AAA Development Research Articles

Longitudinal study on 3D ultrasound-based rupture risk assessment of Abdominal Aortic Aneurysms.

Image-based, patient-specific rupture risk analysis of AAAs is promising but it is limited by invasive and costly imaging modalities. Ultrasound (US) offers a safe, more affordable alternative, allowing multiple assessments during follow-up and enabling longitudinal studies on AAA rupture risk. This study used time-resolved three-dimensional US to assess AAA rupture risk parameters over time, based on vessel and intraluminal thrombus (ILT) geometry. The locations and magnitude of peak wall rupture index (PWRI), peak wall stress (PWS), and maximum ILT thickness for varying AAA growth rates, and the correlation between PWRI, PWS, and geometric parameters were investigated.This study demonstrated that US-based biomechanical analysis is suitable for assessing rupture potential, providing insights into the evolution through various phases in AAA development. For the fast-growing AAAs, the location of PWRI moved closer to the locations of maximum ILT thickness, whereas the location of PWS moved further away. The newly introduced parameter, i.e., percentage of ILT expected for an aneurysm with a healthy lumen, showed a stronger correlation with PWS and PWRI and was less dependent on AAA size, indicating the potential for further research on ILT's impact on AAA rupture risk. This study represents a step towards clinical introduction of US-based AAA rupture risk analysis. Further research and randomized trials are required to directly correlate PWRI with rupture risk. Further improvement of ILT visibility and personalization of the US-based models will be required to achieve clinical acceptance of model-based rupture risk predictions.

Integrative analysis of single-Cell RNA sequencing and experimental validation in the study of abdominal aortic aneurysm progression

BackgroundAbdominal aortic aneurysm (AAA) is a complex vascular disorder characterized by the progressive dilation of the abdominal aorta, with a high risk of rupture and mortality.Understanding the cellular interactions and molecular mechanisms underlying AAA development is critical for identifying potential therapeutic targets. MethodsThis study utilized datasets GSE197748, GSE164678 and GSE183464 from the GEO database, encompassing bulk and single-cell RNA sequencing data from AAA and control samples. We performed principal component analysis, differential expression analysis, and functional enrichment analysis to identify key pathways involved in AAA. Cell-cell interactions were investigated using CellPhoneDB, focusing on fibroblasts, vascular smooth muscle cells (VSMCs), and macrophages. We further validated our findings using a mouse model of AAA induced by porcine pancreatic enzyme infusion, followed by gene expression analysis and co-immunoprecipitation experiments. ResultsOur analysis revealed significant alterations in gene expression profiles between AAA and control samples, with a pronounced immune response and cell adhesion pathways being implicated. Single-cell RNA sequencing data highlighted an increased proportion of pro-inflammatory macrophages, along with changes in the composition of fibroblasts and VSMCs in AAA. CellPhoneDB analysis identified critical ligand-receptor interactions, notably collagen type I alpha 1 chain (COL1A1)/COL1A2-CD18 and thrombospondin 1 (THBS1)-CD3, suggesting complex communication networks between fibroblasts and VSMCs. In vivo experiments confirmed the upregulation of these genes in AAA mice and demonstrated the functional interaction between COL1A1/COL1A2 and CD18. ConclusionThe interaction between fibroblasts and VSMCs, mediated by specific ligand-receptor pairs such as COL1A1/COL1A2-CD18 and THBS1-CD3, plays a pivotal role in AAA pathogenesis.

Targeting the smooth muscle cell KEAP1-Nrf2-STING axis with pterostilbene attenuates abdominal aortic aneurysm

BackgroundAbdominal aortic aneurysm (AAA) is a life-threatening aortic disease, and to date, there are currently no effective pharmacological treatments to address this condition. Activation of cytosolic DNA sensing adaptor stimulator of interferon genes (STING) signaling is a crucial mechanism in AAA formation. PurposeThis study investigated pterostilbene (Pt), a naturally occurring polyphenol and resveratrol analogue, as a STING inhibitor for preventing AAA. MethodsWe evaluated the effect of Pt on AAA formation in angiotensin II (AngII)-infused apolipoprotein E-deficient (ApoE−/−) mice. We used histological analysis, MMP activity measurement, western blot, and immunohistochemistry to detect AAA formation and development. We applied RNA sequencing, molecular docking, cellular thermal shift assay (CETSA) and functional studies to dissect the molecular mechanism of Pt-regulating KEAP1-Nrf2-STING signaling. We conditionally knocked down Nrf2 in vascular smooth muscle cells (VSMCs) in vivo to investigate its role in Pt-mediated protective effects on AAA. ResultsPt effectively blocked the formation of AAA in AngII-infused ApoE−/− mice. Whole transcriptome sequencing analysis revealed that nuclear factor erythroid 2-related factor 2 (Nrf2) and STING pathway in VSMCs were linked to the anti-AAA effects of pterostilbene. Mechanistically, Pt upregulated Nrf2 target genes (e.g., HO-1 and NQO1) through activation of the KEAP1/Nrf2 signaling, which restricted the immunostimulatory axis of mtDNA-STING-TBK1-NF-κB, thereby alleviating VSMC inflammation and preserving the VSMC contractile phenotype. Subsequently, molecular docking and CETSA revealed a binding mode between Pt and KEAP1/Nrf2. Intriguingly, the inhibitory effect of Pt on STING signaling and the protective role of Pt in AAA were largely abrogated by VSMC-specific Nrf2 knockdown in mice. ConclusionCollectively, naturally derived Pt shows promising efficacy for the treatment of AAA by targeting the KEAP1-Nrf2-STING axis in VSMCs.

ATG4B as a novel biomarker for abdominal aortic aneurysm: integrated evaluation through experimental and bioinformatics analyses.

Autophagy related gene 4B (ATG4B) plays a central role in autophagy machinery, but its clinical relevance to AAA remains unknown. In this study, 205 AAA patients and 205age- and sex-matched controls were included to detect the serum ATG4B levels. Meanwhile, abdominal aortic specimens from 24 AAA patients and 6 human organ donors were collected to evaluate the mRNA and in situ protein expression of ATG4B. We observed significantly higher ATG4B mRNA and protein expression levels in AAA group compared to those in control group, with a positive correlation between mRNA levels and serum/in situ protein levels (serum, r = 0.518, P = 0.010; in situ, r = 0.453, P = 0.026). Serum ATG4B exhibited the diagnostic potential for AAA (AUC = 0.702, sensitivity = 75.6%) and intraluminal thrombus recognition (AUC = 0.602, sensitivity = 67.9%). Logistic regression revealed a significant association between elevated serum ATG4B and an increased risk of AAA and intraluminal thrombus formation. Deceased patients displayed higher baseline serum ATG4B levels, which could predict postoperative mortality (HR = 1.028, 95%CI = 1.007-1.049, P = 0.009, AUC = 0.612, sensitivity = 84.6%). The bioinformatics analysis suggested that ATG4B may modulate cellular autophagy and influence pathways associated with inflammation, lipid metabolism, or apoptosis, thereby contributing to the occurrence and development of AAA. The drug-gene interaction network identified 13 potential therapeutic drugs targeting ATG4B. In conclusion, ATG4B may serve as a promising biomarker for the diagnosis and prognostic assessment of AAA patients and play a key role in the pathogenesis of AAA.

Identification of abdominal aortic aneurysm subtypes based on mechanosensitive genes.

Rupture of abdominal aortic aneurysm (rAAA) is a fatal event in the elderly. Elevated blood pressure and weakening of vessel wall strength are major risk factors for this devastating event. This present study examined whether the expression profile of mechanosensitive genes correlates with the phenotype and outcome, thus, serving as a biomarker for AAA development. In this study, we identified mechanosensitive genes involved in AAA development using general bioinformatics methods and machine learning with six human datasets publicly available from the GEO database. Differentially expressed mechanosensitive genes (DEMGs) in AAAs were identified by differential expression analysis. Molecular biological functions of genes were explored using functional clustering, Protein-protein interaction (PPI), and weighted gene co-expression network analysis (WGCNA). According to the datasets (GSE98278, GSE205071 and GSE165470), the changes of diameter and aortic wall strength of AAA induced by DEMGs were verified by consensus clustering analysis, machine learning models, and statistical analysis. In addition, a model for identifying AAA subtypes was built using machine learning methods. 38 DEMGs clustered in pathways regulating 'Smooth muscle cell biology' and 'Cell or Tissue connectivity'. By analyzing the GSE205071 and GSE165470 datasets, DEMGs were found to respond to differences in aneurysm diameter and vessel wall strength. Thus, in the merged datasets, we formally created subgroups of AAAs and found differences in immune characteristics between the subgroups. Finally, a model that accurately predicts the AAA subtype that is more likely to rupture was successfully developed. We identified 38 DEMGs that may be involved in AAA. This gene cluster is involved in regulating the maximum vessel diameter, degree of immunoinflammatory infiltration, and strength of the local vessel wall in AAA. The prognostic model we developed can accurately identify the AAA subtypes that tend to rupture.

Innate immunity of vascular smooth muscle cells contributes to two-wave inflammation in atherosclerosis, twin-peak inflammation in aortic aneurysms and trans-differentiation potential into 25 cell types.

Vascular smooth muscle cells (VSMCs) are the predominant cell type in the medial layer of the aorta, which plays a critical role in aortic diseases. Innate immunity is the main driving force for cardiovascular diseases. To determine the roles of innate immunity in VSMC and aortic pathologies, we performed transcriptome analyses on aortas from ApoE-/- angiotensin II (Ang II)-induced aortic aneurysm (AAA) time course, and ApoE-/- atherosclerosis time course, as well as VSMCs stimulated with danger-associated molecular patterns (DAMPs). We made significant findings: 1) 95% and 45% of the upregulated innate immune pathways (UIIPs, based on data of 1226 innate immune genes) in ApoE-/- Ang II-induced AAA at 7 days were different from that of 14 and 28 days, respectively; and AAA showed twin peaks of UIIPs with a major peak at 7 days and a minor peak at 28 days; 2) all the UIIPs in ApoE-/- atherosclerosis at 6 weeks were different from that of 32 and 78 weeks (two waves); 3) analyses of additional 12 lists of innate immune-related genes with 1325 cytokine and chemokine genes, 2022 plasma membrane protein genes, 373 clusters of differentiation (CD) marker genes, 280 nuclear membrane protein genes, 1425 nucleoli protein genes, 6750 nucleoplasm protein genes, 1496 transcription factors (TFs) including 15 pioneer TFs, 164 histone modification enzymes, 102 oxidative cell death genes, 68 necrotic cell death genes, and 47 efferocytosis genes confirmed two-wave inflammation in atherosclerosis and twin-peak inflammation in AAA; 4) DAMPs-stimulated VSMCs were innate immune cells as judged by the upregulation of innate immune genes and genes from 12 additional lists; 5) DAMPs-stimulated VSMCs increased trans-differentiation potential by upregulating not only some of 82 markers of 7 VSMC-plastic cell types, including fibroblast, osteogenic, myofibroblast, macrophage, adipocyte, foam cell, and mesenchymal cell, but also 18 new cell types (out of 79 human cell types with 8065 cell markers); 6) analysis of gene deficient transcriptomes indicated that the antioxidant transcription factor NRF2 suppresses, however, the other five inflammatory transcription factors and master regulators, including AHR, NF-KB, NOX (ROS enzyme), PERK, and SET7 promote the upregulation of twelve lists of innate immune genes in atherosclerosis, AAA, and DAMP-stimulated VSMCs; and 7) both SET7 and trained tolerance-promoting metabolite itaconate contributed to twin-peak upregulation of cytokines in AAA. Our findings have provided novel insights on the roles of innate immune responses and nuclear stresses in the development of AAA, atherosclerosis, and VSMC immunology and provided novel therapeutic targets for treating those significant cardiovascular and cerebrovascular diseases.

Colchicine ameliorates short-term abdominal aortic aneurysms by inhibiting the expression of NLRP3 inflammasome components in mice

BackgroundAbdominal aortic aneurysms (AAA) are often associated with chronic inflammation and pose a significant risk to affected individuals. Colchicine, known for its anti-inflammatory properties, has shown promise in managing cardiovascular diseases. However, its specific role in the development of AAA remains poorly understood. Methods and resultsIn this study, we employed a short-term AAA model induced by angiotensin II (Ang II, 1000 ng/kg/min) and calcium chloride (CaCl2, 0.5 mol/l) in male ApoE-/- and C57BL/6 mice (8–12 weeks old) to investigate the effects of colchicine on AAA progression. Colchicine (0.4 mg/kg) was administered orally once daily, starting on the same day as AAA induction. After a 4-week duration, we observed a significant reduction in AAA diameter, degradation of elastic fibers, and expression of components related to the Nucleotide-binding oligomerization domain-like receptor family protein 3 (NLRP3) inflammasome in the vessel wall of colchicine-treated mice compared to the saline group. Mechanistically, colchicine (5 μm/l, for 24h) inhibited the expression of NLRP3 inflammasome components through the P38-ERK/MicroRNA145-toll-like receptor 4 (TLR4) pathway in RAW264.7 cells. ConclusionsOur study demonstrates the effectiveness of colchicine in suppressing NLRP3 inflammasome components, thereby delaying AAA progression in the Ang II and CaCl2-induced short-term model. These findings suggest the potential of colchicine as a pharmacological treatment option for AAA.

Loss of TIMP3, but not TIMP4, exacerbates thoracic and abdominal aortic aneurysm

AimsAorta exhibits regional heterogeneity (structural and functional), while different etiologies for thoracic and abdominal aortic aneurysm (TAA, AAA) are recognized. Tissue inhibitor of metalloproteinases (TIMPs) regulate vascular remodeling through different mechanisms. Region-dependent functions have been reported for TIMP3 and TIMP4 in vascular pathologies. We investigated the region-specific function of these TIMPs in development of TAA versus AAA. Methods & resultsTAA or AAA was induced in male and female mice lacking TIMP3 (Timp3−/−), TIMP4 (Timp4−/−) or in wildtype (WT) mice by peri-adventitial elastase application. Loss of TIMP3 exacerbated TAA and AAA severity in males and females, with a greater increase in proteinase activity, smooth muscle cell phenotypic switching post-AAA and -TAA, while increased inflammation was detected in the media post-AAA, but in the adventitia post-TAA. Timp3−/− mice showed impaired intimal barrier integrity post-AAA, but a greater adventitial vasa-vasorum branching post-TAA, which could explain the site of inflammation in AAA versus TAA. Severity of TAA and AAA in Timp4−/− mice was similar to WT mice. In vitro, Timp3 knockdown more severely compromised the permeability of human aortic EC monolayer compared to Timp4 knockdown or the control group. In aneurysmal aorta specimens from patients, TIMP3 expression decreased in the media in AAA, and in adventitial in TAA specimens, consistent with the impact of its loss in AAA versus TAA in mice. ConclusionTIMP3 loss exacerbates inflammation, adverse remodeling and aortic dilation, but triggers different patterns of remodeling in AAA versus TAA, and through different mechanisms.

The presence of activating IgG Fc receptors in macrophages aggravates the development of experimental abdominal aortic aneurysm

IntroductionAbdominal aortic aneurysm (AAA) is a multifactorial, degenerative disease characterized by progressive aortic dilation and chronic activation of inflammation, proteolytic activity, and oxidative stress in the aortic wall. The immune response triggered by antibodies against antigens present in the vascular wall participates in the formation and progression of AAA through mechanisms not completely understood. This work analyses the function of specific IgG receptors (FcγR), especially those expressed by monocytes/macrophages, in the development of experimental AAA. MethodsIn the elastase-induced AAA model, the abdominal aortas from wildtype and FcγR deficient mice with/without macrophage adoptive transfer were analysed by histology and quantitative PCR. In vitro, RAW 264.7 macrophages were transfected with RNA interference of FcγRIV/CD16.2 or treated with Syk kinase inhibitor before stimulation with IgG immune complexes. ResultsMacrophage adoptive transfer in FcγR deficient mice increased the susceptibility to AAA development. Mice receiving macrophages with functional FcγR exhibited higher aortic diameter increase, higher content of macrophages and B lymphocytes, and upregulated expression of chemokine CCL2, cytokines (TNFα and IL-17), metalloproteinase MMP2, prooxidant enzyme NADPH oxidase-2, and the isoforms FcγRIII/CD16 and FcγRIV/CD16.2. In vitro, both FcγRIV/CD16.2 gene silencing and Syk inhibition reduced cytokines and reactive oxygen species production induced by IC in macrophages. ConclusionsActivation of macrophage FcγR contributes to AAA development by inducing mediators of inflammation, proteolysis, and oxidative stress. Modulation of FcγR or effector molecules may represent a potential target for AAA treatment.

Loss of tissue inhibitor of proteinase 3 (TIMP3), but not TIMP4, worsens abdominal and thoracic aortic aneurysm

Background: Aorta exhibits regional heterogeneity (structural and mechanical), while different etiologies for thoracic and abdominal aortic aneurysm (TAA, AAA) are recognized. Tissue inhibitor of metalloproteinases (TIMPs) regulate vascular remodeling through different mechanisms. TIMP3 and TIMP4 have shown region-dependent functions in aortic pathologies. We investigated the region-specific function of these TIMPs in development of TAA versus AAA. Methods and Results: TAA or AAA was induced in male or female mice lacking TIMP3 ( Timp3 -/- ), TIMP4 ( Timp4 -/- ) or wildtype (WT) mice by peri-adventitial elastase application. Loss of TIMP3 exacerbated TAA and AAA severity in males and females. Timp3 -/- mice exhibited a greater increase in proteinase activity, smooth muscle cell phenotypic switching post-AAA and -TAA whereas inflammation increased in the media post-AAA, but in the adventitia post-TAA. Timp3 -/- mice showed impaired intimal barrier integrity ( in vivo) following AAA, but a greater adventitial vasa-vasorum branching post-TAA, which could explain the site of inflammation in TAA versus AAA. Timp4 -/- mice responded similarly to TAA and AAA induction as the WT. In vitro, Timp3 knockdown in human aortic EC more severely compromised the EC monolayer permeability compared to Timp4 knockdown and control groups following elastase treatment. In human aorta specimens, TIMP3 showed a region-specific expression pattern in TAA versus AAA consistent with the impact of its loss in the impaired intimal barrier in AAA, and the adventitial region in TAA. Conclusions: TIMP3 plays a protective role in both AAA and TAA, whereas loss of TIMP4 has minimal impact on the severity of aneurysm formation. TIMP3 loss in the aneurysmal aorta could be responsible for the inflammation, adverse remodeling and aortic dilation in AAA and TAA, through different mechanisms. Support: CIHR, Heart and Stroke. CIHR, Heart and Stroke. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

La presencia de receptores Fc de IgG activadores en macrófagos agrava el desarrollo de aneurisma aórtico abdominal experimental

IntroductionAbdominal aortic aneurysm (AAA) is a multifactorial, degenerative disease characterized by progressive aortic dilation and chronic activation of inflammation, proteolytic activity, and oxidative stress in the aortic wall. The immune response triggered by antibodies against antigens present in the vascular wall participates in the formation and progression of AAA through mechanisms not completely understood. This work analyses the function of specific IgG receptors (FcγR), especially those expressed by monocytes/macrophages, in the development of experimental AAA. MethodsIn the elastase-induced AAA model, the abdominal aortas from wildtype and FcγR deficient mice with/without macrophage adoptive transfer were analysed by histology and quantitative PCR. In vitro, mouse macrophages were transfected with RNA interference of FcγRIV/CD16.2 or treated with Syk kinase inhibitor before stimulation with IgG immune complexes. ResultsMacrophage adoptive transfer in FcγR deficient mice increased the susceptibility to AAA development. Mice receiving macrophages with functional FcγR exhibited higher aortic diameter increase, higher content of macrophages and B lymphocytes, and upregulated expression of chemokine CCL2, cytokines (TNF-α and IL-17), metalloproteinase MMP2, prooxidant enzyme NADPH oxidase-2, and the isoforms FcγRIII/CD16 and FcγRIV/CD16.2. In vitro, both FcγRIV/CD16.2 gene silencing and Syk inhibition reduced cytokines and reactive oxygen species production induced by immune complexes in macrophages. ConclusionsActivation of macrophage FcγR contributes to AAA development by inducing mediators of inflammation, proteolysis, and oxidative stress. Modulation of FcγR or effector molecules may represent a potential target for AAA treatment.

No differences in FBN1 genotype between men with and without abdominal aortic aneurysm

BackgroundAbdominal aortic aneurysm (AAA) is an aortic enlargement in which the transverse diameter reaches at least 30 mm. Certain risk factors, such as age, male gender, and smoking, are well known; however, less is known about the genetic factors involved. Fibrillin-1 (FBN1) is a protein that coordinates the deposition of elastin fibres in the extracellular matrix and is therefore likely to affect the elastic properties in the aortic wall. Previously studies have found associations between the FBN1-2/3 genotype and arterial stiffness, but how different FBN1 genotypes, AAA, and arterial stiffness are related has been less frequently investigated.AimThis study aimed to investigate whether there is a difference in FBN1 genotype between men with and without AAA. A further aim was to study whether the FBN1 genotype affects arterial wall stiffness differently in men with and without AAA.MethodsPulse wave velocity and FBN1 genotyping were performed in 229 men (159 with AAA, 70 without AAA). Participants were recruited from ultrasound AAA surveillance programs or ongoing ultrasound screening programs from 2011 to 2016.ResultsThe distribution of the FBN1 genotype in the AAA and control groups were as follows: FBN1-2/2: 62% vs. 64%; FBN1-2/3: 8% vs. 14%; and FBN1-2/4: 30% vs. 21%, respectively. Men with AAA and FBN1-2/2 had increased central pulse wave velocity (p < 0.005) compared to the control group (those without AAA) with the FBN1-2/2 genotype.ConclusionNo differences were found with respect to FBN1 genotypes between men with and without AAA. The development of AAA in men does not appear to be linked to a specific FBN1 genotype. Nevertheless, men with FBN1-2/2 and AAA have increased central arterial stiffness compared to men with the same FBN1 genotype but without AAA.

Alpha-lipoic acid protects against aortic aneurysm and dissection by improving vascular smooth muscle cell function

Alpha-Lipoic acid (ALA) plays a protective role in a variety of vascular diseases, however, its effect on aortic aneurysm and dissection (AAD) has not been reported. In this study, we found that Alpha-Lipoic Acid treatment significantly improved the AAD and AAA development, which was demonstrated by ameliorated aneurysmal dilation, decreased aortic dissection and aneurysm incidence, improved aortic morphology and inhibited elastin degradation. ALA blunted extra-cellular matrix degradation, vascular smooth muscle cell (VSMC) loss and phenotype transformation. Moreover, the protective effect of ALA on VSMCs may be related to the amelioration of mitochondrial dysfunction. In conclusion, our study revealed that ALA exerts inhibitory effects against progression of AAD, thus suggesting that ALA may be a novel therapeutic molecule for AAD.

Galactose-modified nanoparticles for delivery of microRNA to mitigate the progress of abdominal aortic aneurysms via regulating macrophage polarization

BackgroundAbdominal aortic aneurysms (AAA) are chronic inflammation in nature and are closely related to macrophages. The purpose was to explore regulating macrophage polarization with target-macrophage nanoparticles impacting the development of AAA. MethodsGalactose-modified nanoparticles were prepared by self-assembly technology for delivering microRNA (miR)-223. In AngiotensinII-induced experimental AAA model, miR-223-loaded nanoparticles (MirNPs) or PBS was injected at day 7 before and after operation, respectively. Cultured cells and aortic specimen were collected to be analyzed with histology and biochemical examination. ResultsIn vitro, miR-223 promoted bone marrow-derived macrophages (BMDMs) to polarize to M2. In experimental AAA model, MirNPs significantly decreased the AAA incidence and the ratio of M1 macrophages and production of related proinflammatory cytokines. Furthermore, MirNPs also reduced the expression of the NLRP3 inflammasome. ConclusionOur findings suggested that miR-223-loaded nanoparticles targeting macrophage polarization may mitigate AAA progression via downregulating of NLRP3.

Abdominal Aortic Aneurysm and Plasminogen Activator Inhibitor 1: Correlation in the Context of Type 2 Diabetes

BackgroundAbdominal Aortic Aneurysm (AAA) is a progressive, inflammatory disease of the infrarenal aorta, characterized by irreversible aortic dilation. Despite decades of research, AAA pathogenesis remains poorly understood, and no pharmaceutical therapies to slow aortic growth have been identified. Interestingly, the only condition known to be associated with decreased rates of aortic growth and rupture in AAA patients is a diagnosis of Type 2 Diabetes Mellitus (T2DM). Our laboratory has demonstrated that streptozotocin (STZ)‐induced hyperglycemia inhibits aortic dilation in a mouse model of AAA. Plasminogen Activator Inhibitor 1 (PAI‐1), a key player in the fibrinolytic pathway, has been shown to be elevated in both Type 1 and T2DM patients and hyperglycemic mice. Additionally, studies have demonstrated that local application of PAI‐1 is effective in inhibiting AAA development in a murine model.ObjectiveThe purpose of the present study was to determine the role of PAI‐1 expression in hyperglycemic protection against AAA growth.HypothesisWe predicted that elevated PAI‐1 is responsible for decreased fibrinolysis leading to inhibited aortic growth in patients with both diabetes and AAA. Based on this hypothesis, we proposed that hyperglycemic mice deficient in PAI‐1 (PAI‐1 KO) would not demonstrate the protection from AAA growth observed in hyperglycemic C57BL/6J (C57) control mice.MethodsFasting blood glucose (BG; mg/dL) was measured in 6‐week‐old C57 and PAI‐1 KO mice at baseline on experimental day (D)0, and STZ (40 mg/kg) was intraperitoneally administered daily from D0 to D4. Sodium citrate buffer (SC; vehicle) was administered to control mice. On D14, final BG was measured to confirm hyperglycemia (≥250 mg/dL). On D21, mice underwent laparotomy: a midline abdominal incision was made and the infrarenal aorta was isolated. After measuring aortic diameter midway between the renal arteries and iliac bifurcation, pancreatic porcine elastase (PPE; 60 U/mL) was applied to the adventitial aorta for 5 minutes. The aorta and surrounding structures were then washed twice with 0.9% sterile saline. Control mice received heat‐inactivated PPE. On D49, the incision was reopened, and the aorta was isolated and measured at the widest point of dilation.ResultsSTZ‐treated C57 mice experienced significantly reduced AAA diameter compared to SC‐treated C57 controls (p&lt; 0.0001) 4 weeks post‐induction. However, differences in AAA diameter were not observed under the same treatment conditions in PAI‐1 KO mice (p= 0.290). Percent increase in aortic diameter in both STZ‐ and SC‐treated PAI‐1 KO mice induced with AAA was significantly reduced compared to that of SC‐treated C57 mice (p&lt; 0.01 and p &lt; 0.0001, respectively).ConclusionsOur study demonstrated that PAI‐1 is elevated in mice with STZ‐induced diabetes. While hyperglycemic mice show significantly reduced AAA growth compared to normoglycemic AAA controls, no difference in aortic growth is observed between hyperglycemic and normoglycemic PAI‐1 KO mice. Regardless of treatment status, PAI‐1 deficient mice experience significantly reduced AAA growth compared to C57 control mice. We conclude that while the fibrinolytic pathway and PAI‐1 are influential in AAA development, hyperglycemia‐induced elevated PAI‐1 expression does not play a crucial role in hyperglycemic inhibition of AAA growth. Conversely, PAI‐1 deficiency appears to inhibit AAA growth regardless of glycemic status.

Abstract P109: Angiotensin 1-7 Attenuates Angiotensin II-induced Aortic Aneurysm In A Preclinical Murine Model

Background: Aortic aneurysm (AA) is a vascular disease that involves extracellular matrix degeneration of the aorta wall leading to dilatation and eventually aorta wall rupture. Aortic aneurysms contribute significantly to global morbidity and mortality due to vascular diseases. Elusive pathophysiology of initiation and progression of aortic aneurysm led to the absence of clinically relevant therapeutic interventions against aortic aneurysm. Though the role of AngII in the development and progression of AA is widely studied, the effect of Ang 1-7 on hallmarks of AA i.e. SMCs apoptosis, aorta matrix remodeling, and inflammation are poorly understood. Methods and Results: In the present study, we have investigated Ang 1-7-mediated protective effect on the AngII-infused murine model. AngII-infused ApoEKO murine model showed aortic dilatation in the thoracic and abdominal region with matrix remodeling. Infusion of Ang 1-7 rescued the phenotype evident by echocardiography. While histology staining showed excessive matrix remodeling i.e. collagen deposition in thoracic aorta and immunofluorescence showed VSMCs cell death in the abdominal aorta, suggesting different mechanisms underlying the development of TAA and AAA. The inflammatory markers, MMP2, MMP9, and TNF-α were significantly reduced in the thoracic aorta post-infusion of Ang 1-7. The Ang 1-7 treatment led to a reduced phenotypic switch in abdominal VSMCs evident by increased expression of ACTA2, MyH11, Calponin and reduced expressions of MMP2, MMP9, Collagen I, and collagen III. The apoptosis assay using flow cytometry showed attenuation of cell death of abdominal VSMCs after infusion of Ang 1-7 in a murine model of AA. The analysis of apoptosis-associated proteins, Caspase 3 and 8, showed reduced expression in the abdominal aorta. Conclusion: The study showed mitigation of AngII-mediated AA by Ang 1-7 infusion. Ang 1-7 treatment attenuated AngII-induced TAA by suppressing aortic matrix remodeling and AAA by inhibiting VSMCs apoptosis and vascular inflammation. Ang 1-7 can be a potential therapeutic alternative for the treatment of AA.

Nuclear Receptor Nur77 Protects Against Abdominal Aortic Aneurysm by Ameliorating Inflammation Via Suppressing LOX‐1

BackgroundAbdominal aortic aneurysm (AAA) is a life‐threatening vascular disorder characterized by chronic inflammation of the aortic wall, which lacks effective pharmacotherapeutic remedies and has an extremely high mortality. Nuclear receptor NR4A1 (Nur77) functions in various chronic inflammatory diseases. However, the influence of Nur77 on AAA has remained unclear. Herein, we sought to determine the effects of Nur77 on the development of AAA.Methods and ResultsWe observed that Nur77 expression decreased significantly in human and mice AAA lesions. Deletion of Nur77 accelerated the development of AAA in mice, as evidenced by increased AAA incidence, abdominal aortic diameters, elastin fragmentation, and collagen content. Consistent with genetic manipulation, pharmacological activation of Nur77 by celastrol showed beneficial effects against AAA. Microscopic and molecular analyses indicated that the detrimental effects of Nur77 deficiency were associated with aggravated macrophage infiltration in AAA lesions and increased pro‐inflammatory cytokines secretion and matrix metalloproteinase (MMP‐9) expression. Bioinformatics analyses further revealed that LOX‐1 was upregulated by Nur77 deficiency and consequently increased the expression of cytokines and MMP‐9. Moreover, rescue experiments verified that LOX‐1 notably aggravated inflammatory response, an effect that was blunted by Nur77.ConclusionsThis study firstly demonstrated a crucial role of Nur77 in the formation of AAA by targeting LOX‐1, which implicated Nur77 might be a potential therapeutic target for AAA.

Fcγ receptor activation mediates vascular inflammation and abdominal aortic aneurysm development.

BackgroundAbdominal aortic aneurysm (AAA), a degenerative vascular pathology characterized by permanent dilation of the aorta, is considered a chronic inflammatory disease involving innate/adaptive immunity. However, the functional role of antibody‐dependent immune response against antigens present in the damaged vessel remains unresolved. We hypothesized that engagement of immunoglobulin G (IgG) Fc receptors (FcγR) by immune complexes (IC) in the aortic wall contributes to AAA development. We therefore evaluated FcγR expression in AAA lesions and analysed whether inhibition of FcγR signaling molecules (γ‐chain and Syk kinase) influences AAA formation in mice.MethodsFcγR gene/protein expression was assessed in human and mouse AAA tissues. Experimental AAA was induced by aortic elastase perfusion in wild‐type (WT) mice and γ‐chain knockout (γKO) mice (devoid of activating FcγR) in combination with macrophage adoptive transfer or Syk inhibitor treatment. To verify the mechanisms of FcγR in vitro, vascular smooth muscle cells (VSMC) and macrophages were stimulated with IgG IC.ResultsFcγR overexpression was detected in adventitia and media layers of human and mouse AAA. Elastase‐perfused γKO mice exhibited a decrease in AAA incidence, aortic dilation, elastin degradation, and VSMC loss. This was associated with (1) reduced infiltrating leukocytes and immune deposits in AAA lesions, (2) inflammatory genes and metalloproteinases downregulation, (3) redox balance restoration, and (4) converse phenotype of anti‐inflammatory macrophage M2 and contractile VSMC. Adoptive transfer of FcγR‐expressing macrophages aggravated aneurysm in γKO mice. In vitro, FcγR deficiency attenuated inflammatory gene expression, oxidative stress, and phenotypic switch triggered by IC. Additionally, Syk inhibition prevented IC‐mediated cell responses, reduced inflammation, and mitigated AAA formation.ConclusionOur findings provide insight into the role and mechanisms mediating IgG‐FcγR‐associated inflammation and aortic wall injury in AAA, which might represent therapeutic targets against AAA disease.

The role of selected metalloproteinases and some genetic factors in the pathogenesis of abdominal aortic aneurysm

Aortic aneurysm is defined as a pathologically dilated segment of the main artery. There are three main types of aortic aneurysms: real, pseudo and dissecting. The most common aneurysms are abdominal aortic aneurysms defined as vasodilatation equal to or above 30 mm. Abdominal aortic aneurysm development is usually asymptomatic. Many various risk factors have been linked to AAA development. The pathophysiology of AAA is associated with inflammation, smooth muscle cells apoptosis and matrix degradation. The changes always result from imbalance between active matrix metalloproteinases (MMPs) and their inhibitors – TIMPs. Abdominal aorta is the most common location for the aneurysm. The risk of developing AAA increases with age. It is more common in men. Its rupture is associated with a high risk of death. The pathogenesis of AAA is complex and still not fully understood. In pathophysiological processes, aortic wall degeneration and atherosclerosis dominate. The factors involved in the pathogenesis of AAA and TAA are not quite the same. Important factors involved in the formation of AAA and increasing the risk of its rupture are MMPs. Also, polymorphisms of numerous genes have been associated with the risk of developing AAA. The two groups of factors related to AAA formation and development are presented and discussed in this work.

At Play in the Cosmos

At Play in the Cosmos is a game for University-level Astronomy courses. Designed as a collaboration between the Games + Learning + Society Center, an academic center at the University of Wisconsin-Madison, and Norton &amp; Company, Cosmos is intended to support a “game-first” model of curriculum in which students play the game before engaging in other activities. Cosmos includes about 4 hours of game play and spans the entirety of course. It includes over 25 embedded simulations that are also used for homework, lectures, and demonstrations. The design process and resulting artifact was colored by institutional constraints, specifically a lengthy pre-production that demanded extensive documentation. The subsequent development process followed a relatively linear, waterfall process and resulted in linear game. Designers attempted to mediate this linearity through a crafting system that enabled players to explore the Universe and mine celestial bodies for resources. As a game intended to compete in the market, Cosmos included a relatively high production quality led by a team experienced in AAA development processes, and the chapter focuses on the development of art styles, interfaces, and fitting voice overs in on a constrained budget and timeline.