Abdominal Aortic Aneurysms and Risk Factors for Adverse Events

CT analysis of aortic calcifications to predict abdominal aortic aneurysm rupture

BACKGROUND

Abdominal aortic aneurysm (AAA) rupture prediction based on sex and diameter could be improved. The goal was to assess whether aortic calcification distribution could better predict AAA rupture through machine learning and LASSO regression.

METHODOLOGY

In this retrospective study, 80 patients treated for a ruptured AAA between January 2001 and August 2018 were matched with 80 non-ruptured patients based on maximal AAA diameter, age, and sex. Calcification volume and dispersion, morphologic, and clinical variables were compared between both groups using a univariable analysis with p = 0.05 and multivariable analysis through machine learning and LASSO regression. We used AUC for machine learning and odds ratios for regression to measure performance.

RESULTS

Mean age of patients was 74.0 ± 8.4 years and 89% were men. AAA diameters were equivalent in both groups (80.9 ± 17.5 vs 79.0 ± 17.3 mm, p = 0.505). Ruptured aneurysms contained a smaller number of calcification aggregates (18.0 ± 17.9 vs 25.6 ± 18.9, p = 0.010) and were less likely to have a proximal neck (45.0% vs 76.3%, p < 0.001). In the machine learning analysis, 5 variables were associated to AAA rupture: proximal neck, antiplatelet use, calcification number, Euclidian distance between calcifications, and standard deviation of the Euclidian distance. A follow-up LASSO regression was concomitant with the findings of the machine learning analysis regarding calcification dispersion but discordant on calcification number.

CONCLUSION

There might be more to AAA calcifications that what is known in the present literature. We need larger prospective studies to investigate if indeed, calcification dispersion affects rupture risk.

CLINICAL RELEVANCE STATEMENT

Ruptured aneurysms are possibly more likely to have their calcification volume concentrated in a smaller geographical area.

KEY POINTS

• Abdominal aortic aneurysm (AAA) rupture prediction based on sex and diameter could be improved. • For a given calcification volume, AAAs with well-distributed calcification clusters could be less likely to rupture. • A machine learning model including AAA calcifications better predicts rupture compared to a model based solely on maximal diameter and sex alone, although it might be prone to overfitting.

Identification and Evaluation of Blood-Based Biomarkers for Abdominal Aortic Aneurysm

INTRODUCTION

Blood-based biomarkers for abdominal aortic aneurysm (AAA) have been studied individually; however, we considered a panel of proteins to investigate AAA prognosis and its potential to improve predictive accuracy.

MATERIALS AND METHODS

Using a prospectively recruited cohort of patients with/without AAA (n = 452), we conducted a prognostic study to develop a model that accurately predicts AAA outcomes using clinical features and circulating biomarker levels. Serum concentrations of 9 biomarkers were measured at baseline, and the cohort was followed for 2 years. The primary outcome was major adverse aortic event (MAAE; composite of rapid AAA expansion [>0.5 cm/6 months or >1 cm/12 months], AAA intervention, or AAA rupture). Using 10-fold cross-validation, we trained a random forest model to predict 2 year MAAE using (1) clinical characteristics, (2) biomarkers, and (3) clinical characteristics and biomarkers.

RESULTS

Two-year MAAE occurred in 114 (25%) patients. Two proteins were significantly elevated in patients with AAA compared with those without AAA (angiopoietin-2 and aggrecan), composing the protein panel. For predicting 2 year MAAE, our random forest model achieved area under the receiver operating characteristic curve (AUROC) 0.74 using clinical features alone, and the addition of the 2-protein panel improved performance to AUROC 0.86.

CONCLUSIONS

Using a combination of clinical/biomarker data, we developed a model that accurately predicts 2 year MAAE.

Integrated analysis of bulk RNA-seq and single-cell RNA-seq reveals the function of pyrocytosis in the pathogenesis of abdominal aortic aneurysm

Pyrocytosis is involved in the development of abdominal aortic aneurysm (AAA), we explored the pyrocytosis-related hub genes in AAA and conducted a diagnostic model based on the pyrocytosis-related genes score (PRGs). A total of 2 bulk RNA-seq (GSE57691 and GSE47472) datasets and pyrocytosis-related genes were integrated to obtain 24 pyrocytosis-related different expression genes (DEGs). The LASSO Cox regression analysis was conducted to filter out 7 genes and further establish the nomogram signature based on the PRGs that exhibited a good diagnosis value. Weighted gene co-expression network analysis (WGCNA) established 14 gene modules and further identified 6 hub genes which were involved in the regulatory process of pyrocytosis in AAA. At the single cell level, we further identified 3 immune cells were highly associated with the pyrocytosis process in AAA. Finally, the cell-cell communication demonstrated that fibroblasts and endothelial cells and myeloid cells maintained close communications. Here, we identified the dysfunctional expressed pyrocytosis-related genes and immune cells in AAA, which provide a comprehensive understanding of the pathogenesis of AAA.

The Global and Regional Prevalence of Abdominal Aortic Aneurysms: A Systematic Review and Modeling Analysis

OBJECTIVE

To estimate the global and regional prevalence and cases of abdominal aortic aneurysms (AAAs) in 2019 and to evaluate major associated factors.

BACKGROUND

Understanding the global prevalence of AAA is essential for optimizing health services and reducing mortality from reputed AAA.

METHODS

PubMed, MEDLINE, and Embase were searched for articles published until October 11, 2021. Population-based studies that reported AAA prevalence in the general population, defined AAA as an aortic diameter of 30 mm or greater with ultrasonography or computed tomography. A multilevel mixed-effects meta-regression approach was used to establish the relation between age and AAA prevalence for high-demographic sociodemographic index and low-and middle-sociodemographic index countries. Odds ratios of AAA associated factors were pooled using a random-effects method.

RESULTS

We retained 54 articles across 19 countries. The global prevalence of AAA among persons aged 30 to 79 years was 0.92% (95% CI, 0.65-1.30), translating to a total of 35.12 million (95% CI, 24.94-49.80) AAA cases in 2019. Smoking, male sex, family history of AAA, advanced age, hypertension, hypercholesterolemia, obesity, cardiovascular disease, cerebrovascular disease, claudication, peripheral artery disease, pulmonary disease, and renal disease were associated with AAA. In 2019, the Western Pacific region had the highest AAA prevalence at 1.31% (95% CI, 0.94-1.85), whereas the African region had the lowest prevalence at 0.33% (95% CI, 0.23-0.48).

CONCLUSIONS

A substantial proportion of people are affected by AAA. There is a need to optimize epidemiological studies to promptly respond to at-risk and identified cases to improve outcomes.

The role of phosphoinositide 3-kinases in immune-inflammatory responses: potential therapeutic targets for abdominal aortic aneurysm

The pathogenesis of abdominal aortic aneurysm (AAA) includes inflammatory responses, matrix metalloproteinases (MMPs) degradation, VSMC apoptosis, oxidative stress, and angiogenesis, among which the inflammatory response plays a key role. At present, surgery is the only curing treatment, and no effective drug can delay AAA progression in clinical practice. Therefore, searching for a signaling pathway related to the immune-inflammatory response is an essential direction for developing drugs targeting AAA. Recent studies have confirmed that the PI3K family plays an important role in many inflammatory diseases and is involved in regulating various cellular functions, especially in the immune-inflammatory response. This review focuses on the role of each isoform of PI3K in each stage of AAA immune-inflammatory response, making available explorations for a deeper understanding of the mechanism of inflammation and immune response during the formation and development of AAA.

miRNA Regulatory Networks Associated with Peripheral Vascular Diseases

A growing body of evidence indicates a crucial role of miRNA regulatory function in a variety of mechanisms that contribute to the development of diseases. In our previous work, alterations in miRNA expression levels and targeted genes were shown in peripheral blood mononuclear cells (PBMCs) from patients with lower extremity artery disease (LEAD), abdominal aortic aneurysm (AAA), and chronic venous disease (CVD) in comparison with healthy controls. In this paper, previously obtained miRNA expression profiles were compared between the LEAD, AAA, and CVD groups to find either similarities or differences within the studied diseases. Differentially expressed miRNAs were identified using the DESeq2 method implemented in the R programming software. Pairwise comparisons (LEAD vs. AAA, LEAD vs. CVD, and AAA vs. CVD) were performed and revealed 10, 8, and 17 differentially expressed miRNA transcripts, respectively. The functional analysis of the obtained miRNAs was conducted using the miRNet 2.0 online tool and disclosed associations with inflammation and cellular differentiation, motility, and death. The miRNet 2.0 tool was also used to identify regulatory interactions between dysregulated miRNAs and target genes in patients with LEAD, AAA, and CVD. The presented research provides new information about similarities and differences in the miRNA-dependent regulatory mechanisms involved in the pathogenesis of LEAD, AAA, and CVD.

A Social Network Analysis Approach to COVID-19 Community Detection Techniques

Machine learning techniques facilitate efficient analysis of complex networks, and can be used to discover communities. This study aimed use such approaches to raise awareness of the COVID-19. In this regard, social network analysis describes the clustering and classification processes for detecting communities. The background of this paper analyzed the geographical distribution of Tambaram, Chennai, and its public health care units. This study assessed the spatial distribution and presence of spatiotemporal clustering of public health care units in different geographical settings over four months in the Tambaram zone. To partition a homophily synthetic network of 100 nodes into clusters, an empirical evaluation of two search strategies was conducted for all IDs centrality of linkage is same. First, we analyzed the spatial information between the nodes for segmenting the sparse graph of the groups. Bipartite The structure of the sociograms 1–50 and 51–100 was taken into account while segmentation and divide them is based on the clustering coefficient values. The result of the cohesive block yielded 5.86 density values for cluster two, which received a percentage of 74.2. This research objective indicates that sub-communities have better access to influence, which might be leveraged to appropriately share information with the public could be used in the sharing of information accurately with the public.

Beliefs about Pain Control in Patients after Abdominal Aortic Aneurysm Surgery-A Preliminary Study

Introduction: Pain-control beliefs significantly influence the perception of disease and, therefore, may influence the treatment outcomes of surgical patients. The sense of control is related to the sense of agency and the ability to influence one’s own life and environment. This construct may be external or internal. The belief that pain control depends on internal or external factors can depend on many variables. This may be influenced by socio-demographic and clinical characteristics, as well as the source and cause of pain. The aim of the study was the assessment of the relationship between the intensity of postoperative pain and beliefs about pain control in patients after AAA surgery and assessment of the relationship between socio-demographic and clinical variables and beliefs about pain control in patients after AAA surgery. Materials and Methods: The research material consisted of 42 patients aged 57 to 85, hospitalized at the Department of Cardiac Surgery and Vascular Surgery of the University Clinical Center in Gdańsk. The research was conducted from March to September 2020. The study uses a survey technique based on a standardized research tool: the Polish version of the BPCQ (The Beliefs about Pain Control Questionnaire), the NRS (Numerical Rating Scale), and the author’s own questionnaire that allows for the collection of socio-demographic data. Results: The highest intensity of pain was observed in subjects with ruptured AAA H (2) = 6.19; p < 0.05 and subjects who underwent classic surgery Z = −2.95; p < 0.05 (non-parametric Mann−Whitney U test). Subjects with ruptured aneurysms are less convinced about the influence of internal factors on pain control H (2) = 5.26; p < 0.05. The respondents’ conviction about the influence of doctors on pain control increased together with their age, rHO = 0.38, p < 0.05. Conclusion: Pain intensity after surgery did not significantly correlate with beliefs about pain control. Patients with ruptured AAA are less convinced about the influence of internal factors on pain control. With age, patients have more confidence in their doctors than in themselves to control their pain.

The Impact of Abdominal Aortic Aneurysm on Cardiovascular Diseases

Cardiovascular diseases (CVDs) including myocardial infarction (MI) and stroke are often diagnosed in patients with abdominal aortic aneurysm (AAA). However, little has been reported regarding the incidence.Patients with AAA were selected from the National Health Insurance system in South Korea between 2009 and 2015. A total of 10,822 participants with a new diagnosis of AAA were included. Propensity score matching by age and sex with patients in whom AAA was not diagnosed was used to select the control group of 32,466 participants. Primary endpoints included the diagnosis of CVD and death. Cox proportional hazard models were used to compare the risk of disease incidence.The incidence of CVD was 16.573 per 1,000 person-years in the AAA group, which was higher than that of the control group's 9.30 per 1,000 person-years. The incidence of MI (hazard ratio [HR], 1.7; 95% confidence interval [CI], 1.479-1.953), stroke (HR, 1.629; 95% CI, 1.443-1.839), and CVD (HR, 1.672; 95% CI, 1.522-1.835) was significantly higher in patients with AAA. Mortality rate was also elevated in the AAA group (HR, 2.544; 95% CI, 2.377-2.722).The incidence of CVD was significantly more frequent in patients with AAA. The AAA group had consistently higher risks regarding CVD and mortality than the control group.

Osteopontin N-Terminal Function in an Abdominal Aortic Aneurysm From Apolipoprotein E-Deficient Mice

The cleavage of osteopontin (OPN) by thrombin results in an N-terminal fragment (OPN-N), which exposes a cryptic integrin-binding motif that promotes the adherence of cells, and plays a proinflammatory role. However, the effect of OPN-N on abdominal aortic aneurysm (AAA) remains unknown. The aim of this study was to investigate the expression of OPN-N in aortic tissue samples obtained from patients, who underwent acute aortic dissection (AD), and normal aorta, effect of OPN-N on angiotensin (Ang) II-induced AAA in mice, and relationship between OPN-N and pyroptosis-related inflammatory factors in vitro. Hematoxylin and eosin staining was conducted to detect histological changes. Next, we detected the expression of the OPN-N protein. Additionally, ApoE−/− mice were divided into four groups: control, control + M5Ab (to block the OPN-N function in mice), Ang II, and Ang II + M5Ab. All mice were euthanized after a 28-day infusion and whole aortas, including thoracic and abdominal aortas, were collected for morphological and histological analysis of the AAA. The OPN-N protein expression was higher in patients with AD than in normal individuals, while histological changes in the aortas of Ang II mice were suppressed in Ang II + M5Ab mice. The expression of OPN-N, NOD-, LRR-, and pyrin domain-containing protein 3, pro-Caspase-1, ASC, Gasdermin-d, interleukin (IL)-18, IL-1β, matrix metalloproteinase (MMP) 2, and MMP9 was lower in the Ang II + M5Ab group than in the Ang II group. The gene expression of monocyte chemoattractant protein-1, IL-6, and tumor necrosis factor-α was suppressed in the aortic tissues of the Ang II + M5Ab group compared with the Ang II group. Moreover, the expression of α-smooth muscle actin was lower in the Ang II group than in the Ang II + M5Ab group. In vitro results showed that the increase in the expression of pyroptosis-related inflammatory factors induced by OPN was mediated through the nuclear factor (NF)-κB pathway. In conclusion, OPN-N promotes AAA by increasing the expression of pyroptosis-related inflammatory factors through the NF-κB pathway, inflammation, and extracellular matrix degradation. These results highlight the potential of OPN-N as a new therapeutic target to prevent AAA expansion.

Circulating Biomarkers for the Prediction of Abdominal Aortic Aneurysm Growth

BACKGROUND

Abdominal aortic aneurysm represents a distinct group of vascular lesions, in terms of surveillance and treatment. Screening and follow-up of patients via duplex ultrasound has been well established and proposed by current guidelines. However, serum circulating biomarkers could earn a position in individualized patient surveillance, especially in cases of aggressive AAA growth rates. A systematic review was conducted to assess the correlation of AAA expansion rates with serum circulating biomarkers.

METHODS

A data search of English medical literature was conducted, using PubMed, EMBASE, and CENTRAL, until 7 March 2021, in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analysis statement (PRISMA) guidelines. Studies reporting on humans, on abdominal aortic aneurysm growth rates and on serum circulating biomarkers were included. No statistical analysis was conducted.

RESULTS

A total of 25 studies with 4753 patients were included. Studies were divided in two broad categories: Those reporting on clinically applicable (8 studies) and those reporting on experimental (17 studies) biomarkers. Twenty-three out of 25 studies used duplex ultrasound (DUS) for following patients. Amongst clinically applicable biomarkers, D-dimers, LDL-C, HDL-C, TC, ApoB, and HbA1c were found to bear the most significant association with AAA growth rates. In terms of the experimental biomarkers, PIIINP, osteopontin, tPA, osteopontin, haptoglobin polymorphisms, insulin-like growth factor I, thioredoxin, neutrophil extracellular traps (NETs), and genetic factors, as polymorphisms and microRNAs were positively correlated with increased AAA expansion rates.

CONCLUSION

In the presence of future robust data, specific serum biomarkers could potentially form the basis of an individualized surveillance strategy of patients presenting with increased AAA growth rates.

Identification of Transcriptomic Differences between Lower Extremities Arterial Disease, Abdominal Aortic Aneurysm and Chronic Venous Disease in Peripheral Blood Mononuclear Cells Specimens

Several human tissues are investigated in studies of molecular biomarkers associated with diseases development. Special attention is focused on the blood and its components due to combining abundant information about systemic responses to pathological processes as well as high accessibility. In the current study, transcriptome profiles of peripheral blood mononuclear cells (PBMCs) were used to compare differentially expressed genes between patients with lower extremities arterial disease (LEAD), abdominal aortic aneurysm (AAA) and chronic venous disease (CVD). Gene expression patterns were generated using the Ion S5XL next-generation sequencing platform and were analyzed using DESeq2 and UVE-PLS methods implemented in R programming software. In direct pairwise analysis, 21, 58 and 10 differentially expressed genes were selected from the comparison of LEAD vs. AAA, LEAD vs. CVD and AAA vs. CVD patient groups, respectively. Relationships between expression of dysregulated genes and age, body mass index, creatinine levels, hypertension and medication were identified using Spearman rank correlation test and two-sided Mann-Whitney U test. The functional analysis, performed using DAVID website tool, provides potential implications of selected genes in pathological processes underlying diseases studied. Presented research provides new insight into differences of pathogenesis in LEAD, AAA and CVD, and selected genes could be considered as potential candidates for biomarkers useful in diagnosis and differentiation of studied diseases.

Trends in abdominal aortic aneurysm-related mortality in Brazil, 2000-2016: a multiple-cause-of-death study

OBJECTIVES

Remarkable changes in the epidemiology of abdominal aortic aneurysm (AAA) have occurred in many countries during last few decades, which have also affected Brazilian mortality concurrently. This study aimed to investigate mortality trends related to AAA mortality in Brazil from 2000 to 2016.

METHODS

Annual AAA mortality data was extracted from the public databases of the Mortality Information System, and processed by the Multiple Cause Tabulator.

RESULTS

In Brazil, 2000 through 2016, AAA occurred in 69,513 overall deaths; in 79.6% as underlying and in 20.4% as an associated cause of death, corresponding to rates respectively of 2.45, 1.95 and 0.50 deaths per 100,000 population; 65.4% male and 34.6% female; 60.6% in the Southeast region. The mean ages at death were 71.141 years overall, and 70.385 years and 72.573 years for men and women, respectively. Ruptured AAA occurred in 64.3% of the deaths where AAA was an underlying cause, and in 18.0% of the deaths where AAA was an associated cause. The standardized rates increased during 2000-2008, followed by a decrease during 2008-2016, resulting in an average annual percent change decline of -0.2 (confidence interval [CI], -0.5 to 0.2) for the entire 2000-2016 period. As associated causes, shock (39.2%), hemorrhages (33.0%), and hypertensive diseases (26.7%) prevailed with ruptured aneurysms, while hypertensive diseases (29.4%) were associated with unruptured aneurysms. A significant seasonal variation, highest during autumn and followed by in winter, was observed in the overall ruptured and unruptured AAA deaths.

CONCLUSIONS

This study highlights the need to accurately document epidemiologic trends related to AAA in Brazil. We demonstrate the burden of AAA on mortality in older individuals, and our results may assist with effective planning of mortality prevention and control in patients with AAA.

ACR Appropriateness Criteria® Abdominal Aortic Aneurysm Follow-up (Without Repair)

Abdominal aortic aneurysm (AAA) is defined as aneurysmal dilation of the abdominal aorta to 3 cm or greater. A high degree of morbidity and mortality is associated with AAA rupture, and imaging surveillance plays an essential role in mitigating the risk of rupture. Aneurysm size and growth rate are factors associated with the risk of rupture, thus surveillance imaging studies must be accurate and reproducible to characterize aneurysm size. Ultrasound, CT angiography, and MR angiography provide an accurate and reproducible assessment of size, while radiographs and aortography provide limited evaluation. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Dysregulation of microRNA Modulatory Network in Abdominal Aortic Aneurysm

Abdominal artery aneurysm (AAA) refers to abdominal aortic dilatation of 3 cm or greater. AAA is frequently underdiagnosed due to often asymptomatic character of the disease, leading to elevated mortality due to aneurysm rupture. MiRNA constitute a pool of small RNAs controlling gene expression and is involved in many pathologic conditions in human. Targeted panel detecting altered expression of miRNA and genes involved in AAA would improve early diagnosis of this disease. In the presented study, we selected and analyzed miRNA and gene expression signatures in AAA patients. Next, generation sequencing was applied to obtain miRNA and gene-wide expression profiles from peripheral blood mononuclear cells in individuals with AAA and healthy controls. Differential expression analysis was performed using DESeq2 and uninformative variable elimination by partial least squares (UVE-PLS) methods. A total of 31 miRNAs and 51 genes were selected as the most promising biomarkers of AAA. Receiver operating characteristics (ROC) analysis showed good diagnostic ability of proposed biomarkers. Genes regulated by selected miRNAs were determined in silico and associated with functional terms closely related to cardiovascular and neurological diseases. Proposed biomarkers may be used for new diagnostic and therapeutic approaches in management of AAA. The findings will also contribute to the pool of knowledge about miRNA-dependent regulatory mechanisms involved in pathology of that disease.

AEBP1 Promotes the Occurrence and Development of Abdominal Aortic Aneurysm by Modulating Inflammation via the NF-κB Pathway

AIM

Inflammation plays a significant role in the pathogenesis of human abdominal aortic aneurysm (AAA). AEBP1 can promote activation of the NF-κB pathway, subsequently affecting the expression of NF-κB target genes, including inflammatory cytokines and matrix metalloproteinases (MMPs). Our objective was to examine the role of AEBP1 in the development of AAA and characterize the underlying mechanism.

METHODS

ITRAQ, RT-PCR, western blot, immunohistochemistry, and ELISA were used to compare different experimental groups with the controls and to determine the differentially expressed genes. We generated an AAA model using porcine pancreatic elastase in Sprague-Dawley rats and silenced their AEBP1 in vivo by adenoviruses injected intra-adventitially. We also silenced or overexpressed AEBP1 in human vascular smooth muscle cells in vitro in the presence and in the absence of NF-κB inhibitor BAY 11-7082.

RESULTS

Proteome iTRAQ revealed a high expression of AEBP1 in AAA patients, which was verified by qRT-PCR, western blot, immunohistochemistry, and ELISA. The mean expression level of AEBP1 in AAA patients was higher than that in controls. Along with AEBP1 upregulation, we also verified mis-activation of NF-κB in human AAA samples. The in vivo studies indicated that AEBP1 knockdown suppressed AAA progression. Finally, the in vitro studies illustrated that AEBP1 promotes activation of the NF-κB pathway, subsequently upregulating pro-inflammatory factors and MMPs.

CONCLUSIONS

Our results indicate a role of AEBP1 in the pathogenesis of AAA and provide a novel insight into how AEBP1 causes the development of AAA by activating the NF-κB pathway.

The Seed Coat Extract of Black Soybean Decreases Nicotine-Induced Vascular Fiber Degradation by Suppressing Matrix Metalloproteinase 2 Expression

Abdominal aortic aneurysm (AAA) is a vascular disease characterized by weakening of vascular walls and progressive dilation of the abdominal aorta. Nicotine, the main component of tobacco, is reportedly associated with the development and rupture of AAA. It is desirable to attenuate the destructive effect of nicotine on vascular walls, using dietary food components. However, effective methods for preventing AAA progression using dietary food components remain unestablished. This study focuses on proanthocyanidins, well known for their potent antioxidant activity. We speculated that proanthocyanidins can suppress nicotine-induced weakening of vascular walls. To estimate the effect of black soybean seed coat extract (BSSCE), rich in proanthocyanidins, on nicotine-induced weakening of the aortic wall, mice were divided into four groups: the control diet and distilled water group (named C), BSSCE solution diet and distilled water group (named B), control diet and 0.5 mg/mL nicotine solution group (named CN), and BSSCE solution diet and 0.5 mg/mL nicotine solution group (named BN). Nicotine-induced degradation of elastin and collagen fibers were significantly suppressed in BN group. The positive areas for matrix metalloproteinase (MMP)-2 and oxidative stress in BN group were significantly decreased compared to those in CN group. These results suggest that proanthocyanidins-rich BSSCE can prevent the weakening of the aortic wall via inhibiting MMP-2 upregulation.

Endothelium as a Potential Target for Treatment of Abdominal Aortic Aneurysm

Abdominal aortic aneurysm (AAA) was previously ascribed to weaken defective medial arterial/adventitial layers, for example, smooth muscle/fibroblast cells. Therefore, besides surgical repair, medications targeting the medial layer to strengthen the aortic wall are the most feasible treatment strategy for AAA. However, so far, it is unclear whether such drugs have any beneficial effect on AAA prognosis, rate of aneurysm growth, rupture, or survival. Notably, clinical studies have shown that AAA is highly associated with endothelial dysfunction in the aged population. Additionally, animal models of endothelial dysfunction and endothelial nitric oxide synthase (eNOS) uncoupling had a very high rate of AAA formation, indicating there is crucial involvement of the endothelium and a possible pharmacological solution targeting the endothelium in AAA treatment. Endothelial cells have been found to trigger vascular wall remodeling by releasing proteases, or recruiting macrophages along with other neutrophils, into the medial layer. Moreover, inflammation and oxidative stress of the arterial wall were induced by endothelial dysfunction. Interestingly, there is a paradoxical differential correlation between diabetes and aneurysm formation in retinal capillaries and the aorta. Deciphering the significance of such a difference may explain current unsuccessful AAA medications and offer a solution to this treatment challenge. It is now believed that AAA and atherosclerosis are two separate but related diseases, based on their different clinical patterns which have further complicated the puzzle. Therefore, a thorough investigation of the interaction between endothelium and medial/adventitial layer may provide us a better understanding and new perspective on AAA formation, especially after taking into account the importance of endothelium in the development of AAA. Moreover, a novel medication strategy replacing the currently used, but suboptimal treatments for AAA, could be informed with this analysis.

Chitosan-doxycycline hydrogel: An MMP inhibitor/sclerosing embolizing agent as a new approach to endoleak prevention and treatment after endovascular aneurysm repair

The success of endovascular repair of abdominal aortic aneurysms remains limited due to the development of endoleaks. Sac embolization has been proposed to manage endoleaks, but current embolizing materials are associated with frequent recurrence. An injectable agent that combines vascular occlusion and sclerosing properties has demonstrated promise for the treatment of endoleaks. Moreover, the inhibition of aneurysmal wall degradation via matrix metalloproteinases (MMPs) may further prevent aneurysm progression. Thus, an embolization agent that promotes occlusion, MMP inhibition and endothelial ablation was hypothesized to provide a multi-faceted approach for endoleak treatment. In this study, an injectable, occlusive chitosan (CH) hydrogel containing doxycycline (DOX)-a sclerosant and MMP inhibitor-was developed. Several CH-DOX hydrogel formulations were characterized for their mechanical and sclerosing properties, injectability, DOX release rate, and MMP inhibition. An optimized formulation was assessed for its short-term ability to occlude blood vessels in vivo. All formulations were injectable and gelled rapidly at body temperature. Only hydrogels prepared with 0.075M sodium bicarbonate and 0.08M phosphate buffer as the gelling agent presented sufficient mechanical properties to immediately impede physiological flow. DOX release from this gel was in a two-stage pattern: a burst release followed by a slow continuous release. Released DOX was bioactive and able to inhibit MMP-2 activity in human glioblastoma cells. Preliminary in vivo testing in pig renal arteries showed immediate and delayed embolization success of 96% and 86%, respectively. Altogether, CH-DOX hydrogels appear to be promising new multifunctional embolic agents for the treatment of endoleaks.

STATEMENT OF SIGNIFICANCE

An injectable embolizing chitosan hydrogel releasing doxycycline (DOX) was developed as the first multi-faceted approach for the occlusion of blood vessels. It combines occlusive properties with DOX sclerosing and MMP inhibition properties, respectively known to prevent recanalization process and to counteract the underlying pathophysiology of vessel wall degradation and aneurysm progression. After drug release, the biocompatible scaffold can be invaded by cells and slowly degrade. Local DOX delivery requires lower drug amount and decreases risks of side effects compared to systemic administration. This new gel could be used for the prevention or treatment of endoleaks after endovascular aneurysm repair, but also for the embolization of other blood vessels such as venous or vascular malformations.

A Simple Blood Test, Such as Complete Blood Count, Can Predict Calcification Grade of Abdominal Aortic Aneurysm

Objective

The pathogenesis of abdominal aortic aneurysm (AAA) is complex and different factors, including calcification, are linked to increased complications. This study was conducted in order to verify if classical risk factors for AAA and cell blood count parameter could help in the identification of calcification progression of the aneurysm.

Design

Risk factors were collected and cell blood count was performed in patients with AAA and patients were analyzed for the presence of aorta calcification using CT angiography.

Results

We found no association of calcification grade with risk factors for AAA but we found a strong association between MCV, MCH, and calcification grade. Instead, no association was found with the other parameter that we analyzed.

Conclusions

In this study, we demonstrate that biomarkers such as MCV and MCH could have potential important information about AAA calcification progression and could be useful to discriminate between those patients that should undergo a rapid imaging, thus allowing prompt initiation of treatment of suspicious patients that do not need imaging repetition.

Grape-seed Polyphenols Play a Protective Role in Elastase-induced Abdominal Aortic Aneurysm in Mice

Abdominal aortic aneurysm (AAA) is a kind of disease characterized by aortic dilation, whose pathogenesis is linked to inflammation. This study aimed to determine whether grape-seed polyphenols (GSP) has anti-AAA effects and what mechanism is involved, thus to find a way to prevent occurrence and inhibit expansion of small AAA. In our study, AAA was induced by incubating the abdominal aorta of the mice with elastase, and GSP was administrated to the mice by gavage at different doses beginning on the day of the AAA inducement. In in vivo experiments, 800 mg/kg GSP could significantly reduce the incidence of AAA, the dilatation of aorta and elastin degradation in media, and dramatically decrease macrophage infiltration and activation and expression of matrix metalloproteinase (MMP) -2 and MMP-9 in the aorta, compared to the AAA model group. Meanwhile, 400 mg/kg GSP could also but not completely inhibit the occurrence and development of AAA. In in vitro experiments, GSP dose-dependently inhibited mRNA expression of interleukin (IL)-1β, IL-6 and monocyte chemoattractant protein-1 (MCP-1), and significantly inhibited expression and activity of MMP-2 and MMP-9, thus prevented elastin from degradation. In conclusion, GSP showed great anti-AAA effects and its mechanisms were related to inhibition of inflammation.

Prediction of abdominal aortic aneurysm calcification by means of variation of high-sensitivity C-reactive protein

Objective

Abdominal aortic aneurysms are a major cause of death in developed countries, and thrombus and calcification of the aneurysm have been linked to increased complications. This study was conducted in order to identify the biochemical marker associated to the presence of intraluminal thrombus or calcification progression of the aneurysm.

Design

Several clinical laboratory parameters were measured in patients with abdominal aortic aneurysms, in particular those already demonstrated to be related to the pathology, such as lipoprotein (a), white blood cell count, fibrinogen and high-sensitivity C-reactive protein. Most of the patients were analysed for the presence of thrombus or aorta calcification using CT angiography.

Results

Unlike previous findings, we found no association between intraluminal thrombus formation and lipoprotein (a), but we evidenced that patients with lower grade of calcification tend to have higher plasma high-sensitivity C-reactive protein values compared with patients with a higher degree of calcification. Instead, no association was found with either white blood cell count or fibrinogen level.

Conclusions

This study suggests that high-sensitivity C-reactive protein is a useful biomarker to assess the evolution of calcification and could be used in triaging patients to identify those who should undergo a rapid imaging, thus allowing prompt initiation of treatment or rule-out suspicious patients from non-essential imaging repetition.