Inflammatory cell infiltrates, hypoxia, vascularization, pentraxin 3 and osteoprotegerin in abdominal aortic aneurysms - A quantitative histological study

Intervention effect of regulating GABA-A receptor activity on the formation of experimental abdominal aortic aneurysm in rats

Abdominal aortic aneurysm is a potentially fatal vascular inflammatory disease characterized by infiltration of various inflammatory cells.The GABA-A receptor is expressed in many inflammatory cells such as macrophages and T cells and has anti-inflammatory and antioxidant effects. Therefore, the GABA-A receptor may become a potential therapeutic target for abdominal aortic aneurysms. The purpose of this study was to investigate the effect of regulating the activity of the GABA-A receptor on the formation of experimental abdominal aortic aneurysm in rats. In this study, the abdominal aortic aneurysm model of rats was established by aorta intracavitary perfusion of elastase combined with aorta extracavitary infiltration of calcium chloride. GABA-A receptor agonist (topiramate) and antagonist (bicuculline) were used to treating the abdominal aortic aneurysm model rats, which were divided into sham operation group, model group, topiramate group, and bicuculline group(n = 10). Histopathology, immunohistochemistry, fluorescence quantitative PCR, Western blotting, ELISA and Gelatine zymogram were used to study. Regulation of GABA-A receptor activity can interfere with the development and severity of abdominal aortic aneurysms in rats. The GABA-A receptor agonist topiramate reduces the infiltration of inflammatory cells, particularly T cells, into the abdominal aortic wall, while also modulating the balance of Th1/Th2 cytokines in peripheral blood, leading to a significant reduction in inflammatory responses. Additionally, topiramate decreases the secretion of matrix metalloproteinases MMP2 and MMP9, thereby inhibiting extracellular matrix degradation and slowing the progression of aneurysms. In contrast, the GABA-A receptor antagonist bicuculline exacerbates inflammation and promotes aneurysm development. At the molecular level, the mechanisms of action of the GABA-A receptor agonist topiramate and the antagonist bicuculline may involve inhibition or activation of the p38 MAPK signaling pathway. Regulation of GABA-A receptor activity can effectively intervene in the occurrence and development of abdominal aortic aneurysms in rats.

GSDMB involvement in the pathogenesis of abdominal aortic aneurysm through regulation of macrophage non-canonical pyroptosis

Abdominal aortic aneurysm (AAA) is a dangerous condition affecting the aorta. Macrophage pyroptosis, phenotypic transformation, and apoptosis of aortic smooth muscle cells (ASMCs) are pivotal mechanisms in AAA pathogenesis. This study explores how Gasdermin B (GSDMB) regulates macrophage non-canonical pyroptosis and its impact on the phenotypic transformation and apoptosis of ASMCs, thereby unveiling the role of GSDMB in AAA pathogenesis. Immunofluorescence analysis was used to assess the expression levels and localization of GSDMB, cysteinyl aspartate-specific protease-4 (Caspase-4), and N-terminal of cleaved GSDMD (N-GSDMD) in AAA tissues. A cell model that mimics macrophage non-canonical pyroptosis was established by treating THP-1 cells with lipopolysaccharide (LPS). THP-1 cells with reduced or increased GSDMB were generated using small interfering RNA (siRNA) or plasmids. Co-culture experiments involving THP-1 cells and HASMCs were conducted to explore the impact of GSDMB on HASMCs. The mitochondrial reactive oxygen species (mtROS) scavenger Mito-TEMPO lowered mtROS levels in THP-1 cells. Our findings revealed that GSDMB was significantly upregulated in AAA macrophages, which was accompanied by robust non-canonical pyroptosis. THP-1 cells showed non-canonical pyroptosis in response to LPS, which was accompanied by an increase in GSDMB. Further research demonstrated that altering GSDMB, either by knockdown or overexpression, can affect macrophage non-canonical pyroptosis as well as the phenotypic transformation and apoptosis of HASMCs. LPS-induced non-canonical pyroptosis in THP-1 cells was associated with an increase in mtROS, whereas Mito-TEMPO effectively decreased non-canonical pyroptosis and the expression of GSDMB. These findings suggest that GSDMB plays a role in AAA macrophage non-canonical pyroptosis, which influences the phenotypic transformation and apoptosis of HASMCs. The mtROS-Dynamin-Related Protein 1 (Drp1) axis is likely to regulate the GSDMB-mediated non-canonical pyroptosis.

Nicotine induces vasa vasorum stenosis in the aortic wall

Abdominal aortic aneurysm (AAA) is a vascular disease that involves aortic wall dilation. Cigarette smoking is an established risk factor and rupture, and nicotine may be a major contributor to the onset of AAA. In humans the condition is associated with stenosis of the vasa vasorum (VV), which may be caused by nicotine. In this study, we evaluated the effects of nicotine on VV pathology. After 4 weeks of nicotine administration to rats using an osmotic pump, the VV patency rate in the nicotine administration group was significantly lower than that in the control group. The levels of Ki-67, a cell proliferation marker, were significantly increased in the regions containing VV in the nicotine group, as were hypoxia inducible factor-α levels. Collagen levels around VV were significantly lower in the nicotine group than in the controls. Our data suggest that nicotine can cause VV stenosis by inducing abnormal proliferation of smooth muscle cells in the VV. The increased risk of AAA development due to cigarette smoking may be partially explained by nicotine-induced VV denaturation and collagen fiber degradation.

Next-Generation Sequencing of microRNAs in Small Abdominal Aortic Aneurysms: MiR-24 as a Biomarker

BACKGROUND

Small abdominal aortic aneurysms (AAAs) are asymptomatic but can potentially lead to rupture if left undetected. To date, there is a lack of simple nonradiologic routine tests available for diagnosing AAAs. MicroRNAs (miRNAs) have been proven to be good-quality biomarkers in several diseases, including AAA.

METHODS

An attempt to identify a panel of circulating miRNAs with differential expression in AAAs via next-generation sequencing (NGS) was performed in serum samples: small AAAs (n = 3), large AAAs (n = 3), and controls (n = 3). For miR-24, validation with real-time polymerase chain reaction (PCR) was undertaken in a larger group (n = 80).

RESULTS

In the NGS study, 23 miRNAs were identified as differentially expressed (with statistical significance) in small AAAs in comparison with controls. Among them, miR-24 showed the largest upregulation with 23-fold change (log2FC 4.5, P = 0.024). For large AAAs compared with controls, and small AAAs compared with large AAAs, a panel of 33 and 131 miRNAs showed statistically significant differential expression, respectively. Based on the results of the NGS stage, a literature search was performed, and information regarding AAA pathogenesis, coronary artery disease, and peripheral arterial disease was documented where applicable: miR-24, miR-103, miR-193a, miR-486, miR-582, and miR-3663. Of these 6 miRNAs, miR-24 was chosen for further validation with real-time PCR. Additionally, in the NGS study analysis, 17 miRNAs were common between the small-large AAAs, small AAAs-controls, and large AAAs-controls comparisons: miR-7846, miR-3195, miR-486-2, miR-3194, miR-5589, miR-1538, miR-3178, miR-4771-1, miR-5695, miR-6504, miR-1908, miR-6823, miR-3159, miR-23a, miR-7853, miR-496, and miR-193a. Interestingly, in the validation stage with real-time PCR, miR-24 was found downregulated in small and large AAAs compared with controls (fold-changes: 0.27, P = 0.015 and 0.15, P = 0.005, respectively). No correlation was found between average Ct values, aneurysm diameter, and patients' age.

CONCLUSIONS

Our findings further highlight the importance of miR-24 as a potential biomarker as well as a therapeutic target for abdominal aneurysmal disease. Future research and validation of a panel of miRNAs for AAA would aid in diagnosis and discrimination between diseases with overlapping pathogeneses.

Hypoxia inducible factor 1-alpha in the pathogenesis of abdominal aortic aneurysms in vivo: A narrative review

Abdominal aortic aneurysms (AAAs) are relatively common, primarily among older men, and, in the case of rupture, are associated with high mortality. Although procedure-related morbidity and mortality have improved with the advent of endovascular repair, noninvasive treatment and improved assessment of AAA rupture risk should still be sought. Several cellular pathways seem contributory to the histopathologic changes that drive AAA growth and rupture. Hypoxia inducible factor 1-alpha (HIF-1α) is an oxygen-sensitive protein that accumulates in the cytoplasm under hypoxic conditions and regulates a wide array of downstream effectors to hypoxia. Examining the potential role of HIF-1α in the pathogenesis of AAAs is alluring, because local hypoxia is known to be present in the AAA vessel wall. A systematic scoping review was performed to review the current evidence regarding the role of HIF-1α in AAA disease in vivo. After screening, 17 studies were included in the analysis. Experimental animal studies and human studies show increased HIF-1α activity in AAA tissue compared with healthy aorta and a correlation of HIF-1α activity with key histopathologic features of AAA disease. In vivo HIF-1α inhibition in animals protects against AAA development and growth. One study reveals a positive correlation between HIF-1α-activating genetic polymorphisms and the risk of AAA disease in humans. The main findings suggest a causal role of HIF-1α in the pathogenesis of AAAs in vivo. Further research into the HIF-1α pathway in AAA disease might reveal clinically applicable pharmacologic targets or biomarkers relevant in the treatment and monitoring of AAA disease.

Analyzing the contribution of vasa vasorum in oxygenation of the aneurysmal wall: A computational study

The mechanisms of abdominal aortic aneurysm (AAA) formation and rupture are controversial in the literature. While the intraluminal thrombus (ILT) plays a crucial role in reducing oxygen flux to the tissue and therefore decreasing the aortic wall strength, other physiological parameters such as the vasa vasorum (VV) oxygen flow and its consumption contribute to altered oxygenation responses of the arterial tissue as well. The goal of this research is to analyse the importance of the aforementioned parameters on oxygen delivery to the aneurysmal wall in a patient-specific AAA. Numerical simulations of coupled blood flow and mass transport with varying levels of VV concentration and oxygen reaction rate coefficient are performed. The hypoperfusion of the adventitial VV and high oxygen consumption are observed to have critical effects on reducing aneurysmal tissue oxygen supply and can therefore exacerbate localized oxygen deprivation.

Histological mapping of healing of the small and large intestine – a quantitative study in a porcine model

BACKGROUND

Gastrointestinal anastomoses are performed in many patients every year. The pathogenesis of aberrant anastomotic healing and the causes of intestinal leakage are not fully understood. The present study gathered and critically evaluated histological quantitative data to deepen current knowledge of anastomotic healing in the small and large intestine and its complications and outline the options for further experimental in vivo research in large porcine animal models.

METHODS

Three groups of porcine intestinal anastomoses were compared: small intestine without defect (SI; n=7), small intestine with an additional defect (SID; n=8), and large intestine (LI; n=7). Multilevel sampling (2,112 micrographs) and stereological methods were used for histological quantification of proliferation (Ki-67 immunohistochemistry), neutrophil infiltration (myeloperoxidase staining), vascularity (von Willebrand factor) and type I and type III collagen formation (picrosirius red in polarized light) within the region of anastomosis compared to the region outside of anastomosis.

RESULTS

Quantitative histological evaluation revealed the following results. i) Proliferation, vascularity, and collagen, but not neutrophils, were more highly expressed within the anastomosis than outside of the anastomosis region. ii) Porcine large and small intestine were not interchangeable based on histological evaluation of surgical experiments. The presence or absence of an additional experimental defect strongly affected healing, but the healing seemed complete after 21 days. iii) The microscopic structure of small intestine segments was more affected by their proximity to the anastomosis than the structure of large intestine segments.

CONCLUSIONS

Histological quantification was more laborious than the previously used semiquantitative scoring system evaluating the healing rate of intestinal anastomoses, but it provided detailed maps of biological processes within individual intestine layers. The primary data collected in the study are open and available for power sample analyses to calculate the minimum numbers of samples justified in future experiments on porcine intestines. The porcine intestine is a promising animal model with translational potential for human surgery.

Tricaprin can prevent the development of AAA by attenuating aortic degeneration

Medical therapeutic options to prevent rupture of abdominal aortic aneurysm (AAA), a critical event, must be developed. Moreover, further understanding of the process of AAA development and rupture is crucial. Previous studies have revealed that aortic hypoperfusion can induce the development of AAA, and we successfully developed a hypoperfusion-induced AAA animal model. In this study, we examined the effects of medium-chain triglycerides (MCTs), tricaprylin (C8-TG) and tricaprin (C10-TG), on hypoperfusion-induced AAA rat model. We estimated the effects of MCTs on aortic pathologies, mechanical properties of the aorta, and development of AAA. C10-TG, but not C8-TG, significantly suppressed AAA development and completely prevented the rupture. We observed that C10-TG prevented the development and rupture of AAA, but not C8-TG. Additionally, regression of AAA diameter was observed in the C10-TG group. Pathological analysis revealed C10-TG improved the hypoperfusion-induced increase in hypoxia-inducible factor-1α levels, medial smooth muscle cells (SMCs) loss, degeneration of aortic elastin and collagen fibers, and loss of aortic wall elasticity. In addition, regression of the formed AAA was observed by administration of C10-TG after AAA formation. C10-TG administration after AAA formation improved degeneration of AAA wall including degradation of aortic elastin and collagen fibers, stenosis of vasa vasorum, and loss of medial SMCs. These data suggest C10-TG can prevent AAA by attenuating aortic hypoperfusion and degeneration. Considering the clinical safety of C10-TG, C10-TG can be a promising AAA drug candidate.

Lessons from Cardiac and Vascular Biopsies from Patients with and without Inflammatory Rheumatic Diseases

Feiring Heart Biopsy Study enables searching for potential pathogenetic mechanisms, therapeutic targets, and biomarkers through the assessment of clinical data and multiple blood and tissue samples from patients with and without inflammatory rheumatic diseases (IRDs), undergoing coronary artery bypass grafting. Some of our findings, for example, more inflammation (including the presence of immune cells and expression of proinflammatory cytokines) in vessels and the heart, and the presence of certain bacteria and autoantigens in vessels, could contribute to the increased risk of ischemia, aneurysms, and/or cardiac dysfunction in IRDs. Furthermore, some of the detected factors could be involved in the pathomechanisms of these conditions in general.

Markers of extracellular matrix remodeling and systemic inflammation in patients with heritable thoracic aortic diseases

Background

In approximately 20% of patients with thoracic aortic aneurysms or dissections a heritable thoracic aortic disease (HTAD) is suspected. Several monogenic connective tissue diseases imply high risk of aortic disease, including both non-syndromic and syndromic forms. There are some studies assessing inflammation and extracellular matrix remodeling in patients with non-hereditary aortic disease, but such studies in patients with hereditary diseases are scarce.

Aims

To quantify markers of extracellular matrix (ECM) and inflammation in patients with vascular connective tissue diseases versus healthy controls.

Methods

Patients with Loeys-Dietz syndrome (LDS, n = 12), Marfan syndrome (MFS, n = 11), and familial thoracic aortic aneurysm 6 (FTAA6, n = 9), i.e., actin alpha 2 (ACTA2) pathogenic variants, were recruited. Exome or genome sequencing was performed for genetic diagnosis. Several markers of inflammation and ECM remodeling were measured in plasma by enzyme immunoassays. Flow cytometry of T-cell subpopulations was performed on a subgroup of patients. For comparison, blood samples were drawn from 14 healthy controls.

Results

(i) All groups of HTAD patients had increased levels matrix metalloproteinase-9 (MMP-9) as compared with healthy controls, also in adjusted analyses, reflecting altered ECM remodeling. (ii) LDS patients had increased levels of pentraxin 3 (PTX3), reflecting systemic inflammation. (iii) LDS patients have increased levels of soluble CD25, a marker of T-cell activation.

Conclusion

Our data suggest that upregulated MMP-9, a matrix degrading enzyme, is a common feature of several subgroups of HTAD. In addition, LDS patients have increased levels of PTX3 reflecting systemic and in particular vascular inflammation.

Identification of MEDAG and SERPINE1 Related to Hypoxia in Abdominal Aortic Aneurysm Based on Weighted Gene Coexpression Network Analysis

Purpose: Abdominal aortic aneurysm (AAA) is a severe cardiovascular disease that often results in high mortality due to sudden rupture. This paper aims to explore potential molecular mechanisms and effective targeted therapies to prevent and delay AAA rupture. Methods: We downloaded two microarray datasets (GSE98278 and GSE17901) from the Gene Expression Omnibus (GEO) database. Differential analysis and single-sample gene set enrichment analysis (ssGSEA) of hypoxia scores were performed on 48 AAA patients in GSE98278. We identified hypoxia- and ruptured AAA-related gene modules using weighted gene coexpression network analysis (WGCNA). Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were performed using the R package clusterProfiler. For candidate genes, validation was conducted on the mouse dataset GSE17901. Finally, we predicted drug candidates associated with the hub genes using the HERB Chinese medicine database. Results: Eighty-two differentially expressed genes were screened in the ruptured and stable groups; 103 differentially expressed genes were identified between the high- and low-hypoxia groups; and WGCNA identified 58 differentially expressed genes. Finally, nine candidate genes were screened, including two hub genes (MEDAG and SERPINE1). We identified pathways such as cytokine-cytokine receptor interaction and T-helper 1-type immune response involved in AAA hypoxia and rupture. We predicted 93 traditional Chinese medicines (TCMs) associated with MEDAG and SERPINE1. Conclusion: We identified the hypoxic molecules MEDAG and SERPINE1 associated with AAA rupture. Our study provides an additional direction for the association between hypoxia and AAA rupture.

On vasa vasorum: A history of advances in understanding the vessels of vessels

The vasa vasorum are a vital microvascular network supporting the outer wall of larger blood vessels. Although these dynamic microvessels have been studied for centuries, the importance and impact of their functions in vascular health and disease are not yet fully realized. There is now rich knowledge regarding what local progenitor cell populations comprise and cohabitate with the vasa vasorum and how they might contribute to physiological and pathological changes in the network or its expansion via angiogenesis or vasculogenesis. Evidence of whether vasa vasorum remodeling incites or governs disease progression or is a consequence of cardiovascular pathologies remains limited. Recent advances in vasa vasorum imaging for understanding cardiovascular disease severity and pathophysiology open the door for theranostic opportunities. Approaches that strive to control angiogenesis and vasculogenesis potentiate mitigation of vasa vasorum-mediated contributions to cardiovascular diseases and emerging diseases involving the microcirculation.

The physiological and clinical importance of cardiorespiratory fitness in people with abdominal aortic aneurysm

New Findings

What is the topic of this review?

This review focuses on the physiological impact of abdominal aortic aneurysm (AAA) on cardiorespiratory fitness and the negative consequences of low fitness on clinical outcomes in AAA. We also discuss the efficacy of exercise training for improving cardiorespiratory fitness in AAA.

What advances does it highlight?

We demonstrate the negative impact of low fitness on disease progression and clinical outcomes in AAA. We highlight potential mechanistic determinants of low fitness in AAA and present evidence that exercise training can be an effective treatment strategy for improving cardiorespiratory fitness, postoperative mortality and disease progression.

Abstract

An abdominal aortic aneurysm (AAA) is an abnormal enlargement of the aorta, below the level of the renal arteries, where the aorta diameter increases by >50%. As an aneurysm increases in size, there is a progressive increase in the risk of rupture, which ranges from 25 to 40% for aneurysms >5.5 cm in diameter. People with AAA are also at a heightened risk of cardiovascular events and associated mortality. Cardiorespiratory fitness is impaired in people with AAA and is associated with poor (postoperative) clinical outcomes, including increased length of hospital stay and postoperative mortality after open surgical or endovascular AAA repair. Although cardiorespiratory fitness is a well‐recognized prognostic marker of cardiovascular health and mortality, it is not assessed routinely, nor is it included in current clinical practice guidelines for the management of people with AAA. In this review, we discuss the physiological impact of AAA on cardiorespiratory fitness, in addition to the consequences of low cardiorespiratory fitness on clinical outcomes in people with AAA. Finally, we summarize current evidence for the effect of exercise training interventions on cardiorespiratory fitness in people with AAA, including the associated improvements in postoperative mortality, AAA growth and cardiovascular risk. Based on this review, we propose that cardiorespiratory fitness should be considered as part of the routine risk assessment and monitoring of people with AAA and that targeting improvements in cardiorespiratory fitness with exercise training might represent a viable adjunct treatment strategy for reducing postoperative mortality and disease progression.

Genome-Wide Identification of Immune-Related Alternative Splicing and Splicing Regulators Involved in Abdominal Aortic Aneurysm

The molecular mechanism of AAA formation is still poorly understood and has not been fully elucidated. The study was designed to identify the immune-related genes, immune-RAS in AAA using bioinformatics methods. The GSE175683 datasets were downloaded from the GEO database. The DEseq2 software was used to identify differentially expressed genes (DEGs). SUVA pipeline was used to quantify AS events and RAS events. KOBAS 2.0 server was used to identify GO terms and KEGG pathways to sort out functional categories of DEGs. The CIBERSORT algorithm was used with the default parameter for estimating immune cell fractions. Nine samples from GSE175683 were used to construct the co-disturbed network between expression of SFs and splicing ratio of RAS events. PCA analysis was performed by R package factoextra to show the clustering of samples, and the pheatmap package in R was used to perform the clustering based on Euclidean distance. The results showed that there were 3,541 genes significantly differentially expressed, of which 177 immune-related genes were upregulated and 48 immune-related genes were downregulated between the WT and WTA group. Immune-RAS events were mainly alt5P and IR events, and about 60% of it was complex splicing events in AAA. The WT group and the WTA group can be clearly distinguished in the first principal component by using the splicing ratio of immune-RAS events. Two downregulated genes, Nr4a1 and Nr4a2, and eight upregulated genes, Adipor2, Akt2, Bcl3, Dhx58, Pparg, Ptgds, Sytl1, and Vegfa were identified among the immune-related genes with RAS and DEGs. Eighteen differentially expressed SFs were identified and displayed by heatmap. The proportion of different types of cells and ratio of the average ratio of different cells were quite different. Both M1 and M2 types of macrophages and plasma cells were upregulated, while M0 type was downregulated in AAA. The proportion of plasma cells in the WTA group had sharply increased. There is a correlation between SF expression and immune cells/immune-RAS. Sf3b1, a splicing factor with significantly different expression, was selected to bind on a mass of immune-related genes. In conclusion, our results showed that immune-related genes, immune-RAS, and SFs by genome-wide identification were involved in AAA.

Association of Aneurysm Tissue Neutrophil Mediator Levels with Intraluminal Thrombus Thickness in Patients with Abdominal Aortic Aneurysm

An intraluminal thrombus (ILT), which accumulates large numbers of neutrophils, plays a key role in abdominal aortic aneurysm (AAA) pathogenesis. This study aimed to compare levels of selected neutrophil inflammatory mediators in thick and thin ILT, plus adjacent AAA walls, to determine whether levels depend on ILT thickness. Neutrophil mediator levels were analysed by enzyme-linked immunosorbent assays in thick and thin segments of ILT, plus adjacent aneurysm wall sections, taken from one aneurysm sac each from 36 AAA patients. In aneurysmal walls covered by thick ILT, neutrophil elastase and TNF-a levels were significantly higher, as were concentrations of IL-6, in thick ILT compared to thin layers. Positive correlations of NGAL, MPO, and neutrophil elastase were observed between thick ILT and the adjacent wall and thin ILT and the adjacent wall, suggesting that these mediators probably infiltrate thick AAA compartments as well as thin. These observations might support the idea that neutrophil mediators and inflammatory cytokines differentially accumulate in AAA tissues according to ILT thickness. The increased levels of neutrophil mediators within thicker AAA segments might suggest the existence of an intensified proinflammatory state that in turn presumably might preferentially weaken the AAA wall at that region.

Biomarkers in EndoVascular Aneurysm Repair (EVAR) and Abdominal Aortic Aneurysm: Pathophysiology and Clinical Implications

Circulating biomarkers have been recently investigated among patients undergoing endovascular aortic aneurysm repair (EVAR) for abdominal aortic aneurysm (AAA). Considering the plethora of small descriptive studies reporting potential associations between biomarkers and clinical outcomes, this review aims to summarize the current literature considering both the treated disease (post EVAR) and the untreated disease (AAA before EVAR). All studies describing outcomes of tissue biomarkers in patients undergoing EVAR and in patients with AAA were included, and references were checked for additional sources. In the EVAR scenario, circulating interleukin-6 (IL-6) is a marker of inflammatory reaction which might predict postoperative morbidity; cystatin C is a promising early marker of post-procedural acute kidney injury; plasma matrix metalloproteinase-9 (MMP-9) concentration after 3 months from EVAR might help in detecting post-procedural endoleak. This review also summarizes the current gaps in knowledge and future direction of this field of research. Among markers used in patients with AAA, galectin and granzyme appear to be promising and should be carefully investigated even in the EVAR setting. Larger prospective trials are required to establish and evaluate prognostic models with highest values with these markers.

AAA Revisited: A Comprehensive Review of Risk Factors, Management, and Hallmarks of Pathogenesis

Despite declining incidence and mortality rates in many countries, the abdominal aortic aneurysm (AAA) continues to represent a life-threatening cardiovascular condition with an overall prevalence of about 2-3% in the industrialized world. While the risk of AAA development is considerably higher for men of advanced age with a history of smoking, screening programs serve to detect the often asymptomatic condition and prevent aortic rupture with an associated death rate of up to 80%. This review summarizes the current knowledge on identified risk factors, the multifactorial process of pathogenesis, as well as the latest advances in medical treatment and surgical repair to provide a perspective for AAA management.

Using virtual microscopy for the development of sampling strategies in quantitative histology and design-based stereology

Only a fraction of specimens under study are usually selected for quantification in histology. Multilevel sampling or tissue probes, slides and fields of view (FOVs) in the regions of interest (ROIs) are required. In general, all parts of the organs under study should be given the same probability to be taken into account; that is, the sampling should be unbiased on all levels. The objective of our study was to provide an overview of the use of virtual microscopy in the context of developing sampling strategies of FOVs for stereological quantification. We elaborated this idea on 18 examples from multiple fields of histology, including quantification of extracellular matrix and muscle tissue, quantification of organ and tumour microvessels and tumour-infiltrating lymphocytes, assessing osseointegration of bone implants, healing of intestine anastomoses and osteochondral defects, counting brain neurons, counting nuclei in vitro cell cultures and others. We provided practical implications for the most common situations, such as exhaustive sampling of ROIs, sampling ROIs of different sizes, sampling the same ROIs for multiple histological methods, sampling more ROIs with variable intensities or using various objectives, multistage sampling and virtual sampling. Recommendations were provided for pilot studies on systematic uniform random sampling of FOVs as a part of optimizing the efficiency of histological quantification to prevent over- or undersampling. We critically discussed the pros and cons of using virtual sections for sampling FOVs from whole scanned sections. Our review demonstrated that whole slide scans of histological sections facilitate the design of sampling strategies for quantitative histology.

Pentraxin 3 levels and correlation with disease severity in patients with acute rheumatic fever

Objectives

This study aims to investigate serum pentraxin 3 (PTX3) levels during acute episode of acute rheumatic fever (ARF) and their relationship with disease severity.

Patients and methods

The prospective study was conducted between January 2015 and December 2018 and included 52 ARF patients (22 girls, 30 boys, mean age 10.7±2.1 years; range, 5 to 16 years) experiencing an acute episode and 22 healthy children (13 girls, 9 boys, mean age 10.3±3.8 years; range, 5 to 16 years). ARF patients were classified into three groups based on the clinical course: isolated arthritis (n=17), mild carditis (n=19), and moderate/severe carditis (n=16). Blood samples were collected from all patients before treatment and from the healthy children in the control group to measure PTX3 levels. PTX3 was measured using sandwich enzyme-linked immunosorbent assay method.

Results

Plasma PTX3 levels were significantly higher in ARF group compared to the control group (4.7±5.2 and 1.2±1.7 ng/mL, p<0.001). Subgroup analysis of serum PTX3 levels in ARF patients with isolated arthritis, mild carditis, and moderate/severe carditis (3.2±3.1 ng/mL, 4.3±5 ng/mL, and 6.7±6.6 ng/mL, respectively) showed that serum PTX3 was significantly higher in the moderate/severe carditis group compared to the other groups (p<0.05). Analysis of echocardiographic data showed that serum PTX3 was positively correlated with left ventricular end-diastolic diameter, left atrial diameters, and mitral A velocity and negatively correlated with E/A ratio (p<0.05; r=0.231, 0.402, 0.562, -0.586, respectively).

Conclusion

High PTX3 level during an acute episode of ARF may help predict the clinical course and the severity of accompanying carditis. However, prospective studies with larger sample sizes are needed.

Use of MALDI Mass Spectrometry Imaging to Identify Proteomic Signatures in Aortic Aneurysms after Endovascular Repair

Endovascular repair (EVAR) has become the standard procedure in treating thoracic (TAA) or abdominal aortic aneurysms (AAA). Not entirely free of complications, a persisting perfusion of the aneurysm after EVAR, called Endoleak (EL), leads to reintervention and risk of secondary rupture. How the aortic wall responds to the implantation of a stentgraft and EL is mostly uncertain. We present a pilot study to identify peptide signatures and gain new insights in pathophysiological alterations of the aortic wall after EVAR using matrix-assisted laser desorption or ionization mass spectrometry imaging (MALDI-MSI). In course of or accompanying an open aortic repair, tissue sections from 15 patients (TAA = 5, AAA = 5, EVAR = 5) were collected. Regions of interest (tunica media and tunica adventitia) were defined and univariate (receiver operating characteristic analysis) statistical analysis for subgroup comparison was used. This proof-of-concept study demonstrates that MALDI-MSI is feasible to identify discriminatory peptide signatures separating TAA, AAA and EVAR. Decreased intensity distributions for actin, tropomyosin, and troponin after EVAR suggest impaired contractility in vascular smooth muscle cells. Furthermore, inability to provide energy caused by impaired respiratory chain function and continuous degradation of extracellular matrix components (collagen) might support aortic wall destabilization. In case of EL after EVAR, this mechanism may result in a weakened aortic wall with lacking ability to react on reinstating pulsatile blood flow.

Circular RNA Expression: Its Potential Regulation and Function in Abdominal Aortic Aneurysms

Abdominal aortic aneurysms (AAAs) have posed a great threat to human life, and the necessity of its monitoring and treatment is decided by symptomatology and/or the aneurysm size. Accumulating evidence suggests that circular RNAs (circRNAs) contribute a part to the pathogenesis of AAAs. circRNAs are novel single-stranded RNAs with a closed loop structure and high stability, having become the candidate biomarkers for numerous kinds of human disorders. Besides, circRNAs act as molecular "sponge" in organisms, capable of regulating the transcription level. Here, we characterize that the molecular mechanisms underlying the role of circRNAs in AAA development were further elucidated. In the present work, studies on the biosynthesis, bibliometrics, and mechanisms of action of circRNAs were aims comprehensively reviewed, the role of circRNAs in the AAA pathogenic mechanism was illustrated, and their potential in diagnosing AAAs was examined. Moreover, the current evidence about the effects of circRNAs on AAA development through modulating endothelial cells (ECs), macrophages, and vascular smooth muscle cells (VSMCs) was summarized. Through thorough investigation, the molecular mechanisms underlying the role of circRNAs in AAA development were further elucidated. The results demonstrated that circRNAs had the application potential in the diagnosis and prevention of AAAs in clinical practice. The study of circRNA regulatory pathways would be of great assistance to the etiologic research of AAAs.

Imaging Biological Pathways in Abdominal Aortic Aneurysms Using Positron Emission Tomography

[Figure: see text].

Time-Dependent Pathological Changes in Hypoperfusion-Induced Abdominal Aortic Aneurysm

Simple Summary

Abdominal aortic aneurysm (AAA) is a vascular disease that involves gradual dilation of the abdominal aorta and has a high mortality due to rupture. Hypoperfusion due to the obstruction of vasa vasorum, which is a blood supply system in the aortic wall, may be an important factor involved in AAA pathophysiology. A time-dependent analysis is important to understand the pathological cascade following hypoperfusion in the aortic wall. In our study, time-dependent analysis using a hypoperfusion-induced animal model showed that the dynamics of many AAA-related factors might be associated with the increased hypoxia-inducible factor-1α level. Hypoperfusion due to stenosis of the vasa vasorum might be a new drug target for AAA therapeutics.

Abstract

Hypoperfusion due to vasa vasorum stenosis can cause wall hypoxia and abdominal aortic aneurysm (AAA) development. Even though hypoperfusion is an important contributor toward pathological changes in AAA, the correlation between hypoperfusion and AAA is not fully understood. In this study, a time-dependent semi-quantitative pathological analysis of hypoperfusion-induced aortic wall changes was performed to understand the mechanisms underlying the gradual degradation of the aortic wall leading to AAA formation. AAA-related factors evaluated in this study were grouped according to the timing of dynamic change, and five groups were formed as follows: first group: angiotensin II type 1 receptor, endothelin-1 (ET-1), and malondialdehyde (MDA); second group: matrix metalloproteinase (MMP)-2, -9, -12, M1 macrophages (Mac387+ cells), and monocyte chemotactic protein-1; third group: synthetic smooth muscle cells (SMCs); fourth group: neutrophil elastase, contractile SMCs, and angiotensinogen; and the fifth group: M2 macrophages (CD163+ cells). Hypoxia-inducible factor-1α, ET-1, MDA, and MMP-9 were colocalized with alpha-smooth muscle actin cells in 3 h, suggesting that hypoperfusion-induced hypoxia directly affects the activities of contractile SMCs in the initial stage of AAA. Time-dependent pathological analysis clarified the cascade of AAA-related factors. These findings provide clues for understanding complicated multistage pathologies in AAA.

Inhibition of miR-188-5p Suppresses Progression of Experimental Abdominal Aortic Aneurysms

ABSTRACT

Abdominal aortic aneurysm (AAA) is an aging-related degenerative disease. miR-188-5p was reported to induce cell senescence and play a key role in aging-related disease. Therefore, in this study, we investigated miR-188-5p expression during progression in experimental AAAs. Furthermore, we investigated whether inhibition of miR-188-5p could suppress AAA progression. Experimental AAAs were created in 9-12-week-old male C57BL/6J mice by transient intra-aortic infusion of porcine pancreatic elastase. Expression of miR-188-5p levels were assessed in aneurysmal and control aortae during the progression of aneurysm. For inhibition experiment, miR-188 inhibiting group mice were injected with AAV2-miR188-5p sponge through tail vein and control group mice were injected with AAV2-CMV-GFP. Influences on experimental AAA progression were assessed by measurements of aortic diameter and histopathologic analysis at sacrifice. Meanwhile, immunohistochemistry and fluorescence in situ hybridization were used to determine the inflammatory cells infiltration and colocalization of miR-188-5p in aortic sections. Expression of miR-188-5p is upregulated during progression of AAA. Importantly, miR-188-5p inhibition treatment prevented enlargement of experimental aneurysms. Meanwhile, miR-188-5p inhibition regimens attenuated medial elastin degradation, smooth muscle cell depletion, and mural angiogenesis and the accumulation of macrophages, T cells, and angiogenesis. Furthermore, colocalization of miR188-5p with CD68 and CD3 was observed, which suggest miR-188-5p was expressed mainly in infiltrated macrophages and T cells. Expression of miR-188-5p is increased in experimental AAAs. Treatment with miR-188-5p inhibition limits experimental AAA progression, with histologic evidence of reduced neovessels and attenuated mural leukocyte infiltration. These findings underscore the potential significance of miR-188-5p in aneurysm pathogenesis and as a target for suppression of AAA disease.

The time has come to extend the expiration limit of cryopreserved allograft heart valves

Despite the wide choice of commercial heart valve prostheses, cryopreserved semilunar allograft heart valves (C-AHV) are required, and successfully transplanted in selected groups of patients. The expiration limit (EL) criteria have not been defined yet. Most Tissue Establishments (TE) use the EL of 5 years. From physiological, functional, and surgical point of view, the morphology and mechanical properties of aortic and pulmonary roots represent basic features limiting the EL of C-AHV. The aim of this work was to review methods of AHV tissue structural analysis and mechanical testing from the perspective of suitability for EL validation studies. Microscopic structure analysis of great arterial wall and semilunar leaflets tissue should clearly demonstrate cells as well as the extracellular matrix components by highly reproducible and specific histological staining procedures. Quantitative morphometry using stereological grids has proved to be effective, as the exact statistics was feasible. From mechanical testing methods, tensile test was the most suitable. Young's moduli of elasticity, ultimate stress and strain were shown to represent most important AHV tissue mechanical characteristics, suitable for exact statistical analysis. C-AHV are prepared by many different protocols, so as each TE has to work out own EL for C-AHV.