Matrix metalloproteinases 2 and 9 work in concert to produce aortic aneurysms

Iron Overload and Abdominal Aortic Aneurysm

Abdominal aortic aneurysm (AAA) is a chronic vascular degenerative disease characterized by progressive segmental dilation of the abdominal aorta. The rupture of an AAA represents a leading cause of death in cardiovascular diseases. Despite numerous experimental and clinical studies examining potential drug targets and therapies, currently there are no pharmaceutical treatment to prevent AAA growth and rupture. Iron is an essential element in almost all living organisms and has important biological functions. Epidemiological studies have indicated that both iron deficiency and overload are associated with adverse clinical outcomes, particularly an increased risk of cardiovascular events. Recent evidence indicates that iron overload is involved in the pathogenesis of abdominal aortic aneurysms. In this review, we provide an overview of the role of iron overload in AAA progression and explore its potential pathological mechanisms. Although the exact molecular mechanisms of iron overload in the development of AAA remain to be elucidated, the inhibition of iron deposition may offer a promising strategy for preventing these aneurysms.

Circulating Matrix Metalloproteinases for Prediction of Aortic Dilatation in Children with Bicuspid Aortic Valve: A Single-Center, Observational Study

Circulating biomarkers have been proposed for early identification of aortic dilatation progression associated with bicuspid aortic valve (BAV), but matrix metalloproteinases (MMPs) are distinguished as signatures of increased extracellular matrix degradation, a landmark of aneurysm formation. The current study aims to identify the role of MMP-1, MMP-2, MMP-9, and the MMP inhibitor, TIMP-1, in identifying aortic dilation in children with BAV. We conducted a study on 73 children divided into two study groups, depending on the presence of aortic dilatation (group 1-43 BAV controls and group 2-30 children with BAV and aortic dilatation). Each patient underwent a cardiac ultrasound and, in each case, serum MMP-1, MMP-2, MMP-9, and TIMP-1 were quantified using xMAP technology. Comparison of the MMPs between the two study groups revealed significantly higher values only in the case of TIMP-1, among BAV controls. Moreover, the same TIMP-1 inversely correlated with aortic annulus absolute size and z score, as well as with ascending aorta z score. No particular correlation between the aortic phenotype and the presence of aortic dilatation was found. Future longitudinal research starting at pediatric ages could show the significance of MMPs screening in BAV individuals as predictors of aortic aneurysm formation.

Chronic intermittent hypoxia facilitates the development of angiotensin II-induced abdominal aortic aneurysm in male mice

Obstructive sleep apnea (OSA), characterized by episodes of intermittent hypoxia (IH), is highly prevalent in patients with abdominal aortic aneurysm (AAA). However, whether IH serves as an independent risk factor for AAA development remains to be investigated. Here, we determined the effects of chronic (6 mo) IH on angiotensin (Ang II)-induced AAA development in C57BL/6J male mice and investigated the underlying mechanisms of IH in cultured vascular smooth muscle cells (SMCs). IH increased the susceptibility of mice to develop AAA in response to Ang II infusion by facilitating the augmentation of the abdominal aorta's diameter as assessed by transabdominal ultrasound imaging. Importantly, IH with Ang II augmented aortic elastin degradation and the expression of matrix metalloproteinases (MMPs), mainly MMP8, MMP12, and a disintegrin and metalloproteinase-17 (ADAM17) as measured by histology and immunohistochemistry. Mechanistically, IH increased the activities of MMP2, MMP8, MMP9, MMP12, and ADAM17, while reducing the expression of the MMP regulator reversion-inducing cysteine-rich protein with Kazal motifs (RECK) in cultured SMCs. Aortic samples from human AAA were associated with decreased RECK and increased expression of ADAM17 and MMPs. These data suggest that IH facilitates AAA development when additional stressors are superimposed and that this occurs in association with an increased presence of aortic MMPs and ADAM17, potentially due to IH-induced modulation of RECK expression. These findings support a plausible synergistic link between OSA and AAA and provide a better understanding of the molecular mechanisms underlying the pathogenesis of AAA.NEW & NOTEWORTHY IH facilitates Ang II-induced abdominal aortic diameter expansion and AAA development in C57BL/6J male mice. IH upregulates the expression of specific MMPs such as MMP8, MMP12, and ADAM17. IH directly suppresses RECK expression and increases MMPs activity in SMCs. Human AAA tissues exhibit a downregulation of RECK and an upregulation of ADAM17 and MMPs.

Circulating monocyte populations as biomarker for abdominal aortic aneurysms: a single-center retrospective cohort study

Background

Abdominal aortic aneurysm (AAA) development is driven by inflammation, in particular myeloid cells, which represent attractive biomarker candidates. Yet to date, the maximum aortic diameter is the only clinically applied predictor of AAA progression and indicator for surgical repair. We postulated that aortic inflammation is reflected in a systemic change of monocyte populations, which we investigated regarding marker potential in AAA diagnosis and prognosis.

Methods

We conducted a single-center retrospective cohort study in a diagnostic setting, measuring monocyte subsets by flow cytometry in peripheral blood samples of 47 AAA patients under surveillance, matched with 25 healthy controls and 25 patients with peripheral artery disease (PAD). In a prognostic setting, we acquired longitudinal data of 60 AAA patients including aneurysm growth assessment by computed tomography at 6-month intervals.

Results

Blood levels of total monocytes, CD16+ monocytes and particularly intermediate monocytes were significantly increased in AAA patients versus healthy individuals and were also elevated compared to PAD patients. The combination of intermediate monocyte and D-dimer blood levels outperformed the individual diagnostic marker values. Additionally, the elevated concentrations of total monocytes, intermediate monocytes, and monocyte-platelet aggregates (MPA) were suited to predict rapid AAA progression over short-term periods of six months. Of note, MPA were identified as independent predictor of AAA disease progression in multivariable analysis.

Conclusion

Circulating monocyte subsets are elevated in AAA patients and support diagnosis and prediction of aneurysm progression. Monocyte subsets and D-dimer reflect different hallmarks (inflammation and hemostasis) of AAA pathology and when combined, may serve as improved biomarker.

Comparative Gene-Expression Analysis of the Ligamentum Flavum of Patients with Lumbar Spinal Canal Stenosis: Comparison between the Dural and Dorsal Sides of the Thickened Ligamentum Flavum

Thickening of the ligamentum flavum is the main factor in the development of lumbar spinal canal stenosis (LSCS). Although previous studies have reported factors related to ligamentum flavum thickening, its etiology has not been clarified. Furthermore, it is often difficult to set proper controls to investigate the pathologies of thickening due to differences in patient characteristics, such as age, sex, obesity, and comorbidities. This study aimed to elucidate the pathologies of ligamentum flavum thickening by comparing the dural and dorsal sides of the thickened ligamentum flavum in patients with LSCS. Ligamentum flavum samples were collected from 19 patients with LSCS. The samples were divided into the dural and dorsal sides. The dural side was used as a control to assess the pathologies occurring on the dorsal side. Elastic Masson staining was used to assess the elastic fibres. Gene expression levels were comprehensively assessed using quantitative reverse transcription polymerase chain reaction and DNA microarray analyses. Gene ontology analysis was used to identify biological processes associated with differentially expressed genes. The elastic fibres were significantly decreased on the dorsal side of the thickened ligamentum flavum. Genes related to fibrosis, inflammation, tissue repair, remodeling, and chondrometaplasia, such as COL1A2, COL3A1, COL5A1, TGFB1, VEGFA, TNFA, MMP2, COL10A1, and ADAMTS4, were highly expressed on the dorsal side of the thickened ligamentum flavum. The biological processes occurring on the dorsal side of the thickened ligamentum flavum were extracellular matrix organization, cell adhesion, extracellular matrix disassembly, and proteolysis.These are considered important pathologies of ligamentum flavum thickening.

Glutamine Protects against Mouse Abdominal Aortic Aneurysm through Modulating VSMC Apoptosis and M1 Macrophage Activation

Glutamine (Gln), known as the most abundant free amino acid, is widely spread in human body. In this study, we demonstrated the protective effects of glutamine against mouse abdominal aortic aneurysm (AAA) induced by both angiotensin II (AngII) and calcium phosphate (Ca3(PO4)2) in vivo, which was characterized with lower incidence of mouse AAA. Moreover, histomorphological staining visually presented more intact elastic fiber and less collagen deposition in abdominal aortas of mice treated by glutamine. Further, we found glutamine inhibited the excessive production of reactive oxide species (ROS), activity of matrix metalloproteinase (MMP), M1 macrophage activation, and apoptosis of vascular smooth muscle cells (VSMCs) in suprarenal abdominal aortas of mice, what's more, the high expressions of MMP-2 protein, MMP-9 protein, pro-apoptotic proteins, and IL-6 as well as TNF-α in protein and mRNA levels in cells treated by AngII were down-regulated by glutamine. Collectively, these results revealed that glutamine protected against mouse AAA through inhibiting apoptosis of VSMCs, M1 macrophage activation, oxidative stress, and extracellular matrix degradation.

Divergent and Compensatory Effects of BMP2 and BMP4 on the VSMC Phenotype and BMP4's Role in Thoracic Aortic Aneurysm Development

Vascular smooth muscle cells (VSMCs) play a key role in aortic aneurysm formation. Bone morphogenetic proteins (BMPs) have been implicated as important regulators of VSMC phenotype, and dysregulation of the BMP pathway has been shown to be associated with vascular diseases. The aim of this study was to investigate for the first time the effects of BMP-4 on the VSMC phenotype and to understand its role in the development of thoracic aortic aneurysms (TAAs). Using the angiotensin II (AngII) osmotic pump model in mice, aortas from mice with VSMC-specific BMP-4 deficiency showed changes similar to AngII-infused aortas, characterised by a loss of contractile markers, increased fibrosis, and activation of matrix metalloproteinase 9. When BMP-4 deficiency was combined with AngII infusion, there was a significantly higher rate of apoptosis and aortic dilatation. In vitro, VSMCs with mRNA silencing of BMP-4 displayed a dedifferentiated phenotype with activated canonical BMP signalling. In contrast, BMP-2-deficient VSMCs exhibited the opposite phenotype. The compensatory regulation between BMP-2 and BMP-4, with BMP-4 promoting the contractile phenotype, appeared to be independent of the canonical signalling pathway. Taken together, these results demonstrate the impact of VSMC-specific BMP-4 deficiency on TAA development.

Colchicine Blocks Abdominal Aortic Aneurysm Development by Maintaining Vascular Smooth Muscle Cell Homeostasis

Development of non-surgical treatment of human abdominal aortic aneurysm (AAA) has clinical significance. Colchicine emerges as an effective therapeutic regimen in cardiovascular diseases. Yet, whether colchicine slows AAA growth remain controversy. Here, we demonstrated that daily intragastric administration of low-dose colchicine blocked AAA formation, prevented vascular smooth muscle cell (SMC) phenotype switching and apoptosis, and vascular inflammation in both peri-aortic CaPO4 injury and subcutaneous angiotensin-II infusion induced experimental AAA mice models. Mechanistically, colchicine increased global mRNA stability by inhibiting the METTL14/YTHDC1-mediated m6A modification, resulting in increased sclerostin (SOST) expression and consequent inactivation of the WNT/β-catenin signaling pathway in vascular SMCs from mouse AAA lesions and in cultured human aortic SMCs. Moreover, human and mouse AAA lesions all showed increased m6A methylation, decreased SOST expression, and skewed synthetic SMC de-differentiation phenotype, compared to those without AAA. This study uncovers a novel mechanism of colchicine in slowing AAA development by using the METTL14/SOST/WNT/β-catenin axis to control vascular SMC homeostasis in mouse aortic vessels and in human aortic SMCs. Therefore, use of colchicine may benefit AAA patients in clinical practice.

Matrisome and Immune Pathways Contribute to Extreme Vascular Outcomes in Williams-Beuren Syndrome

BACKGROUND

Supravalvar aortic stenosis (SVAS) is a characteristic feature of Williams-Beuren syndrome (WBS). Its severity varies: ~20% of people with Williams-Beuren syndrome have SVAS requiring surgical intervention, whereas ~35% have no appreciable SVAS. The remaining individuals have SVAS of intermediate severity. Little is known about genetic modifiers that contribute to this variability.

METHODS AND RESULTS

We performed genome sequencing on 473 individuals with Williams-Beuren syndrome and developed strategies for modifier discovery in this rare disease population. Approaches include extreme phenotyping and nonsynonymous variant prioritization, followed by gene set enrichment and pathway-level association tests. We next used GTEx v8 and proteomic data sets to verify expression of candidate modifiers in relevant tissues. Finally, we evaluated overlap between the genes/pathways identified here and those ascertained through larger aortic disease/trait genome-wide association studies. We show that SVAS severity in Williams-Beuren syndrome is associated with increased frequency of common and rarer variants in matrisome and immune pathways. Two implicated matrisome genes (ACAN and LTBP4) were uniquely expressed in the aorta. Many genes in the identified pathways were previously reported in genome-wide association studies for aneurysm, bicuspid aortic valve, or aortic size.

CONCLUSIONS

Smaller sample sizes in rare disease studies necessitate new approaches to detect modifiers. Our strategies identified variation in matrisome and immune pathways that are associated with SVAS severity. These findings suggest that, like other aortopathies, SVAS may be influenced by the balance of synthesis and degradation of matrisome proteins. Leveraging multiomic data and results from larger aorta-focused genome-wide association studies may accelerate modifier discovery for rare aortopathies like SVAS.

Increased Expression of Mevalonate Pathway-Related Enzymes in Angiotensin II-Induced Abdominal Aortic Aneurysms

Abdominal aortic aneurysm (AAA) is characterized by permanent luminal expansion and a high mortality rate due to aortic rupture. Despite the identification of abnormalities in the mevalonate pathway (MVA) in many diseases, including cardiovascular diseases, the potential impact of this pathway on AAA remains unclear. This study aims to investigate whether the expression of the MVA-related enzyme is altered during the progression of angiotensin II (Ang II) -induced AAA.Ang II 28D and Ang II 5D groups were continuously perfused with Ang II for 28 days and 5 days, respectively, and the Sham group was perfused with saline. The general and remodeling characteristics of AAA were determined by biochemical and histological analysis. Alteration of MVA-related enzyme expressions was revealed by western blot and single-cell RNA sequencing (scRNA-seq).The continuous Ang II infusion for 28 days showed significant aorta expansion and arterial remodeling. Although the arterial diameter slightly increased, the aneurysm formation was not found in Ang II induction for 5 days. MVA-related enzyme expression and activation of small GTP-binding proteins were significantly increased after Ang II-induced. As verified by scRNA-seq, the key enzyme gene expression was also higher in Ang II 28D. Similarly, it was detected that the expression levels of the above enzymes and the activity of small G proteins were elevated in the early stage of AAA as induced by Ang II infusion for 5 days.Continuous Ang II infusion-induced abdominal aortic expansion and arterial remodeling were accompanied by altered expression of key enzymes in the MVA.

Global research status analysis of the association between aortic aneurysm and inflammation: a bibliometric analysis from 1999 to 2023

Background

Aortic aneurysm is a chronic arterial disease that can lead to aortic rupture, causing severe complications and life-threatening risks for patients, and it is one of the common causes of death among the elderly. Increasing evidence suggests that inflammation plays an important role in the progression of aortic aneurysm. However, there is a lack of literature-based quantitative analysis in this field.

Methods

Up to March 30, 2023, we collected 3,993 articles related to aortic aneurysm and inflammation from the Web of Science Core Collection (WoSCC) database for bibliometric analysis. The collected literature data were subjected to visual analysis of regional distribution, institutions, authors, keywords, and other information using tools such as CiteSpace, VOSviewer, the R package "bibliometric," and online platforms.

Results

The number of publications in this research field has been steadily increasing each year, with the United States and China being the main contributing countries. Harvard University in the United States emerged as the most active and influential research institution in this field. Jonathan Golledge and Peter Libby were identified as the authors with the highest publication output and academic impact, respectively. Researchers in this field tend to publish their findings in influential journals such as the Journal of Vascular Surgery and Arteriosclerosis Thrombosis and Vascular Biology. "Abdominal aortic aneurysm," "giant cell arteritis," "arterial stiffness," and "smooth muscle cells" were identified as the hottest topics in the field of aortic aneurysm and inflammation. In terms of keyword co-occurrence analysis, "Clinical relevant studies of AA" (red), "Inflammatory activation" (green), "Inflammatory mechanisms related to pathogenesis" (dark blue), "Cytokines" (yellow), "Risk factors" (purple), and "Pathological changes in vascular wall" (cyan) formed the major research framework in this field. "Inflammation-related pathogenesis" and "inflammation activation" have emerged as recent hot research directions, with "monocytes," "progression," and "proliferation" being the prominent topics.

Conclusion

This study provides a comprehensive analysis of the knowledge network framework and research hotspots in the field of aortic aneurysm and inflammation through a literature-based quantitative approach. It offers valuable insights to guide scholars in identifying meaningful research directions in this field.

Tanshinone IIA: a Chinese herbal ingredient for the treatment of atherosclerosis

Tanshinone IIA (Tan IIA) is a fat-soluble compound extracted from Salvia miltiorrhiza, which has a protective effect against atherosclerosis (AS). Tan IIA can inhibit oxidative stress and inflammatory damage of vascular endothelial cells (VECs) and improve endothelial cell dysfunction. Tan IIA also has a good protective effect on vascular smooth muscle cells (VSMCs). It can reduce vascular stenosis by inhibiting the proliferation and migration of vascular smooth muscle cells (VSMCs), and improve the stability of the fibrous cap of atherosclerotic plaque by inhibiting apoptosis and inflammation of VSMCs. In addition, Tan IIA inhibits the inflammatory response of macrophages and the formation of foam cells in atherosclerotic plaques. In summary, Tan IIA improves AS through a complex pathway. We propose to further study the specific molecular targets of Tan IIA using systems biology methods, so as to fundamentally elucidate the mechanism of Tan IIA. It is worth mentioning that there is a lack of high-quality evidence-based medical data on Tan IIA treatment of AS. We recommend that a randomized controlled clinical trial be conducted to evaluate the exact efficacy of Tan IIA in improving AS. Finally, sodium tanshinone IIA sulfonate (STS) can cause adverse drug reactions in some patients, which needs our attention.

Antiplatelet Therapy, Abdominal Aortic Aneurysm Progression, and Clinical Outcomes

Importance

Preclinical studies suggest a potential role for aspirin in slowing abdominal aortic aneurysm (AAA) progression and preventing rupture. Evidence on the clinical benefit of aspirin in AAA from human studies is lacking.

Objective

To investigate the association of aspirin use with aneurysm progression and long-term clinical outcomes in patients with AAA.

Design, Setting, and Participants

This was a retrospective, single-center cohort study. Adult patients with at least 2 available vascular ultrasounds at the Cleveland Clinic were included, and patients with history of aneurysm repair, dissection, or rupture were excluded. All patients were followed up for 10 years. Data were analyzed from May 2022 to July 2023.

Main Outcomes and Measures

Clinical outcomes were time-to-first occurrence of all-cause mortality, major bleeding, or composite of dissection, rupture, and repair. Multivariable-adjusted Cox proportional-hazard regression was used to estimate hazard ratios (HR) for all-cause mortality, and subhazard ratios competing-risk regression using Fine and Gray proportional subhazards regression was used for major bleeding and composite outcome. Aneurysm progression was assessed by comparing the mean annualized change of aneurysm diameter using multivariable-adjusted linear regression and comparing the odds of having rapid progression (annual diameter change >0.5 cm per year) using logistic regression.

Results

A total of 3435 patients (mean [SD] age 73.7 [9.0] years; 2672 male patients [77.5%]; 120 Asian, Hispanic, American Indian, or Pacific Islander patients [3.4%]; 255 Black patients [7.4%]; 3060 White patients [89.0%]; and median [IQR] follow-up, 4.9 [2.5-7.5] years) were included in the final analyses, of which 2150 (63%) were verified to be taking aspirin by prescription. Patients taking aspirin had a slower mean (SD) annualized change in aneurysm diameter (2.8 [3.0] vs 3.8 [4.2] mm per year; P = .001) and lower odds of having rapid aneurysm progression compared with patients not taking aspirin (adjusted odds ratio, 0.64; 95% CI, 0.49-0.89; P = .002). Aspirin use was not associated with risk of all-cause mortality (adjusted HR [aHR], 0.92; 95% CI, 0.79-1.07; P = .32), nor was aspirin use associated with major bleeding (aHR, 0.88; 95% CI, 0.76-1.03; P = .12), or composite outcome (aHR, 1.16; 95% CI, 0.93-1.45; P = .09) at 10 years.

Conclusions

In this retrospective study of a clinical cohort of 3435 patients with objectively measured changes in aortic aneurysm growth, aspirin use was significantly associated with slower progression of AAA with a favorable safety profile.

Causal Role for Neutrophil Elastase in Thoracic Aortic Dissection in Mice

BACKGROUND

Thoracic aortic dissection (TAD) is a life-threatening aortic disease without effective medical treatment. Increasing evidence has suggested a role for NE (neutrophil elastase) in vascular diseases. In this study, we aimed at investigating a causal role for NE in TAD and exploring the molecular mechanisms involved.

METHODS

β-aminopropionitrile monofumarate was administrated in mice to induce TAD. NE deficiency mice, pharmacological inhibitor GW311616A, and adeno-associated virus-2-mediated in vivo gene transfer were applied to explore a causal role for NE and associated target gene in TAD formation. Multiple functional assays and biochemical analyses were conducted to unravel the underlying cellular and molecular mechanisms of NE in TAD.

RESULTS

NE aortic gene expression and plasma activity was significantly increased during β-aminopropionitrile monofumarate-induced TAD and in patients with acute TAD. NE deficiency prevents β-aminopropionitrile monofumarate-induced TAD onset/development, and GW311616A administration ameliorated TAD formation/progression. Decreased levels of neutrophil extracellular traps, inflammatory cells, and MMP (matrix metalloproteinase)-2/9 were observed in NE-deficient mice. TBL1x (F-box-like/WD repeat-containing protein TBL1x) has been identified as a novel substrate and functional downstream target of NE in TAD. Loss-of-function studies revealed that NE mediated inflammatory cell transendothelial migration by modulating TBL1x-LTA4H (leukotriene A4 hydrolase) signaling and that NE regulated smooth muscle cell phenotype modulation under TAD pathological condition by regulating TBL1x-MECP2 (methyl CpG-binding protein 2) signal axis. Further mechanistic studies showed that TBL1x inhibition decreased the binding of TBL1x and HDAC3 (histone deacetylase 3) to MECP2 and LTA4H gene promoters, respectively. Finally, adeno-associated virus-2-mediated Tbl1x gene knockdown in aortic smooth muscle cells confirmed a regulatory role for TBL1x in NE-mediated TAD formation.

CONCLUSIONS

We unravel a critical role of NE and its target TBL1x in regulating inflammatory cell migration and smooth muscle cell phenotype modulation in the context of TAD. Our findings suggest that the NE-TBL1x signal axis represents a valuable therapeutic for treating high-risk TAD patients.

C-reactive protein deficiency ameliorates experimental abdominal aortic aneurysms

Background

C-reactive protein (CRP) levels are elevated in patients with abdominal aortic aneurysms (AAA). However, it has not been investigated whether CRP contributes to AAA pathogenesis.

Methods

CRP deficient and wild type (WT) male mice were subjected to AAA induction via transient intra-aortic infusion of porcine pancreatic elastase. AAAs were monitored by in situ measurements of maximal infrarenal aortic external diameters immediately prior to and 14 days following elastase infusion. Key AAA pathologies were assessed by histochemical and immunohistochemical staining procedures. The influence of CRP deficiency on macrophage activation was evaluated in peritoneal macrophages in vitro.

Results

CRP protein levels were higher in aneurysmal than that in non-aneurysmal aortas. Aneurysmal aortic dilation was markedly suppressed in CRP deficient (aortic diameter: 1.08 ± 0.11 mm) as compared to WT (1.21 ± 0.08 mm) mice on day 14 after elastase infusion. More medial elastin was retained in CRP deficient than in WT elastase-infused mice. Macrophage accumulation was significantly less in aneurysmal aorta from CRP deficient than that from WT mice. Matrix metalloproteinase 2 expression was also attenuated in CRP deficient as compared to WT aneurysmal aortas. CRP deficiency had no recognizable influence on medial smooth muscle loss, lymphocyte accumulation, aneurysmal angiogenesis, and matrix metalloproteinase 9 expression. In in vitro assays, mRNA levels for tumor necrosis factor α and cyclooxygenase 2 were reduced in lipopolysaccharide activated peritoneal macrophages from CRP deficient as compared to wild type mice.

Conclusion

CRP deficiency suppressed experimental AAAs by attenuating aneurysmal elastin destruction, macrophage accumulation and matrix metalloproteinase 2 expression.

The inhibition of Wnt signaling attenuates RANKL-induced osteoclastogenic macrophage activation

Abdominal aortic aneurysms (AAAs) have been linked to the activation of osteoclastogenic macrophages. Reports have suggested that Wnt signaling has a dual effect of proliferation and differentiation during osteoclastogenesis. The Wnt/β-Catenin pathway is a critical regulator of cell pluripotency, cell survival, and cell fate decisions. It regulates cell proliferation and differentiation through transcriptional co-activators, CBP, and p300, respectively. The inhibition of β-catenin suppresses proliferation but induces differentiation of osteoclast precursor cells. This study aimed to examine the effect of ICG-001, a β-catenin/CBP-specific Wnt signaling inhibitor, on osteoclastogenesis by inhibiting proliferation without inducing differentiation. To induce osteoclastogenesis, RAW 264.7 macrophages were stimulated with a soluble receptor activator of NF-κB ligand (RANKL). The effect of Wnt signaling inhibition was examined by treating macrophages with or without ICG-001 during RANKL stimulation. The activation and differentiation of macrophages were examined through western blotting, quantitative PCR, and tartrate-resistant acid phosphate (TRAP) staining in vitro. The relative expression level of the nuclear factor of activated T-cells cytoplasmic 1 protein was significantly suppressed by ICG-001 treatment. The relative expression levels of mRNA of TRAP, cathepsin K, and matrix metalloproteinase-9 were significantly lower in the ICG-001-treated group. The number of TRAP-positive cells decreased in the ICG-001-treated group relative to the non-treated group. The inhibition of Wnt signaling pathway via ICG-001 suppressed osteoclastogenic macrophage activation. Our previous studies have shown the importance of osteoclastogenic macrophage activation in AAA. Further research to examine the therapeutic potential of ICG-001 on AAA is warranted.

Treatment With Small Molecule Inhibitors of Advanced Glycation End-Products Formation and Advanced Glycation End-Products-Mediated Collagen Cross-Linking Promotes Experimental Aortic Aneurysm Progression in Diabetic Mice

Background Although diabetes attenuates abdominal aortic aneurysms (AAAs), the mechanisms by which diabetes suppresses AAAs remain incompletely understood. Accumulation of advanced glycation end- (AGEs) reduces extracellular matrix (ECM) degradation in diabetes. Because ECM degradation is critical for AAA pathogenesis, we investigated whether AGEs mediate experimental AAA suppression in diabetes by blocking AGE formation or disrupting AGE-ECM cross-linking using small molecule inhibitors. Methods and Results Male C57BL/6J mice were treated with streptozotocin and intra-aortic elastase infusion to induce diabetes and experimental AAAs, respectively. Aminoguanidine (AGE formation inhibitor, 200 mg/kg), alagebrium (AGE-ECM cross-linking disrupter, 20 mg/kg), or vehicle was administered daily to mice from the last day following streptozotocin injection. AAAs were assessed via serial aortic diameter measurements, histopathology, and in vitro medial elastolysis assays. Treatment with aminoguanidine, not alagebrium, diminished AGEs in diabetic AAAs. Treatment with both inhibitors enhanced aortic enlargement in diabetic mice as compared with vehicle treatment. Neither enhanced AAA enlargement in nondiabetic mice. AAA enhancement in diabetic mice by aminoguanidine or alagebrium treatment promoted elastin degradation, smooth muscle cell depletion, mural macrophage accumulation, and neoangiogenesis without affecting matrix metalloproteinases, C-C motif chemokine ligand 2, or serum glucose concentration. Additionally, treatment with both inhibitors reversed suppression of diabetic aortic medial elastolysis by porcine pancreatic elastase in vitro. Conclusions Inhibiting AGE formation or AGE-ECM cross-linking enhances experimental AAAs in diabetes. These findings support the hypothesis that AGEs attenuate experimental AAAs in diabetes. These findings underscore the potential translational value of enhanced ECM cross-linking as an inhibitory strategy for early AAA disease.

Genetic deficiency of protein inhibitor of activated STAT3 suppresses experimental abdominal aortic aneurysms

Aim

Signal transducer and activator of transcription (STAT) signaling is critical for the pathogenesis of abdominal aortic aneurysms (AAAs). Though protein inhibitor of activated STAT3 (PIAS3) negatively modulates STAT3 activity, but its role in AAA disease remains undefined.

Method

AAAs were induced in PIAS3 deficient (PIAS3−/−) and wild type (PIAS3+/+) male mice via transient intra-aortic elastase infusion. AAAs were assessed by in situ measurements of infrarenal aortic external diameters prior to (day 0) and 14 days after elastase infusion. Characteristic aneurysmal pathologies were evaluated by histopathology.

Results

Fourteen days following elastase infusion, aneurysmal aortic diameter was reduced by an approximately 50% in PIAS3−/− as compared to PIAS3+/+ mice. On histological analyses, PIAS3−/− mice showed less medial elastin degradation (media score: 2.5) and smooth muscle cell loss (media score: 3.0) than those in PIAS3+/+ mice (media score: 4 for both elastin and SMC destruction). Aortic wall leukocyte accumulation including macrophages, CD4+ T cells, CD8+ T cells and B cells as well as mural neovessel formation were significantly reduced in PIAS3−/− as compared to PIAS3+/+ mice. Additionally, PIAS3 deficiency also downregulated the expression levels of matrix metalloproteinases 2 and 9 by 61% and 70%, respectively, in aneurysmal lesion.

Conclusion

PIAS3 deficiency ameliorated experimental AAAs in conjunction with reduced medial elastin degradation and smooth muscle cell depletion, mural leukocyte accumulation and angiogenesis.

Homeostatic, Non-Canonical Role of Macrophage Elastase in Vascular Integrity

BACKGROUND

Matrix metalloproteinase (MMP)-12 is highly expressed in abdominal aortic aneurysms and its elastolytic function has been implicated in the pathogenesis. This concept is challenged, however, by conflicting data. Here, we sought to revisit the role of MMP-12 in abdominal aortic aneurysm.

METHODS

Apoe^-/- and Mmp12^-/-/Apoe^-/- mice were infused with Ang II (angiotensin). Expression of neutrophil extracellular traps (NETs) markers and complement component 3 (C3) levels were evaluated by immunostaining in aortas of surviving animals. Plasma complement components were analyzed by immunoassay. The effects of a complement inhibitor, IgG-FH_1-5 (factor H-immunoglobulin G), and macrophage-specific MMP-12 deficiency on adverse aortic remodeling and death from rupture in Ang II-infused mice were determined.

RESULTS

Unexpectedly, death from aortic rupture was significantly higher in Mmp12^-/-/Apoe^-/- mice. This associated with more neutrophils, citrullinated histone H3 and neutrophil elastase, markers of NETs, and C3 levels in Mmp12^-/- aortas. These findings were recapitulated in additional models of abdominal aortic aneurysm. MMP-12 deficiency also led to more pronounced elastic laminae degradation and reduced collagen integrity. Higher plasma C5a in Mmp12^-/- mice pointed to complement overactivation. Treatment with IgG-FH_1-5 decreased aortic wall NETosis and reduced adverse aortic remodeling and death from rupture in Ang II-infused Mmp12^-/- mice. Finally, macrophage-specific MMP-12 deficiency recapitulated the effects of global MMP-12 deficiency on complement deposition and NETosis, as well as adverse aortic remodeling and death from rupture in Ang II-infused mice.

CONCLUSIONS

An MMP-12 deficiency/complement activation/NETosis pathway compromises aortic integrity, which predisposes to adverse vascular remodeling and abdominal aortic aneurysm rupture. Considering these new findings, the role of macrophage MMP-12 in vascular homeostasis demands re-evaluation of MMP-12 function in diverse settings.

Distinct Mechanisms of β-Arrestin-Biased Agonist and Blocker of AT1R in Preventing Aortic Aneurysm and Associated Mortality

BACKGROUND

Aortic aneurysm (AA) is a "silent killer" human disease with no effective treatment. Although the therapeutic potential of various pharmacological agents have been evaluated, there are no reports of β-arrestin-biased AT1R (angiotensin-II type-1 receptor) agonist (TRV027) used to prevent the progression of AA.

METHODS

We tested the hypothesis that TRV027 infusion in AngII (angiotensin II)-induced mouse model of AA prevents AA. High-fat-diet-fed ApoE (apolipoprotein E gene)-null mice were infused with AngII to induce AA and co-infused with TRV027 and a clinically used AT1R blocker Olmesartan to prevent AA. Aortas explanted from different ligand infusion groups were compared with assess different grades of AA or lack of AA.

RESULTS

AngII produced AA in ≈67% male mice with significant mortality associated with AA rupture. We observed ≈13% mortality due to aortic arch dissection without aneurysm in male mice. AngII-induced AA and mortality was prevented by co-infusion of TRV027 or Olmesartan, but through different mechanisms. In TRV027 co-infused mice aortic wall thickness, elastin content, new DNA, and protein synthesis were higher than untreated and Olmesartan co-infused mice. Co-infusion with both TRV027 and Olmesartan prevented endoplasmic reticulum stress, fibrosis, and vasomotor hyper responsiveness.

CONCLUSIONS

TRV027-engaged AT1R prevented AA and associated mortality by distinct molecular mechanisms compared with the AT1R blocker, Olmesartan. Developing novel β-arrestin-biased AT1R ligands may yield promising drugs to combat AA.

Angiotensin II Type 1 Receptor Blocker Prevents Abdominal Aortic Aneurysm Progression in Osteoprotegerin-Deficient Mice via Upregulation of Angiotensin (1-7)

Background Angiotensin II type 1 receptor blockers (ARBs) have been shown to limit the growth of abdominal aortic aneurysm (AAA), but their efficacy is controversial. This study aimed to investigate the molecular mechanism underlying the protective effect of ARBs against AAA progression. Methods and Results Olmesartan, an ARB, was administered to wild-type and osteoprotegerin-knockout (Opg-KO) mice starting 2 weeks before direct application of CaCl₂ to aortas to induce AAA. The protective effect of olmesartan against AAA in wild-type and Opg-KO mice was compared at 6 weeks after AAA induction. Olmesartan prevented AAA progression in Opg-KO mice, including excessive aortic dilatation and collapse of tunica media, but not in wild-type mice. Deficiency of the Opg gene is known to cause excessive activation of the tumor necrosis factor-related apoptosis-inducing ligand-induced c-Jun N-terminal kinase/matrix metalloproteinase 9 pathway, resulting in prolonged AAA progression. Olmesartan attenuated the upregulation of phosphorylated c-Jun N-terminal kinase and matrix metalloproteinase 9 expression in the aortic wall of Opg-KO mice. In cultured vascular smooth muscle cells, tumor necrosis factor-related apoptosis-inducing ligand-induced c-Jun N-terminal kinase phosphorylation and matrix metalloproteinase 9 expression were inhibited by angiotensin (1-7), the circulating levels of which are increased by ARBs. Furthermore, administering an angiotensin (1-7) antagonist to Opg-KO mice diminished the protective effect of olmesartan against AAA progression. Conclusions Olmesartan prevented AAA progression in Opg-KO mice by upregulating angiotensin (1-7), suggesting that angiotensin (1-7) may be a key factor that mediates the protective effect of ARBs.

Comparative analysis of thoracic and abdominal aortic aneurysms across the segment and species at the single-cell level

Introduction: Aortic aneurysm is a life-threatening disease resulted from progressive dilatation of the aorta, which can be subdivided into thoracic and abdominal aortic aneurysms. Sustained subcutaneous angiotensin II infusion can induce aortic aneurysms in mice. However, the relevance of using angiotensin II induction model to study aneurysm disease and the degree of commonality between species remain elusive. Methods: We utilized scRNA-seq to infer aortic cell sub-structures and transcriptional profiles in clinical patient TAAs and AAAs, as well as mouse models of corresponding diseases (Ang II induction) and in healthy mouse aorta. Unbiased comparison between mice and humans explored the possible reasonability and utility of mouse Ang II-induced aortic aneurysm as a model for human aortic aneurysm diseases. Meanwhile, we performed comparative analysis of aortic aneurysms between TAA and AAA in both organisms. Results and Discussion: We demonstrated similarities and differences of changes in the components of human and mouse cell types, and our unbiased comparison between mouse and human identified well conserved subpopulations of SMCs and macrophages. Furthermore, the results of our comparative analyses suggested different biological functions and distinct potential pathogenic genes for thoracic and abdominal aortic aneurysms. MIF and SPP1 signaling networks participated in aortic aneurysm in both organisms. This study maps aortic aneurysm and offers opportunities for future researches to investigate the potential of subpopulations or marker genes as therapy targets.

Global trends and Frontier topics about vascular smooth muscle cells phenotype switch: A bibliometric analysis from 1999 to 2021

Objective: Vascular smooth muscle cell phenotype switch (VSMCPS) plays a significant role in vascular remodeling. This study aimed to conduct a bibliometric analysis and visualize the knowledge map of research on VSMCPS. Methods: We retrieved publications focusing on VSMCPS from the Web of Science Core Collection database (SCI-EXPANDED) from 1999 to 2021. Using bibliometric tools, VOSviewer and CiteSpace, we identified the most productive researchers, journals, institutions, and countries. At the same time, the trends, hot topics, and knowledge networks were analyzed and visualized. Results: A total of 2213 publications were included in this analysis. The number of annual publications in the VSMCPS field exhibited an upward trend and could be roughly divided into three phases. Until 2006, the most prolific authors were from the United States. As of 2008, the number of articles published in China increased dramatically to reach 126 papers in 2020. As of 2014, China was the most productive country in this field. The United States ranked first in the number of highly-influential authors, institutions, and literature from 1999 to 2022. Owens GK, Hata, Akiko, and Wen, jin-kun were the most prolific authors. Arteriosclerosis Thrombosis and Vascular Biology, Circulation Research, and Cardiovascular Research were the top-ranked journals in this field. "Vascular remodeling," "atherosclerosis," "neointima," "hypertension", and "inflammation" were the main researched topics. New diseases, new mechanisms, and new phenotype (e.g., micro RNA, macrophage-like-cell, hypoxia, autophagy, long noncoding RNA, oxidative stress, endoplasmic reticulum stress, senescence, aging, abdominal aortic aneurysm, and aortic dissection) represent the trending topics in recent years. Conclusion: This study systematically analyzed and visualized the knowledge map of VSMCPS over the past 2 decades. Our findings provide a comprehensive overview for scholars who want to understand current trends and new research frontiers in this area.

Immune and inflammatory mechanisms of abdominal aortic aneurysm

Abdominal aortic aneurysm (AAA) is a life-threatening cardiovascular disease. Immune-mediated infiltration and a destruction of the aortic wall during AAA development plays significant role in the pathogenesis of this disease. While various immune cells had been found in AAA, the mechanisms of their activation and function are still far from being understood. A better understanding of mechanisms regulating the development of aberrant immune cell activation in AAA is essential for the development of novel preventive and therapeutic approaches. In this review we summarize current knowledge about the role of immune cells in AAA and discuss how pathogenic immune cell activation is regulated in this disease.

Triglyceride glucose index is independently associated with aortic intima-media thickness in patients without known atherosclerotic cardiovascular disease or diabetes

Background: The triglyceride-glucose (TyG) index is a reliable marker of insulin resistance. We aimed to investigate the relationship between the TyG index and aortic intima-media thickness (IMT) in individuals without diabetes mellitus and atherosclerotic cardiovascular disease undergoing transoesophageal echocardiography due to suspected structural heart disease.Methods: One hundred twenty-two patients enrolled in the study between January 2021 and June 2021. Patients were divided into two groups according to their median IMT; patients with an IMT equal to or less than 1.42 mm were low IMT group, and higher than 1.42 mm were high IMT group. Triglyceride-glucose index were higher in the high IMT group (8.69 ± 0.59 vs. 8.37 ± 0.53, p = .003).Results: Triglyceride-glucose index was correlated with IMT (r = 0.259, p = .005) and in binary logistic regression analysis age and TyG was independently associated with having high IMT (β = 0.076, exp(B)=1.079 95%CI = 1.041-1.118, p < .001 and β = 0.847, exp(B)= 2.334 95%CI= 1.048-5.199, p = .038, respectively).Conclusion: We found an independent relationship between TyG and IMT of the thoracic aorta, an early marker of subclinical atherosclerosis in patients without known atherosclerotic cardiovascular disease or diabetes. Therefore, the TyG index can identify high-risk subjects in the general population.

Edaravone Attenuated Angiotensin II-Induced Atherosclerosis and Abdominal Aortic Aneurysms in Apolipoprotein E-Deficient Mice

Background: The aim of the study was to define whether edaravone, a free-radical scavenger, influenced angiotensin II (AngII)-induced atherosclerosis and abdominal aortic aneurysms (AAAs) formation. Methods: Male apolipoprotein E-deficient mice (8–12 weeks old) were fed with a normal diet for 5 weeks. Either edaravone (10 mg/kg/day) or vehicle was injected intraperitoneally for 5 weeks. After 1 week of injections, mice were infused subcutaneously with either AngII (1000 ng/kg/min, n = 16–17 per group) or saline (n = 5 per group) by osmotic minipumps for 4 weeks. Results: AngII increased systolic blood pressure equivalently in mice administered with either edaravone or saline. Edaravone had no effect on plasma total cholesterol concentrations and body weights. AngII infusion significantly increased ex vivo maximal diameters of abdominal aortas and en face atherosclerosis but was significantly attenuated by edaravone administration. Edaravone also reduced the incidence of AngII-induced AAAs. In addition, edaravone diminished AngII-induced aortic MMP-2 activation. Quantitative RT-PCR revealed that edaravone ameliorated mRNA abundance of aortic MCP-1 and IL-1β. Immunostaining demonstrated that edaravone attenuated oxidative stress and macrophage accumulation in the aorta. Furthermore, edaravone administration suppressed thioglycolate-induced mice peritoneal macrophages (MPMs) accumulation and mRNA abundance of MCP-1 in MPMs in male apolipoprotein E-deficient mice. In vitro, edaravone reduced LPS-induced mRNA abundance of MCP-1 in MPMs. Conclusions: Edaravone attenuated AngII-induced AAAs and atherosclerosis in male apolipoprotein E-deficient mice via anti-oxidative action and anti-inflammatory effect.

Peptide-siRNA nanoparticles targeting NF-κB p50 mitigate experimental abdominal aortic aneurysm progression and rupture

Abdominal aortic aneurysm (AAA) is a progressive vascular condition associated with high risk of mortality if left untreated. AAA is an inflammatory process with excessive local production of extracellular matrix degrading enzymes, leading to dilatation and rupture of the abdominal aorta. We posit that targeting NF-κB, a signaling pathway that controls inflammation, will halt AAA progression and prevent rupture. In an elastase-induced AAA model we observed that NF-κB activation increased progressively post-elastase perfusion. Unexpectedly, we found that AAA progression was marked by predominant nuclear accumulation of the NF-κB p50 subunit at the exclusion of p65. Using the amphipathic peptide p5RHH to form nanocomplexes with siRNA, we sought to mitigate AAA progression by knocking down the expression of different NF-κB subunits. We found that the administration of NF-κB p65 siRNA was only beneficial when given early (day 3 post-elastase perfusion) while p50 siRNA was still effective in mitigating elastase-induced AAA even when delivery was delayed until day 5. Additionally, systemic delivery of p50 siRNA, but not p65 siRNA decreased the risk of aortic rupture and sudden death in the transforming growth factor-beta blockade model of AAA. In both murine models, knockdown of NF-κB was accompanied by a significant decrease in leukocyte infiltrates, inflammatory cytokine release, inducible nitric oxide synthase expression, and cell apoptosis. These results suggest that the NF-κB p50 and p65 subunits contribute differentially at different stages of disease and the timing of in vivo siRNA delivery was of critical importance. The results also provide a rationale for selective targeting of p50 for more specific therapeutic intervention in the medical treatment of small AAA.

Pemafibrate Prevents Rupture of Angiotensin II-Induced Abdominal Aortic Aneurysms

Background

Abdominal aortic aneurysm (AAA) is a life-threatening disease that lacks effective preventive therapies. This study aimed to evaluate the effect of pemafibrate, a selective peroxisome proliferator-activated receptor alpha (PPARα) agonist, on AAA formation and rupture.

Methods

Experimental AAA was induced by subcutaneous angiotensin II (AngII) infusion in ApoE ^{- / -} mice for 4 weeks. Pemafibrate (0.1 mg/kg/day) was administered orally. Dihydroethidium staining was used to evaluate the reactive oxygen species (ROS).

Results

The size of the AngII-induced AAA did not differ between pemafibrate- and vehicle-treated groups. However, a decreased mortality rate due to AAA rupture was observed in pemafibrate-treated mice. Pemafibrate ameliorated AngII-induced ROS and reduced the mRNA expression of interleukin-6 and tumor necrosis factor-α in the aortic wall. Gelatin zymography analysis demonstrated significant inhibition of matrix metalloproteinase-2 activity by pemafibrate. AngII-induced ROS production in human vascular smooth muscle cells was inhibited by pre-treatment with pemafibrate and was accompanied by an increase in catalase activity. Small interfering RNA-mediated knockdown of catalase or PPARα significantly attenuated the anti-oxidative effect of pemafibrate.

Conclusion

Pemafibrate prevented AAA rupture in a murine model, concomitant with reduced ROS, inflammation, and extracellular matrix degradation in the aortic wall. The protective effect against AAA rupture was partly mediated by the anti-oxidative effect of catalase induced by pemafibrate in the smooth muscle cells.

Peptide Amphiphile Supramolecular Nanofibers Designed to Target Abdominal Aortic Aneurysms

An abdominal aortic aneurysm (AAA) is a localized dilation of the aorta located in the abdomen that poses a severe risk of death when ruptured. The cause of AAA is not fully understood, but degradation of medial elastin due to elastolytic matrix metalloproteinases is a key step leading to aortic dilation. Current therapeutic interventions are limited to surgical repair to prevent catastrophic rupture. Here, we report the development of injectable supramolecular nanofibers using peptide amphiphile molecules designed to localize to AAA by targeting fragmented elastin, matrix metalloproteinase 2 (MMP-2), and membrane type 1 matrix metalloproteinase. We designed four targeting peptide sequences from X-ray crystallographic data and incorporated them into PA molecules via solid phase peptide synthesis. After coassembling targeted and diluent PAs at different molar ratios, we assessed their ability to form nanofibers using transmission electron microscopy and to localize to AAA in male and female Sprague-Dawley rats using light sheet fluorescence microscopy. We found that three formulations of the PA nanofibers were able to localize to AAA tissue, but the MMP-2 targeting PA substantially outperformed the other nanofibers. Additionally, we demonstrated that the MMP-2 targeting PA nanofibers had an optimal dose of 5 mg (∼12 mg/kg). Our results show that there was not a significant difference in targeting between male and female Sprague-Dawley rats. Given the ability of the MMP-2 targeting PA nanofiber to localize to AAA tissue, future studies will investigate potential diagnostic and targeted drug delivery applications for AAA.

Twenty Years of Studying AngII (Angiotensin II)-Induced Abdominal Aortic Pathologies in Mice: Continuing Questions and Challenges to Provide Insight Into the Human Disease

AngII (angiotensin II) infusion in mice has been used to provide mechanistic insight into human abdominal aortic aneurysms for over 2 decades. This is a technically facile animal model that recapitulates multiple facets of the human disease. Although numerous publications have reported abdominal aortic aneurysms with AngII infusion in mice, there remain many fundamental unanswered questions such as uniformity of describing the pathological characteristics and which cell type is stimulated by AngII to promote abdominal aortic aneurysms. Extrapolation of the findings to provide insight into the human disease has been hindered by the preponderance of studies designed to determine the effects on initiation of abdominal aortic aneurysms, rather than a more clinically relevant scenario of determining efficacy on the established disease. The purpose of this review is to enhance understanding of AngII-induced abdominal aortic pathologies in mice, thereby providing greater insight into the human disease.

Collagen-associated side effects of fluoroquinolones: aneurysm and aortic dissection (systematic review)

Well known for fluoroquinolones cause the development of collagen-associated side effects tendopathies with the risk of tendon rupture and retinal detachment, which is associated with the damaging effect and degradation of type I and type III collagen. The aorta is also rich in collagen type I and type III up to 8090%, which has the potential to play a role in the development of aortopathies in cases of fluoroquinolone use. Since 2015, the first publications of research results on the collagen-associated effect of fluoroquinolones on the development of aneurysm and aortic dissection, often called aortopathy, began to appear. A systematic review of observational studies and 5 meta-analyzes of the development of a novel side effect of fluoroquinolones is presented. An absolute incidence of this side effect of 1.1% and a twofold increased relative risk of developing aneurysm/aortic dissection (RR 2.042.23), aortic aneurysm (RR 1.742.83), and aortic dissection (RR 1.882.79). When analyzing age subgroups, an increase in the risk of aneurysm/aortic dissection was noted already from the age of 35 years and was more significant in elderly patients (over 65 years). Analisys of the course duration of fluoroquinolone use (314 days or 14 days) was carried out in two studies and showed an increase in the risk of aneurysm/aortic dissection with increasing duration of fluoroquinolone therapy (RR 1.72 versus RR 1.92). The risk of developing a fluoroquinolone-associated aortopathy was highest during the first 30 days after the course use of fluoroquinolones, with a slight decrease within 6090 days after the course. The signal was confirmed by the FDA pharmacovigilance system (USA) during the analysis of cases of aneurysm/aortic dissection against the background of fluoroquinolones use. International regulatory authorities (FDA and EMA) have announced official documents warning of an increased incidence of rare but serious cases of aortic dissection or ruptured aortic aneurysm with oral fluoroquinolones. Fluoroquinolones should not be given to patients at increased risk unless other treatment options are available. The increased risk category includes patients with a history of aortic or other blood vessel aneurysm, high blood pressure, and the elderly.

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.

Chronic Intermittent Hypoxia Regulates CaMKII-Dependent MAPK Signaling to Promote the Initiation of Abdominal Aortic Aneurysm

Obstructive sleep apnea (OSA) is highly prevalent in patients with abdominal aortic aneurysm (AAA). However, the effects of OSA on AAA initiation in a murine model of sleep apnea have not been completely studied. In this paper, Apoe^−/− C57BL/6 mice infused with angiotensin II (Ang II) were placed in chronic intermittent hypoxia (CIH) condition for inducing OSA-related AAA. CIH significantly promoted the incidence of AAA and inhibited the survival of mice. By performing ultrasonography and elastic Van Gieson staining, CIH was found to be effective in promoting aortic dilation and elastin degradation. Immunohistochemical and zymography results show that CIH upregulated the expression and activity of MMP2 and MMP9 and upregulated MCP1 expression while downregulating α-SMA expression. Also, CIH exposure promoted ROS generation, apoptosis, and mitochondria damage in vascular smooth muscle cells (VSMCs), which were measured by ROS assay, TUNEL staining, and transmission electron microscopy. The result of RNA sequencing of mouse aortas displayed that 232 mRNAs were differently expressed between Ang II and Ang II+CIH groups, and CaMKII-dependent p38/Jnk was confirmed as one downstream signaling of CIH. CaMKII-IN-1, an inhibitor of CaMKII, eliminated the effects of CIH on the loss of primary VSMCs. To conclude, a mouse model of OSA-related AAA, which contains the phenotypes of both AAA and OSA, was established in this study. We suggested CIH as a risk factor of AAA initiation through CaMKII-dependent MAPK signaling.

Lnc-C2orf63-4-1 Confers VSMC Homeostasis and Prevents Aortic Dissection Formation via STAT3 Interaction

Emerging evidence indicates that long non-coding RNAs (lncRNAs) serve as a critical molecular regulator in various cardiovascular diseases. Here, we aimed to identify and functionally characterize lncRNAs as potential mediators in the development of thoracic aortic dissection (TAD). We identified that a novel lncRNA, lnc-C2orf63-4-1, was lowly expressed in aortic samples of TAD patients and angiotensin II (Ang II)-challenged vascular smooth muscle cells (VSMCs), which was correlated with clinically aortic expansion. Besides, overexpression of lnc-C2orf63-4-1 significantly attenuated Ang II-induced apoptosis, phenotypic switching of VSMCs and degradation of extracellular matrix both in vitro and in vivo. A customized transcription factor array identified that signal transducer and activator of transcription 3 (STAT3) functioned as the main downstream effector. Mechanistically, dual-luciferase report analysis and RNA antisense purification (RAP) assay indicated that lnc-C2orf63-4-1 directly decreased the expression of STAT3, which was depend on the reduced stabilization of STAT3 mRNA. Importantly, up-regulation of STAT3 efficiently reversed the protective role of lnc-C2orf63-4-1 against Ang II-mediated vascular remodeling. Therefore, lnc-C2orf63-4-1 negatively regulated the expression of STAT3 and prevented the development of aortic dissection. Our study revealed that lnc-C2orf63-4-1 played a critical role in vascular homeostasis, and its dysfunction exacerbated Ang II-induced pathological vascular remodeling.

Plasma Big Endothelin-1 Level Predicted 5-Year Major Adverse Cardiovascular Events in Patients With Coronary Artery Ectasia

Background: Coronary artery ectasia (CAE) is found in about 1% of coronary angiography and is associated with poor clinical outcomes. The prognostic value of plasma big Endothelin-1 (ET-1) in CAE remains unknown. Methods: Patients with angiographically confirmed CAE from 2009 to 2015, who had big ET-1 data available were included. The primary outcome was 5-year major adverse cardiovascular events (MACE), defined as a component of cardiovascular death and non-fatal myocardial infarction (MI). Patients were divided into high or low big ET-1 groups using a cut-off value of 0.58 pmol/L, according to the receiver operating characteristic curve. Kaplan-Meier method, propensity score method, and Cox regression were used to assess the clinical outcomes in the 2 groups. Results: A total of 992 patients were included, with 260 in the high big ET-1 group and 732 in the low big ET-1 group. At 5-year follow-up, 57 MACEs were observed. Kaplan-Meier analysis and univariable Cox regression showed that patients with high big ET-1 levels were at increased risk of MACE (9.87 vs. 4.50%; HR 2.23, 95% CI 1.32-3.78, P = 0.003), cardiovascular death (4.01 vs. 1.69%; HR 2.37, 95% CI 1.02-5.48, P = 0.044), and non-fatal MI (6.09 vs. 2.84%; HR 2.17, 95% CI 1.11-4.24, P = 0.023). A higher risk of MACE in the high big ET-1 group was consistent in the propensity score matched cohort and propensity score weighted analysis. In multivariable analysis, a high plasma big ET-1 level was still an independent predictor of MACE (HR 1.82, 95% CI 1.02-3.25, P = 0.043). A combination of high plasma big ET-1 concentrate and diffuse dilation, when used to predict 5-year MACE risk, yielded a C-statistic of 0.67 (95% CI 0.59-0.74). Conclusion: Among patients with CAE, high plasma big ET-1 level was associated with increased risk of MACE, a finding that could improve risk stratification.

Receptor Interacting Protein Kinases 1/3: The Potential Therapeutic Target for Cardiovascular Inflammatory Diseases

The receptor interacting protein kinases 1/3 (RIPK1/3) have emerged as the key mediators in cell death pathways and inflammatory signaling, whose ubiquitination, phosphorylation, and inhibition could regulate the necroptosis and apoptosis effectually. Recently, more and more studies show great interest in the mechanisms and the regulator of RIPK1/3-mediated inflammatory response and in the physiopathogenesis of cardiovascular diseases. The crosstalk of autophagy and necroptosis in cardiomyocyte death is a nonnegligible conversation of cell death. We elaborated on RIPK1/3-mediated necroptosis, pathways involved, the latest regulatory molecules and therapeutic targets in terms of ischemia reperfusion, myocardial remodeling, myocarditis, atherosclerosis, abdominal aortic aneurysm, and cardiovascular transplantation, etc.

Temporal and Quantitative Analysis of Aortic Immunopathologies in Elastase-Induced Mouse Abdominal Aortic Aneurysms

Objective

Elastase-induced abdominal aortic aneurysm (AAA) model is widely used for aneurysmal pathogenesis and translational research. However, temporal alternations in aneurysmal histologies remain unknown. This study is aimed at analyzing temporal immunopathologies of aneurysmal aorta following experimental AAA induction.

Methods

Male C57BL/6J mice at the age of 10-14 weeks received intra-aortic infusion of elastase to induce AAAs. Aortic diameters at the baseline and indicated days after AAA induction were measured, and aortae were collected for histopathological analysis.

Results

Aorta diameters increased from 0.52 mm at the baseline levels to 0.99 mm, 1.34 mm, and 1.41 mm at days 7, 14, and 28, respectively, corresponding 90%, 158%, and 171% increases over the baseline level. Average aortic diameters did not differ between days 14 and 28. Severe elastin degradation and smooth muscle cell depletion were found at days 14 and 28 as compared to the baseline and day 7. No difference in the scores of medial elastin and SMC destruction was noted between days 14 and 28. Consistent results were found for leukocyte accumulation, neoangiogenesis, and matrix metalloproteinase expression. Twenty-eight days after AAA induction, all aneurysmal pathologies showed an attenuated trend, although most histopathological parameters did no differ between days 14 and 28.

Conclusion

Our data suggest that almost aneurysmal immunohistopathologies reach maximal 14 days following AAA induction. Analysis of day 14 histologies is sufficient for AAA pathogenesis and translational studies in elastase-induced mouse experimental AAAs.

MFAP4 Deficiency Attenuates Angiotensin II-Induced Abdominal Aortic Aneurysm Formation Through Regulation of Macrophage Infiltration and Activity

Objective: Abdominal aortic aneurysm (AAA) is a common age-related vascular disease characterized by progressive weakening and dilatation of the aortic wall. Microfibrillar-associated protein 4 (MFAP4) is an extracellular matrix (ECM) protein involved in the induction of vascular remodeling. This study aimed to investigate if MFAP4 facilitates the development of AAA and characterize the underlying MFAP4-mediated mechanisms.

Approach and Results: Double apolipoprotein E- and Mfap4-deficient (ApoE^−/−Mfap4^−/−) and control apolipoprotein E-deficient (ApoE^−/−) mice were infused subcutaneously with angiotensin II (Ang II) for 28 days. Mfap4 expression was localized within the adventitial and medial layers and was upregulated after Ang II treatment. While Ang II-induced blood pressure increase was independent of Mfap4 genotype, ApoE^−/−Mfap4^−/− mice exhibited significantly lower AAA incidence and reduced maximal aortic diameter compared to ApoE^−/− littermates. The ApoE^−/−Mfap4^−/− AAAs were further characterized by reduced macrophage infiltration, matrix metalloproteinase (MMP)-2 and MMP-9 activity, proliferative activity, collagen content, and elastic membrane disruption. MFAP4 deficiency also attenuated activation of integrin- and TGF-β-related signaling within the adventitial layer of AAA tissues. Finally, MFAP4 stimulation promoted human monocyte migration and significantly upregulated MMP-9 activity in macrophage-like THP-1 cells.

Conclusion: This study demonstrates that MFAP4 induces macrophage-rich inflammation, MMP activity, and maladaptive remodeling of the ECM within the vessel wall, leading to an acceleration of AAA development and progression. Collectively, our findings suggest that MFAP4 is an essential aggravator of AAA pathology that acts through regulation of monocyte influx and MMP production.

Ginsenoside Rb1 Ameliorates Diabetic Arterial Stiffening via AMPK Pathway

Background and Purpose: Macrovascular complication of diabetes mellitus, characterized by increased aortic stiffness, is a major cause leading to many adverse clinical outcomes. It has been reported that ginsenoside Rb1 (Rb1) can improve glucose tolerance, enhance insulin activity, and restore the impaired endothelial functions in animal models. The aim of this study was to explore whether Rb1 could alleviate the pathophysiological process of arterial stiffening in diabetes and its potential mechanisms. Experimental Approach: Diabetes was induced in male C57BL/6 mice by administration of streptozotocin. These mice were randomly selected for treatment with Rb1 (10-60 mg/kg, i. p.) once daily for 8 weeks. Aortic stiffness was assessed using ultrasound and measurement of blood pressure and relaxant responses in the aortic rings. Mechanisms of Rb1 treatment were studied in MOVAS-1 VSMCs cultured in a high-glucose medium. Key Results: Rb1 improved DM-induced arterial stiffening and the impaired aortic compliance and endothelium-dependent vasodilation. Rb1 ameliorated DM-induced aortic remodeling characterized by collagen deposition and elastic fibers disorder. MMP2, MMP9, and TGFβ1/Smad2/3 pathways were involved in this process. In addition, Rb1-mediated improvement of arterial stiffness was partly achieved via inhibiting oxidative stress in DM mice, involving regulating NADPH oxidase. Finally, Rb1 could blunt the inhibition effects of DM on AMPK phosphorylation. Conclusion and Implications: Rb1 may represent a novel prevention strategy to alleviate collagen deposition and degradation to prevent diabetic macroangiopathy and diabetes-related complications.

A Novel Mechanism Underlying Inflammatory Smooth Muscle Phenotype in Abdominal Aortic Aneurysm

[Figure: see text].

Transglutaminase 2 moderates the expansion of mouse abdominal aortic aneurysms

Objective

Previously published work has indicated that transcripts encoding transglutaminase 2 (TG2) increase markedly in a rat model of abdominal aortic aneurysm. This study determines whether TG2 and the related TG, factor XIII-A (FXIII-A), protect against aortic aneurysm development in mice.

Methods

C57BL/6J wild-type, Tgm2 ^-/- knockout, F13a1 ^-/- knockout, and Tgm2 ^-/- /F13a1 ^-/- double knockout mice were subjected to laparotomy and periaortic application of CaCl₂.

Results

Tgm2 ^-/- mice showed slightly greater aortic dilatation at 6 weeks after treatment when compared with wild type. However, vessels from Tgm2 ^-/- mice, but not wild-type mice, continued to dilate up to 6 months after injury and by 24 weeks, a greater number of Tgm2 ^-/- mice had developed aneurysms (16/17 vs 10/19; P = .008). Laparotomy resulted in a high death rate in F13a1 ^-/- knockout mice, more frequently from cardiac complications than from hemorrhage, but among F13a1 ^-/- mice that survived for 6 weeks after CaCl₂ treatment, abdominal aortic aneurysm diameter was unaltered relative to wild-type mice. Laparotomy resulted in a higher death rate among Tgm2 ^-/- /F13a1 ^-/- double knockout mice, owing to an increased frequency of delayed bleeding. Surprisingly, Tgm2 ^-/- /F13a1 ^-/- double knockout mice showed a trend toward decreased dilatation of the aorta 6 weeks after injury, and this finding was replicated in Tgm2 ^-/- /F13a1 ^-/- mice subjected to carotid artery injury. Levels of transcripts encoding TG2 were not increased in the aortas of injured wild-type or F13a1 ^-/- knockout mice relative to uninjured mice, although changes in the levels of other transcripts accorded with previous descriptions of the CaCl₂ aneurysm model in mice.

Conclusions

Knockout of Tgm2, but not F13a1 exacerbates aortic dilatation, suggesting that TG2 confers protection. However, levels of TG2 messenger RNA are not acutely elevated after injury. FXIII-A plays a role in preventing postoperative damage after laparotomy, confirming previous reports that it prevents distal organ damage after trauma. TG2 promotes wound healing after surgery and, in its absence, the bleeding diathesis associated with FXIII-A deficiency is further exposed.

Lysyl hydroxylase 1 (LH1) deficiency promotes angiotensin II (Ang II)-induced dissecting abdominal aortic aneurysm

Rationale: The progressive disruption of extracellular matrix (ECM) proteins, particularly early elastin fragmentation followed by abnormalities in collagen fibril organization, are key pathological processes that contribute to dissecting abdominal aortic aneurysm (AAA) pathogenesis. Lysyl hydroxylase 1 (LH1) is essential for type I/III collagen intermolecular crosslinking and stabilization. However, its function in dissecting AAA has not been explored. Here, we investigated whether LH1 is significantly implicated in dissecting AAA progression and therapeutic intervention. Methods and Results: Sixteen-week-old male LH1-deficient and wild-type (WT) mice on the C57Bl/6NCrl background were infused with angiotensin II (Ang II, 1000 ng/kg per minute) via subcutaneously implanted osmotic pumps for 4 weeks. Ang II increased LH1 levels in the abdominal aortas of WT mice, whereas mice lacking LH1 developed dissecting AAA. To evaluate the related mechanism, we performed whole-transcriptomic analysis, which demonstrated that LH1 deficiency aggravated gene transcription alterations; in particular, the expression of thrombospondin-1 was markedly upregulated in the aortas of LH1-deficient mice. Furthermore, targeting thrombospondin-1 with TAX2 strongly inhibited the proinflammatory process, matrix metalloproteinase (MMP) activity and vascular smooth muscle cells (VSMCs) apoptosis, ultimately decreasing the incidence of dissecting AAA. Restoration of LH1 protein expression in LH1-deficient mice by intraperitoneal injection of an adeno-associated virus normalized thrombospondin-1 levels, subsequently alleviating dissecting AAA formation and preserving aortic structure and function. Consistently, in human AAA specimens, decreased LH1 expression was associated with increased thrombospondin-1 levels. Conclusions: LH1 deficiency contributes to dissecting AAA pathogenesis, at least in part, by upregulating thrombospondin-1 expression, which subsequently enables proinflammatory processes, MMP activation and VSMCs apoptosis. Our study provides evidence that LH1 is a potential critical therapeutic target for AAA.

Involvement of Angiogenesis in the Pathogenesis of Coronary Aneurysms

The present study aimed to evaluate the plasma concentration of pro and antiangiogenic factors and their role in the pathogenesis of coronary artery abnormal dilation (CAAD). We measured the plasma concentration of matrix metalloproteinase-8 (MMP-8), transforming growth factor beta 1 (TGF-β1), Angiopoietin-2, vascular endothelial growth factor (VEGF), and fibroblast growth factor (FGF) using a sandwich ELISA technique in the plasma of patients with coronary artery abnormal dilation (CAAD, Group 1), coronary artery disease (CAD, Group 2), and normal coronary arteries (NCA, Group 3). Patients suffering from CAAD showed significantly higher plasma concentrations of VEGF (p = 0.002) than those from the control group. Both pathological angiogenesis and inflammation appear to be crucial in the pathogenesis of aneurysmal dilatation of the coronary arteries.

Neutrophils as Regulators and Biomarkers of Cardiovascular Inflammation in the Context of Abdominal Aortic Aneurysms

Neutrophils represent up to 70% of circulating leukocytes in healthy humans and combat infection mostly by phagocytosis, degranulation and NETosis. It has been reported that neutrophils are centrally involved in abdominal aortic aneurysm (AAA) pathogenesis. The natural course of AAA is growth and rupture, if left undiagnosed or untreated. The rupture of AAA has a very high mortality and is currently among the leading causes of death worldwide. The use of noninvasive cardiovascular imaging techniques for patient screening, surveillance and postoperative follow-up is well established and recommended by the current guidelines. Neutrophil-derived biomarkers may offer clinical value to the monitoring and prognosis of AAA patients, allowing for potential early therapeutic intervention. Numerous promising biomarkers have been studied. In this review, we discuss neutrophils and neutrophil-derived molecules as regulators and biomarkers of AAA, and our aim was to specifically highlight diagnostic and prognostic markers. Neutrophil-derived biomarkers may potentially, in the future, assist in determining AAA presence, predict size, expansion rate, rupture risk, and postoperative outcome once validated in highly warranted future prospective clinical studies.

Smoking and the Pathophysiology of Peripheral Artery Disease

Smoking is one of the most important preventable factors causing peripheral artery disease (PAD). The purpose of this review is to comprehensively analyze and summarize the pathogenesis and clinical characteristics of smoking in PAD based on existing clinical, in vivo, and in vitro studies. Extensive searches and literature reviews have shown that a large amount of data exists on the pathological process underlying the effects of cigarette smoke and its components on PAD through various mechanisms. Cigarette smoke extracts (CSE) induce endothelial cell dysfunction, smooth muscle cell remodeling and macrophage phenotypic transformation through multiple molecular mechanisms. These pathological changes are the molecular basis for the occurrence and development of peripheral vascular diseases. With few discussions on the topic, we will summarize recent insights into the effect of smoking on regulating PAD through multiple pathways and its possible pathogenic mechanism.

TREM-1 orchestrates angiotensin II-induced monocyte trafficking and promotes experimental abdominal aortic aneurysm

The triggering receptor expressed on myeloid cells 1 (TREM-1) drives inflammatory responses in several cardiovascular diseases but its role in abdominal aortic aneurysm (AAA) remains unknown. Our objective was to explore the role of TREM-1 in a mouse model of angiotensin II-induced (AngII-induced) AAA. TREM-1 expression was detected in mouse aortic aneurysm and colocalized with macrophages. Trem1 gene deletion (Apoe-/-Trem1-/-), as well as TREM-1 pharmacological blockade with LR-12 peptide, limited both AAA development and severity. Trem1 gene deletion attenuated the inflammatory response in the aorta, with a reduction of Il1b, Tnfa, Mmp2, and Mmp9 mRNA expression, and led to a decreased macrophage content due to a reduction of Ly6Chi classical monocyte trafficking. Conversely, antibody-mediated TREM-1 stimulation exacerbated Ly6Chi monocyte aorta infiltration after AngII infusion through CD62L upregulation and promoted proinflammatory signature in the aorta, resulting in worsening AAA severity. AngII infusion stimulated TREM-1 expression and activation on Ly6Chi monocytes through AngII receptor type I (AT1R). In human AAA, TREM-1 was detected and TREM1 mRNA expression correlated with SELL mRNA expression. Finally, circulating levels of sTREM-1 were increased in patients with AAA when compared with patients without AAA. In conclusion, TREM-1 is involved in AAA pathophysiology and may represent a promising therapeutic target in humans.

Oxidative Stress-Related Susceptibility to Aneurysm in Marfan's Syndrome

The involvement of highly reactive oxygen-derived free radicals (ROS) in the genesis and progression of various cardiovascular diseases, including arrhythmias, aortic dilatation, aortic dissection, left ventricular hypertrophy, coronary arterial disease and congestive heart failure, is well-established. It has also been suggested that ROS may play a role in aortic aneurysm formation in patients with Marfan's syndrome (MFS). This syndrome is a multisystem disorder with manifestations including cardiovascular, skeletal, pulmonary and ocular systems, however, aortic aneurysm and dissection are still the most life-threatening manifestations of MFS. In this review, we will concentrate on the impact of oxidative stress on aneurysm formation in patients with MFS as well as on possible beneficial effects of some agents with antioxidant properties. Mechanisms responsible for oxidative stress in the MFS model involve a decreased expression of superoxide dismutase (SOD) as well as enhanced expression of NAD(P)H oxidase, inducible nitric oxide synthase (iNOS) and xanthine oxidase. The results of studies have indicated that reactive oxygen species may be involved in smooth muscle cell phenotype switching and apoptosis as well as matrix metalloproteinase activation, resulting in extracellular matrix (ECM) remodeling. The progression of the thoracic aortic aneurysm was suggested to be associated with markedly impaired aortic contractile function and decreased nitric oxide-mediated endothelial-dependent relaxation.

Maternal High-Fat Diet Promotes Abdominal Aortic Aneurysm Expansion in Adult Offspring by Epigenetic Regulation of IRF8-Mediated Osteoclast-like Macrophage Differentiation

Maternal high-fat diet (HFD) modulates vascular remodeling in adult offspring. Here, we investigated the impact of maternal HFD on abdominal aortic aneurysm (AAA) development. Female wild-type mice were fed an HFD or normal diet (ND). AAA was induced in eight-week-old pups using calcium chloride. Male offspring of HFD-fed dams (O-HFD) showed a significant enlargement in AAA compared with the offspring of ND-fed dams (O-ND). Positive-staining cells for tartrate-resistant acid phosphate (TRAP) and matrix metalloproteinase (MMP) activity were significantly increased in O-HFD. The pharmacological inhibition of osteoclastogenesis abolished the exaggerated AAA development in O-HFD. The in vitro tumor necrosis factor-α-induced osteoclast-like differentiation of bone marrow-derived macrophages showed a higher number of TRAP-positive cells and osteoclast-specific gene expressions in O-HFD. Consistent with an increased expression of nuclear factor of activated T cells 1 (NFATc1) in O-HFD, the nuclear protein expression of interferon regulatory factor 8 (IRF8), a transcriptional repressor, were much lower, with significantly increased H3K27me3 marks at the promoter region. The enhancer of zeste homolog 2 inhibitor treatment restored IRF8 expression, resulting in no difference in NFATc1 and TRAP expressions between the two groups. Our findings demonstrate that maternal HFD augments AAA expansion, accompanied by exaggerated osteoclast-like macrophage accumulation, suggesting the possibility of macrophage skewing via epigenetic reprogramming.

Sex Differences in Inflammation During Venous Remodeling of Arteriovenous Fistulae

Vascular disorders frequently have differing clinical presentations among women and men. Sex differences exist in vascular access for hemodialysis; women have reduced rates of arteriovenous fistula (AVF) maturation as well as fistula utilization compared with men. Inflammation is increasingly implicated in both clinical studies and animal models as a potent mechanism driving AVF maturation, especially in vessel dilation and wall thickening, that allows venous remodeling to the fistula environment to support hemodialysis. Sex differences have long been recognized in arterial remodeling and diseases, with men having increased cardiovascular events compared with pre-menopausal women. Many of these arterial diseases are driven by inflammation that is similar to the inflammation during AVF maturation. Improved understanding of sex differences in inflammation during vascular remodeling may suggest sex-specific vascular therapies to improve AVF success.

Crucial role of hematopoietic JAK2 V617F in the development of aortic aneurysms

JAK2 V617F is the most frequent driver mutation in myeloproliferative neoplasms (MPN) and is associated with vascular complications. However, the impact of hematopoietic JAK2 V617F on aortic aneurysms (AA) remains unknown. Our cross-sectional study indicated that nine (23%) of 39 MPN patients with JAK2 V617F exhibited the presence of AA. In order to clarify whether the hematopoietic JAK2 V617F contributes to the AA, we applied bone marrow transplantation (BMT) with the donor cells from Jak2 V617F transgenic (JAK2^V617F) mice or control wild-type (WT) mice into lethally irradiated apolipoprotein E-deficient mice. Five weeks after BMT, the JAK2^V617F-BMT mice and WT-BMT mice were subjected to continuous angiotensin II infusion to induce AA formation. Four weeks after angiotensin II infusion, the abdominal aorta diameter in the JAK2^V617F-BMT mice was significantly enlarged compared to that in the WT-BMT mice. Additionally, the abdominal AA-free survival rate was significantly lower in the JAK2^V617F-BMT mice. Hematopoietic JAK2 V617F accelerated aortic elastic lamina degradation as well as activation of matrix metalloproteinase (MMP)-2 and MMP-9 in the abdominal aorta. The numbers of infiltrated macrophages were significantly upregulated in the abdominal aorta of the JAK2^V617F-BMT mice accompanied by STAT3 phosphorylation. The accumulation of BM-derived hematopoietic cells carrying JAK2 V617F in the abdominal aorta was confirmed by use of the reporter green fluorescent proteintransgene. BM-derived macrophages carrying JAK2 V617F showed increases in mRNA expression levels of Mmp2, Mmp9, and Mmp13. Ruxolitinib decreased the abdominal aorta diameter and the incidence of abdominal AA in the JAK2^V617F-BMT mice. Our findings provide a novel feature of vascular complications of AA in MPN with JAK2 V617F.