with AAA. Combining lipidomic features with traditional risk factors significantly improved stratification of AAA and peripheral artery disease groups when compared with traditional risk factors alone (mean area under the receiver operator characteristic curve [95% confidence interval], 0.760 [0.756-0.763] and 0.719 [0.716-0.723], respectively; P<0.05).

CONCLUSIONS

A group of linoleic acid containing triacylglycerols and diacylglycerols were significantly associated with AAA presence. Inclusion of lipidomic features in multivariate analyses significantly improved prediction of AAA presence when compared with traditional risk factors alone.

Prognostic value of tissue factor in patients with abdominal aortic and iliac arterial aneurysms - preliminary study

INTRODUCTION

The decision on the time and choice of strategy of treatment of abdominal aortic aneurysm must be especially carefully balanced. The aim of the study was to evaluate the tissue factor (TF) plasma level as a potential factor useful in anticipation of abdominal aortic aneurysm and/or iliac arterial aneurysm via comparison of plasma TF level in patients with ruptured and non-ruptured aneurysms.

MATERIAL AND METHODS

The study included 33 patients with aneurysm (17 operated on electively because of non-ruptured aneurysm and 16 operated on emergently due to ruptured aneurysm), 33 claudicant patients with atherosclerosis of the abdominal aorta and iliac arteries with normal diameter of arteries, and 30 healthy controls. Plasma TF level was assessed by ELISA method using the IMUBIND Tissue Factor ELISA Kit (American Diagnostica Inc.).

RESULTS

The study showed an increased TF level in patients with aneurysm (134 ±54 pg/ml) and in patients with atherosclerosis without concomitant aneurysm (91 ±30 pg/ml) in comparison with the control group (62 ±20 pg/ml), respectively p < 0.001 and p = 0.008. A significantly higher TF plasma level was observed in patients with ruptured abdominal aortic aneurysms (160 ±57 pg/ml) as compared to patients with non-ruptured aortic aneurysms (109 ±39 pg/ml) or peripheral arterial occlusive disease (91 ±30 pg/ml), respectively p < 0.001 and p < 0.001. The difference in TF level between the group with non-ruptured aortic aneurysms (109 ±39 pg/ml) and the patients with atherosclerosis without aneurysm (91 ±30 pg/ml) was not statistically significant.

CONCLUSIONS

No difference in TF level between patients with non-ruptured AAA/IAA and patients with aortic and iliac atherosclerosis without aneurysm indicates that an increased TF plasma level is not specific for any of the above-mentioned vascular pathologies.

Quercetin reduces oxidative stress and inhibits activation of c‑Jun N‑terminal kinase/activator protein‑1 signaling in an experimental mouse model of abdominal aortic aneurysm

Oxidative stress is becoming increasingly linked to the pathogenesis of abdominal aortic aneurysms (AAAs). The antioxidant activity of flavonoids has attracted attention for their possible role in the prevention of cardiovascular diseases. The purpose of this study was to determine whether an antioxidant mechanism is involved in the aneurysm formation inhibitory effect afforded by quercetin. Male C57/BL6 mice received quercetin continuously from 2 weeks prior to and 6 weeks following the AAA induction with extraluminal CaCl2. Quercetin treatment decreased AAA incidence and inhibited the reactive oxygen species generation, nitrotyrosine formation and lipid peroxidation production in the aortic tissue during AAA development. In addition, quercetin‑treated mice exhibited significantly lower expression of the p47phox subunit of nicotinamide adenine dinucleotide phosphate oxidase and inducible nitric oxide synthase, as well as coordinated downregulation of manganese‑superoxide dismutase activities and glutathione peroxidase (GPx)‑1 and GPx‑3 expression. Quercetin also blunted the expression of c‑Jun N‑terminal kinase (JNK) and phospho‑JNK and, in addition, diminished activation of the activator protein (AP)‑1 transcription factor. Gelatin zymography showed that quercetin eliminated matrix metalloproteinase (MMP)‑2 and MMP‑9 activation during AAA formation. In conclusion, the inhibitory effects of quercetin on oxidative stress and MMP activation, through modulation of JNK/AP‑1 signaling, may partly account for its benefit in CaCl2‑induced AAA.

Advanced atherosclerosis is associated with increased medial degeneration in sporadic ascending aortic aneurysms

OBJECTIVE

The pathogenesis of non-familial, sporadic ascending aortic aneurysms (SAAA) is poorly understood, and the relationship between ascending aortic atherosclerosis and medial degeneration is unclear. We evaluated the prevalence and severity of aortic atherosclerosis and its association with medial degeneration in SAAA.

METHODS AND RESULTS

Atherosclerosis was characterized in ascending aortic tissues collected from 68 SAAA patients (mean age, 62.9 ± 12.0 years) and 15 controls (mean age, 56.6 ± 11.4 years [P = 0.07]) by using a modified American Heart Association classification system. Upon histologic examination, 97% of SAAA patients and 73% of controls showed atherosclerotic changes. Most SAAA samples had intermediate (types 2 and 3, 35%) or advanced atherosclerosis (types ≥ 4; 40%), whereas most control samples showed minimal atherosclerosis (none or type 1, 80%; P < 0.001 after adjusting for age). In a separate analysis, we examined the total incidence and grade distribution of medial degenerative changes among SAAA samples according to atherosclerosis grade. Advanced atherosclerosis was associated with higher grades of smooth muscle cell depletion (P < 0.001), elastic fiber depletion (P = 0.02), elastic fiber fragmentation (P < 0.001), and mucopolysaccharide accumulation (P = 0.04). Aortic diameter was larger in SAAA patients with advanced atherosclerosis than in patients with minimal (P = 0.04) or intermediate atherosclerosis (P = 0.04). Immunostaining showed marked CD3+ T-cell and CD68+ macrophage infiltration, MMP-2 and MMP-9 production, and cryopyrin expression in the medial layer adjacent to atherosclerotic plaque.

CONCLUSIONS

SAAA tissues exhibited advanced atherosclerosis that was associated with severe medial degeneration and increased aortic diameter. Our findings suggest a role for atherosclerosis in the progression of sporadic ascending aortic aneurysms.

Evaluation of acute abdominal pain

Abdominal pain is a common complaint encountered in primary care and in the ED. Varying levels of pain dictate the immediacy of the intervention. Time is vital when making the decision to initiate therapeutic interventions. A comprehensive assessment with physical exam and diagnostic studies is required.

Cathepsins: a new culprit behind abdominal aortic aneurysm

Abdominal aortic aneurysm (AAA) is a fatal disease defined as an abdominal aortic diameter of 3.0 cm or more, where the abdominal aorta exceeds the normal diameter by more than 50%. Histopathological changes of AAA mainly include extracellular matrix (ECM) remodeling at the abdominal aorta wall, but there is lack of specific drugs to treat AAA. Recent studies have reported that lysosomal cathepsins could induce vascular remodeling and AAA formation by regulating vascular inflammation, medial smooth muscle cell apoptosis, neovascularization, and protease expression. Thus, cathepsins are expected to become a new therapeutic target for AAA treatment.

Cyclophilin A: a key player for human disease

Cyclophilin A (CyPA) is a ubiquitously distributed protein belonging to the immunophilin family. CyPA has peptidyl prolyl cis-trans isomerase (PPIase) activity, which regulates protein folding and trafficking. Although CyPA was initially believed to function primarily as an intracellular protein, recent studies have revealed that it can be secreted by cells in response to inflammatory stimuli. Current research in animal models and humans has provided compelling evidences supporting the critical function of CyPA in several human diseases. This review discusses recently available data about CyPA in cardiovascular diseases, viral infections, neurodegeneration, cancer, rheumatoid arthritis, sepsis, asthma, periodontitis and aging. It is believed that further elucidations of the role of CyPA will provide a better understanding of the molecular mechanisms underlying these diseases and will help develop novel pharmacological therapies.

Natural regulatory T cells limit angiotensin II-induced aneurysm formation and rupture in mice

OBJECTIVE

Abdominal aortic aneurysm is an inflammatory disease leading to destructive vascular remodeling and ultimately to lethal aortic rupture. Despite its frequent association with atherosclerosis, compelling studies have shown striking differences and potentially opposite roles of T-cell helper responses in aneurysm as compared with atherosclerosis, casting doubt on the relevance and suitability of T-cell-targeted therapies in this context.

APPROACH AND RESULTS

Here, we show that selective depletion of T regulatory (Treg) cells using a CD25-specific monoclonal antibody significantly enhances the susceptibility of C57Bl/6 mice to angiotensin II-induced abdominal aortic aneurysm and promotes aortic rupture (n=25-44 mice/group). Similar results are observed in angiotensin II-treated Cd80(-/-)/Cd86(-/-) or Cd28(-/-) mice with impaired Treg cell homeostasis (n=18-23 mice/group). Treg cell depletion is associated with increased immune cell activation and a blunted interleukin (IL)-10 anti-inflammatory response, suggesting an immunoinflammatory imbalance. Interestingly, Il-10(-/-) mice (n=20 mice/group) show increased susceptibility to angiotensin II-induced abdominal aortic aneurysm and aortic rupture and are insensitive to Treg cell depletion. Finally, reconstitution of Cd28(-/-) Treg-deficient mice with Treg cells (n=22 mice/group) restores a balance in the immunoinflammatory response, rescues the animals from increased susceptibility to aneurysm, and prevents aortic dissection.

CONCLUSIONS

These results identify a critical role for Treg cells and IL-10 in the control of aneurysm formation and its progression to rupture and suggest that therapies targeting Treg responses may be most suited to treat aneurysmal disease.

Plasma levels of cathepsins L, K, and V and risks of abdominal aortic aneurysms: a randomized population-based study

BACKGROUND

Cathepsin L (CatL), cathepsin K (CatK), and cathepsin V (CatV) are potent elastases implicated in human arterial wall remodeling. Whether plasma levels of these cathepsins are altered in patients with abdominal aortic aneurysms (AAAs) remains unknown.

METHODS AND RESULTS

Plasma samples were collected from 476 male AAA patients and 200 age-matched male controls to determine CatL, CatK, and CatV levels by ELISA. Student's t-test demonstrated significantly higher plasma CatL levels in AAA patients than in controls (P < 0.0001), whereas CatK and CatV levels were lower in AAA patients than in controls (P = 0.052, P = 0.025). ROC curve analysis confirmed higher plasma CatL levels in AAA patients than in controls (P < 0.001). As potential confounders, current smoking and use of angiotensin-converting enzyme (ACE) inhibitors, aspirin, clopidogrel, and statins associated with significantly increased plasma CatL. Pearson's correlation test demonstrated that plasma CatL associated positively with CatS (r = 0.43, P < 0.0001), body-mass index (BMI) (r = 0.07, P = 0.047) and maximal aortic diameter (r = 0.29, P < 0.001), and negatively with lowest measured ankle-brachial index (ABI) (r = -0.22, P < 0.001). Plasma CatL remained associated positively with CatS (r = 0.43, P < 0.0001) and aortic diameter (r = 0.212, P < 0.001) and negatively with ABI (r = -0.10, P = 0.011) after adjusting for the aforementioned potential confounders in a partial correlation analysis. Multivariate logistic regression analysis indicated that plasma CatL was a risk factor of AAA before (odds ratio [OR] = 3.04, P < 0.001) and after (OR = 2.42, P < 0.001) the same confounder adjustment.

CONCLUSIONS

Correlation of plasma CatL levels with aortic diameter and the lowest ABI suggest that this cysteinyl protease plays a detrimental role in the pathogenesis of human peripheral arterial diseases and AAAs.

Increased levels of CD34+ cells are associated in patients with abdominal aortic aneurysms compared with patients with peripheral vascular disease

BACKGROUND

Circulating progenitor cells are integral to vascular health and effectively predict vascular reactivity. CD34 is a known marker of circulating progenitor cells. Few studies have examined the role of CD34+ cells in abdominal aortic aneurysm (AAA) disease and peripheral vascular disease (PVD). The aim of this study was to compare the percentage of CD34+ cells between patients with AAA versus PVD.

MATERIALS AND METHODS

We collected peripheral whole blood from AAA or PVD patients. The blood was stained with fluorescently labeled antibodies against CD34 or isotype controls. We collected data using a flow cytometer and analyzed them. We also recorded risk factors such as hypertension, diabetes, total cholesterol, serum white blood cells, serum creatinine, body mass index, blood pressure, statin use, current smoking status, coronary artery disease, cerebral vascular accident, and chronic obstructive pulmonary disease.

RESULTS

We enrolled 24 patients in this study (AAA, n = 12; PVD, n = 12). The AAA patients had a greater percentage of CD34+ cells compared with PVD patients. (r = 0.84; P = 0.016). There were no significant risk factors differences between AAA and PVD patients.

CONCLUSIONS

Based on CD34+ cell counts, AAA is a less severe vascular disease than PVD. Whether CD34+ cells can serve as a biomarker for risk stratification or a potential therapy warrants further study.

A sequence variant associated with sortilin-1 (SORT1) on 1p13.3 is independently associated with abdominal aortic aneurysm

Abdominal aortic aneurysm (AAA) is a common human disease with a high estimated heritability (0.7); however, only a small number of associated genetic loci have been reported to date. In contrast, over 100 loci have now been reproducibly associated with either blood lipid profile and/or coronary artery disease (CAD) (both risk factors for AAA) in large-scale meta-analyses. This study employed a staged design to investigate whether the loci for these two phenotypes are also associated with AAA. Validated CAD and dyslipidaemia loci underwent screening using the Otago AAA genome-wide association data set. Putative associations underwent staged secondary validation in 10 additional cohorts. A novel association between the SORT1 (1p13.3) locus and AAA was identified. The rs599839 G allele, which has been previously associated with both dyslipidaemia and CAD, reached genome-wide significance in 11 combined independent cohorts (meta-analysis with 7048 AAA cases and 75 976 controls: G allele OR 0.81, 95% CI 0.76-0.85, P = 7.2 × 10(-14)). Modelling for confounding interactions of concurrent dyslipidaemia, heart disease and other risk factors suggested that this marker is an independent predictor of AAA susceptibility. In conclusion, a genetic marker associated with cardiovascular risk factors, and in particular concurrent vascular disease, appeared to independently contribute to susceptibility for AAA. Given the potential genetic overlap between risk factor and disease phenotypes, the use of well-characterized case-control cohorts allowing for modelling of cardiovascular disease risk confounders will be an important component in the future discovery of genetic markers for conditions such as AAA.

Incidental abdominal aneurysms: a retrospective study of 13,115 patients who underwent a computed tomography scan

We evaluated the frequency and outcomes of abdominal aortic aneurysm (AAA) in Qatar. Data were collected retrospectively between 2004 and 2008 for all adult patients who underwent abdominal computed tomographic scanning for any reason. Patients with AAA were followed up for 3 years for aneurysmal rupture and mortality. Of the 13,115 patients screened, 61 (0.5%) patients had abdominal aneurysms. Most (82%) patients with AAA were male with mean age of 67 ± 12 years. The incidence of AAA substantially increased with age. Cardiovascular risk factors were prevalent among patients with AAA. The main location of AAA was infrarenal (67%), followed by thoracoabdominal (23%). The mean AAA diameter was 5.3 ± 2.5 cm. The rate of AAA rupture was 8% with a mortality rate of 60%; 80% of these were infrarenal, and 80% of them had a diameter of ≥5.5 cm. Overall mortality was 33%. This large study addressed the impact of screening for AAA in a population with high cardiovascular burden.

Everolimus limits aortic aneurysm in the apolipoprotein E-deficient mouse by downregulating C-C chemokine receptor 2 positive monocytes

OBJECTIVE

We aimed to determine the effect of mechanistic target of rapamycin inhibitor everolimus on abdominal aortic aneurysm within the angiotensin II (A2)-infused apolipoprotein E-deficient mouse model.

APPROACH AND RESULTS

Abdominal aortic aneurysm was induced via subcutaneous infusion of A2. Flow cytometry demonstrated increased circulating and aortic C-C chemokine receptor 2 (CCR2) monocytes during A2 infusion. The number of CCR2 monocytes present within the aorta was positively correlated with suprarenal aortic diameter. Simultaneous infusion of everolimus via a second subcutaneous osmotic micropump inhibited A2-induced aortic dilatation. Using flow cytometry and Western blot analysis, decreased aortic dilatation was associated with reduced development of CCR2 bone marrow monocytes, fewer numbers of circulating CCR2 monocytes, and lower aortic CCR2 concentration. In vitro, everolimus inhibited A2-stimulated production of interferon (IFN)-γ and IFNγ-induced CCR2 expression in apolipoprotein E-deficient mouse bone marrow monocytes. Further, everolimus diminished IFNγ/lipopolysaccharide-stimulated M1 polarization in apolipoprotein E-deficient mouse bone marrow monocyte-differentiated macrophages.

CONCLUSIONS

Systemic administration of everolimus limits aortic aneurysm in the A2-infused apolipoprotein E-deficient mouse model via suppressed development of bone marrow CCR2 monocytes and reduced egress of these cells into the circulation.

Standardization of outcome measures in clinical trials of pharmacological treatment for abdominal aortic aneurysm

An abdominal aortic aneurysm (AAA) is a common aortic wall disease with an increased prevalence in the elderly population (4-8% for those aged >65 years). Many AAAs are slow growing and remain insidious. Current standard of care for patients with small AAAs (<49 mm) is surveillance, with interventional therapy (open surgical repair or endovascular aneurysm repair) recommended for large (>50-55 mm), rapidly growing (>10 mm/year) or symptomatic AAAs. Although open surgical repair or endovascular aneurysm repair are effective, significant short- and long-term postoperative morbidity and mortality occurs. Currently, there is no pharmacological treatment specific for AAA; the need for the development of targeted pharmacological therapies based on clinically relevant and feasible outcomes acceptable to the medical community, regulatory agencies and third-party payers is high. A consensus on such end points will be critical to accelerating the development of pharmacological agents to prevent formation, arrest the expansion and reduce the rupture risk of AAA.

Statin therapy reduces growth of abdominal aortic aneurysms

BACKGROUND

The aim of this study was to evaluate the influence of statins on the growth of small abdominal aortic aneurysms (AAAs).

METHODS

We retrospectively examined AAA diameter in 211 patients who had undergone serial imaging surveillance.

RESULTS

Patients treated with and without statins were similar regarding age, initial aneurysm size, diagnosis of diabetes and hypertension, and smoking history. Patients receiving statins had a decreased aneurysm growth rate compared with those patients not receiving statins (0.9 mm/y [interquartile range, -1.0 to +1.0] vs 3.2 mm/y [interquartile range, 2.0-4.9], P < 0.0001). This difference in the rate of growth was maintained after adjusting for potential confounding factors.

CONCLUSIONS

To date, this is the one of the largest retrospective studies demonstrating an association between statin use and decreased growth rate of AAA.

Inverse association between the existence of coronary artery disease and progression of abdominal aortic aneurysm

OBJECTIVES

A strong degree of co-existence between coronary artery disease (CAD) and abdominal aortic aneurysm (AAA) is widely acknowledged, however, it remains to be elucidated whether the existence of CAD is associated with an accelerated expansion rate of AAA. Also, the relationship between preoperative CAD and postoperative major adverse cardiovascular events (MACE) has not been examined in Japanese patients. The aim of this study was to investigate the deleterious effects of CAD on the progression of AAA and the onset of postoperative MACE after elective AAA repair.

METHODS AND RESULTS

A retrospective cohort study of 665 consecutive Japanese patients who underwent elective surgical repair for infrarenal AAA at 2 high-volume Tokyo hospitals from 2003 through 2010 was performed. Preoperative CAD was shown to be a significant determinant of postoperative MACE (HR 2.29; 95%CI, 1.12-4.66; p=0.02). In the analysis of 510 patients for whom there were at least 2 follow-up CT scans of the size of their AAA before repair, the existence of CAD was shown to be inversely associated with the accelerated expansion rate of AAA.

CONCLUSION

This study on the patients undergone elective repair for infrarenal AAA identified an inverse association between the existence of CAD and progression of AAA as well as the significant impact of preoperative CAD on the occurrence of postoperative MACE after elective AAA repair.

Treatment with simvastatin inhibits the formation of abdominal aortic aneurysms in rabbits

BACKGROUND

Abdominal aortic aneurysm (AAA) is a common and lethal disease. AAAs are associated with atherosclerosis, chronic inflammation, and extracellular matrix degradation. The aim of this study was to determine whether treatment with simvastatin can influence the development of experimental aortic aneurysms in a rabbit model.

MATERIALS AND METHODS

A total of 76 rabbits were randomized in four groups: in group I (n = 12), where the abdominal aortas were exposed to 0.9% NaCl, and in group II (n = 24), group III (n = 24) and group IV (n = 18), where the aortas were exposed to CaCl2 0.5 mol/L for 15 minutes after laparotomy. Group III received 2 mg/kg simvastatin daily starting 7 days before laparotomy, and in group IV, the daily treatment with simvastatin started 7 days after laparotomy. Animals were sacrificed at intervals of first, second, third, and fourth week to obtain measurements of aortic diameter and histological examination. Moreover, immunohistochemistry was used in order to examine the relative distribution of matrix metalloproteinases (MMPs) 2 and 9 (MMP-2 and MMP-9, respectively) and tissue inhibitor 1 of MMPs within the aortic aneurysms.

RESULTS

The increase of aortic diameter in animals of group I ranged from 4.6% to 7.6%; in group II, from 41% to 85% (P < 0.001 vs. group I); in group III, from 9% to 18% (group II vs. group III, P < 0.001); and in group IV; from 36% to 38%. Moreover, aortic specimens of group II presented a statistically significant increase in MMP-2 and MMP-9 immunoexpression compared with other groups (I, III, IV) (P < 0.05 for all comparisons), with the exception of animals of group IV at the end of second week. Immunoreactivity of tissue inhibitor 1 of MMPs was not statistically different among groups II, III, and IV.

CONCLUSIONS

Simvastatin may prove clinically significant in suppressing the development and expansion of AAAs and, thereby, in reducing the risk of rupture and the need for repair.

Statin therapy reduces growth of abdominal aortic aneurysms

BACKGROUND

The aim of this study was to evaluate the influence of statins on the growth of small abdominal aortic aneurysms (AAAs).

METHODS

We retrospectively examined AAA diameter in 211 patients who had undergone serial imaging surveillance.

RESULTS

Patients treated with and without statins were similar regarding age, initial aneurysm size, diagnosis of diabetes and hypertension, and smoking history. Patients receiving statins had a decreased aneurysm growth rate compared with those patients not receiving statins (0.9 mm/y [interquartile range, -1.0 to +1.0] vs 3.2 mm/y [interquartile range, 2.0-4.9], P < 0.0001). This difference in the rate of growth was maintained after adjusting for potential confounding factors.

CONCLUSIONS

To date, this is the one of the largest retrospective studies demonstrating an association between statin use and decreased growth rate of AAA.

Neuropsychiatric symptoms in patients with aortic aneurysms

Background

Emerging evidence suggests that vascular disease confers vulnerability to a late-onset of depressive illness and the impairment of specific cognitive functions, most notably in the domains of memory storage and retrieval. Lower limb athero-thrombosis and abdominal aortic aneurysm (AAA) have both been previously associated with neuropsychiatric symptoms possibly due to associated intracerebral vascular disease or systemic inflammation, hence suggesting that these illnesses may be regarded as models to investigate the vascular genesis of neuropsychiatric symptoms. The aim of this study was to compare neuropsychiatric symptoms such as depression, anxiety and a variety of cognitive domains in patients who had symptoms of peripheral athero-thrombosis (intermittent claudication) and those who had an asymptomatic abdominal aortic aneurysm AAA.

Methodology/Principal Findings

In a cross-sectional study, 26 participants with either intermittent claudication or AAA were assessed using a detailed neuropsychiatric assessment battery for various cognitive domains and depression and anxiety symptoms (Hamilton Depression and Anxiety Scales). Student t test and linear regression analyses were applied to compare neuropsychiatric symptoms between patient groups. AAA participants showed greater levels of cognitive impairment in the domains of immediate and delayed memory as compared to patients who had intermittent claudication. Cognitive dysfunction was best predicted by increasing aortic diameter. CRP was positively related to AAA diameter, but not to cognitive function. AAA and aortic diameter in particular were associated with cognitive dysfunction in this study.

Conclusions/Significance

AAA patients are at a higher risk for cognitive impairment than intermittent claudication patients. Validation of this finding is required in a larger study, but if confirmed could suggest that systemic factors peculiar to AAA may impact on cognitive function.

Serum secreted phospholipase A2 is associated with abdominal aortic aneurysm presence but not progression

OBJECTIVE

Secretory phospholipase A(2) (sPLA(2)) has been implicated in rodent models of abdominal aortic aneurysm (AAA). The aim of this study was to assess whether serum sPLA(2) activity was associated with AAA presence and progression.

METHODS

Serum sPLA(2) activity was measured using a fluorometric assay in 1002 men of whom 310 had an AAA. 272 of the men had repeat ultrasound surveillance of their AAA for a median of 5.5 years. The association of sPLA(2) activity with AAA was assessed using multiple regression analysis to adjust for other risk factors.

RESULTS

Median serum sPLA(2) activity was 21.67 in men with AAA and 18.32 U/ml in men without AAA, p<0.001. Men with sPLA(2) activity ≥ median (19.20 U/ml) had a 1.40-fold (95% CI 1.04-1.87, p=0.027) increased prevalence of AAA independent of other risk factors. Serum sPLA(2) activity was not associated with AAA growth.

CONCLUSION

Serum sPLA(2) activity is elevated in men with small AAAs but is not associated with AAA progression.

Pathophysiology and epidemiology of abdominal aortic aneurysms

Abdominal aortic aneurysms (AAAs) are found in up to 8% of men aged >65 years, yet usually remain asymptomatic until they rupture. Rupture of an AAA and its associated catastrophic physiological insult carries overall mortality in excess of 80%, and 2% of all deaths are AAA-related. Pathologically, AAAs are associated with inflammation, smooth muscle cell apoptosis, and matrix degradation. Once thought to be a consequence of advanced atherosclerosis, accruing evidence indicates that AAAs are a focal representation of a systemic disease of the vasculature. Risk factors for AAAs include increasing age, male sex, smoking, and low HDL-cholesterol levels. Familial associations exist and although susceptibility genes have been described on the basis of candidate-gene studies, robust genetic studies have failed to discover causative gene mutations. The surgical management of AAAs has been revolutionized by minimally invasive endovascular repair. Ongoing randomized trials will establish whether endovascular repair confers a survival advantage over open surgery for patients with a ruptured AAA. In many countries, centralization of vascular surgical services has largely been driven by the improved outcomes of elective aneurysm surgery in specialized centers, the widespread adoption of endovascular techniques, and the introduction of screening programs.

Angiopoietins, abdominal aortic aneurysm and atherosclerosis

Abdominal aortic aneurysm (AAA) and atherosclerosis are common causes of mortality and morbidity in an aging population. Angiogenesis is believed to contribute to the development and progression of these diseases. Angiopoietins (angpts) are known to be important regulators of angiogenesis. Angpts can also influence inflammation and have been shown to possess both pro-atherosclerotic and atheroprotective effects. This review explores the potential roles that the angpts play in the development and progression of AAA and atherosclerosis.